sync.h

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/*-------------------------------------------------------------------------
 *
 * sync.h
 *    File synchronization management code.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/storage/sync.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef SYNC_H
#define SYNC_H
 
#include "storage/relfilelocator.h"
 
/*
 * Type of sync request.  These are used to manage the set of pending
 * requests to call a sync handler's sync or unlink functions at the next
 * checkpoint.
 */
typedef enum SyncRequestType
{
    SYNC_REQUEST,               /* schedule a call of sync function */
    SYNC_UNLINK_REQUEST,        /* schedule a call of unlink function */
    SYNC_FORGET_REQUEST,        /* forget all calls for a tag */
    SYNC_FILTER_REQUEST,        /* forget all calls satisfying match fn */
} SyncRequestType;
 
/*
 * Which set of functions to use to handle a given request.  The values of
 * the enumerators must match the indexes of the function table in sync.c.
 */
typedef enum SyncRequestHandler
{
    SYNC_HANDLER_MD = 0,
    SYNC_HANDLER_CLOG,
    SYNC_HANDLER_COMMIT_TS,
    SYNC_HANDLER_MULTIXACT_OFFSET,
    SYNC_HANDLER_MULTIXACT_MEMBER,
    SYNC_HANDLER_NONE,
} SyncRequestHandler;
 
/*
 * A tag identifying a file.  Currently it has the members required for md.c's
 * usage, but sync.c has no knowledge of the internal structure, and it is
 * liable to change as required by future handlers.
 */
typedef struct FileTag
{
    int16       handler;        /* SyncRequestHandler value, saving space */
    int16       forknum;        /* ForkNumber, saving space */
    RelFileLocator rlocator;
    uint64      segno;
} FileTag;
 
extern void InitSync(void);
extern void SyncPreCheckpoint(void);
extern void SyncPostCheckpoint(void);
extern void ProcessSyncRequests(void);
extern void RememberSyncRequest(const FileTag *ftag, SyncRequestType type);
extern bool RegisterSyncRequest(const FileTag *ftag, SyncRequestType type,
                                bool retryOnError);
 
#endif                          /* SYNC_H */