logging-cookbook.po

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#: howto/logging-cookbook.rst:5
msgid "Logging Cookbook"
msgstr ""

#: howto/logging-cookbook.rst:0
msgid "Author"
msgstr ""

#: howto/logging-cookbook.rst:7
msgid "Vinay Sajip <vinay_sajip at red-dove dot com>"
msgstr ""

#: howto/logging-cookbook.rst:9
msgid ""
"This page contains a number of recipes related to logging, which have been "
"found useful in the past. For links to tutorial and reference information, "
"please see :ref:`cookbook-ref-links`."
msgstr ""

#: howto/logging-cookbook.rst:16
msgid "Using logging in multiple modules"
msgstr ""

#: howto/logging-cookbook.rst:18
msgid ""
"Multiple calls to ``logging.getLogger('someLogger')`` return a reference to "
"the same logger object.  This is true not only within the same module, but "
"also across modules as long as it is in the same Python interpreter "
"process.  It is true for references to the same object; additionally, "
"application code can define and configure a parent logger in one module and "
"create (but not configure) a child logger in a separate module, and all "
"logger calls to the child will pass up to the parent.  Here is a main "
"module::"
msgstr ""

#: howto/logging-cookbook.rst:26
msgid ""
"import logging\n"
"import auxiliary_module\n"
"\n"
"# create logger with 'spam_application'\n"
"logger = logging.getLogger('spam_application')\n"
"logger.setLevel(logging.DEBUG)\n"
"# create file handler which logs even debug messages\n"
"fh = logging.FileHandler('spam.log')\n"
"fh.setLevel(logging.DEBUG)\n"
"# create console handler with a higher log level\n"
"ch = logging.StreamHandler()\n"
"ch.setLevel(logging.ERROR)\n"
"# create formatter and add it to the handlers\n"
"formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - "
"%(message)s')\n"
"fh.setFormatter(formatter)\n"
"ch.setFormatter(formatter)\n"
"# add the handlers to the logger\n"
"logger.addHandler(fh)\n"
"logger.addHandler(ch)\n"
"\n"
"logger.info('creating an instance of auxiliary_module.Auxiliary')\n"
"a = auxiliary_module.Auxiliary()\n"
"logger.info('created an instance of auxiliary_module.Auxiliary')\n"
"logger.info('calling auxiliary_module.Auxiliary.do_something')\n"
"a.do_something()\n"
"logger.info('finished auxiliary_module.Auxiliary.do_something')\n"
"logger.info('calling auxiliary_module.some_function()')\n"
"auxiliary_module.some_function()\n"
"logger.info('done with auxiliary_module.some_function()')"
msgstr ""

#: howto/logging-cookbook.rst:56
msgid "Here is the auxiliary module::"
msgstr ""

#: howto/logging-cookbook.rst:58
msgid ""
"import logging\n"
"\n"
"# create logger\n"
"module_logger = logging.getLogger('spam_application.auxiliary')\n"
"\n"
"class Auxiliary:\n"
"    def __init__(self):\n"
"        self.logger = logging.getLogger('spam_application.auxiliary."
"Auxiliary')\n"
"        self.logger.info('creating an instance of Auxiliary')\n"
"\n"
"    def do_something(self):\n"
"        self.logger.info('doing something')\n"
"        a = 1 + 1\n"
"        self.logger.info('done doing something')\n"
"\n"
"def some_function():\n"
"    module_logger.info('received a call to \"some_function\"')"
msgstr ""

#: howto/logging-cookbook.rst:76
msgid "The output looks like this:"
msgstr ""

#: howto/logging-cookbook.rst:78
msgid ""
"2005-03-23 23:47:11,663 - spam_application - INFO -\n"
"   creating an instance of auxiliary_module.Auxiliary\n"
"2005-03-23 23:47:11,665 - spam_application.auxiliary.Auxiliary - INFO -\n"
"   creating an instance of Auxiliary\n"
"2005-03-23 23:47:11,665 - spam_application - INFO -\n"
"   created an instance of auxiliary_module.Auxiliary\n"
"2005-03-23 23:47:11,668 - spam_application - INFO -\n"
"   calling auxiliary_module.Auxiliary.do_something\n"
"2005-03-23 23:47:11,668 - spam_application.auxiliary.Auxiliary - INFO -\n"
"   doing something\n"
"2005-03-23 23:47:11,669 - spam_application.auxiliary.Auxiliary - INFO -\n"
"   done doing something\n"
"2005-03-23 23:47:11,670 - spam_application - INFO -\n"
"   finished auxiliary_module.Auxiliary.do_something\n"
"2005-03-23 23:47:11,671 - spam_application - INFO -\n"
"   calling auxiliary_module.some_function()\n"
"2005-03-23 23:47:11,672 - spam_application.auxiliary - INFO -\n"
"   received a call to 'some_function'\n"
"2005-03-23 23:47:11,673 - spam_application - INFO -\n"
"   done with auxiliary_module.some_function()"
msgstr ""

#: howto/logging-cookbook.rst:102
msgid "Logging from multiple threads"
msgstr ""

#: howto/logging-cookbook.rst:104
msgid ""
"Logging from multiple threads requires no special effort. The following "
"example shows logging from the main (initial) thread and another thread::"
msgstr ""

#: howto/logging-cookbook.rst:107
msgid ""
"import logging\n"
"import threading\n"
"import time\n"
"\n"
"def worker(arg):\n"
"    while not arg['stop']:\n"
"        logging.debug('Hi from myfunc')\n"
"        time.sleep(0.5)\n"
"\n"
"def main():\n"
"    logging.basicConfig(level=logging.DEBUG, format='%(relativeCreated)6d "
"%(threadName)s %(message)s')\n"
"    info = {'stop': False}\n"
"    thread = threading.Thread(target=worker, args=(info,))\n"
"    thread.start()\n"
"    while True:\n"
"        try:\n"
"            logging.debug('Hello from main')\n"
"            time.sleep(0.75)\n"
"        except KeyboardInterrupt:\n"
"            info['stop'] = True\n"
"            break\n"
"    thread.join()\n"
"\n"
"if __name__ == '__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:133
msgid "When run, the script should print something like the following:"
msgstr ""

#: howto/logging-cookbook.rst:135
msgid ""
"   0 Thread-1 Hi from myfunc\n"
"   3 MainThread Hello from main\n"
" 505 Thread-1 Hi from myfunc\n"
" 755 MainThread Hello from main\n"
"1007 Thread-1 Hi from myfunc\n"
"1507 MainThread Hello from main\n"
"1508 Thread-1 Hi from myfunc\n"
"2010 Thread-1 Hi from myfunc\n"
"2258 MainThread Hello from main\n"
"2512 Thread-1 Hi from myfunc\n"
"3009 MainThread Hello from main\n"
"3013 Thread-1 Hi from myfunc\n"
"3515 Thread-1 Hi from myfunc\n"
"3761 MainThread Hello from main\n"
"4017 Thread-1 Hi from myfunc\n"
"4513 MainThread Hello from main\n"
"4518 Thread-1 Hi from myfunc"
msgstr ""

#: howto/logging-cookbook.rst:155
msgid ""
"This shows the logging output interspersed as one might expect. This "
"approach works for more threads than shown here, of course."
msgstr ""

#: howto/logging-cookbook.rst:159
msgid "Multiple handlers and formatters"
msgstr ""

#: howto/logging-cookbook.rst:161
msgid ""
"Loggers are plain Python objects.  The :meth:`~Logger.addHandler` method has "
"no minimum or maximum quota for the number of handlers you may add.  "
"Sometimes it will be beneficial for an application to log all messages of "
"all severities to a text file while simultaneously logging errors or above "
"to the console.  To set this up, simply configure the appropriate handlers.  "
"The logging calls in the application code will remain unchanged.  Here is a "
"slight modification to the previous simple module-based configuration "
"example::"
msgstr ""

#: howto/logging-cookbook.rst:169
msgid ""
"import logging\n"
"\n"
"logger = logging.getLogger('simple_example')\n"
"logger.setLevel(logging.DEBUG)\n"
"# create file handler which logs even debug messages\n"
"fh = logging.FileHandler('spam.log')\n"
"fh.setLevel(logging.DEBUG)\n"
"# create console handler with a higher log level\n"
"ch = logging.StreamHandler()\n"
"ch.setLevel(logging.ERROR)\n"
"# create formatter and add it to the handlers\n"
"formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - "
"%(message)s')\n"
"ch.setFormatter(formatter)\n"
"fh.setFormatter(formatter)\n"
"# add the handlers to logger\n"
"logger.addHandler(ch)\n"
"logger.addHandler(fh)\n"
"\n"
"# 'application' code\n"
"logger.debug('debug message')\n"
"logger.info('info message')\n"
"logger.warning('warn message')\n"
"logger.error('error message')\n"
"logger.critical('critical message')"
msgstr ""

#: howto/logging-cookbook.rst:194
msgid ""
"Notice that the 'application' code does not care about multiple handlers.  "
"All that changed was the addition and configuration of a new handler named "
"*fh*."
msgstr ""

#: howto/logging-cookbook.rst:197
msgid ""
"The ability to create new handlers with higher- or lower-severity filters "
"can be very helpful when writing and testing an application.  Instead of "
"using many ``print`` statements for debugging, use ``logger.debug``: Unlike "
"the print statements, which you will have to delete or comment out later, "
"the logger.debug statements can remain intact in the source code and remain "
"dormant until you need them again.  At that time, the only change that needs "
"to happen is to modify the severity level of the logger and/or handler to "
"debug."
msgstr ""

#: howto/logging-cookbook.rst:208
msgid "Logging to multiple destinations"
msgstr ""

#: howto/logging-cookbook.rst:210
msgid ""
"Let's say you want to log to console and file with different message formats "
"and in differing circumstances. Say you want to log messages with levels of "
"DEBUG and higher to file, and those messages at level INFO and higher to the "
"console. Let's also assume that the file should contain timestamps, but the "
"console messages should not. Here's how you can achieve this::"
msgstr ""

#: howto/logging-cookbook.rst:216
msgid ""
"import logging\n"
"\n"
"# set up logging to file - see previous section for more details\n"
"logging.basicConfig(level=logging.DEBUG,\n"
"                    format='%(asctime)s %(name)-12s %(levelname)-8s "
"%(message)s',\n"
"                    datefmt='%m-%d %H:%M',\n"
"                    filename='/tmp/myapp.log',\n"
"                    filemode='w')\n"
"# define a Handler which writes INFO messages or higher to the sys.stderr\n"
"console = logging.StreamHandler()\n"
"console.setLevel(logging.INFO)\n"
"# set a format which is simpler for console use\n"
"formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')\n"
"# tell the handler to use this format\n"
"console.setFormatter(formatter)\n"
"# add the handler to the root logger\n"
"logging.getLogger('').addHandler(console)\n"
"\n"
"# Now, we can log to the root logger, or any other logger. First the "
"root...\n"
"logging.info('Jackdaws love my big sphinx of quartz.')\n"
"\n"
"# Now, define a couple of other loggers which might represent areas in your\n"
"# application:\n"
"\n"
"logger1 = logging.getLogger('myapp.area1')\n"
"logger2 = logging.getLogger('myapp.area2')\n"
"\n"
"logger1.debug('Quick zephyrs blow, vexing daft Jim.')\n"
"logger1.info('How quickly daft jumping zebras vex.')\n"
"logger2.warning('Jail zesty vixen who grabbed pay from quack.')\n"
"logger2.error('The five boxing wizards jump quickly.')"
msgstr ""

#: howto/logging-cookbook.rst:248
msgid "When you run this, on the console you will see"
msgstr ""

#: howto/logging-cookbook.rst:250
msgid ""
"root        : INFO     Jackdaws love my big sphinx of quartz.\n"
"myapp.area1 : INFO     How quickly daft jumping zebras vex.\n"
"myapp.area2 : WARNING  Jail zesty vixen who grabbed pay from quack.\n"
"myapp.area2 : ERROR    The five boxing wizards jump quickly."
msgstr ""

#: howto/logging-cookbook.rst:257
msgid "and in the file you will see something like"
msgstr ""

#: howto/logging-cookbook.rst:259
msgid ""
"10-22 22:19 root         INFO     Jackdaws love my big sphinx of quartz.\n"
"10-22 22:19 myapp.area1  DEBUG    Quick zephyrs blow, vexing daft Jim.\n"
"10-22 22:19 myapp.area1  INFO     How quickly daft jumping zebras vex.\n"
"10-22 22:19 myapp.area2  WARNING  Jail zesty vixen who grabbed pay from "
"quack.\n"
"10-22 22:19 myapp.area2  ERROR    The five boxing wizards jump quickly."
msgstr ""

#: howto/logging-cookbook.rst:267
msgid ""
"As you can see, the DEBUG message only shows up in the file. The other "
"messages are sent to both destinations."
msgstr ""

#: howto/logging-cookbook.rst:270
msgid ""
"This example uses console and file handlers, but you can use any number and "
"combination of handlers you choose."
msgstr ""

#: howto/logging-cookbook.rst:273
msgid ""
"Note that the above choice of log filename ``/tmp/myapp.log`` implies use of "
"a standard location for temporary files on POSIX systems. On Windows, you "
"may need to choose a different directory name for the log - just ensure that "
"the directory exists and that you have the permissions to create and update "
"files in it."
msgstr ""

#: howto/logging-cookbook.rst:282
msgid "Custom handling of levels"
msgstr ""

#: howto/logging-cookbook.rst:284
msgid ""
"Sometimes, you might want to do something slightly different from the "
"standard handling of levels in handlers, where all levels above a threshold "
"get processed by a handler. To do this, you need to use filters. Let's look "
"at a scenario where you want to arrange things as follows:"
msgstr ""

#: howto/logging-cookbook.rst:289
msgid "Send messages of severity ``INFO`` and ``WARNING`` to ``sys.stdout``"
msgstr ""

#: howto/logging-cookbook.rst:290
msgid "Send messages of severity ``ERROR`` and above to ``sys.stderr``"
msgstr ""

#: howto/logging-cookbook.rst:291
msgid "Send messages of severity ``DEBUG`` and above to file ``app.log``"
msgstr ""

#: howto/logging-cookbook.rst:293
msgid "Suppose you configure logging with the following JSON:"
msgstr ""

#: howto/logging-cookbook.rst:295
msgid ""
"{\n"
"    \"version\": 1,\n"
"    \"disable_existing_loggers\": false,\n"
"    \"formatters\": {\n"
"        \"simple\": {\n"
"            \"format\": \"%(levelname)-8s - %(message)s\"\n"
"        }\n"
"    },\n"
"    \"handlers\": {\n"
"        \"stdout\": {\n"
"            \"class\": \"logging.StreamHandler\",\n"
"            \"level\": \"INFO\",\n"
"            \"formatter\": \"simple\",\n"
"            \"stream\": \"ext://sys.stdout\"\n"
"        },\n"
"        \"stderr\": {\n"
"            \"class\": \"logging.StreamHandler\",\n"
"            \"level\": \"ERROR\",\n"
"            \"formatter\": \"simple\",\n"
"            \"stream\": \"ext://sys.stderr\"\n"
"        },\n"
"        \"file\": {\n"
"            \"class\": \"logging.FileHandler\",\n"
"            \"formatter\": \"simple\",\n"
"            \"filename\": \"app.log\",\n"
"            \"mode\": \"w\"\n"
"        }\n"
"    },\n"
"    \"root\": {\n"
"        \"level\": \"DEBUG\",\n"
"        \"handlers\": [\n"
"            \"stderr\",\n"
"            \"stdout\",\n"
"            \"file\"\n"
"        ]\n"
"    }\n"
"}"
msgstr ""

#: howto/logging-cookbook.rst:335
msgid ""
"This configuration does *almost* what we want, except that ``sys.stdout`` "
"would show messages of severity ``ERROR`` and above as well as ``INFO`` and "
"``WARNING`` messages. To prevent this, we can set up a filter which excludes "
"those messages and add it to the relevant handler. This can be configured by "
"adding a ``filters`` section parallel to ``formatters`` and ``handlers``:"
msgstr ""

#: howto/logging-cookbook.rst:341
msgid ""
"{\n"
"    \"filters\": {\n"
"        \"warnings_and_below\": {\n"
"            \"()\" : \"__main__.filter_maker\",\n"
"            \"level\": \"WARNING\"\n"
"        }\n"
"    }\n"
"}"
msgstr ""

#: howto/logging-cookbook.rst:352
msgid "and changing the section on the ``stdout`` handler to add it:"
msgstr ""

#: howto/logging-cookbook.rst:354
msgid ""
"{\n"
"    \"stdout\": {\n"
"        \"class\": \"logging.StreamHandler\",\n"
"        \"level\": \"INFO\",\n"
"        \"formatter\": \"simple\",\n"
"        \"stream\": \"ext://sys.stdout\",\n"
"        \"filters\": [\"warnings_and_below\"]\n"
"    }\n"
"}"
msgstr ""

#: howto/logging-cookbook.rst:366
msgid ""
"A filter is just a function, so we can define the ``filter_maker`` (a "
"factory function) as follows:"
msgstr ""

#: howto/logging-cookbook.rst:369
msgid ""
"def filter_maker(level):\n"
"    level = getattr(logging, level)\n"
"\n"
"    def filter(record):\n"
"        return record.levelno <= level\n"
"\n"
"    return filter"
msgstr ""

#: howto/logging-cookbook.rst:379
msgid ""
"This converts the string argument passed in to a numeric level, and returns "
"a function which only returns ``True`` if the level of the passed in record "
"is at or below the specified level. Note that in this example I have defined "
"the ``filter_maker`` in a test script ``main.py`` that I run from the "
"command line, so its module will be ``__main__`` - hence the ``__main__."
"filter_maker`` in the filter configuration. You will need to change that if "
"you define it in a different module."
msgstr ""

#: howto/logging-cookbook.rst:387
msgid "With the filter added, we can run ``main.py``, which in full is:"
msgstr ""

#: howto/logging-cookbook.rst:389
msgid ""
"import json\n"
"import logging\n"
"import logging.config\n"
"\n"
"CONFIG = '''\n"
"{\n"
"    \"version\": 1,\n"
"    \"disable_existing_loggers\": false,\n"
"    \"formatters\": {\n"
"        \"simple\": {\n"
"            \"format\": \"%(levelname)-8s - %(message)s\"\n"
"        }\n"
"    },\n"
"    \"filters\": {\n"
"        \"warnings_and_below\": {\n"
"            \"()\" : \"__main__.filter_maker\",\n"
"            \"level\": \"WARNING\"\n"
"        }\n"
"    },\n"
"    \"handlers\": {\n"
"        \"stdout\": {\n"
"            \"class\": \"logging.StreamHandler\",\n"
"            \"level\": \"INFO\",\n"
"            \"formatter\": \"simple\",\n"
"            \"stream\": \"ext://sys.stdout\",\n"
"            \"filters\": [\"warnings_and_below\"]\n"
"        },\n"
"        \"stderr\": {\n"
"            \"class\": \"logging.StreamHandler\",\n"
"            \"level\": \"ERROR\",\n"
"            \"formatter\": \"simple\",\n"
"            \"stream\": \"ext://sys.stderr\"\n"
"        },\n"
"        \"file\": {\n"
"            \"class\": \"logging.FileHandler\",\n"
"            \"formatter\": \"simple\",\n"
"            \"filename\": \"app.log\",\n"
"            \"mode\": \"w\"\n"
"        }\n"
"    },\n"
"    \"root\": {\n"
"        \"level\": \"DEBUG\",\n"
"        \"handlers\": [\n"
"            \"stderr\",\n"
"            \"stdout\",\n"
"            \"file\"\n"
"        ]\n"
"    }\n"
"}\n"
"'''\n"
"\n"
"def filter_maker(level):\n"
"    level = getattr(logging, level)\n"
"\n"
"    def filter(record):\n"
"        return record.levelno <= level\n"
"\n"
"    return filter\n"
"\n"
"logging.config.dictConfig(json.loads(CONFIG))\n"
"logging.debug('A DEBUG message')\n"
"logging.info('An INFO message')\n"
"logging.warning('A WARNING message')\n"
"logging.error('An ERROR message')\n"
"logging.critical('A CRITICAL message')"
msgstr ""

#: howto/logging-cookbook.rst:457
msgid "And after running it like this:"
msgstr ""

#: howto/logging-cookbook.rst:459
msgid "python main.py 2>stderr.log >stdout.log"
msgstr ""

#: howto/logging-cookbook.rst:463
msgid "We can see the results are as expected:"
msgstr ""

#: howto/logging-cookbook.rst:465
msgid ""
"$ more *.log\n"
"::::::::::::::\n"
"app.log\n"
"::::::::::::::\n"
"DEBUG    - A DEBUG message\n"
"INFO     - An INFO message\n"
"WARNING  - A WARNING message\n"
"ERROR    - An ERROR message\n"
"CRITICAL - A CRITICAL message\n"
"::::::::::::::\n"
"stderr.log\n"
"::::::::::::::\n"
"ERROR    - An ERROR message\n"
"CRITICAL - A CRITICAL message\n"
"::::::::::::::\n"
"stdout.log\n"
"::::::::::::::\n"
"INFO     - An INFO message\n"
"WARNING  - A WARNING message"
msgstr ""

#: howto/logging-cookbook.rst:489
msgid "Configuration server example"
msgstr ""

#: howto/logging-cookbook.rst:491
msgid "Here is an example of a module using the logging configuration server::"
msgstr ""

#: howto/logging-cookbook.rst:493
msgid ""
"import logging\n"
"import logging.config\n"
"import time\n"
"import os\n"
"\n"
"# read initial config file\n"
"logging.config.fileConfig('logging.conf')\n"
"\n"
"# create and start listener on port 9999\n"
"t = logging.config.listen(9999)\n"
"t.start()\n"
"\n"
"logger = logging.getLogger('simpleExample')\n"
"\n"
"try:\n"
"    # loop through logging calls to see the difference\n"
"    # new configurations make, until Ctrl+C is pressed\n"
"    while True:\n"
"        logger.debug('debug message')\n"
"        logger.info('info message')\n"
"        logger.warning('warn message')\n"
"        logger.error('error message')\n"
"        logger.critical('critical message')\n"
"        time.sleep(5)\n"
"except KeyboardInterrupt:\n"
"    # cleanup\n"
"    logging.config.stopListening()\n"
"    t.join()"
msgstr ""

#: howto/logging-cookbook.rst:522
msgid ""
"And here is a script that takes a filename and sends that file to the "
"server, properly preceded with the binary-encoded length, as the new logging "
"configuration::"
msgstr ""

#: howto/logging-cookbook.rst:526
msgid ""
"#!/usr/bin/env python\n"
"import socket, sys, struct\n"
"\n"
"with open(sys.argv[1], 'rb') as f:\n"
"    data_to_send = f.read()\n"
"\n"
"HOST = 'localhost'\n"
"PORT = 9999\n"
"s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)\n"
"print('connecting...')\n"
"s.connect((HOST, PORT))\n"
"print('sending config...')\n"
"s.send(struct.pack('>L', len(data_to_send)))\n"
"s.send(data_to_send)\n"
"s.close()\n"
"print('complete')"
msgstr ""

#: howto/logging-cookbook.rst:547
msgid "Dealing with handlers that block"
msgstr ""

#: howto/logging-cookbook.rst:551
msgid ""
"Sometimes you have to get your logging handlers to do their work without "
"blocking the thread you're logging from. This is common in web applications, "
"though of course it also occurs in other scenarios."
msgstr ""

