Refactor some repetitive SLRU code

Functions to bootstrap and zero pages in various SLRU callers were
fairly duplicative.  We can slash almost two hundred lines with a couple
of simple helpers:

 - SimpleLruZeroAndWritePage: Does the equivalent of SimpleLruZeroPage
   followed by flushing the page to disk
 - XLogSimpleInsertInt64: Does a XLogBeginInsert followed by XLogInsert
   of a trivial record whose data is just an int64.

Author: Evgeny Voropaev <[email protected]>
Reviewed by: Álvaro Herrera <[email protected]>
Reviewed by: Andrey Borodin <[email protected]>
Reviewed by: Aleksander Alekseev <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/97820ce8-a1cd-407f-a02b-47368fadb14b%40tantorlabs.com

8 files changed, 71 insertions, 255 deletions

diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index 48f10bec91e..e80fbe109cf 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -110,9 +110,7 @@ static SlruCtlData XactCtlData;
 #define XactCtl (&XactCtlData)
 
 
-static int	ZeroCLOGPage(int64 pageno, bool writeXlog);
 static bool CLOGPagePrecedes(int64 page1, int64 page2);
-static void WriteZeroPageXlogRec(int64 pageno);
 static void WriteTruncateXlogRec(int64 pageno, TransactionId oldestXact,
 								 Oid oldestXactDb);
 static void TransactionIdSetPageStatus(TransactionId xid, int nsubxids,
@@ -832,41 +830,8 @@ check_transaction_buffers(int *newval, void **extra, GucSource source)
 void
 BootStrapCLOG(void)
 {
-	int			slotno;
-	LWLock	   *lock = SimpleLruGetBankLock(XactCtl, 0);
-
-	LWLockAcquire(lock, LW_EXCLUSIVE);
-
-	/* Create and zero the first page of the commit log */
-	slotno = ZeroCLOGPage(0, false);
-
-	/* Make sure it's written out */
-	SimpleLruWritePage(XactCtl, slotno);
-	Assert(!XactCtl->shared->page_dirty[slotno]);
-
-	LWLockRelease(lock);
-}
-
-/*
- * Initialize (or reinitialize) a page of CLOG to zeroes.
- * If writeXlog is true, also emit an XLOG record saying we did this.
- *
- * The page is not actually written, just set up in shared memory.
- * The slot number of the new page is returned.
- *
- * Control lock must be held at entry, and will be held at exit.
- */
-static int
-ZeroCLOGPage(int64 pageno, bool writeXlog)
-{
-	int			slotno;
-
-	slotno = SimpleLruZeroPage(XactCtl, pageno);
-
-	if (writeXlog)
-		WriteZeroPageXlogRec(pageno);
-
-	return slotno;
+	/* Zero the initial page and flush it to disk */
+	SimpleLruZeroAndWritePage(XactCtl, 0);
 }
 
 /*
@@ -974,8 +939,9 @@ ExtendCLOG(TransactionId newestXact)
 
 	LWLockAcquire(lock, LW_EXCLUSIVE);
 
-	/* Zero the page and make an XLOG entry about it */
-	ZeroCLOGPage(pageno, true);
+	/* Zero the page and make a WAL entry about it */
+	SimpleLruZeroPage(XactCtl, pageno);
+	XLogSimpleInsertInt64(RM_CLOG_ID, CLOG_ZEROPAGE, pageno);
 
 	LWLockRelease(lock);
 }
@@ -1068,17 +1034,6 @@ CLOGPagePrecedes(int64 page1, int64 page2)
 
