org.apache.jackrabbit.oak.spi.commit.DiffObserver Maven / Gradle / Ivy
/*
* 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.oak.spi.commit;
import static com.google.common.base.Preconditions.checkNotNull;
import javax.annotation.Nonnull;
import org.apache.jackrabbit.oak.spi.state.NodeState;
import org.apache.jackrabbit.oak.spi.state.NodeStateDiff;
/**
* Abstract base class for observers that use a content diff to determine
* what changed between two consecutive observed states of the repository.
* Subclasses just need to provide the diff handler by implementing the
* {@link #getRootDiff(NodeState, NodeState, CommitInfo)} method.
*/
public abstract class DiffObserver implements Observer {
private NodeState before = null;
/**
* Returns the diff handler to be used for the given content change.
*
* @param before state of the repository before this changes
* @param after state of the repository after this changes
* @param info local commit information, or {@code null} if not available
* @return diff handler for this change
*/
protected abstract NodeStateDiff getRootDiff(
@Nonnull NodeState before, @Nonnull NodeState after,
@Nonnull CommitInfo info);
//----------------------------------------------------------< Observer >--
@Override
public final synchronized void contentChanged(
@Nonnull NodeState root, @Nonnull CommitInfo info) {
checkNotNull(root);
if (before != null) {
NodeStateDiff diff = getRootDiff(before, root, info);
root.compareAgainstBaseState(before, diff);
}
before = root;
}
}