1<!--$Id: env_set_errcall.so,v 10.39 2006/05/17 20:47:46 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::set_errcall</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::set_errcall</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> 24void DbEnv::set_errcall(void (*db_errcall_fcn) 25 (const Dbenv *dbenv, const char *errpfx, const char *msg)); 26</pre></b> 27<hr size=1 noshade> 28<b>Description: DbEnv::set_errcall</b> 29When an error occurs in the Berkeley DB library, an exception is thrown or an 30error return value is returned by the interface. In some cases, 31however, the <b>errno</b> value may be insufficient to completely 32describe the cause of the error, especially during initial application 33debugging. 34<p>The DbEnv::set_errcall and <a href="/api_cxx/db_set_errcall.html">Db::set_errcall</a> methods are used to 35enhance the mechanism for reporting error messages to the application. 36In some cases, when an error occurs, Berkeley DB will call 37<b>db_errcall_fcn</b> with additional error information. It is up to 38the <b>db_errcall_fcn</b> function to display the error message in an 39appropriate manner.</p> 40<p>Setting <b>db_errcall_fcn</b> to NULL unconfigures the callback interface.</p> 41<p>Alternatively, you can use the <a href="/api_cxx/env_set_error_stream.html">DbEnv::set_error_stream</a> and 42<a href="/api_cxx/db_set_error_stream.html">Db::set_error_stream</a> methods to display the additional information via 43an output stream, or the <a href="/api_cxx/db_set_errfile.html">Db::set_errfile</a> or 44<a href="/api_cxx/env_set_errfile.html">DbEnv::set_errfile</a> methods to display the additional information via a C 45library FILE *. You should not mix these approaches.</p> 46<p>This error-logging enhancement does not slow performance or significantly 47increase application size, and may be run during normal operation as well 48as during application debugging.</p> 49<p>The DbEnv::set_errcall method configures operations performed using the specified 50<a href="/api_cxx/env_class.html">DbEnv</a> handle, not all operations performed on the underlying 51database environment.</p> 52<p>The DbEnv::set_errcall method may be called at any time during the life of the 53application.</p> 54<b>Parameters</b> <br> 55 <b>db_errcall_fcn</b><ul compact><li>The <b>db_errcall_fcn</b> parameter is the application-specified error 56reporting function. The function takes three parameters: 57<br> 58<b><b>dbenv</b></b><ul compact><li>The <b>dbenv</b> parameter is the enclosing database environment.</ul> 59<b><b>errpfx</b></b><ul compact><li>The <b>errpfx</b> parameter is the prefix string (as previously set by 60<a href="/api_cxx/db_set_errpfx.html">Db::set_errpfx</a> or <a href="/api_cxx/env_set_errpfx.html">DbEnv::set_errpfx</a>).</ul> 61<b><b>msg</b></b><ul compact><li>The <b>msg</b> parameter is the error message string.</ul> 62<br> 63<p>Berkeley DB is not re-entrant. Callback functions should not attempt to make 64library calls (for example, to release locks or close open handles). 65Re-entering Berkeley DB is not guaranteed to work correctly, and the results 66are undefined.</p></ul> 67<br> 68<hr size=1 noshade> 69<br><b>Class</b> 70<a href="/api_cxx/env_class.html">DbEnv</a> 71<br><b>See Also</b> 72<a href="/api_cxx/env_list.html">Database Environments and Related Methods</a> 73</tt> 74<table width="100%"><tr><td><br></td><td align=right> 75<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> 76</td></tr></table> 77<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 78</body> 79</html> 80