 
 /*
- * Write a ZEROPAGE xlog record
- */
-static void
-WriteZeroPageXlogRec(int64 pageno)
-{
-	XLogBeginInsert();
-	XLogRegisterData(&pageno, sizeof(pageno));
-	(void) XLogInsert(RM_CLOG_ID, CLOG_ZEROPAGE);
-}
-
-/*
  * Write a TRUNCATE xlog record
  *
  * We must flush the xlog record to disk before returning --- see notes
@@ -1114,19 +1069,9 @@ clog_redo(XLogReaderState *record)
 	if (info == CLOG_ZEROPAGE)
 	{
 		int64		pageno;
-		int			slotno;
-		LWLock	   *lock;
 
 		memcpy(&pageno, XLogRecGetData(record), sizeof(pageno));
-
-		lock = SimpleLruGetBankLock(XactCtl, pageno);
-		LWLockAcquire(lock, LW_EXCLUSIVE);
-
-		slotno = ZeroCLOGPage(pageno, false);
-		SimpleLruWritePage(XactCtl, slotno);
-		Assert(!XactCtl->shared->page_dirty[slotno]);
-
-		LWLockRelease(lock);
+		SimpleLruZeroAndWritePage(XactCtl, pageno);
 	}
 	else if (info == CLOG_TRUNCATE)
 	{
diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.c
index 225ff7ca9f2..370b38e048b 100644
--- a/src/backend/access/transam/commit_ts.c
+++ b/src/backend/access/transam/commit_ts.c
@@ -114,11 +114,9 @@ static void SetXidCommitTsInPage(TransactionId xid, int nsubxids,
 static void TransactionIdSetCommitTs(TransactionId xid, TimestampTz ts,
 									 RepOriginId nodeid, int slotno);
 static void error_commit_ts_disabled(void);
-static int	ZeroCommitTsPage(int64 pageno, bool writeXlog);
 static bool CommitTsPagePrecedes(int64 page1, int64 page2);
 static void ActivateCommitTs(void);
 static void DeactivateCommitTs(void);
-static void WriteZeroPageXlogRec(int64 pageno);
 static void WriteTruncateXlogRec(int64 pageno, TransactionId oldestXid);
 
 /*
@@ -603,28 +601,6 @@ BootStrapCommitTs(void)
 }
 
 /*
- * Initialize (or reinitialize) a page of CommitTs to zeroes.
- * If writeXlog is true, also emit an XLOG record saying we did this.
- *
- * The page is not actually written, just set up in shared memory.
- * The slot number of the new page is returned.
- *
- * Control lock must be held at entry, and will be held at exit.
- */
-static int
-ZeroCommitTsPage(int64 pageno, bool writeXlog)
-{
-	int			slotno;
-
-	slotno = SimpleLruZeroPage(CommitTsCtl, pageno);
-
-	if (writeXlog)
-		WriteZeroPageXlogRec(pageno);
-
-	return slotno;
-}
-
-/*
  * This must be called ONCE during postmaster or standalone-backend startup,
  * after StartupXLOG has initialized TransamVariables->nextXid.
  */
@@ -754,16 +730,7 @@ ActivateCommitTs(void)
 
 	/* Create the current segment file, if necessary */
 	if (!SimpleLruDoesPhysicalPageExist(CommitTsCtl, pageno))
-	{
-		LWLock	   *lock = SimpleLruGetBankLock(CommitTsCtl, pageno);
-		int			slotno;
-
-		LWLockAcquire(lock, LW_EXCLUSIVE);
-		slotno = ZeroCommitTsPage(pageno, false);
-		SimpleLruWritePage(CommitTsCtl, slotno);
-		Assert(!CommitTsCtl->shared->page_dirty[slotno]);
-		LWLockRelease(lock);
-	}
+		SimpleLruZeroAndWritePage(CommitTsCtl, pageno);
 
 	/* Change the activation status in shared memory. */
 	LWLockAcquire(CommitTsLock, LW_EXCLUSIVE);
@@ -874,8 +841,12 @@ ExtendCommitTs(TransactionId newestXact)
 
 	LWLockAcquire(lock, LW_EXCLUSIVE);
 