#: howto/logging-cookbook.rst:555
msgid ""
"A common culprit which demonstrates sluggish behaviour is the :class:"
"`SMTPHandler`: sending emails can take a long time, for a number of reasons "
"outside the developer's control (for example, a poorly performing mail or "
"network infrastructure). But almost any network-based handler can block: "
"Even a :class:`SocketHandler` operation may do a DNS query under the hood "
"which is too slow (and this query can be deep in the socket library code, "
"below the Python layer, and outside your control)."
msgstr ""

#: howto/logging-cookbook.rst:563
msgid ""
"One solution is to use a two-part approach. For the first part, attach only "
"a :class:`QueueHandler` to those loggers which are accessed from performance-"
"critical threads. They simply write to their queue, which can be sized to a "
"large enough capacity or initialized with no upper bound to their size. The "
"write to the queue will typically be accepted quickly, though you will "
"probably need to catch the :exc:`queue.Full` exception as a precaution in "
"your code. If you are a library developer who has performance-critical "
"threads in their code, be sure to document this (together with a suggestion "
"to attach only ``QueueHandlers`` to your loggers) for the benefit of other "
"developers who will use your code."
msgstr ""

#: howto/logging-cookbook.rst:574
msgid ""
"The second part of the solution is :class:`QueueListener`, which has been "
"designed as the counterpart to :class:`QueueHandler`.  A :class:"
"`QueueListener` is very simple: it's passed a queue and some handlers, and "
"it fires up an internal thread which listens to its queue for LogRecords "
"sent from ``QueueHandlers`` (or any other source of ``LogRecords``, for that "
"matter). The ``LogRecords`` are removed from the queue and passed to the "
"handlers for processing."
msgstr ""

#: howto/logging-cookbook.rst:582
msgid ""
"The advantage of having a separate :class:`QueueListener` class is that you "
"can use the same instance to service multiple ``QueueHandlers``. This is "
"more resource-friendly than, say, having threaded versions of the existing "
"handler classes, which would eat up one thread per handler for no particular "
"benefit."
msgstr ""

#: howto/logging-cookbook.rst:587
msgid "An example of using these two classes follows (imports omitted)::"
msgstr ""

#: howto/logging-cookbook.rst:589
msgid ""
"que = queue.Queue(-1)  # no limit on size\n"
"queue_handler = QueueHandler(que)\n"
"handler = logging.StreamHandler()\n"
"listener = QueueListener(que, handler)\n"
"root = logging.getLogger()\n"
"root.addHandler(queue_handler)\n"
"formatter = logging.Formatter('%(threadName)s: %(message)s')\n"
"handler.setFormatter(formatter)\n"
"listener.start()\n"
"# The log output will display the thread which generated\n"
"# the event (the main thread) rather than the internal\n"
"# thread which monitors the internal queue. This is what\n"
"# you want to happen.\n"
"root.warning('Look out!')\n"
"listener.stop()"
msgstr ""

#: howto/logging-cookbook.rst:605
msgid "which, when run, will produce:"
msgstr ""

#: howto/logging-cookbook.rst:607
msgid "MainThread: Look out!"
msgstr ""

#: howto/logging-cookbook.rst:611
msgid ""
"Although the earlier discussion wasn't specifically talking about async "
"code, but rather about slow logging handlers, it should be noted that when "
"logging from async code, network and even file handlers could lead to "
"problems (blocking the event loop) because some logging is done from :mod:"
"`asyncio` internals. It might be best, if any async code is used in an "
"application, to use the above approach for logging, so that any blocking "
"code runs only in the ``QueueListener`` thread."
msgstr ""

#: howto/logging-cookbook.rst:619
msgid ""
"Prior to Python 3.5, the :class:`QueueListener` always passed every message "
"received from the queue to every handler it was initialized with. (This was "
"because it was assumed that level filtering was all done on the other side, "
"where the queue is filled.) From 3.5 onwards, this behaviour can be changed "
"by passing a keyword argument ``respect_handler_level=True`` to the "
"listener's constructor. When this is done, the listener compares the level "
"of each message with the handler's level, and only passes a message to a "
"handler if it's appropriate to do so."
msgstr ""

#: howto/logging-cookbook.rst:632
msgid "Sending and receiving logging events across a network"
msgstr ""

#: howto/logging-cookbook.rst:634
msgid ""
"Let's say you want to send logging events across a network, and handle them "
"at the receiving end. A simple way of doing this is attaching a :class:"
"`SocketHandler` instance to the root logger at the sending end::"
msgstr ""

#: howto/logging-cookbook.rst:638
msgid ""
"import logging, logging.handlers\n"
"\n"
"rootLogger = logging.getLogger('')\n"
"rootLogger.setLevel(logging.DEBUG)\n"
"socketHandler = logging.handlers.SocketHandler('localhost',\n"
"                    logging.handlers.DEFAULT_TCP_LOGGING_PORT)\n"
"# don't bother with a formatter, since a socket handler sends the event as\n"
"# an unformatted pickle\n"
"rootLogger.addHandler(socketHandler)\n"
"\n"
"# Now, we can log to the root logger, or any other logger. First the "
"root...\n"
"logging.info('Jackdaws love my big sphinx of quartz.')\n"
"\n"
"# Now, define a couple of other loggers which might represent areas in your\n"
"# application:\n"
"\n"
"logger1 = logging.getLogger('myapp.area1')\n"
"logger2 = logging.getLogger('myapp.area2')\n"
"\n"
"logger1.debug('Quick zephyrs blow, vexing daft Jim.')\n"
"logger1.info('How quickly daft jumping zebras vex.')\n"
"logger2.warning('Jail zesty vixen who grabbed pay from quack.')\n"
"logger2.error('The five boxing wizards jump quickly.')"
msgstr ""

#: howto/logging-cookbook.rst:662
msgid ""
"At the receiving end, you can set up a receiver using the :mod:"
"`socketserver` module. Here is a basic working example::"
msgstr ""

#: howto/logging-cookbook.rst:665
msgid ""
"import pickle\n"
"import logging\n"
"import logging.handlers\n"
"import socketserver\n"
"import struct\n"
"\n"
"\n"
"class LogRecordStreamHandler(socketserver.StreamRequestHandler):\n"
"    \"\"\"Handler for a streaming logging request.\n"
"\n"
"    This basically logs the record using whatever logging policy is\n"
"    configured locally.\n"
"    \"\"\"\n"
"\n"
"    def handle(self):\n"
"        \"\"\"\n"
"        Handle multiple requests - each expected to be a 4-byte length,\n"
"        followed by the LogRecord in pickle format. Logs the record\n"
"        according to whatever policy is configured locally.\n"
"        \"\"\"\n"
"        while True:\n"
"            chunk = self.connection.recv(4)\n"
"            if len(chunk) < 4:\n"
"                break\n"
"            slen = struct.unpack('>L', chunk)[0]\n"
"            chunk = self.connection.recv(slen)\n"
"            while len(chunk) < slen:\n"
"                chunk = chunk + self.connection.recv(slen - len(chunk))\n"
"            obj = self.unPickle(chunk)\n"
"            record = logging.makeLogRecord(obj)\n"
"            self.handleLogRecord(record)\n"
"\n"
"    def unPickle(self, data):\n"
"        return pickle.loads(data)\n"
"\n"
"    def handleLogRecord(self, record):\n"
"        # if a name is specified, we use the named logger rather than the "
"one\n"
"        # implied by the record.\n"
"        if self.server.logname is not None:\n"
"            name = self.server.logname\n"
"        else:\n"
"            name = record.name\n"
"        logger = logging.getLogger(name)\n"
"        # N.B. EVERY record gets logged. This is because Logger.handle\n"
"        # is normally called AFTER logger-level filtering. If you want\n"
"        # to do filtering, do it at the client end to save wasting\n"
"        # cycles and network bandwidth!\n"
"        logger.handle(record)\n"
"\n"
"class LogRecordSocketReceiver(socketserver.ThreadingTCPServer):\n"
"    \"\"\"\n"
"    Simple TCP socket-based logging receiver suitable for testing.\n"
"    \"\"\"\n"
"\n"
"    allow_reuse_address = True\n"
"\n"
"    def __init__(self, host='localhost',\n"
"                 port=logging.handlers.DEFAULT_TCP_LOGGING_PORT,\n"
"                 handler=LogRecordStreamHandler):\n"
"        socketserver.ThreadingTCPServer.__init__(self, (host, port), "
"handler)\n"
"        self.abort = 0\n"
"        self.timeout = 1\n"
"        self.logname = None\n"
"\n"
"    def serve_until_stopped(self):\n"
"        import select\n"
"        abort = 0\n"
"        while not abort:\n"
"            rd, wr, ex = select.select([self.socket.fileno()],\n"
"                                       [], [],\n"
"                                       self.timeout)\n"
"            if rd:\n"
"                self.handle_request()\n"
"            abort = self.abort\n"
"\n"
"def main():\n"
"    logging.basicConfig(\n"
"        format='%(relativeCreated)5d %(name)-15s %(levelname)-8s "
"%(message)s')\n"
"    tcpserver = LogRecordSocketReceiver()\n"
"    print('About to start TCP server...')\n"
"    tcpserver.serve_until_stopped()\n"
"\n"
"if __name__ == '__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:750
msgid ""
"First run the server, and then the client. On the client side, nothing is "
"printed on the console; on the server side, you should see something like:"
msgstr ""

#: howto/logging-cookbook.rst:753
msgid ""
"About to start TCP server...\n"
"   59 root            INFO     Jackdaws love my big sphinx of quartz.\n"
"   59 myapp.area1     DEBUG    Quick zephyrs blow, vexing daft Jim.\n"
"   69 myapp.area1     INFO     How quickly daft jumping zebras vex.\n"
"   69 myapp.area2     WARNING  Jail zesty vixen who grabbed pay from quack.\n"
"   69 myapp.area2     ERROR    The five boxing wizards jump quickly."
msgstr ""

#: howto/logging-cookbook.rst:762
msgid ""
"Note that there are some security issues with pickle in some scenarios. If "
"these affect you, you can use an alternative serialization scheme by "
"overriding the :meth:`~SocketHandler.makePickle` method and implementing "
"your alternative there, as well as adapting the above script to use your "
"alternative serialization."
msgstr ""

#: howto/logging-cookbook.rst:770
msgid "Running a logging socket listener in production"
msgstr ""

#: howto/logging-cookbook.rst:774
msgid ""
"To run a logging listener in production, you may need to use a process-"
"management tool such as `Supervisor <http://supervisord.org/>`_. `Here is a "
"Gist <socket-listener-gist_>`__ which provides the bare-bones files to run "
"the above functionality using Supervisor. It consists of the following files:"
msgstr ""

#: howto/logging-cookbook.rst:781
msgid "File"
msgstr ""

#: howto/logging-cookbook.rst:781
msgid "Purpose"
msgstr ""

#: howto/logging-cookbook.rst:783
msgid ":file:`prepare.sh`"
msgstr ""

#: howto/logging-cookbook.rst:783
msgid "A Bash script to prepare the environment for testing"
msgstr ""

#: howto/logging-cookbook.rst:786
msgid ":file:`supervisor.conf`"
msgstr ""

#: howto/logging-cookbook.rst:786
msgid ""
"The Supervisor configuration file, which has entries for the listener and a "
"multi-process web application"
msgstr ""

#: howto/logging-cookbook.rst:790
msgid ":file:`ensure_app.sh`"
msgstr ""

#: howto/logging-cookbook.rst:790
msgid ""
"A Bash script to ensure that Supervisor is running with the above "
"configuration"
msgstr ""

#: howto/logging-cookbook.rst:793
msgid ":file:`log_listener.py`"
msgstr ""

#: howto/logging-cookbook.rst:793
msgid ""
"The socket listener program which receives log events and records them to a "
"file"
msgstr ""

#: howto/logging-cookbook.rst:796
msgid ":file:`main.py`"
msgstr ""

#: howto/logging-cookbook.rst:796
msgid ""
"A simple web application which performs logging via a socket connected to "
"the listener"
msgstr ""

#: howto/logging-cookbook.rst:799
msgid ":file:`webapp.json`"
msgstr ""

#: howto/logging-cookbook.rst:799
msgid "A JSON configuration file for the web application"
msgstr ""

#: howto/logging-cookbook.rst:801
msgid ":file:`client.py`"
msgstr ""

#: howto/logging-cookbook.rst:801
msgid "A Python script to exercise the web application"
msgstr ""

#: howto/logging-cookbook.rst:804
msgid ""
"The web application uses `Gunicorn <https://gunicorn.org/>`_, which is a "
"popular web application server that starts multiple worker processes to "
"handle requests. This example setup shows how the workers can write to the "
"same log file without conflicting with one another --- they all go through "
"the socket listener."
msgstr ""

#: howto/logging-cookbook.rst:809
msgid "To test these files, do the following in a POSIX environment:"
msgstr ""

#: howto/logging-cookbook.rst:811
msgid ""
"Download `the Gist <socket-listener-gist_>`__ as a ZIP archive using the :"
"guilabel:`Download ZIP` button."
msgstr ""

#: howto/logging-cookbook.rst:814
msgid "Unzip the above files from the archive into a scratch directory."
msgstr ""

#: howto/logging-cookbook.rst:816
msgid ""
"In the scratch directory, run ``bash prepare.sh`` to get things ready. This "
"creates a :file:`run` subdirectory to contain Supervisor-related and log "
"files, and a :file:`venv` subdirectory to contain a virtual environment into "
"which ``bottle``, ``gunicorn`` and ``supervisor`` are installed."
msgstr ""

#: howto/logging-cookbook.rst:821
msgid ""
"Run ``bash ensure_app.sh`` to ensure that Supervisor is running with the "
"above configuration."
msgstr ""

#: howto/logging-cookbook.rst:824
msgid ""
"Run ``venv/bin/python client.py`` to exercise the web application, which "
"will lead to records being written to the log."
msgstr ""

#: howto/logging-cookbook.rst:827
msgid ""
"Inspect the log files in the :file:`run` subdirectory. You should see the "
"most recent log lines in files matching the pattern :file:`app.log*`. They "
"won't be in any particular order, since they have been handled concurrently "
"by different worker processes in a non-deterministic way."
msgstr ""

#: howto/logging-cookbook.rst:832
msgid ""
"You can shut down the listener and the web application by running ``venv/bin/"
"supervisorctl -c supervisor.conf shutdown``."
msgstr ""

#: howto/logging-cookbook.rst:835
msgid ""
"You may need to tweak the configuration files in the unlikely event that the "
"configured ports clash with something else in your test environment."
msgstr ""

#: howto/logging-cookbook.rst:843
msgid "Adding contextual information to your logging output"
msgstr ""

#: howto/logging-cookbook.rst:845
msgid ""
"Sometimes you want logging output to contain contextual information in "
"addition to the parameters passed to the logging call. For example, in a "
"networked application, it may be desirable to log client-specific "
"information in the log (e.g. remote client's username, or IP address). "
"Although you could use the *extra* parameter to achieve this, it's not "
"always convenient to pass the information in this way. While it might be "
"tempting to create :class:`Logger` instances on a per-connection basis, this "
"is not a good idea because these instances are not garbage collected. While "
"this is not a problem in practice, when the number of :class:`Logger` "
"instances is dependent on the level of granularity you want to use in "
"logging an application, it could be hard to manage if the number of :class:"
"`Logger` instances becomes effectively unbounded."
msgstr ""

#: howto/logging-cookbook.rst:860
msgid "Using LoggerAdapters to impart contextual information"
msgstr ""

#: howto/logging-cookbook.rst:862
msgid ""
"An easy way in which you can pass contextual information to be output along "
"with logging event information is to use the :class:`LoggerAdapter` class. "
"This class is designed to look like a :class:`Logger`, so that you can call :"
"meth:`debug`, :meth:`info`, :meth:`warning`, :meth:`error`, :meth:"
"`exception`, :meth:`critical` and :meth:`log`. These methods have the same "
"signatures as their counterparts in :class:`Logger`, so you can use the two "
"types of instances interchangeably."
msgstr ""

#: howto/logging-cookbook.rst:870
msgid ""
"When you create an instance of :class:`LoggerAdapter`, you pass it a :class:"
"`Logger` instance and a dict-like object which contains your contextual "
"information. When you call one of the logging methods on an instance of :"
"class:`LoggerAdapter`, it delegates the call to the underlying instance of :"
"class:`Logger` passed to its constructor, and arranges to pass the "
"contextual information in the delegated call. Here's a snippet from the code "
"of :class:`LoggerAdapter`::"
msgstr ""

#: howto/logging-cookbook.rst:878
msgid ""
"def debug(self, msg, /, *args, **kwargs):\n"
"    \"\"\"\n"
"    Delegate a debug call to the underlying logger, after adding\n"
"    contextual information from this adapter instance.\n"
"    \"\"\"\n"
"    msg, kwargs = self.process(msg, kwargs)\n"
"    self.logger.debug(msg, *args, **kwargs)"
msgstr ""

#: howto/logging-cookbook.rst:886
msgid ""
"The :meth:`~LoggerAdapter.process` method of :class:`LoggerAdapter` is where "
"the contextual information is added to the logging output. It's passed the "
"message and keyword arguments of the logging call, and it passes back "
"(potentially) modified versions of these to use in the call to the "
"underlying logger. The default implementation of this method leaves the "
"message alone, but inserts an 'extra' key in the keyword argument whose "
"value is the dict-like object passed to the constructor. Of course, if you "
"had passed an 'extra' keyword argument in the call to the adapter, it will "
"be silently overwritten."
msgstr ""

#: howto/logging-cookbook.rst:895
msgid ""
"The advantage of using 'extra' is that the values in the dict-like object "
"are merged into the :class:`LogRecord` instance's __dict__, allowing you to "
"use customized strings with your :class:`Formatter` instances which know "
"about the keys of the dict-like object. If you need a different method, e.g. "
"if you want to prepend or append the contextual information to the message "
"string, you just need to subclass :class:`LoggerAdapter` and override :meth:"
"`~LoggerAdapter.process` to do what you need. Here is a simple example::"
msgstr ""

#: howto/logging-cookbook.rst:903
msgid ""
"class CustomAdapter(logging.LoggerAdapter):\n"
"    \"\"\"\n"
"    This example adapter expects the passed in dict-like object to have a\n"
"    'connid' key, whose value in brackets is prepended to the log message.\n"
"    \"\"\"\n"
"    def process(self, msg, kwargs):\n"
"        return '[%s] %s' % (self.extra['connid'], msg), kwargs"
msgstr ""

#: howto/logging-cookbook.rst:911
msgid "which you can use like this::"
msgstr ""

#: howto/logging-cookbook.rst:913
msgid ""
"logger = logging.getLogger(__name__)\n"
"adapter = CustomAdapter(logger, {'connid': some_conn_id})"
msgstr ""

#: howto/logging-cookbook.rst:916
msgid ""
"Then any events that you log to the adapter will have the value of "
"``some_conn_id`` prepended to the log messages."
msgstr ""

#: howto/logging-cookbook.rst:920
msgid "Using objects other than dicts to pass contextual information"
msgstr ""

#: howto/logging-cookbook.rst:922
msgid ""
"You don't need to pass an actual dict to a :class:`LoggerAdapter` - you "
"could pass an instance of a class which implements ``__getitem__`` and "
"``__iter__`` so that it looks like a dict to logging. This would be useful "
"if you want to generate values dynamically (whereas the values in a dict "
"would be constant)."
msgstr ""

#: howto/logging-cookbook.rst:931
msgid "Using Filters to impart contextual information"
msgstr ""

#: howto/logging-cookbook.rst:933
msgid ""
"You can also add contextual information to log output using a user-defined :"
"class:`Filter`. ``Filter`` instances are allowed to modify the "
"``LogRecords`` passed to them, including adding additional attributes which "
"can then be output using a suitable format string, or if needed a custom :"
"class:`Formatter`."
msgstr ""

#: howto/logging-cookbook.rst:938
msgid ""
"For example in a web application, the request being processed (or at least, "
"the interesting parts of it) can be stored in a threadlocal (:class:"
"`threading.local`) variable, and then accessed from a ``Filter`` to add, "
"say, information from the request - say, the remote IP address and remote "
"user's username - to the ``LogRecord``, using the attribute names 'ip' and "
"'user' as in the ``LoggerAdapter`` example above. In that case, the same "
"format string can be used to get similar output to that shown above. Here's "
"an example script::"
msgstr ""

#: howto/logging-cookbook.rst:947
msgid ""
"import logging\n"
"from random import choice\n"
"\n"
"class ContextFilter(logging.Filter):\n"
"    \"\"\"\n"
"    This is a filter which injects contextual information into the log.\n"
"\n"
"    Rather than use actual contextual information, we just use random\n"
"    data in this demo.\n"
"    \"\"\"\n"
"\n"
"    USERS = ['jim', 'fred', 'sheila']\n"
"    IPS = ['123.231.231.123', '127.0.0.1', '192.168.0.1']\n"
"\n"
"    def filter(self, record):\n"
"\n"
"        record.ip = choice(ContextFilter.IPS)\n"
"        record.user = choice(ContextFilter.USERS)\n"
"        return True\n"
"\n"
"if __name__ == '__main__':\n"
"    levels = (logging.DEBUG, logging.INFO, logging.WARNING, logging.ERROR, "
"logging.CRITICAL)\n"
"    logging.basicConfig(level=logging.DEBUG,\n"
"                        format='%(asctime)-15s %(name)-5s %(levelname)-8s "
"IP: %(ip)-15s User: %(user)-8s %(message)s')\n"
"    a1 = logging.getLogger('a.b.c')\n"
"    a2 = logging.getLogger('d.e.f')\n"
"\n"
"    f = ContextFilter()\n"
"    a1.addFilter(f)\n"
"    a2.addFilter(f)\n"
"    a1.debug('A debug message')\n"
"    a1.info('An info message with %s', 'some parameters')\n"
"    for x in range(10):\n"
"        lvl = choice(levels)\n"
"        lvlname = logging.getLevelName(lvl)\n"
"        a2.log(lvl, 'A message at %s level with %d %s', lvlname, 2, "
"'parameters')"
msgstr ""

#: howto/logging-cookbook.rst:984
msgid "which, when run, produces something like:"
msgstr ""

#: howto/logging-cookbook.rst:986
msgid ""
"2010-09-06 22:38:15,292 a.b.c DEBUG    IP: 123.231.231.123 User: fred     A "
"debug message\n"
"2010-09-06 22:38:15,300 a.b.c INFO     IP: 192.168.0.1     User: sheila   An "
"info message with some parameters\n"
"2010-09-06 22:38:15,300 d.e.f CRITICAL IP: 127.0.0.1       User: sheila   A "
"message at CRITICAL level with 2 parameters\n"
"2010-09-06 22:38:15,300 d.e.f ERROR    IP: 127.0.0.1       User: jim      A "
"message at ERROR level with 2 parameters\n"
"2010-09-06 22:38:15,300 d.e.f DEBUG    IP: 127.0.0.1       User: sheila   A "
"message at DEBUG level with 2 parameters\n"
"2010-09-06 22:38:15,300 d.e.f ERROR    IP: 123.231.231.123 User: fred     A "
"message at ERROR level with 2 parameters\n"
"2010-09-06 22:38:15,300 d.e.f CRITICAL IP: 192.168.0.1     User: jim      A "
"message at CRITICAL level with 2 parameters\n"
"2010-09-06 22:38:15,300 d.e.f CRITICAL IP: 127.0.0.1       User: sheila   A "
"message at CRITICAL level with 2 parameters\n"
"2010-09-06 22:38:15,300 d.e.f DEBUG    IP: 192.168.0.1     User: jim      A "
"message at DEBUG level with 2 parameters\n"
"2010-09-06 22:38:15,301 d.e.f ERROR    IP: 127.0.0.1       User: sheila   A "
"message at ERROR level with 2 parameters\n"
"2010-09-06 22:38:15,301 d.e.f DEBUG    IP: 123.231.231.123 User: fred     A "
"message at DEBUG level with 2 parameters\n"
"2010-09-06 22:38:15,301 d.e.f INFO     IP: 123.231.231.123 User: fred     A "
"message at INFO level with 2 parameters"
msgstr ""

