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a8b8f4db23
misleadingly-named WriteBuffer routine, and instead require routines that change buffer pages to call MarkBufferDirty (which does exactly what it says). We also require that they do so before calling XLogInsert; this takes care of the synchronization requirement documented in SyncOneBuffer. Note that because bufmgr takes the buffer content lock (in shared mode) while writing out any buffer, it doesn't matter whether MarkBufferDirty is executed before the buffer content change is complete, so long as the content change is completed before releasing exclusive lock on the buffer. So it's OK to set the dirtybit before we fill in the LSN. This eliminates the former kluge of needing to set the dirtybit in LockBuffer. Aside from making the code more transparent, we can also add some new debugging assertions, in particular that the caller of MarkBufferDirty must hold the buffer content lock, not merely a pin.
164 lines
4.6 KiB
C
164 lines
4.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* bufmgr.h
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* POSTGRES buffer manager definitions.
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*
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*
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* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.100 2006/03/31 23:32:07 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef BUFMGR_H
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#define BUFMGR_H
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#include "access/xlogdefs.h"
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#include "storage/buf.h"
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#include "storage/lock.h"
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#include "storage/relfilenode.h"
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#include "utils/rel.h"
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typedef void *Block;
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/* in globals.c ... this duplicates miscadmin.h */
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extern DLLIMPORT int NBuffers;
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/* in bufmgr.c */
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extern bool zero_damaged_pages;
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extern double bgwriter_lru_percent;
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extern double bgwriter_all_percent;
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extern int bgwriter_lru_maxpages;
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extern int bgwriter_all_maxpages;
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/* in buf_init.c */
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extern DLLIMPORT char *BufferBlocks;
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extern DLLIMPORT int32 *PrivateRefCount;
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/* in localbuf.c */
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extern DLLIMPORT int NLocBuffer;
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extern DLLIMPORT Block *LocalBufferBlockPointers;
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extern DLLIMPORT int32 *LocalRefCount;
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/* special block number for ReadBuffer() */
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#define P_NEW InvalidBlockNumber /* grow the file to get a new page */
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/*
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* Buffer content lock modes (mode argument for LockBuffer())
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*/
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#define BUFFER_LOCK_UNLOCK 0
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#define BUFFER_LOCK_SHARE 1
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#define BUFFER_LOCK_EXCLUSIVE 2
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/*
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* These routines are beaten on quite heavily, hence the macroization.
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*/
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/*
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* BufferIsValid
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* True iff the given buffer number is valid (either as a shared
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* or local buffer).
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*
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* This is not quite the inverse of the BufferIsInvalid() macro, since this
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* adds sanity rangechecks on the buffer number.
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*
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* Note: For a long time this was defined the same as BufferIsPinned,
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* that is it would say False if you didn't hold a pin on the buffer.
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* I believe this was bogus and served only to mask logic errors.
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* Code should always know whether it has a buffer reference,
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* independently of the pin state.
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*/
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#define BufferIsValid(bufnum) \
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( \
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(bufnum) != InvalidBuffer && \
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(bufnum) >= -NLocBuffer && \
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(bufnum) <= NBuffers \
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)
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/*
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* BufferIsPinned
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* True iff the buffer is pinned (also checks for valid buffer number).
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*
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* NOTE: what we check here is that *this* backend holds a pin on
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* the buffer. We do not care whether some other backend does.
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*/
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#define BufferIsPinned(bufnum) \
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( \
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!BufferIsValid(bufnum) ? \
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false \
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: \
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BufferIsLocal(bufnum) ? \
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(LocalRefCount[-(bufnum) - 1] > 0) \
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: \
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(PrivateRefCount[(bufnum) - 1] > 0) \
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)
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/*
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* BufferGetBlock
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* Returns a reference to a disk page image associated with a buffer.
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*
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* Note:
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* Assumes buffer is valid.
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*/
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#define BufferGetBlock(buffer) \
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( \
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AssertMacro(BufferIsValid(buffer)), \
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BufferIsLocal(buffer) ? \
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LocalBufferBlockPointers[-(buffer) - 1] \
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: \
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(Block) (BufferBlocks + ((Size) ((buffer) - 1)) * BLCKSZ) \
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)
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/*
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* prototypes for functions in bufmgr.c
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*/
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extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
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extern void ReleaseBuffer(Buffer buffer);
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extern void UnlockReleaseBuffer(Buffer buffer);
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extern void MarkBufferDirty(Buffer buffer);
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extern void IncrBufferRefCount(Buffer buffer);
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extern Buffer ReleaseAndReadBuffer(Buffer buffer, Relation relation,
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BlockNumber blockNum);
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extern void InitBufferPool(void);
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extern void InitBufferPoolAccess(void);
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extern void InitBufferPoolBackend(void);
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extern char *ShowBufferUsage(void);
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extern void ResetBufferUsage(void);
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extern void AtEOXact_Buffers(bool isCommit);
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extern void PrintBufferLeakWarning(Buffer buffer);
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extern void FlushBufferPool(void);
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extern BlockNumber BufferGetBlockNumber(Buffer buffer);
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extern BlockNumber RelationGetNumberOfBlocks(Relation relation);
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extern void RelationTruncate(Relation rel, BlockNumber nblocks);
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extern void FlushRelationBuffers(Relation rel);
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extern void DropRelFileNodeBuffers(RelFileNode rnode, bool istemp,
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BlockNumber firstDelBlock);
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extern void DropDatabaseBuffers(Oid dbid);
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#ifdef NOT_USED
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extern void PrintPinnedBufs(void);
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#endif
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extern Size BufferShmemSize(void);
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extern RelFileNode BufferGetFileNode(Buffer buffer);
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extern void SetBufferCommitInfoNeedsSave(Buffer buffer);
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extern void UnlockBuffers(void);
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extern void LockBuffer(Buffer buffer, int mode);
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extern bool ConditionalLockBuffer(Buffer buffer);
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extern void LockBufferForCleanup(Buffer buffer);
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extern void AbortBufferIO(void);
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extern void BufmgrCommit(void);
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extern void BufferSync(void);
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extern void BgBufferSync(void);
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extern void AtProcExit_LocalBuffers(void);
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/* in freelist.c */
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extern void StrategyHintVacuum(bool vacuum_active);
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#endif
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