-	/* Zero the page and make an XLOG entry about it */
-	ZeroCommitTsPage(pageno, !InRecovery);
+	/* Zero the page ... */
+	SimpleLruZeroPage(CommitTsCtl, pageno);
+
+	/* and make a WAL entry about that, unless we're in REDO */
+	if (!InRecovery)
+		XLogSimpleInsertInt64(RM_COMMIT_TS_ID, COMMIT_TS_ZEROPAGE, pageno);
 
 	LWLockRelease(lock);
 }
@@ -990,17 +961,6 @@ CommitTsPagePrecedes(int64 page1, int64 page2)
 
 
 /*
- * Write a ZEROPAGE xlog record
- */
-static void
-WriteZeroPageXlogRec(int64 pageno)
-{
-	XLogBeginInsert();
-	XLogRegisterData(&pageno, sizeof(pageno));
-	(void) XLogInsert(RM_COMMIT_TS_ID, COMMIT_TS_ZEROPAGE);
-}
-
-/*
  * Write a TRUNCATE xlog record
  */
 static void
@@ -1030,19 +990,9 @@ commit_ts_redo(XLogReaderState *record)
 	if (info == COMMIT_TS_ZEROPAGE)
 	{
 		int64		pageno;
-		int			slotno;
-		LWLock	   *lock;
 
 		memcpy(&pageno, XLogRecGetData(record), sizeof(pageno));
-
-		lock = SimpleLruGetBankLock(CommitTsCtl, pageno);
-		LWLockAcquire(lock, LW_EXCLUSIVE);
-
-		slotno = ZeroCommitTsPage(pageno, false);
-		SimpleLruWritePage(CommitTsCtl, slotno);
-		Assert(!CommitTsCtl->shared->page_dirty[slotno]);
-
-		LWLockRelease(lock);
+		SimpleLruZeroAndWritePage(CommitTsCtl, pageno);
 	}
 	else if (info == COMMIT_TS_TRUNCATE)
 	{
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 7a7afe3edc6..3cb09c3d598 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -401,8 +401,6 @@ static void mXactCachePut(MultiXactId multi, int nmembers,
 static char *mxstatus_to_string(MultiXactStatus status);
 
 /* management of SLRU infrastructure */
-static int	ZeroMultiXactOffsetPage(int64 pageno, bool writeXlog);
-static int	ZeroMultiXactMemberPage(int64 pageno, bool writeXlog);
 static bool MultiXactOffsetPagePrecedes(int64 page1, int64 page2);
 static bool MultiXactMemberPagePrecedes(int64 page1, int64 page2);
 static bool MultiXactOffsetPrecedes(MultiXactOffset offset1,
@@ -413,7 +411,6 @@ static bool MultiXactOffsetWouldWrap(MultiXactOffset boundary,
 									 MultiXactOffset start, uint32 distance);
 static bool SetOffsetVacuumLimit(bool is_startup);
 static bool find_multixact_start(MultiXactId multi, MultiXactOffset *result);
-static void WriteMZeroPageXlogRec(int64 pageno, uint8 info);
 static void WriteMTruncateXlogRec(Oid oldestMultiDB,
 								  MultiXactId startTruncOff,
 								  MultiXactId endTruncOff,
@@ -2033,70 +2030,9 @@ check_multixact_member_buffers(int *newval, void **extra, GucSource source)
 void
 BootStrapMultiXact(void)
 {
-	int			slotno;
-	LWLock	   *lock;
-
-	lock = SimpleLruGetBankLock(MultiXactOffsetCtl, 0);
-	LWLockAcquire(lock, LW_EXCLUSIVE);
-
-	/* Create and zero the first page of the offsets log */
-	slotno = ZeroMultiXactOffsetPage(0, false);
-
-	/* Make sure it's written out */
-	SimpleLruWritePage(MultiXactOffsetCtl, slotno);
-	Assert(!MultiXactOffsetCtl->shared->page_dirty[slotno]);
-
-	LWLockRelease(lock);
-
-	lock = SimpleLruGetBankLock(MultiXactMemberCtl, 0);
-	LWLockAcquire(lock, LW_EXCLUSIVE);
-
-	/* Create and zero the first page of the members log */
-	slotno = ZeroMultiXactMemberPage(0, false);
-
-	/* Make sure it's written out */
-	SimpleLruWritePage(MultiXactMemberCtl, slotno);
-	Assert(!MultiXactMemberCtl->shared->page_dirty[slotno]);
-
-	LWLockRelease(lock);
-}
-
-/*
- * Initialize (or reinitialize) a page of MultiXactOffset to zeroes.
- * If writeXlog is true, also emit an XLOG record saying we did this.
- *
- * The page is not actually written, just set up in shared memory.
- * The slot number of the new page is returned.
- *
- * Control lock must be held at entry, and will be held at exit.
- */
-static int
-ZeroMultiXactOffsetPage(int64 pageno, bool writeXlog)
-{
-	int			slotno;
-
-	slotno = SimpleLruZeroPage(MultiXactOffsetCtl, pageno);
-
-	if (writeXlog)
-		WriteMZeroPageXlogRec(pageno, XLOG_MULTIXACT_ZERO_OFF_PAGE);
-
-	return slotno;
-}
-
-/*
- * Ditto, for MultiXactMember
- */
-static int
-ZeroMultiXactMemberPage(int64 pageno, bool writeXlog)
-{
-	int			slotno;
-
-	slotno = SimpleLruZeroPage(MultiXactMemberCtl, pageno);
-
-	if (writeXlog)
-		WriteMZeroPageXlogRec(pageno, XLOG_MULTIXACT_ZERO_MEM_PAGE);
-
-	return slotno;
+	/* Zero the initial pages and flush them to disk */
+	SimpleLruZeroAndWritePage(MultiXactOffsetCtl, 0);
+	SimpleLruZeroAndWritePage(MultiXactMemberCtl, 0);
 }
 
