Fuse shared archive with ycmdb.shared_archive

Author: x4m

src/backend/access/transam/xlog.c

@@ -118,6 +118,7 @@ int			wal_keep_size_mb = 0;
 int			XLOGbuffers = -1;
 int			XLogArchiveTimeout = 0;
 int			XLogArchiveMode = ARCHIVE_MODE_OFF;
+bool		ycmdb_shared_archive = false;	/* makes archive_mode=on act as shared */
 char	   *XLogArchiveCommand = NULL;
 bool		EnableHotStandby = false;
 bool		fullPageWrites = true;

src/backend/postmaster/pgarch.c

@@ -388,7 +388,7 @@ pgarch_ArchiverCopyLoop(void)
 	 * marks files as .done when the primary confirms archival. After
 	 * promotion, the archiver starts working normally.
 	 */
-	if (XLogArchiveMode == ARCHIVE_MODE_SHARED && RecoveryInProgress())
+	if (EffectiveArchiveModeIsShared() && RecoveryInProgress())
 		return;
 
 	/* force directory scan in the first call to pgarch_readyXlog() */

src/backend/replication/walreceiver.c

@@ -1115,7 +1115,7 @@ XLogWalRcvClose(XLogRecPtr recptr, TimeLineID tli)
 	{
 		XLogArchiveNotify(xlogfname);
 	}
-	else if (XLogArchiveMode == ARCHIVE_MODE_SHARED)
+	else if (EffectiveArchiveModeIsShared())
 	{
 		/*
 		 * In shared mode, check if this segment is already archived on primary.

src/backend/replication/walsender.c

@@ -84,6 +84,7 @@
 #include "storage/ipc.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
+#include "storage/procarray.h"
 #include "tcop/dest.h"
 #include "tcop/tcopprot.h"
 #include "utils/acl.h"
@@ -2779,8 +2780,8 @@ WalSndArchivalReport(void)
 	TimestampTz now;
 	char	   *last_archived;
 
-	/* Only send reports when archive_mode=shared */
-	if (XLogArchiveMode != ARCHIVE_MODE_SHARED)
+	/* Only send reports when shared archive is active */
+	if (!EffectiveArchiveModeIsShared())
 		return;
 
 	/* Only send reports during physical streaming replication, not during backup */

src/backend/utils/misc/guc_tables.c

@@ -34,6 +34,7 @@
 #include "access/slru.h"
 #include "access/toast_compression.h"
 #include "access/twophase.h"
+#include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "access/xlogprefetcher.h"
 #include "access/xlogrecovery.h"
@@ -1226,6 +1227,17 @@ struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"ycmdb.shared_archive", PGC_POSTMASTER, WAL_ARCHIVING,
+			gettext_noop("Makes archive_mode=on behave as shared (for managed service compatibility)."),
+			gettext_noop("When true, archive_mode=on is treated as archive_mode=shared. Does not affect archive_mode=off or archive_mode=always. Used when control plane cannot configure archive_mode=shared directly."),
+			GUC_NOT_IN_SAMPLE
+		},
+		&ycmdb_shared_archive,
+		false,
+		NULL, NULL, NULL
+	},
+
 	{
 		{"wal_init_zero", PGC_SUSET, WAL_SETTINGS,
 			gettext_noop("Writes zeroes to new WAL files before first use."),

src/include/access/xlog.h

@@ -68,6 +68,15 @@ typedef enum ArchiveMode
 	ARCHIVE_MODE_SHARED,		/* shared archive between primary and standby */
 } ArchiveMode;
 extern PGDLLIMPORT int XLogArchiveMode;
+extern PGDLLIMPORT bool ycmdb_shared_archive;
+
+/*
+ * True when shared archive behavior is active: either archive_mode=shared
+ * or archive_mode=on with ycmdb.shared_archive=true (managed service).
+ */
+#define EffectiveArchiveModeIsShared() \
+	(XLogArchiveMode == ARCHIVE_MODE_SHARED || \
+	 (XLogArchiveMode == ARCHIVE_MODE_ON && ycmdb_shared_archive))
 
 /* WAL levels */
 typedef enum WalLevel