com.sleepycat.je.txn.UndoReader Maven / Gradle / Ivy
/*-
* Copyright (C) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
*
* This file was distributed by Oracle as part of a version of Oracle Berkeley
* DB Java Edition made available at:
*
* http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
*
* Please see the LICENSE file included in the top-level directory of the
* appropriate version of Oracle Berkeley DB Java Edition for a copy of the
* license and additional information.
*/
package com.sleepycat.je.txn;
import java.util.Map;
import com.sleepycat.je.EnvironmentFailureException;
import com.sleepycat.je.dbi.DatabaseId;
import com.sleepycat.je.dbi.DatabaseImpl;
import com.sleepycat.je.dbi.DbTree;
import com.sleepycat.je.dbi.EnvironmentImpl;
import com.sleepycat.je.log.LNFileReader;
import com.sleepycat.je.log.WholeEntry;
import com.sleepycat.je.log.entry.LNLogEntry;
import com.sleepycat.je.tree.LN;
import com.sleepycat.je.utilint.DbLsn;
/**
* Convenience class to package together the different steps and fields needed
* for reading a log entry for undoing. Is used for both txn aborts and
* recovery undos.
*/
public class UndoReader {
public final LNLogEntry logEntry;
public final LN ln;
private final long lsn;
public final int logEntrySize;
public final DatabaseImpl db;
private UndoReader(LNLogEntry logEntry,
LN ln,
long lsn,
int logEntrySize,
DatabaseImpl db) {
this.logEntry = logEntry;
this.ln = ln;
this.lsn = lsn;
this.logEntrySize = logEntrySize;
this.db = db;
}
/**
* Set up an UndoReader when doing an undo or txn partial rollback for a
* live txn.
*
* Never returns null. The DB ID of the LN must be present in
* undoDatabases, or a fatal exception is thrown.
*/
public static UndoReader create(
EnvironmentImpl envImpl,
long undoLsn,
Map undoDatabases) {
final WholeEntry wholeEntry = envImpl.getLogManager().
getWholeLogEntryHandleNotFound(undoLsn);
final int logEntrySize = wholeEntry.getHeader().getEntrySize();
final LNLogEntry logEntry = (LNLogEntry) wholeEntry.getEntry();
final DatabaseId dbId = logEntry.getDbId();
final DatabaseImpl db = undoDatabases.get(dbId);
if (db == null) {
throw EnvironmentFailureException.unexpectedState
(envImpl,
"DB not found during non-recovery undo/rollback, id=" + dbId);
}
logEntry.postFetchInit(db);
final LN ln = logEntry.getLN();
final long lsn = undoLsn;
ln.postFetchInit(db, undoLsn);
return new UndoReader(logEntry, ln, lsn, logEntrySize, db);
}
/**
* Set up an UndoReader when doing a recovery partial rollback. In that
* case, we have a file reader positioned at the pertinent log entry.
*
* This method calls DbTree.getDb. The caller is responsible for calling
* DbTree.releaseDb on the db field.
*
* Null is returned if the DB ID of the LN has been deleted.
*/
public static UndoReader createForRecovery(LNFileReader reader,
DbTree dbMapTree) {
final LNLogEntry logEntry = reader.getLNLogEntry();
final DatabaseId dbId = logEntry.getDbId();
final DatabaseImpl db = dbMapTree.getDb(dbId);
if (db == null) {
return null;
}
logEntry.postFetchInit(db);
final LN ln = logEntry.getLN();
final long lsn = reader.getLastLsn();
ln.postFetchInit(db, lsn);
final int logEntrySize = reader.getLastEntrySize();
return new UndoReader(logEntry, ln, lsn, logEntrySize, db);
}
@Override
public String toString() {
return ln + " lsn=" + DbLsn.getNoFormatString(lsn);
}
}