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/*
* slru.h
*
* Simple LRU
*
* Portions Copyright (c) 2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/slru.h,v 1.7 2004/07/01 00:51:38 tgl Exp $
*/
#ifndef SLRU_H
#define SLRU_H
#include "access/xlog.h"
#include "storage/lwlock.h"
/* Opaque structs known only in slru.c */
typedef struct SlruSharedData *SlruShared;
typedef struct SlruFlushData *SlruFlush;
/*
* SlruCtlData is an unshared structure that points to the active information
* in shared memory.
*/
typedef struct SlruCtlData
{
SlruShared shared;
LWLockId ControlLock;
/*
* Dir is set during SimpleLruInit and does not change thereafter.
* Since it's always the same, it doesn't need to be in shared memory.
*/
char Dir[MAXPGPATH];
/*
* Decide which of two page numbers is "older" for truncation purposes.
* We need to use comparison of TransactionIds here in order to do the
* right thing with wraparound XID arithmetic.
*/
bool (*PagePrecedes) (int, int);
} SlruCtlData;
typedef SlruCtlData *SlruCtl;
extern int SimpleLruShmemSize(void);
extern void SimpleLruInit(SlruCtl ctl, const char *name, const char *subdir);
extern int SimpleLruZeroPage(SlruCtl ctl, int pageno);
extern char *SimpleLruReadPage(SlruCtl ctl, int pageno,
TransactionId xid, bool forwrite);
extern void SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata);
extern void SimpleLruSetLatestPage(SlruCtl ctl, int pageno);
extern void SimpleLruFlush(SlruCtl ctl, bool checkpoint);
extern void SimpleLruTruncate(SlruCtl ctl, int cutoffPage);
/* XLOG stuff */
#define CLOG_ZEROPAGE 0x00
#define SUBTRANS_ZEROPAGE 0x10
extern void slru_redo(XLogRecPtr lsn, XLogRecord *record);
extern void slru_undo(XLogRecPtr lsn, XLogRecord *record);
extern void slru_desc(char *buf, uint8 xl_info, char *rec);
#endif /* SLRU_H */
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