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More cleanups of the include files
- centralizing to simplify the -I's required to compile
This commit is contained in:
Marc G. Fournier
218
src/include/storage/lock.h
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218
src/include/storage/lock.h
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/*-------------------------------------------------------------------------
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*
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* lock.h--
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*
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*
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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* $Id: lock.h,v 1.1 1996/08/28 01:58:15 scrappy Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef LOCK_H_
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#define LOCK_H_
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#include "postgres.h"
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#include "storage/itemptr.h"
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#include "storage/shmem.h"
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#include "storage/spin.h"
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#include "storage/backendid.h"
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#include "utils/hsearch.h"
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extern SPINLOCK LockMgrLock;
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typedef int MASK;
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#define INIT_TABLE_SIZE 100
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#define MAX_TABLE_SIZE 1000
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/* ----------------------
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* The following defines are used to estimate how much shared
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* memory the lock manager is going to require.
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*
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* NBACKENDS - The number of concurrently running backends
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* NLOCKS_PER_XACT - The number of unique locks acquired in a transaction
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* NLOCKENTS - The maximum number of lock entries in the lock table.
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* ----------------------
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*/
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#define NBACKENDS 50
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#define NLOCKS_PER_XACT 40
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#define NLOCKENTS NLOCKS_PER_XACT*NBACKENDS
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typedef int LOCK_TYPE;
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typedef int LOCKT;
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typedef int LockTableId;
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/* MAX_LOCKTYPES cannot be larger than the bits in MASK */
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#define MAX_LOCKTYPES 6
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/*
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* MAX_TABLES corresponds to the number of spin locks allocated in
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* CreateSpinLocks() or the number of shared memory locations allocated
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* for lock table spin locks in the case of machines with TAS instructions.
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*/
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#define MAX_TABLES 2
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#define INVALID_TABLEID 0
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/*typedef struct LOCK LOCK; */
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typedef struct ltag {
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Oid relId;
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Oid dbId;
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ItemPointerData tupleId;
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} LOCKTAG;
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#define TAGSIZE (sizeof(LOCKTAG))
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/* This is the control structure for a lock table. It
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* lives in shared memory:
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*
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* tableID -- the handle used by the lock table's clients to
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* refer to the table.
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*
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* nLockTypes -- number of lock types (READ,WRITE,etc) that
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* are defined on this lock table
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*
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* conflictTab -- this is an array of bitmasks showing lock
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* type conflicts. conflictTab[i] is a mask with the j-th bit
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* turned on if lock types i and j conflict.
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*
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* prio -- each locktype has a priority, so, for example, waiting
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* writers can be given priority over readers (to avoid
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* starvation).
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*
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* masterlock -- synchronizes access to the table
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*
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*/
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typedef struct lockctl {
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LockTableId tableId;
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int nLockTypes;
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int conflictTab[MAX_LOCKTYPES];
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int prio[MAX_LOCKTYPES];
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SPINLOCK masterLock;
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} LOCKCTL;
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/*
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* lockHash -- hash table on lock Ids,
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* xidHash -- hash on xid and lockId in case
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* multiple processes are holding the lock
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* ctl - control structure described above.
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*/
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typedef struct ltable {
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HTAB *lockHash;
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HTAB *xidHash;
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LOCKCTL *ctl;
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} LOCKTAB;
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/* -----------------------
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* A transaction never conflicts with its own locks. Hence, if
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* multiple transactions hold non-conflicting locks on the same
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* data, private per-transaction information must be stored in the
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* XID table. The tag is XID + shared memory lock address so that
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* all locks can use the same XID table. The private information
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* we store is the number of locks of each type (holders) and the
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* total number of locks (nHolding) held by the transaction.
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*
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* NOTE: --
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* There were some problems with the fact that currently TransactionIdData
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* is a 5 byte entity and compilers long word aligning of structure fields.
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* If the 3 byte padding is put in front of the actual xid data then the
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* hash function (which uses XID_TAGSIZE when deciding how many bytes of a
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* struct to look at for the key) might only see the last two bytes of the xid.
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*
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* Clearly this is not good since its likely that these bytes will be the
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* same for many transactions and hence they will share the same entry in
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* hash table causing the entry to be corrupted. For this long-winded
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* reason I have put the tag in a struct of its own to ensure that the
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* XID_TAGSIZE is computed correctly. It used to be sizeof (SHMEM_OFFSET) +
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* sizeof(TransactionIdData) which != sizeof(XIDTAG).
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*
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* Finally since the hash function will now look at all 12 bytes of the tag
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* the padding bytes MUST be zero'd before use in hash_search() as they
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* will have random values otherwise. Jeff 22 July 1991.
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* -----------------------
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*/
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typedef struct XIDTAG {
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SHMEM_OFFSET lock;
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int pid;
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TransactionId xid;
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} XIDTAG;
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typedef struct XIDLookupEnt {
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/* tag */
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XIDTAG tag;
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/* data */
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int holders[MAX_LOCKTYPES];
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int nHolding;
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SHM_QUEUE queue;
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} XIDLookupEnt;
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#define XID_TAGSIZE (sizeof(XIDTAG))
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/* originally in procq.h */
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typedef struct procQueue {
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SHM_QUEUE links;
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int size;
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} PROC_QUEUE;
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/*
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* lock information:
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*
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* tag -- uniquely identifies the object being locked
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* mask -- union of the conflict masks of all lock types
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* currently held on this object.
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* waitProcs -- queue of processes waiting for this lock
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* holders -- count of each lock type currently held on the
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* lock.
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* nHolding -- total locks of all types.
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*/
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typedef struct Lock {
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/* hash key */
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LOCKTAG tag;
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/* data */
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int mask;
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PROC_QUEUE waitProcs;
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int holders[MAX_LOCKTYPES];
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int nHolding;
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int activeHolders[MAX_LOCKTYPES];
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int nActive;
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} LOCK;
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#define LockGetLock_nHolders(l) l->nHolders
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#define LockDecrWaitHolders(lock, lockt) \
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lock->nHolding--; \
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lock->holders[lockt]--
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#define LockLockTable() SpinAcquire(LockMgrLock);
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#define UnlockLockTable() SpinRelease(LockMgrLock);
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extern SPINLOCK LockMgrLock;
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/*
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* function prototypes
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*/
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extern void InitLocks(void);
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extern void LockDisable(int status);
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extern LockTableId LockTabInit(char *tabName, MASK *conflictsP, int *prioP,
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int ntypes);
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extern LockTableId LockTabRename(LockTableId tableId);
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extern bool LockAcquire(LockTableId tableId, LOCKTAG *lockName, LOCKT lockt);
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extern int LockResolveConflicts(LOCKTAB *ltable, LOCK *lock, LOCKT lockt,
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TransactionId xid);
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extern int WaitOnLock(LOCKTAB *ltable, LockTableId tableId, LOCK *lock,
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LOCKT lockt);
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extern bool LockRelease(LockTableId tableId, LOCKTAG *lockName, LOCKT lockt);
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extern void GrantLock(LOCK *lock, LOCKT lockt);
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extern bool LockReleaseAll(LockTableId tableId, SHM_QUEUE *lockQueue);
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extern int LockShmemSize(void);
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extern bool LockingDisabled(void);
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#endif /* LOCK_H */
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