Remove redundant gettimeofday() calls to the extent practical without

changing semantics too much.  statement_timestamp is now set immediately
upon receipt of a client command message, and the various places that used
to do their own gettimeofday() calls to mark command startup are referenced
to that instead.  I have also made stats_command_string use that same
value for pg_stat_activity.query_start for both the command itself and
its eventual replacement by <IDLE> or <idle in transaction>.  There was
some debate about that, but no argument that seemed convincing enough to
justify an extra gettimeofday() call.

2 files changed, 18 insertions, 8 deletions

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index f6949f14377..a340a91fed2 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2006, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.129 2006/06/19 01:51:21 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.130 2006/06/20 22:52:00 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -1368,8 +1368,14 @@ pgstat_bestart(void)
 	/*
 	 * To minimize the time spent modifying the entry, fetch all the
 	 * needed data first.
+	 *
+	 * If we have a MyProcPort, use its session start time (for consistency,
+	 * and to save a kernel call).
 	 */
-	proc_start_timestamp = GetCurrentTimestamp();
+	if (MyProcPort)
+		proc_start_timestamp = MyProcPort->SessionStartTime;
+	else
+		proc_start_timestamp = GetCurrentTimestamp();
 	userid = GetSessionUserId();
 
 	/*
@@ -1464,7 +1470,7 @@ pgstat_report_activity(const char *cmd_str)
 	 * To minimize the time spent modifying the entry, fetch all the
 	 * needed data first.
 	 */
-	start_timestamp = GetCurrentTimestamp();
+	start_timestamp = GetCurrentStatementStartTimestamp();
 
 	len = strlen(cmd_str);
 	len = pg_mbcliplen(cmd_str, len, PGBE_ACTIVITY_SIZE - 1);
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index aac116b466a..8164d7e5b03 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.487 2006/06/19 01:51:21 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.488 2006/06/20 22:52:00 tgl Exp $
  *
  * NOTES
  *
@@ -99,7 +99,6 @@
 #include "commands/async.h"
 #include "lib/dllist.h"
 #include "libpq/auth.h"
-#include "libpq/crypt.h"
 #include "libpq/libpq.h"
 #include "libpq/pqcomm.h"
 #include "libpq/pqsignal.h"
@@ -2609,8 +2608,9 @@ BackendInitialize(Port *port)
 
 	ClientAuthInProgress = true;	/* limit visibility of log messages */
 
-	/* save start time for end of session reporting */
-	gettimeofday(&(port->session_start), NULL);
+	/* save process start time */
+	port->SessionStartTime = GetCurrentTimestamp();
+	port->session_start = timestamptz_to_time_t(port->SessionStartTime);
 
 	/* set these to empty in case they are needed before we set them up */
 	port->remote_host = "";
@@ -2749,6 +2749,8 @@ BackendRun(Port *port)
 	char	  **av;
 	int			maxac;
 	int			ac;
+	long		secs;
+	int			usecs;
 	char		protobuf[32];
 	int			i;
 
@@ -2758,7 +2760,9 @@ BackendRun(Port *port)
 	 * a new random sequence in the random() library function.
 	 */
 	random_seed = 0;
-	srandom((unsigned int) (MyProcPid ^ port->session_start.tv_usec));
+	/* slightly hacky way to get integer microseconds part of timestamptz */
+	TimestampDifference(0, port->SessionStartTime, &secs, &usecs);
+	srandom((unsigned int) (MyProcPid ^ usecs));
 
 	/* ----------------
 	 * Now, build the argv vector that will be given to PostgresMain.