psql: Refactor SendQuery()

This breaks out the fetch-it-all-and-print case in SendQuery() into a
separate function.  This makes the code more similar to the other
cases \gdesc and run query with FETCH_COUNT, and makes SendQuery()
itself a bit smaller.

Extracted from a larger patch with more changes in this area to
follow.

Author: Fabien COELHO <coelho@cri.ensmp.fr>
Discussion: https://www.postgresql.org/message-id/flat/alpine.DEB.2.21.1904132231510.8961@lancre

diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index d65b9a124f2d36cc822c8f2e49bca9dbcd664d01..c9847c8f9a02745d8d5553095d2814b973479f06 100644 (file)
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -32,6 +32,7 @@
 
 static bool DescribeQuery(const char *query, double *elapsed_msec);
 static bool ExecQueryUsingCursor(const char *query, double *elapsed_msec);
+static bool ExecQueryAndProcessResult(const char *query, double *elapsed_msec, bool *svpt_gone_p);
 static bool command_no_begin(const char *query);
 static bool is_select_command(const char *query);
 
@@ -1195,12 +1196,12 @@ bool
 SendQuery(const char *query)
 {
    bool        timing = pset.timing;
-   PGresult   *result;
    PGTransactionStatusType transaction_status;
    double      elapsed_msec = 0;
    bool        OK = false;
    int         i;
    bool        on_error_rollback_savepoint = false;
+   bool        svpt_gone = false;
 
    if (!pset.db)
    {
@@ -1247,6 +1248,8 @@ SendQuery(const char *query)
        !pset.autocommit &&
        !command_no_begin(query))
    {
+       PGresult   *result;
+
        result = PQexec(pset.db, "BEGIN");
        if (PQresultStatus(result) != PGRES_COMMAND_OK)
        {
@@ -1264,6 +1267,8 @@ SendQuery(const char *query)
        (pset.cur_cmd_interactive ||
         pset.on_error_rollback == PSQL_ERROR_ROLLBACK_ON))
    {
+       PGresult   *result;
+
        result = PQexec(pset.db, "SAVEPOINT pg_psql_temporary_savepoint");
        if (PQresultStatus(result) != PGRES_COMMAND_OK)
        {
@@ -1281,41 +1286,18 @@ SendQuery(const char *query)
        /* Describe query's result columns, without executing it */
        OK = DescribeQuery(query, &elapsed_msec);
        ResetCancelConn();
-       result = NULL;          /* PQclear(NULL) does nothing */
    }
    else if (pset.fetch_count <= 0 || pset.gexec_flag ||
             pset.crosstab_flag || !is_select_command(query))
    {
        /* Default fetch-it-all-and-print mode */
-       instr_time  before,
-                   after;
-
-       if (timing)
-           INSTR_TIME_SET_CURRENT(before);
-
-       result = PQexec(pset.db, query);
-
-       /* these operations are included in the timing result: */
-       ResetCancelConn();
-       OK = ProcessResult(&result);
-
-       if (timing)
-       {
-           INSTR_TIME_SET_CURRENT(after);
-           INSTR_TIME_SUBTRACT(after, before);
-           elapsed_msec = INSTR_TIME_GET_MILLISEC(after);
-       }
-
-       /* but printing result isn't: */
-       if (OK && result)
-           OK = PrintQueryResult(result);
+       OK = ExecQueryAndProcessResult(query, &elapsed_msec, &svpt_gone);
    }
    else
    {
        /* Fetch-in-segments mode */
        OK = ExecQueryUsingCursor(query, &elapsed_msec);
        ResetCancelConn();
-       result = NULL;          /* PQclear(NULL) does nothing */
    }
 
    if (!OK && pset.echo == PSQL_ECHO_ERRORS)
@@ -1340,20 +1322,11 @@ SendQuery(const char *query)
                break;
 
            case PQTRANS_INTRANS:
-
                /*
-                * Do nothing if they are messing with savepoints themselves:
-                * If the user did COMMIT AND CHAIN, RELEASE or ROLLBACK, our
-                * savepoint is gone. If they issued a SAVEPOINT, releasing
-                * ours would remove theirs.
+                * Release our savepoint, but do nothing if they are messing
+                * with savepoints themselves
                 */
-               if (result &&
-                   (strcmp(PQcmdStatus(result), "COMMIT") == 0 ||
-                    strcmp(PQcmdStatus(result), "SAVEPOINT") == 0 ||
-                    strcmp(PQcmdStatus(result), "RELEASE") == 0 ||
-                    strcmp(PQcmdStatus(result), "ROLLBACK") == 0))
-                   svptcmd = NULL;
-               else
+               if (!svpt_gone)
                    svptcmd = "RELEASE pg_psql_temporary_savepoint";
                break;
 
@@ -1379,7 +1352,6 @@ SendQuery(const char *query)
                ClearOrSaveResult(svptres);
                OK = false;
 
-               PQclear(result);
                ResetCancelConn();
                goto sendquery_cleanup;
            }
@@ -1387,8 +1359,6 @@ SendQuery(const char *query)
        }
    }
 
-   ClearOrSaveResult(result);
-
    /* Possible microtiming output */
    if (timing)
        PrintTiming(elapsed_msec);
@@ -1565,6 +1535,60 @@ DescribeQuery(const char *query, double *elapsed_msec)
 }
 
 
+/*
+ * ExecQueryAndProcessResults: SendQuery() subroutine for the normal way to
+ * send a query
+ */
+static bool
+ExecQueryAndProcessResult(const char *query, double *elapsed_msec, bool *svpt_gone_p)
+{
+   bool        timing = pset.timing;
+   bool        OK;
+   instr_time  before,
+               after;
+   PGresult   *result;
+
+   if (timing)
+       INSTR_TIME_SET_CURRENT(before);
+
+   result = PQexec(pset.db, query);
+
+   /* these operations are included in the timing result: */
+   ResetCancelConn();
+   OK = ProcessResult(&result);
+
+   if (timing)
+   {
+       INSTR_TIME_SET_CURRENT(after);
+       INSTR_TIME_SUBTRACT(after, before);
+       *elapsed_msec = INSTR_TIME_GET_MILLISEC(after);
+   }
+
+   /* but printing result isn't: */
+   if (OK && result)
+       OK = PrintQueryResult(result);
+
+   /*
+    * Check if the user ran any command that would destroy our internal
+    * savepoint: If the user did COMMIT AND CHAIN, RELEASE or ROLLBACK, our
+    * savepoint is gone. If they issued a SAVEPOINT, releasing ours would
+    * remove theirs.
+    */
+   if (result && svpt_gone_p)
+   {
+       const char *cmd = PQcmdStatus(result);
+       *svpt_gone_p = (strcmp(cmd, "COMMIT") == 0 ||
+                       strcmp(cmd, "SAVEPOINT") == 0 ||
+                       strcmp(cmd, "RELEASE") == 0 ||
+                       strcmp(cmd, "ROLLBACK") == 0);
+   }
+
+   ClearOrSaveResult(result);
+
+   return OK;
+}
+
+
 /*
  * ExecQueryUsingCursor: run a SELECT-like query using a cursor
  *