src/include/storage/bufmgr.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * bufmgr.h
   4  *        POSTGRES buffer manager definitions.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef BUFMGR_H
  15 #define BUFMGR_H
  16
  17 #include "storage/block.h"
  18 #include "storage/buf.h"
  19 #include "storage/bufpage.h"
  20 #include "storage/relfilenode.h"
  21 #include "utils/relcache.h"
  22
  23 typedef void *Block;
  24
  25 /* Possible arguments for GetAccessStrategy() */
  26 typedef enum BufferAccessStrategyType
  27 {
  28         BAS_NORMAL,                                     /* Normal random access */
  29         BAS_BULKREAD,                           /* Large read-only scan (hint bit updates are
  30                                                                  * ok) */
  31         BAS_VACUUM                                      /* VACUUM */
  32 } BufferAccessStrategyType;
  33
  34 /* in globals.c ... this duplicates miscadmin.h */
  35 extern PGDLLIMPORT int NBuffers;
  36
  37 /* in bufmgr.c */
  38 extern bool zero_damaged_pages;
  39 extern int      bgwriter_lru_maxpages;
  40 extern double bgwriter_lru_multiplier;
  41
  42 /* in buf_init.c */
  43 extern PGDLLIMPORT char *BufferBlocks;
  44 extern PGDLLIMPORT int32 *PrivateRefCount;
  45
  46 /* in localbuf.c */
  47 extern PGDLLIMPORT int NLocBuffer;
  48 extern PGDLLIMPORT Block *LocalBufferBlockPointers;
  49 extern PGDLLIMPORT int32 *LocalRefCount;
  50
  51 /* special block number for ReadBuffer() */
  52 #define P_NEW   InvalidBlockNumber              /* grow the file to get a new page */
  53
  54 /*
  55  * Buffer content lock modes (mode argument for LockBuffer())
  56  */
  57 #define BUFFER_LOCK_UNLOCK              0
  58 #define BUFFER_LOCK_SHARE               1
  59 #define BUFFER_LOCK_EXCLUSIVE   2
  60
  61 /*
  62  * These routines are beaten on quite heavily, hence the macroization.
  63  */
  64
  65 /*
  66  * BufferIsValid
  67  *              True iff the given buffer number is valid (either as a shared
  68  *              or local buffer).
  69  *
  70  * This is not quite the inverse of the BufferIsInvalid() macro, since this
  71  * adds sanity rangechecks on the buffer number.
  72  *
  73  * Note: For a long time this was defined the same as BufferIsPinned,
  74  * that is it would say False if you didn't hold a pin on the buffer.
  75  * I believe this was bogus and served only to mask logic errors.
  76  * Code should always know whether it has a buffer reference,
  77  * independently of the pin state.
  78  */
  79 #define BufferIsValid(bufnum) \
  80 ( \
  81         (bufnum) != InvalidBuffer && \
  82         (bufnum) >= -NLocBuffer && \
  83         (bufnum) <= NBuffers \
  84 )
  85
  86 /*
  87  * BufferIsPinned
  88  *              True iff the buffer is pinned (also checks for valid buffer number).
  89  *
  90  *              NOTE: what we check here is that *this* backend holds a pin on
  91  *              the buffer.  We do not care whether some other backend does.
  92  */
  93 #define BufferIsPinned(bufnum) \
  94 ( \
  95         !BufferIsValid(bufnum) ? \
  96                 false \
  97         : \
  98                 BufferIsLocal(bufnum) ? \
  99                         (LocalRefCount[-(bufnum) - 1] > 0) \
 100                 : \
 101                         (PrivateRefCount[(bufnum) - 1] > 0) \
 102 )
 103
 104 /*
 105  * BufferGetBlock
 106  *              Returns a reference to a disk page image associated with a buffer.
 107  *
 108  * Note:
 109  *              Assumes buffer is valid.
 110  */
 111 #define BufferGetBlock(buffer) \
 112 ( \
 113         AssertMacro(BufferIsValid(buffer)), \
 114         BufferIsLocal(buffer) ? \
 115                 LocalBufferBlockPointers[-(buffer) - 1] \
 116         : \
 117                 (Block) (BufferBlocks + ((Size) ((buffer) - 1)) * BLCKSZ) \
 118 )
 119
 120 /*
 121  * BufferGetPageSize
 122  *              Returns the page size within a buffer.
