Edit File - File Manager

Edit File: mutex_set_align.html

<html>
<head>
<title>Berkeley DB: DbEnv::mutex_set_align</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>
DbEnv::mutex_set_align
</td>
<td align=right>
<a href="../../db4-devel-4.7.25/api_cxx/api_core.html"><img src="../../db4-devel-4.7.25/images/api.gif" alt="API"></a>
<a href="../../db4-devel-4.7.25/ref/toc.html"><img src="../../db4-devel-4.7.25/images/ref.gif" alt="Ref"></a></td>
</tr></table>
<hr size=1 noshade>
<tt>
<pre>
#include &lt;db_cxx.h&gt;

int
DbEnv::mutex_set_align(u_int32_t align);

int
DbEnv::mutex_get_align(u_int32_t *alignp);
</pre>
<hr size=1 noshade>
Description: DbEnv::mutex_set_align
Set the mutex alignment, in bytes.
It is sometimes advantageous to align mutexes on specific byte
boundaries in order to minimize cache line collisions. The
DbEnv::mutex_set_align method specifies an alignment for mutexes allocated
by Berkeley DB.
The database environment's mutex alignment may also be configured using the
environment's <a href="../../db4-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 "mutex_set_align", one or more whitespace
characters, and the mutex alignment in bytes.
Because the <a href="../../db4-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.
The DbEnv::mutex_set_align method configures a database environment, not only operations
performed using the specified <a href="../../db4-devel-4.7.25/api_cxx/env_class.html">DbEnv</a> handle.
The DbEnv::mutex_set_align method may not be called after the <a href="../../db4-devel-4.7.25/api_cxx/env_open.html">DbEnv::open</a> method is
called.
If the database environment already exists when
<a href="../../db4-devel-4.7.25/api_cxx/env_open.html">DbEnv::open</a> is called, the information specified to DbEnv::mutex_set_align
will be ignored.

The DbEnv::mutex_set_align 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.

Parameters 
 align<ul compact><li>The align parameter is the mutex alignment, in bytes. The mutex
alignment must be a power-of-two.</ul>
 
 Errors
The DbEnv::mutex_set_align method
may fail and throw
<a href="../../db4-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:
 
EINVAL<ul compact><li>An
invalid flag value or parameter was specified.</ul>
 
<hr size=1 noshade>
Description: DbEnv::mutex_get_align
The DbEnv::mutex_get_align method returns the mutex alignment, in bytes.
The DbEnv::mutex_get_align method may be called at any time during the life of the
application.
The DbEnv::mutex_get_align 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.

Parameters 
 alignp<ul compact><li>The DbEnv::mutex_get_align method returns the
mutex alignment, in bytes in alignp.</ul>
 
<hr size=1 noshade>
 Class
<a href="../../db4-devel-4.7.25/api_cxx/env_class.html">DbEnv</a>
 See Also
<a href="../../db4-devel-4.7.25/api_cxx/env_list.html">Database Environments and Related Methods</a>
</tt>
<table width="100%"><tr><td> </td><td align=right>
<a href="../../db4-devel-4.7.25/api_cxx/api_core.html"><img src="../../db4-devel-4.7.25/images/api.gif" alt="API"></a><a href="../../db4-devel-4.7.25/ref/toc.html"><img src="../../db4-devel-4.7.25/images/ref.gif" alt="Ref"></a>
</td></tr></table>
Copyright (c) 1996,2008 Oracle. All rights reserved.
</body>
</html>

Back to File Manager