1<!--$Id: env_event_notify.so,v 10.13 2007/04/05 20:37:29 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->set_event_notify</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->set_event_notify</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->set_event_notify(DB_ENV *dbenv, 26 void (*db_event_fcn)(DB_ENV *dbenv, u_int32_t event, void *event_info)); 27</pre></b> 28<hr size=1 noshade> 29<b>Description: DB_ENV->set_event_notify</b> 30<p>The DB_ENV->set_event_notify method configures a callback function which 31is called to notify the process of specific Berkeley DB events.</p> 32<p>The DB_ENV->set_event_notify method configures operations performed using the specified 33<a href="/api_c/env_class.html">DB_ENV</a> handle, not all operations performed on the underlying 34database environment.</p> 35<p>The DB_ENV->set_event_notify method may be called at any time during the life of the 36application.</p> 37<p>The DB_ENV->set_event_notify method 38returns a non-zero error value on failure 39and 0 on success. 40</p> 41<b>Parameters</b> <br> 42 <b>db_event_fcn</b><ul compact><li>The <b>db_event_fcn</b> parameter is the application's event 43notification function. The function takes three parameters: 44<br> 45<b>dbenv</b><ul compact><li>The <b>dbenv</b> parameter is the enclosing database environment handle.</ul> 46<b>event</b><ul compact><li>The <b>event</b> parameter is one of the following values:</ul> 47<br> 48<b><a name="DB_EVENT_PANIC">DB_EVENT_PANIC</a></b><ul compact><li>Errors can occur in the Berkeley DB library where the only solution is to shut 49down the application and run recovery (for example, if Berkeley DB is unable 50to allocate heap memory). In such cases, the Berkeley DB methods will 51return <a href="/ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>. 52It is often easier to simply exit the application when such errors occur 53rather than gracefully return up the stack. 54<p>When <b>event</b> is set to DB_EVENT_PANIC, the database 55environment has failed. All threads of control in the database 56environment should exit the environment, and recovery should be run.</p></ul> 57<b><a name="DB_EVENT_REP_CLIENT">DB_EVENT_REP_CLIENT</a></b><ul compact><li>The local site is now a replication client.</ul> 58<b><a name="DB_EVENT_REP_ELECTED">DB_EVENT_REP_ELECTED</a></b><ul compact><li>The local replication site has just won an election. An application using 59the Base replication API should arrange for a call to the <a href="/api_c/rep_start.html">DB_ENV->rep_start</a> method 60after receiving this event, to reconfigure the local environment as a 61replication master.</ul> 62<p>Replication Manager applications may safely ignore this event. The 63Replication Manager calls <a href="/api_c/rep_start.html">DB_ENV->rep_start</a> automatically on behalf of 64the application when appropriate (resulting in firing of the 65DB_EVENT_REP_MASTER event).</p> 66<b><a name="DB_EVENT_REP_MASTER">DB_EVENT_REP_MASTER</a></b><ul compact><li>The local site is now the master site of its replication group. It is 67the application's responsibility to begin acting as the master environment.</ul> 68<b><a name="DB_EVENT_REP_NEWMASTER">DB_EVENT_REP_NEWMASTER</a></b><ul compact><li>The replication group of which this site is a member has just established a 69new master; the local site is not the new master. The 70<b>event_info</b> parameter points to an integer containing the 71environment ID of the new master.</ul> 72<b><a name="DB_EVENT_REP_PERM_FAILED">DB_EVENT_REP_PERM_FAILED</a></b><ul compact><li>The replication manager did not receive enough acknowledgements (based on 73the acknowledgement policy configured with <a href="/api_c/repmgr_ack_policy.html">DB_ENV->repmgr_set_ack_policy</a>) 74to ensure a transaction's durability within the replication group. The 75transaction will be flushed to the master's local disk storage for 76durability.</ul> 77<p>The DB_EVENT_REP_PERM_FAILED event is provided only to applications 78configured for the replication manager.</p> 79<b><a name="DB_EVENT_REP_STARTUPDONE">DB_EVENT_REP_STARTUPDONE</a></b><ul compact><li>The client has completed startup synchronization and is now processing 80live log records received from the master.</ul> 81<b><a name="DB_EVENT_WRITE_FAILED">DB_EVENT_WRITE_FAILED</a></b><ul compact><li>A Berkeley DB write to stable storage failed.</ul> 82<br> 83<b>event_info</b><ul compact><li>The <b>event_info</b> parameter may reference memory which contains 84additional information describing an event. By default, 85<b>event_info</b> is NULL; specific events may pass non-NULL values, 86in which case the event will also describe the memory's structure.</ul> 87<br></ul> 88<br> 89<p>Berkeley DB is not re-entrant. Callback functions should not attempt to make 90library calls (for example, to release locks or close open handles). 91Re-entering Berkeley DB is not guaranteed to work correctly, and the results 92are undefined.</p> 93<hr size=1 noshade> 94<br><b>Class</b> 95<a href="/api_c/env_class.html">DB_ENV</a> 96<br><b>See Also</b> 97<a href="/api_c/env_list.html">Database Environments and Related Methods</a> 98</tt> 99<table width="100%"><tr><td><br></td><td align=right> 100<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> 101</td></tr></table> 102<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 103</body> 104</html> 105
