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<p>Library Version 11.2.5.3</p>
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<th colspan="3" align="center">DbEnv::lock_detect()</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="envset_lk_tablesize.html">Prev</a> </td>
<th width="60%" align="center">Chapter 7.
The DbLock Handle
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<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="lockdetect"></a>DbEnv::lock_detect()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::lock_detect(u_int32_t flags, u_int32_t atype, int *rejected);</pre>
<p>
The <code class="methodname">DbEnv::lock_detect()</code> 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>
<p>
The <code class="methodname">DbEnv::lock_detect()</code> <span>
<span>
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.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp8032192"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp8032040"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter is currently
unused, and must be set to 0.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp8024496"></a>atype</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>atype</strong></span> parameter specifies which
lock request(s) to reject. The deadlock detector will reject the lock
request with the lowest priority. If multiple lock requests have the
lowest priority, then the <span class="bold"><strong>atype</strong></span>
parameter is used to select which of those lock requests to reject.
It must be set to one of the following list:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p><a id="detect_DB_LOCK_DEFAULT"></a>
<code class="literal">DB_LOCK_DEFAULT</code>
</p>
<p>
Use the default lock policy, which is DB_LOCK_RANDOM.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_EXPIRE"></a>
<code class="literal">DB_LOCK_EXPIRE</code>
</p>
<p>
Reject lock requests which have timed out. No other deadlock
detection is performed.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_MAXLOCKS"></a>
<code class="literal">DB_LOCK_MAXLOCKS</code>
</p>
<p>
Reject the lock request for the locker ID with the most locks.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_MAXWRITE"></a>
<code class="literal">DB_LOCK_MAXWRITE</code>
</p>
<p>
Reject the lock request for the locker ID with the most write locks.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_MINLOCKS"></a>
<code class="literal">DB_LOCK_MINLOCKS</code>
</p>
<p>
Reject the lock request for the locker ID with the fewest locks.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_MINWRITE"></a>
<code class="literal">DB_LOCK_MINWRITE</code>
</p>
<p>
Reject the lock request for the locker ID with the fewest write locks.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_OLDEST"></a>
<code class="literal">DB_LOCK_OLDEST</code>
</p>
<p>
Reject the lock request for the locker ID with the oldest lock.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_RANDOM"></a>
<code class="literal">DB_LOCK_RANDOM</code>
</p>
<p>
Reject the lock request for a random locker ID.
</p>
</li>
<li>
<p><a id="detect_DB_LOCK_YOUNGEST"></a>
<code class="literal">DB_LOCK_YOUNGEST</code>
</p>
<p>
Reject the lock request for the locker ID with the youngest lock.
</p>
</li>
</ul>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp8047296"></a>rejected</h4>
</div>
</div>
</div>
<p>
If the <span class="bold"><strong>rejected</strong></span> parameter is
non-NULL, the memory location to which it refers will be set to the
number of lock requests that were rejected.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp8012488"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::lock_detect()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp8025848"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
An invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp8040784"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>, <a class="link" href="lock.html" title="Chapter 7. The DbLock Handle">DbLock</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp8035464"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="lock.html#locklist" title="Locking Subsystem and Related Methods">Locking Subsystem and Related Methods</a>
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