From 1bdae16fca884a9190dc330790e7a63c04989fa3 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Fri, 1 Jul 2016 13:53:46 -0400 Subject: [PATCH] walreceiver: tweak pg_stat_wal_receiver behavior MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit There are two problems in the original coding: one is that if one walreceiver process exits, the ready_to_display flag remains set in shared memory, exposing the conninfo of the next walreceiver before obfuscating. Fix by having WalRcvDie reset the flag. Second, the sleep-and-retry behavior that waited until walreceiver had set ready_to_display wasn't liked; the preference is to have it return no data instead, so let's do that. Bugs in 9ed551e0a reported by Fujii Masao and Michël Paquier. Author: Michaël Paquier --- src/backend/replication/walreceiver.c | 22 ++++++---------------- 1 file changed, 6 insertions(+), 16 deletions(-) diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c index d552f04901..413ee3a5c1 100644 --- a/src/backend/replication/walreceiver.c +++ b/src/backend/replication/walreceiver.c @@ -246,6 +246,7 @@ WalReceiverMain(void) walrcv->walRcvState = WALRCV_STREAMING; /* Fetch information required to start streaming */ + walrcv->ready_to_display = false; strlcpy(conninfo, (char *) walrcv->conninfo, MAXCONNINFO); strlcpy(slotname, (char *) walrcv->slotname, NAMEDATALEN); startpoint = walrcv->receiveStart; @@ -770,6 +771,7 @@ WalRcvDie(int code, Datum arg) Assert(walrcv->pid == MyProcPid); walrcv->walRcvState = WALRCV_STOPPED; walrcv->pid = 0; + walrcv->ready_to_display = false; SpinLockRelease(&walrcv->mutex); /* Terminate the connection gracefully. */ @@ -1343,24 +1345,12 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS) char *slotname; char *conninfo; - /* No WAL receiver, just return a tuple with NULL values */ - if (walrcv->pid == 0) - PG_RETURN_NULL(); - /* - * Users attempting to read this data mustn't be shown security sensitive - * data, so sleep until everything has been properly obfuscated. + * No WAL receiver (or not ready yet), just return a tuple with NULL + * values */ -retry: - SpinLockAcquire(&walrcv->mutex); - if (!walrcv->ready_to_display) - { - SpinLockRelease(&walrcv->mutex); - CHECK_FOR_INTERRUPTS(); - pg_usleep(1000); - goto retry; - } - SpinLockRelease(&walrcv->mutex); + if (walrcv->pid == 0 || !walrcv->ready_to_display) + PG_RETURN_NULL(); /* determine result type */ if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) -- 2.40.0