Fix pgstat_report_waiting() to not dump core if called before

pgstat_bestart() has been called; else any lock-block occurring
during InitPostgres() is disastrous.  I believe this explains
recent wasp regression failure; at least it explains the crash I
got while trying to duplicate the problem.  I also made
pgstat_report_activity() safe against the same scenario, just
in case.  The report_waiting hazard was created by my patch of
19-Aug to include waiting status in pg_stat_activity.

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index a37d9fa349fd282bc253d0e9f3a2bb26bda84a18..715de0071c1abf612d0250d7085491476fe2b450 100644 (file)
--- 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 1.137 2006/08/19 01:36:24 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.138 2006/08/28 19:38:09 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -1384,7 +1384,7 @@ pgstat_bestart(void)
 static void
 pgstat_beshutdown_hook(int code, Datum arg)
 {
-   volatile PgBackendStatus *beentry;
+   volatile PgBackendStatus *beentry = MyBEEntry;
 
    pgstat_report_tabstat();
 
@@ -1393,7 +1393,6 @@ pgstat_beshutdown_hook(int code, Datum arg)
     * st_changecount before and after.  We use a volatile pointer here
     * to ensure the compiler doesn't try to get cute.
     */
-   beentry = MyBEEntry;
    beentry->st_changecount++;
 
    beentry->st_procpid = 0;    /* mark invalid */
@@ -1413,11 +1412,11 @@ pgstat_beshutdown_hook(int code, Datum arg)
 void
 pgstat_report_activity(const char *cmd_str)
 {
-   volatile PgBackendStatus *beentry;
+   volatile PgBackendStatus *beentry = MyBEEntry;
    TimestampTz start_timestamp;
    int         len;
 
-   if (!pgstat_collect_querystring)
+   if (!pgstat_collect_querystring || !beentry)
        return;
 
    /*
@@ -1434,7 +1433,6 @@ pgstat_report_activity(const char *cmd_str)
     * st_changecount before and after.  We use a volatile pointer here
     * to ensure the compiler doesn't try to get cute.
     */
-   beentry = MyBEEntry;
    beentry->st_changecount++;
 
    beentry->st_activity_start_timestamp = start_timestamp;
@@ -1450,14 +1448,17 @@ pgstat_report_activity(const char *cmd_str)
  * pgstat_report_waiting() -
  *
  * Called from lock manager to report beginning or end of a lock wait.
+ *
+ * NB: this *must* be able to survive being called before MyBEEntry has been
+ * initialized.
  * ----------
  */
 void
 pgstat_report_waiting(bool waiting)
 {
-   volatile PgBackendStatus *beentry;
+   volatile PgBackendStatus *beentry = MyBEEntry;
 
-   if (!pgstat_collect_querystring)
+   if (!pgstat_collect_querystring || !beentry)
        return;
 
    /*
@@ -1465,8 +1466,6 @@ pgstat_report_waiting(bool waiting)
     * may modify, there seems no need to bother with the st_changecount
     * protocol.  The update must appear atomic in any case.
     */
-   beentry = MyBEEntry;
-
    beentry->st_waiting = waiting;
 }