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246 lines
8.6 KiB
246 lines
8.6 KiB
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996, 1997, 1998, 1999
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* Sleepycat Software. All rights reserved.
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*
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* @(#)lock.h 11.5 (Sleepycat) 10/27/99
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*/
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#ifndef DB_LOCK_DEFAULT_N
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#define DB_LOCK_DEFAULT_N 1000 /* Default # of locks in region. */
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#endif
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/*
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* Out of band value for a lock. Locks contain an offset into a lock region,
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* so we use an invalid region offset to indicate an invalid or unset lock.
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*/
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#define LOCK_INVALID INVALID_ROFF
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/*
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* The locker id space is divided between the transaction manager and the lock
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* manager. Lock IDs start at 0 and go to DB_LOCK_MAXID. Txn IDs start at
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* DB_LOCK_MAXID + 1 and go up to TXN_INVALID.
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*/
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#define DB_LOCK_MAXID 0x7fffffff
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/*
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* DB_LOCKREGION --
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* The lock shared region.
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*/
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typedef struct __db_lockregion {
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u_int32_t id; /* unique id generator */
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u_int32_t need_dd; /* flag for deadlock detector */
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u_int32_t detect; /* run dd on every conflict */
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/* free lock header */
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SH_TAILQ_HEAD(__flock) free_locks;
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/* free obj header */
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SH_TAILQ_HEAD(__fobj) free_objs;
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/* free locker header */
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SH_TAILQ_HEAD(__flocker) free_lockers;
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u_int32_t maxlocks; /* maximum number of locks in table */
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u_int32_t table_size; /* size of hash table */
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u_int32_t nmodes; /* number of lock modes */
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u_int32_t nlockers; /* number of lockers */
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u_int32_t maxnlockers; /* maximum number of lockers */
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roff_t memlock_off; /* offset of memory mutex */
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roff_t conf_off; /* offset of conflicts array */
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roff_t obj_off; /* offset of object hash table */
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roff_t osynch_off; /* offset of the object mutex table */
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roff_t locker_off; /* offset of locker hash table */
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roff_t lsynch_off; /* offset of the locker mutex table */
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u_int32_t nconflicts; /* number of lock conflicts */
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u_int32_t nrequests; /* number of lock gets */
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u_int32_t nreleases; /* number of lock puts */
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u_int32_t ndeadlocks; /* number of deadlocks */
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} DB_LOCKREGION;
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/*
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* Since we will store DBTs in shared memory, we need the equivalent of a
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* DBT that will work in shared memory.
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*/
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typedef struct __sh_dbt {
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u_int32_t size; /* Byte length. */
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ssize_t off; /* Region offset. */
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} SH_DBT;
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#define SH_DBT_PTR(p) ((void *)(((u_int8_t *)(p)) + (p)->off))
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/*
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* Object structures; these live in the object hash table.
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*/
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typedef struct __db_lockobj {
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SH_DBT lockobj; /* Identifies object locked. */
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SH_TAILQ_ENTRY links; /* Links for free list. */
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SH_TAILQ_HEAD(__wait) waiters; /* List of waiting locks. */
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SH_TAILQ_HEAD(__hold) holders; /* List of held locks. */
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/* Declare room in the object to hold
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* typical DB lock structures so that
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* we do not have to allocate them from
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* shalloc at run-time. */
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u_int8_t objdata[sizeof(struct __db_ilock)];
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} DB_LOCKOBJ;
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/*
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* Locker structures; these live in the locker hash table.
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*/
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typedef struct __db_locker {
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u_int32_t id; /* Locker id. */
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u_int32_t dd_id; /* Deadlock detector id. */
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size_t master_locker; /* Locker of master transaction. */
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size_t parent_locker; /* Parent of this child. */
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SH_LIST_HEAD(_child) child_locker; /* List of descendant txns;
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only used in a "master"
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txn. */
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SH_LIST_ENTRY child_link; /* Links transactions in the family;
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elements of the child_locker
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list. */
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SH_TAILQ_ENTRY links; /* Links for free list. */
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SH_LIST_HEAD(_held) heldby; /* Locks held by this locker. */
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#define DB_LOCKER_DELETED 0x0001
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u_int32_t flags;
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} DB_LOCKER;
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/*
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* Lockers can be freed if they are not poart of a transaction
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* family. Members of a family either point at the master
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* transaction or are the master transaction and have
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* children lockers.
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*/
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#define LOCKER_FREEABLE(lp) ((lp)->master_locker \
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== TXN_INVALID_ID && \
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SH_LIST_FIRST(&(lp)->child_locker, __db_locker) \
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== NULL)
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/*
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* DB_LOCKTAB --
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* The primary library lock data structure (i.e., the one referenced
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* by the environment, as opposed to the internal one laid out in the region.)
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*/
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typedef struct __db_locktab {
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DB_ENV *dbenv; /* Environment. */
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REGINFO reginfo; /* Region information. */
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MUTEX *memlock; /* Mutex to protect memory alloc. */
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u_int8_t *conflicts; /* Pointer to conflict matrix. */
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DB_HASHTAB *obj_tab; /* Beginning of object hash table. */
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MUTEX *osynch_tab; /* Object mutex table. */
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DB_HASHTAB *locker_tab; /* Beginning of locker hash table. */
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MUTEX *lsynch_tab; /* Locker mutex table. */
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} DB_LOCKTAB;
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/* Test for conflicts. */
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#define CONFLICTS(T, R, HELD, WANTED) \
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(T)->conflicts[(HELD) * (R)->nmodes + (WANTED)]
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#define OBJ_LINKS_VALID(L) ((L)->links.stqe_prev != -1)
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struct __db_lock {
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/*
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* Wait on mutex to wait on lock. You reference your own mutex with
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* ID 0 and others reference your mutex with ID 1.
