src/include/storage/bufmgr.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * bufmgr.h
   4  *        POSTGRES buffer manager definitions.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2009, 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_BULKWRITE,                          /* Large multi-block write (e.g. COPY IN) */
  32         BAS_VACUUM                                      /* VACUUM */
  33 } BufferAccessStrategyType;
  34
  35 /* Possible modes for ReadBufferExtended() */
  36 typedef enum
  37 {
  38         RBM_NORMAL,                                     /* Normal read */
  39         RBM_ZERO,                                       /* Don't read from disk, caller will
  40                                                                  * initialize */
  41         RBM_ZERO_ON_ERROR                       /* Read, but return an all-zeros page on error */
  42 } ReadBufferMode;
  43
  44 /* in globals.c ... this duplicates miscadmin.h */
  45 extern PGDLLIMPORT int NBuffers;
  46
  47 /* in bufmgr.c */
  48 extern bool zero_damaged_pages;
  49 extern int      bgwriter_lru_maxpages;
  50 extern double bgwriter_lru_multiplier;
  51 extern int      target_prefetch_pages;
  52
  53 /* in buf_init.c */
  54 extern PGDLLIMPORT char *BufferBlocks;
  55 extern PGDLLIMPORT int32 *PrivateRefCount;
  56
  57 /* in localbuf.c */
  58 extern PGDLLIMPORT int NLocBuffer;
  59 extern PGDLLIMPORT Block *LocalBufferBlockPointers;
  60 extern PGDLLIMPORT int32 *LocalRefCount;
  61
  62 /* special block number for ReadBuffer() */
  63 #define P_NEW   InvalidBlockNumber              /* grow the file to get a new page */
  64
  65 /*
  66  * Buffer content lock modes (mode argument for LockBuffer())
  67  */
  68 #define BUFFER_LOCK_UNLOCK              0
  69 #define BUFFER_LOCK_SHARE               1
  70 #define BUFFER_LOCK_EXCLUSIVE   2
  71
  72 /*
  73  * These routines are beaten on quite heavily, hence the macroization.
  74  */
  75
  76 /*
  77  * BufferIsValid
  78  *              True iff the given buffer number is valid (either as a shared
  79  *              or local buffer).
  80  *
  81  * This is not quite the inverse of the BufferIsInvalid() macro, since this
  82  * adds sanity rangechecks on the buffer number.
  83  *
  84  * Note: For a long time this was defined the same as BufferIsPinned,
  85  * that is it would say False if you didn't hold a pin on the buffer.
  86  * I believe this was bogus and served only to mask logic errors.
  87  * Code should always know whether it has a buffer reference,
  88  * independently of the pin state.
  89  */
  90 #define BufferIsValid(bufnum) \
  91 ( \
  92         (bufnum) != InvalidBuffer && \
  93         (bufnum) >= -NLocBuffer && \
  94         (bufnum) <= NBuffers \
  95 )
  96
  97 /*
  98  * BufferIsPinned
  99  *              True iff the buffer is pinned (also checks for valid buffer number).
 100  *
 101  *              NOTE: what we check here is that *this* backend holds a pin on
 102  *              the buffer.  We do not care whether some other backend does.
 103  */
 104 #define BufferIsPinned(bufnum) \
 105 ( \
 106         !BufferIsValid(bufnum) ? \
 107                 false \
 108         : \
 109                 BufferIsLocal(bufnum) ? \
 110                         (LocalRefCount[-(bufnum) - 1] > 0) \
 111                 : \
 112                         (PrivateRefCount[(bufnum) - 1] > 0) \
 113 )
 114
 115 /*
 116  * BufferGetBlock
 117  *              Returns a reference to a disk page image associated with a buffer.
 118  *
 119  * Note:
 120  *              Assumes buffer is valid.
 121  */
 122 #define BufferGetBlock(buffer) \
 123 ( \
 124         AssertMacro(BufferIsValid(buffer)), \
 125         BufferIsLocal(buffer) ? \
 126                 LocalBufferBlockPointers[-(buffer) - 1] \
 127         : \
 128                 (Block) (BufferBlocks + ((Size) ((buffer) - 1)) * BLCKSZ) \
 129 )
 130
 131 /*
 132  * BufferGetPageSize
 133  *              Returns the page size within a buffer.
