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If a standby is broadcasting reply messages and we have named one or more standbys in synchronous_standby_names then allow users who set synchronous_replication to wait for commit, which then provides strict data integrity guarantees. Design avoids sending and receiving transaction state information so minimises bookkeeping overheads. We synchronize with the highest priority standby that is connected and ready to synchronize. Other standbys can be defined to takeover in case of standby failure. This version has very strict behaviour; more relaxed options may be added at a later date. Simon Riggs and Fujii Masao, with reviews by Yeb Havinga, Jaime Casanova, Heikki Linnakangas and Robert Haas, plus the assistance of many other design reviewers.
119 lines
3.3 KiB
C
119 lines
3.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* lwlock.h
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* Lightweight lock manager
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*
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*
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* Portions Copyright (c) 1996-2011, 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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* src/include/storage/lwlock.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef LWLOCK_H
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#define LWLOCK_H
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/*
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* It's a bit odd to declare NUM_BUFFER_PARTITIONS and NUM_LOCK_PARTITIONS
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* here, but we need them to set up enum LWLockId correctly, and having
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* this file include lock.h or bufmgr.h would be backwards.
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*/
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/* Number of partitions of the shared buffer mapping hashtable */
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#define NUM_BUFFER_PARTITIONS 16
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/* Number of partitions the shared lock tables are divided into */
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#define LOG2_NUM_LOCK_PARTITIONS 4
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#define NUM_LOCK_PARTITIONS (1 << LOG2_NUM_LOCK_PARTITIONS)
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/* Number of partitions the shared predicate lock tables are divided into */
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#define LOG2_NUM_PREDICATELOCK_PARTITIONS 4
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#define NUM_PREDICATELOCK_PARTITIONS (1 << LOG2_NUM_PREDICATELOCK_PARTITIONS)
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/*
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* We have a number of predefined LWLocks, plus a bunch of LWLocks that are
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* dynamically assigned (e.g., for shared buffers). The LWLock structures
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* live in shared memory (since they contain shared data) and are identified
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* by values of this enumerated type. We abuse the notion of an enum somewhat
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* by allowing values not listed in the enum declaration to be assigned.
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* The extra value MaxDynamicLWLock is there to keep the compiler from
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* deciding that the enum can be represented as char or short ...
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*
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* If you remove a lock, please replace it with a placeholder. This retains
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* the lock numbering, which is helpful for DTrace and other external
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* debugging scripts.
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*/
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typedef enum LWLockId
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{
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BufFreelistLock,
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ShmemIndexLock,
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OidGenLock,
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XidGenLock,
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ProcArrayLock,
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SInvalReadLock,
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SInvalWriteLock,
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WALInsertLock,
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WALWriteLock,
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ControlFileLock,
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CheckpointLock,
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CLogControlLock,
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SubtransControlLock,
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MultiXactGenLock,
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MultiXactOffsetControlLock,
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MultiXactMemberControlLock,
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RelCacheInitLock,
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BgWriterCommLock,
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TwoPhaseStateLock,
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TablespaceCreateLock,
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BtreeVacuumLock,
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AddinShmemInitLock,
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AutovacuumLock,
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AutovacuumScheduleLock,
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SyncScanLock,
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RelationMappingLock,
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AsyncCtlLock,
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AsyncQueueLock,
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SerializableXactHashLock,
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SerializableFinishedListLock,
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SerializablePredicateLockListLock,
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OldSerXidLock,
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SyncRepLock,
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/* Individual lock IDs end here */
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FirstBufMappingLock,
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FirstLockMgrLock = FirstBufMappingLock + NUM_BUFFER_PARTITIONS,
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FirstPredicateLockMgrLock = FirstLockMgrLock + NUM_LOCK_PARTITIONS,
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/* must be last except for MaxDynamicLWLock: */
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NumFixedLWLocks = FirstPredicateLockMgrLock + NUM_PREDICATELOCK_PARTITIONS,
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MaxDynamicLWLock = 1000000000
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} LWLockId;
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typedef enum LWLockMode
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{
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LW_EXCLUSIVE,
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LW_SHARED
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} LWLockMode;
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#ifdef LOCK_DEBUG
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extern bool Trace_lwlocks;
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#endif
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extern LWLockId LWLockAssign(void);
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extern void LWLockAcquire(LWLockId lockid, LWLockMode mode);
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extern bool LWLockConditionalAcquire(LWLockId lockid, LWLockMode mode);
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extern void LWLockRelease(LWLockId lockid);
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extern void LWLockReleaseAll(void);
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extern bool LWLockHeldByMe(LWLockId lockid);
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extern int NumLWLocks(void);
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extern Size LWLockShmemSize(void);
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extern void CreateLWLocks(void);
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extern void RequestAddinLWLocks(int n);
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#endif /* LWLOCK_H */
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