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<h2 class="title" style="clear: both"><a id="mutexset_init"></a>DbEnv::mutex_set_init()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::mutex_set_init(u_int32_t init); </pre>
<p>
Configure the inital number of mutexes to allocate.
</p>
<p>
Berkeley DB allocates a default number of mutexes based on the
initial configuration of the database environment. The
<code class="methodname">DbEnv::mutex_set_init()</code> method is used to
override this default number of mutexes to allocate. This may be done
to either speed up startup, or to force more work to be done at
startup to avoid later contention due to allocation.
</p>
<p>
The database environment's inital number of mutexes may also be
configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The syntax
of the entry in that file is a single line with the string
"mutex_set_init", one or more whitespace characters, and the
initial number of mutexes. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is read
when the database environment is opened, it will silently overrule
configuration done before that time.
</p>
<p>
The <code class="methodname">DbEnv::mutex_set_init()</code> method
configures a database environment, not only operations performed
using the specified <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
handle.
</p>
<p>
The <code class="methodname">DbEnv::mutex_set_init()</code> method may not
be called after the
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method is
called. If the database environment already exists when
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> is called, the
information specified to
<code class="methodname">DbEnv::mutex_set_init()</code> will be ignored.
</p>
<p>
The <code class="methodname">DbEnv::mutex_set_init()</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>
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<h3 class="title"><a id="idp3867008"></a>Parameters</h3>
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<h4 class="title"><a id="idp3866856"></a>init</h4>
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<p>
The <span class="bold"><strong>init</strong></span> parameter is the absolute
number of mutexes to allocate.
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<h3 class="title"><a id="idp3855672"></a>Errors</h3>
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<p>
The <code class="methodname">DbEnv::mutex_set_init()</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>
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<div class="sect3" lang="en" xml:lang="en">
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<h4 class="title"><a id="idp3875760"></a>EINVAL</h4>
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<p>
An invalid flag value or parameter was specified.
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<h3 class="title"><a id="idp3874464"></a>Class</h3>
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<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
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<h3 class="title"><a id="idp3869704"></a>See Also</h3>
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<p>
<a class="xref" href="mutex.html#mutexlist" title="Mutex Methods">Mutex Methods</a>
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