From 0b9d3d4dcd0561fbf674e09af1160f087eda535b Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 4 Aug 2007 03:15:49 +0000
Subject: [PATCH] Fix a problem in my recent patch to initialize cancel_key for
autovac workers as well as regular backends: if no regular backend launches
before the autovac launcher tries to start an autovac worker, the postmaster
would get an Assert fault due to calling PostmasterRandom before random_seed
was initialized. Cleanest solution seems to be to take the initialization of
random_seed out of ServerLoop and let PostmasterRandom do it for itself.
---
src/backend/postmaster/postmaster.c | 53 ++++++++++++++---------------
1 file changed, 26 insertions(+), 27 deletions(-)
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 74d90e6f887..4543c5c5032 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 1.538 2007/08/03 20:06:50 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.539 2007/08/04 03:15:49 tgl Exp $
*
* NOTES
*
@@ -230,6 +230,7 @@ static volatile sig_atomic_t start_autovac_launcher = false;
* backend from the postmaster to that backend (via fork).
*/
static unsigned int random_seed = 0;
+static struct timeval random_start_time;
extern char *optarg;
extern int optind,
@@ -966,6 +967,8 @@ PostmasterMain(int argc, char *argv[])
* Remember postmaster startup time
*/
PgStartTime = GetCurrentTimestamp();
+ /* PostmasterRandom wants its own copy */
+ gettimeofday(&random_start_time, NULL);
/*
* We're ready to rock and roll...
@@ -1140,10 +1143,7 @@ ServerLoop(void)
int nSockets;
time_t now,
last_touch_time;
- struct timeval earlier,
- later;
- gettimeofday(&earlier, NULL);
last_touch_time = time(NULL);
nSockets = initMasks(&readmask);
@@ -1194,24 +1194,6 @@ ServerLoop(void)
*/
if (selres > 0)
{
- /*
- * Select a random seed at the time of first receiving a request.
- */
- while (random_seed == 0)
- {
- gettimeofday(&later, NULL);
-
- /*
- * We are not sure how much precision is in tv_usec, so we
- * swap the high and low 16 bits of 'later' and XOR them with
- * 'earlier'. On the off chance that the result is 0, we loop
- * until it isn't.
- */
- random_seed = earlier.tv_usec ^
- ((later.tv_usec << 16) |
- ((later.tv_usec >> 16) & 0xffff));
- }
-
for (i = 0; i < MAXLISTEN; i++)
{
if (ListenSocket[i] == -1)
@@ -2970,6 +2952,7 @@ BackendRun(Port *port)
* a new random sequence in the random() library function.
*/
random_seed = 0;
+ random_start_time.tv_usec = 0;
/* slightly hacky way to get integer microseconds part of timestamptz */
TimestampDifference(0, port->SessionStartTime, &secs, &usecs);
srandom((unsigned int) (MyProcPid ^ usecs));
@@ -3778,13 +3761,29 @@ RandomSalt(char *cryptSalt, char *md5Salt)
static long
PostmasterRandom(void)
{
- static bool initialized = false;
-
- if (!initialized)
+ /*
+ * Select a random seed at the time of first receiving a request.
+ */
+ if (random_seed == 0)
{
- Assert(random_seed != 0);
+ do
+ {
+ struct timeval random_stop_time;
+
+ gettimeofday(&random_stop_time, NULL);
+ /*
+ * We are not sure how much precision is in tv_usec, so we swap
+ * the high and low 16 bits of 'random_stop_time' and XOR them
+ * with 'random_start_time'. On the off chance that the result is
+ * 0, we loop until it isn't.
+ */
+ random_seed = random_start_time.tv_usec ^
+ ((random_stop_time.tv_usec << 16) |
+ ((random_stop_time.tv_usec >> 16) & 0xffff));
+ }
+ while (random_seed == 0);
+
srandom(random_seed);
- initialized = true;
}
return random();
--
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