lock_stat
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#include <db.h>
int
lock_stat(DB_ENV *env,
DB_LOCK_STAT **statp, void *(*db_malloc)(size_t));
Description
The lock_stat function
creates a statistical structure and copies a pointer to it into a
user-specified memory location.
Statistical structures are created in allocated memory. If db_malloc is non-NULL, it
is called to allocate the memory, otherwise, the library function
malloc(3) is used. The function db_malloc must match
the calling conventions of the malloc(3) library routine.
Regardless, the caller is responsible for deallocating the returned
memory. To deallocate returned memory, free the returned memory
reference, references inside the returned memory do not need to be
individually freed.
The lock region statistics are stored in a structure of type
DB_LOCK_STAT. The following DB_LOCK_STAT fields will be filled in:
- u_int32_t st_lastid;
- The last allocated lock 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_nlockers;
- The number of current lockers.
- u_int32_t st_maxnlockers;
- The maximum number of lockers 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_nconflicts;
- The total number of locks not immediately available due to conflicts.
- u_int32_t st_ndeadlocks;
- The number of deadlocks detected.
- u_int32_t st_regsize;
- The size of the 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 lock_stat
function returns a non-zero error value on failure and 0 on success.
Errors
If a fatal error occurs in Berkeley DB, the lock_stat function will fail and return
DB_RUNRECOVERY, at which point all subsequent database calls will
fail in the same way.
In addition, the lock_stat function may fail and
return a non-zero error
for errors specified for other Berkeley DB and C library or system functions.
See Also
DBENV->set_lk_conflicts,
DBENV->set_lk_detect,
DBENV->set_lk_max,
lock_detect,
lock_get,
lock_id,
lock_put,
lock_stat
and
lock_vec.
Copyright Sleepycat Software