Berkeley DB: DB_ENV->lock_detect
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++

### DB_ENV->lock_detect |

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###

    #include <db.h>

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

### Description: DB_ENV->lock_detect

The DB_ENV->lock_detect method 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 DB_ENV->lock_detect method is the underlying method 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 method returns a non-zero error value on failure and 0 on success.

### Parameters

aborted

atype
  The atype parameter specifies which lock request(s) to reject. It must be set to one of the 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.

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

### Errors

The DB_ENV->lock_detect method may fail and return one of the following non-zero errors:

EINVAL
  An invalid flag value or parameter was specified.

### Class

DB_ENV, DB_LOCK

### See Also

Locking Subsystem and Related Methods`

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