Berkeley DB: DbEnv::lock

DbEnv::lock_stat

#include <db_cxx.h> int DbEnv::lock_stat(DB_LOCK_STAT **statp, u_int32_t flags); int DbEnv::lock_stat_print(u_int32_t flags); Description: DbEnv::lock_stat The DbEnv::lock_stat method returns the locking subsystem statistics. The DbEnv::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 DbEnv::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_nupgrade; The total number of locks upgraded. u_int32_t st_ndowngrade; The total number of locks downgraded. u_int32_t st_lock_wait; The number of lock requests not immediately available due to conflicts, for which the thread of control waited. u_int32_t st_lock_nowait; The number of lock requests not immediately available due to conflicts, for which the thread of control did not wait. 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. roff_t st_regsize; The size of the lock region, in bytes. u_int32_t st_region_wait; The number of times that a thread of control was forced to wait before obtaining the lock region mutex. u_int32_t st_region_nowait; The number of times that a thread of control was able to obtain the lock region mutex without waiting. The DbEnv::lock_stat method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 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 DbEnv::lock_stat method may fail and throw DbException, encapsulating one of the following non-zero errors, or return one of the following non-zero errors: EINVAL An invalid flag value or parameter was specified. Description: DbEnv::lock_stat_print The DbEnv::lock_stat_print method prints diagnostic information to the output channel described by the DbEnv::set_msgfile method. The DbEnv::lock_stat_print method may not be called before the DbEnv::open method has been called. The DbEnv::lock_stat_print method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. Parameters flags The flags parameter must be set by bitwise inclusively OR'ing together one or more of the following values: DB_STAT_ALL Display all available information. DB_STAT_LOCK_CONF Display the lock conflict matrix. DB_STAT_LOCK_LOCKERS Display the lockers within hash chains. DB_STAT_LOCK_OBJECTS Display the lock objects within hash chains. DB_STAT_LOCK_PARAMS Display the locking subsystem parameters. Class DbEnv, DbLock See Also Locking Subsystem and Related Methods