1<!--$Id: mutex_set_tas_spins.so,v 10.30 2005/07/20 16:34:01 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: DB_ENV->mutex_set_tas_spins</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>DB_ENV->mutex_set_tas_spins</b> 14</td> 15<td align=right> 16<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a> 17<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db.h> 23<p> 24int 25DB_ENV->mutex_set_tas_spins(DB_ENV *dbenv, u_int32_t tas_spins); 26<p> 27int 28DB_ENV->mutex_get_tas_spins(DB_ENV *dbenv, u_int32_t *tas_spinsp); 29</pre></b> 30<hr size=1 noshade> 31<b>Description: DB_ENV->mutex_set_tas_spins</b> 32<p>Specify that test-and-set mutexes should spin <b>tas_spins</b> times 33without blocking. The value defaults to 1 on uniprocessor systems and 34to 50 times the number of processors on multiprocessor systems.</p> 35<p>The database environment's test-and-set spin count may also be configured using the 36environment's <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file. The syntax of the entry in that 37file is a single line with the string "set_tas_spins", one or more whitespace 38characters, and the number of spins. 39Because the <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment 40is opened, it will silently overrule configuration done before that 41time.</p> 42<p>The DB_ENV->mutex_set_tas_spins method configures operations performed using the specified 43<a href="../api_c/env_class.html">DB_ENV</a> handle, not all operations performed on the underlying 44database environment.</p> 45<p>The DB_ENV->mutex_set_tas_spins method may be called at any time during the life of the 46application.</p> 47<p>The DB_ENV->mutex_set_tas_spins method 48returns a non-zero error value on failure 49and 0 on success. 50</p> 51<b>Parameters</b> <br> 52 <b>tas_spins</b><ul compact><li>The <b>tas_spins</b> parameter is the number of spins test-and-set 53mutexes should execute before blocking.</ul> 54<br> 55<br><b>Errors</b> 56<p>The DB_ENV->mutex_set_tas_spins method 57may fail and return one of the following non-zero errors:</p> 58<br> 59<b>EINVAL</b><ul compact><li>An 60invalid flag value or parameter was specified.</ul> 61<br> 62<hr size=1 noshade> 63<b>Description: DB_ENV->mutex_get_tas_spins</b> 64<p>The DB_ENV->mutex_get_tas_spins method returns the test-and-set spin count.</p> 65<p>The DB_ENV->mutex_get_tas_spins method may be called at any time during the life of the 66application.</p> 67<p>The DB_ENV->mutex_get_tas_spins method 68returns a non-zero error value on failure 69and 0 on success. 70</p> 71<b>Parameters</b> <br> 72 <b>tas_spinsp</b><ul compact><li>The DB_ENV->mutex_get_tas_spins method returns the 73test-and-set spin count in <b>tas_spinsp</b>.</ul> 74<br> 75<hr size=1 noshade> 76<br><b>Class</b> 77<a href="../api_c/env_class.html">DB_ENV</a> 78<br><b>See Also</b> 79<a href="../api_c/env_list.html">Database Environments and Related Methods</a> 80</tt> 81<table width="100%"><tr><td><br></td><td align=right> 82<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> 83</td></tr></table> 84<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 85</body> 86</html> 87
