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pg_include/storage/standby.h

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+/*-------------------------------------------------------------------------
+ *
+ * standby.h
+ *	  Definitions for hot standby mode.
+ *
+ *
+ * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/standby.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef STANDBY_H
+#define STANDBY_H
+
+#include "access/xlog.h"
+#include "storage/lock.h"
+#include "storage/procsignal.h"
+#include "storage/relfilenode.h"
+
+/* User-settable GUC parameters */
+extern int	vacuum_defer_cleanup_age;
+extern int	max_standby_archive_delay;
+extern int	max_standby_streaming_delay;
+
+extern void InitRecoveryTransactionEnvironment(void);
+extern void ShutdownRecoveryTransactionEnvironment(void);
+
+extern void ResolveRecoveryConflictWithSnapshot(TransactionId latestRemovedXid,
+									RelFileNode node);
+extern void ResolveRecoveryConflictWithTablespace(Oid tsid);
+extern void ResolveRecoveryConflictWithDatabase(Oid dbid);
+
+extern void ResolveRecoveryConflictWithBufferPin(void);
+extern void SendRecoveryConflictWithBufferPin(ProcSignalReason reason);
+extern void CheckRecoveryConflictDeadlock(void);
+
+/*
+ * Standby Rmgr (RM_STANDBY_ID)
+ *
+ * Standby recovery manager exists to perform actions that are required
+ * to make hot standby work. That includes logging AccessExclusiveLocks taken
+ * by transactions and running-xacts snapshots.
+ */
+extern void StandbyAcquireAccessExclusiveLock(TransactionId xid, Oid dbOid, Oid relOid);
+extern void StandbyReleaseLockTree(TransactionId xid,
+					   int nsubxids, TransactionId *subxids);
+extern void StandbyReleaseAllLocks(void);
+extern void StandbyReleaseOldLocks(int nxids, TransactionId *xids);
+
+/*
+ * XLOG message types
+ */
+#define XLOG_STANDBY_LOCK			0x00
+#define XLOG_RUNNING_XACTS			0x10
+
+typedef struct xl_standby_locks
+{
+	int			nlocks;			/* number of entries in locks array */
+	xl_standby_lock locks[1];	/* VARIABLE LENGTH ARRAY */
+} 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[] */
+	bool		subxid_overflow;	/* snapshot overflowed, subxids missing */
+	TransactionId nextXid;		/* copy of ShmemVariableCache->nextXid */
+	TransactionId oldestRunningXid;		/* *not* oldestXmin */
+	TransactionId latestCompletedXid;	/* so we can set xmax */
+
+	TransactionId xids[1];		/* VARIABLE LENGTH ARRAY */
+} xl_running_xacts;
+
+#define MinSizeOfXactRunningXacts offsetof(xl_running_xacts, xids)
+
+
+/* Recovery handlers for the Standby Rmgr (RM_STANDBY_ID) */
+extern void standby_redo(XLogRecPtr lsn, XLogRecord *record);
+extern void standby_desc(StringInfo buf, uint8 xl_info, char *rec);
+
+/*
+ * Declarations for GetRunningTransactionData(). Similar to Snapshots, but
+ * not quite. This has nothing at all to do with visibility on this server,
+ * so this is completely separate from snapmgr.c and snapmgr.h.
+ * This data is important for creating the initial snapshot state on a
+ * standby server. We need lots more information than a normal snapshot,
+ * hence we use a specific data structure for our needs. This data
+ * is written to WAL as a separate record immediately after each
+ * checkpoint. That means that wherever we start a standby from we will
+ * almost immediately see the data we need to begin executing queries.
+ */
+
+typedef struct RunningTransactionsData
+{
+	int			xcnt;			/* # of xact ids in xids[] */
+	bool		subxid_overflow;	/* snapshot overflowed, subxids missing */
+	TransactionId nextXid;		/* copy of ShmemVariableCache->nextXid */
+	TransactionId oldestRunningXid;		/* *not* oldestXmin */
+	TransactionId latestCompletedXid;	/* so we can set xmax */
+
+	TransactionId *xids;		/* array of (sub)xids still running */
+} RunningTransactionsData;
+
+typedef RunningTransactionsData *RunningTransactions;
+
+extern void LogAccessExclusiveLock(Oid dbOid, Oid relOid);
+extern void LogAccessExclusiveLockPrepare(void);
+
+extern void LogStandbySnapshot(void);
+
+#endif   /* STANDBY_H */