#: howto/logging-cookbook.rst:1002
msgid "Use of ``contextvars``"
msgstr ""

#: howto/logging-cookbook.rst:1004
msgid ""
"Since Python 3.7, the :mod:`contextvars` module has provided context-local "
"storage which works for both :mod:`threading` and :mod:`asyncio` processing "
"needs. This type of storage may thus be generally preferable to thread-"
"locals. The following example shows how, in a multi-threaded environment, "
"logs can populated with contextual information such as, for example, request "
"attributes handled by web applications."
msgstr ""

#: howto/logging-cookbook.rst:1010
msgid ""
"For the purposes of illustration, say that you have different web "
"applications, each independent of the other but running in the same Python "
"process and using a library common to them. How can each of these "
"applications have their own log, where all logging messages from the library "
"(and other request processing code) are directed to the appropriate "
"application's log file, while including in the log additional contextual "
"information such as client IP, HTTP request method and client username?"
msgstr ""

#: howto/logging-cookbook.rst:1017
msgid "Let's assume that the library can be simulated by the following code:"
msgstr ""

#: howto/logging-cookbook.rst:1019
msgid ""
"# webapplib.py\n"
"import logging\n"
"import time\n"
"\n"
"logger = logging.getLogger(__name__)\n"
"\n"
"def useful():\n"
"    # Just a representative event logged from the library\n"
"    logger.debug('Hello from webapplib!')\n"
"    # Just sleep for a bit so other threads get to run\n"
"    time.sleep(0.01)"
msgstr ""

#: howto/logging-cookbook.rst:1033
msgid ""
"We can simulate the multiple web applications by means of two simple "
"classes, ``Request`` and ``WebApp``. These simulate how real threaded web "
"applications work - each request is handled by a thread:"
msgstr ""

#: howto/logging-cookbook.rst:1037
msgid ""
"# main.py\n"
"import argparse\n"
"from contextvars import ContextVar\n"
"import logging\n"
"import os\n"
"from random import choice\n"
"import threading\n"
"import webapplib\n"
"\n"
"logger = logging.getLogger(__name__)\n"
"root = logging.getLogger()\n"
"root.setLevel(logging.DEBUG)\n"
"\n"
"class Request:\n"
"    \"\"\"\n"
"    A simple dummy request class which just holds dummy HTTP request "
"method,\n"
"    client IP address and client username\n"
"    \"\"\"\n"
"    def __init__(self, method, ip, user):\n"
"        self.method = method\n"
"        self.ip = ip\n"
"        self.user = user\n"
"\n"
"# A dummy set of requests which will be used in the simulation - we'll just "
"pick\n"
"# from this list randomly. Note that all GET requests are from 192.168.2."
"XXX\n"
"# addresses, whereas POST requests are from 192.16.3.XXX addresses. Three "
"users\n"
"# are represented in the sample requests.\n"
"\n"
"REQUESTS = [\n"
"    Request('GET', '192.168.2.20', 'jim'),\n"
"    Request('POST', '192.168.3.20', 'fred'),\n"
"    Request('GET', '192.168.2.21', 'sheila'),\n"
"    Request('POST', '192.168.3.21', 'jim'),\n"
"    Request('GET', '192.168.2.22', 'fred'),\n"
"    Request('POST', '192.168.3.22', 'sheila'),\n"
"]\n"
"\n"
"# Note that the format string includes references to request context "
"information\n"
"# such as HTTP method, client IP and username\n"
"\n"
"formatter = logging.Formatter('%(threadName)-11s %(appName)s %(name)-9s "
"%(user)-6s %(ip)s %(method)-4s %(message)s')\n"
"\n"
"# Create our context variables. These will be filled at the start of "
"request\n"
"# processing, and used in the logging that happens during that processing\n"
"\n"
"ctx_request = ContextVar('request')\n"
"ctx_appname = ContextVar('appname')\n"
"\n"
"class InjectingFilter(logging.Filter):\n"
"    \"\"\"\n"
"    A filter which injects context-specific information into logs and "
"ensures\n"
"    that only information for a specific webapp is included in its log\n"
"    \"\"\"\n"
"    def __init__(self, app):\n"
"        self.app = app\n"
"\n"
"    def filter(self, record):\n"
"        request = ctx_request.get()\n"
"        record.method = request.method\n"
"        record.ip = request.ip\n"
"        record.user = request.user\n"
"        record.appName = appName = ctx_appname.get()\n"
"        return appName == self.app.name\n"
"\n"
"class WebApp:\n"
"    \"\"\"\n"
"    A dummy web application class which has its own handler and filter for "
"a\n"
"    webapp-specific log.\n"
"    \"\"\"\n"
"    def __init__(self, name):\n"
"        self.name = name\n"
"        handler = logging.FileHandler(name + '.log', 'w')\n"
"        f = InjectingFilter(self)\n"
"        handler.setFormatter(formatter)\n"
"        handler.addFilter(f)\n"
"        root.addHandler(handler)\n"
"        self.num_requests = 0\n"
"\n"
"    def process_request(self, request):\n"
"        \"\"\"\n"
"        This is the dummy method for processing a request. It's called on a\n"
"        different thread for every request. We store the context information "
"into\n"
"        the context vars before doing anything else.\n"
"        \"\"\"\n"
"        ctx_request.set(request)\n"
"        ctx_appname.set(self.name)\n"
"        self.num_requests += 1\n"
"        logger.debug('Request processing started')\n"
"        webapplib.useful()\n"
"        logger.debug('Request processing finished')\n"
"\n"
"def main():\n"
"    fn = os.path.splitext(os.path.basename(__file__))[0]\n"
"    adhf = argparse.ArgumentDefaultsHelpFormatter\n"
"    ap = argparse.ArgumentParser(formatter_class=adhf, prog=fn,\n"
"                                 description='Simulate a couple of web '\n"
"                                             'applications handling some '\n"
"                                             'requests, showing how request "
"'\n"
"                                             'context can be used to '\n"
"                                             'populate logs')\n"
"    aa = ap.add_argument\n"
"    aa('--count', '-c', type=int, default=100, help='How many requests to "
"simulate')\n"
"    options = ap.parse_args()\n"
"\n"
"    # Create the dummy webapps and put them in a list which we can use to "
"select\n"
"    # from randomly\n"
"    app1 = WebApp('app1')\n"
"    app2 = WebApp('app2')\n"
"    apps = [app1, app2]\n"
"    threads = []\n"
"    # Add a common handler which will capture all events\n"
"    handler = logging.FileHandler('app.log', 'w')\n"
"    handler.setFormatter(formatter)\n"
"    root.addHandler(handler)\n"
"\n"
"    # Generate calls to process requests\n"
"    for i in range(options.count):\n"
"        try:\n"
"            # Pick an app at random and a request for it to process\n"
"            app = choice(apps)\n"
"            request = choice(REQUESTS)\n"
"            # Process the request in its own thread\n"
"            t = threading.Thread(target=app.process_request, "
"args=(request,))\n"
"            threads.append(t)\n"
"            t.start()\n"
"        except KeyboardInterrupt:\n"
"            break\n"
"\n"
"    # Wait for the threads to terminate\n"
"    for t in threads:\n"
"        t.join()\n"
"\n"
"    for app in apps:\n"
"        print('%s processed %s requests' % (app.name, app.num_requests))\n"
"\n"
"if __name__ == '__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:1177
msgid ""
"If you run the above, you should find that roughly half the requests go "
"into :file:`app1.log` and the rest into :file:`app2.log`, and the all the "
"requests are logged to :file:`app.log`. Each webapp-specific log will "
"contain only log entries for only that webapp, and the request information "
"will be displayed consistently in the log (i.e. the information in each "
"dummy request will always appear together in a log line). This is "
"illustrated by the following shell output:"
msgstr ""

#: howto/logging-cookbook.rst:1184
msgid ""
"~/logging-contextual-webapp$ python main.py\n"
"app1 processed 51 requests\n"
"app2 processed 49 requests\n"
"~/logging-contextual-webapp$ wc -l *.log\n"
"  153 app1.log\n"
"  147 app2.log\n"
"  300 app.log\n"
"  600 total\n"
"~/logging-contextual-webapp$ head -3 app1.log\n"
"Thread-3 (process_request) app1 __main__  jim    192.168.3.21 POST Request "
"processing started\n"
"Thread-3 (process_request) app1 webapplib jim    192.168.3.21 POST Hello "
"from webapplib!\n"
"Thread-5 (process_request) app1 __main__  jim    192.168.3.21 POST Request "
"processing started\n"
"~/logging-contextual-webapp$ head -3 app2.log\n"
"Thread-1 (process_request) app2 __main__  sheila 192.168.2.21 GET  Request "
"processing started\n"
"Thread-1 (process_request) app2 webapplib sheila 192.168.2.21 GET  Hello "
"from webapplib!\n"
"Thread-2 (process_request) app2 __main__  jim    192.168.2.20 GET  Request "
"processing started\n"
"~/logging-contextual-webapp$ head app.log\n"
"Thread-1 (process_request) app2 __main__  sheila 192.168.2.21 GET  Request "
"processing started\n"
"Thread-1 (process_request) app2 webapplib sheila 192.168.2.21 GET  Hello "
"from webapplib!\n"
"Thread-2 (process_request) app2 __main__  jim    192.168.2.20 GET  Request "
"processing started\n"
"Thread-3 (process_request) app1 __main__  jim    192.168.3.21 POST Request "
"processing started\n"
"Thread-2 (process_request) app2 webapplib jim    192.168.2.20 GET  Hello "
"from webapplib!\n"
"Thread-3 (process_request) app1 webapplib jim    192.168.3.21 POST Hello "
"from webapplib!\n"
"Thread-4 (process_request) app2 __main__  fred   192.168.2.22 GET  Request "
"processing started\n"
"Thread-5 (process_request) app1 __main__  jim    192.168.3.21 POST Request "
"processing started\n"
"Thread-4 (process_request) app2 webapplib fred   192.168.2.22 GET  Hello "
"from webapplib!\n"
"Thread-6 (process_request) app1 __main__  jim    192.168.3.21 POST Request "
"processing started\n"
"~/logging-contextual-webapp$ grep app1 app1.log | wc -l\n"
"153\n"
"~/logging-contextual-webapp$ grep app2 app2.log | wc -l\n"
"147\n"
"~/logging-contextual-webapp$ grep app1 app.log | wc -l\n"
"153\n"
"~/logging-contextual-webapp$ grep app2 app.log | wc -l\n"
"147"
msgstr ""

#: howto/logging-cookbook.rst:1224
msgid "Imparting contextual information in handlers"
msgstr ""

#: howto/logging-cookbook.rst:1226
msgid ""
"Each :class:`~Handler` has its own chain of filters. If you want to add "
"contextual information to a :class:`LogRecord` without leaking it to other "
"handlers, you can use a filter that returns a new :class:`~LogRecord` "
"instead of modifying it in-place, as shown in the following script::"
msgstr ""

#: howto/logging-cookbook.rst:1231
msgid ""
"import copy\n"
"import logging\n"
"\n"
"def filter(record: logging.LogRecord):\n"
"    record = copy.copy(record)\n"
"    record.user = 'jim'\n"
"    return record\n"
"\n"
"if __name__ == '__main__':\n"
"    logger = logging.getLogger()\n"
"    logger.setLevel(logging.INFO)\n"
"    handler = logging.StreamHandler()\n"
"    formatter = logging.Formatter('%(message)s from %(user)-8s')\n"
"    handler.setFormatter(formatter)\n"
"    handler.addFilter(filter)\n"
"    logger.addHandler(handler)\n"
"\n"
"    logger.info('A log message')"
msgstr ""

#: howto/logging-cookbook.rst:1253
msgid "Logging to a single file from multiple processes"
msgstr ""

#: howto/logging-cookbook.rst:1255
msgid ""
"Although logging is thread-safe, and logging to a single file from multiple "
"threads in a single process *is* supported, logging to a single file from "
"*multiple processes* is *not* supported, because there is no standard way to "
"serialize access to a single file across multiple processes in Python. If "
"you need to log to a single file from multiple processes, one way of doing "
"this is to have all the processes log to a :class:`~handlers.SocketHandler`, "
"and have a separate process which implements a socket server which reads "
"from the socket and logs to file. (If you prefer, you can dedicate one "
"thread in one of the existing processes to perform this function.) :ref:"
"`This section <network-logging>` documents this approach in more detail and "
"includes a working socket receiver which can be used as a starting point for "
"you to adapt in your own applications."
msgstr ""

#: howto/logging-cookbook.rst:1268
msgid ""
"You could also write your own handler which uses the :class:"
"`~multiprocessing.Lock` class from the :mod:`multiprocessing` module to "
"serialize access to the file from your processes. The existing :class:"
"`FileHandler` and subclasses do not make use of :mod:`multiprocessing` at "
"present, though they may do so in the future. Note that at present, the :mod:"
"`multiprocessing` module does not provide working lock functionality on all "
"platforms (see https://bugs.python.org/issue3770)."
msgstr ""

#: howto/logging-cookbook.rst:1278
msgid ""
"Alternatively, you can use a ``Queue`` and a :class:`QueueHandler` to send "
"all logging events to one of the processes in your multi-process "
"application. The following example script demonstrates how you can do this; "
"in the example a separate listener process listens for events sent by other "
"processes and logs them according to its own logging configuration. Although "
"the example only demonstrates one way of doing it (for example, you may want "
"to use a listener thread rather than a separate listener process -- the "
"implementation would be analogous) it does allow for completely different "
"logging configurations for the listener and the other processes in your "
"application, and can be used as the basis for code meeting your own specific "
"requirements::"
msgstr ""

#: howto/logging-cookbook.rst:1289
msgid ""
"# You'll need these imports in your own code\n"
"import logging\n"
"import logging.handlers\n"
"import multiprocessing\n"
"\n"
"# Next two import lines for this demo only\n"
"from random import choice, random\n"
"import time\n"
"\n"
"#\n"
"# Because you'll want to define the logging configurations for listener and "
"workers, the\n"
"# listener and worker process functions take a configurer parameter which is "
"a callable\n"
"# for configuring logging for that process. These functions are also passed "
"the queue,\n"
"# which they use for communication.\n"
"#\n"
"# In practice, you can configure the listener however you want, but note "
"that in this\n"
"# simple example, the listener does not apply level or filter logic to "
"received records.\n"
"# In practice, you would probably want to do this logic in the worker "
"processes, to avoid\n"
"# sending events which would be filtered out between processes.\n"
"#\n"
"# The size of the rotated files is made small so you can see the results "
"easily.\n"
"def listener_configurer():\n"
"    root = logging.getLogger()\n"
"    h = logging.handlers.RotatingFileHandler('mptest.log', 'a', 300, 10)\n"
"    f = logging.Formatter('%(asctime)s %(processName)-10s %(name)s "
"%(levelname)-8s %(message)s')\n"
"    h.setFormatter(f)\n"
"    root.addHandler(h)\n"
"\n"
"# This is the listener process top-level loop: wait for logging events\n"
"# (LogRecords)on the queue and handle them, quit when you get a None for a\n"
"# LogRecord.\n"
"def listener_process(queue, configurer):\n"
"    configurer()\n"
"    while True:\n"
"        try:\n"
"            record = queue.get()\n"
"            if record is None:  # We send this as a sentinel to tell the "
"listener to quit.\n"
"                break\n"
"            logger = logging.getLogger(record.name)\n"
"            logger.handle(record)  # No level or filter logic applied - just "
"do it!\n"
"        except Exception:\n"
"            import sys, traceback\n"
"            print('Whoops! Problem:', file=sys.stderr)\n"
"            traceback.print_exc(file=sys.stderr)\n"
"\n"
"# Arrays used for random selections in this demo\n"
"\n"
"LEVELS = [logging.DEBUG, logging.INFO, logging.WARNING,\n"
"          logging.ERROR, logging.CRITICAL]\n"
"\n"
"LOGGERS = ['a.b.c', 'd.e.f']\n"
"\n"
"MESSAGES = [\n"
"    'Random message #1',\n"
"    'Random message #2',\n"
"    'Random message #3',\n"
"]\n"
"\n"
"# The worker configuration is done at the start of the worker process run.\n"
"# Note that on Windows you can't rely on fork semantics, so each process\n"
"# will run the logging configuration code when it starts.\n"
"def worker_configurer(queue):\n"
"    h = logging.handlers.QueueHandler(queue)  # Just the one handler needed\n"
"    root = logging.getLogger()\n"
"    root.addHandler(h)\n"
"    # send all messages, for demo; no other level or filter logic applied.\n"
"    root.setLevel(logging.DEBUG)\n"
"\n"
"# This is the worker process top-level loop, which just logs ten events "
"with\n"
"# random intervening delays before terminating.\n"
"# The print messages are just so you know it's doing something!\n"
"def worker_process(queue, configurer):\n"
"    configurer(queue)\n"
"    name = multiprocessing.current_process().name\n"
"    print('Worker started: %s' % name)\n"
"    for i in range(10):\n"
"        time.sleep(random())\n"
"        logger = logging.getLogger(choice(LOGGERS))\n"
"        level = choice(LEVELS)\n"
"        message = choice(MESSAGES)\n"
"        logger.log(level, message)\n"
"    print('Worker finished: %s' % name)\n"
"\n"
"# Here's where the demo gets orchestrated. Create the queue, create and "
"start\n"
"# the listener, create ten workers and start them, wait for them to finish,\n"
"# then send a None to the queue to tell the listener to finish.\n"
"def main():\n"
"    queue = multiprocessing.Queue(-1)\n"
"    listener = multiprocessing.Process(target=listener_process,\n"
"                                       args=(queue, listener_configurer))\n"
"    listener.start()\n"
"    workers = []\n"
"    for i in range(10):\n"
"        worker = multiprocessing.Process(target=worker_process,\n"
"                                         args=(queue, worker_configurer))\n"
"        workers.append(worker)\n"
"        worker.start()\n"
"    for w in workers:\n"
"        w.join()\n"
"    queue.put_nowait(None)\n"
"    listener.join()\n"
"\n"
"if __name__ == '__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:1394
msgid ""
"A variant of the above script keeps the logging in the main process, in a "
"separate thread::"
msgstr ""

#: howto/logging-cookbook.rst:1397
msgid ""
"import logging\n"
"import logging.config\n"
"import logging.handlers\n"
"from multiprocessing import Process, Queue\n"
"import random\n"
"import threading\n"
"import time\n"
"\n"
"def logger_thread(q):\n"
"    while True:\n"
"        record = q.get()\n"
"        if record is None:\n"
"            break\n"
"        logger = logging.getLogger(record.name)\n"
"        logger.handle(record)\n"
"\n"
"\n"
"def worker_process(q):\n"
"    qh = logging.handlers.QueueHandler(q)\n"
"    root = logging.getLogger()\n"
"    root.setLevel(logging.DEBUG)\n"
"    root.addHandler(qh)\n"
"    levels = [logging.DEBUG, logging.INFO, logging.WARNING, logging.ERROR,\n"
"              logging.CRITICAL]\n"
"    loggers = ['foo', 'foo.bar', 'foo.bar.baz',\n"
"               'spam', 'spam.ham', 'spam.ham.eggs']\n"
"    for i in range(100):\n"
"        lvl = random.choice(levels)\n"
"        logger = logging.getLogger(random.choice(loggers))\n"
"        logger.log(lvl, 'Message no. %d', i)\n"
"\n"
"if __name__ == '__main__':\n"
"    q = Queue()\n"
"    d = {\n"
"        'version': 1,\n"
"        'formatters': {\n"
"            'detailed': {\n"
"                'class': 'logging.Formatter',\n"
"                'format': '%(asctime)s %(name)-15s %(levelname)-8s "
"%(processName)-10s %(message)s'\n"
"            }\n"
"        },\n"
"        'handlers': {\n"
"            'console': {\n"
"                'class': 'logging.StreamHandler',\n"
"                'level': 'INFO',\n"
"            },\n"
"            'file': {\n"
"                'class': 'logging.FileHandler',\n"
"                'filename': 'mplog.log',\n"
"                'mode': 'w',\n"
"                'formatter': 'detailed',\n"
"            },\n"
"            'foofile': {\n"
"                'class': 'logging.FileHandler',\n"
"                'filename': 'mplog-foo.log',\n"
"                'mode': 'w',\n"
"                'formatter': 'detailed',\n"
"            },\n"
"            'errors': {\n"
"                'class': 'logging.FileHandler',\n"
"                'filename': 'mplog-errors.log',\n"
"                'mode': 'w',\n"
"                'level': 'ERROR',\n"
"                'formatter': 'detailed',\n"
"            },\n"
"        },\n"
"        'loggers': {\n"
"            'foo': {\n"
"                'handlers': ['foofile']\n"
"            }\n"
"        },\n"
"        'root': {\n"
"            'level': 'DEBUG',\n"
"            'handlers': ['console', 'file', 'errors']\n"
"        },\n"
"    }\n"
"    workers = []\n"
"    for i in range(5):\n"
"        wp = Process(target=worker_process, name='worker %d' % (i + 1), "
"args=(q,))\n"
"        workers.append(wp)\n"
"        wp.start()\n"
"    logging.config.dictConfig(d)\n"
"    lp = threading.Thread(target=logger_thread, args=(q,))\n"
"    lp.start()\n"
"    # At this point, the main process could do some useful work of its own\n"
"    # Once it's done that, it can wait for the workers to terminate...\n"
"    for wp in workers:\n"
"        wp.join()\n"
"    # And now tell the logging thread to finish up, too\n"
"    q.put(None)\n"
"    lp.join()"
msgstr ""

#: howto/logging-cookbook.rst:1489
msgid ""
"This variant shows how you can e.g. apply configuration for particular "
"loggers - e.g. the ``foo`` logger has a special handler which stores all "
"events in the ``foo`` subsystem in a file ``mplog-foo.log``. This will be "
"used by the logging machinery in the main process (even though the logging "
"events are generated in the worker processes) to direct the messages to the "
"appropriate destinations."
msgstr ""

#: howto/logging-cookbook.rst:1496
msgid "Using concurrent.futures.ProcessPoolExecutor"
msgstr ""

#: howto/logging-cookbook.rst:1498
msgid ""
"If you want to use :class:`concurrent.futures.ProcessPoolExecutor` to start "
"your worker processes, you need to create the queue slightly differently. "
"Instead of"
msgstr ""

#: howto/logging-cookbook.rst:1502
msgid "queue = multiprocessing.Queue(-1)"
msgstr ""

#: howto/logging-cookbook.rst:1506
msgid "you should use"
msgstr ""

#: howto/logging-cookbook.rst:1508
msgid ""
"queue = multiprocessing.Manager().Queue(-1)  # also works with the examples "
"above"
msgstr ""

#: howto/logging-cookbook.rst:1512
msgid "and you can then replace the worker creation from this::"
msgstr ""

#: howto/logging-cookbook.rst:1514
msgid ""
"workers = []\n"
"for i in range(10):\n"
"    worker = multiprocessing.Process(target=worker_process,\n"
"                                     args=(queue, worker_configurer))\n"
"    workers.append(worker)\n"
"    worker.start()\n"
"for w in workers:\n"
"    w.join()"
msgstr ""

#: howto/logging-cookbook.rst:1523
msgid "to this (remembering to first import :mod:`concurrent.futures`)::"
msgstr ""

#: howto/logging-cookbook.rst:1525
msgid ""
"with concurrent.futures.ProcessPoolExecutor(max_workers=10) as executor:\n"
"    for i in range(10):\n"
"        executor.submit(worker_process, queue, worker_configurer)"
msgstr ""

