<!--$Id: mutex_set_tas_spins.so,v 10.30 2005/07/20 16:34:01 bostic Exp $--> <!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DbEnv::mutex_set_tas_spins</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <table width="100%"><tr valign=top> <td> <b>DbEnv::mutex_set_tas_spins</b> </td> <td align=right> <a href="../../db47-devel-4.7.25/api_cxx/api_core.html"><img src="../../db47-devel-4.7.25/images/api.gif" alt="API"></a> <a href="../../db47-devel-4.7.25/ref/toc.html"><img src="../../db47-devel-4.7.25/images/ref.gif" alt="Ref"></a></td> </tr></table> <hr size=1 noshade> <tt> <b><pre> #include <db_cxx.h> <p> int DbEnv::mutex_set_tas_spins(u_int32_t tas_spins); <p> int DbEnv::mutex_get_tas_spins(u_int32_t *, tas_spinsp); </pre></b> <hr size=1 noshade> <b>Description: DbEnv::mutex_set_tas_spins</b> <p>Specify that test-and-set mutexes should spin <b>tas_spins</b> 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="../../db47-devel-4.7.25/ref/env/db_config.html#DB_CONFIG">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="../../db47-devel-4.7.25/ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment is opened, it will silently overrule configuration done before that time.</p> <p>The DbEnv::mutex_set_tas_spins method configures operations performed using the specified <a href="../../db47-devel-4.7.25/api_cxx/env_class.html">DbEnv</a> handle, not all operations performed on the underlying database environment.</p> <p>The DbEnv::mutex_set_tas_spins method may be called at any time during the life of the application.</p> <p>The DbEnv::mutex_set_tas_spins 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. </p> <b>Parameters</b> <br> <b>tas_spins</b><ul compact><li>The <b>tas_spins</b> parameter is the number of spins test-and-set mutexes should execute before blocking.</ul> <br> <br><b>Errors</b> <p>The DbEnv::mutex_set_tas_spins method may fail and throw <a href="../../db47-devel-4.7.25/api_cxx/except_class.html">DbException</a>, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:</p> <br> <b>EINVAL</b><ul compact><li>An invalid flag value or parameter was specified.</ul> <br> <hr size=1 noshade> <b>Description: DbEnv::mutex_get_tas_spins</b> <p>The DbEnv::mutex_get_tas_spins method returns the test-and-set spin count.</p> <p>The DbEnv::mutex_get_tas_spins method may be called at any time during the life of the application.</p> <p>The DbEnv::mutex_get_tas_spins 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. </p> <b>Parameters</b> <br> <b>tas_spinsp</b><ul compact><li>The DbEnv::mutex_get_tas_spins method returns the test-and-set spin count in <b>tas_spinsp</b>.</ul> <br> <hr size=1 noshade> <br><b>Class</b> <a href="../../db47-devel-4.7.25/api_cxx/env_class.html">DbEnv</a> <br><b>See Also</b> <a href="../../db47-devel-4.7.25/api_cxx/env_list.html">Database Environments and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db47-devel-4.7.25/api_cxx/api_core.html"><img src="../../db47-devel-4.7.25/images/api.gif" alt="API"></a><a href="../../db47-devel-4.7.25/ref/toc.html"><img src="../../db47-devel-4.7.25/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> </body> </html>