From 43a87d3267e89a0bc231373dc69aaa73398b9aca Mon Sep 17 00:00:00 2001
From: Artur Zakirov <zaartur@gmail.com>
Date: Tue, 4 Nov 2025 14:28:54 +0100
Subject: [PATCH] Add RecoveryStopsHook for extensions to handle custom WAL
 records

---
 src/backend/access/transam/xlogrecovery.c | 24 ++++++++++++++++++++++-
 src/include/access/xlogrecovery.h         | 10 ++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index 12bf6eb22c8..f38c48208a7 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -2567,8 +2567,28 @@ recoveryStopsBefore(XLogReaderState *record)
 		return true;
 	}
 
+	/* Check RecoveryStopsHook for custom records */
+	if (RmgrIdIsCustom(XLogRecGetRmid(record)) && (RecoveryStopsBeforeHook != NULL))
+	{
+		stopsHere = RecoveryStopsBeforeHook(record, &recordXid, &recordXtime);
+
+		if (stopsHere)
+		{
+			recoveryStopAfter = false;
+			recoveryStopXid = recordXid;
+			recoveryStopLSN = InvalidXLogRecPtr;
+			recoveryStopTime = recordXtime;
+			recoveryStopName[0] = '\0';
+
+			ereport(LOG,
+					(errmsg("recovery stopping by hook before transaction %u, time %s",
+							recoveryStopXid,
+							timestamptz_to_str(recoveryStopTime))));
+			return true;
+		}
+	}
 	/* Otherwise we only consider stopping before COMMIT or ABORT records. */
-	if (XLogRecGetRmid(record) != RM_XACT_ID)
+	else if (XLogRecGetRmid(record) != RM_XACT_ID)
 		return false;
 
 	xact_info = XLogRecGetInfo(record) & XLOG_XACT_OPMASK;
@@ -4506,6 +4526,8 @@ GetXLogReplayRecPtr(TimeLineID *replayTLI)
 
 GetReplayXlogPtrHookType GetReplayXlogPtrHook = NULL;
 
+RecoveryStopsBeforeHookType RecoveryStopsBeforeHook = NULL;
+
 /*
  * Get effective latest redo apply position.
  *
diff --git a/src/include/access/xlogrecovery.h b/src/include/access/xlogrecovery.h
index cec67fb9c89..8ab6e99f86d 100644
--- a/src/include/access/xlogrecovery.h
+++ b/src/include/access/xlogrecovery.h
@@ -50,6 +50,10 @@ typedef enum RecoveryPauseState
 
 typedef XLogRecPtr (*GetReplayXlogPtrHookType) (void);
 
+typedef bool (*RecoveryStopsBeforeHookType) (XLogReaderState *record,
+											 TransactionId *recordXid,
+											 TimestampTz *recordXtime);
+
 /* User-settable GUC parameters */
 extern PGDLLIMPORT bool recoveryTargetInclusive;
 extern PGDLLIMPORT int recoveryTargetAction;
@@ -81,6 +85,12 @@ extern PGDLLIMPORT bool StandbyMode;
 /* Hook for extensions to tune replay xlog pointer */
 extern PGDLLIMPORT GetReplayXlogPtrHookType GetReplayXlogPtrHook;
 
+/*
+ * Hook for extensions to be able to decides to stop applying the WAL files
+ * based on custom WAL records.
+ */
+extern PGDLLIMPORT RecoveryStopsBeforeHookType RecoveryStopsBeforeHook;
+
 extern Size XLogRecoveryShmemSize(void);
 extern void XLogRecoveryShmemInit(void);