#: howto/logging-cookbook.rst:1530
msgid "Deploying Web applications using Gunicorn and uWSGI"
msgstr ""

#: howto/logging-cookbook.rst:1532
msgid ""
"When deploying Web applications using `Gunicorn <https://gunicorn.org/>`_ or "
"`uWSGI <https://uwsgi-docs.readthedocs.io/en/latest/>`_ (or similar), "
"multiple worker processes are created to handle client requests. In such "
"environments, avoid creating file-based handlers directly in your web "
"application. Instead, use a :class:`SocketHandler` to log from the web "
"application to a listener in a separate process. This can be set up using a "
"process management tool such as Supervisor - see `Running a logging socket "
"listener in production`_ for more details."
msgstr ""

#: howto/logging-cookbook.rst:1542
msgid "Using file rotation"
msgstr ""

#: howto/logging-cookbook.rst:1547
msgid ""
"Sometimes you want to let a log file grow to a certain size, then open a new "
"file and log to that. You may want to keep a certain number of these files, "
"and when that many files have been created, rotate the files so that the "
"number of files and the size of the files both remain bounded. For this "
"usage pattern, the logging package provides a :class:`RotatingFileHandler`::"
msgstr ""

#: howto/logging-cookbook.rst:1553
msgid ""
"import glob\n"
"import logging\n"
"import logging.handlers\n"
"\n"
"LOG_FILENAME = 'logging_rotatingfile_example.out'\n"
"\n"
"# Set up a specific logger with our desired output level\n"
"my_logger = logging.getLogger('MyLogger')\n"
"my_logger.setLevel(logging.DEBUG)\n"
"\n"
"# Add the log message handler to the logger\n"
"handler = logging.handlers.RotatingFileHandler(\n"
"              LOG_FILENAME, maxBytes=20, backupCount=5)\n"
"\n"
"my_logger.addHandler(handler)\n"
"\n"
"# Log some messages\n"
"for i in range(20):\n"
"    my_logger.debug('i = %d' % i)\n"
"\n"
"# See what files are created\n"
"logfiles = glob.glob('%s*' % LOG_FILENAME)\n"
"\n"
"for filename in logfiles:\n"
"    print(filename)"
msgstr ""

#: howto/logging-cookbook.rst:1579
msgid ""
"The result should be 6 separate files, each with part of the log history for "
"the application:"
msgstr ""

#: howto/logging-cookbook.rst:1582
msgid ""
"logging_rotatingfile_example.out\n"
"logging_rotatingfile_example.out.1\n"
"logging_rotatingfile_example.out.2\n"
"logging_rotatingfile_example.out.3\n"
"logging_rotatingfile_example.out.4\n"
"logging_rotatingfile_example.out.5"
msgstr ""

#: howto/logging-cookbook.rst:1591
msgid ""
"The most current file is always :file:`logging_rotatingfile_example.out`, "
"and each time it reaches the size limit it is renamed with the suffix "
"``.1``. Each of the existing backup files is renamed to increment the suffix "
"(``.1`` becomes ``.2``, etc.)  and the ``.6`` file is erased."
msgstr ""

#: howto/logging-cookbook.rst:1596
msgid ""
"Obviously this example sets the log length much too small as an extreme "
"example.  You would want to set *maxBytes* to an appropriate value."
msgstr ""

#: howto/logging-cookbook.rst:1604
msgid "Use of alternative formatting styles"
msgstr ""

#: howto/logging-cookbook.rst:1606
msgid ""
"When logging was added to the Python standard library, the only way of "
"formatting messages with variable content was to use the %-formatting "
"method. Since then, Python has gained two new formatting approaches: :class:"
"`string.Template` (added in Python 2.4) and :meth:`str.format` (added in "
"Python 2.6)."
msgstr ""

#: howto/logging-cookbook.rst:1612
msgid ""
"Logging (as of 3.2) provides improved support for these two additional "
"formatting styles. The :class:`Formatter` class been enhanced to take an "
"additional, optional keyword parameter named ``style``. This defaults to "
"``'%'``, but other possible values are ``'{'`` and ``'$'``, which correspond "
"to the other two formatting styles. Backwards compatibility is maintained by "
"default (as you would expect), but by explicitly specifying a style "
"parameter, you get the ability to specify format strings which work with :"
"meth:`str.format` or :class:`string.Template`. Here's an example console "
"session to show the possibilities:"
msgstr ""

#: howto/logging-cookbook.rst:1622
msgid ""
">>> import logging\n"
">>> root = logging.getLogger()\n"
">>> root.setLevel(logging.DEBUG)\n"
">>> handler = logging.StreamHandler()\n"
">>> bf = logging.Formatter('{asctime} {name} {levelname:8s} {message}',\n"
"...                        style='{')\n"
">>> handler.setFormatter(bf)\n"
">>> root.addHandler(handler)\n"
">>> logger = logging.getLogger('foo.bar')\n"
">>> logger.debug('This is a DEBUG message')\n"
"2010-10-28 15:11:55,341 foo.bar DEBUG    This is a DEBUG message\n"
">>> logger.critical('This is a CRITICAL message')\n"
"2010-10-28 15:12:11,526 foo.bar CRITICAL This is a CRITICAL message\n"
">>> df = logging.Formatter('$asctime $name ${levelname} $message',\n"
"...                        style='$')\n"
">>> handler.setFormatter(df)\n"
">>> logger.debug('This is a DEBUG message')\n"
"2010-10-28 15:13:06,924 foo.bar DEBUG This is a DEBUG message\n"
">>> logger.critical('This is a CRITICAL message')\n"
"2010-10-28 15:13:11,494 foo.bar CRITICAL This is a CRITICAL message\n"
">>>"
msgstr ""

#: howto/logging-cookbook.rst:1646
msgid ""
"Note that the formatting of logging messages for final output to logs is "
"completely independent of how an individual logging message is constructed. "
"That can still use %-formatting, as shown here::"
msgstr ""

#: howto/logging-cookbook.rst:1650
msgid ""
">>> logger.error('This is an%s %s %s', 'other,', 'ERROR,', 'message')\n"
"2010-10-28 15:19:29,833 foo.bar ERROR This is another, ERROR, message\n"
">>>"
msgstr ""

#: howto/logging-cookbook.rst:1654
msgid ""
"Logging calls (``logger.debug()``, ``logger.info()`` etc.) only take "
"positional parameters for the actual logging message itself, with keyword "
"parameters used only for determining options for how to handle the actual "
"logging call (e.g. the ``exc_info`` keyword parameter to indicate that "
"traceback information should be logged, or the ``extra`` keyword parameter "
"to indicate additional contextual information to be added to the log). So "
"you cannot directly make logging calls using :meth:`str.format` or :class:"
"`string.Template` syntax, because internally the logging package uses %-"
"formatting to merge the format string and the variable arguments. There "
"would be no changing this while preserving backward compatibility, since all "
"logging calls which are out there in existing code will be using %-format "
"strings."
msgstr ""

#: howto/logging-cookbook.rst:1667
msgid ""
"There is, however, a way that you can use {}- and $- formatting to construct "
"your individual log messages. Recall that for a message you can use an "
"arbitrary object as a message format string, and that the logging package "
"will call ``str()`` on that object to get the actual format string. Consider "
"the following two classes::"
msgstr ""

#: howto/logging-cookbook.rst:1673 howto/logging-cookbook.rst:2761
msgid ""
"class BraceMessage:\n"
"    def __init__(self, fmt, /, *args, **kwargs):\n"
"        self.fmt = fmt\n"
"        self.args = args\n"
"        self.kwargs = kwargs\n"
"\n"
"    def __str__(self):\n"
"        return self.fmt.format(*self.args, **self.kwargs)\n"
"\n"
"class DollarMessage:\n"
"    def __init__(self, fmt, /, **kwargs):\n"
"        self.fmt = fmt\n"
"        self.kwargs = kwargs\n"
"\n"
"    def __str__(self):\n"
"        from string import Template\n"
"        return Template(self.fmt).substitute(**self.kwargs)"
msgstr ""

#: howto/logging-cookbook.rst:1691
msgid ""
"Either of these can be used in place of a format string, to allow {}- or $-"
"formatting to be used to build the actual \"message\" part which appears in "
"the formatted log output in place of \"%(message)s\" or \"{message}\" or "
"\"$message\". It's a little unwieldy to use the class names whenever you "
"want to log something, but it's quite palatable if you use an alias such as "
"__ (double underscore --- not to be confused with _, the single underscore "
"used as a synonym/alias for :func:`gettext.gettext` or its brethren)."
msgstr ""

#: howto/logging-cookbook.rst:1699
msgid ""
"The above classes are not included in Python, though they're easy enough to "
"copy and paste into your own code. They can be used as follows (assuming "
"that they're declared in a module called ``wherever``):"
msgstr ""

#: howto/logging-cookbook.rst:1703
msgid ""
">>> from wherever import BraceMessage as __\n"
">>> print(__('Message with {0} {name}', 2, name='placeholders'))\n"
"Message with 2 placeholders\n"
">>> class Point: pass\n"
"...\n"
">>> p = Point()\n"
">>> p.x = 0.5\n"
">>> p.y = 0.5\n"
">>> print(__('Message with coordinates: ({point.x:.2f}, {point.y:.2f})',\n"
"...       point=p))\n"
"Message with coordinates: (0.50, 0.50)\n"
">>> from wherever import DollarMessage as __\n"
">>> print(__('Message with $num $what', num=2, what='placeholders'))\n"
"Message with 2 placeholders\n"
">>>"
msgstr ""

#: howto/logging-cookbook.rst:1721
msgid ""
"While the above examples use ``print()`` to show how the formatting works, "
"you would of course use ``logger.debug()`` or similar to actually log using "
"this approach."
msgstr ""

#: howto/logging-cookbook.rst:1725
msgid ""
"One thing to note is that you pay no significant performance penalty with "
"this approach: the actual formatting happens not when you make the logging "
"call, but when (and if) the logged message is actually about to be output to "
"a log by a handler. So the only slightly unusual thing which might trip you "
"up is that the parentheses go around the format string and the arguments, "
"not just the format string. That's because the __ notation is just syntax "
"sugar for a constructor call to one of the :samp:`{XXX}Message` classes."
msgstr ""

#: howto/logging-cookbook.rst:1733
msgid ""
"If you prefer, you can use a :class:`LoggerAdapter` to achieve a similar "
"effect to the above, as in the following example::"
msgstr ""

#: howto/logging-cookbook.rst:1736
msgid ""
"import logging\n"
"\n"
"class Message:\n"
"    def __init__(self, fmt, args):\n"
"        self.fmt = fmt\n"
"        self.args = args\n"
"\n"
"    def __str__(self):\n"
"        return self.fmt.format(*self.args)\n"
"\n"
"class StyleAdapter(logging.LoggerAdapter):\n"
"    def log(self, level, msg, /, *args, stacklevel=1, **kwargs):\n"
"        if self.isEnabledFor(level):\n"
"            msg, kwargs = self.process(msg, kwargs)\n"
"            self.logger.log(level, Message(msg, args), **kwargs,\n"
"                            stacklevel=stacklevel+1)\n"
"\n"
"logger = StyleAdapter(logging.getLogger(__name__))\n"
"\n"
"def main():\n"
"    logger.debug('Hello, {}', 'world!')\n"
"\n"
"if __name__ == '__main__':\n"
"    logging.basicConfig(level=logging.DEBUG)\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:1762
msgid ""
"The above script should log the message ``Hello, world!`` when run with "
"Python 3.8 or later."
msgstr ""

#: howto/logging-cookbook.rst:1771
msgid "Customizing ``LogRecord``"
msgstr ""

#: howto/logging-cookbook.rst:1773
msgid ""
"Every logging event is represented by a :class:`LogRecord` instance. When an "
"event is logged and not filtered out by a logger's level, a :class:"
"`LogRecord` is created, populated with information about the event and then "
"passed to the handlers for that logger (and its ancestors, up to and "
"including the logger where further propagation up the hierarchy is "
"disabled). Before Python 3.2, there were only two places where this creation "
"was done:"
msgstr ""

#: howto/logging-cookbook.rst:1780
msgid ""
":meth:`Logger.makeRecord`, which is called in the normal process of logging "
"an event. This invoked :class:`LogRecord` directly to create an instance."
msgstr ""

#: howto/logging-cookbook.rst:1783
msgid ""
":func:`makeLogRecord`, which is called with a dictionary containing "
"attributes to be added to the LogRecord. This is typically invoked when a "
"suitable dictionary has been received over the network (e.g. in pickle form "
"via a :class:`~handlers.SocketHandler`, or in JSON form via an :class:"
"`~handlers.HTTPHandler`)."
msgstr ""

#: howto/logging-cookbook.rst:1789
msgid ""
"This has usually meant that if you need to do anything special with a :class:"
"`LogRecord`, you've had to do one of the following."
msgstr ""

#: howto/logging-cookbook.rst:1792
msgid ""
"Create your own :class:`Logger` subclass, which overrides :meth:`Logger."
"makeRecord`, and set it using :func:`~logging.setLoggerClass` before any "
"loggers that you care about are instantiated."
msgstr ""

#: howto/logging-cookbook.rst:1795
msgid ""
"Add a :class:`Filter` to a logger or handler, which does the necessary "
"special manipulation you need when its :meth:`~Filter.filter` method is "
"called."
msgstr ""

#: howto/logging-cookbook.rst:1799
msgid ""
"The first approach would be a little unwieldy in the scenario where (say) "
"several different libraries wanted to do different things. Each would "
"attempt to set its own :class:`Logger` subclass, and the one which did this "
"last would win."
msgstr ""

#: howto/logging-cookbook.rst:1804
msgid ""
"The second approach works reasonably well for many cases, but does not allow "
"you to e.g. use a specialized subclass of :class:`LogRecord`. Library "
"developers can set a suitable filter on their loggers, but they would have "
"to remember to do this every time they introduced a new logger (which they "
"would do simply by adding new packages or modules and doing ::"
msgstr ""

#: howto/logging-cookbook.rst:1810
msgid "logger = logging.getLogger(__name__)"
msgstr ""

#: howto/logging-cookbook.rst:1812
msgid ""
"at module level). It's probably one too many things to think about. "
"Developers could also add the filter to a :class:`~logging.NullHandler` "
"attached to their top-level logger, but this would not be invoked if an "
"application developer attached a handler to a lower-level library logger --- "
"so output from that handler would not reflect the intentions of the library "
"developer."
msgstr ""

#: howto/logging-cookbook.rst:1818
msgid ""
"In Python 3.2 and later, :class:`~logging.LogRecord` creation is done "
"through a factory, which you can specify. The factory is just a callable you "
"can set with :func:`~logging.setLogRecordFactory`, and interrogate with :"
"func:`~logging.getLogRecordFactory`. The factory is invoked with the same "
"signature as the :class:`~logging.LogRecord` constructor, as :class:"
"`LogRecord` is the default setting for the factory."
msgstr ""

#: howto/logging-cookbook.rst:1825
msgid ""
"This approach allows a custom factory to control all aspects of LogRecord "
"creation. For example, you could return a subclass, or just add some "
"additional attributes to the record once created, using a pattern similar to "
"this::"
msgstr ""

#: howto/logging-cookbook.rst:1829
msgid ""
"old_factory = logging.getLogRecordFactory()\n"
"\n"
"def record_factory(*args, **kwargs):\n"
"    record = old_factory(*args, **kwargs)\n"
"    record.custom_attribute = 0xdecafbad\n"
"    return record\n"
"\n"
"logging.setLogRecordFactory(record_factory)"
msgstr ""

#: howto/logging-cookbook.rst:1838
msgid ""
"This pattern allows different libraries to chain factories together, and as "
"long as they don't overwrite each other's attributes or unintentionally "
"overwrite the attributes provided as standard, there should be no surprises. "
"However, it should be borne in mind that each link in the chain adds run-"
"time overhead to all logging operations, and the technique should only be "
"used when the use of a :class:`Filter` does not provide the desired result."
msgstr ""

#: howto/logging-cookbook.rst:1850
msgid "Subclassing QueueHandler and QueueListener- a ZeroMQ example"
msgstr ""

#: howto/logging-cookbook.rst:1853 howto/logging-cookbook.rst:1986
msgid "Subclass ``QueueHandler``"
msgstr ""

#: howto/logging-cookbook.rst:1855
msgid ""
"You can use a :class:`QueueHandler` subclass to send messages to other kinds "
"of queues, for example a ZeroMQ 'publish' socket. In the example below,the "
"socket is created separately and passed to the handler (as its 'queue')::"
msgstr ""

#: howto/logging-cookbook.rst:1859
msgid ""
"import zmq   # using pyzmq, the Python binding for ZeroMQ\n"
"import json  # for serializing records portably\n"
"\n"
"ctx = zmq.Context()\n"
"sock = zmq.Socket(ctx, zmq.PUB)  # or zmq.PUSH, or other suitable value\n"
"sock.bind('tcp://*:5556')        # or wherever\n"
"\n"
"class ZeroMQSocketHandler(QueueHandler):\n"
"    def enqueue(self, record):\n"
"        self.queue.send_json(record.__dict__)\n"
"\n"
"\n"
"handler = ZeroMQSocketHandler(sock)"
msgstr ""

#: howto/logging-cookbook.rst:1874
msgid ""
"Of course there are other ways of organizing this, for example passing in "
"the data needed by the handler to create the socket::"
msgstr ""

#: howto/logging-cookbook.rst:1877
msgid ""
"class ZeroMQSocketHandler(QueueHandler):\n"
"    def __init__(self, uri, socktype=zmq.PUB, ctx=None):\n"
"        self.ctx = ctx or zmq.Context()\n"
"        socket = zmq.Socket(self.ctx, socktype)\n"
"        socket.bind(uri)\n"
"        super().__init__(socket)\n"
"\n"
"    def enqueue(self, record):\n"
"        self.queue.send_json(record.__dict__)\n"
"\n"
"    def close(self):\n"
"        self.queue.close()"
msgstr ""

#: howto/logging-cookbook.rst:1892 howto/logging-cookbook.rst:1922
msgid "Subclass ``QueueListener``"
msgstr ""

#: howto/logging-cookbook.rst:1894
msgid ""
"You can also subclass :class:`QueueListener` to get messages from other "
"kinds of queues, for example a ZeroMQ 'subscribe' socket. Here's an example::"
msgstr ""

#: howto/logging-cookbook.rst:1897
msgid ""
"class ZeroMQSocketListener(QueueListener):\n"
"    def __init__(self, uri, /, *handlers, **kwargs):\n"
"        self.ctx = kwargs.get('ctx') or zmq.Context()\n"
"        socket = zmq.Socket(self.ctx, zmq.SUB)\n"
"        socket.setsockopt_string(zmq.SUBSCRIBE, '')  # subscribe to "
"everything\n"
"        socket.connect(uri)\n"
"        super().__init__(socket, *handlers, **kwargs)\n"
"\n"
"    def dequeue(self):\n"
"        msg = self.queue.recv_json()\n"
"        return logging.makeLogRecord(msg)"
msgstr ""

#: howto/logging-cookbook.rst:1912
msgid "Subclassing QueueHandler and QueueListener- a ``pynng`` example"
msgstr ""

#: howto/logging-cookbook.rst:1914
msgid ""
"In a similar way to the above section, we can implement a listener and "
"handler using :pypi:`pynng`, which is a Python binding to `NNG <https://nng."
"nanomsg.org/>`_, billed as a spiritual successor to ZeroMQ. The following "
"snippets illustrate -- you can test them in an environment which has "
"``pynng`` installed. Just for variety, we present the listener first."
msgstr ""

#: howto/logging-cookbook.rst:1924
msgid ""
"# listener.py\n"
"import json\n"
"import logging\n"
"import logging.handlers\n"
"\n"
"import pynng\n"
"\n"
"DEFAULT_ADDR = \"tcp://localhost:13232\"\n"
"\n"
"interrupted = False\n"
"\n"
"class NNGSocketListener(logging.handlers.QueueListener):\n"
"\n"
"    def __init__(self, uri, /, *handlers, **kwargs):\n"
"        # Have a timeout for interruptability, and open a\n"
"        # subscriber socket\n"
"        socket = pynng.Sub0(listen=uri, recv_timeout=500)\n"
"        # The b'' subscription matches all topics\n"
"        topics = kwargs.pop('topics', None) or b''\n"
"        socket.subscribe(topics)\n"
"        # We treat the socket as a queue\n"
"        super().__init__(socket, *handlers, **kwargs)\n"
"\n"
"    def dequeue(self, block):\n"
"        data = None\n"
"        # Keep looping while not interrupted and no data received over the\n"
"        # socket\n"
"        while not interrupted:\n"
"            try:\n"
"                data = self.queue.recv(block=block)\n"
"                break\n"
"            except pynng.Timeout:\n"
"                pass\n"
"            except pynng.Closed:  # sometimes happens when you hit Ctrl-C\n"
"                break\n"
"        if data is None:\n"
"            return None\n"
"        # Get the logging event sent from a publisher\n"
"        event = json.loads(data.decode('utf-8'))\n"
"        return logging.makeLogRecord(event)\n"
"\n"
"    def enqueue_sentinel(self):\n"
"        # Not used in this implementation, as the socket isn't really a\n"
"        # queue\n"
"        pass\n"
"\n"
"logging.getLogger('pynng').propagate = False\n"
"listener = NNGSocketListener(DEFAULT_ADDR, logging.StreamHandler(), "
"topics=b'')\n"
"listener.start()\n"
"print('Press Ctrl-C to stop.')\n"
"try:\n"
"    while True:\n"
"        pass\n"
"except KeyboardInterrupt:\n"
"    interrupted = True\n"
"finally:\n"
"    listener.stop()"
msgstr ""

#: howto/logging-cookbook.rst:1990
msgid ""
"# sender.py\n"
"import json\n"
"import logging\n"
"import logging.handlers\n"
"import time\n"
"import random\n"
"\n"
"import pynng\n"
"\n"
"DEFAULT_ADDR = \"tcp://localhost:13232\"\n"
"\n"
"class NNGSocketHandler(logging.handlers.QueueHandler):\n"
"\n"
"    def __init__(self, uri):\n"
"        socket = pynng.Pub0(dial=uri, send_timeout=500)\n"
"        super().__init__(socket)\n"
"\n"
"    def enqueue(self, record):\n"
"        # Send the record as UTF-8 encoded JSON\n"
"        d = dict(record.__dict__)\n"
"        data = json.dumps(d)\n"
"        self.queue.send(data.encode('utf-8'))\n"
"\n"
"    def close(self):\n"
"        self.queue.close()\n"
"\n"
"logging.getLogger('pynng').propagate = False\n"
"handler = NNGSocketHandler(DEFAULT_ADDR)\n"
"# Make sure the process ID is in the output\n"
"logging.basicConfig(level=logging.DEBUG,\n"
"                    handlers=[logging.StreamHandler(), handler],\n"
"                    format='%(levelname)-8s %(name)10s %(process)6s "
"%(message)s')\n"
"levels = (logging.DEBUG, logging.INFO, logging.WARNING, logging.ERROR,\n"
"          logging.CRITICAL)\n"
"logger_names = ('myapp', 'myapp.lib1', 'myapp.lib2')\n"
"msgno = 1\n"
"while True:\n"
"    # Just randomly select some loggers and levels and log away\n"
"    level = random.choice(levels)\n"
"    logger = logging.getLogger(random.choice(logger_names))\n"
"    logger.log(level, 'Message no. %5d' % msgno)\n"
"    msgno += 1\n"
"    delay = random.random() * 2 + 0.5\n"
"    time.sleep(delay)"
msgstr ""

