DbEnv::lock_stat
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#include <db_cxx.h>
int
DbEnv::lock_stat(DB_LOCK_STAT **statp, void *(*db_malloc)(size_t));
Description
The DbEnv::lock_stat method
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 the returned memory, free each returned memory pointer;
pointers inside the 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_lockid;
- 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 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.
Errors
If a fatal error occurs in Berkeley DB, the DbEnv::lock_stat method will fail and either
return DB_RUNRECOVERY or throw an exception encapsulating
DB_RUNRECOVERY, at which point all subsequent database calls will
fail in the same way.
In addition, the DbEnv::lock_stat method may fail and
throw an exception or return a non-zero error
for errors specified for other Berkeley DB and C library or system methods.
Classes
DbEnv, DbLock
See Also
DbEnv::set_lk_conflicts,
DbEnv::set_lk_detect,
DbEnv::set_lk_max,
DbEnv::lock_detect,
DbEnv::lock_get,
DbEnv::lock_id,
DbLock::put,
DbEnv::lock_stat
and
DbEnv::lock_vec.
Copyright Sleepycat Software