Avoid unnecessary public struct declaration in slru.h

Instead, declare a public wrapper of the sole function using it for
external callers, so that they don't have to always pass a NULL
argument.

Author: Kevin Grittner

src/backend/access/transam/clog.c

@@ -445,7 +445,7 @@ BootStrapCLOG(void)
 	slotno = ZeroCLOGPage(0, false);
 
 	/* Make sure it's written out */
-	SimpleLruWritePage(ClogCtl, slotno, NULL);
+	SimpleLruWritePage(ClogCtl, slotno);
 	Assert(!ClogCtl->shared->page_dirty[slotno]);
 
 	LWLockRelease(CLogControlLock);
@@ -698,7 +698,7 @@ clog_redo(XLogRecPtr lsn, XLogRecord *record)
 		LWLockAcquire(CLogControlLock, LW_EXCLUSIVE);
 
 		slotno = ZeroCLOGPage(pageno, false);
-		SimpleLruWritePage(ClogCtl, slotno, NULL);
+		SimpleLruWritePage(ClogCtl, slotno);
 		Assert(!ClogCtl->shared->page_dirty[slotno]);
 
 		LWLockRelease(CLogControlLock);

src/backend/access/transam/multixact.c

@@ -1454,7 +1454,7 @@ BootStrapMultiXact(void)
 	slotno = ZeroMultiXactOffsetPage(0, false);
 
 	/* Make sure it's written out */
-	SimpleLruWritePage(MultiXactOffsetCtl, slotno, NULL);
+	SimpleLruWritePage(MultiXactOffsetCtl, slotno);
 	Assert(!MultiXactOffsetCtl->shared->page_dirty[slotno]);
 
 	LWLockRelease(MultiXactOffsetControlLock);
@@ -1465,7 +1465,7 @@ BootStrapMultiXact(void)
 	slotno = ZeroMultiXactMemberPage(0, false);
 
 	/* Make sure it's written out */
-	SimpleLruWritePage(MultiXactMemberCtl, slotno, NULL);
+	SimpleLruWritePage(MultiXactMemberCtl, slotno);
 	Assert(!MultiXactMemberCtl->shared->page_dirty[slotno]);
 
 	LWLockRelease(MultiXactMemberControlLock);
@@ -1986,7 +1986,7 @@ multixact_redo(XLogRecPtr lsn, XLogRecord *record)
 		LWLockAcquire(MultiXactOffsetControlLock, LW_EXCLUSIVE);
 
 		slotno = ZeroMultiXactOffsetPage(pageno, false);
-		SimpleLruWritePage(MultiXactOffsetCtl, slotno, NULL);
+		SimpleLruWritePage(MultiXactOffsetCtl, slotno);
 		Assert(!MultiXactOffsetCtl->shared->page_dirty[slotno]);
 
 		LWLockRelease(MultiXactOffsetControlLock);
@@ -2001,7 +2001,7 @@ multixact_redo(XLogRecPtr lsn, XLogRecord *record)
 		LWLockAcquire(MultiXactMemberControlLock, LW_EXCLUSIVE);
 
 		slotno = ZeroMultiXactMemberPage(pageno, false);
-		SimpleLruWritePage(MultiXactMemberCtl, slotno, NULL);
+		SimpleLruWritePage(MultiXactMemberCtl, slotno);
 		Assert(!MultiXactMemberCtl->shared->page_dirty[slotno]);
 
 		LWLockRelease(MultiXactMemberControlLock);

src/backend/access/transam/slru.c

@@ -78,6 +78,8 @@ typedef struct SlruFlushData
 	int			segno[MAX_FLUSH_BUFFERS];		/* their log seg#s */
 } SlruFlushData;
 
