Allow \watch to display query execution time if \timing is enabled.

Previously \watch could not display the query execution time even
when \timing was enabled because it used PSQLexec instead of
SendQuery and that function didn't support \timing. This patch
introduces PSQLexecWatch and changes \watch so as to use it, instead.
PSQLexecWatch is the function to run the query, print its results and
display how long it took (only when \timing is enabled).

This patch also changes --echo-hidden so that it doesn't print
the query that \watch executes. Since \watch cannot execute
backslash command queries, they should not be printed even
when --echo-hidden is set.

Patch by me, review by Heikki Linnakangas and Michael Paquier

1 files changed, 96 insertions, 0 deletions

diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 676e2680af6..0f83799f7e0 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -497,6 +497,102 @@ PSQLexec(const char *query, bool start_xact)
 }
 
 
+/*
+ * PSQLexecWatch
+ *
+ * This function is used for \watch command to send the query to
+ * the server and print out the results.
+ *
+ * Returns 1 if the query executed successfully, 0 if it cannot be repeated,
+ * e.g., because of the interrupt, -1 on error.
+ */
+int
+PSQLexecWatch(const char *query, const printQueryOpt *opt)
+{
+	PGresult   *res;
+	double	elapsed_msec = 0;
+	instr_time	before;
+	instr_time	after;
+
+	if (!pset.db)
+	{
+		psql_error("You are currently not connected to a database.\n");
+		return 0;
+	}
+
+	SetCancelConn();
+
+	if (pset.timing)
+		INSTR_TIME_SET_CURRENT(before);
+
+	res = PQexec(pset.db, query);
+
+	ResetCancelConn();
+
+	if (!AcceptResult(res))
+	{
+		PQclear(res);
+		return 0;
+	}
+
+	if (pset.timing)
+	{
+		INSTR_TIME_SET_CURRENT(after);
+		INSTR_TIME_SUBTRACT(after, before);
+		elapsed_msec = INSTR_TIME_GET_MILLISEC(after);
+	}
+
+	/*
+	 * If SIGINT is sent while the query is processing, the interrupt
+	 * will be consumed.  The user's intention, though, is to cancel
+	 * the entire watch process, so detect a sent cancellation request and
+	 * exit in this case.
+	 */
+	if (cancel_pressed)
+	{
+		PQclear(res);
+		return 0;
+	}
+
+	switch (PQresultStatus(res))
+	{
+		case PGRES_TUPLES_OK:
+			printQuery(res, opt, pset.queryFout, pset.logfile);
+			break;
+
+		case PGRES_COMMAND_OK:
+			fprintf(pset.queryFout, "%s\n%s\n\n", opt->title, PQcmdStatus(res));
+			break;
+
+		case PGRES_EMPTY_QUERY:
+			psql_error(_("\\watch cannot be used with an empty query\n"));
+			PQclear(res);
+			return -1;
+
+		case PGRES_COPY_OUT:
+		case PGRES_COPY_IN:
+		case PGRES_COPY_BOTH:
+			psql_error(_("\\watch cannot be used with COPY\n"));
+			PQclear(res);
+			return -1;
+
+		default:
+			psql_error(_("unexpected result status for \\watch\n"));
+			PQclear(res);
+			return -1;
+	}
+
+	PQclear(res);
+
+	fflush(pset.queryFout);
+
+	/* Possible microtiming output */
+	if (pset.timing)
+		printf(_("Time: %.3f ms\n"), elapsed_msec);
+
+	return 1;
+}
+
 
 /*
  * PrintNotifications: check for asynchronous notifications, and print them out