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/*-------------------------------------------------------------------------
*
* bufmgr.h
* POSTGRES buffer manager definitions.
*
*
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: bufmgr.h,v 1.39 2000/06/15 03:33:00 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef BUFMGR_H
#define BUFMGR_H
#include "storage/buf_internals.h"
/*
* the maximum size of a disk block for any possible installation.
*
* in theory this could be anything, but in practice this is actually
* limited to 2^13 bytes because we have limited ItemIdData.lp_off and
* ItemIdData.lp_len to 13 bits (see itemid.h).
*
* limit is now 2^15. Took four bits from ItemIdData.lp_flags and gave
* two apiece to ItemIdData.lp_len and lp_off. darrenk 01/06/98
*
*/
#define MAXBLCKSZ 32768
typedef void *Block;
/* special pageno for bget */
#define P_NEW InvalidBlockNumber /* grow the file to get a new page */
typedef bits16 BufferLock;
/**********************************************************************
the rest is function defns in the bufmgr that are externally callable
**********************************************************************/
/*
* These routines are beaten on quite heavily, hence the macroization.
* See buf_internals.h for a related comment.
*/
#define BufferDescriptorGetBuffer(bdesc) ((bdesc)->buf_id + 1)
extern int ShowPinTrace;
/*
* Buffer context lock modes
*/
#define BUFFER_LOCK_UNLOCK 0
#define BUFFER_LOCK_SHARE 1
#define BUFFER_LOCK_EXCLUSIVE 2
/*
* BufferIsValid
* True iff the given buffer number is valid (either as a shared
* or local buffer).
*
* Note:
* BufferIsValid(InvalidBuffer) is False.
* BufferIsValid(UnknownBuffer) is False.
*
* Note: For a long time this was defined the same as BufferIsPinned,
* that is it would say False if you didn't hold a pin on the buffer.
* I believe this was bogus and served only to mask logic errors.
* Code should always know whether it has a buffer reference,
* independently of the pin state.
*/
#define BufferIsValid(bufnum) \
( \
BufferIsLocal(bufnum) ? \
((bufnum) >= -NLocBuffer) \
: \
(! BAD_BUFFER_ID(bufnum)) \
)
/*
* BufferIsPinned
* True iff the buffer is pinned (also checks for valid buffer number).
*
* NOTE: what we check here is that *this* backend holds a pin on
* the buffer. We do not care whether some other backend does.
*/
#define BufferIsPinned(bufnum) \
( \
BufferIsLocal(bufnum) ? \
((bufnum) >= -NLocBuffer && LocalRefCount[-(bufnum) - 1] > 0) \
: \
( \
BAD_BUFFER_ID(bufnum) ? \
false \
: \
(PrivateRefCount[(bufnum) - 1] > 0) \
) \
)
/*
* IncrBufferRefCount
* Increment the pin count on a buffer that we have *already* pinned
* at least once.
*
* This macro cannot be used on a buffer we do not have pinned,
* because it doesn't change the shared buffer state. Therefore the
* Assert checks are for refcount > 0. Someone got this wrong once...
*/
#define IncrBufferRefCount(buffer) \
( \
BufferIsLocal(buffer) ? \
( \
(void) AssertMacro((buffer) >= -NLocBuffer), \
(void) AssertMacro(LocalRefCount[-(buffer) - 1] > 0), \
(void) LocalRefCount[-(buffer) - 1]++ \
) \
: \
( \
(void) AssertMacro(!BAD_BUFFER_ID(buffer)), \
(void) AssertMacro(PrivateRefCount[(buffer) - 1] > 0), \
(void) PrivateRefCount[(buffer) - 1]++ \
) \
)
/*
* BufferGetBlock
* Returns a reference to a disk page image associated with a buffer.
*
* Note:
* Assumes buffer is valid.
*/
#define BufferGetBlock(buffer) \
( \
AssertMacro(BufferIsValid(buffer)), \
BufferIsLocal(buffer) ? \
((Block) MAKE_PTR(LocalBufferDescriptors[-(buffer) - 1].data)) \
: \
((Block) MAKE_PTR(BufferDescriptors[(buffer) - 1].data)) \
)
/*
* prototypes for functions in bufmgr.c
*/
extern Buffer RelationGetBufferWithBuffer(Relation relation,
BlockNumber blockNumber, Buffer buffer);
extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
extern int WriteBuffer(Buffer buffer);
extern int WriteNoReleaseBuffer(Buffer buffer);
extern Buffer ReleaseAndReadBuffer(Buffer buffer, Relation relation,
BlockNumber blockNum);
extern int FlushBuffer(Buffer buffer, bool release);
extern void InitBufferPool(IPCKey key);
extern void PrintBufferUsage(FILE *statfp);
extern void ResetBufferUsage(void);
extern void ResetBufferPool(bool isCommit);
extern int BufferPoolCheckLeak(void);
extern void FlushBufferPool(void);
extern BlockNumber BufferGetBlockNumber(Buffer buffer);
extern BlockNumber RelationGetNumberOfBlocks(Relation relation);
extern int FlushRelationBuffers(Relation rel, BlockNumber firstDelBlock);
extern void ReleaseRelationBuffers(Relation rel);
extern void DropBuffers(Oid dbid);
extern void PrintPinnedBufs(void);
extern int BufferShmemSize(void);
extern int ReleaseBuffer(Buffer buffer);
extern void SetBufferCommitInfoNeedsSave(Buffer buffer);
extern void UnlockBuffers(void);
extern void LockBuffer(Buffer buffer, int mode);
extern void AbortBufferIO(void);
#endif
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