 /*
@@ -2134,7 +2070,7 @@ MaybeExtendOffsetSlru(void)
 		 * with creating a new segment file even if the page we're writing is
 		 * not the first in it, so this is enough.
 		 */
-		slotno = ZeroMultiXactOffsetPage(pageno, false);
+		slotno = SimpleLruZeroPage(MultiXactOffsetCtl, pageno);
 		SimpleLruWritePage(MultiXactOffsetCtl, slotno);
 	}
 
@@ -2568,8 +2504,10 @@ ExtendMultiXactOffset(MultiXactId multi)
 
 	LWLockAcquire(lock, LW_EXCLUSIVE);
 
-	/* Zero the page and make an XLOG entry about it */
-	ZeroMultiXactOffsetPage(pageno, true);
+	/* Zero the page and make a WAL entry about it */
+	SimpleLruZeroPage(MultiXactOffsetCtl, pageno);
+	XLogSimpleInsertInt64(RM_MULTIXACT_ID, XLOG_MULTIXACT_ZERO_OFF_PAGE,
+						  pageno);
 
 	LWLockRelease(lock);
 }
@@ -2611,8 +2549,10 @@ ExtendMultiXactMember(MultiXactOffset offset, int nmembers)
 
 			LWLockAcquire(lock, LW_EXCLUSIVE);
 
-			/* Zero the page and make an XLOG entry about it */
-			ZeroMultiXactMemberPage(pageno, true);
+			/* Zero the page and make a WAL entry about it */
+			SimpleLruZeroPage(MultiXactMemberCtl, pageno);
+			XLogSimpleInsertInt64(RM_MULTIXACT_ID,
+								  XLOG_MULTIXACT_ZERO_MEM_PAGE, pageno);
 
 			LWLockRelease(lock);
 		}
@@ -3348,18 +3288,6 @@ MultiXactOffsetPrecedes(MultiXactOffset offset1, MultiXactOffset offset2)
 }
 
