Loop calling CallNamedPipe() several times in case it fails,

since it can be transient failures, causing kill() to not
properly send signals.

Original patch from Steve Marshall, modified by me.

diff --git a/src/port/kill.c b/src/port/kill.c
index 0b6ee0d2ed852f228b5ff8eabd524a5f61b9c7b6..5a2faaa751cea57edc89f3dfd591d133d38b48e0 100644 (file)
--- a/src/port/kill.c
+++ b/src/port/kill.c
@@ -25,6 +25,7 @@ pgkill(int pid, int sig)
        BYTE            sigData = sig;
        BYTE            sigRet = 0;
        DWORD           bytes;
+       int                     pipe_tries;
 
        /* we allow signal 0 here, but it will be ignored in pg_queue_signal */
        if (sig >= PG_SIGNAL_COUNT || sig < 0)
@@ -39,23 +40,33 @@ pgkill(int pid, int sig)
                return -1;
        }
        snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%u", pid);
-       if (!CallNamedPipe(pipename, &sigData, 1, &sigRet, 1, &bytes, 1000))
-       {
-               if (GetLastError() == ERROR_FILE_NOT_FOUND)
-                       errno = ESRCH;
-               else if (GetLastError() == ERROR_ACCESS_DENIED)
-                       errno = EPERM;
-               else
-                       errno = EINVAL;
-               return -1;
-       }
-       if (bytes != 1 || sigRet != sig)
+
+       /*
+        * Writing data to the named pipe can fail for transient reasons.
+        * Therefore, it is useful to retry if it fails.  The maximum number of
+        * calls to make was empirically determined from a 90-hour notification
+        * stress test.
+        */
+       for (pipe_tries = 0; pipe_tries < 3; pipe_tries++)
        {
-               errno = ESRCH;
-               return -1;
+               if (CallNamedPipe(pipename, &sigData, 1, &sigRet, 1, &bytes, 1000))
+               {
+                       if (bytes != 1 || sigRet != sig)
+                       {
+                               errno = ESRCH;
+                               return -1;
+                       }
+                       return 0;
+               }
        }
 
-       return 0;
+       if (GetLastError() == ERROR_FILE_NOT_FOUND)
+               errno = ESRCH;
+       else if (GetLastError() == ERROR_ACCESS_DENIED)
+               errno = EPERM;
+       else
+               errno = EINVAL;
+       return -1;
 }
 
 #endif