#: howto/logging-cookbook.rst:2037
msgid ""
"You can run the above two snippets in separate command shells. If we run the "
"listener in one shell and run the sender in two separate shells, we should "
"see something like the following. In the first sender shell:"
msgstr ""

#: howto/logging-cookbook.rst:2041
msgid ""
"$ python sender.py\n"
"DEBUG         myapp    613 Message no.     1\n"
"WARNING  myapp.lib2    613 Message no.     2\n"
"CRITICAL myapp.lib2    613 Message no.     3\n"
"WARNING  myapp.lib2    613 Message no.     4\n"
"CRITICAL myapp.lib1    613 Message no.     5\n"
"DEBUG         myapp    613 Message no.     6\n"
"CRITICAL myapp.lib1    613 Message no.     7\n"
"INFO     myapp.lib1    613 Message no.     8\n"
"(and so on)"
msgstr ""

#: howto/logging-cookbook.rst:2054
msgid "In the second sender shell:"
msgstr ""

#: howto/logging-cookbook.rst:2056
msgid ""
"$ python sender.py\n"
"INFO     myapp.lib2    657 Message no.     1\n"
"CRITICAL myapp.lib2    657 Message no.     2\n"
"CRITICAL      myapp    657 Message no.     3\n"
"CRITICAL myapp.lib1    657 Message no.     4\n"
"INFO     myapp.lib1    657 Message no.     5\n"
"WARNING  myapp.lib2    657 Message no.     6\n"
"CRITICAL      myapp    657 Message no.     7\n"
"DEBUG    myapp.lib1    657 Message no.     8\n"
"(and so on)"
msgstr ""

#: howto/logging-cookbook.rst:2069
msgid "In the listener shell:"
msgstr ""

#: howto/logging-cookbook.rst:2071
msgid ""
"$ python listener.py\n"
"Press Ctrl-C to stop.\n"
"DEBUG         myapp    613 Message no.     1\n"
"WARNING  myapp.lib2    613 Message no.     2\n"
"INFO     myapp.lib2    657 Message no.     1\n"
"CRITICAL myapp.lib2    613 Message no.     3\n"
"CRITICAL myapp.lib2    657 Message no.     2\n"
"CRITICAL      myapp    657 Message no.     3\n"
"WARNING  myapp.lib2    613 Message no.     4\n"
"CRITICAL myapp.lib1    613 Message no.     5\n"
"CRITICAL myapp.lib1    657 Message no.     4\n"
"INFO     myapp.lib1    657 Message no.     5\n"
"DEBUG         myapp    613 Message no.     6\n"
"WARNING  myapp.lib2    657 Message no.     6\n"
"CRITICAL      myapp    657 Message no.     7\n"
"CRITICAL myapp.lib1    613 Message no.     7\n"
"INFO     myapp.lib1    613 Message no.     8\n"
"DEBUG    myapp.lib1    657 Message no.     8\n"
"(and so on)"
msgstr ""

#: howto/logging-cookbook.rst:2093
msgid ""
"As you can see, the logging from the two sender processes is interleaved in "
"the listener's output."
msgstr ""

#: howto/logging-cookbook.rst:2098
msgid "An example dictionary-based configuration"
msgstr ""

#: howto/logging-cookbook.rst:2100
msgid ""
"Below is an example of a logging configuration dictionary - it's taken from "
"the `documentation on the Django project <https://docs.djangoproject.com/en/"
"stable/topics/logging/#configuring-logging>`_. This dictionary is passed to :"
"func:`~config.dictConfig` to put the configuration into effect::"
msgstr ""

#: howto/logging-cookbook.rst:2104
msgid ""
"LOGGING = {\n"
"    'version': 1,\n"
"    'disable_existing_loggers': False,\n"
"    'formatters': {\n"
"        'verbose': {\n"
"            'format': '{levelname} {asctime} {module} {process:d} {thread:d} "
"{message}',\n"
"            'style': '{',\n"
"        },\n"
"        'simple': {\n"
"            'format': '{levelname} {message}',\n"
"            'style': '{',\n"
"        },\n"
"    },\n"
"    'filters': {\n"
"        'special': {\n"
"            '()': 'project.logging.SpecialFilter',\n"
"            'foo': 'bar',\n"
"        },\n"
"    },\n"
"    'handlers': {\n"
"        'console': {\n"
"            'level': 'INFO',\n"
"            'class': 'logging.StreamHandler',\n"
"            'formatter': 'simple',\n"
"        },\n"
"        'mail_admins': {\n"
"            'level': 'ERROR',\n"
"            'class': 'django.utils.log.AdminEmailHandler',\n"
"            'filters': ['special']\n"
"        }\n"
"    },\n"
"    'loggers': {\n"
"        'django': {\n"
"            'handlers': ['console'],\n"
"            'propagate': True,\n"
"        },\n"
"        'django.request': {\n"
"            'handlers': ['mail_admins'],\n"
"            'level': 'ERROR',\n"
"            'propagate': False,\n"
"        },\n"
"        'myproject.custom': {\n"
"            'handlers': ['console', 'mail_admins'],\n"
"            'level': 'INFO',\n"
"            'filters': ['special']\n"
"        }\n"
"    }\n"
"}"
msgstr ""

#: howto/logging-cookbook.rst:2153
msgid ""
"For more information about this configuration, you can see the `relevant "
"section <https://docs.djangoproject.com/en/stable/topics/logging/"
"#configuring-logging>`_ of the Django documentation."
msgstr ""

#: howto/logging-cookbook.rst:2160
msgid "Using a rotator and namer to customize log rotation processing"
msgstr ""

#: howto/logging-cookbook.rst:2162
msgid ""
"An example of how you can define a namer and rotator is given in the "
"following runnable script, which shows gzip compression of the log file::"
msgstr ""

#: howto/logging-cookbook.rst:2165
msgid ""
"import gzip\n"
"import logging\n"
"import logging.handlers\n"
"import os\n"
"import shutil\n"
"\n"
"def namer(name):\n"
"    return name + \".gz\"\n"
"\n"
"def rotator(source, dest):\n"
"    with open(source, 'rb') as f_in:\n"
"        with gzip.open(dest, 'wb') as f_out:\n"
"            shutil.copyfileobj(f_in, f_out)\n"
"    os.remove(source)\n"
"\n"
"\n"
"rh = logging.handlers.RotatingFileHandler('rotated.log', maxBytes=128, "
"backupCount=5)\n"
"rh.rotator = rotator\n"
"rh.namer = namer\n"
"\n"
"root = logging.getLogger()\n"
"root.setLevel(logging.INFO)\n"
"root.addHandler(rh)\n"
"f = logging.Formatter('%(asctime)s %(message)s')\n"
"rh.setFormatter(f)\n"
"for i in range(1000):\n"
"    root.info(f'Message no. {i + 1}')"
msgstr ""

#: howto/logging-cookbook.rst:2193
msgid ""
"After running this, you will see six new files, five of which are compressed:"
msgstr ""

#: howto/logging-cookbook.rst:2195
msgid ""
"$ ls rotated.log*\n"
"rotated.log       rotated.log.2.gz  rotated.log.4.gz\n"
"rotated.log.1.gz  rotated.log.3.gz  rotated.log.5.gz\n"
"$ zcat rotated.log.1.gz\n"
"2023-01-20 02:28:17,767 Message no. 996\n"
"2023-01-20 02:28:17,767 Message no. 997\n"
"2023-01-20 02:28:17,767 Message no. 998"
msgstr ""

#: howto/logging-cookbook.rst:2206
msgid "A more elaborate multiprocessing example"
msgstr ""

#: howto/logging-cookbook.rst:2208
msgid ""
"The following working example shows how logging can be used with "
"multiprocessing using configuration files. The configurations are fairly "
"simple, but serve to illustrate how more complex ones could be implemented "
"in a real multiprocessing scenario."
msgstr ""

#: howto/logging-cookbook.rst:2213
msgid ""
"In the example, the main process spawns a listener process and some worker "
"processes. Each of the main process, the listener and the workers have three "
"separate configurations (the workers all share the same configuration). We "
"can see logging in the main process, how the workers log to a QueueHandler "
"and how the listener implements a QueueListener and a more complex logging "
"configuration, and arranges to dispatch events received via the queue to the "
"handlers specified in the configuration. Note that these configurations are "
"purely illustrative, but you should be able to adapt this example to your "
"own scenario."
msgstr ""

#: howto/logging-cookbook.rst:2223
msgid ""
"Here's the script - the docstrings and the comments hopefully explain how it "
"works::"
msgstr ""

#: howto/logging-cookbook.rst:2226
msgid ""
"import logging\n"
"import logging.config\n"
"import logging.handlers\n"
"from multiprocessing import Process, Queue, Event, current_process\n"
"import os\n"
"import random\n"
"import time\n"
"\n"
"class MyHandler:\n"
"    \"\"\"\n"
"    A simple handler for logging events. It runs in the listener process "
"and\n"
"    dispatches events to loggers based on the name in the received record,\n"
"    which then get dispatched, by the logging system, to the handlers\n"
"    configured for those loggers.\n"
"    \"\"\"\n"
"\n"
"    def handle(self, record):\n"
"        if record.name == \"root\":\n"
"            logger = logging.getLogger()\n"
"        else:\n"
"            logger = logging.getLogger(record.name)\n"
"\n"
"        if logger.isEnabledFor(record.levelno):\n"
"            # The process name is transformed just to show that it's the "
"listener\n"
"            # doing the logging to files and console\n"
"            record.processName = '%s (for %s)' % (current_process().name, "
"record.processName)\n"
"            logger.handle(record)\n"
"\n"
"def listener_process(q, stop_event, config):\n"
"    \"\"\"\n"
"    This could be done in the main process, but is just done in a separate\n"
"    process for illustrative purposes.\n"
"\n"
"    This initialises logging according to the specified configuration,\n"
"    starts the listener and waits for the main process to signal completion\n"
"    via the event. The listener is then stopped, and the process exits.\n"
"    \"\"\"\n"
"    logging.config.dictConfig(config)\n"
"    listener = logging.handlers.QueueListener(q, MyHandler())\n"
"    listener.start()\n"
"    if os.name == 'posix':\n"
"        # On POSIX, the setup logger will have been configured in the\n"
"        # parent process, but should have been disabled following the\n"
"        # dictConfig call.\n"
"        # On Windows, since fork isn't used, the setup logger won't\n"
"        # exist in the child, so it would be created and the message\n"
"        # would appear - hence the \"if posix\" clause.\n"
"        logger = logging.getLogger('setup')\n"
"        logger.critical('Should not appear, because of disabled "
"logger ...')\n"
"    stop_event.wait()\n"
"    listener.stop()\n"
"\n"
"def worker_process(config):\n"
"    \"\"\"\n"
"    A number of these are spawned for the purpose of illustration. In\n"
"    practice, they could be a heterogeneous bunch of processes rather than\n"
"    ones which are identical to each other.\n"
"\n"
"    This initialises logging according to the specified configuration,\n"
"    and logs a hundred messages with random levels to randomly selected\n"
"    loggers.\n"
"\n"
"    A small sleep is added to allow other processes a chance to run. This\n"
"    is not strictly needed, but it mixes the output from the different\n"
"    processes a bit more than if it's left out.\n"
"    \"\"\"\n"
"    logging.config.dictConfig(config)\n"
"    levels = [logging.DEBUG, logging.INFO, logging.WARNING, logging.ERROR,\n"
"              logging.CRITICAL]\n"
"    loggers = ['foo', 'foo.bar', 'foo.bar.baz',\n"
"               'spam', 'spam.ham', 'spam.ham.eggs']\n"
"    if os.name == 'posix':\n"
"        # On POSIX, the setup logger will have been configured in the\n"
"        # parent process, but should have been disabled following the\n"
"        # dictConfig call.\n"
"        # On Windows, since fork isn't used, the setup logger won't\n"
"        # exist in the child, so it would be created and the message\n"
"        # would appear - hence the \"if posix\" clause.\n"
"        logger = logging.getLogger('setup')\n"
"        logger.critical('Should not appear, because of disabled "
"logger ...')\n"
"    for i in range(100):\n"
"        lvl = random.choice(levels)\n"
"        logger = logging.getLogger(random.choice(loggers))\n"
"        logger.log(lvl, 'Message no. %d', i)\n"
"        time.sleep(0.01)\n"
"\n"
"def main():\n"
"    q = Queue()\n"
"    # The main process gets a simple configuration which prints to the "
"console.\n"
"    config_initial = {\n"
"        'version': 1,\n"
"        'handlers': {\n"
"            'console': {\n"
"                'class': 'logging.StreamHandler',\n"
"                'level': 'INFO'\n"
"            }\n"
"        },\n"
"        'root': {\n"
"            'handlers': ['console'],\n"
"            'level': 'DEBUG'\n"
"        }\n"
"    }\n"
"    # The worker process configuration is just a QueueHandler attached to "
"the\n"
"    # root logger, which allows all messages to be sent to the queue.\n"
"    # We disable existing loggers to disable the \"setup\" logger used in "
"the\n"
"    # parent process. This is needed on POSIX because the logger will\n"
"    # be there in the child following a fork().\n"
"    config_worker = {\n"
"        'version': 1,\n"
"        'disable_existing_loggers': True,\n"
"        'handlers': {\n"
"            'queue': {\n"
"                'class': 'logging.handlers.QueueHandler',\n"
"                'queue': q\n"
"            }\n"
"        },\n"
"        'root': {\n"
"            'handlers': ['queue'],\n"
"            'level': 'DEBUG'\n"
"        }\n"
"    }\n"
"    # The listener process configuration shows that the full flexibility of\n"
"    # logging configuration is available to dispatch events to handlers "
"however\n"
"    # you want.\n"
"    # We disable existing loggers to disable the \"setup\" logger used in "
"the\n"
"    # parent process. This is needed on POSIX because the logger will\n"
"    # be there in the child following a fork().\n"
"    config_listener = {\n"
"        'version': 1,\n"
"        'disable_existing_loggers': True,\n"
"        'formatters': {\n"
"            'detailed': {\n"
"                'class': 'logging.Formatter',\n"
"                'format': '%(asctime)s %(name)-15s %(levelname)-8s "
"%(processName)-10s %(message)s'\n"
"            },\n"
"            'simple': {\n"
"                'class': 'logging.Formatter',\n"
"                'format': '%(name)-15s %(levelname)-8s %(processName)-10s "
"%(message)s'\n"
"            }\n"
"        },\n"
"        'handlers': {\n"
"            'console': {\n"
"                'class': 'logging.StreamHandler',\n"
"                'formatter': 'simple',\n"
"                'level': 'INFO'\n"
"            },\n"
"            'file': {\n"
"                'class': 'logging.FileHandler',\n"
"                'filename': 'mplog.log',\n"
"                'mode': 'w',\n"
"                'formatter': 'detailed'\n"
"            },\n"
"            'foofile': {\n"
"                'class': 'logging.FileHandler',\n"
"                'filename': 'mplog-foo.log',\n"
"                'mode': 'w',\n"
"                'formatter': 'detailed'\n"
"            },\n"
"            'errors': {\n"
"                'class': 'logging.FileHandler',\n"
"                'filename': 'mplog-errors.log',\n"
"                'mode': 'w',\n"
"                'formatter': 'detailed',\n"
"                'level': 'ERROR'\n"
"            }\n"
"        },\n"
"        'loggers': {\n"
"            'foo': {\n"
"                'handlers': ['foofile']\n"
"            }\n"
"        },\n"
"        'root': {\n"
"            'handlers': ['console', 'file', 'errors'],\n"
"            'level': 'DEBUG'\n"
"        }\n"
"    }\n"
"    # Log some initial events, just to show that logging in the parent "
"works\n"
"    # normally.\n"
"    logging.config.dictConfig(config_initial)\n"
"    logger = logging.getLogger('setup')\n"
"    logger.info('About to create workers ...')\n"
"    workers = []\n"
"    for i in range(5):\n"
"        wp = Process(target=worker_process, name='worker %d' % (i + 1),\n"
"                     args=(config_worker,))\n"
"        workers.append(wp)\n"
"        wp.start()\n"
"        logger.info('Started worker: %s', wp.name)\n"
"    logger.info('About to create listener ...')\n"
"    stop_event = Event()\n"
"    lp = Process(target=listener_process, name='listener',\n"
"                 args=(q, stop_event, config_listener))\n"
"    lp.start()\n"
"    logger.info('Started listener')\n"
"    # We now hang around for the workers to finish their work.\n"
"    for wp in workers:\n"
"        wp.join()\n"
"    # Workers all done, listening can now stop.\n"
"    # Logging in the parent still works normally.\n"
"    logger.info('Telling listener to stop ...')\n"
"    stop_event.set()\n"
"    lp.join()\n"
"    logger.info('All done.')\n"
"\n"
"if __name__ == '__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:2435
msgid "Inserting a BOM into messages sent to a SysLogHandler"
msgstr ""

#: howto/logging-cookbook.rst:2437
msgid ""
":rfc:`5424` requires that a Unicode message be sent to a syslog daemon as a "
"set of bytes which have the following structure: an optional pure-ASCII "
"component, followed by a UTF-8 Byte Order Mark (BOM), followed by Unicode "
"encoded using UTF-8. (See the :rfc:`relevant section of the specification "
"<5424#section-6>`.)"
msgstr ""

#: howto/logging-cookbook.rst:2443
msgid ""
"In Python 3.1, code was added to :class:`~logging.handlers.SysLogHandler` to "
"insert a BOM into the message, but unfortunately, it was implemented "
"incorrectly, with the BOM appearing at the beginning of the message and "
"hence not allowing any pure-ASCII component to appear before it."
msgstr ""

#: howto/logging-cookbook.rst:2449
msgid ""
"As this behaviour is broken, the incorrect BOM insertion code is being "
"removed from Python 3.2.4 and later. However, it is not being replaced, and "
"if you want to produce :rfc:`5424`-compliant messages which include a BOM, "
"an optional pure-ASCII sequence before it and arbitrary Unicode after it, "
"encoded using UTF-8, then you need to do the following:"
msgstr ""

#: howto/logging-cookbook.rst:2455
msgid ""
"Attach a :class:`~logging.Formatter` instance to your :class:`~logging."
"handlers.SysLogHandler` instance, with a format string such as::"
msgstr ""

#: howto/logging-cookbook.rst:2459
msgid "'ASCII section\\ufeffUnicode section'"
msgstr ""

#: howto/logging-cookbook.rst:2461
msgid ""
"The Unicode code point U+FEFF, when encoded using UTF-8, will be encoded as "
"a UTF-8 BOM -- the byte-string ``b'\\xef\\xbb\\xbf'``."
msgstr ""

#: howto/logging-cookbook.rst:2464
msgid ""
"Replace the ASCII section with whatever placeholders you like, but make sure "
"that the data that appears in there after substitution is always ASCII (that "
"way, it will remain unchanged after UTF-8 encoding)."
msgstr ""

#: howto/logging-cookbook.rst:2468
msgid ""
"Replace the Unicode section with whatever placeholders you like; if the data "
"which appears there after substitution contains characters outside the ASCII "
"range, that's fine -- it will be encoded using UTF-8."
msgstr ""

#: howto/logging-cookbook.rst:2472
msgid ""
"The formatted message *will* be encoded using UTF-8 encoding by "
"``SysLogHandler``. If you follow the above rules, you should be able to "
"produce :rfc:`5424`-compliant messages. If you don't, logging may not "
"complain, but your messages will not be RFC 5424-compliant, and your syslog "
"daemon may complain."
msgstr ""

#: howto/logging-cookbook.rst:2479
msgid "Implementing structured logging"
msgstr ""

#: howto/logging-cookbook.rst:2481
msgid ""
"Although most logging messages are intended for reading by humans, and thus "
"not readily machine-parseable, there might be circumstances where you want "
"to output messages in a structured format which *is* capable of being parsed "
"by a program (without needing complex regular expressions to parse the log "
"message). This is straightforward to achieve using the logging package. "
"There are a number of ways in which this could be achieved, but the "
"following is a simple approach which uses JSON to serialise the event in a "
"machine-parseable manner::"
msgstr ""

#: howto/logging-cookbook.rst:2489
msgid ""
"import json\n"
"import logging\n"
"\n"
"class StructuredMessage:\n"
"    def __init__(self, message, /, **kwargs):\n"
"        self.message = message\n"
"        self.kwargs = kwargs\n"
"\n"
"    def __str__(self):\n"
"        return '%s >>> %s' % (self.message, json.dumps(self.kwargs))\n"
"\n"
"_ = StructuredMessage   # optional, to improve readability\n"
"\n"
"logging.basicConfig(level=logging.INFO, format='%(message)s')\n"
"logging.info(_('message 1', foo='bar', bar='baz', num=123, fnum=123.456))"
msgstr ""

#: howto/logging-cookbook.rst:2505
msgid "If the above script is run, it prints:"
msgstr ""

#: howto/logging-cookbook.rst:2507
msgid ""
"message 1 >>> {\"fnum\": 123.456, \"num\": 123, \"bar\": \"baz\", \"foo\": "
"\"bar\"}"
msgstr ""

#: howto/logging-cookbook.rst:2511 howto/logging-cookbook.rst:2553
msgid ""
"Note that the order of items might be different according to the version of "
"Python used."
msgstr ""

#: howto/logging-cookbook.rst:2514
msgid ""
"If you need more specialised processing, you can use a custom JSON encoder, "
"as in the following complete example::"
msgstr ""

#: howto/logging-cookbook.rst:2517
msgid ""
"import json\n"
"import logging\n"
"\n"
"\n"
"class Encoder(json.JSONEncoder):\n"
"    def default(self, o):\n"
"        if isinstance(o, set):\n"
"            return tuple(o)\n"
"        elif isinstance(o, str):\n"
"            return o.encode('unicode_escape').decode('ascii')\n"
"        return super().default(o)\n"
"\n"
"class StructuredMessage:\n"
"    def __init__(self, message, /, **kwargs):\n"
"        self.message = message\n"
"        self.kwargs = kwargs\n"
"\n"
"    def __str__(self):\n"
"        s = Encoder().encode(self.kwargs)\n"
"        return '%s >>> %s' % (self.message, s)\n"
"\n"
"_ = StructuredMessage   # optional, to improve readability\n"
"\n"
"def main():\n"
"    logging.basicConfig(level=logging.INFO, format='%(message)s')\n"
"    logging.info(_('message 1', set_value={1, 2, 3}, snowman='\\u2603'))\n"
"\n"
"if __name__ == '__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:2547
msgid "When the above script is run, it prints:"
msgstr ""

#: howto/logging-cookbook.rst:2549
msgid "message 1 >>> {\"snowman\": \"\\u2603\", \"set_value\": [1, 2, 3]}"
msgstr ""

#: howto/logging-cookbook.rst:2562
msgid "Customizing handlers with :func:`dictConfig`"
msgstr ""

#: howto/logging-cookbook.rst:2564
msgid ""
"There are times when you want to customize logging handlers in particular "
"ways, and if you use :func:`dictConfig` you may be able to do this without "
"subclassing. As an example, consider that you may want to set the ownership "
"of a log file. On POSIX, this is easily done using :func:`shutil.chown`, but "
"the file handlers in the stdlib don't offer built-in support. You can "
"customize handler creation using a plain function such as::"
msgstr ""

#: howto/logging-cookbook.rst:2571
msgid ""
"def owned_file_handler(filename, mode='a', encoding=None, owner=None):\n"
"    if owner:\n"
"        if not os.path.exists(filename):\n"
"            open(filename, 'a').close()\n"
"        shutil.chown(filename, *owner)\n"
"    return logging.FileHandler(filename, mode, encoding)"
msgstr ""

#: howto/logging-cookbook.rst:2578
msgid ""
"You can then specify, in a logging configuration passed to :func:"
"`dictConfig`, that a logging handler be created by calling this function::"
msgstr ""

