libdb/docs/api_reference/C/mempset_clear_len.html
2012-11-14 16:35:20 -05:00

145 lines
6.2 KiB
HTML
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<?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>DB_MPOOLFILE-&gt;set_clear_len()</title>
<link rel="stylesheet" href="apiReference.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
<link rel="start" href="index.html" title="Berkeley DB C API Reference" />
<link rel="up" href="memp.html" title="Chapter 8.  The DB_MPOOLFILE Handle" />
<link rel="prev" href="mempget_priority.html" title="DB_MPOOLFILE-&gt;get_priority()" />
<link rel="next" href="mempset_fileid.html" title="DB_MPOOLFILE-&gt;set_fileid()" />
</head>
<body>
<div xmlns="" class="navheader">
<div class="libver">
<p>Library Version 11.2.5.3</p>
</div>
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DB_MPOOLFILE-&gt;set_clear_len()</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="mempget_priority.html">Prev</a> </td>
<th width="60%" align="center">Chapter 8. 
The DB_MPOOLFILE Handle
</th>
<td width="20%" align="right"> <a accesskey="n" href="mempset_fileid.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="mempset_clear_len"></a>DB_MPOOLFILE-&gt;set_clear_len()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include &lt;db.h&gt;
int
DB_MPOOLFILE-&gt;set_clear_len(DB_MPOOLFILE *mpf, u_int32_t len); </pre>
<p>
The <code class="methodname">DB_MPOOLFILE-&gt;set_clear_len()</code> method sets the number of initial
bytes in a page that should be set to nul when the page is created as
a result of the
<a class="link" href="mempfget.html#mpoolfget_DB_MPOOL_CREATE">DB_MPOOL_CREATE</a>
or <a class="link" href="mempfget.html#mpoolfget_DB_MPOOL_NEW">DB_MPOOL_NEW</a>
flags specified to <a class="xref" href="mempfget.html" title="DB_MPOOLFILE-&gt;get()">DB_MPOOLFILE-&gt;get()</a>. If no
clear length is specified, the entire page is cleared when it is
created.
</p>
<p>
The <code class="methodname">DB_MPOOLFILE-&gt;set_clear_len()</code> method configures a file in the
cache, not only operations performed using the specified
<a class="link" href="memp.html" title="Chapter 8.  The DB_MPOOLFILE Handle">DB_MPOOLFILE</a> handle.
</p>
<p>
The <code class="methodname">DB_MPOOLFILE-&gt;set_clear_len()</code> method may not be called after the
<a class="xref" href="mempfopen.html" title="DB_MPOOLFILE-&gt;open()">DB_MPOOLFILE-&gt;open()</a>
method is called. If the file is already open in the cache when
<a class="xref" href="mempfopen.html" title="DB_MPOOLFILE-&gt;open()">DB_MPOOLFILE-&gt;open()</a> is
called, the information specified to <code class="methodname">DB_MPOOLFILE-&gt;set_clear_len()</code>
must be consistent with the existing file or an error will be returned.
</p>
<p>
The <code class="methodname">DB_MPOOLFILE-&gt;set_clear_len()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp61534368"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp61533720"></a>len</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>len</strong></span> parameter is the number of
initial bytes in a page that should be set to nul when the page is
created. A value of 0 results in the entire page being set to nul
bytes.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp61527384"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5.  The DB_ENV Handle">DB_ENV</a>, <a class="link" href="memp.html" title="Chapter 8.  The DB_MPOOLFILE Handle">DB_MPOOLFILE</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp61525376"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="memp.html#memplist" title="Memory Pools and Related Methods">Memory Pools and Related Methods</a>
</p>
</div>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="mempget_priority.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="memp.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="mempset_fileid.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">DB_MPOOLFILE-&gt;get_priority() </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> DB_MPOOLFILE-&gt;set_fileid()</td>
</tr>
</table>
</div>
</body>
</html>