 /*
- * Write an xlog record reflecting the zeroing of either a MEMBERs or
- * OFFSETs page (info shows which)
- */
-static void
-WriteMZeroPageXlogRec(int64 pageno, uint8 info)
-{
-	XLogBeginInsert();
-	XLogRegisterData(&pageno, sizeof(pageno));
-	(void) XLogInsert(RM_MULTIXACT_ID, info);
-}
-
-/*
  * Write a TRUNCATE xlog record
  *
  * We must flush the xlog record to disk before returning --- see notes in
@@ -3401,36 +3329,16 @@ multixact_redo(XLogReaderState *record)
 	if (info == XLOG_MULTIXACT_ZERO_OFF_PAGE)
 	{
 		int64		pageno;
-		int			slotno;
-		LWLock	   *lock;
 
 		memcpy(&pageno, XLogRecGetData(record), sizeof(pageno));
-
-		lock = SimpleLruGetBankLock(MultiXactOffsetCtl, pageno);
-		LWLockAcquire(lock, LW_EXCLUSIVE);
-
-		slotno = ZeroMultiXactOffsetPage(pageno, false);
-		SimpleLruWritePage(MultiXactOffsetCtl, slotno);
-		Assert(!MultiXactOffsetCtl->shared->page_dirty[slotno]);
-
-		LWLockRelease(lock);
+		SimpleLruZeroAndWritePage(MultiXactOffsetCtl, pageno);
 	}
 	else if (info == XLOG_MULTIXACT_ZERO_MEM_PAGE)
 	{
 		int64		pageno;
-		int			slotno;
-		LWLock	   *lock;
 
 		memcpy(&pageno, XLogRecGetData(record), sizeof(pageno));
-
-		lock = SimpleLruGetBankLock(MultiXactMemberCtl, pageno);
-		LWLockAcquire(lock, LW_EXCLUSIVE);
-
-		slotno = ZeroMultiXactMemberPage(pageno, false);
-		SimpleLruWritePage(MultiXactMemberCtl, slotno);
-		Assert(!MultiXactMemberCtl->shared->page_dirty[slotno]);
-
-		LWLockRelease(lock);
+		SimpleLruZeroAndWritePage(MultiXactMemberCtl, pageno);
 	}
 	else if (info == XLOG_MULTIXACT_CREATE_ID)
 	{
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index fe56286d9a9..10ec259f382 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -434,6 +434,31 @@ SimpleLruZeroLSNs(SlruCtl ctl, int slotno)
 }
 
 /*
+ * This is a convenience wrapper for the common case of zeroing a page and
+ * immediately flushing it to disk.
+ *
+ * Control lock is acquired and released here.
+ */
+void
+SimpleLruZeroAndWritePage(SlruCtl ctl, int64 pageno)
+{
+	int			slotno;
+	LWLock	   *lock;
+
+	lock = SimpleLruGetBankLock(ctl, pageno);
+	LWLockAcquire(lock, LW_EXCLUSIVE);
+
+	/* Create and zero the page */
+	slotno = SimpleLruZeroPage(ctl, pageno);
+
+	/* Make sure it's written out */
+	SimpleLruWritePage(ctl, slotno);
+	Assert(!ctl->shared->page_dirty[slotno]);
+
+	LWLockRelease(lock);
+}
+
+/*
  * Wait for any active I/O on a page slot to finish.  (This does not
  * guarantee that new I/O hasn't been started before we return, though.
  * In fact the slot might not even contain the same page anymore.)
diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c
index 15153618fad..09aace9e09f 100644
--- a/src/backend/access/transam/subtrans.c
+++ b/src/backend/access/transam/subtrans.c
@@ -74,7 +74,6 @@ static SlruCtlData SubTransCtlData;
 #define SubTransCtl  (&SubTransCtlData)
 
 
-static int	ZeroSUBTRANSPage(int64 pageno);
 static bool SubTransPagePrecedes(int64 page1, int64 page2);
 
