standbydefs.h

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/*-------------------------------------------------------------------------
 *
 * standbydefs.h
 *     Frontend exposed definitions for hot standby mode.
 *
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/storage/standbydefs.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef STANDBYDEFS_H
#define STANDBYDEFS_H
 
#include "access/xlogreader.h"
#include "lib/stringinfo.h"
#include "storage/lockdefs.h"
#include "storage/sinval.h"
 
/* Recovery handlers for the Standby Rmgr (RM_STANDBY_ID) */
extern void standby_redo(XLogReaderState *record);
extern void standby_desc(StringInfo buf, XLogReaderState *record);
extern const char *standby_identify(uint8 info);
extern void standby_desc_invalidations(StringInfo buf,
                                       int nmsgs, SharedInvalidationMessage *msgs,
                                       Oid dbId, Oid tsId,
                                       bool relcacheInitFileInval);
 
/*
 * XLOG message types
 */
#define XLOG_STANDBY_LOCK           0x00
#define XLOG_RUNNING_XACTS          0x10
#define XLOG_INVALIDATIONS          0x20
 
typedef struct xl_standby_locks
{
    int         nlocks;         /* number of entries in locks array */
    xl_standby_lock locks[FLEXIBLE_ARRAY_MEMBER];
} xl_standby_locks;
 
/*
 * When we write running xact data to WAL, we use this structure.
 */
typedef struct xl_running_xacts
{
    int         xcnt;           /* # of xact ids in xids[] */
    int         subxcnt;        /* # of subxact ids in xids[] */
    bool        subxid_overflow;    /* snapshot overflowed, subxids missing */
    TransactionId nextXid;      /* xid from TransamVariables->nextXid */
    TransactionId oldestRunningXid; /* *not* oldestXmin */
    TransactionId latestCompletedXid;   /* so we can set xmax */
 
    TransactionId xids[FLEXIBLE_ARRAY_MEMBER];
} xl_running_xacts;
 
/*
 * Invalidations for standby, currently only when transactions without an
 * assigned xid commit.
 */
typedef struct xl_invalidations
{
    Oid         dbId;           /* MyDatabaseId */
    Oid         tsId;           /* MyDatabaseTableSpace */
    bool        relcacheInitFileInval;  /* invalidate relcache init files */
    int         nmsgs;          /* number of shared inval msgs */
    SharedInvalidationMessage msgs[FLEXIBLE_ARRAY_MEMBER];
} xl_invalidations;
 
#define MinSizeOfInvalidations offsetof(xl_invalidations, msgs)
 
#endif                          /* STANDBYDEFS_H */