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: DB_ENV->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>DB_ENV->close</b> 14</td> 15<td align=right> 16<a href="/api_c/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.h> 23<p> 24int 25DB_ENV->close(DB_ENV *dbenv, u_int32_t flags); 26</pre></b> 27<hr size=1 noshade> 28<b>Description: DB_ENV->close</b> 29<p>The DB_ENV->close method closes the Berkeley DB environment, freeing any 30allocated resources and closing any underlying subsystems.</p> 31<p>The <a href="/api_c/env_class.html">DB_ENV</a> handle should not be closed while any other handle 32that refers to it is not yet closed; for example, database environment 33handles must not be closed while database handles remain open, or 34transactions in the environment have not yet been committed or aborted. 35Specifically, this includes <a href="/api_c/db_class.html">DB</a>, <a href="/api_c/dbc_class.html">DBC</a>, <a href="/api_c/txn_class.html">DB_TXN</a>, 36<a href="/api_c/logc_class.html">DB_LOGC</a> and <a href="/api_c/mempfile_class.html">DB_MPOOLFILE</a> handles.</p> 37<p>Where the environment was initialized with the <a href="/api_c/env_open.html#DB_INIT_LOCK">DB_INIT_LOCK</a> 38flag, calling DB_ENV->close does not release any locks still held 39by the closing process, providing functionality for long-lived locks. 40Processes that want to have all their locks released can do so by 41issuing the appropriate <a href="/api_c/lock_vec.html">DB_ENV->lock_vec</a> call.</p> 42<p>Where the environment was initialized with the <a href="/api_c/env_open.html#DB_INIT_MPOOL">DB_INIT_MPOOL</a> 43flag, calling DB_ENV->close implies calls to <a href="/api_c/memp_fclose.html">DB_MPOOLFILE->close</a> for 44any remaining open files in the memory pool that were returned to this 45process by calls to <a href="/api_c/memp_fopen.html">DB_MPOOLFILE->open</a>. It does not imply a call to 46<a href="/api_c/memp_fsync.html">DB_MPOOLFILE->sync</a> for those files.</p> 47<p>Where the environment was initialized with the <a href="/api_c/env_open.html#DB_INIT_TXN">DB_INIT_TXN</a> flag, 48calling DB_ENV->close aborts any unresolved transactions. 49Applications should not depend on this behavior for transactions 50involving Berkeley DB databases; all such transactions should be explicitly 51resolved. The problem with depending on this semantic is that aborting 52an unresolved transaction involving database operations requires a 53database handle. Because the database handles should have been closed before 54calling DB_ENV->close, it will not be possible to abort the 55transaction, and recovery will have to be run on the Berkeley DB environment 56before further operations are done.</p> 57<p>Where log cursors were created using the <a href="/api_c/log_cursor.html">DB_ENV->log_cursor</a> method, calling 58DB_ENV->close does not imply closing those cursors.</p> 59<p>In multithreaded applications, only a single thread may call 60DB_ENV->close.</p> 61<p>After DB_ENV->close has been called, regardless of its return, the 62Berkeley DB environment handle may not be accessed again.</p> 63<p>The DB_ENV->close method 64returns a non-zero error value on failure 65and 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_c/env_class.html">DB_ENV</a> 73<br><b>See Also</b> 74<a href="/api_c/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_c/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
