LCOV - code coverage report
Current view: top level - src/include/storage - bufmgr.h (source / functions) Hit Total Coverage
Test: PostgreSQL 13devel Lines: 9 9 100.0 %
Date: 2019-11-15 23:07:02 Functions: 1 1 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * bufmgr.h
       4             :  *    POSTGRES buffer manager definitions.
       5             :  *
       6             :  *
       7             :  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
       8             :  * Portions Copyright (c) 1994, Regents of the University of California
       9             :  *
      10             :  * src/include/storage/bufmgr.h
      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             : #include "utils/snapmgr.h"
      23             : 
      24             : typedef void *Block;
      25             : 
      26             : /* Possible arguments for GetAccessStrategy() */
      27             : typedef enum BufferAccessStrategyType
      28             : {
      29             :     BAS_NORMAL,                 /* Normal random access */
      30             :     BAS_BULKREAD,               /* Large read-only scan (hint bit updates are
      31             :                                  * ok) */
      32             :     BAS_BULKWRITE,              /* Large multi-block write (e.g. COPY IN) */
      33             :     BAS_VACUUM                  /* VACUUM */
      34             : } BufferAccessStrategyType;
      35             : 
      36             : /* Possible modes for ReadBufferExtended() */
      37             : typedef enum
      38             : {
      39             :     RBM_NORMAL,                 /* Normal read */
      40             :     RBM_ZERO_AND_LOCK,          /* Don't read from disk, caller will
      41             :                                  * initialize. Also locks the page. */
      42             :     RBM_ZERO_AND_CLEANUP_LOCK,  /* Like RBM_ZERO_AND_LOCK, but locks the page
      43             :                                  * in "cleanup" mode */
      44             :     RBM_ZERO_ON_ERROR,          /* Read, but return an all-zeros page on error */
      45             :     RBM_NORMAL_NO_LOG           /* Don't log page as invalid during WAL
      46             :                                  * replay; otherwise same as RBM_NORMAL */
      47             : } ReadBufferMode;
      48             : 
      49             : /* forward declared, to avoid having to expose buf_internals.h here */
      50             : struct WritebackContext;
      51             : 
      52             : /* in globals.c ... this duplicates miscadmin.h */
      53             : extern PGDLLIMPORT int NBuffers;
      54             : 
      55             : /* in bufmgr.c */
      56             : extern bool zero_damaged_pages;
      57             : extern int  bgwriter_lru_maxpages;
      58             : extern double bgwriter_lru_multiplier;
      59             : extern bool track_io_timing;
      60             : extern int  target_prefetch_pages;
      61             : 
      62             : extern int  checkpoint_flush_after;
      63             : extern int  backend_flush_after;
      64             : extern int  bgwriter_flush_after;
      65             : 
      66             : /* in buf_init.c */
      67             : extern PGDLLIMPORT char *BufferBlocks;
      68             : 
      69             : /* in guc.c */
      70             : extern int  effective_io_concurrency;
      71             : 
      72             : /* in localbuf.c */
      73             : extern PGDLLIMPORT int NLocBuffer;
      74             : extern PGDLLIMPORT Block *LocalBufferBlockPointers;
      75             : extern PGDLLIMPORT int32 *LocalRefCount;
      76             : 
      77             : /* upper limit for effective_io_concurrency */
      78             : #define MAX_IO_CONCURRENCY 1000
      79             : 
      80             : /* special block number for ReadBuffer() */
      81             : #define P_NEW   InvalidBlockNumber  /* grow the file to get a new page */
      82             : 
      83             : /*
      84             :  * Buffer content lock modes (mode argument for LockBuffer())
      85             :  */
      86             : #define BUFFER_LOCK_UNLOCK      0
      87             : #define BUFFER_LOCK_SHARE       1
      88             : #define BUFFER_LOCK_EXCLUSIVE   2
      89             : 
      90             : /*
      91             :  * These routines are beaten on quite heavily, hence the macroization.
      92             :  */
      93             : 
      94             : /*
      95             :  * BufferIsValid
      96             :  *      True iff the given buffer number is valid (either as a shared
      97             :  *      or local buffer).
      98             :  *
      99             :  * Note: For a long time this was defined the same as BufferIsPinned,
     100             :  * that is it would say False if you didn't hold a pin on the buffer.
     101             :  * I believe this was bogus and served only to mask logic errors.
     102             :  * Code should always know whether it has a buffer reference,
     103             :  * independently of the pin state.
