Implement LockBufferForCleanup(), which will allow concurrent VACUUM

to wait until it's safe to remove tuples and compact free space in a
shared buffer page.  Miscellaneous small code cleanups in bufmgr, too.

src/backend/access/transam/xact.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.104 2001/06/22 19:16:21 wieck Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.105 2001/07/06 21:04:25 tgl Exp $
  *
  * NOTES
  *		Transaction aborts can now occur two ways:
@@ -653,7 +653,7 @@ void
 RecordTransactionCommit()
 {
 	TransactionId xid;
-	int			leak;
+	bool		leak;
 
 	xid = GetCurrentTransactionId();
 

src/backend/storage/buffer/README

+$Header: /cvsroot/pgsql/src/backend/storage/buffer/README,v 1.1 2001/07/06 21:04:25 tgl Exp $
+
+Notes about shared buffer access rules
+--------------------------------------
+
+There are two separate access control mechanisms for shared disk buffers:
+reference counts (a/k/a pin counts) and buffer locks.  (Actually, there's
+a third level of access control: one must hold the appropriate kind of
+lock on a relation before one can legally access any page belonging to
+the relation.  Relation-level locks are not discussed here.)
+
+Pins: one must "hold a pin on" a buffer (increment its reference count)
+before being allowed to do anything at all with it.  An unpinned buffer is
+subject to being reclaimed and reused for a different page at any instant,
+so touching it is unsafe.  Typically a pin is acquired via ReadBuffer and
+released via WriteBuffer (if one modified the page) or ReleaseBuffer (if not).
+It is OK and indeed common for a single backend to pin a page more than
+once concurrently; the buffer manager handles this efficiently.  It is
+considered OK to hold a pin for long intervals --- for example, sequential
+scans hold a pin on the current page until done processing all the tuples
+on the page, which could be quite a while if the scan is the outer scan of
+a join.  Similarly, btree index scans hold a pin on the current index page.
+This is OK because normal operations never wait for a page's pin count to
+drop to zero.  (Anything that might need to do such a wait is instead
+handled by waiting to obtain the relation-level lock, which is why you'd
+better hold one first.)  Pins may not be held across transaction
+boundaries, however.
+
+Buffer locks: there are two kinds of buffer locks, shared and exclusive,
+which act just as you'd expect: multiple backends can hold shared locks on
+the same buffer, but an exclusive lock prevents anyone else from holding
+either shared or exclusive lock.  (These can alternatively be called READ
+and WRITE locks.)  These locks are short-term: they should not be held for
+long.  They are implemented as per-buffer spinlocks, so another backend
+trying to acquire a competing lock will spin as long as you hold yours!
+Buffer locks are acquired and released by LockBuffer().  It will *not* work
+for a single backend to try to acquire multiple locks on the same buffer.
+One must pin a buffer before trying to lock it.
+
+Buffer access rules:
+
+1. To scan a page for tuples, one must hold a pin and either shared or
+exclusive lock.  To examine the commit status (XIDs and status bits) of
+a tuple in a shared buffer, one must likewise hold a pin and either shared
+or exclusive lock.
+
+2. Once one has determined that a tuple is interesting (visible to the
+current transaction) one may drop the buffer lock, yet continue to access
+the tuple's data for as long as one holds the buffer pin.  This is what is
+typically done by heap scans, since the tuple returned by heap_fetch
+contains a pointer to tuple data in the shared buffer.  Therefore the
+tuple cannot go away while the pin is held (see rule #5).  Its state could
+change, but that is assumed not to matter after the initial determination
+of visibility is made.
+
+3. To add a tuple or change the xmin/xmax fields of an existing tuple,
+one must hold a pin and an exclusive lock on the containing buffer.
+This ensures that no one else might see a partially-updated state of the
+tuple.
+
+4. It is considered OK to update tuple commit status bits (ie, OR the
+values HEAP_XMIN_COMMITTED, HEAP_XMIN_INVALID, HEAP_XMAX_COMMITTED, or
+HEAP_XMAX_INVALID into t_infomask) while holding only a shared lock and
+pin on a buffer.  This is OK because another backend looking at the tuple
+at about the same time would OR the same bits into the field, so there
+is little or no risk of conflicting update; what's more, if there did
+manage to be a conflict it would merely mean that one bit-update would
+be lost and need to be done again later.  These four bits are only hints
+(they cache the results of transaction status lookups in pg_log), so no
+great harm is done if they get reset to zero by conflicting updates.
+
+5. To physically remove a tuple or compact free space on a page, one
+must hold a pin and an exclusive lock, *and* observe while holding the
+exclusive lock that the buffer's shared reference count is one (ie,
+no other backend holds a pin).  If these conditions are met then no other
+backend can perform a page scan until the exclusive lock is dropped, and
+no other backend can be holding a reference to an existing tuple that it
+might expect to examine again.  Note that another backend might pin the
+buffer (increment the refcount) while one is performing the cleanup, but
+it won't be able to actually examine the page until it acquires shared
+or exclusive lock.
+
+
+As of 7.1, the only operation that removes tuples or compacts free space is
+(oldstyle) VACUUM.  It does not have to implement rule #5 directly, because
+it instead acquires exclusive lock at the relation level, which ensures
+indirectly that no one else is accessing pages of the relation at all.
+
+To implement concurrent VACUUM we will need to make it obey rule #5 fully.
+To do this, we'll create a new buffer manager operation
+LockBufferForCleanup() that gets an exclusive lock and then checks to see
+if the shared pin count is currently 1.  If not, it releases the exclusive
+lock (but not the caller's pin) and waits until signaled by another backend,
+whereupon it tries again.  The signal will occur when UnpinBuffer
+decrements the shared pin count to 1.  As indicated above, this operation
+might have to wait a good while before it acquires lock, but that shouldn't
+matter much for concurrent VACUUM.  The current implementation only
+supports a single waiter for pin-count-1 on any particular shared buffer.
+This is enough for VACUUM's use, since we don't allow multiple VACUUMs
+concurrently on a single relation anyway.