 123  *
 124  * Notes:
 125  *              Assumes buffer is valid.
 126  *
 127  *              The buffer can be a raw disk block and need not contain a valid
 128  *              (formatted) disk page.
 129  */
 130 /* XXX should dig out of buffer descriptor */
 131 #define BufferGetPageSize(buffer) \
 132 ( \
 133         AssertMacro(BufferIsValid(buffer)), \
 134         (Size)BLCKSZ \
 135 )
 136
 137 /*
 138  * BufferGetPage
 139  *              Returns the page associated with a buffer.
 140  */
 141 #define BufferGetPage(buffer) ((Page)BufferGetBlock(buffer))
 142
 143 /*
 144  * prototypes for functions in bufmgr.c
 145  */
 146 extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
 147 extern Buffer ReadBufferWithFork(Relation reln, ForkNumber forkNum, BlockNumber blockNum);
 148 extern Buffer ReadBufferWithStrategy(Relation reln, BlockNumber blockNum,
 149                                            BufferAccessStrategy strategy);
 150 extern Buffer ReadOrZeroBuffer(Relation reln, ForkNumber forkNum,
 151                                                            BlockNumber blockNum);
 152 extern Buffer ReadBufferWithoutRelcache(RelFileNode rnode, bool isTemp,
 153                                         ForkNumber forkNum, BlockNumber blockNum, bool zeroPage);
 154 extern void ReleaseBuffer(Buffer buffer);
 155 extern void UnlockReleaseBuffer(Buffer buffer);
 156 extern void MarkBufferDirty(Buffer buffer);
 157 extern void IncrBufferRefCount(Buffer buffer);
 158 extern Buffer ReleaseAndReadBuffer(Buffer buffer, Relation relation,
 159                                          BlockNumber blockNum);
 160
 161 extern void InitBufferPool(void);
 162 extern void InitBufferPoolAccess(void);
 163 extern void InitBufferPoolBackend(void);
 164 extern char *ShowBufferUsage(void);
 165 extern void ResetBufferUsage(void);
 166 extern void AtEOXact_Buffers(bool isCommit);
 167 extern void PrintBufferLeakWarning(Buffer buffer);
 168 extern void CheckPointBuffers(int flags);
 169 extern BlockNumber BufferGetBlockNumber(Buffer buffer);
 170 extern BlockNumber RelationGetNumberOfBlocks(Relation relation);
 171 extern void RelationTruncate(Relation rel, BlockNumber nblocks);
 172 extern void FlushRelationBuffers(Relation rel);
 173 extern void FlushDatabaseBuffers(Oid dbid);
 174 extern void DropRelFileNodeBuffers(RelFileNode rnode, ForkNumber forkNum,
 175                                            bool istemp, BlockNumber firstDelBlock);
 176 extern void DropDatabaseBuffers(Oid dbid);
 177
 178 #ifdef NOT_USED
 179 extern void PrintPinnedBufs(void);
 180 #endif
 181 extern Size BufferShmemSize(void);
 182 extern void BufferGetTag(Buffer buffer, RelFileNode *rnode,
 183                                                  ForkNumber *forknum, BlockNumber *blknum);
 184
 185 extern void SetBufferCommitInfoNeedsSave(Buffer buffer);
 186
 187 extern void UnlockBuffers(void);
 188 extern void LockBuffer(Buffer buffer, int mode);
 189 extern bool ConditionalLockBuffer(Buffer buffer);
 190 extern void LockBufferForCleanup(Buffer buffer);
 191 extern bool ConditionalLockBufferForCleanup(Buffer buffer);
 192
 193 extern void AbortBufferIO(void);
 194
 195 extern void BufmgrCommit(void);
 196 extern void BgBufferSync(void);
 197
 198 extern void AtProcExit_LocalBuffers(void);
 199
 200 /* in freelist.c */
 201 extern BufferAccessStrategy GetAccessStrategy(BufferAccessStrategyType btype);
 202 extern void FreeAccessStrategy(BufferAccessStrategy strategy);
 203
 204 #endif