+typedef struct SlruFlushData *SlruFlush;
+
 /*
  * Macro to mark a buffer slot "most recently used".  Note multiple evaluation
  * of arguments!
@@ -123,6 +125,7 @@ static int	slru_errno;
 
 static void SimpleLruZeroLSNs(SlruCtl ctl, int slotno);
 static void SimpleLruWaitIO(SlruCtl ctl, int slotno);
+static void SlruInternalWritePage(SlruCtl ctl, int slotno, SlruFlush fdata);
 static bool SlruPhysicalReadPage(SlruCtl ctl, int pageno, int slotno);
 static bool SlruPhysicalWritePage(SlruCtl ctl, int pageno, int slotno,
 					  SlruFlush fdata);
@@ -485,8 +488,8 @@ SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno, TransactionId xid)
  *
  * Control lock must be held at entry, and will be held at exit.
  */
-void
-SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
+static void
+SlruInternalWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
 {
 	SlruShared	shared = ctl->shared;
 	int			pageno = shared->page_number[slotno];
@@ -552,6 +555,17 @@ SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
 		SlruReportIOError(ctl, pageno, InvalidTransactionId);
 }
 
+/*
+ * Wrapper of SlruInternalWritePage, for external callers.
+ * fdata is always passed a NULL here.
+ */
+void
+SimpleLruWritePage(SlruCtl ctl, int slotno)
+{
+	SlruInternalWritePage(ctl, slotno, NULL);
+}
+
+
 /*
  * Physical read of a (previously existing) page into a buffer slot
  *
@@ -975,7 +989,7 @@ SlruSelectLRUPage(SlruCtl ctl, int pageno)
 		 * we wait for the existing I/O to complete.
 		 */
 		if (shared->page_status[bestslot] == SLRU_PAGE_VALID)
-			SimpleLruWritePage(ctl, bestslot, NULL);
+			SlruInternalWritePage(ctl, bestslot, NULL);
 		else
 			SimpleLruWaitIO(ctl, bestslot);
 
@@ -1009,7 +1023,7 @@ SimpleLruFlush(SlruCtl ctl, bool checkpoint)
 
 	for (slotno = 0; slotno < shared->num_slots; slotno++)
 	{
-		SimpleLruWritePage(ctl, slotno, &fdata);
+		SlruInternalWritePage(ctl, slotno, &fdata);
 
 		/*
 		 * When called during a checkpoint, we cannot assert that the slot is
@@ -1114,7 +1128,7 @@ restart:;
 		 * keep the logic the same as it was.)
 		 */
 		if (shared->page_status[slotno] == SLRU_PAGE_VALID)
-			SimpleLruWritePage(ctl, slotno, NULL);
+			SlruInternalWritePage(ctl, slotno, NULL);
 		else
 			SimpleLruWaitIO(ctl, slotno);
 		goto restart;

src/backend/access/transam/subtrans.c

@@ -205,7 +205,7 @@ BootStrapSUBTRANS(void)
 	slotno = ZeroSUBTRANSPage(0);
 
 	/* Make sure it's written out */
-	SimpleLruWritePage(SubTransCtl, slotno, NULL);
+	SimpleLruWritePage(SubTransCtl, slotno);
 	Assert(!SubTransCtl->shared->page_dirty[slotno]);
 
 	LWLockRelease(SubtransControlLock);

src/backend/commands/async.c

@@ -507,7 +507,7 @@ AsyncShmemInit(void)
 		LWLockAcquire(AsyncCtlLock, LW_EXCLUSIVE);
 		slotno = SimpleLruZeroPage(AsyncCtl, QUEUE_POS_PAGE(QUEUE_HEAD));
 		/* This write is just to verify that pg_notify/ is writable */
-		SimpleLruWritePage(AsyncCtl, slotno, NULL);
+		SimpleLruWritePage(AsyncCtl, slotno);
 		LWLockRelease(AsyncCtlLock);
 	}
 }

src/include/access/slru.h

@@ -133,9 +133,6 @@ typedef struct SlruCtlData
 
 typedef SlruCtlData *SlruCtl;
 
-/* Opaque struct known only in slru.c */
-typedef struct SlruFlushData *SlruFlush;
-
 
 extern Size SimpleLruShmemSize(int nslots, int nlsns);
 extern void SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
@@ -145,7 +142,7 @@ extern int SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok,
 				  TransactionId xid);
 extern int SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno,
 						   TransactionId xid);
-extern void SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata);
+extern void SimpleLruWritePage(SlruCtl ctl, int slotno);
 extern void SimpleLruFlush(SlruCtl ctl, bool checkpoint);
 extern void SimpleLruTruncate(SlruCtl ctl, int cutoffPage);
 extern bool SlruScanDirectory(SlruCtl ctl, int cutoffPage, bool doDeletions);