1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>DbEnv::close()</title> 7 <link rel="stylesheet" href="apiReference.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> 10 <link rel="up" href="env.html" title="Chapter 5. The DbEnv Handle" /> 11 <link rel="prev" href="envadd_data_dir.html" title="DbEnv::add_data_dir()" /> 12 <link rel="next" href="envcreate.html" title="DbEnv" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">DbEnv::close()</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="envadd_data_dir.html">Prev</a> </td> 22 <th width="60%" align="center">Chapter 5. 23 The DbEnv Handle 24 </th> 25 <td width="20%" align="right"> <a accesskey="n" href="envcreate.html">Next</a></td> 26 </tr> 27 </table> 28 <hr /> 29 </div> 30 <div class="sect1" lang="en" xml:lang="en"> 31 <div class="titlepage"> 32 <div> 33 <div> 34 <h2 class="title" style="clear: both"><a id="envclose"></a>DbEnv::close()</h2> 35 </div> 36 </div> 37 </div> 38 <pre class="programlisting">#include <db_cxx.h> 39 40DbEnv::close(u_int32_t flags);</pre> 41 <p> 42 The <code class="methodname">DbEnv::close()</code> method closes the Berkeley DB environment, 43 freeing any allocated resources and closing any underlying subsystems. 44 </p> 45 <p> 46 The <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle should 47 not be closed while any other handle that refers to it is not yet 48 closed; for example, database environment handles must not be closed 49 while database handles remain open, or transactions in the environment 50 have not yet been committed or aborted. Specifically, this includes the 51 <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a>, 52 <a class="link" href="dbc.html" title="Chapter 3. The Dbc Handle">Dbc</a>, 53 <a class="link" href="txn.html" title="Chapter 13. The DbTxn Handle">DbTxn</a>, 54 <a class="link" href="logc.html" title="The DbLogc Handle">DbLogc</a> and 55 <a class="link" href="memp.html" title="Chapter 9. The DbMpoolFile Handle">DbMpoolFile</a> handles. 56 </p> 57 <p> 58 Where the environment was initialized with the 59 <a class="link" href="envopen.html#envopen_DB_INIT_LOCK">DB_INIT_LOCK</a> flag, 60 calling <code class="methodname">DbEnv::close()</code> does not release any locks still held by the 61 closing process, providing functionality for long-lived locks. 62 Processes that want to have all their locks released can do so by 63 issuing the appropriate <a class="xref" href="lockvec.html" title="DbEnv::lock_vec()">DbEnv::lock_vec()</a> call. 64 </p> 65 <p> 66 Where the environment was initialized with the 67 <a class="link" href="envopen.html#envopen_DB_INIT_MPOOL">DB_INIT_MPOOL</a> flag, 68 calling <code class="methodname">DbEnv::close()</code> implies calls to 69 <a class="xref" href="mempfclose.html" title="DbMpoolFile::close()">DbMpoolFile::close()</a> for any 70 remaining open files in the memory pool that were returned to this 71 process by calls to <a class="xref" href="mempfopen.html" title="DbMpoolFile::open()">DbMpoolFile::open()</a>. It does 72 not imply a call to <a class="xref" href="mempfsync.html" title="DbMpoolFile::sync()">DbMpoolFile::sync()</a> for those 73 files. 74 </p> 75 <p> 76 Where the environment was initialized with the 77 <a class="link" href="envopen.html#envopen_DB_INIT_TXN">DB_INIT_TXN</a> flag, 78 calling <code class="methodname">DbEnv::close()</code> aborts any unresolved transactions. 79 Applications should not depend on this behavior for transactions 80 involving Berkeley DB databases; all such transactions should be 81 explicitly resolved. The problem with depending on this semantic is 82 that aborting an unresolved transaction involving database operations 83 requires a database handle. Because the database handles should have 84 been closed before calling <code class="methodname">DbEnv::close()</code>, it will not be possible 85 to abort the transaction, and recovery will have to be run on the 86 Berkeley DB environment before further operations are done. 87 </p> 88 <p> 89 Where log cursors were created using the 90 <a class="xref" href="logcursor.html" title="DbEnv::log_cursor()">DbEnv::log_cursor()</a> method, 91 calling <code class="methodname">DbEnv::close()</code> does not imply closing those cursors. 92 </p> 93 <p> 94 In multithreaded applications, only a single thread may call the 95 <code class="methodname">DbEnv::close()</code> method. 96 </p> 97 <p> 98 After <code class="methodname">DbEnv::close()</code> has been called, regardless of its return, the 99 Berkeley DB environment handle may not be accessed again. 100 </p> 101 <p> 102 The <code class="methodname">DbEnv::close()</code> <span> 103 104 <span> 105 method either returns a non-zero error value or throws an 106 exception that encapsulates a non-zero error value on 107 failure, and returns 0 on success. 108 </span> 109 </span> 110 </p> 111 <div class="sect2" lang="en" xml:lang="en"> 112 <div class="titlepage"> 113 <div> 114 <div> 115 <h3 class="title"><a id="id1662940"></a>Parameters</h3> 116 </div> 117 </div> 118 </div> 119 <div class="sect3" lang="en" xml:lang="en"> 120 <div class="titlepage"> 121 <div> 122 <div> 123 <h4 class="title"><a id="id1662944"></a>flags</h4> 124 </div> 125 </div> 126 </div> 127 <p> 128 The <span class="bold"><strong>flags</strong></span> parameter is currently 129 unused, and must be set to 0. 130 </p> 131 </div> 132 </div> 133 <div class="sect2" lang="en" xml:lang="en"> 134 <div class="titlepage"> 135 <div> 136 <div> 137 <h3 class="title"><a id="id1663093"></a>Class</h3> 138 </div> 139 </div> 140 </div> 141 <p> 142 <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> 143 </p> 144 </div> 145 <div class="sect2" lang="en" xml:lang="en"> 146 <div class="titlepage"> 147 <div> 148 <div> 149 <h3 class="title"><a id="id1662241"></a>See Also</h3> 150 </div> 151 </div> 152 </div> 153 <p> 154 <a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a> 155 </p> 156 </div> 157 </div> 158 <div class="navfooter"> 159 <hr /> 160 <table width="100%" summary="Navigation footer"> 161 <tr> 162 <td width="40%" align="left"><a accesskey="p" href="envadd_data_dir.html">Prev</a> </td> 163 <td width="20%" align="center"> 164 <a accesskey="u" href="env.html">Up</a> 165 </td> 166 <td width="40%" align="right"> <a accesskey="n" href="envcreate.html">Next</a></td> 167 </tr> 168 <tr> 169 <td width="40%" align="left" valign="top">DbEnv::add_data_dir() </td> 170 <td width="20%" align="center"> 171 <a accesskey="h" href="index.html">Home</a> 172 </td> 173 <td width="40%" align="right" valign="top"> DbEnv</td> 174 </tr> 175 </table> 176 </div> 177 </body> 178</html> 179