<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>DB_ENV->set_event_notify()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> <link rel="up" href="env.html" title="Chapter 5. The DB_ENV Handle" /> <link rel="prev" href="envset_encrypt.html" title="DB_ENV->set_encrypt()" /> <link rel="next" href="envset_errcall.html" title="DB_ENV->set_errcall()" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DB_ENV->set_event_notify()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="envset_encrypt.html">Prev</a> </td> <th width="60%" align="center">Chapter 5. The DB_ENV Handle </th> <td width="20%" align="right"> <a accesskey="n" href="envset_errcall.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="envevent_notify"></a>DB_ENV->set_event_notify()</h2> </div> </div> </div> <pre class="programlisting">#include <db.h> int DB_ENV->set_event_notify(DB_ENV *dbenv, void (*db_event_fcn)(DB_ENV *dbenv, u_int32_t event, void *event_info)); </pre> <p> The <code class="methodname">DB_ENV->set_event_notify()</code> method configures a callback function which is called to notify the process of specific Berkeley DB events. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> Berkeley DB is not re-entrant. Callback functions should not attempt to make library calls (for example, to release locks or close open handles). Re-entering Berkeley DB is not guaranteed to work correctly, and the results are undefined. </p> </div> <p> The <code class="methodname">DB_ENV->set_event_notify()</code> method configures operations performed using the specified <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle, not all operations performed on the underlying database environment. </p> <p> The <code class="methodname">DB_ENV->set_event_notify()</code> method may be called at any time during the life of the application. </p> <p> The <code class="methodname">DB_ENV->set_event_notify()</code> <span> <span> method returns a non-zero error value on failure and 0 on success. </span> </span> </p> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1667925"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1667873"></a>db_event_fcn</h4> </div> </div> </div> <p> The <span class="bold"><strong>db_event_fcn</strong></span> parameter is the application's event notification function. The function takes three parameters: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <code class="literal">dbenv</code> </p> <p> The <span class="bold"><strong>dbenv</strong></span> parameter is the enclosing database environment handle. </p> </li> <li> <p> <code class="literal">event</code> </p> <p> The <span class="bold"><strong>event</strong></span> parameter is one of the following values: </p> <div class="itemizedlist"> <ul type="circle"> <li> <p><a id="event_notify_DB_EVENT_PANIC"></a> <code class="literal">DB_EVENT_PANIC</code> </p> <p> Errors can occur in the Berkeley DB library where the only solution is to shut down the application and run recovery (for example, if Berkeley DB is unable to allocate heap memory). In such cases, the Berkeley DB methods will return <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_RUNRECOVERY" class="olink">DB_RUNRECOVERY</a>. It is often easier to simply exit the application when such errors occur rather than gracefully return up the stack. </p> <p> When <span class="bold"><strong>event</strong></span> is set to DB_EVENT_PANIC, the database environment has failed. All threads of control in the database environment should exit the environment, and recovery should be run. </p> </li> <li> <p><a id="event_notify_DB_EVENT_REG_ALIVE"></a> <code class="literal">DB_EVENT_REG_ALIVE</code> </p> <p> Recovery is needed in an environment where the <a class="link" href="envopen.html#envopen_DB_REGISTER">DB_REGISTER</a> flag was specified on the <a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method and there is a process attached to the environment. The callback function is triggered once for each process attached. </p> <p> The <span class="bold"><strong>event_info</strong></span> parameter points to a pid_t value containing the process identifier (pid) of the process the Berkeley DB library detects is attached to the environment. </p> </li> <li> <p><a id="event_notify_DB_EVENT_REG_PANIC"></a> <code class="literal">DB_EVENT_REG_PANIC</code> </p> <p> Recovery is needed in an environment where the <a class="link" href="envopen.html#envopen_DB_REGISTER">DB_REGISTER</a> flag was specified on the <a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method. All threads of control in the database environment should exit the environment. </p> <p> This event is different than the <code class="literal">DB_EVENT_PANIC</code> event because it can only be triggered when <code class="literal">DB_REGISTER</code> was specified. It can be used to distinguish between the case when a process dies in the environment and recovery is initiated versus the case when an error happened (for example, if Berkeley DB is unable to allocate heap memory) </p> </li> <li> <p><a id="event_notify_DB_EVENT_REP_CLIENT"></a> <code class="literal">DB_EVENT_REP_CLIENT</code> </p> <p> The local site is now a replication client. </p> </li> <li> <p><a id="event_notify_DB_EVENT_REP_ELECTED"></a> <code class="literal">DB_EVENT_REP_ELECTED</code> </p> <p> The local replication site has just won an election. An application using the Base replication API should arrange for a call to the <a class="xref" href="repstart.html" title="DB_ENV->rep_start()">DB_ENV->rep_start()</a> method after receiving this event, to reconfigure the local environment as a replication master. </p> <p> Replication Manager applications may safely ignore this event. The Replication Manager calls <a class="xref" href="repstart.html" title="DB_ENV->rep_start()">DB_ENV->rep_start()</a> automatically on behalf of the application when appropriate (resulting in firing of the DB_EVENT_REP_MASTER event). </p> </li> <li> <p><a id="event_notify_DB_EVENT_REP_MASTER"></a> <code class="literal">DB_EVENT_REP_MASTER</code> </p> <p> The local site is now the master site of its replication group. It is the application's responsibility to begin acting as the master environment. </p> </li> <li> <p><a id="event_notify_DB_EVENT_REP_NEWMASTER"></a> <code class="literal">DB_EVENT_REP_NEWMASTER</code> </p> <p> The replication group of which this site is a member has just established a new master; the local site is not the new master. The <span class="bold"><strong>event_info</strong></span> parameter points to an integer containing the environment ID of the new master. </p> </li> <li> <p><a id="event_notify_DB_EVENT_REP_PERM_FAILED"></a> <code class="literal">DB_EVENT_REP_PERM_FAILED</code> </p> <p> The replication manager did not receive enough acknowledgements (based on the acknowledgement policy configured with <a class="xref" href="repmgrset_ack_policy.html" title="DB_ENV->repmgr_set_ack_policy()">DB_ENV->repmgr_set_ack_policy()</a> ) to ensure a transaction's durability within the replication group. The transaction will be flushed to the master's local disk storage for durability. </p> <p> The DB_EVENT_REP_PERM_FAILED event is provided only to applications configured for the replication manager. </p> </li> <li> <p><a id="event_notify_DB_EVENT_REP_STARTUPDONE"></a> <code class="literal">DB_EVENT_REP_STARTUPDONE</code> </p> <p> The client has completed startup synchronization and is now processing live log records received from the master. </p> </li> <li> <p><a id="event_notify_DB_EVENT_WRITE_FAILED"></a> <code class="literal">DB_EVENT_WRITE_FAILED</code> </p> <p> A Berkeley DB write to stable storage failed. </p> </li> </ul> </div> </li> <li> <p> <code class="literal">event_info</code> </p> <p> The <span class="bold"><strong>event_info</strong></span> parameter may reference memory which contains additional information describing an event. By default, <span class="bold"><strong>event_info</strong></span> is NULL; specific events may pass non-NULL values, in which case the event will also describe the memory's structure. </p> </li> </ul> </div> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1668209"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1668229"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="envset_encrypt.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="env.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="envset_errcall.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DB_ENV->set_encrypt() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DB_ENV->set_errcall()</td> </tr> </table> </div> </body> </html>