Fix failure of archive recovery with recovery_min_apply_delay enabled.

recovery_min_apply_delay parameter is intended for use with streaming
replication deployments. However, the document clearly explains that
the parameter will be honored in all cases if it's specified. So it should
take effect even if in archive recovery. But, previously, archive recovery
with recovery_min_apply_delay enabled always failed, and caused assertion
failure if --enable-caasert is enabled.

The cause of this problem is that; the ownership of recoveryWakeupLatch
that recovery_min_apply_delay uses was taken only when standby mode
is requested. So unowned latch could be used in archive recovery, and
which caused the failure.

This commit changes recovery code so that the ownership of
recoveryWakeupLatch is taken even in archive recovery. Which prevents
archive recovery with recovery_min_apply_delay from failing.

Back-patch to v9.4 where recovery_min_apply_delay was added.

Author: Fujii Masao
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/CAHGQGwEyD6HdZLfdWc+95g=VQFPR4zQL4n+yHxQgGEGjaSVheQ@mail.gmail.com

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 69d4e19554ce2bd3cfd6811ece74ffbe2506d551..6ce037bd83e84d59e02b28013d06104f09468897 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6458,7 +6458,7 @@ StartupXLOG(void)
         * Take ownership of the wakeup latch if we're going to sleep during
         * recovery.
         */
-       if (StandbyModeRequested)
+       if (ArchiveRecoveryRequested)
                OwnLatch(&XLogCtl->recoveryWakeupLatch);
 
        /* Set up XLOG reader facility */
@@ -7445,7 +7445,7 @@ StartupXLOG(void)
         * We don't need the latch anymore. It's not strictly necessary to disown
         * it, but let's do it for the sake of tidiness.
         */
-       if (StandbyModeRequested)
+       if (ArchiveRecoveryRequested)
                DisownLatch(&XLogCtl->recoveryWakeupLatch);
 
        /*
@@ -12006,6 +12006,12 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
                                         * hope...
                                         */
 
+                                       /*
+                                        * We should be able to move to XLOG_FROM_STREAM
+                                        * only in standby mode.
+                                        */
+                                       Assert(StandbyMode);
+
                                        /*
                                         * Before we leave XLOG_FROM_STREAM state, make sure that
                                         * walreceiver is not active, so that it won't overwrite
@@ -12117,6 +12123,12 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
                                {
                                        bool            havedata;
 
+                                       /*
+                                        * We should be able to move to XLOG_FROM_STREAM
+                                        * only in standby mode.
+                                        */
+                                       Assert(StandbyMode);
+
                                        /*
                                         * Check if WAL receiver is still active.
                                         */