1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>DB_ENV->mutex_set_tas_spins()</title> 7 <link rel="stylesheet" href="apiReference.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> 10 <link rel="up" href="mutex.html" title="Chapter 9. Mutex Methods" /> 11 <link rel="prev" href="mutexset_max.html" title="DB_ENV->mutex_set_max()" /> 12 <link rel="next" href="mutexstat.html" title="DB_ENV->mutex_stat()" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DB_ENV->mutex_set_tas_spins()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="mutexset_max.html">Prev</a> </td> 22 <th width="60%" align="center">Chapter 9. 23 Mutex Methods 24 </th> 25 <td width="20%" align="right"> <a accesskey="n" href="mutexstat.html">Next</a></td> 26 </tr> 27 </table> 28 <hr /> 29 </div> 30 <div class="sect1" lang="en" xml:lang="en"> 31 <div class="titlepage"> 32 <div> 33 <div> 34 <h2 class="title" style="clear: both"><a id="mutexset_tas_spins"></a>DB_ENV->mutex_set_tas_spins()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db.h> 39 40int 41DB_ENV->mutex_set_tas_spins(DB_ENV *dbenv, u_int32_t tas_spins); </pre> 42 <p> 43 Specify that test-and-set mutexes should spin <span class="bold"><strong>tas_spins</strong></span> times without blocking. The value 44 defaults to 1 on uniprocessor systems and to 50 times the number of 45 processors on multiprocessor systems. 46 </p> 47 <p> 48 The database environment's test-and-set spin count may also be 49 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 50 syntax of the entry in that file is a single line with the string 51 "set_tas_spins", one or more whitespace characters, and the number of 52 spins. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is 53 read when the database environment is opened, it will silently 54 overrule configuration done before that time. 55 </p> 56 <p> 57 The <code class="methodname">DB_ENV->mutex_set_tas_spins()</code> method configures operations 58 performed using the specified 59 <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle, not all 60 operations performed on the underlying database environment. 61 </p> 62 <p> 63 The <code class="methodname">DB_ENV->mutex_set_tas_spins()</code> method may be called at any time 64 during the life of the application. 65 </p> 66 <p> 67 The <code class="methodname">DB_ENV->mutex_set_tas_spins()</code> <span> 68 <span> 69 method returns a non-zero error value on failure and 0 on success. 70 </span> 71 72 </span> 73 </p> 74 <div class="sect2" lang="en" xml:lang="en"> 75 <div class="titlepage"> 76 <div> 77 <div> 78 <h3 class="title"><a id="id1695310"></a>Parameters</h3> 79 </div> 80 </div> 81 </div> 82 <div class="sect3" lang="en" xml:lang="en"> 83 <div class="titlepage"> 84 <div> 85 <div> 86 <h4 class="title"><a id="id1695244"></a>tas_spins</h4> 87 </div> 88 </div> 89 </div> 90 <p> 91 The <span class="bold"><strong>tas_spins</strong></span> parameter is the number 92 of spins test-and-set mutexes should execute before blocking. 93 </p> 94 </div> 95 </div> 96 <div class="sect2" lang="en" xml:lang="en"> 97 <div class="titlepage"> 98 <div> 99 <div> 100 <h3 class="title"><a id="id1694816"></a>Errors</h3> 101 </div> 102 </div> 103 </div> 104 <p> 105 The <code class="methodname">DB_ENV->mutex_set_tas_spins()</code> <span> 106 <span> 107 method may fail and return one of the following non-zero errors: 108 </span> 109 110 </span> 111 </p> 112 <div class="sect3" lang="en" xml:lang="en"> 113 <div class="titlepage"> 114 <div> 115 <div> 116 <h4 class="title"><a id="id1695335"></a>EINVAL</h4> 117 </div> 118 </div> 119 </div> 120 <p> 121 An invalid flag value or parameter was specified. 122 </p> 123 </div> 124 </div> 125 <div class="sect2" lang="en" xml:lang="en"> 126 <div class="titlepage"> 127 <div> 128 <div> 129 <h3 class="title"><a id="id1695341"></a>Class</h3> 130 </div> 131 </div> 132 </div> 133 <p> 134 <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> 135 </p> 136 </div> 137 <div class="sect2" lang="en" xml:lang="en"> 138 <div class="titlepage"> 139 <div> 140 <div> 141 <h3 class="title"><a id="id1695299"></a>See Also</h3> 142 </div> 143 </div> 144 </div> 145 <p> 146 <a class="xref" href="mutex.html#mutexlist" title="Mutex Methods">Mutex Methods</a> 147 </p> 148 </div> 149 </div> 150 <div class="navfooter"> 151 <hr /> 152 <table width="100%" summary="Navigation footer"> 153 <tr> 154 <td width="40%" align="left"><a accesskey="p" href="mutexset_max.html">Prev</a> </td> 155 <td width="20%" align="center"> 156 <a accesskey="u" href="mutex.html">Up</a> 157 </td> 158 <td width="40%" align="right"> <a accesskey="n" href="mutexstat.html">Next</a></td> 159 </tr> 160 <tr> 161 <td width="40%" align="left" valign="top">DB_ENV->mutex_set_max() </td> 162 <td width="20%" align="center"> 163 <a accesskey="h" href="index.html">Home</a> 164 </td> 165 <td width="40%" align="right" valign="top"> DB_ENV->mutex_stat()</td> 166 </tr> 167 </table> 168 </div> 169 </body> 170</html> 171