src/backend/storage/buffer/buf_init.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/buffer/buf_init.c,v 1.42 2001/03/22 03:59:44 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/buffer/buf_init.c,v 1.43 2001/07/06 21:04:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -63,7 +63,6 @@ long	   *PrivateRefCount;	/* also used in freelist.c */
 bits8	   *BufferLocks;		/* flag bits showing locks I have set */
 BufferTag  *BufferTagLastDirtied;		/* tag buffer had when last
 										 * dirtied by me */
-BufferBlindId *BufferBlindLastDirtied;
 bool	   *BufferDirtiedByMe;	/* T if buf has been dirtied in cur xact */
 
 
@@ -237,7 +236,6 @@ InitBufferPoolAccess(void)
 	PrivateRefCount = (long *) calloc(NBuffers, sizeof(long));
 	BufferLocks = (bits8 *) calloc(NBuffers, sizeof(bits8));
 	BufferTagLastDirtied = (BufferTag *) calloc(NBuffers, sizeof(BufferTag));
-	BufferBlindLastDirtied = (BufferBlindId *) calloc(NBuffers, sizeof(BufferBlindId));
 	BufferDirtiedByMe = (bool *) calloc(NBuffers, sizeof(bool));
 
 	/*

src/backend/storage/buffer/freelist.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/buffer/freelist.c,v 1.23 2001/01/24 19:43:06 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/buffer/freelist.c,v 1.24 2001/07/06 21:04:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,14 +29,14 @@
 
 #include "storage/buf_internals.h"
 #include "storage/bufmgr.h"
+#include "storage/proc.h"
 
 
 static BufferDesc *SharedFreeList;
 
-/* only actually used in debugging.  The lock
- * should be acquired before calling the freelist manager.
+/*
+ * State-checking macros
  */
-extern SPINLOCK BufMgrLock;
 
 #define IsInQueue(bf) \
 ( \
@@ -45,7 +45,7 @@ extern SPINLOCK BufMgrLock;
 	AssertMacro((bf->flags & BM_FREE)) \
 )
 
-#define NotInQueue(bf) \
+#define IsNotInQueue(bf) \
 ( \
 	AssertMacro((bf->freeNext == INVALID_DESCRIPTOR)), \
 	AssertMacro((bf->freePrev == INVALID_DESCRIPTOR)), \
@@ -61,14 +61,14 @@ extern SPINLOCK BufMgrLock;
  * the manner in which buffers are added to the freelist queue.
  * Currently, they are added on an LRU basis.
  */
-void
+static void
 AddBufferToFreelist(BufferDesc *bf)
 {
 #ifdef BMTRACE
 	_bm_trace(bf->tag.relId.dbId, bf->tag.relId.relId, bf->tag.blockNum,
 			  BufferDescriptorGetBuffer(bf), BMT_DEALLOC);
 #endif	 /* BMTRACE */
-	NotInQueue(bf);
+	IsNotInQueue(bf);
 