     104             :  *
     105             :  * Note: For a further long time this was not quite the inverse of the
     106             :  * BufferIsInvalid() macro, in that it also did sanity checks to verify
     107             :  * that the buffer number was in range.  Most likely, this macro was
     108             :  * originally intended only to be used in assertions, but its use has
     109             :  * since expanded quite a bit, and the overhead of making those checks
     110             :  * even in non-assert-enabled builds can be significant.  Thus, we've
     111             :  * now demoted the range checks to assertions within the macro itself.
     112             :  */
     113             : #define BufferIsValid(bufnum) \
     114             : ( \
     115             :     AssertMacro((bufnum) <= NBuffers && (bufnum) >= -NLocBuffer), \
     116             :     (bufnum) != InvalidBuffer  \
     117             : )
     118             : 
     119             : /*
     120             :  * BufferGetBlock
     121             :  *      Returns a reference to a disk page image associated with a buffer.
     122             :  *
     123             :  * Note:
     124             :  *      Assumes buffer is valid.
     125             :  */
     126             : #define BufferGetBlock(buffer) \
     127             : ( \
     128             :     AssertMacro(BufferIsValid(buffer)), \
     129             :     BufferIsLocal(buffer) ? \
     130             :         LocalBufferBlockPointers[-(buffer) - 1] \
     131             :     : \
     132             :         (Block) (BufferBlocks + ((Size) ((buffer) - 1)) * BLCKSZ) \
     133             : )
     134             : 
     135             : /*
     136             :  * BufferGetPageSize
     137             :  *      Returns the page size within a buffer.
     138             :  *
     139             :  * Notes:
     140             :  *      Assumes buffer is valid.
     141             :  *
     142             :  *      The buffer can be a raw disk block and need not contain a valid
     143             :  *      (formatted) disk page.
     144             :  */
     145             : /* XXX should dig out of buffer descriptor */
     146             : #define BufferGetPageSize(buffer) \
     147             : ( \
     148             :     AssertMacro(BufferIsValid(buffer)), \
     149             :     (Size)BLCKSZ \
     150             : )
     151             : 
     152             : /*
     153             :  * BufferGetPage
     154             :  *      Returns the page associated with a buffer.
     155             :  *
     156             :  * When this is called as part of a scan, there may be a need for a nearby
     157             :  * call to TestForOldSnapshot().  See the definition of that for details.
     158             :  */
     159             : #define BufferGetPage(buffer) ((Page)BufferGetBlock(buffer))
     160             : 
     161             : /*
     162             :  * prototypes for functions in bufmgr.c
     163             :  */
     164             : extern bool ComputeIoConcurrency(int io_concurrency, double *target);
     165             : extern void PrefetchBuffer(Relation reln, ForkNumber forkNum,
     166             :                            BlockNumber blockNum);
     167             : extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
     168             : extern Buffer ReadBufferExtended(Relation reln, ForkNumber forkNum,
     169             :                                  BlockNumber blockNum, ReadBufferMode mode,
     170             :                                  BufferAccessStrategy strategy);
     171             : extern Buffer ReadBufferWithoutRelcache(RelFileNode rnode,
     172             :                                         ForkNumber forkNum, BlockNumber blockNum,
     173             :                                         ReadBufferMode mode, BufferAccessStrategy strategy);
     174             : extern void ReleaseBuffer(Buffer buffer);
     175             : extern void UnlockReleaseBuffer(Buffer buffer);
     176             : extern void MarkBufferDirty(Buffer buffer);
     177             : extern void IncrBufferRefCount(Buffer buffer);
     178             : extern Buffer ReleaseAndReadBuffer(Buffer buffer, Relation relation,
     179             :                                    BlockNumber blockNum);
     180             : 
     181             : extern void InitBufferPool(void);
     182             : extern void InitBufferPoolAccess(void);
     183             : extern void InitBufferPoolBackend(void);
     184             : extern void AtEOXact_Buffers(bool isCommit);
     185             : extern void PrintBufferLeakWarning(Buffer buffer);
     186             : extern void CheckPointBuffers(int flags);
     187             : extern BlockNumber BufferGetBlockNumber(Buffer buffer);
     188             : extern BlockNumber RelationGetNumberOfBlocksInFork(Relation relation,
     189             :                                                    ForkNumber forkNum);
     190             : extern void FlushOneBuffer(Buffer buffer);
     191             : extern void FlushRelationBuffers(Relation rel);
     192             : extern void FlushDatabaseBuffers(Oid dbid);
