env_set_app_dispatch.html [plain text]
<!--$Id: env_set_app_dispatch.html,v 1.1.1.1 2003/02/15 04:55:51 zarzycki Exp $-->
<!--Copyright 1997-2002 by Sleepycat Software, Inc.-->
<!--All rights reserved.-->
<!--See the file LICENSE for redistribution information.-->
<html>
<head>
<title>Berkeley DB: DbEnv.set_app_dispatch</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++">
</head>
<body bgcolor=white>
<a name="2"><!--meow--></a>
<table width="100%"><tr valign=top>
<td>
<h1>DbEnv.set_app_dispatch</h1>
</td>
<td align=right>
<a href="../api_java/c_index.html"><img src="../images/api.gif" alt="API"></a><a href="../reftoc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<hr size=1 noshade>
<tt>
<h3><pre>
import com.sleepycat.db.*;
<p>
public interface DbTxnRecover
{
public abstract int
tx_recover(DbEnv dbenv, Dbt log_rec, DbLsn lsn, int op);
}
public class DbEnv
{
public void set_app_dispatch(DbTxnRecover tx_recover)
throws DbException;
...
}
</pre></h3>
<h1>Description</h1>
<p>Set the application's method to be called during transaction abort
and recovery. This method must return 0 on success and either
<b>errno</b> or a value outside of the Berkeley DB error name space on
failure. It takes four arguments:
<p><dl compact>
<p><dt>dbenv <dd>A Berkeley DB environment.
<p><dt>log_rec<dd>A log record.
<p><dt>lsn<dd>A log sequence number.
<p><dt>op<dd>One of the following values:
<p><dl compact>
<p><dt><a name="Db.DB_TXN_BACKWARD_ROLL">Db.DB_TXN_BACKWARD_ROLL</a><dd>The log is being read backward to determine which transactions have been
committed and to abort those operations that were not; undo the operation
described by the log record.
<p><dt><a name="Db.DB_TXN_FORWARD_ROLL">Db.DB_TXN_FORWARD_ROLL</a><dd>The log is being played forward; redo the operation described by the log
record.
<p><dt><a name="Db.DB_TXN_ABORT">Db.DB_TXN_ABORT</a><dd>The log is being read backward during a transaction abort; undo the
operation described by the log record.
<p><dt><a name="Db.DB_TXN_APPLY">Db.DB_TXN_APPLY</a><dd>The log is being applied on a replica site; redo the operation
described by the log record.
<p><dt><a name="Db.DB_TXN_PRINT">Db.DB_TXN_PRINT</a><dd>The log is being printed for debugging purposes; print the contents of
this log record in the desired format.
</dl>
</dl>
<p>The Db.DB_TXN_FORWARD_ROLL and Db.DB_TXN_APPLY operations
frequently imply the same actions, redoing changes that appear in the
log record, although if a recovery function is to be used on a
replication client where reads may be taking place concurrently with
the processing of incoming messages, Db.DB_TXN_APPLY operations
should also perform appropriate locking. The macro DB_REDO(op) checks
that the operation is one of Db.DB_TXN_FORWARD_ROLL or
Db.DB_TXN_APPLY, and should be used in the recovery code to refer
to the conditions under which operations should be redone. Similarly,
the macro DB_UNDO(op) checks if the operation is one of
Db.DB_TXN_BACKWARD_ROLL or Db.DB_TXN_ABORT.
<p>The DbEnv.set_app_dispatch method configures operations performed using the specified
<a href="../api_java/env_class.html">DbEnv</a> handle, not all operations performed on the underlying
database environment.
<p>The DbEnv.set_app_dispatch interface may not be called after the <a href="../api_java/env_open.html">DbEnv.open</a>
interface is called.
If the database environment already exists when
<a href="../api_java/env_open.html">DbEnv.open</a> is called, the information specified to DbEnv.set_app_dispatch
must be consistent with the existing environment or corruption can
occur.
<p>The DbEnv.set_app_dispatch method throws an exception that encapsulates a non-zero error value on
failure.
<h1>Errors</h1>
<p>The DbEnv.set_app_dispatch method may fail and throw an exception encapsulating a non-zero error for the following conditions:
<p><dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
<p>Called after <a href="../api_java/env_open.html">DbEnv.open</a> was called.
</dl>
<p>The DbEnv.set_app_dispatch method may fail and throw an exception for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the DbEnv.set_app_dispatch method may fail and
throw a <a href="../api_java/runrec_class.html">DbRunRecoveryException</a>,
in which case all subsequent Berkeley DB calls will fail in the same way.
<h1>Class</h1>
<a href="../api_java/env_class.html">DbEnv</a>, <a href="../api_java/txn_class.html">DbTxn</a>
<h1>See Also</h1>
<a href="../api_java/txn_list.html">Transaction Subsystem and Related Methods</a>
</tt>
<table width="100%"><tr><td><br></td><td align=right>
<a href="../api_java/c_index.html"><img src="../images/api.gif" alt="API"></a><a href="../reftoc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font>
</body>
</html>