| /* |
| * 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 org.apache.jackrabbit.oak.spi.state.NodeState; |
| import org.apache.jackrabbit.oak.spi.state.NodeStateDiff; |
| import org.jetbrains.annotations.NotNull; |
| |
| /** |
| * 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( |
| @NotNull NodeState before, @NotNull NodeState after, |
| @NotNull CommitInfo info); |
| |
| //----------------------------------------------------------< Observer >-- |
| |
| @Override |
| public final synchronized void contentChanged( |
| @NotNull NodeState root, @NotNull CommitInfo info) { |
| checkNotNull(root); |
| if (before != null) { |
| NodeStateDiff diff = getRootDiff(before, root, info); |
| root.compareAgainstBaseState(before, diff); |
| } |
| before = root; |
| } |
| |
| } |