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for already empty buffers because their buffer tag was not cleard out when the buffers have been invalidated before. Also removed the misnamed BM_FREE bufhdr flag and replaced the checks, which effectively ask if the buffer is unpinned, with checks against the refcount field. Jan
226 lines
6.4 KiB
C
226 lines
6.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* buf_internals.h
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* Internal definitions for buffer manager and the buffer replacement
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* strategy.
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*
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*
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* Portions Copyright (c) 1996-2003, 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/buf_internals.h,v 1.68 2004/02/12 15:06:56 wieck Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef BUFMGR_INTERNALS_H
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#define BUFMGR_INTERNALS_H
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#include "storage/backendid.h"
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#include "storage/buf.h"
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#include "storage/lmgr.h"
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#include "storage/lwlock.h"
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/* Buf Mgr constants */
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/* in bufmgr.c */
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extern int Data_Descriptors;
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extern int Free_List_Descriptor;
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extern int Lookup_List_Descriptor;
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extern int Num_Descriptors;
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extern int ShowPinTrace;
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/*
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* Flags for buffer descriptors
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*/
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#define BM_DIRTY (1 << 0)
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#define BM_VALID (1 << 1)
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#define BM_DELETED (1 << 2)
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#define BM_IO_IN_PROGRESS (1 << 3)
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#define BM_IO_ERROR (1 << 4)
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#define BM_JUST_DIRTIED (1 << 5)
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#define BM_PIN_COUNT_WAITER (1 << 6)
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typedef bits16 BufFlags;
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/*
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* Buffer tag identifies which disk block the buffer contains.
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*
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* Note: the BufferTag data must be sufficient to determine where to write the
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* block, even during a "blind write" with no relcache entry. It's possible
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* that the backend flushing the buffer doesn't even believe the relation is
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* visible yet (its xact may have started before the xact that created the
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* rel). The storage manager must be able to cope anyway.
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*/
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typedef struct buftag
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{
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RelFileNode rnode;
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BlockNumber blockNum; /* blknum relative to begin of reln */
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} BufferTag;
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#define CLEAR_BUFFERTAG(a) \
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( \
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(a)->rnode.tblNode = InvalidOid, \
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(a)->rnode.relNode = InvalidOid, \
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(a)->blockNum = InvalidBlockNumber \
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)
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#define INIT_BUFFERTAG(a,xx_reln,xx_blockNum) \
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( \
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(a)->blockNum = (xx_blockNum), \
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(a)->rnode = (xx_reln)->rd_node \
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)
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#define BUFFERTAG_EQUALS(a,xx_reln,xx_blockNum) \
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( \
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(a)->rnode.tblNode == (xx_reln)->rd_node.tblNode && \
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(a)->rnode.relNode == (xx_reln)->rd_node.relNode && \
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(a)->blockNum == (xx_blockNum) \
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)
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#define BUFFERTAGS_EQUAL(a,b) \
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( \
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(a)->rnode.tblNode == (b)->rnode.tblNode && \
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(a)->rnode.relNode == (b)->rnode.relNode && \
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(a)->blockNum == (b)->blockNum \
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)
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/*
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* BufferDesc -- shared buffer cache metadata for a single
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* shared buffer descriptor.
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*/
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typedef struct sbufdesc
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{
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Buffer bufNext; /* link in freelist chain */
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SHMEM_OFFSET data; /* pointer to data in buf pool */
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/* tag and id must be together for table lookup */
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BufferTag tag; /* file/block identifier */
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int buf_id; /* buffer's index number (from 0) */
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BufFlags flags; /* see bit definitions above */
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unsigned refcount; /* # of backends holding pins on buffer */
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LWLockId io_in_progress_lock; /* to wait for I/O to complete */
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LWLockId cntx_lock; /* to lock access to page context */
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bool cntxDirty; /* new way to mark block as dirty */
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/*
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* We can't physically remove items from a disk page if another
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* backend has the buffer pinned. Hence, a backend may need to wait
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* for all other pins to go away. This is signaled by setting its own
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* backend ID into wait_backend_id and setting flag bit
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* BM_PIN_COUNT_WAITER. At present, there can be only one such waiter
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* per buffer.
