| /* |
| * 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.openjpa.util; |
| |
| import java.util.Collection; |
| |
| /** |
| * Interface for components that track changes to containers at a |
| * fine-grained level. Proxies that use change trackers might have better |
| * update performance than non-tracking proxies. |
| * |
| * @author Abe White |
| */ |
| public interface ChangeTracker { |
| |
| /** |
| * Return true if this tracker has an up-to-date view of all the changes |
| * to the container it is managing. |
| */ |
| boolean isTracking(); |
| |
| /** |
| * Reset the state of the change tracker, and turn change tracking back |
| * on if it has been disabled. |
| */ |
| void startTracking(); |
| |
| /** |
| * Tell the tracker to stop tracking changes for its container. |
| */ |
| void stopTracking(); |
| |
| /** |
| * Return the collection of values that need to be added to the managed |
| * container. |
| */ |
| Collection getAdded(); |
| |
| /** |
| * Return the set of values that need to be removed from the managed |
| * container. |
| */ |
| Collection getRemoved(); |
| |
| /** |
| * Return the set of elements that have changed. In maps, this marks a |
| * possible change in value for a key. In collections, this marks an |
| * element that has been removed and re-added. |
| */ |
| Collection getChanged(); |
| |
| /** |
| * The next element sequence value for this proxy at load time. |
| * If the data store keeps this proxy's data in sequence order but allows |
| * holes for removed objects, the implementation can set the next |
| * sequence at load time, then retrieve it and start from there for |
| * added objects at flush time. This value is set back to 0 if the |
| * proxy stops tracking changes. For ordered proxies, it is set to the |
| * proxy's size when the proxy starts tracking changes again. |
| */ |
| int getNextSequence(); |
| |
| /** |
| * The maximum element sequence value for this proxy at load time. |
| * If the data store keeps this proxy's data in sequence order but allows |
| * holes for removed objects, the implementation can set the next |
| * sequence at load time, then retrieve it and start from there for |
| * added objects at flush time. This value is set back to 0 if the |
| * proxy stops tracking changes. For ordered proxies, it is set to the |
| * proxy's size when the proxy starts tracking changes again. |
| */ |
| void setNextSequence (int seq); |
| } |