<?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>DB_ENV->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 9. Mutex Methods" />
<link rel="prev" href="mutexset_max.html" title="DB_ENV->mutex_set_max()" />
<link rel="next" href="mutexstat.html" title="DB_ENV->mutex_stat()" />
</head>
<body>
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DB_ENV->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 9.
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>DB_ENV->mutex_set_tas_spins()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db.h>
int
DB_ENV->mutex_set_tas_spins(DB_ENV *dbenv, 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">DB_ENV->mutex_set_tas_spins()</code> method configures operations
performed using the specified
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle, not all
operations performed on the underlying database environment.
</p>
<p>
The <code class="methodname">DB_ENV->mutex_set_tas_spins()</code> method may be called at any time
during the life of the application.
</p>
<p>
The <code class="methodname">DB_ENV->mutex_set_tas_spins()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1695310"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1695244"></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="id1694816"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DB_ENV->mutex_set_tas_spins()</code> <span>
<span>
method may fail and 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="id1695335"></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="id1695341"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1695299"></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">DB_ENV->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"> DB_ENV->mutex_stat()</td>
</tr>
</table>
</div>
</body>
</html>
