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<div class="sect1" lang="en" xml:lang="en">
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<h2 class="title" style="clear: both"><a id="envset_isalive"></a>DbEnv::set_isalive()</h2>
</div>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::set_isalive(int (*is_alive)(DbEnv *dbenv, pid_t pid,
db_threadid_t tid, u_int32_t flags));</pre>
<p>
Declare a function that returns if a thread of control (either a true
thread or a process) is still running. The <code class="methodname">DbEnv::set_isalive()</code>
method supports the <a class="xref" href="envfailchk.html" title="DbEnv::failchk()">DbEnv::failchk()</a> method.
For more information, see
<a href="../../programmer_reference/cam_app.html" class="olink">Architecting Data Store and Concurrent
Data Store applications</a>, and
<a href="../../programmer_reference/transapp_app.html" class="olink">Architecting Transactional Data Store
applications</a>, both in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
</p>
<p>
The <code class="methodname">DbEnv::set_isalive()</code> method configures operations performed
using the specified <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle, not all
operations performed on the underlying database environment.
</p>
<p>
The <code class="methodname">DbEnv::set_isalive()</code> method may be called at any time during the
life of the application.
</p>
<p>
The <code class="methodname">DbEnv::set_isalive()</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="idp7484736"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp7484472"></a>is_alive</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>is_alive</strong></span> parameter is a function
which returns non-zero if the thread of control, identified by the
<span class="bold"><strong>pid</strong></span> and <span class="bold"><strong>tid</strong></span> arguments, is still running. The function
takes four arguments:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span class="bold"><strong>dbenv</strong></span>
</p>
<p>
The <span class="bold"><strong>dbenv</strong></span> parameter is the enclosing
database environment handle, allowing application access to the
application-private fields of that object.
</p>
</li>
<li>
<p>
<span class="bold"><strong>pid</strong></span>
</p>
<p>
The <span class="bold"><strong>pid</strong></span> parameter is a process ID
returned by the function specified to the
<a class="xref" href="envset_thread_id.html" title="DbEnv::set_thread_id()">DbEnv::set_thread_id()</a>
method.
</p>
</li>
<li>
<p>
<span class="bold"><strong>tid</strong></span>
</p>
<p>
The <span class="bold"><strong>tid</strong></span> parameter is a thread ID
returned by the function specified to the
<a class="xref" href="envset_thread_id.html" title="DbEnv::set_thread_id()">DbEnv::set_thread_id()</a>
method.
</p>
</li>
<li>
<p>
<span class="bold"><strong>flags</strong></span>
</p>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
or the following value:
</p>
<div class="itemizedlist">
<ul type="circle">
<li>
<p><a id="isalive_DB_MUTEX_PROCESS_ONLY"></a>
<code class="literal">DB_MUTEX_PROCESS_ONLY</code>
</p>
<p>
Return only if the process is alive, the thread ID
should be ignored.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp7503912"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::set_isalive()</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="idp7517976"></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="idp7519816"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp7515280"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a>
</p>
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