From 4ae08cd5fd19d566538005c15e7bf992ebae4c72 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Fri, 26 Jun 2020 20:41:29 -0400
Subject: [PATCH] Persist slot invalidation correctly
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We failed to save slot to disk after invalidating it, so the state was
lost in case of server restart or crash. Fix by marking it dirty and
flushing.
Also, if the slot is known invalidated we don't need to reason about the
LSN at all -- it's known invalidated. Only test the LSN if the slot is
known not invalidated.
Author: Fujii Masao <masao.fujii@oss.nttdata.com>
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/17a69cfe-f1c1-a416-ee25-ae15427c69eb@oss.nttdata.com
---
src/backend/replication/slot.c | 9 +++++----
src/backend/replication/slotfuncs.c | 16 ++++++++--------
2 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index e8761f3a18..57bbb6288c 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -1157,6 +1157,7 @@ restart:
if (XLogRecPtrIsInvalid(restart_lsn) || restart_lsn >= oldestLSN)
continue;
LWLockRelease(ReplicationSlotControlLock);
+ CHECK_FOR_INTERRUPTS();
/* Get ready to sleep on the slot in case it is active */
ConditionVariablePrepareToSleep(&s->active_cv);
@@ -1214,10 +1215,7 @@ restart:
* already been dropped.
*/
if (wspid == -1)
- {
- CHECK_FOR_INTERRUPTS();
goto restart;
- }
ereport(LOG,
(errmsg("invalidating slot \"%s\" because its restart_lsn %X/%X exceeds max_slot_wal_keep_size",
@@ -1229,10 +1227,13 @@ restart:
s->data.invalidated_at = s->data.restart_lsn;
s->data.restart_lsn = InvalidXLogRecPtr;
SpinLockRelease(&s->mutex);
+
+ /* Make sure the invalidated state persists across server restart */
+ ReplicationSlotMarkDirty();
+ ReplicationSlotSave();
ReplicationSlotRelease();
/* if we did anything, start from scratch */
- CHECK_FOR_INTERRUPTS();
goto restart;
}
LWLockRelease(ReplicationSlotControlLock);
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index fca18ffae5..88033a79b2 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -283,7 +283,6 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
bool nulls[PG_GET_REPLICATION_SLOTS_COLS];
WALAvailability walstate;
XLogSegNo last_removed_seg;
- XLogRecPtr targetLSN;
int i;
if (!slot->in_use)
@@ -344,14 +343,15 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
nulls[i++] = true;
/*
- * Report availability from invalidated_at when the slot has been
- * invalidated; otherwise slots would appear as invalid without any
- * more clues as to what happened.
+ * If invalidated_at is valid and restart_lsn is invalid, we know for
+ * certain that the slot has been invalidated. Otherwise, test
+ * availability from restart_lsn.
*/
- targetLSN = XLogRecPtrIsInvalid(slot_contents.data.restart_lsn) ?
- slot_contents.data.invalidated_at :
- slot_contents.data.restart_lsn;
- walstate = GetWALAvailability(targetLSN);
+ if (XLogRecPtrIsInvalid(slot_contents.data.restart_lsn) &&
+ !XLogRecPtrIsInvalid(slot_contents.data.invalidated_at))
+ walstate = WALAVAIL_REMOVED;
+ else
+ walstate = GetWALAvailability(slot_contents.data.restart_lsn);
switch (walstate)
{