 
@@ -269,33 +268,8 @@ check_subtrans_buffers(int *newval, void **extra, GucSource source)
 void
 BootStrapSUBTRANS(void)
 {
-	int			slotno;
-	LWLock	   *lock = SimpleLruGetBankLock(SubTransCtl, 0);
-
-	LWLockAcquire(lock, LW_EXCLUSIVE);
-
-	/* Create and zero the first page of the subtrans log */
-	slotno = ZeroSUBTRANSPage(0);
-
-	/* Make sure it's written out */
-	SimpleLruWritePage(SubTransCtl, slotno);
-	Assert(!SubTransCtl->shared->page_dirty[slotno]);
-
-	LWLockRelease(lock);
-}
-
-/*
- * Initialize (or reinitialize) a page of SUBTRANS to zeroes.
- *
- * The page is not actually written, just set up in shared memory.
- * The slot number of the new page is returned.
- *
- * Control lock must be held at entry, and will be held at exit.
- */
-static int
-ZeroSUBTRANSPage(int64 pageno)
-{
-	return SimpleLruZeroPage(SubTransCtl, pageno);
+	/* Zero the initial page and flush it to disk */
+	SimpleLruZeroAndWritePage(SubTransCtl, 0);
 }
 
 /*
@@ -335,7 +309,7 @@ StartupSUBTRANS(TransactionId oldestActiveXID)
 			prevlock = lock;
 		}
 
-		(void) ZeroSUBTRANSPage(startPage);
+		(void) SimpleLruZeroPage(SubTransCtl, startPage);
 		if (startPage == endPage)
 			break;
 
@@ -395,7 +369,7 @@ ExtendSUBTRANS(TransactionId newestXact)
 	LWLockAcquire(lock, LW_EXCLUSIVE);
 
 	/* Zero the page */
-	ZeroSUBTRANSPage(pageno);
+	SimpleLruZeroPage(SubTransCtl, pageno);
 
 	LWLockRelease(lock);
 }
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
index 5ee9d0b028e..c7571429e8e 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -530,6 +530,18 @@ XLogInsert(RmgrId rmid, uint8 info)
 }
 
 /*
+ * Simple wrapper to XLogInsert to insert a WAL record with elementary
+ * contents (only an int64 is supported as value currently).
+ */
+XLogRecPtr
+XLogSimpleInsertInt64(RmgrId rmid, uint8 info, int64 value)
+{
+	XLogBeginInsert();
+	XLogRegisterData(&value, sizeof(value));
+	return XLogInsert(rmid, info);
+}
+
+/*
  * Assemble a WAL record from the registered data and buffers into an
  * XLogRecData chain, ready for insertion with XLogInsertRecord().
  *
diff --git a/src/include/access/slru.h b/src/include/access/slru.h
index e142800aab2..20dbd1e0070 100644
--- a/src/include/access/slru.h
+++ b/src/include/access/slru.h
@@ -187,6 +187,7 @@ extern void SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
 						  int bank_tranche_id, SyncRequestHandler sync_handler,
 						  bool long_segment_names);
 extern int	SimpleLruZeroPage(SlruCtl ctl, int64 pageno);
+extern void SimpleLruZeroAndWritePage(SlruCtl ctl, int64 pageno);
 extern int	SimpleLruReadPage(SlruCtl ctl, int64 pageno, bool write_ok,
 							  TransactionId xid);
 extern int	SimpleLruReadPage_ReadOnly(SlruCtl ctl, int64 pageno,
diff --git a/src/include/access/xloginsert.h b/src/include/access/xloginsert.h
index cf057f033a2..d6a71415d4f 100644
--- a/src/include/access/xloginsert.h
+++ b/src/include/access/xloginsert.h
@@ -44,6 +44,7 @@
 extern void XLogBeginInsert(void);
 extern void XLogSetRecordFlags(uint8 flags);
 extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info);
+extern XLogRecPtr XLogSimpleInsertInt64(RmgrId rmid, uint8 info, int64 value);
 extern void XLogEnsureRecordSpace(int max_block_id, int ndatas);
 extern void XLogRegisterData(const void *data, uint32 len);
 extern void XLogRegisterBuffer(uint8 block_id, Buffer buffer, uint8 flags);