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*/
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BackendId wait_backend_id; /* backend ID of pin-count waiter */
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} BufferDesc;
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#define BufferDescriptorGetBuffer(bdesc) ((bdesc)->buf_id + 1)
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/*
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* Each backend has its own BufferLocks[] array holding flag bits
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* showing what locks it has set on each buffer.
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*
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* We have to free these locks during ereport(ERROR)...
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*/
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#define BL_IO_IN_PROGRESS (1 << 0) /* unimplemented */
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#define BL_PIN_COUNT_LOCK (1 << 1)
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/* entry for buffer hashtable */
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typedef struct
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{
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BufferTag key;
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Buffer id;
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} BufferLookupEnt;
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/*
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* Definitions for the buffer replacement strategy
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*/
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#define STRAT_LIST_UNUSED -1
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#define STRAT_LIST_B1 0
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#define STRAT_LIST_T1 1
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#define STRAT_LIST_T2 2
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#define STRAT_LIST_B2 3
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#define STRAT_NUM_LISTS 4
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/*
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* The Cache Directory Block (CDB) of the Adaptive Replacement Cache (ARC)
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*/
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typedef struct
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{
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int prev; /* links in the queue */
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int next;
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int list; /* current list */
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BufferTag buf_tag; /* buffer key */
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Buffer buf_id; /* currently assigned data buffer */
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TransactionId t1_xid; /* the xid this entry went onto T1 */
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} BufferStrategyCDB;
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/*
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* The shared ARC control information.
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*/
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typedef struct
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{
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int target_T1_size; /* What T1 size are we aiming for */
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int listUnusedCDB; /* All unused StrategyCDB */
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int listHead[STRAT_NUM_LISTS]; /* ARC lists B1, T1, T2 and B2 */
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int listTail[STRAT_NUM_LISTS];
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int listSize[STRAT_NUM_LISTS];
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Buffer listFreeBuffers; /* List of unused buffers */
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long num_lookup; /* Some hit statistics */
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long num_hit[STRAT_NUM_LISTS];
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time_t stat_report;
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BufferStrategyCDB cdb[1]; /* The cache directory */
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} BufferStrategyControl;
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/* counters in buf_init.c */
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extern long int ReadBufferCount;
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extern long int ReadLocalBufferCount;
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extern long int BufferHitCount;
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extern long int LocalBufferHitCount;
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extern long int BufferFlushCount;
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extern long int LocalBufferFlushCount;
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/*
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* Bufmgr Interface:
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*/
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/* Internal routines: only called by buf.c */
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/*freelist.c*/
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extern void PinBuffer(BufferDesc *buf);
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extern void UnpinBuffer(BufferDesc *buf);
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extern BufferDesc *StrategyBufferLookup(BufferTag *tagPtr, bool recheck);
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extern BufferDesc *StrategyGetBuffer(void);
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extern void StrategyReplaceBuffer(BufferDesc *buf, Relation rnode, BlockNumber blockNum);
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extern void StrategyInvalidateBuffer(BufferDesc *buf);
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extern void StrategyHintVacuum(bool vacuum_active);
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extern int StrategyDirtyBufferList(int *buffer_dirty, int max_buffers);
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extern void StrategyInitialize(bool init);
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/* buf_table.c */
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extern void InitBufTable(int size);
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extern int BufTableLookup(BufferTag *tagPtr);
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extern bool BufTableInsert(BufferTag *tagPtr, Buffer buf_id);
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extern bool BufTableDelete(BufferTag *tagPtr);
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/* bufmgr.c */
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extern BufferDesc *BufferDescriptors;
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extern bits8 *BufferLocks;
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/* localbuf.c */
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extern BufferDesc *LocalBufferDescriptors;
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extern BufferDesc *LocalBufferAlloc(Relation reln, BlockNumber blockNum,
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bool *foundPtr);
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extern void WriteLocalBuffer(Buffer buffer, bool release);
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extern void AtEOXact_LocalBuffers(bool isCommit);
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#endif /* BUFMGR_INTERNALS_H */
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