Berkeley DB: DB_ENV->mutex

DB_ENV->mutex_stat

#include <db.h> int DB_ENV->mutex_stat(DB_ENV *env, DB_MUTEX_STAT **statp, u_int32_t flags); int DB_ENV->mutex_stat_print(DB_ENV *env, u_int32_t flags); Description: DB_ENV->mutex_stat The DB_ENV->mutex_stat method returns the mutex subsystem statistics. The DB_ENV->mutex_stat method creates a statistical structure of type DB_MUTEX_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_MUTEX_STAT fields will be filled in: u_int32_t st_mutex_align;The mutex alignment, in bytes. u_int32_t st_mutex_tas_spins;The number of times test-and-set mutexes will spin without blocking. int st_mutex_cnt;The total number of mutexes configured. u_int32_t st_mutex_free;The number of mutexes currently available. u_int32_t st_mutex_inuse;The number of mutexes currently in use. u_int32_t st_mutex_inuse_max;The maximum number of mutexes ever in use. roff_t st_regsize;The size of the mutex 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 mutex region mutex. u_int32_t st_region_nowait;The number of times that a thread of control was able to obtain the mutex region mutex without waiting. The DB_ENV->mutex_stat method may not be called before the DB_ENV->open method is called. The DB_ENV->mutex_stat method returns a non-zero error value on failure and 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 DB_ENV->mutex_stat method may fail and return one of the following non-zero errors: EINVALAn invalid flag value or parameter was specified. Description: DB_ENV->mutex_stat_print The DB_ENV->mutex_stat_print method displays the mutex subsystem statistical information, as described for the DB_ENV->mutex_stat method. The information is printed to a specified output channel (see the DB_ENV->set_msgfile method for more information), or passed to an application callback function (see the DB_ENV->set_msgcall method for more information). The DB_ENV->mutex_stat_print method may not be called before the DB_ENV->open method is called. The DB_ENV->mutex_stat_print method returns a non-zero error value on failure and 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. Class DB_ENV See Also Database Environments and Related Methods