 	/* change bf so it points to inFrontOfNew and its successor */
 	bf->freePrev = SharedFreeList->freePrev;
@@ -83,13 +83,14 @@ AddBufferToFreelist(BufferDesc *bf)
 
 /*
  * PinBuffer -- make buffer unavailable for replacement.
+ *
+ * This should be applied only to shared buffers, never local ones.
+ * Bufmgr lock must be held by caller.
  */
 void
 PinBuffer(BufferDesc *buf)
 {
-	long		b;
-
-	/* Assert (buf->refcount < 25); */
+	int		b = BufferDescriptorGetBuffer(buf) - 1;
 
 	if (buf->refcount == 0)
 	{
@@ -104,13 +105,12 @@ PinBuffer(BufferDesc *buf)
 		buf->flags &= ~BM_FREE;
 	}
 	else
-		NotInQueue(buf);
+		IsNotInQueue(buf);
 
-	b = BufferDescriptorGetBuffer(buf) - 1;
-	Assert(PrivateRefCount[b] >= 0);
 	if (PrivateRefCount[b] == 0)
 		buf->refcount++;
 	PrivateRefCount[b]++;
+	Assert(PrivateRefCount[b] > 0);
 }
 
 #ifdef NOT_USED
@@ -135,24 +135,35 @@ refcount = %ld, file: %s, line: %d\n",
 
 /*
  * UnpinBuffer -- make buffer available for replacement.
+ *
+ * This should be applied only to shared buffers, never local ones.
+ * Bufmgr lock must be held by caller.
  */
 void
 UnpinBuffer(BufferDesc *buf)
 {
-	long		b = BufferDescriptorGetBuffer(buf) - 1;
+	int		b = BufferDescriptorGetBuffer(buf) - 1;
 
+	IsNotInQueue(buf);
 	Assert(buf->refcount > 0);
 	Assert(PrivateRefCount[b] > 0);
 	PrivateRefCount[b]--;
 	if (PrivateRefCount[b] == 0)
 		buf->refcount--;
-	NotInQueue(buf);
 
 	if (buf->refcount == 0)
 	{
+		/* buffer is now unpinned */
 		AddBufferToFreelist(buf);
 		buf->flags |= BM_FREE;
 	}
+	else if ((buf->flags & BM_PIN_COUNT_WAITER) != 0 &&
+			 buf->refcount == 1)
+	{
+		/* we just released the last pin other than the waiter's */
+		buf->flags &= ~BM_PIN_COUNT_WAITER;
+		ProcSendSignal(buf->wait_backend_id);
+	}
 	else
 	{
 		/* do nothing */
@@ -179,18 +190,16 @@ refcount = %ld, file: %s, line: %d\n",
 
 /*
  * GetFreeBuffer() -- get the 'next' buffer from the freelist.
- *
  */
 BufferDesc *
-GetFreeBuffer()
+GetFreeBuffer(void)
 {
 	BufferDesc *buf;
 
 	if (Free_List_Descriptor == SharedFreeList->freeNext)
 	{
-
 		/* queue is empty. All buffers in the buffer pool are pinned. */
-		elog(ERROR, "out of free buffers: time to abort !\n");
+		elog(ERROR, "out of free buffers: time to abort!");
 		return NULL;
 	}
 	buf = &(BufferDescriptors[SharedFreeList->freeNext]);
@@ -220,7 +229,7 @@ InitFreeList(bool init)
 
 	if (init)
 	{
-		/* we only do this once, normally the postmaster */
+		/* we only do this once, normally in the postmaster */
 		SharedFreeList->data = INVALID_OFFSET;
 		SharedFreeList->flags = 0;
 		SharedFreeList->flags &= ~(BM_VALID | BM_DELETED | BM_FREE);
@@ -249,37 +258,23 @@ DBG_FreeListCheck(int nfree)
 	buf = &(BufferDescriptors[SharedFreeList->freeNext]);
 	for (i = 0; i < nfree; i++, buf = &(BufferDescriptors[buf->freeNext]))
 	{
-
 		if (!(buf->flags & (BM_FREE)))
 		{
 			if (buf != SharedFreeList)
-			{
 				printf("\tfree list corrupted: %d flags %x\n",
 					   buf->buf_id, buf->flags);
-			}
 			else
-			{
 				printf("\tfree list corrupted: too short -- %d not %d\n",
 					   i, nfree);
-
-			}
-
-
 		}
 		if ((BufferDescriptors[buf->freeNext].freePrev != buf->buf_id) ||
 			(BufferDescriptors[buf->freePrev].freeNext != buf->buf_id))
-		{
 			printf("\tfree list links corrupted: %d %ld %ld\n",
 				   buf->buf_id, buf->freePrev, buf->freeNext);
-		}
-
 	}
 	if (buf != SharedFreeList)
-	{
 		printf("\tfree list corrupted: %d-th buffer is %d\n",
 			   nfree, buf->buf_id);
-
-	}
 }
 