#: howto/logging-cookbook.rst:2581
msgid ""
"LOGGING = {\n"
"    'version': 1,\n"
"    'disable_existing_loggers': False,\n"
"    'formatters': {\n"
"        'default': {\n"
"            'format': '%(asctime)s %(levelname)s %(name)s %(message)s'\n"
"        },\n"
"    },\n"
"    'handlers': {\n"
"        'file':{\n"
"            # The values below are popped from this dictionary and\n"
"            # used to create the handler, set the handler's level and\n"
"            # its formatter.\n"
"            '()': owned_file_handler,\n"
"            'level':'DEBUG',\n"
"            'formatter': 'default',\n"
"            # The values below are passed to the handler creator callable\n"
"            # as keyword arguments.\n"
"            'owner': ['pulse', 'pulse'],\n"
"            'filename': 'chowntest.log',\n"
"            'mode': 'w',\n"
"            'encoding': 'utf-8',\n"
"        },\n"
"    },\n"
"    'root': {\n"
"        'handlers': ['file'],\n"
"        'level': 'DEBUG',\n"
"    },\n"
"}"
msgstr ""

#: howto/logging-cookbook.rst:2611
msgid ""
"In this example I am setting the ownership using the ``pulse`` user and "
"group, just for the purposes of illustration. Putting it together into a "
"working script, ``chowntest.py``::"
msgstr ""

#: howto/logging-cookbook.rst:2615
msgid ""
"import logging, logging.config, os, shutil\n"
"\n"
"def owned_file_handler(filename, mode='a', encoding=None, owner=None):\n"
"    if owner:\n"
"        if not os.path.exists(filename):\n"
"            open(filename, 'a').close()\n"
"        shutil.chown(filename, *owner)\n"
"    return logging.FileHandler(filename, mode, encoding)\n"
"\n"
"LOGGING = {\n"
"    'version': 1,\n"
"    'disable_existing_loggers': False,\n"
"    'formatters': {\n"
"        'default': {\n"
"            'format': '%(asctime)s %(levelname)s %(name)s %(message)s'\n"
"        },\n"
"    },\n"
"    'handlers': {\n"
"        'file':{\n"
"            # The values below are popped from this dictionary and\n"
"            # used to create the handler, set the handler's level and\n"
"            # its formatter.\n"
"            '()': owned_file_handler,\n"
"            'level':'DEBUG',\n"
"            'formatter': 'default',\n"
"            # The values below are passed to the handler creator callable\n"
"            # as keyword arguments.\n"
"            'owner': ['pulse', 'pulse'],\n"
"            'filename': 'chowntest.log',\n"
"            'mode': 'w',\n"
"            'encoding': 'utf-8',\n"
"        },\n"
"    },\n"
"    'root': {\n"
"        'handlers': ['file'],\n"
"        'level': 'DEBUG',\n"
"    },\n"
"}\n"
"\n"
"logging.config.dictConfig(LOGGING)\n"
"logger = logging.getLogger('mylogger')\n"
"logger.debug('A debug message')"
msgstr ""

#: howto/logging-cookbook.rst:2658
msgid "To run this, you will probably need to run as ``root``:"
msgstr ""

#: howto/logging-cookbook.rst:2660
msgid ""
"$ sudo python3.3 chowntest.py\n"
"$ cat chowntest.log\n"
"2013-11-05 09:34:51,128 DEBUG mylogger A debug message\n"
"$ ls -l chowntest.log\n"
"-rw-r--r-- 1 pulse pulse 55 2013-11-05 09:34 chowntest.log"
msgstr ""

#: howto/logging-cookbook.rst:2668
msgid ""
"Note that this example uses Python 3.3 because that's where :func:`shutil."
"chown` makes an appearance. This approach should work with any Python "
"version that supports :func:`dictConfig` - namely, Python 2.7, 3.2 or later. "
"With pre-3.3 versions, you would need to implement the actual ownership "
"change using e.g. :func:`os.chown`."
msgstr ""

#: howto/logging-cookbook.rst:2674
msgid ""
"In practice, the handler-creating function may be in a utility module "
"somewhere in your project. Instead of the line in the configuration::"
msgstr ""

#: howto/logging-cookbook.rst:2677
msgid "'()': owned_file_handler,"
msgstr ""

#: howto/logging-cookbook.rst:2679
msgid "you could use e.g.::"
msgstr ""

#: howto/logging-cookbook.rst:2681
msgid "'()': 'ext://project.util.owned_file_handler',"
msgstr ""

#: howto/logging-cookbook.rst:2683
msgid ""
"where ``project.util`` can be replaced with the actual name of the package "
"where the function resides. In the above working script, using ``'ext://"
"__main__.owned_file_handler'`` should work. Here, the actual callable is "
"resolved by :func:`dictConfig` from the ``ext://`` specification."
msgstr ""

#: howto/logging-cookbook.rst:2688
msgid ""
"This example hopefully also points the way to how you could implement other "
"types of file change - e.g. setting specific POSIX permission bits - in the "
"same way, using :func:`os.chmod`."
msgstr ""

#: howto/logging-cookbook.rst:2692
msgid ""
"Of course, the approach could also be extended to types of handler other "
"than a :class:`~logging.FileHandler` - for example, one of the rotating file "
"handlers, or a different type of handler altogether."
msgstr ""

#: howto/logging-cookbook.rst:2702
msgid "Using particular formatting styles throughout your application"
msgstr ""

#: howto/logging-cookbook.rst:2704
msgid ""
"In Python 3.2, the :class:`~logging.Formatter` gained a ``style`` keyword "
"parameter which, while defaulting to ``%`` for backward compatibility, "
"allowed the specification of ``{`` or ``$`` to support the formatting "
"approaches supported by :meth:`str.format` and :class:`string.Template`. "
"Note that this governs the formatting of logging messages for final output "
"to logs, and is completely orthogonal to how an individual logging message "
"is constructed."
msgstr ""

#: howto/logging-cookbook.rst:2711
msgid ""
"Logging calls (:meth:`~Logger.debug`, :meth:`~Logger.info` etc.) only take "
"positional parameters for the actual logging message itself, with keyword "
"parameters used only for determining options for how to handle the logging "
"call (e.g. the ``exc_info`` keyword parameter to indicate that traceback "
"information should be logged, or the ``extra`` keyword parameter to indicate "
"additional contextual information to be added to the log). So you cannot "
"directly make logging calls using :meth:`str.format` or :class:`string."
"Template` syntax, because internally the logging package uses %-formatting "
"to merge the format string and the variable arguments. There would be no "
"changing this while preserving backward compatibility, since all logging "
"calls which are out there in existing code will be using %-format strings."
msgstr ""

#: howto/logging-cookbook.rst:2723
msgid ""
"There have been suggestions to associate format styles with specific "
"loggers, but that approach also runs into backward compatibility problems "
"because any existing code could be using a given logger name and using %-"
"formatting."
msgstr ""

#: howto/logging-cookbook.rst:2727
msgid ""
"For logging to work interoperably between any third-party libraries and your "
"code, decisions about formatting need to be made at the level of the "
"individual logging call. This opens up a couple of ways in which alternative "
"formatting styles can be accommodated."
msgstr ""

#: howto/logging-cookbook.rst:2734
msgid "Using LogRecord factories"
msgstr ""

#: howto/logging-cookbook.rst:2736
msgid ""
"In Python 3.2, along with the :class:`~logging.Formatter` changes mentioned "
"above, the logging package gained the ability to allow users to set their "
"own :class:`LogRecord` subclasses, using the :func:`setLogRecordFactory` "
"function. You can use this to set your own subclass of :class:`LogRecord`, "
"which does the Right Thing by overriding the :meth:`~LogRecord.getMessage` "
"method. The base class implementation of this method is where the ``msg % "
"args`` formatting happens, and where you can substitute your alternate "
"formatting; however, you should be careful to support all formatting styles "
"and allow %-formatting as the default, to ensure interoperability with other "
"code. Care should also be taken to call ``str(self.msg)``, just as the base "
"implementation does."
msgstr ""

#: howto/logging-cookbook.rst:2747
msgid ""
"Refer to the reference documentation on :func:`setLogRecordFactory` and :"
"class:`LogRecord` for more information."
msgstr ""

#: howto/logging-cookbook.rst:2752
msgid "Using custom message objects"
msgstr ""

#: howto/logging-cookbook.rst:2754
msgid ""
"There is another, perhaps simpler way that you can use {}- and $- formatting "
"to construct your individual log messages. You may recall (from :ref:"
"`arbitrary-object-messages`) that when logging you can use an arbitrary "
"object as a message format string, and that the logging package will call :"
"func:`str` on that object to get the actual format string. Consider the "
"following two classes::"
msgstr ""

#: howto/logging-cookbook.rst:2779
msgid ""
"Either of these can be used in place of a format string, to allow {}- or $-"
"formatting to be used to build the actual \"message\" part which appears in "
"the formatted log output in place of &ldquo;%(message)s&rdquo; or &ldquo;{message}&rdquo; or "
"&ldquo;$message&rdquo;. If you find it a little unwieldy to use the class names whenever "
"you want to log something, you can make it more palatable if you use an "
"alias such as ``M`` or ``_`` for the message (or perhaps ``__``, if you are "
"using ``_`` for localization)."
msgstr ""

#: howto/logging-cookbook.rst:2787
msgid ""
"Examples of this approach are given below. Firstly, formatting with :meth:"
"`str.format`::"
msgstr ""

#: howto/logging-cookbook.rst:2790
msgid ""
">>> __ = BraceMessage\n"
">>> print(__('Message with {0} {1}', 2, 'placeholders'))\n"
"Message with 2 placeholders\n"
">>> class Point: pass\n"
"...\n"
">>> p = Point()\n"
">>> p.x = 0.5\n"
">>> p.y = 0.5\n"
">>> print(__('Message with coordinates: ({point.x:.2f}, {point.y:.2f})', "
"point=p))\n"
"Message with coordinates: (0.50, 0.50)"
msgstr ""

#: howto/logging-cookbook.rst:2801
msgid "Secondly, formatting with :class:`string.Template`::"
msgstr ""

#: howto/logging-cookbook.rst:2803
msgid ""
">>> __ = DollarMessage\n"
">>> print(__('Message with $num $what', num=2, what='placeholders'))\n"
"Message with 2 placeholders\n"
">>>"
msgstr ""

#: howto/logging-cookbook.rst:2808
msgid ""
"One thing to note is that you pay no significant performance penalty with "
"this approach: the actual formatting happens not when you make the logging "
"call, but when (and if) the logged message is actually about to be output to "
"a log by a handler. So the only slightly unusual thing which might trip you "
"up is that the parentheses go around the format string and the arguments, "
"not just the format string. That&rsquo;s because the __ notation is just syntax "
"sugar for a constructor call to one of the :samp:`{XXX}Message` classes "
"shown above."
msgstr ""

#: howto/logging-cookbook.rst:2822
msgid "Configuring filters with :func:`dictConfig`"
msgstr ""

#: howto/logging-cookbook.rst:2824
msgid ""
"You *can* configure filters using :func:`~logging.config.dictConfig`, though "
"it might not be obvious at first glance how to do it (hence this recipe). "
"Since :class:`~logging.Filter` is the only filter class included in the "
"standard library, and it is unlikely to cater to many requirements (it's "
"only there as a base class), you will typically need to define your own :"
"class:`~logging.Filter` subclass with an overridden :meth:`~logging.Filter."
"filter` method. To do this, specify the ``()`` key in the configuration "
"dictionary for the filter, specifying a callable which will be used to "
"create the filter (a class is the most obvious, but you can provide any "
"callable which returns a :class:`~logging.Filter` instance). Here is a "
"complete example::"
msgstr ""

#: howto/logging-cookbook.rst:2835
msgid ""
"import logging\n"
"import logging.config\n"
"import sys\n"
"\n"
"class MyFilter(logging.Filter):\n"
"    def __init__(self, param=None):\n"
"        self.param = param\n"
"\n"
"    def filter(self, record):\n"
"        if self.param is None:\n"
"            allow = True\n"
"        else:\n"
"            allow = self.param not in record.msg\n"
"        if allow:\n"
"            record.msg = 'changed: ' + record.msg\n"
"        return allow\n"
"\n"
"LOGGING = {\n"
"    'version': 1,\n"
"    'filters': {\n"
"        'myfilter': {\n"
"            '()': MyFilter,\n"
"            'param': 'noshow',\n"
"        }\n"
"    },\n"
"    'handlers': {\n"
"        'console': {\n"
"            'class': 'logging.StreamHandler',\n"
"            'filters': ['myfilter']\n"
"        }\n"
"    },\n"
"    'root': {\n"
"        'level': 'DEBUG',\n"
"        'handlers': ['console']\n"
"    },\n"
"}\n"
"\n"
"if __name__ == '__main__':\n"
"    logging.config.dictConfig(LOGGING)\n"
"    logging.debug('hello')\n"
"    logging.debug('hello - noshow')"
msgstr ""

#: howto/logging-cookbook.rst:2877
msgid ""
"This example shows how you can pass configuration data to the callable which "
"constructs the instance, in the form of keyword parameters. When run, the "
"above script will print:"
msgstr ""

#: howto/logging-cookbook.rst:2881
msgid "changed: hello"
msgstr ""

#: howto/logging-cookbook.rst:2885
msgid "which shows that the filter is working as configured."
msgstr ""

#: howto/logging-cookbook.rst:2887
msgid "A couple of extra points to note:"
msgstr ""

#: howto/logging-cookbook.rst:2889
msgid ""
"If you can't refer to the callable directly in the configuration (e.g. if it "
"lives in a different module, and you can't import it directly where the "
"configuration dictionary is), you can use the form ``ext://...`` as "
"described in :ref:`logging-config-dict-externalobj`. For example, you could "
"have used the text ``'ext://__main__.MyFilter'`` instead of ``MyFilter`` in "
"the above example."
msgstr ""

#: howto/logging-cookbook.rst:2896
msgid ""
"As well as for filters, this technique can also be used to configure custom "
"handlers and formatters. See :ref:`logging-config-dict-userdef` for more "
"information on how logging supports using user-defined objects in its "
"configuration, and see the other cookbook recipe :ref:`custom-handlers` "
"above."
msgstr ""

#: howto/logging-cookbook.rst:2905
msgid "Customized exception formatting"
msgstr ""

#: howto/logging-cookbook.rst:2907
msgid ""
"There might be times when you want to do customized exception formatting - "
"for argument's sake, let's say you want exactly one line per logged event, "
"even when exception information is present. You can do this with a custom "
"formatter class, as shown in the following example::"
msgstr ""

#: howto/logging-cookbook.rst:2912
msgid ""
"import logging\n"
"\n"
"class OneLineExceptionFormatter(logging.Formatter):\n"
"    def formatException(self, exc_info):\n"
"        \"\"\"\n"
"        Format an exception so that it prints on a single line.\n"
"        \"\"\"\n"
"        result = super().formatException(exc_info)\n"
"        return repr(result)  # or format into one line however you want to\n"
"\n"
"    def format(self, record):\n"
"        s = super().format(record)\n"
"        if record.exc_text:\n"
"            s = s.replace('\\n', '') + '|'\n"
"        return s\n"
"\n"
"def configure_logging():\n"
"    fh = logging.FileHandler('output.txt', 'w')\n"
"    f = OneLineExceptionFormatter('%(asctime)s|%(levelname)s|%(message)s|',\n"
"                                  '%d/%m/%Y %H:%M:%S')\n"
"    fh.setFormatter(f)\n"
"    root = logging.getLogger()\n"
"    root.setLevel(logging.DEBUG)\n"
"    root.addHandler(fh)\n"
"\n"
"def main():\n"
"    configure_logging()\n"
"    logging.info('Sample message')\n"
"    try:\n"
"        x = 1 / 0\n"
"    except ZeroDivisionError as e:\n"
"        logging.exception('ZeroDivisionError: %s', e)\n"
"\n"
"if __name__ == '__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:2948
msgid "When run, this produces a file with exactly two lines:"
msgstr ""

#: howto/logging-cookbook.rst:2950
msgid ""
"28/01/2015 07:21:23|INFO|Sample message|\n"
"28/01/2015 07:21:23|ERROR|ZeroDivisionError: integer division or modulo by "
"zero|'Traceback (most recent call last):\\n  File \"logtest7.py\", line 30, "
"in main\\n    x = 1 / 0\\nZeroDivisionError: integer division or modulo by "
"zero'|"
msgstr ""

#: howto/logging-cookbook.rst:2955
msgid ""
"While the above treatment is simplistic, it points the way to how exception "
"information can be formatted to your liking. The :mod:`traceback` module may "
"be helpful for more specialized needs."
msgstr ""

#: howto/logging-cookbook.rst:2962
msgid "Speaking logging messages"
msgstr ""

#: howto/logging-cookbook.rst:2964
msgid ""
"There might be situations when it is desirable to have logging messages "
"rendered in an audible rather than a visible format. This is easy to do if "
"you have text-to-speech (TTS) functionality available in your system, even "
"if it doesn't have a Python binding. Most TTS systems have a command line "
"program you can run, and this can be invoked from a handler using :mod:"
"`subprocess`. It's assumed here that TTS command line programs won't expect "
"to interact with users or take a long time to complete, and that the "
"frequency of logged messages will be not so high as to swamp the user with "
"messages, and that it's acceptable to have the messages spoken one at a time "
"rather than concurrently, The example implementation below waits for one "
"message to be spoken before the next is processed, and this might cause "
"other handlers to be kept waiting. Here is a short example showing the "
"approach, which assumes that the ``espeak`` TTS package is available::"
msgstr ""

#: howto/logging-cookbook.rst:2977
msgid ""
"import logging\n"
"import subprocess\n"
"import sys\n"
"\n"
"class TTSHandler(logging.Handler):\n"
"    def emit(self, record):\n"
"        msg = self.format(record)\n"
"        # Speak slowly in a female English voice\n"
"        cmd = ['espeak', '-s150', '-ven+f3', msg]\n"
"        p = subprocess.Popen(cmd, stdout=subprocess.PIPE,\n"
"                             stderr=subprocess.STDOUT)\n"
"        # wait for the program to finish\n"
"        p.communicate()\n"
"\n"
"def configure_logging():\n"
"    h = TTSHandler()\n"
"    root = logging.getLogger()\n"
"    root.addHandler(h)\n"
"    # the default formatter just returns the message\n"
"    root.setLevel(logging.DEBUG)\n"
"\n"
"def main():\n"
"    logging.info('Hello')\n"
"    logging.debug('Goodbye')\n"
"\n"
"if __name__ == '__main__':\n"
"    configure_logging()\n"
"    sys.exit(main())"
msgstr ""

#: howto/logging-cookbook.rst:3006
msgid ""
"When run, this script should say \"Hello\" and then \"Goodbye\" in a female "
"voice."
msgstr ""

#: howto/logging-cookbook.rst:3008
msgid ""
"The above approach can, of course, be adapted to other TTS systems and even "
"other systems altogether which can process messages via external programs "
"run from a command line."
msgstr ""

#: howto/logging-cookbook.rst:3016
msgid "Buffering logging messages and outputting them conditionally"
msgstr ""

#: howto/logging-cookbook.rst:3018
msgid ""
"There might be situations where you want to log messages in a temporary area "
"and only output them if a certain condition occurs. For example, you may "
"want to start logging debug events in a function, and if the function "
"completes without errors, you don't want to clutter the log with the "
"collected debug information, but if there is an error, you want all the "
"debug information to be output as well as the error."
msgstr ""

#: howto/logging-cookbook.rst:3025
msgid ""
"Here is an example which shows how you could do this using a decorator for "
"your functions where you want logging to behave this way. It makes use of "
"the :class:`logging.handlers.MemoryHandler`, which allows buffering of "
"logged events until some condition occurs, at which point the buffered "
"events are ``flushed`` - passed to another handler (the ``target`` handler) "
"for processing. By default, the ``MemoryHandler`` flushed when its buffer "
"gets filled up or an event whose level is greater than or equal to a "
"specified threshold is seen. You can use this recipe with a more specialised "
"subclass of ``MemoryHandler`` if you want custom flushing behavior."
msgstr ""

#: howto/logging-cookbook.rst:3035
msgid ""
"The example script has a simple function, ``foo``, which just cycles through "
"all the logging levels, writing to ``sys.stderr`` to say what level it's "
"about to log at, and then actually logging a message at that level. You can "
"pass a parameter to ``foo`` which, if true, will log at ERROR and CRITICAL "
"levels - otherwise, it only logs at DEBUG, INFO and WARNING levels."
msgstr ""

#: howto/logging-cookbook.rst:3041
msgid ""
"The script just arranges to decorate ``foo`` with a decorator which will do "
"the conditional logging that's required. The decorator takes a logger as a "
"parameter and attaches a memory handler for the duration of the call to the "
"decorated function. The decorator can be additionally parameterised using a "
"target handler, a level at which flushing should occur, and a capacity for "
"the buffer (number of records buffered). These default to a :class:`~logging."
"StreamHandler` which writes to ``sys.stderr``, ``logging.ERROR`` and ``100`` "
"respectively."
msgstr ""

#: howto/logging-cookbook.rst:3049
msgid "Here's the script::"
msgstr ""

#: howto/logging-cookbook.rst:3051
msgid ""
"import logging\n"
"from logging.handlers import MemoryHandler\n"
"import sys\n"
"\n"
"logger = logging.getLogger(__name__)\n"
"logger.addHandler(logging.NullHandler())\n"
"\n"
"def log_if_errors(logger, target_handler=None, flush_level=None, "
"capacity=None):\n"
"    if target_handler is None:\n"
"        target_handler = logging.StreamHandler()\n"
"    if flush_level is None:\n"
"        flush_level = logging.ERROR\n"
"    if capacity is None:\n"
"        capacity = 100\n"
"    handler = MemoryHandler(capacity, flushLevel=flush_level, "
"target=target_handler)\n"
"\n"
"    def decorator(fn):\n"
"        def wrapper(*args, **kwargs):\n"
"            logger.addHandler(handler)\n"
"            try:\n"
"                return fn(*args, **kwargs)\n"
"            except Exception:\n"
"                logger.exception('call failed')\n"
"                raise\n"
"            finally:\n"
"                super(MemoryHandler, handler).flush()\n"
"                logger.removeHandler(handler)\n"
"        return wrapper\n"
"\n"
"    return decorator\n"
"\n"
"def write_line(s):\n"
"    sys.stderr.write('%s\\n' % s)\n"
"\n"
"def foo(fail=False):\n"
"    write_line('about to log at DEBUG ...')\n"
"    logger.debug('Actually logged at DEBUG')\n"
"    write_line('about to log at INFO ...')\n"
"    logger.info('Actually logged at INFO')\n"
"    write_line('about to log at WARNING ...')\n"
"    logger.warning('Actually logged at WARNING')\n"
"    if fail:\n"
"        write_line('about to log at ERROR ...')\n"
"        logger.error('Actually logged at ERROR')\n"
"        write_line('about to log at CRITICAL ...')\n"
"        logger.critical('Actually logged at CRITICAL')\n"
"    return fail\n"
"\n"
"decorated_foo = log_if_errors(logger)(foo)\n"
"\n"
"if __name__ == '__main__':\n"
"    logger.setLevel(logging.DEBUG)\n"
"    write_line('Calling undecorated foo with False')\n"
"    assert not foo(False)\n"
"    write_line('Calling undecorated foo with True')\n"
"    assert foo(True)\n"
"    write_line('Calling decorated foo with False')\n"
"    assert not decorated_foo(False)\n"
"    write_line('Calling decorated foo with True')\n"
"    assert decorated_foo(True)"
msgstr ""

