DB_ENV->lock_stat(DB_ENV *env, DB_LOCK_STAT **statp, u_int32_t flags);
The DB_ENV->lock_stat method returns the locking subsystem statistics.
The flags value must be set to 0 or
the following value:
- Reset statistics after returning their values.
The DB_ENV->lock_stat method creates a statistical structure of type
DB_LOCK_STAT and copies a pointer to it into a user-specified memory
Statistical structures are created in allocated memory. If application-specific allocation
routines have been declared (see DB_ENV->set_alloc for more
information), they are used to allocate the memory; otherwise, the
library malloc(3) interface is used. The caller is
responsible for deallocating the memory. To deallocate the memory, free
the memory reference; references inside the returned memory need not be
The following DB_LOCK_STAT fields will be filled in:
- u_int32_t st_id;
- The last allocated locker ID.
- u_int32_t st_cur_maxid;
- The current maximum unused locker ID.
- u_int32_t st_nmodes;
- The number of lock modes.
- u_int32_t st_maxlocks;
- The maximum number of locks possible.
- u_int32_t st_maxlockers;
- The maximum number of lockers possible.
- u_int32_t st_maxobjects;
- The maximum number of lock objects possible.
- u_int32_t st_nlocks;
- The number of current locks.
- u_int32_t st_maxnlocks;
- The maximum number of locks at any one time.
- u_int32_t st_nlockers;
- The number of current lockers.
- u_int32_t st_maxnlockers;
- The maximum number of lockers at any one time.
- u_int32_t st_nobjects;
- The number of current lock objects.
- u_int32_t st_maxnobjects;
- The maximum number of lock objects at any one time.
- u_int32_t st_nrequests;
- The total number of locks requested.
- u_int32_t st_nreleases;
- The total number of locks released.
- u_int32_t st_nnowaits;
- The total number of lock requests failing because
DB_LOCK_NOWAIT was set.
- u_int32_t st_nconflicts;
- The total number of locks not immediately available due to conflicts.
- u_int32_t st_ndeadlocks;
- The number of deadlocks.
- u_int32_t st_locktimeout;
- Lock timeout value.
- u_int32_t st_nlocktimeouts;
- The number of locks that have timed out.
- u_int32_t st_txntimeout;
- Transaction timeout value.
- u_int32_t st_ntxntimeouts;
- The number of transactions that have timed out. This value is also a
component of st_ndeadlocks, the total number of deadlocks
- u_int32_t st_regsize;
- The size of the lock region.
- u_int32_t st_region_wait;
- The number of times that a thread of control was forced to wait before
obtaining the region lock.
- u_int32_t st_region_nowait;
- The number of times that a thread of control was able to obtain
the region lock without waiting.
The DB_ENV->lock_stat method returns a non-zero error value on failure and 0 on success.
The DB_ENV->lock_stat method may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
If a catastrophic error has occurred, the DB_ENV->lock_stat method may fail and
in which case all subsequent Berkeley DB calls will fail in the same way.
Locking Subsystem and Related Methods
Copyright Sleepycat Software