diff options
Diffstat (limited to 'src/include/storage/lock.h')
| -rw-r--r-- | src/include/storage/lock.h | 42 |
1 files changed, 28 insertions, 14 deletions
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h index d471293b702..7a2651cd28f 100644 --- a/src/include/storage/lock.h +++ b/src/include/storage/lock.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.95 2006/07/23 03:07:58 tgl Exp $ + * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.96 2006/07/23 23:08:46 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -266,7 +266,9 @@ typedef struct LOCK * * PROCLOCKTAG is the key information needed to look up a PROCLOCK item in the * proclock hashtable. A PROCLOCKTAG value uniquely identifies the combination - * of a lockable object and a holder/waiter for that object. + * of a lockable object and a holder/waiter for that object. (We can use + * pointers here because the PROCLOCKTAG need only be unique for the lifespan + * of the PROCLOCK, and it will never outlive the lock or the proc.) * * Internally to a backend, it is possible for the same lock to be held * for different purposes: the backend tracks transaction locks separately @@ -292,8 +294,9 @@ typedef struct LOCK */ typedef struct PROCLOCKTAG { - SHMEM_OFFSET lock; /* link to per-lockable-object information */ - SHMEM_OFFSET proc; /* link to PGPROC of owning backend */ + /* NB: we assume this struct contains no padding! */ + LOCK *myLock; /* link to per-lockable-object information */ + PGPROC *myProc; /* link to PGPROC of owning backend */ } PROCLOCKTAG; typedef struct PROCLOCK @@ -309,7 +312,7 @@ typedef struct PROCLOCK } PROCLOCK; #define PROCLOCK_LOCKMETHOD(proclock) \ - LOCK_LOCKMETHOD(*((LOCK *) MAKE_PTR((proclock).tag.lock))) + LOCK_LOCKMETHOD(*((proclock).tag.myLock)) /* * Each backend also maintains a local hash table with information about each @@ -347,7 +350,7 @@ typedef struct LOCALLOCK LOCK *lock; /* associated LOCK object in shared mem */ PROCLOCK *proclock; /* associated PROCLOCK object in shmem */ bool isTempObject; /* true if lock is on a temporary object */ - int partition; /* ID of partition containing this lock */ + uint32 hashcode; /* copy of LOCKTAG's hash value */ int nLocks; /* total number of times lock is held */ int numLockOwners; /* # of relevant ResourceOwners */ int maxLockOwners; /* allocated size of array */ @@ -360,15 +363,14 @@ typedef struct LOCALLOCK /* * This struct holds information passed from lmgr internals to the lock * listing user-level functions (lockfuncs.c). For each PROCLOCK in the - * system, the SHMEM_OFFSET, PROCLOCK itself, and associated PGPROC and - * LOCK objects are stored. (Note there will often be multiple copies - * of the same PGPROC or LOCK.) We do not store the SHMEM_OFFSET of the - * PGPROC or LOCK separately, since they're in the PROCLOCK's tag fields. + * system, copies of the PROCLOCK object and associated PGPROC and + * LOCK objects are stored. Note there will often be multiple copies + * of the same PGPROC or LOCK --- to detect whether two are the same, + * compare the PROCLOCK tag fields. */ -typedef struct +typedef struct LockData { int nelements; /* The length of each of the arrays */ - SHMEM_OFFSET *proclockaddrs; PROCLOCK *proclocks; PGPROC *procs; LOCK *locks; @@ -385,11 +387,23 @@ typedef enum /* + * The lockmgr's shared hash tables are partitioned to reduce contention. + * To determine which partition a given locktag belongs to, compute the tag's + * hash code with LockTagHashCode(), then apply one of these macros. + * NB: NUM_LOCK_PARTITIONS must be a power of 2! + */ +#define LockHashPartition(hashcode) \ + ((hashcode) % NUM_LOCK_PARTITIONS) +#define LockHashPartitionLock(hashcode) \ + ((LWLockId) (FirstLockMgrLock + LockHashPartition(hashcode))) + + +/* * function prototypes */ extern void InitLocks(void); extern LockMethod GetLocksMethodTable(const LOCK *lock); -extern int LockTagToPartition(const LOCKTAG *locktag); +extern uint32 LockTagHashCode(const LOCKTAG *locktag); extern LockAcquireResult LockAcquire(const LOCKTAG *locktag, bool isTempObject, LOCKMODE lockmode, @@ -407,7 +421,7 @@ extern int LockCheckConflicts(LockMethod lockMethodTable, LOCK *lock, PROCLOCK *proclock, PGPROC *proc); extern void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode); extern void GrantAwaitedLock(void); -extern void RemoveFromWaitQueue(PGPROC *proc, int partition); +extern void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode); extern Size LockShmemSize(void); extern bool DeadLockCheck(PGPROC *proc); extern void DeadLockReport(void); |