 #endif

src/backend/storage/ipc/sinval.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.34 2001/06/19 19:42:15 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.35 2001/07/06 21:04:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,7 +16,6 @@
 
 #include <sys/types.h>
 
-#include "storage/backendid.h"
 #include "storage/proc.h"
 #include "storage/sinval.h"
 #include "storage/sinvaladt.h"
@@ -411,3 +410,31 @@ GetUndoRecPtr(void)
 
 	return (urec);
 }
+
+/*
+ * BackendIdGetProc - given a BackendId, find its PROC structure
+ *
+ * This is a trivial lookup in the ProcState array.  We assume that the caller
+ * knows that the backend isn't going to go away, so we do not bother with
+ * locking.
+ */
+struct proc *
+BackendIdGetProc(BackendId procId)
+{
+	SISeg	   *segP = shmInvalBuffer;
+
+	if (procId > 0 && procId <= segP->lastBackend)
+	{
+		ProcState  *stateP = &segP->procState[procId - 1];
+		SHMEM_OFFSET pOffset = stateP->procStruct;
+
+		if (pOffset != INVALID_OFFSET)
+		{
+			PROC	   *proc = (PROC *) MAKE_PTR(pOffset);
+
+			return proc;
+		}
+	}
+
+	return NULL;
+}

src/backend/storage/lmgr/proc.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.103 2001/06/16 22:58:16 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.104 2001/07/06 21:04:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -74,6 +74,7 @@
 
 #include "access/xact.h"
 #include "storage/proc.h"
+#include "storage/sinval.h"
 
 
 int			DeadlockTimeout = 1000;
@@ -92,6 +93,7 @@ static PROC_HDR *ProcGlobal = NULL;
 PROC	   *MyProc = NULL;
 
 static bool waitingForLock = false;
+static bool waitingForSignal = false;
 
 static void ProcKill(void);
 static void ProcGetNewSemIdAndNum(IpcSemaphoreId *semId, int *semNum);
@@ -894,6 +896,49 @@ ProcReleaseSpins(PROC *proc)
 	AbortBufferIO();
 }
 
+/*
+ * ProcWaitForSignal - wait for a signal from another backend.
+ *
+ * This can share the semaphore normally used for waiting for locks,
+ * since a backend could never be waiting for a lock and a signal at
+ * the same time.  As with locks, it's OK if the signal arrives just
+ * before we actually reach the waiting state.
+ */
+void
+ProcWaitForSignal(void)
+{
+	waitingForSignal = true;
+	IpcSemaphoreLock(MyProc->sem.semId, MyProc->sem.semNum, true);
+	waitingForSignal = false;
+}
+
+/*
+ * ProcCancelWaitForSignal - clean up an aborted wait for signal
+ *
+ * We need this in case the signal arrived after we aborted waiting,
+ * or if it arrived but we never reached ProcWaitForSignal() at all.
+ * Caller should call this after resetting the signal request status.
+ */
+void
+ProcCancelWaitForSignal(void)
+{
+	ZeroProcSemaphore(MyProc);
+	waitingForSignal = false;
+}
+
+/*
+ * ProcSendSignal - send a signal to a backend identified by BackendId
+ */
+void
+ProcSendSignal(BackendId procId)
+{
+	PROC   *proc = BackendIdGetProc(procId);
+
+	if (proc != NULL)
+		IpcSemaphoreUnlock(proc->sem.semId, proc->sem.semNum);
+}
+
+
 /*****************************************************************************
  *
  *****************************************************************************/

src/include/storage/buf_internals.h

@@ -7,17 +7,19 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: buf_internals.h,v 1.48 2001/03/22 04:01:05 momjian Exp $
+ * $Id: buf_internals.h,v 1.49 2001/07/06 21:04:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef BUFMGR_INTERNALS_H
 #define BUFMGR_INTERNALS_H
 