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*/
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MUTEX mutex;
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u_int32_t holder; /* Who holds this lock. */
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u_int32_t gen; /* Generation count. */
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SH_TAILQ_ENTRY links; /* Free or holder/waiter list. */
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SH_LIST_ENTRY locker_links; /* List of locks held by a locker. */
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u_int32_t refcount; /* Reference count the lock. */
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db_lockmode_t mode; /* What sort of lock. */
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ssize_t obj; /* Relative offset of object struct. */
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roff_t txnoff; /* Offset of holding transaction. */
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db_status_t status; /* Status of this lock. */
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};
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/*
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* This is a serious layering violation. To support nested transactions, we
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* need to be able to tell that a lock is held by a transaction (as opposed to
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* some other locker) and to be able to traverse the parent/descendent chain.
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* In order to do this, each lock held by a transaction maintains a reference
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* to the shared memory transaction structure so it can be accessed during lock
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* promotion. As the structure is in shared memory, we cannot store a pointer
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* to it, so we use the offset within the region. An invalid region offset is
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* used to indicate that there is no transaction associated with the current
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* lock.
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*/
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#define TXN_IS_HOLDING(L) ((L)->txnoff != INVALID_ROFF)
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/*
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* Flag values for CDB___lock_put_internal:
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* DB_LOCK_DOALL: Unlock all references in this lock (instead of only 1).
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* DB_LOCK_FREE: Free the lock (used in checklocker).
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* DB_LOCK_IGNOREDEL: Remove from the locker hash table even if already
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deleted (used in checklocker).
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* DB_LOCK_NOPROMOTE: Don't bother running promotion when releasing locks
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* (used by CDB___lock_put_internal).
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* DB_LOCK_UNLINK: Remove from the locker links (used in checklocker).
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*/
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#define DB_LOCK_DOALL 0x001
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#define DB_LOCK_FREE 0x002
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#define DB_LOCK_IGNOREDEL 0x004
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#define DB_LOCK_NOPROMOTE 0x008
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#define DB_LOCK_UNLINK 0x010
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/*
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* Macros to get/release different types of mutexes.
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*/
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#define OBJECT_LOOKUP(lt, ndx, dbt, sh_obj) \
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HASHLOOKUP((lt)->objtab, \
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ndx, __db_lockobj, links, dbt, sh_obj, CDB___lock_cmp);
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#ifdef FINE_GRAIN
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#define OBJECT_LOCK_NDX(lt, ndx) \
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MUTEX_LOCK(&(lt)->osynch_tab[ndx], (lt)->dbenv->lockfhp)
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#define OBJECT_LOCK(lt, reg, obj, ndx) \
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HASHACCESS((lt)->osynch_tab, obj, \
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(reg)->table_size, CDB___lock_ohash, ndx, (lt)->dbenv->lockfhp)
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#define SHOBJECT_LOCK(lt, reg, shobj, ndx) \
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HASHACCESS((lt)->osynch_tab, shobj, \
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(reg)->table_size, CDB___lock_lhash, ndx, (lt)->dbenv->lockfhp)
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#define OBJECT_UNLOCK(lt, ndx) \
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MUTEX_UNLOCK(&(lt)->osynch_tab[ndx])
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#else
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#define OBJECT_LOCK_NDX(lt, ndx)
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#define OBJECT_LOCK(lt, reg, obj, ndx) \
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ndx = CDB___lock_ohash(obj) % (reg)->table_size
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#define SHOBJECT_LOCK(lt, reg, shobj, ndx) \
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ndx = CDB___lock_lhash(shobj) % (reg)->table_size
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#define OBJECT_UNLOCK(lt, ndx)
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#endif
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#define LOCKER_LOOKUP(lt, ndx, locker, sh_locker) \
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HASHLOOKUP((lt)->lockertab, \
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ndx, __db_locker, links, locker, sh_locker, CDB___lock_locker_cmp);
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#ifdef FINE_GRAIN
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#define LOCKER_LOCK_NDX(lt, ndx) \
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MUTEX_LOCK(&(lt)->lsynch_tab[ndx], (lt)->dbenv->lockfhp)
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#define LOCKER_LOCK(lt, reg, locker, ndx) \
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HASHACCESS((lt)->lsynch_tab, locker, \
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reg->table_size, CDB___lock_locker_hash, ndx, (lt)->dbenv->lockfhp)
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#define LOCKER_UNLOCK(lt, ndx) \
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MUTEX_UNLOCK(&(lt)->lsynch_tab[ndx])
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#define MEMORY_LOCK(lt) \
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MUTEX_LOCK((lt)->memlock, (lt)->dbenv->lockfhp)
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#define MEMORY_UNLOCK(lt) \
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MUTEX_UNLOCK((lt)->memlock)
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#else
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#define LOCKER_LOCK_NDX(lt, ndx)
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#define LOCKER_LOCK(lt, reg, locker, ndx) \
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ndx = CDB___lock_locker_hash(locker) % (reg)->table_size
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#define LOCKER_UNLOCK(lt, ndx)
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#define MEMORY_LOCK(lt)
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#define MEMORY_UNLOCK(lt)
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#endif
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#ifdef FINE_GRAIN
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#define LOCKREGION(dbenv, lt)
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#define UNLOCKREGION(dbenv, lt)
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#else
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#define LOCKREGION(dbenv, lt) R_LOCK((dbenv), &(lt)->reginfo)
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#define UNLOCKREGION(dbenv, lt) R_UNLOCK((dbenv), &(lt)->reginfo)
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#endif
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#include "lock_ext.h"
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