1<!--$Id: db_set_errcall.so,v 10.10 2002/08/18 21:15:54 bostic Exp $--> 2<!--$Id: env_set_errcall.so,v 10.39 2006/05/17 20:47:46 bostic Exp $--> 3<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 4<!--See the file LICENSE for redistribution information.--> 5<html> 6<head> 7<title>Berkeley DB: Db::set_errcall</title> 8<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 9<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 10</head> 11<body bgcolor=white> 12<table width="100%"><tr valign=top> 13<td> 14<b>Db::set_errcall</b> 15</td> 16<td align=right> 17<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a> 18<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> 19</tr></table> 20<hr size=1 noshade> 21<tt> 22<b><pre> 23#include <db_cxx.h> 24<p> 25void Db::set_errcall(void (*db_errcall_fcn) 26 (const DbEnv *dbenv, const char *errpfx, const char *msg)); 27</pre></b> 28<hr size=1 noshade> 29<b>Description: Db::set_errcall</b> 30When an error occurs in the Berkeley DB library, an exception is thrown or an 31error return value is returned by the interface. In some cases, 32however, the <b>errno</b> value may be insufficient to completely 33describe the cause of the error, especially during initial application 34debugging. 35<p>The <a href="../api_cxx/env_set_errcall.html">DbEnv::set_errcall</a> and Db::set_errcall methods are used to 36enhance the mechanism for reporting error messages to the application. 37In some cases, when an error occurs, Berkeley DB will call 38<b>db_errcall_fcn</b> with additional error information. It is up to 39the <b>db_errcall_fcn</b> function to display the error message in an 40appropriate manner.</p> 41<p>Setting <b>db_errcall_fcn</b> to NULL unconfigures the callback interface.</p> 42<p>Alternatively, you can use the <a href="../api_cxx/env_set_error_stream.html">DbEnv::set_error_stream</a> and 43<a href="../api_cxx/db_set_error_stream.html">Db::set_error_stream</a> methods to display the additional information via 44an output stream, or the <a href="../api_cxx/db_set_errfile.html">Db::set_errfile</a> or 45<a href="../api_cxx/env_set_errfile.html">DbEnv::set_errfile</a> methods to display the additional information via a C 46library FILE *. You should not mix these approaches.</p> 47<p>This error-logging enhancement does not slow performance or significantly 48increase application size, and may be run during normal operation as well 49as during application debugging.</p> 50<p>For <a href="../api_cxx/db_class.html">Db</a> handles opened inside of Berkeley DB environments, calling the 51Db::set_errcall method affects the entire environment and is equivalent to calling 52the <a href="../api_cxx/env_set_errcall.html">DbEnv::set_errcall</a> method.</p> 53<p>The Db::set_errcall method configures operations performed using the specified 54<a href="../api_cxx/db_class.html">Db</a> handle, not all operations performed on the underlying 55database.</p> 56<p>The Db::set_errcall method may be called at any time during the life of the 57application.</p> 58<b>Parameters</b> <br> 59 <b>db_errcall_fcn</b><ul compact><li>The <b>db_errcall_fcn</b> parameter is the application-specified error 60reporting function. The function takes three parameters: 61<br> 62<b><b>dbenv</b></b><ul compact><li>The <b>dbenv</b> parameter is the enclosing database environment.</ul> 63<b><b>errpfx</b></b><ul compact><li>The <b>errpfx</b> parameter is the prefix string (as previously set by 64<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> 65<b><b>msg</b></b><ul compact><li>The <b>msg</b> parameter is the error message string.</ul> 66<br> 67<p>Berkeley DB is not re-entrant. Callback functions should not attempt to make 68library calls (for example, to release locks or close open handles). 69Re-entering Berkeley DB is not guaranteed to work correctly, and the results 70are undefined.</p></ul> 71<br> 72<hr size=1 noshade> 73<br><b>Class</b> 74<a href="../api_cxx/db_class.html">Db</a> 75<br><b>See Also</b> 76<a href="../api_cxx/db_list.html">Databases and Related Methods</a> 77</tt> 78<table width="100%"><tr><td><br></td><td align=right> 79<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> 80</td></tr></table> 81<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 82</body> 83</html> 84