#: howto/logging-cookbook.rst:3112
msgid "When this script is run, the following output should be observed:"
msgstr ""

#: howto/logging-cookbook.rst:3114
msgid ""
"Calling undecorated foo with False\n"
"about to log at DEBUG ...\n"
"about to log at INFO ...\n"
"about to log at WARNING ...\n"
"Calling undecorated foo with True\n"
"about to log at DEBUG ...\n"
"about to log at INFO ...\n"
"about to log at WARNING ...\n"
"about to log at ERROR ...\n"
"about to log at CRITICAL ...\n"
"Calling decorated foo with False\n"
"about to log at DEBUG ...\n"
"about to log at INFO ...\n"
"about to log at WARNING ...\n"
"Calling decorated foo with True\n"
"about to log at DEBUG ...\n"
"about to log at INFO ...\n"
"about to log at WARNING ...\n"
"about to log at ERROR ...\n"
"Actually logged at DEBUG\n"
"Actually logged at INFO\n"
"Actually logged at WARNING\n"
"Actually logged at ERROR\n"
"about to log at CRITICAL ...\n"
"Actually logged at CRITICAL"
msgstr ""

#: howto/logging-cookbook.rst:3142
msgid ""
"As you can see, actual logging output only occurs when an event is logged "
"whose severity is ERROR or greater, but in that case, any previous events at "
"lower severities are also logged."
msgstr ""

#: howto/logging-cookbook.rst:3146
msgid "You can of course use the conventional means of decoration::"
msgstr ""

#: howto/logging-cookbook.rst:3148
msgid ""
"@log_if_errors(logger)\n"
"def foo(fail=False):\n"
"    ..."
msgstr ""

#: howto/logging-cookbook.rst:3156
msgid "Sending logging messages to email, with buffering"
msgstr ""

#: howto/logging-cookbook.rst:3158
msgid ""
"To illustrate how you can send log messages via email, so that a set number "
"of messages are sent per email, you can subclass :class:`~logging.handlers."
"BufferingHandler`. In the following  example, which you can adapt to suit "
"your specific needs, a simple test harness is provided which allows you to "
"run the script with command line arguments specifying what you typically "
"need to send things via SMTP. (Run the downloaded script with the ``-h`` "
"argument to see the required and optional arguments.)"
msgstr ""

#: howto/logging-cookbook.rst:3166
msgid ""
"import logging\n"
"import logging.handlers\n"
"import smtplib\n"
"\n"
"class BufferingSMTPHandler(logging.handlers.BufferingHandler):\n"
"    def __init__(self, mailhost, port, username, password, fromaddr, "
"toaddrs,\n"
"                 subject, capacity):\n"
"        logging.handlers.BufferingHandler.__init__(self, capacity)\n"
"        self.mailhost = mailhost\n"
"        self.mailport = port\n"
"        self.username = username\n"
"        self.password = password\n"
"        self.fromaddr = fromaddr\n"
"        if isinstance(toaddrs, str):\n"
"            toaddrs = [toaddrs]\n"
"        self.toaddrs = toaddrs\n"
"        self.subject = subject\n"
"        self.setFormatter(logging.Formatter(\"%(asctime)s %(levelname)-5s "
"%(message)s\"))\n"
"\n"
"    def flush(self):\n"
"        if len(self.buffer) > 0:\n"
"            try:\n"
"                smtp = smtplib.SMTP(self.mailhost, self.mailport)\n"
"                smtp.starttls()\n"
"                smtp.login(self.username, self.password)\n"
"                msg = \"From: %s\\r\\nTo: %s\\r\\nSubject: %s\\r\\n\\r\\n\" "
"% (self.fromaddr, ','.join(self.toaddrs), self.subject)\n"
"                for record in self.buffer:\n"
"                    s = self.format(record)\n"
"                    msg = msg + s + \"\\r\\n\"\n"
"                smtp.sendmail(self.fromaddr, self.toaddrs, msg)\n"
"                smtp.quit()\n"
"            except Exception:\n"
"                if logging.raiseExceptions:\n"
"                    raise\n"
"            self.buffer = []\n"
"\n"
"if __name__ == '__main__':\n"
"    import argparse\n"
"\n"
"    ap = argparse.ArgumentParser()\n"
"    aa = ap.add_argument\n"
"    aa('host', metavar='HOST', help='SMTP server')\n"
"    aa('--port', '-p', type=int, default=587, help='SMTP port')\n"
"    aa('user', metavar='USER', help='SMTP username')\n"
"    aa('password', metavar='PASSWORD', help='SMTP password')\n"
"    aa('to', metavar='TO', help='Addressee for emails')\n"
"    aa('sender', metavar='SENDER', help='Sender email address')\n"
"    aa('--subject', '-s',\n"
"       default='Test Logging email from Python logging module (buffering)',\n"
"       help='Subject of email')\n"
"    options = ap.parse_args()\n"
"    logger = logging.getLogger()\n"
"    logger.setLevel(logging.DEBUG)\n"
"    h = BufferingSMTPHandler(options.host, options.port, options.user,\n"
"                             options.password, options.sender,\n"
"                             options.to, options.subject, 10)\n"
"    logger.addHandler(h)\n"
"    for i in range(102):\n"
"        logger.info(\"Info index = %d\", i)\n"
"    h.flush()\n"
"    h.close()"
msgstr ""

#: howto/logging-cookbook.rst:3230
msgid ""
"If you run this script and your SMTP server is correctly set up, you should "
"find that it sends eleven emails to the addressee you specify. The first ten "
"emails will each have ten log messages, and the eleventh will have two "
"messages. That makes up 102 messages as specified in the script."
msgstr ""

#: howto/logging-cookbook.rst:3238
msgid "Formatting times using UTC (GMT) via configuration"
msgstr ""

#: howto/logging-cookbook.rst:3240
msgid ""
"Sometimes you want to format times using UTC, which can be done using a "
"class such as ``UTCFormatter``, shown below::"
msgstr ""

#: howto/logging-cookbook.rst:3243
msgid ""
"import logging\n"
"import time\n"
"\n"
"class UTCFormatter(logging.Formatter):\n"
"    converter = time.gmtime"
msgstr ""

#: howto/logging-cookbook.rst:3249
msgid ""
"and you can then use the ``UTCFormatter`` in your code instead of :class:"
"`~logging.Formatter`. If you want to do that via configuration, you can use "
"the :func:`~logging.config.dictConfig` API with an approach illustrated by "
"the following complete example::"
msgstr ""

#: howto/logging-cookbook.rst:3254
msgid ""
"import logging\n"
"import logging.config\n"
"import time\n"
"\n"
"class UTCFormatter(logging.Formatter):\n"
"    converter = time.gmtime\n"
"\n"
"LOGGING = {\n"
"    'version': 1,\n"
"    'disable_existing_loggers': False,\n"
"    'formatters': {\n"
"        'utc': {\n"
"            '()': UTCFormatter,\n"
"            'format': '%(asctime)s %(message)s',\n"
"        },\n"
"        'local': {\n"
"            'format': '%(asctime)s %(message)s',\n"
"        }\n"
"    },\n"
"    'handlers': {\n"
"        'console1': {\n"
"            'class': 'logging.StreamHandler',\n"
"            'formatter': 'utc',\n"
"        },\n"
"        'console2': {\n"
"            'class': 'logging.StreamHandler',\n"
"            'formatter': 'local',\n"
"        },\n"
"    },\n"
"    'root': {\n"
"        'handlers': ['console1', 'console2'],\n"
"   }\n"
"}\n"
"\n"
"if __name__ == '__main__':\n"
"    logging.config.dictConfig(LOGGING)\n"
"    logging.warning('The local time is %s', time.asctime())"
msgstr ""

#: howto/logging-cookbook.rst:3292
msgid "When this script is run, it should print something like:"
msgstr ""

#: howto/logging-cookbook.rst:3294
msgid ""
"2015-10-17 12:53:29,501 The local time is Sat Oct 17 13:53:29 2015\n"
"2015-10-17 13:53:29,501 The local time is Sat Oct 17 13:53:29 2015"
msgstr ""

#: howto/logging-cookbook.rst:3299
msgid ""
"showing how the time is formatted both as local time and UTC, one for each "
"handler."
msgstr ""

#: howto/logging-cookbook.rst:3306
msgid "Using a context manager for selective logging"
msgstr ""

#: howto/logging-cookbook.rst:3308
msgid ""
"There are times when it would be useful to temporarily change the logging "
"configuration and revert it back after doing something. For this, a context "
"manager is the most obvious way of saving and restoring the logging context. "
"Here is a simple example of such a context manager, which allows you to "
"optionally change the logging level and add a logging handler purely in the "
"scope of the context manager::"
msgstr ""

#: howto/logging-cookbook.rst:3315
msgid ""
"import logging\n"
"import sys\n"
"\n"
"class LoggingContext:\n"
"    def __init__(self, logger, level=None, handler=None, close=True):\n"
"        self.logger = logger\n"
"        self.level = level\n"
"        self.handler = handler\n"
"        self.close = close\n"
"\n"
"    def __enter__(self):\n"
"        if self.level is not None:\n"
"            self.old_level = self.logger.level\n"
"            self.logger.setLevel(self.level)\n"
"        if self.handler:\n"
"            self.logger.addHandler(self.handler)\n"
"\n"
"    def __exit__(self, et, ev, tb):\n"
"        if self.level is not None:\n"
"            self.logger.setLevel(self.old_level)\n"
"        if self.handler:\n"
"            self.logger.removeHandler(self.handler)\n"
"        if self.handler and self.close:\n"
"            self.handler.close()\n"
"        # implicit return of None => don't swallow exceptions"
msgstr ""

#: howto/logging-cookbook.rst:3341
msgid ""
"If you specify a level value, the logger's level is set to that value in the "
"scope of the with block covered by the context manager. If you specify a "
"handler, it is added to the logger on entry to the block and removed on exit "
"from the block. You can also ask the manager to close the handler for you on "
"block exit - you could do this if you don't need the handler any more."
msgstr ""

#: howto/logging-cookbook.rst:3347
msgid ""
"To illustrate how it works, we can add the following block of code to the "
"above::"
msgstr ""

#: howto/logging-cookbook.rst:3350
msgid ""
"if __name__ == '__main__':\n"
"    logger = logging.getLogger('foo')\n"
"    logger.addHandler(logging.StreamHandler())\n"
"    logger.setLevel(logging.INFO)\n"
"    logger.info('1. This should appear just once on stderr.')\n"
"    logger.debug('2. This should not appear.')\n"
"    with LoggingContext(logger, level=logging.DEBUG):\n"
"        logger.debug('3. This should appear once on stderr.')\n"
"    logger.debug('4. This should not appear.')\n"
"    h = logging.StreamHandler(sys.stdout)\n"
"    with LoggingContext(logger, level=logging.DEBUG, handler=h, "
"close=True):\n"
"        logger.debug('5. This should appear twice - once on stderr and once "
"on stdout.')\n"
"    logger.info('6. This should appear just once on stderr.')\n"
"    logger.debug('7. This should not appear.')"
msgstr ""

#: howto/logging-cookbook.rst:3365
msgid ""
"We initially set the logger's level to ``INFO``, so message #1 appears and "
"message #2 doesn't. We then change the level to ``DEBUG`` temporarily in the "
"following ``with`` block, and so message #3 appears. After the block exits, "
"the logger's level is restored to ``INFO`` and so message #4 doesn't appear. "
"In the next ``with`` block, we set the level to ``DEBUG`` again but also add "
"a handler writing to ``sys.stdout``. Thus, message #5 appears twice on the "
"console (once via ``stderr`` and once via ``stdout``). After the ``with`` "
"statement's completion, the status is as it was before so message #6 appears "
"(like message #1) whereas message #7 doesn't (just like message #2)."
msgstr ""

#: howto/logging-cookbook.rst:3375
msgid "If we run the resulting script, the result is as follows:"
msgstr ""

#: howto/logging-cookbook.rst:3377
msgid ""
"$ python logctx.py\n"
"1. This should appear just once on stderr.\n"
"3. This should appear once on stderr.\n"
"5. This should appear twice - once on stderr and once on stdout.\n"
"5. This should appear twice - once on stderr and once on stdout.\n"
"6. This should appear just once on stderr."
msgstr ""

#: howto/logging-cookbook.rst:3386
msgid ""
"If we run it again, but pipe ``stderr`` to ``/dev/null``, we see the "
"following, which is the only message written to ``stdout``:"
msgstr ""

#: howto/logging-cookbook.rst:3389
msgid ""
"$ python logctx.py 2>/dev/null\n"
"5. This should appear twice - once on stderr and once on stdout."
msgstr ""

#: howto/logging-cookbook.rst:3394
msgid "Once again, but piping ``stdout`` to ``/dev/null``, we get:"
msgstr ""

#: howto/logging-cookbook.rst:3396
msgid ""
"$ python logctx.py >/dev/null\n"
"1. This should appear just once on stderr.\n"
"3. This should appear once on stderr.\n"
"5. This should appear twice - once on stderr and once on stdout.\n"
"6. This should appear just once on stderr."
msgstr ""

#: howto/logging-cookbook.rst:3404
msgid ""
"In this case, the message #5 printed to ``stdout`` doesn't appear, as "
"expected."
msgstr ""

#: howto/logging-cookbook.rst:3406
msgid ""
"Of course, the approach described here can be generalised, for example to "
"attach logging filters temporarily. Note that the above code works in Python "
"2 as well as Python 3."
msgstr ""

#: howto/logging-cookbook.rst:3414
msgid "A CLI application starter template"
msgstr ""

#: howto/logging-cookbook.rst:3416
msgid "Here's an example which shows how you can:"
msgstr ""

#: howto/logging-cookbook.rst:3418
msgid "Use a logging level based on command-line arguments"
msgstr ""

#: howto/logging-cookbook.rst:3419
msgid ""
"Dispatch to multiple subcommands in separate files, all logging at the same "
"level in a consistent way"
msgstr ""

#: howto/logging-cookbook.rst:3421
msgid "Make use of simple, minimal configuration"
msgstr ""

#: howto/logging-cookbook.rst:3423
msgid ""
"Suppose we have a command-line application whose job is to stop, start or "
"restart some services. This could be organised for the purposes of "
"illustration as a file ``app.py`` that is the main script for the "
"application, with individual commands implemented in ``start.py``, ``stop."
"py`` and ``restart.py``. Suppose further that we want to control the "
"verbosity of the application via a command-line argument, defaulting to "
"``logging.INFO``. Here's one way that ``app.py`` could be written::"
msgstr ""

#: howto/logging-cookbook.rst:3431
msgid ""
"import argparse\n"
"import importlib\n"
"import logging\n"
"import os\n"
"import sys\n"
"\n"
"def main(args=None):\n"
"    scriptname = os.path.basename(__file__)\n"
"    parser = argparse.ArgumentParser(scriptname)\n"
"    levels = ('DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL')\n"
"    parser.add_argument('--log-level', default='INFO', choices=levels)\n"
"    subparsers = parser.add_subparsers(dest='command',\n"
"                                       help='Available commands:')\n"
"    start_cmd = subparsers.add_parser('start', help='Start a service')\n"
"    start_cmd.add_argument('name', metavar='NAME',\n"
"                           help='Name of service to start')\n"
"    stop_cmd = subparsers.add_parser('stop',\n"
"                                     help='Stop one or more services')\n"
"    stop_cmd.add_argument('names', metavar='NAME', nargs='+',\n"
"                          help='Name of service to stop')\n"
"    restart_cmd = subparsers.add_parser('restart',\n"
"                                        help='Restart one or more "
"services')\n"
"    restart_cmd.add_argument('names', metavar='NAME', nargs='+',\n"
"                             help='Name of service to restart')\n"
"    options = parser.parse_args()\n"
"    # the code to dispatch commands could all be in this file. For the "
"purposes\n"
"    # of illustration only, we implement each command in a separate module.\n"
"    try:\n"
"        mod = importlib.import_module(options.command)\n"
"        cmd = getattr(mod, 'command')\n"
"    except (ImportError, AttributeError):\n"
"        print('Unable to find the code for command \\'%s\\'' % options."
"command)\n"
"        return 1\n"
"    # Could get fancy here and load configuration from file or dictionary\n"
"    logging.basicConfig(level=options.log_level,\n"
"                        format='%(levelname)s %(name)s %(message)s')\n"
"    cmd(options)\n"
"\n"
"if __name__ == '__main__':\n"
"    sys.exit(main())"
msgstr ""

#: howto/logging-cookbook.rst:3472
msgid ""
"And the ``start``, ``stop`` and ``restart`` commands can be implemented in "
"separate modules, like so for starting::"
msgstr ""

#: howto/logging-cookbook.rst:3475
msgid ""
"# start.py\n"
"import logging\n"
"\n"
"logger = logging.getLogger(__name__)\n"
"\n"
"def command(options):\n"
"    logger.debug('About to start %s', options.name)\n"
"    # actually do the command processing here ...\n"
"    logger.info('Started the \\'%s\\' service.', options.name)"
msgstr ""

#: howto/logging-cookbook.rst:3485
msgid "and thus for stopping::"
msgstr ""

#: howto/logging-cookbook.rst:3487
msgid ""
"# stop.py\n"
"import logging\n"
"\n"
"logger = logging.getLogger(__name__)\n"
"\n"
"def command(options):\n"
"    n = len(options.names)\n"
"    if n == 1:\n"
"        plural = ''\n"
"        services = '\\'%s\\'' % options.names[0]\n"
"    else:\n"
"        plural = 's'\n"
"        services = ', '.join('\\'%s\\'' % name for name in options.names)\n"
"        i = services.rfind(', ')\n"
"        services = services[:i] + ' and ' + services[i + 2:]\n"
"    logger.debug('About to stop %s', services)\n"
"    # actually do the command processing here ...\n"
"    logger.info('Stopped the %s service%s.', services, plural)"
msgstr ""

#: howto/logging-cookbook.rst:3506
msgid "and similarly for restarting::"
msgstr ""

#: howto/logging-cookbook.rst:3508
msgid ""
"# restart.py\n"
"import logging\n"
"\n"
"logger = logging.getLogger(__name__)\n"
"\n"
"def command(options):\n"
"    n = len(options.names)\n"
"    if n == 1:\n"
"        plural = ''\n"
"        services = '\\'%s\\'' % options.names[0]\n"
"    else:\n"
"        plural = 's'\n"
"        services = ', '.join('\\'%s\\'' % name for name in options.names)\n"
"        i = services.rfind(', ')\n"
"        services = services[:i] + ' and ' + services[i + 2:]\n"
"    logger.debug('About to restart %s', services)\n"
"    # actually do the command processing here ...\n"
"    logger.info('Restarted the %s service%s.', services, plural)"
msgstr ""

#: howto/logging-cookbook.rst:3527
msgid ""
"If we run this application with the default log level, we get output like "
"this:"
msgstr ""

#: howto/logging-cookbook.rst:3529
msgid ""
"$ python app.py start foo\n"
"INFO start Started the 'foo' service.\n"
"\n"
"$ python app.py stop foo bar\n"
"INFO stop Stopped the 'foo' and 'bar' services.\n"
"\n"
"$ python app.py restart foo bar baz\n"
"INFO restart Restarted the 'foo', 'bar' and 'baz' services."
msgstr ""

#: howto/logging-cookbook.rst:3540
msgid ""
"The first word is the logging level, and the second word is the module or "
"package name of the place where the event was logged."
msgstr ""

#: howto/logging-cookbook.rst:3543
msgid ""
"If we change the logging level, then we can change the information sent to "
"the log. For example, if we want more information:"
msgstr ""

#: howto/logging-cookbook.rst:3546
msgid ""
"$ python app.py --log-level DEBUG start foo\n"
"DEBUG start About to start foo\n"
"INFO start Started the 'foo' service.\n"
"\n"
"$ python app.py --log-level DEBUG stop foo bar\n"
"DEBUG stop About to stop 'foo' and 'bar'\n"
"INFO stop Stopped the 'foo' and 'bar' services.\n"
"\n"
"$ python app.py --log-level DEBUG restart foo bar baz\n"
"DEBUG restart About to restart 'foo', 'bar' and 'baz'\n"
"INFO restart Restarted the 'foo', 'bar' and 'baz' services."
msgstr ""

#: howto/logging-cookbook.rst:3560
msgid "And if we want less:"
msgstr ""

#: howto/logging-cookbook.rst:3562
msgid ""
"$ python app.py --log-level WARNING start foo\n"
"$ python app.py --log-level WARNING stop foo bar\n"
"$ python app.py --log-level WARNING restart foo bar baz"
msgstr ""

#: howto/logging-cookbook.rst:3568
msgid ""
"In this case, the commands don't print anything to the console, since "
"nothing at ``WARNING`` level or above is logged by them."
msgstr ""

#: howto/logging-cookbook.rst:3574
msgid "A Qt GUI for logging"
msgstr ""

#: howto/logging-cookbook.rst:3576
msgid ""
"A question that comes up from time to time is about how to log to a GUI "
"application. The `Qt <https://www.qt.io/>`_ framework is a popular cross-"
"platform UI framework with Python bindings using :pypi:`PySide2` or :pypi:"
"`PyQt5` libraries."
msgstr ""

#: howto/logging-cookbook.rst:3581
msgid ""
"The following example shows how to log to a Qt GUI. This introduces a simple "
"``QtHandler`` class which takes a callable, which should be a slot in the "
"main thread that does GUI updates. A worker thread is also created to show "
"how you can log to the GUI from both the UI itself (via a button for manual "
"logging) as well as a worker thread doing work in the background (here, just "
"logging messages at random levels with random short delays in between)."
msgstr ""

#: howto/logging-cookbook.rst:3588
msgid ""
"The worker thread is implemented using Qt's ``QThread`` class rather than "
"the :mod:`threading` module, as there are circumstances where one has to use "
"``QThread``, which offers better integration with other ``Qt`` components."
msgstr ""

#: howto/logging-cookbook.rst:3592
msgid ""
"The code should work with recent releases of any of ``PySide6``, ``PyQt6``, "
"``PySide2`` or ``PyQt5``. You should be able to adapt the approach to "
"earlier versions of Qt. Please refer to the comments in the code snippet for "
"more detailed information."
msgstr ""

