<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>DbEnv::mutex_set_tas_spins()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="mutex.html" title="Chapter 10. Mutex Methods" /> <link rel="prev" href="mutexset_max.html" title="DbEnv::mutex_set_max()" /> <link rel="next" href="mutexstat.html" title="DbEnv::mutex_stat()" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DbEnv::mutex_set_tas_spins()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="mutexset_max.html">Prev</a> </td> <th width="60%" align="center">Chapter 10. Mutex Methods </th> <td width="20%" align="right"> <a accesskey="n" href="mutexstat.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="mutexset_tas_spins"></a>DbEnv::mutex_set_tas_spins()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> int DbEnv::mutex_set_tas_spins(u_int32_t tas_spins); </pre> <p> Specify that test-and-set mutexes should spin <span class="bold"><strong>tas_spins</strong></span> times without blocking. The value defaults to 1 on uniprocessor systems and to 50 times the number of processors on multiprocessor systems. </p> <p> The database environment's test-and-set spin count 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 "set_tas_spins", one or more whitespace characters, and the number of spins. 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_tas_spins()</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::mutex_set_tas_spins()</code> method may be called at any time during the life of the application. </p> <p> The <code class="methodname">DbEnv::mutex_set_tas_spins()</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="id1699587"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1699519"></a>tas_spins</h4> </div> </div> </div> <p> The <span class="bold"><strong>tas_spins</strong></span> parameter is the number of spins test-and-set mutexes should execute before blocking. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1699845"></a>Errors</h3> </div> </div> </div> <p> The <code class="methodname">DbEnv::mutex_set_tas_spins()</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="id1699620"></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="id1699560"></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="id1699777"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="mutex.html#mutexlist" title="Mutex Methods">Mutex Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="mutexset_max.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="mutex.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="mutexstat.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DbEnv::mutex_set_max() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DbEnv::mutex_stat()</td> </tr> </table> </div> </body> </html>