+#include "storage/backendid.h"
 #include "storage/buf.h"
 #include "storage/lmgr.h"
 #include "storage/s_lock.h"
 
+
 /* Buf Mgr constants */
 /* in bufmgr.c */
 extern int	Data_Descriptors;
@@ -38,9 +40,19 @@ extern int	ShowPinTrace;
 #define BM_IO_IN_PROGRESS		(1 << 5)
 #define BM_IO_ERROR				(1 << 6)
 #define BM_JUST_DIRTIED			(1 << 7)
+#define BM_PIN_COUNT_WAITER		(1 << 8)
 
 typedef bits16 BufFlags;
 
+/*
+ * Buffer tag identifies which disk block the buffer contains.
+ *
+ * Note: the BufferTag data must be sufficient to determine where to write the
+ * block, even during a "blind write" with no relcache entry.  It's possible
+ * that the backend flushing the buffer doesn't even believe the relation is
+ * visible yet (its xact may have started before the xact that created the
+ * rel).  The storage manager must be able to cope anyway.
+ */
 typedef struct buftag
 {
 	RelFileNode rnode;
@@ -60,28 +72,9 @@ typedef struct buftag
 	(a)->rnode = (xx_reln)->rd_node \
 )
 
-/*
- * We don't need this data any more but it allows more user
- * friendly error messages. Feel free to get rid of it
- * (and change a lot of places -:))
- */
-typedef struct bufblindid
-{
-	char		dbname[NAMEDATALEN];	/* name of db in which buf belongs */
-	char		relname[NAMEDATALEN];	/* name of reln */
-} BufferBlindId;
-
 /*
  *	BufferDesc -- shared buffer cache metadata for a single
  *				  shared buffer descriptor.
- *
- *		We keep the name of the database and relation in which this
- *		buffer appears in order to avoid a catalog lookup on cache
- *		flush if we don't have the reldesc in the cache.  It is also
- *		possible that the relation to which this buffer belongs is
- *		not visible to all backends at the time that it gets flushed.
- *		Dbname, relname, dbid, and relid are enough to determine where
- *		to put the buffer, for all storage managers.
  */
 typedef struct sbufdesc
 {
@@ -89,14 +82,14 @@ typedef struct sbufdesc
 	Buffer		freePrev;
 	SHMEM_OFFSET data;			/* pointer to data in buf pool */
 
-	/* tag and id must be together for table lookup to work */
+	/* tag and id must be together for table lookup (still true?) */
 	BufferTag	tag;			/* file/block identifier */
-	int			buf_id;			/* maps global desc to local desc */
+	int			buf_id;			/* buffer's index number (from 0) */
 
 	BufFlags	flags;			/* see bit definitions above */
-	unsigned	refcount;		/* # of times buffer is pinned */
+	unsigned	refcount;		/* # of backends holding pins on buffer */
 
-	slock_t		io_in_progress_lock;	/* to block for I/O to complete */
+	slock_t		io_in_progress_lock;	/* to wait for I/O to complete */
 	slock_t		cntx_lock;		/* to lock access to page context */
 
 	unsigned	r_locks;		/* # of shared locks */
@@ -105,15 +98,14 @@ typedef struct sbufdesc
 
 	bool		cntxDirty;		/* new way to mark block as dirty */
 
-	BufferBlindId blind;		/* was used to support blind write */
-
 	/*
-	 * When we can't delete item from page (someone else has buffer
-	 * pinned) we mark buffer for cleanup by specifying appropriate for
-	 * buffer content cleanup function. Buffer will be cleaned up from
-	 * release buffer functions.
+	 * We can't physically remove items from a disk page if another backend
+	 * has the buffer pinned.  Hence, a backend may need to wait for all
+	 * other pins to go away.  This is signaled by setting its own backend ID
+	 * into wait_backend_id and setting flag bit BM_PIN_COUNT_WAITER.
+	 * At present, there can be only one such waiter per buffer.
 	 */
-	void		(*CleanupFunc) (Buffer);
+	BackendId	wait_backend_id; /* backend ID of pin-count waiter */
 } BufferDesc;
 
 #define BufferDescriptorGetBuffer(bdesc) ((bdesc)->buf_id + 1)
@@ -128,21 +120,23 @@ typedef struct sbufdesc
 #define BL_R_LOCK			(1 << 1)
 #define BL_RI_LOCK			(1 << 2)
 #define BL_W_LOCK			(1 << 3)
+#define BL_PIN_COUNT_LOCK	(1 << 4)
 