 134  *
 135  * Notes:
 136  *              Assumes buffer is valid.
 137  *
 138  *              The buffer can be a raw disk block and need not contain a valid
 139  *              (formatted) disk page.
 140  */
 141 /* XXX should dig out of buffer descriptor */
 142 #define BufferGetPageSize(buffer) \
 143 ( \
 144         AssertMacro(BufferIsValid(buffer)), \
 145         (Size)BLCKSZ \
 146 )
 147
 148 /*
 149  * BufferGetPage
 150  *              Returns the page associated with a buffer.
 151  */
 152 #define BufferGetPage(buffer) ((Page)BufferGetBlock(buffer))
 153
 154 /*
 155  * prototypes for functions in bufmgr.c
 156  */
 157 extern void PrefetchBuffer(Relation reln, ForkNumber forkNum,
 158                            BlockNumber blockNum);
 159 extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
 160 extern Buffer ReadBufferExtended(Relation reln, ForkNumber forkNum,
 161                                    BlockNumber blockNum, ReadBufferMode mode,
 162                                    BufferAccessStrategy strategy);
 163 extern Buffer ReadBufferWithoutRelcache(RelFileNode rnode, bool isTemp,
 164                                                   ForkNumber forkNum, BlockNumber blockNum,
 165                                                   ReadBufferMode mode, BufferAccessStrategy strategy);
 166 extern void ReleaseBuffer(Buffer buffer);
 167 extern void UnlockReleaseBuffer(Buffer buffer);
 168 extern void MarkBufferDirty(Buffer buffer);
 169 extern void IncrBufferRefCount(Buffer buffer);
 170 extern Buffer ReleaseAndReadBuffer(Buffer buffer, Relation relation,
 171                                          BlockNumber blockNum);
 172
 173 extern void InitBufferPool(void);
 174 extern void InitBufferPoolAccess(void);
 175 extern void InitBufferPoolBackend(void);
 176 extern char *ShowBufferUsage(void);
 177 extern void ResetBufferUsage(void);
 178 extern void AtEOXact_Buffers(bool isCommit);
 179 extern void PrintBufferLeakWarning(Buffer buffer);
 180 extern void CheckPointBuffers(int flags);
 181 extern BlockNumber BufferGetBlockNumber(Buffer buffer);
 182 extern BlockNumber RelationGetNumberOfBlocks(Relation relation);
 183 extern void FlushRelationBuffers(Relation rel);
 184 extern void FlushDatabaseBuffers(Oid dbid);
 185 extern void DropRelFileNodeBuffers(RelFileNode rnode, ForkNumber forkNum,
 186                                            bool istemp, BlockNumber firstDelBlock);
 187 extern void DropDatabaseBuffers(Oid dbid);
 188
 189 #ifdef NOT_USED
 190 extern void PrintPinnedBufs(void);
 191 #endif
 192 extern Size BufferShmemSize(void);
 193 extern void BufferGetTag(Buffer buffer, RelFileNode *rnode,
 194                          ForkNumber *forknum, BlockNumber *blknum);
 195
 196 extern void SetBufferCommitInfoNeedsSave(Buffer buffer);
 197
 198 extern void UnlockBuffers(void);
 199 extern void LockBuffer(Buffer buffer, int mode);
 200 extern bool ConditionalLockBuffer(Buffer buffer);
 201 extern void LockBufferForCleanup(Buffer buffer);
 202 extern bool ConditionalLockBufferForCleanup(Buffer buffer);
 203
 204 extern void AbortBufferIO(void);
 205
 206 extern void BufmgrCommit(void);
 207 extern void BgBufferSync(void);
 208
 209 extern void AtProcExit_LocalBuffers(void);
 210
 211 /* in freelist.c */
 212 extern BufferAccessStrategy GetAccessStrategy(BufferAccessStrategyType btype);
 213 extern void FreeAccessStrategy(BufferAccessStrategy strategy);
 214
 215 #endif