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_partitions;The number of lock table partitions. u_int32_t st_nlocks;The number of current locks. u_int32_t st_maxnlocks;The maximum number of locks at any one time. Note that if there is more than one partition, this is the sum of the maximum across all partitions. u_int32_t st_maxhlocks;The maximum number of locks in any hash bucket at any one time. u_int32_t st_locksteals;The maximum number of locks stolen by for an empty partition. u_int32_t st_maxlsteals;The maximum number of lock steals for any one partition. 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. Note that if there is more than one partition this is the sum of the maximum across all partitions. u_int32_t st_maxhobjects;The maximum number of objects in any hash bucket at any one time. u_int32_t st_objectsteals;The maximum number of objects stolen by for an empty partition. u_int32_t st_maxosteals;The maximum number of object steals for any one partition. 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. u_int32_t st_objs_wait;The number of requests to allocate or deallocate an object for which the thread of control waited. u_int32_t st_objs_nowait;The number of requests to allocate or deallocate an object for which the thread of control did not wait. u_int32_t st_lockers_wait;The number of requests to allocate or deallocate a locker for which the thread of control waited. u_int32_t st_lockers_nowait;The number of requests to allocate or deallocate a locker for which the thread of control did not wait. u_int32_t st_hash_len;Maximum length of a lock hash bucket. roff_t st_regsize;The size of the lock region, in bytes. u_int32_t st_part_wait;The number of times that a thread of control was forced to wait before obtaining the lock partition mutex. u_int32_t st_part_nowait;The number of times that a thread of control was able to obtain the lock partition mutex without waiting. u_int32_t st_part_max_wait;The maximum number of times that a thread of control was forced to wait before obtaining any one lock partition mutex. u_int32_t st_part_max_nowait;The number of times that a thread of control was able to obtain any one lock partition mutex without waiting. 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 may not be called before the DbEnv::open method is called. 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 flagsThe flags parameter must be set to 0 or the following value: DB_STAT_CLEARReset statistics after returning their values. statpThe 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: EINVALAn invalid flag value or parameter was specified. Description: DbEnv::lock_stat_print The DbEnv::lock_stat_print method displays the locking subsystem statistical information, as described for the DbEnv::lock_stat method. The information is printed to a specified output channel (see the DbEnv::set_msgfile method for more information), or passed to an application callback function (see the DbEnv::set_msgcall method for more information). The DbEnv::lock_stat_print method may not be called before the DbEnv::open method is 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 flagsThe flags parameter must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values: DB_STAT_ALLDisplay all available information. DB_STAT_CLEARReset statistics after displaying their values. DB_STAT_LOCK_CONFDisplay the lock conflict matrix. DB_STAT_LOCK_LOCKERSDisplay the lockers within hash chains. DB_STAT_LOCK_OBJECTSDisplay the lock objects within hash chains. DB_STAT_LOCK_PARAMSDisplay the locking subsystem parameters. Class DbEnv, DbLock See Also Locking Subsystem and Related Methods