2011-09-13 17:44:24 +00:00
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Chapter 15. Programmer Notes</title>
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<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="prev" href="apprec_config.html" title="Application configuration" />
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<p>Library Version 11.2.5.2</p>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Chapter 15.
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Programmer Notes
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</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="apprec_config.html">Prev</a> </td>
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<th width="60%" align="center"> </th>
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<td width="20%" align="right"> <a accesskey="n" href="program_errorret.html">Next</a></td>
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<div class="chapter" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title"><a id="program"></a>Chapter 15.
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Programmer Notes
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</h2>
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</div>
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</div>
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</div>
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<div class="toc">
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<p>
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<b>Table of Contents</b>
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</p>
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<dl>
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<dt>
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<span class="sect1">
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<a href="program.html#program_appsignals">Signal handling</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_errorret.html">Error returns to applications</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_environ.html">Environment variables</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_mt.html">Multithreaded applications</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_scope.html">Berkeley DB handles</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_namespace.html">Name spaces</a>
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</span>
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</dt>
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<dd>
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<dl>
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<dt>
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<span class="sect2">
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2011-12-20 00:07:10 +00:00
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<a href="program_namespace.html#id3968888">C Language Name Space</a>
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2011-09-13 17:44:24 +00:00
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</span>
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</dt>
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<dt>
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<span class="sect2">
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2011-12-20 00:07:10 +00:00
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<a href="program_namespace.html#id3968318">Filesystem Name Space</a>
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2011-09-13 17:44:24 +00:00
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</span>
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</dt>
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</dl>
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</dd>
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<dt>
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<span class="sect1">
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<a href="program_ram.html">Memory-only or Flash configurations</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_cache.html">Disk drive caches</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_copy.html">Copying or moving databases</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_compatible.html">Compatibility with historic UNIX interfaces</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_runtime.html">Run-time configuration</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="program_perfmon.html">Performance Event Monitoring</a>
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</span>
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</dt>
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<dd>
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<dl>
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<dt>
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<span class="sect2">
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<a href="program_perfmon.html#program_perfmon_dtrace">Using the DTrace Provider</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="program_perfmon.html#program_perfmon_stap">Using SystemTap</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="program_perfmon.html#program_perfmon_examples">Example Scripts</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="program_perfmon.html#program_perfmon_probes">Performance Events Reference</a>
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</span>
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</dt>
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</dl>
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</dd>
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<dt>
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<span class="sect1">
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<a href="program_faq.html">Programmer notes FAQ</a>
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</span>
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</dt>
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</dl>
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="program_appsignals"></a>Signal handling</h2>
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</div>
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</div>
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</div>
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<p>When applications using Berkeley DB receive signals, it is important that they
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exit gracefully, discarding any Berkeley DB locks that they may hold. This is
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normally done by setting a flag when a signal arrives and then checking
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for that flag periodically within the application. Because Berkeley DB is not
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re-entrant, the signal handler should not attempt to release locks and/or
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close the database handles itself. Re-entering Berkeley DB is not guaranteed to
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work correctly, and the results are undefined.</p>
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<p>If an application exits holding a lock, the situation is no different
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than if the application crashed, and all applications participating in
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the database environment must be shut down, and then recovery must be
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performed. If this is not done, databases may be left in an
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inconsistent state, or locks the application held may cause unresolvable
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deadlocks inside the environment, causing applications to hang.</p>
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<p>Berkeley DB restarts all system calls interrupted by signals, that is, any
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underlying system calls that return failure with errno set to EINTR will
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be restarted rather than failing.</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="apprec_config.html">Prev</a> </td>
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<td width="20%" align="center"> </td>
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<td width="40%" align="right"> <a accesskey="n" href="program_errorret.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Application configuration </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Error returns to applications</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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