/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jackrabbit.core.query.lucene;
import java.io.IOException;
import java.util.List;
/**
* Defines a redo log for changes that have not been committed to disk. While
* nodes are added to and removed from the volatile index (held in memory) a
* redo log is maintained to keep track of the changes. In case the Jackrabbit
* process terminates unexpected the redo log is applied when Jackrabbit is
* restarted the next time.
*/
public interface RedoLog {
/**
* Returns <code>true</code> if this redo log contains any entries,
* <code>false</code> otherwise.
* @return <code>true</code> if this redo log contains any entries,
* <code>false</code> otherwise.
*/
boolean hasEntries();
/**
* Returns the number of entries in this redo log.
* @return the number of entries in this redo log.
*/
int getSize();
/**
* Returns a List with all {@link MultiIndex.Action} instances in the
* redo log.
*
* @return an List with all {@link MultiIndex.Action} instances in the
* redo log.
* @throws IOException if an error occurs while reading from the redo log.
*/
List<MultiIndex.Action> getActions() throws IOException;
/**
* Appends an action to the log.
*
* @param action the action to append.
* @throws IOException if the node cannot be written to the redo
* log.
*/
void append(MultiIndex.Action action) throws IOException;
/**
* Flushes all pending writes to the redo log.
*
* @throws IOException if an error occurs while writing.
*/
void flush() throws IOException;
/**
* Flushes all pending writes to the redo log and closes it.
*
* @throws IOException if an error occurs while writing.
*/
void close() throws IOException;
}