1<!--$Id: env_close.so,v 10.38 2004/08/13 03:38:56 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: DbEnv::close</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>DbEnv::close</b> 14</td> 15<td align=right> 16<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a> 17<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db_cxx.h> 23<p> 24DbEnv::close(u_int32_t flags); 25</pre></b> 26<hr size=1 noshade> 27<b>Description: DbEnv::close</b> 28<p>The DbEnv::close method closes the Berkeley DB environment, freeing any 29allocated resources and closing any underlying subsystems.</p> 30<p>The <a href="../api_cxx/env_class.html">DbEnv</a> handle should not be closed while any other handle 31that refers to it is not yet closed; for example, database environment 32handles must not be closed while database handles remain open, or 33transactions in the environment have not yet been committed or aborted. 34Specifically, this includes <a href="../api_cxx/db_class.html">Db</a>, <a href="../api_cxx/dbc_class.html">Dbc</a>, <a href="../api_cxx/txn_class.html">DbTxn</a>, 35<a href="../api_cxx/logc_class.html">DbLogc</a> and <a href="../api_cxx/mempfile_class.html">DbMpoolFile</a> handles.</p> 36<p>Where the environment was initialized with the <a href="../api_cxx/env_open.html#DB_INIT_LOCK">DB_INIT_LOCK</a> 37flag, calling DbEnv::close does not release any locks still held 38by the closing process, providing functionality for long-lived locks. 39Processes that want to have all their locks released can do so by 40issuing the appropriate <a href="../api_cxx/lock_vec.html">DbEnv::lock_vec</a> call.</p> 41<p>Where the environment was initialized with the <a href="../api_cxx/env_open.html#DB_INIT_MPOOL">DB_INIT_MPOOL</a> 42flag, calling DbEnv::close implies calls to <a href="../api_cxx/memp_fclose.html">DbMpoolFile::close</a> for 43any remaining open files in the memory pool that were returned to this 44process by calls to <a href="../api_cxx/memp_fopen.html">DbMpoolFile::open</a>. It does not imply a call to 45<a href="../api_cxx/memp_fsync.html">DbMpoolFile::sync</a> for those files.</p> 46<p>Where the environment was initialized with the <a href="../api_cxx/env_open.html#DB_INIT_TXN">DB_INIT_TXN</a> flag, 47calling DbEnv::close aborts any unresolved transactions. 48Applications should not depend on this behavior for transactions 49involving Berkeley DB databases; all such transactions should be explicitly 50resolved. The problem with depending on this semantic is that aborting 51an unresolved transaction involving database operations requires a 52database handle. Because the database handles should have been closed before 53calling DbEnv::close, it will not be possible to abort the 54transaction, and recovery will have to be run on the Berkeley DB environment 55before further operations are done.</p> 56<p>Where log cursors were created using the <a href="../api_cxx/log_cursor.html">DbEnv::log_cursor</a> method, calling 57DbEnv::close does not imply closing those cursors.</p> 58<p>In multithreaded applications, only a single thread may call 59DbEnv::close.</p> 60<p>After DbEnv::close has been called, regardless of its return, the 61Berkeley DB environment handle may not be accessed again.</p> 62<p>The DbEnv::close method 63either returns a non-zero error value 64or throws an exception that encapsulates a non-zero error value on 65failure, and returns 0 on success. 66</p> 67<b>Parameters</b> <br> 68 <b>flags</b><ul compact><li>The <b>flags</b> parameter is currently unused, and must be set to 0.</ul> 69<br> 70<hr size=1 noshade> 71<br><b>Class</b> 72<a href="../api_cxx/env_class.html">DbEnv</a> 73<br><b>See Also</b> 74<a href="../api_cxx/env_list.html">Database Environments and Related Methods</a> 75</tt> 76<table width="100%"><tr><td><br></td><td align=right> 77<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> 78</td></tr></table> 79<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 80</body> 81</html> 82