 /*
  *	mao tracing buffer allocation
  */
 
 /*#define BMTRACE*/
+
 #ifdef BMTRACE
 
 typedef struct _bmtrace
 {
 	int			bmt_pid;
-	long		bmt_buf;
-	long		bmt_dbid;
-	long		bmt_relid;
-	int			bmt_blkno;
+	int			bmt_buf;
+	Oid			bmt_dbid;
+	Oid			bmt_relid;
+	BlockNumber	bmt_blkno;
 	int			bmt_op;
 
 #define BMT_NOTUSED		0
@@ -162,9 +156,7 @@ typedef struct _bmtrace
 /* Internal routines: only called by buf.c */
 
 /*freelist.c*/
-extern void AddBufferToFreelist(BufferDesc *bf);
 extern void PinBuffer(BufferDesc *buf);
-extern void PinBuffer_Debug(char *file, int line, BufferDesc *buf);
 extern void UnpinBuffer(BufferDesc *buf);
 extern BufferDesc *GetFreeBuffer(void);
 extern void InitFreeList(bool init);
@@ -179,7 +171,6 @@ extern bool BufTableInsert(BufferDesc *buf);
 extern BufferDesc *BufferDescriptors;
 extern bits8 *BufferLocks;
 extern BufferTag *BufferTagLastDirtied;
-extern BufferBlindId *BufferBlindLastDirtied;
 extern LockRelId *BufferRelidLastDirtied;
 extern bool *BufferDirtiedByMe;
 extern SPINLOCK BufMgrLock;

src/include/storage/bufmgr.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: bufmgr.h,v 1.53 2001/06/29 21:08:25 tgl Exp $
+ * $Id: bufmgr.h,v 1.54 2001/07/06 21:04:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -167,7 +167,7 @@ extern void InitBufferPoolAccess(void);
 extern void PrintBufferUsage(FILE *statfp);
 extern void ResetBufferUsage(void);
 extern void ResetBufferPool(bool isCommit);
-extern int	BufferPoolCheckLeak(void);
+extern bool BufferPoolCheckLeak(void);
 extern void FlushBufferPool(void);
 extern BlockNumber BufferGetBlockNumber(Buffer buffer);
 extern BlockNumber RelationGetNumberOfBlocks(Relation relation);
@@ -183,10 +183,9 @@ extern void SetBufferCommitInfoNeedsSave(Buffer buffer);
 
 extern void UnlockBuffers(void);
 extern void LockBuffer(Buffer buffer, int mode);
-extern void AbortBufferIO(void);
+extern void LockBufferForCleanup(Buffer buffer);
 
-extern bool BufferIsUpdatable(Buffer buffer);
-extern void MarkBufferForCleanup(Buffer buffer, void (*CleanupFunc) (Buffer));
+extern void AbortBufferIO(void);
 
 extern void BufmgrCommit(void);
 extern void BufferSync(void);

src/include/storage/proc.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: proc.h,v 1.44 2001/06/16 22:58:17 tgl Exp $
+ * $Id: proc.h,v 1.45 2001/07/06 21:04:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -15,6 +15,7 @@
 #define _PROC_H_
 
 #include "access/xlog.h"
+#include "storage/backendid.h"
 #include "storage/lock.h"
 
 /* configurable option */
@@ -139,4 +140,8 @@ extern void ProcReleaseSpins(PROC *proc);
 extern bool LockWaitCancel(void);
 extern void HandleDeadLock(SIGNAL_ARGS);
 
+extern void ProcWaitForSignal(void);
+extern void ProcCancelWaitForSignal(void);
+extern void ProcSendSignal(BackendId procId);
+
 #endif	 /* PROC_H */

src/include/storage/sinval.h

@@ -7,13 +7,14 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: sinval.h,v 1.19 2001/06/19 19:42:16 tgl Exp $
+ * $Id: sinval.h,v 1.20 2001/07/06 21:04:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef SINVAL_H
 #define SINVAL_H
 
+#include "storage/backendid.h"
 #include "storage/itemptr.h"
 #include "storage/spin.h"
 
@@ -77,5 +78,7 @@ extern bool DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself);
 extern bool TransactionIdIsInProgress(TransactionId xid);
 extern void GetXmaxRecent(TransactionId *XmaxRecent);
 extern int	CountActiveBackends(void);
+/* Use "struct proc", not PROC, to avoid including proc.h here */
+extern struct proc *BackendIdGetProc(BackendId procId);
 
 #endif	 /* SINVAL_H */