#: howto/logging-cookbook.rst:3597
msgid ""
"import datetime\n"
"import logging\n"
"import random\n"
"import sys\n"
"import time\n"
"\n"
"# Deal with minor differences between different Qt packages\n"
"try:\n"
"    from PySide6 import QtCore, QtGui, QtWidgets\n"
"    Signal = QtCore.Signal\n"
"    Slot = QtCore.Slot\n"
"except ImportError:\n"
"    try:\n"
"        from PyQt6 import QtCore, QtGui, QtWidgets\n"
"        Signal = QtCore.pyqtSignal\n"
"        Slot = QtCore.pyqtSlot\n"
"    except ImportError:\n"
"        try:\n"
"            from PySide2 import QtCore, QtGui, QtWidgets\n"
"            Signal = QtCore.Signal\n"
"            Slot = QtCore.Slot\n"
"        except ImportError:\n"
"            from PyQt5 import QtCore, QtGui, QtWidgets\n"
"            Signal = QtCore.pyqtSignal\n"
"            Slot = QtCore.pyqtSlot\n"
"\n"
"logger = logging.getLogger(__name__)\n"
"\n"
"\n"
"#\n"
"# Signals need to be contained in a QObject or subclass in order to be "
"correctly\n"
"# initialized.\n"
"#\n"
"class Signaller(QtCore.QObject):\n"
"    signal = Signal(str, logging.LogRecord)\n"
"\n"
"#\n"
"# Output to a Qt GUI is only supposed to happen on the main thread. So, "
"this\n"
"# handler is designed to take a slot function which is set up to run in the "
"main\n"
"# thread. In this example, the function takes a string argument which is a\n"
"# formatted log message, and the log record which generated it. The "
"formatted\n"
"# string is just a convenience - you could format a string for output any "
"way\n"
"# you like in the slot function itself.\n"
"#\n"
"# You specify the slot function to do whatever GUI updates you want. The "
"handler\n"
"# doesn't know or care about specific UI elements.\n"
"#\n"
"class QtHandler(logging.Handler):\n"
"    def __init__(self, slotfunc, *args, **kwargs):\n"
"        super().__init__(*args, **kwargs)\n"
"        self.signaller = Signaller()\n"
"        self.signaller.signal.connect(slotfunc)\n"
"\n"
"    def emit(self, record):\n"
"        s = self.format(record)\n"
"        self.signaller.signal.emit(s, record)\n"
"\n"
"#\n"
"# This example uses QThreads, which means that the threads at the Python "
"level\n"
"# are named something like \"Dummy-1\". The function below gets the Qt name "
"of the\n"
"# current thread.\n"
"#\n"
"def ctname():\n"
"    return QtCore.QThread.currentThread().objectName()\n"
"\n"
"\n"
"#\n"
"# Used to generate random levels for logging.\n"
"#\n"
"LEVELS = (logging.DEBUG, logging.INFO, logging.WARNING, logging.ERROR,\n"
"          logging.CRITICAL)\n"
"\n"
"#\n"
"# This worker class represents work that is done in a thread separate to "
"the\n"
"# main thread. The way the thread is kicked off to do work is via a button "
"press\n"
"# that connects to a slot in the worker.\n"
"#\n"
"# Because the default threadName value in the LogRecord isn't much use, we "
"add\n"
"# a qThreadName which contains the QThread name as computed above, and pass "
"that\n"
"# value in an \"extra\" dictionary which is used to update the LogRecord "
"with the\n"
"# QThread name.\n"
"#\n"
"# This example worker just outputs messages sequentially, interspersed with\n"
"# random delays of the order of a few seconds.\n"
"#\n"
"class Worker(QtCore.QObject):\n"
"    @Slot()\n"
"    def start(self):\n"
"        extra = {'qThreadName': ctname() }\n"
"        logger.debug('Started work', extra=extra)\n"
"        i = 1\n"
"        # Let the thread run until interrupted. This allows reasonably "
"clean\n"
"        # thread termination.\n"
"        while not QtCore.QThread.currentThread().isInterruptionRequested():\n"
"            delay = 0.5 + random.random() * 2\n"
"            time.sleep(delay)\n"
"            try:\n"
"                if random.random() < 0.1:\n"
"                    raise ValueError('Exception raised: %d' % i)\n"
"                else:\n"
"                    level = random.choice(LEVELS)\n"
"                    logger.log(level, 'Message after delay of %3.1f: %d', "
"delay, i, extra=extra)\n"
"            except ValueError as e:\n"
"                logger.exception('Failed: %s', e, extra=extra)\n"
"            i += 1\n"
"\n"
"#\n"
"# Implement a simple UI for this cookbook example. This contains:\n"
"#\n"
"# * A read-only text edit window which holds formatted log messages\n"
"# * A button to start work and log stuff in a separate thread\n"
"# * A button to log something from the main thread\n"
"# * A button to clear the log window\n"
"#\n"
"class Window(QtWidgets.QWidget):\n"
"\n"
"    COLORS = {\n"
"        logging.DEBUG: 'black',\n"
"        logging.INFO: 'blue',\n"
"        logging.WARNING: 'orange',\n"
"        logging.ERROR: 'red',\n"
"        logging.CRITICAL: 'purple',\n"
"    }\n"
"\n"
"    def __init__(self, app):\n"
"        super().__init__()\n"
"        self.app = app\n"
"        self.textedit = te = QtWidgets.QPlainTextEdit(self)\n"
"        # Set whatever the default monospace font is for the platform\n"
"        f = QtGui.QFont('nosuchfont')\n"
"        if hasattr(f, 'Monospace'):\n"
"            f.setStyleHint(f.Monospace)\n"
"        else:\n"
"            f.setStyleHint(f.StyleHint.Monospace)  # for Qt6\n"
"        te.setFont(f)\n"
"        te.setReadOnly(True)\n"
"        PB = QtWidgets.QPushButton\n"
"        self.work_button = PB('Start background work', self)\n"
"        self.log_button = PB('Log a message at a random level', self)\n"
"        self.clear_button = PB('Clear log window', self)\n"
"        self.handler = h = QtHandler(self.update_status)\n"
"        # Remember to use qThreadName rather than threadName in the format "
"string.\n"
"        fs = '%(asctime)s %(qThreadName)-12s %(levelname)-8s %(message)s'\n"
"        formatter = logging.Formatter(fs)\n"
"        h.setFormatter(formatter)\n"
"        logger.addHandler(h)\n"
"        # Set up to terminate the QThread when we exit\n"
"        app.aboutToQuit.connect(self.force_quit)\n"
"\n"
"        # Lay out all the widgets\n"
"        layout = QtWidgets.QVBoxLayout(self)\n"
"        layout.addWidget(te)\n"
"        layout.addWidget(self.work_button)\n"
"        layout.addWidget(self.log_button)\n"
"        layout.addWidget(self.clear_button)\n"
"        self.setFixedSize(900, 400)\n"
"\n"
"        # Connect the non-worker slots and signals\n"
"        self.log_button.clicked.connect(self.manual_update)\n"
"        self.clear_button.clicked.connect(self.clear_display)\n"
"\n"
"        # Start a new worker thread and connect the slots for the worker\n"
"        self.start_thread()\n"
"        self.work_button.clicked.connect(self.worker.start)\n"
"        # Once started, the button should be disabled\n"
"        self.work_button.clicked.connect(lambda : self.work_button."
"setEnabled(False))\n"
"\n"
"    def start_thread(self):\n"
"        self.worker = Worker()\n"
"        self.worker_thread = QtCore.QThread()\n"
"        self.worker.setObjectName('Worker')\n"
"        self.worker_thread.setObjectName('WorkerThread')  # for qThreadName\n"
"        self.worker.moveToThread(self.worker_thread)\n"
"        # This will start an event loop in the worker thread\n"
"        self.worker_thread.start()\n"
"\n"
"    def kill_thread(self):\n"
"        # Just tell the worker to stop, then tell it to quit and wait for "
"that\n"
"        # to happen\n"
"        self.worker_thread.requestInterruption()\n"
"        if self.worker_thread.isRunning():\n"
"            self.worker_thread.quit()\n"
"            self.worker_thread.wait()\n"
"        else:\n"
"            print('worker has already exited.')\n"
"\n"
"    def force_quit(self):\n"
"        # For use when the window is closed\n"
"        if self.worker_thread.isRunning():\n"
"            self.kill_thread()\n"
"\n"
"    # The functions below update the UI and run in the main thread because\n"
"    # that's where the slots are set up\n"
"\n"
"    @Slot(str, logging.LogRecord)\n"
"    def update_status(self, status, record):\n"
"        color = self.COLORS.get(record.levelno, 'black')\n"
"        s = '<pre><font color=\"%s\">%s</font></pre>' % (color, status)\n"
"        self.textedit.appendHtml(s)\n"
"\n"
"    @Slot()\n"
"    def manual_update(self):\n"
"        # This function uses the formatted message passed in, but also uses\n"
"        # information from the record to format the message in an "
"appropriate\n"
"        # color according to its severity (level).\n"
"        level = random.choice(LEVELS)\n"
"        extra = {'qThreadName': ctname() }\n"
"        logger.log(level, 'Manually logged!', extra=extra)\n"
"\n"
"    @Slot()\n"
"    def clear_display(self):\n"
"        self.textedit.clear()\n"
"\n"
"\n"
"def main():\n"
"    QtCore.QThread.currentThread().setObjectName('MainThread')\n"
"    logging.getLogger().setLevel(logging.DEBUG)\n"
"    app = QtWidgets.QApplication(sys.argv)\n"
"    example = Window(app)\n"
"    example.show()\n"
"    if hasattr(app, 'exec'):\n"
"        rc = app.exec()\n"
"    else:\n"
"        rc = app.exec_()\n"
"    sys.exit(rc)\n"
"\n"
"if __name__=='__main__':\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:3829
msgid "Logging to syslog with RFC5424 support"
msgstr ""

#: howto/logging-cookbook.rst:3831
msgid ""
"Although :rfc:`5424` dates from 2009, most syslog servers are configured by "
"default to use the older :rfc:`3164`, which hails from 2001. When "
"``logging`` was added to Python in 2003, it supported the earlier (and only "
"existing) protocol at the time. Since RFC5424 came out, as there has not "
"been widespread deployment of it in syslog servers, the :class:`~logging."
"handlers.SysLogHandler` functionality has not been updated."
msgstr ""

#: howto/logging-cookbook.rst:3838
msgid ""
"RFC 5424 contains some useful features such as support for structured data, "
"and if you need to be able to log to a syslog server with support for it, "
"you can do so with a subclassed handler which looks something like this::"
msgstr ""

#: howto/logging-cookbook.rst:3842
msgid ""
"import datetime\n"
"import logging.handlers\n"
"import re\n"
"import socket\n"
"import time\n"
"\n"
"class SysLogHandler5424(logging.handlers.SysLogHandler):\n"
"\n"
"    tz_offset = re.compile(r'([+-]\\d{2})(\\d{2})$')\n"
"    escaped = re.compile(r'([\\]\"\\\\])')\n"
"\n"
"    def __init__(self, *args, **kwargs):\n"
"        self.msgid = kwargs.pop('msgid', None)\n"
"        self.appname = kwargs.pop('appname', None)\n"
"        super().__init__(*args, **kwargs)\n"
"\n"
"    def format(self, record):\n"
"        version = 1\n"
"        asctime = datetime.datetime.fromtimestamp(record.created)."
"isoformat()\n"
"        m = self.tz_offset.match(time.strftime('%z'))\n"
"        has_offset = False\n"
"        if m and time.timezone:\n"
"            hrs, mins = m.groups()\n"
"            if int(hrs) or int(mins):\n"
"                has_offset = True\n"
"        if not has_offset:\n"
"            asctime += 'Z'\n"
"        else:\n"
"            asctime += f'{hrs}:{mins}'\n"
"        try:\n"
"            hostname = socket.gethostname()\n"
"        except Exception:\n"
"            hostname = '-'\n"
"        appname = self.appname or '-'\n"
"        procid = record.process\n"
"        msgid = '-'\n"
"        msg = super().format(record)\n"
"        sdata = '-'\n"
"        if hasattr(record, 'structured_data'):\n"
"            sd = record.structured_data\n"
"            # This should be a dict where the keys are SD-ID and the value "
"is a\n"
"            # dict mapping PARAM-NAME to PARAM-VALUE (refer to the RFC for "
"what these\n"
"            # mean)\n"
"            # There's no error checking here - it's purely for illustration, "
"and you\n"
"            # can adapt this code for use in production environments\n"
"            parts = []\n"
"\n"
"            def replacer(m):\n"
"                g = m.groups()\n"
"                return '\\\\' + g[0]\n"
"\n"
"            for sdid, dv in sd.items():\n"
"                part = f'[{sdid}'\n"
"                for k, v in dv.items():\n"
"                    s = str(v)\n"
"                    s = self.escaped.sub(replacer, s)\n"
"                    part += f' {k}=\"{s}\"'\n"
"                part += ']'\n"
"                parts.append(part)\n"
"            sdata = ''.join(parts)\n"
"        return f'{version} {asctime} {hostname} {appname} {procid} {msgid} "
"{sdata} {msg}'"
msgstr ""

#: howto/logging-cookbook.rst:3904
msgid ""
"You'll need to be familiar with RFC 5424 to fully understand the above code, "
"and it may be that you have slightly different needs (e.g. for how you pass "
"structural data to the log). Nevertheless, the above should be adaptable to "
"your speciric needs. With the above handler, you'd pass structured data "
"using something like this::"
msgstr ""

#: howto/logging-cookbook.rst:3909
msgid ""
"sd = {\n"
"    'foo@12345': {'bar': 'baz', 'baz': 'bozz', 'fizz': r'buzz'},\n"
"    'foo@54321': {'rab': 'baz', 'zab': 'bozz', 'zzif': r'buzz'}\n"
"}\n"
"extra = {'structured_data': sd}\n"
"i = 1\n"
"logger.debug('Message %d', i, extra=extra)"
msgstr ""

#: howto/logging-cookbook.rst:3918
msgid "How to treat a logger like an output stream"
msgstr ""

#: howto/logging-cookbook.rst:3920
msgid ""
"Sometimes, you need to interface to a third-party API which expects a file-"
"like object to write to, but you want to direct the API's output to a "
"logger. You can do this using a class which wraps a logger with a file-like "
"API. Here's a short script illustrating such a class:"
msgstr ""

#: howto/logging-cookbook.rst:3925
msgid ""
"import logging\n"
"\n"
"class LoggerWriter:\n"
"    def __init__(self, logger, level):\n"
"        self.logger = logger\n"
"        self.level = level\n"
"\n"
"    def write(self, message):\n"
"        if message != '\\n':  # avoid printing bare newlines, if you like\n"
"            self.logger.log(self.level, message)\n"
"\n"
"    def flush(self):\n"
"        # doesn't actually do anything, but might be expected of a file-"
"like\n"
"        # object - so optional depending on your situation\n"
"        pass\n"
"\n"
"    def close(self):\n"
"        # doesn't actually do anything, but might be expected of a file-"
"like\n"
"        # object - so optional depending on your situation. You might want\n"
"        # to set a flag so that later calls to write raise an exception\n"
"        pass\n"
"\n"
"def main():\n"
"    logging.basicConfig(level=logging.DEBUG)\n"
"    logger = logging.getLogger('demo')\n"
"    info_fp = LoggerWriter(logger, logging.INFO)\n"
"    debug_fp = LoggerWriter(logger, logging.DEBUG)\n"
"    print('An INFO message', file=info_fp)\n"
"    print('A DEBUG message', file=debug_fp)\n"
"\n"
"if __name__ == \"__main__\":\n"
"    main()"
msgstr ""

#: howto/logging-cookbook.rst:3960
msgid "When this script is run, it prints"
msgstr ""

#: howto/logging-cookbook.rst:3962
msgid ""
"INFO:demo:An INFO message\n"
"DEBUG:demo:A DEBUG message"
msgstr ""

#: howto/logging-cookbook.rst:3967
msgid ""
"You could also use ``LoggerWriter`` to redirect ``sys.stdout`` and ``sys."
"stderr`` by doing something like this:"
msgstr ""

#: howto/logging-cookbook.rst:3970
msgid ""
"import sys\n"
"\n"
"sys.stdout = LoggerWriter(logger, logging.INFO)\n"
"sys.stderr = LoggerWriter(logger, logging.WARNING)"
msgstr ""

#: howto/logging-cookbook.rst:3977
msgid ""
"You should do this *after* configuring logging for your needs. In the above "
"example, the :func:`~logging.basicConfig` call does this (using the ``sys."
"stderr`` value *before* it is overwritten by a ``LoggerWriter`` instance). "
"Then, you'd get this kind of result:"
msgstr ""

#: howto/logging-cookbook.rst:3982
msgid ""
">>> print('Foo')\n"
"INFO:demo:Foo\n"
">>> print('Bar', file=sys.stderr)\n"
"WARNING:demo:Bar\n"
">>>"
msgstr ""

#: howto/logging-cookbook.rst:3990
msgid ""
"Of course, the examples above show output according to the format used by :"
"func:`~logging.basicConfig`, but you can use a different formatter when you "
"configure logging."
msgstr ""

#: howto/logging-cookbook.rst:3994
msgid ""
"Note that with the above scheme, you are somewhat at the mercy of buffering "
"and the sequence of write calls which you are intercepting. For example, "
"with the definition of ``LoggerWriter`` above, if you have the snippet"
msgstr ""

#: howto/logging-cookbook.rst:3998
msgid ""
"sys.stderr = LoggerWriter(logger, logging.WARNING)\n"
"1 / 0"
msgstr ""

#: howto/logging-cookbook.rst:4003
msgid "then running the script results in"
msgstr ""

#: howto/logging-cookbook.rst:4005
msgid ""
"WARNING:demo:Traceback (most recent call last):\n"
"\n"
"WARNING:demo:  File \"/home/runner/cookbook-loggerwriter/test.py\", line 53, "
"in <module>\n"
"\n"
"WARNING:demo:\n"
"WARNING:demo:main()\n"
"WARNING:demo:  File \"/home/runner/cookbook-loggerwriter/test.py\", line 49, "
"in main\n"
"\n"
"WARNING:demo:\n"
"WARNING:demo:1 / 0\n"
"WARNING:demo:ZeroDivisionError\n"
"WARNING:demo::\n"
"WARNING:demo:division by zero"
msgstr ""

#: howto/logging-cookbook.rst:4021
msgid ""
"As you can see, this output isn't ideal. That's because the underlying code "
"which writes to ``sys.stderr`` makes multiple writes, each of which results "
"in a separate logged line (for example, the last three lines above). To get "
"around this problem, you need to buffer things and only output log lines "
"when newlines are seen. Let's use a slightly better implementation of "
"``LoggerWriter``:"
msgstr ""

#: howto/logging-cookbook.rst:4027
msgid ""
"class BufferingLoggerWriter(LoggerWriter):\n"
"    def __init__(self, logger, level):\n"
"        super().__init__(logger, level)\n"
"        self.buffer = ''\n"
"\n"
"    def write(self, message):\n"
"        if '\\n' not in message:\n"
"            self.buffer += message\n"
"        else:\n"
"            parts = message.split('\\n')\n"
"            if self.buffer:\n"
"                s = self.buffer + parts.pop(0)\n"
"                self.logger.log(self.level, s)\n"
"            self.buffer = parts.pop()\n"
"            for part in parts:\n"
"                self.logger.log(self.level, part)"
msgstr ""

#: howto/logging-cookbook.rst:4046
msgid ""
"This just buffers up stuff until a newline is seen, and then logs complete "
"lines. With this approach, you get better output:"
msgstr ""

#: howto/logging-cookbook.rst:4049
msgid ""
"WARNING:demo:Traceback (most recent call last):\n"
"WARNING:demo:  File \"/home/runner/cookbook-loggerwriter/main.py\", line 55, "
"in <module>\n"
"WARNING:demo:    main()\n"
"WARNING:demo:  File \"/home/runner/cookbook-loggerwriter/main.py\", line 52, "
"in main\n"
"WARNING:demo:    1/0\n"
"WARNING:demo:ZeroDivisionError: division by zero"
msgstr ""

#: howto/logging-cookbook.rst:4062
msgid "Patterns to avoid"
msgstr ""

#: howto/logging-cookbook.rst:4064
msgid ""
"Although the preceding sections have described ways of doing things you "
"might need to do or deal with, it is worth mentioning some usage patterns "
"which are *unhelpful*, and which should therefore be avoided in most cases. "
"The following sections are in no particular order."
msgstr ""

#: howto/logging-cookbook.rst:4070
msgid "Opening the same log file multiple times"
msgstr ""

#: howto/logging-cookbook.rst:4072
msgid ""
"On Windows, you will generally not be able to open the same file multiple "
"times as this will lead to a \"file is in use by another process\" error. "
"However, on POSIX platforms you'll not get any errors if you open the same "
"file multiple times. This could be done accidentally, for example by:"
msgstr ""

#: howto/logging-cookbook.rst:4077
msgid ""
"Adding a file handler more than once which references the same file (e.g. by "
"a copy/paste/forget-to-change error)."
msgstr ""

#: howto/logging-cookbook.rst:4080
msgid ""
"Opening two files that look different, as they have different names, but are "
"the same because one is a symbolic link to the other."
msgstr ""

#: howto/logging-cookbook.rst:4083
msgid ""
"Forking a process, following which both parent and child have a reference to "
"the same file. This might be through use of the :mod:`multiprocessing` "
"module, for example."
msgstr ""

#: howto/logging-cookbook.rst:4087
msgid ""
"Opening a file multiple times might *appear* to work most of the time, but "
"can lead to a number of problems in practice:"
msgstr ""

#: howto/logging-cookbook.rst:4090
msgid ""
"Logging output can be garbled because multiple threads or processes try to "
"write to the same file. Although logging guards against concurrent use of "
"the same handler instance by multiple threads, there is no such protection "
"if concurrent writes are attempted by two different threads using two "
"different handler instances which happen to point to the same file."
msgstr ""

#: howto/logging-cookbook.rst:4096
msgid ""
"An attempt to delete a file (e.g. during file rotation) silently fails, "
"because there is another reference pointing to it. This can lead to "
"confusion and wasted debugging time - log entries end up in unexpected "
"places, or are lost altogether. Or a file that was supposed to be moved "
"remains in place, and grows in size unexpectedly despite size-based rotation "
"being supposedly in place."
msgstr ""

#: howto/logging-cookbook.rst:4103
msgid ""
"Use the techniques outlined in :ref:`multiple-processes` to circumvent such "
"issues."
msgstr ""

#: howto/logging-cookbook.rst:4107
msgid "Using loggers as attributes in a class or passing them as parameters"
msgstr ""

#: howto/logging-cookbook.rst:4109
msgid ""
"While there might be unusual cases where you'll need to do this, in general "
"there is no point because loggers are singletons. Code can always access a "
"given logger instance by name using ``logging.getLogger(name)``, so passing "
"instances around and holding them as instance attributes is pointless. Note "
"that in other languages such as Java and C#, loggers are often static class "
"attributes. However, this pattern doesn't make sense in Python, where the "
"module (and not the class) is the unit of software decomposition."
msgstr ""

#: howto/logging-cookbook.rst:4118
msgid ""
"Adding handlers other than :class:`~logging.NullHandler` to a logger in a "
"library"
msgstr ""

#: howto/logging-cookbook.rst:4120
msgid ""
"Configuring logging by adding handlers, formatters and filters is the "
"responsibility of the application developer, not the library developer. If "
"you are maintaining a library, ensure that you don't add handlers to any of "
"your loggers other than a :class:`~logging.NullHandler` instance."
msgstr ""

#: howto/logging-cookbook.rst:4126
msgid "Creating a lot of loggers"
msgstr ""

#: howto/logging-cookbook.rst:4128
msgid ""
"Loggers are singletons that are never freed during a script execution, and "
"so creating lots of loggers will use up memory which can't then be freed. "
"Rather than create a logger per e.g. file processed or network connection "
"made, use the :ref:`existing mechanisms <context-info>` for passing "
"contextual information into your logs and restrict the loggers created to "
"those describing areas within your application (generally modules, but "
"occasionally slightly more fine-grained than that)."
msgstr ""

#: howto/logging-cookbook.rst:4139
msgid "Other resources"
msgstr ""

#: howto/logging-cookbook.rst:4143
msgid "Module :mod:`logging`"
msgstr ""

#: howto/logging-cookbook.rst:4144
msgid "API reference for the logging module."
msgstr ""

#: howto/logging-cookbook.rst:4146
msgid "Module :mod:`logging.config`"
msgstr ""

#: howto/logging-cookbook.rst:4147
msgid "Configuration API for the logging module."
msgstr ""

#: howto/logging-cookbook.rst:4149
msgid "Module :mod:`logging.handlers`"
msgstr ""

#: howto/logging-cookbook.rst:4150
msgid "Useful handlers included with the logging module."
msgstr ""

#: howto/logging-cookbook.rst:4152
msgid ":ref:`Basic Tutorial <logging-basic-tutorial>`"
msgstr ""

#: howto/logging-cookbook.rst:4154
msgid ":ref:`Advanced Tutorial <logging-advanced-tutorial>`"
msgstr ""