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63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
/*
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* slru.h
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*
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* Simple LRU
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*
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* Portions Copyright (c) 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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* $Id: slru.h,v 1.2 2003/08/04 00:43:30 momjian Exp $
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*/
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#ifndef SLRU_H
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#define SLRU_H
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#include "access/xlog.h"
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/* exported because lwlock.c needs it */
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#define NUM_CLOG_BUFFERS 8
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typedef struct SlruLockData
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{
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LWLockId ControlLock;
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/*
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* BufferLocks is set during CLOGShmemInit and does not change thereafter.
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* The value is automatically inherited by backends via fork, and
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* doesn't need to be in shared memory.
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*/
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LWLockId BufferLocks[NUM_CLOG_BUFFERS]; /* Per-buffer I/O locks */
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} SlruLockData;
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typedef SlruLockData *SlruLock;
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typedef struct SlruCtlData
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{
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void *shared; /* pointer to SlruSharedData */
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SlruLock locks;
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/*
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* Dir is set during SimpleLruShmemInit and does not change thereafter.
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* The value is automatically inherited by backends via fork, and
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* doesn't need to be in shared memory.
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*/
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char Dir[MAXPGPATH];
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/*
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* Decide which of two page numbers is "older" for truncation purposes.
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* We need to use comparison of TransactionIds here in order to do the right
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* thing with wraparound XID arithmetic.
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*/
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bool (*PagePrecedes) (int, int);
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} SlruCtlData;
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typedef SlruCtlData *SlruCtl;
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extern int SimpleLruShmemSize(void);
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extern void SimpleLruInit(SlruCtl ctl, const char *name, const char *subdir);
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extern int SimpleLruZeroPage(SlruCtl ctl, int pageno);
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extern char *SimpleLruReadPage(SlruCtl ctl, int pageno, TransactionId xid, bool forwrite);
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extern void SimpleLruWritePage(SlruCtl ctl, int slotno);
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extern void SimpleLruSetLatestPage(SlruCtl ctl, int pageno);
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extern void SimpleLruFlush(SlruCtl ctl, bool checkpoint);
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extern void SimpleLruTruncate(SlruCtl ctl, int cutoffPage);
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#endif /* SLRU_H */
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