Berkeley DB: DB_ENV->lock

DB_ENV->lock_stat

#include <db.h> int DB_ENV->lock_stat(DB_ENV *env, DB_LOCK_STAT **statp, u_int32_t flags); Description: DB_ENV->lock_stat The DB_ENV->lock_stat method returns the locking subsystem statistics. 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 location. Statistical structures are stored 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 standard C library malloc(3) 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 individually freed. 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 lock requests 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 detected. 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. Parameters flags The flags parameter must be set to 0 or the following value: DB_STAT_CLEAR Reset statistics after returning their values. statp The statp parameter references memory into which a pointer to the allocated statistics structure is copied. Errors The DB_ENV->lock_stat method may fail and return one of the following non-zero errors: EINVAL An invalid flag value or parameter was specified. Class DB_ENV, DB_LOCK See Also Locking Subsystem and Related Methods