[PGPRO-3365] Add syncpoint_interval GUC

Cherry-picked from a0cae9aeb5a1952ec9bb85762a30baa60137931c

tags: multimaster

Author: danolivo

src/include/multimaster.h

@@ -36,7 +36,6 @@
 #define MULTIMASTER_ADMIN                "mtm_admin"
 #define MULTIMASTER_PRECOMMITTED         "precommitted"
 #define MULTIMASTER_PREABORTED           "preaborted"
-#define MULTIMASTER_SYNCPOINT_INTERVAL    10*1024*1024
 
 #define MTM_MAX_NODES 16
 

src/include/syncpoint.h

@@ -33,6 +33,10 @@ typedef struct
 	XLogRecPtr	origin_lsn;
 } FilterEntry;
 
+
+extern int MtmSyncpointInterval;
+
+
 extern void MaybeLogSyncpoint(void);
 extern void SyncpointRegister(int origin_node_id, XLogRecPtr origin_lsn,
 				  XLogRecPtr receiver_lsn);

src/multimaster.c

@@ -38,6 +38,7 @@
 #include "logger.h"
 #include "commit.h"
 #include "messaging.h"
+#include "syncpoint.h"
 
 #include "compat.h"
 
@@ -584,6 +585,21 @@ NULL);
 							 NULL
 		);
 
+	DefineCustomIntVariable(
+							"multimaster.syncpoint_interval",
+							"Size of generated WAL between syncpoints",
+							NULL,
+							&MtmSyncpointInterval,
+							10*1024, /* 10 MB */
+							0,
+							INT_MAX,
+							PGC_SIGHUP,
+							GUC_UNIT_KB,
+							NULL,
+							NULL,
+							NULL
+		);
+
 	/* MtmDeadlockDetectorInit(MTM_MAX_NODES); */
 
 	/*

src/syncpoint.c

@@ -46,6 +46,8 @@
 #include "syncpoint.h"
 #include "logger.h"
 
+int			MtmSyncpointInterval;  /* in kilobytes */
+
 /* XXX: change to some receiver-local structures */
 static int
 origin_id_to_node_id(RepOriginId origin_id, MtmConfig *mtm_cfg)
@@ -87,11 +89,11 @@ void
 MaybeLogSyncpoint(void)
 {
 	/* do unlocked check first */
-	if (GetInsertRecPtr() - Mtm->latestSyncpoint < MULTIMASTER_SYNCPOINT_INTERVAL)
+	if (GetInsertRecPtr() - Mtm->latestSyncpoint < MtmSyncpointInterval * 1024)
 		return;
 
 	LWLockAcquire(Mtm->syncpoint_lock, LW_EXCLUSIVE);
-	if (GetInsertRecPtr() - Mtm->latestSyncpoint >= MULTIMASTER_SYNCPOINT_INTERVAL)
+	if (GetInsertRecPtr() - Mtm->latestSyncpoint >= MtmSyncpointInterval * 1024)
 	{
 		XLogRecPtr syncpoint_lsn;