     193             : extern void DropRelFileNodeBuffers(RelFileNodeBackend rnode, ForkNumber *forkNum,
     194             :                                    int nforks, BlockNumber *firstDelBlock);
     195             : extern void DropRelFileNodesAllBuffers(RelFileNodeBackend *rnodes, int nnodes);
     196             : extern void DropDatabaseBuffers(Oid dbid);
     197             : 
     198             : #define RelationGetNumberOfBlocks(reln) \
     199             :     RelationGetNumberOfBlocksInFork(reln, MAIN_FORKNUM)
     200             : 
     201             : extern bool BufferIsPermanent(Buffer buffer);
     202             : extern XLogRecPtr BufferGetLSNAtomic(Buffer buffer);
     203             : 
     204             : #ifdef NOT_USED
     205             : extern void PrintPinnedBufs(void);
     206             : #endif
     207             : extern Size BufferShmemSize(void);
     208             : extern void BufferGetTag(Buffer buffer, RelFileNode *rnode,
     209             :                          ForkNumber *forknum, BlockNumber *blknum);
     210             : 
     211             : extern void MarkBufferDirtyHint(Buffer buffer, bool buffer_std);
     212             : 
     213             : extern void UnlockBuffers(void);
     214             : extern void LockBuffer(Buffer buffer, int mode);
     215             : extern bool ConditionalLockBuffer(Buffer buffer);
     216             : extern void LockBufferForCleanup(Buffer buffer);
     217             : extern bool ConditionalLockBufferForCleanup(Buffer buffer);
     218             : extern bool IsBufferCleanupOK(Buffer buffer);
     219             : extern bool HoldingBufferPinThatDelaysRecovery(void);
     220             : 
     221             : extern void AbortBufferIO(void);
     222             : 
     223             : extern void BufmgrCommit(void);
     224             : extern bool BgBufferSync(struct WritebackContext *wb_context);
     225             : 
     226             : extern void AtProcExit_LocalBuffers(void);
     227             : 
     228             : extern void TestForOldSnapshot_impl(Snapshot snapshot, Relation relation);
     229             : 
     230             : /* in freelist.c */
     231             : extern BufferAccessStrategy GetAccessStrategy(BufferAccessStrategyType btype);
     232             : extern void FreeAccessStrategy(BufferAccessStrategy strategy);
     233             : 
     234             : 
     235             : /* inline functions */
     236             : 
     237             : /*
     238             :  * Although this header file is nominally backend-only, certain frontend
     239             :  * programs like pg_waldump include it.  For compilers that emit static
     240             :  * inline functions even when they're unused, that leads to unsatisfied
     241             :  * external references; hence hide these with #ifndef FRONTEND.
     242             :  */
     243             : 
     244             : #ifndef FRONTEND
     245             : 
     246             : /*
     247             :  * Check whether the given snapshot is too old to have safely read the given
     248             :  * page from the given table.  If so, throw a "snapshot too old" error.
     249             :  *
     250             :  * This test generally needs to be performed after every BufferGetPage() call
     251             :  * that is executed as part of a scan.  It is not needed for calls made for
     252             :  * modifying the page (for example, to position to the right place to insert a
     253             :  * new index tuple or for vacuuming).  It may also be omitted where calls to
     254             :  * lower-level functions will have already performed the test.
     255             :  *
     256             :  * Note that a NULL snapshot argument is allowed and causes a fast return
     257             :  * without error; this is to support call sites which can be called from
     258             :  * either scans or index modification areas.
     259             :  *
     260             :  * For best performance, keep the tests that are fastest and/or most likely to
     261             :  * exclude a page from old snapshot testing near the front.
     262             :  */
     263             : static inline void
     264   123745276 : TestForOldSnapshot(Snapshot snapshot, Relation relation, Page page)
     265             : {
     266             :     Assert(relation != NULL);
     267             : 
     268   123745276 :     if (old_snapshot_threshold >= 0
     269       60230 :         && (snapshot) != NULL
     270       58090 :         && ((snapshot)->snapshot_type == SNAPSHOT_MVCC
     271        2228 :             || (snapshot)->snapshot_type == SNAPSHOT_TOAST)
     272       55862 :         && !XLogRecPtrIsInvalid((snapshot)->lsn)
     273       55862 :         && PageGetLSN(page) > (snapshot)->lsn)
     274        6330 :         TestForOldSnapshot_impl(snapshot, relation);
     275   123745260 : }
     276             : 
     277             : #endif                          /* FRONTEND */
     278             : 
     279             : #endif                          /* BUFMGR_H */

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