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<h1>DB_ENV->lock_detect</h1>
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<h3><pre>
#include <db.h>
<p>
int
DB_ENV->lock_detect(DB_ENV *env,
u_int32_t flags, u_int32_t atype, int *aborted);
</pre></h3>
<h1>Description</h1>
<p>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.
<p>The <b>flags</b> parameter is currently unused, and must be set to 0.
<p>The <b>atype</b> parameter specifies which lock request(s) to reject.
It must be set to one following list:
<p><dl compact>
<p><dt><a name="DB_LOCK_DEFAULT">DB_LOCK_DEFAULT</a><dd>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.
<dt><a name="DB_LOCK_EXPIRE">DB_LOCK_EXPIRE</a><dd>Reject lock requests which have timed out. No other deadlock detection
is performed.
<dt><a name="DB_LOCK_MAXLOCKS">DB_LOCK_MAXLOCKS</a><dd>Reject the lock request for the locker ID with the greatest number of
locks.
<dt><a name="DB_LOCK_MINLOCKS">DB_LOCK_MINLOCKS</a><dd>Reject the lock request for the locker ID with the fewest number of
locks.
<dt><a name="DB_LOCK_MINWRITE">DB_LOCK_MINWRITE</a><dd>Reject the lock request for the locker ID with the fewest number of
write locks.
<dt><a name="DB_LOCK_OLDEST">DB_LOCK_OLDEST</a><dd>Reject the lock request for the oldest locker ID.
<dt><a name="DB_LOCK_RANDOM">DB_LOCK_RANDOM</a><dd>Reject the lock request for a random locker ID.
<dt><a name="DB_LOCK_YOUNGEST">DB_LOCK_YOUNGEST</a><dd>Reject the lock request for the youngest locker ID.
</dl>
<p>If the <b>aborted</b> parameter is non-NULL, the memory location to
which it refers will be set to the number of lock requests that were
rejected.
<p>The DB_ENV->lock_detect method is the underlying interface used by the <a href="../../db4-4.1.25/utility/db_deadlock.html">db_deadlock</a> utility.
See the <a href="../../db4-4.1.25/utility/db_deadlock.html">db_deadlock</a> utility source code for an example of using DB_ENV->lock_detect
in a IEEE/ANSI Std 1003.1 (POSIX) environment.
<p>The DB_ENV->lock_detect method returns a non-zero error value on failure and 0 on success.
<h1>Errors</h1>
<p>The DB_ENV->lock_detect method 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 method may fail and
return <a href="../../db4-devel-4.1.25/ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>,
in which case all subsequent Berkeley DB calls will fail in the same way.
<h1>Class</h1>
<a href="../../db4-devel-4.1.25/api_c/env_class.html">DB_ENV</a>, <a href="../../db4-devel-4.1.25/api_c/lock_class.html">DB_LOCK</a>
<h1>See Also</h1>
<a href="../../db4-devel-4.1.25/api_c/lock_list.html">Locking Subsystem and Related Methods</a>
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