#include <db.h>

int
DB_ENV->lock_detect(DB_ENV *env,
    u_int32_t flags, u_int32_t atype, int *aborted);

Description

The DB_ENV->lock_detect function runs one iteration of the deadlock detector. The deadlock detector traverses the lock table and marks one of the participating lock requesters for rejection in each deadlock it finds.

The flags parameter is currently unused, and must be set to 0.

The atype parameter specifies which lock request(s) to reject. It must be set to one following list:

DB_LOCK_DEFAULT

Use whatever lock policy was specified when the database environment was created. If no lock policy has yet been specified, set the lock policy to DB_LOCK_RANDOM.

DB_LOCK_EXPIRE

Reject lock requests which have timed out. No other deadlock detection is performed.

DB_LOCK_MAXLOCKS

Reject the lock request for the locker ID with the greatest number of locks.

DB_LOCK_MINLOCKS

Reject the lock request for the locker ID with the fewest number of locks.

DB_LOCK_MINWRITE

Reject the lock request for the locker ID with the fewest number of write locks.

DB_LOCK_OLDEST

Reject the lock request for the oldest locker ID.

DB_LOCK_RANDOM

Reject the lock request for a random locker ID.

DB_LOCK_YOUNGEST

Reject the lock request for the youngest locker ID.

If the aborted parameter is non-NULL, the memory location to which it refers will be set to the number of lock requests that were rejected.

The DB_ENV->lock_detect function is the underlying function used by the db_deadlock utility. See the db_deadlock utility source code for an example of using DB_ENV->lock_detect in a IEEE/ANSI Std 1003.1 (POSIX) environment.

The DB_ENV->lock_detect function returns a non-zero error value on failure and 0 on success.

Errors

The DB_ENV->lock_detect function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB_ENV->lock_detect function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

See Also