mirror of
https://github.com/berkeleydb/libdb.git
synced 2024-11-16 17:16:25 +00:00
151 lines
7.1 KiB
HTML
151 lines
7.1 KiB
HTML
<?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>Chapter 22. Berkeley DB Extensions</title>
|
||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||
<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
|
||
<link rel="up" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
|
||
<link rel="prev" href="tcl_faq.html" title="Tcl FAQ" />
|
||
<link rel="next" href="ext_perl.html" title="Using Berkeley DB with Perl" />
|
||
</head>
|
||
<body>
|
||
<div xmlns="" class="navheader">
|
||
<div class="libver">
|
||
<p>Library Version 11.2.5.2</p>
|
||
</div>
|
||
<table width="100%" summary="Navigation header">
|
||
<tr>
|
||
<th colspan="3" align="center">Chapter 22.
|
||
Berkeley DB Extensions
|
||
</th>
|
||
</tr>
|
||
<tr>
|
||
<td width="20%" align="left"><a accesskey="p" href="tcl_faq.html">Prev</a> </td>
|
||
<th width="60%" align="center"> </th>
|
||
<td width="20%" align="right"> <a accesskey="n" href="ext_perl.html">Next</a></td>
|
||
</tr>
|
||
</table>
|
||
<hr />
|
||
</div>
|
||
<div class="chapter" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h2 class="title"><a id="ext"></a>Chapter 22.
|
||
Berkeley DB Extensions
|
||
</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<div class="toc">
|
||
<p>
|
||
<b>Table of Contents</b>
|
||
</p>
|
||
<dl>
|
||
<dt>
|
||
<span class="sect1">
|
||
<a href="ext.html#ext_mod">Using Berkeley DB with Apache</a>
|
||
</span>
|
||
</dt>
|
||
<dt>
|
||
<span class="sect1">
|
||
<a href="ext_perl.html">Using Berkeley DB with Perl</a>
|
||
</span>
|
||
</dt>
|
||
<dt>
|
||
<span class="sect1">
|
||
<a href="ext_php.html">Using Berkeley DB with PHP</a>
|
||
</span>
|
||
</dt>
|
||
</dl>
|
||
</div>
|
||
<div class="sect1" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h2 class="title" style="clear: both"><a id="ext_mod"></a>Using Berkeley DB with Apache</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>A mod_db4 Apache module is included in the Berkeley DB distribution, providing
|
||
a safe framework for running Berkeley DB applications in an Apache 1.3
|
||
environment. Apache natively provides no interface for communication
|
||
between threads or processes, so the mod_db4 module exists to provide
|
||
this communication.</p>
|
||
<p>In general, it is dangerous to run Berkeley DB in a multiprocess system
|
||
without some facility to coordinate database recovery between processes
|
||
sharing the database environment after application or system failure.
|
||
Failure to run recovery after failure can include process hangs and an
|
||
inability to access the database environment. The mod_db4 Apache module
|
||
oversees the proper management of Berkeley DB database environment resources.
|
||
Developers building applications using Berkeley DB as the storage manager
|
||
within an Apache module should employ this technique for proper resource
|
||
management.</p>
|
||
<p>Specifically, mod_db4 provides the following facilities:</p>
|
||
<div class="orderedlist">
|
||
<ol type="1">
|
||
<li>New constructors for <a href="../api_reference/C/env.html" class="olink">DB_ENV</a> and <a href="../api_reference/C/db.html" class="olink">DB</a> handles, which install
|
||
replacement open/close methods.</li>
|
||
<li>Transparent caching of open <a href="../api_reference/C/env.html" class="olink">DB_ENV</a> and <a href="../api_reference/C/db.html" class="olink">DB</a> handles.</li>
|
||
<li>Reference counting on all structures, allowing the module to detect the
|
||
initial opening of any managed database and automatically perform recovery.</li>
|
||
<li>Automatic detection of unexpected failures (segfaults, or a module
|
||
actually calling exit() and avoiding shut down phases), and automatic
|
||
termination of all child processes with open database resources to
|
||
attempt consistency.</li>
|
||
</ol>
|
||
</div>
|
||
<p>mod_db4 is designed to be used as an alternative interface to Berkeley DB. To
|
||
have another Apache module (for example, mod_foo) use mod_db4, do not
|
||
link mod_foo against the Berkeley DB library. In your mod_foo makefile, you
|
||
should:</p>
|
||
<pre class="programlisting">#include "mod_db4_export.h"</pre>
|
||
<p>and add your Apache include directory to your CPPFLAGS.</p>
|
||
<p>In mod_foo, to create a mod_db4 managed <a href="../api_reference/C/env.html" class="olink">DB_ENV</a> handle, use the
|
||
following:</p>
|
||
<pre class="programlisting">int mod_db4_db_env_create(DB_ENV **dbenvp, u_int32_t flags);</pre>
|
||
<p>which takes identical arguments to <a href="../api_reference/C/envcreate.html" class="olink">db_env_create()</a>.</p>
|
||
<p>To create a mod_db4 managed <a href="../api_reference/C/db.html" class="olink">DB</a> handle, use the following:</p>
|
||
<pre class="programlisting">int mod_db4_db_create(DB **dbp, DB_ENV *dbenv, u_int32_t flags);</pre>
|
||
<p>which takes identical arguments to <a href="../api_reference/C/dbcreate.html" class="olink">db_create()</a>.</p>
|
||
<p>Otherwise the API is completely consistent with the standard Berkeley DB
|
||
API.</p>
|
||
<p>The mod_db4 module requires the Berkeley DB library be compiled with C++
|
||
extensions and the MM library. (The MM library provides an abstraction
|
||
layer which allows related processes to share data easily. On systems
|
||
where shared memory or other inter-process communication mechanisms are
|
||
not available, the MM library emulates them using temporary files. MM
|
||
is used in several operating systems to provide shared memory pools to
|
||
Apache modules.)</p>
|
||
<p>To build this apache module, perform the following steps:</p>
|
||
<pre class="programlisting">% ./configure --with-apxs=[path to the apxs utility] \
|
||
--with-db4=[Berkeley DB library installation directory] \
|
||
--with-mm=[libmm installation directory]
|
||
% make
|
||
% make install</pre>
|
||
<p>Post-installation, modules can use this extension via the functions
|
||
documented in $APACHE_INCLUDEDIR/mod_db4_export.h.</p>
|
||
</div>
|
||
</div>
|
||
<div class="navfooter">
|
||
<hr />
|
||
<table width="100%" summary="Navigation footer">
|
||
<tr>
|
||
<td width="40%" align="left"><a accesskey="p" href="tcl_faq.html">Prev</a> </td>
|
||
<td width="20%" align="center"> </td>
|
||
<td width="40%" align="right"> <a accesskey="n" href="ext_perl.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">Tcl FAQ </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top"> Using Berkeley DB with Perl</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</body>
|
||
</html>
|