<!--$Id: memp_set_clear_len.so,v 10.18 2005/11/30 19:46:21 bostic Exp $--> <!--Copyright (c) 1997,2007 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DbMpoolFile::set_clear_len</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> <h3>DbMpoolFile::set_clear_len</h3> </td> <td align=right> <a href="../../db46-devel-4.6.21/api_cxx/api_core.html"><img src="../../db46-devel-4.6.21/images/api.gif" alt="API"></a> <a href="../../db46-devel-4.6.21/ref/toc.html"><img src="../../db46-devel-4.6.21/images/ref.gif" alt="Ref"></a></td> </tr></table> <hr size=1 noshade> <tt> <h3><pre> #include <db_cxx.h> <p> int DbMpoolFile::set(u_int32_t len); <p> int DbMpoolFile::get_clear_len(u_int32_t *lenp); </pre></h3> <hr size=1 noshade> <h3>Description: DbMpoolFile::set_clear_len</h3> <p>The DbMpoolFile::set_clear_len 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 href="../../db46-devel-4.6.21/api_cxx/memp_fget.html#DB_MPOOL_CREATE">DB_MPOOL_CREATE</a> or <a href="../../db46-devel-4.6.21/api_cxx/memp_fget.html#DB_MPOOL_NEW">DB_MPOOL_NEW</a> flags being specified to <a href="../../db46-devel-4.6.21/api_cxx/memp_fget.html">DbMpoolFile::get</a>. If no clear length is specified, the entire page is cleared when it is created.</p> <p>The DbMpoolFile::set_clear_len method configures a file in the memory pool, not only operations performed using the specified <a href="../../db46-devel-4.6.21/api_cxx/mempfile_class.html">DbMpoolFile</a> handle.</p> <p>The DbMpoolFile::set_clear_len method may not be called after the <a href="../../db46-devel-4.6.21/api_cxx/memp_fopen.html">DbMpoolFile::open</a> method is called. If the file is already open in the memory pool when <a href="../../db46-devel-4.6.21/api_cxx/memp_fopen.html">DbMpoolFile::open</a> is called, the information specified to DbMpoolFile::set_clear_len must be consistent with the existing file or an error will be returned. </p> <p>The DbMpoolFile::set_clear_len 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> <h3>Parameters</h3> <dl compact> <dt><b>len</b><dd>The <b>len</b> 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. </dl> <hr size=1 noshade> <h3>Description: DbMpoolFile::get_clear_len</h3> <p>The DbMpoolFile::get_clear_len method returns the bytes to be cleared.</p> <p>The DbMpoolFile::get_clear_len method may be called at any time during the life of the application.</p> <p>The DbMpoolFile::get_clear_len 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> <h3>Parameters</h3> <dl compact> <dt><b>lenp</b><dd>The DbMpoolFile::get_clear_len method returns the bytes to be cleared in <b>lenp</b>. </dl> <hr size=1 noshade> <h3>Class</h3> <a href="../../db46-devel-4.6.21/api_cxx/env_class.html">DbEnv</a>, <a href="../../db46-devel-4.6.21/api_cxx/mempfile_class.html">DbMpoolFile</a> <h3>See Also</h3> <a href="../../db46-devel-4.6.21/api_cxx/memp_list.html">Memory Pools and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db46-devel-4.6.21/api_cxx/api_core.html"><img src="../../db46-devel-4.6.21/images/api.gif" alt="API"></a><a href="../../db46-devel-4.6.21/ref/toc.html"><img src="../../db46-devel-4.6.21/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2007 Oracle. All rights reserved.</font> </body> </html>