| /* |
| * 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 org.apache.openjpa.lib.util.collections.MapBackedSet; |
| |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.IdentityHashMap; |
| import java.util.Set; |
| |
| /** |
| * Base class that provides utilities to change trackers. |
| * |
| * @author Abe White |
| */ |
| public abstract class AbstractChangeTracker |
| implements ChangeTracker { |
| |
| /** |
| * Collection of added items. May be null. |
| */ |
| protected Collection add = null; |
| |
| /** |
| * Collection of removed items. May be null. |
| */ |
| protected Collection rem = null; |
| |
| /** |
| * Collection of changed items. May be null. |
| */ |
| protected Collection change = null; |
| |
| private boolean _autoOff = true; |
| private boolean _track = false; |
| private Boolean _identity = null; |
| private int _seq = -1; |
| |
| /** |
| * Constructor; supply configuration. |
| */ |
| public AbstractChangeTracker() { |
| } |
| |
| /** |
| * Whether to automatically stop tracking when the number of changes |
| * exceeds the container size. Defaults to true. |
| */ |
| public boolean getAutoOff() { |
| return _autoOff; |
| } |
| |
| /** |
| * Whether to automatically stop tracking when the number of changes |
| * exceeds the container size. Defaults to true. |
| */ |
| public void setAutoOff(boolean autoOff) { |
| _autoOff = autoOff; |
| } |
| |
| @Override |
| public boolean isTracking() { |
| return _track; |
| } |
| |
| @Override |
| public void startTracking() { |
| _track = true; |
| if (_seq == -1) |
| _seq = initialSequence(); |
| reset(); |
| } |
| |
| /** |
| * Return the initial sequence value for this proxy. Typically this is |
| * the container size. Assumes an unordered collection by default, |
| * returning 0. |
| */ |
| protected int initialSequence() { |
| return 0; |
| } |
| |
| @Override |
| public void stopTracking() { |
| _track = false; |
| _seq = -1; |
| reset(); |
| } |
| |
| /** |
| * Reset the state of the tracker. |
| */ |
| protected void reset() { |
| if (add != null) |
| add.clear(); |
| if (rem != null) |
| rem.clear(); |
| if (change != null) |
| change.clear(); |
| _identity = null; |
| } |
| |
| @Override |
| public Collection getAdded() { |
| return (add == null) ? Collections.EMPTY_LIST : add; |
| } |
| |
| @Override |
| public Collection getRemoved() { |
| return (rem == null) ? Collections.EMPTY_LIST : rem; |
| } |
| |
| @Override |
| public Collection getChanged() { |
| return (change == null) ? Collections.EMPTY_LIST : change; |
| } |
| |
| /** |
| * Notify the tracker that the given object was added. |
| */ |
| protected void added(Object val) { |
| if (!_track) |
| return; |
| setIdentity(val); |
| add(val); |
| } |
| |
| /** |
| * Mark the given value as added. |
| */ |
| protected abstract void add(Object val); |
| |
| /** |
| * Notify the tracker that the given object was removed. |
| */ |
| protected void removed(Object val) { |
| if (!_track) |
| return; |
| setIdentity(val); |
| remove(val); |
| } |
| |
| /** |
| * Mark the given value as removed. |
| */ |
| protected abstract void remove(Object val); |
| |
| /** |
| * Notify the tracker that the given object was changed. |
| */ |
| protected void changed(Object val) { |
| if (!_track) |
| return; |
| setIdentity(val); |
| change(val); |
| } |
| |
| /** |
| * Mark the given value as changed. |
| */ |
| protected abstract void change(Object val); |
| |
| @Override |
| public int getNextSequence() { |
| return _seq; |
| } |
| |
| @Override |
| public void setNextSequence(int seq) { |
| _seq = seq; |
| } |
| |
| /** |
| * Create a new set for storing adds/removes/changes. Takes into account |
| * whether we need to use an identity set or standard set. |
| */ |
| protected Set newSet() { |
| if (_identity == Boolean.TRUE) |
| return MapBackedSet.mapBackedSet(new IdentityHashMap()); |
| return new HashSet(); |
| } |
| |
| /** |
| * Set whether to use identity-based datastructures, and switch our current |
| * datastructures appropriately if needed. We use identity structures for |
| * PC types in case the user has coded them such that two objects with |
| * different identities can compare equals(). |
| */ |
| private void setIdentity(Object val) { |
| if (val == null || _identity != null) |
| return; |
| |
| if (ImplHelper.isManagedType(null, val.getClass())) |
| _identity = Boolean.TRUE; |
| else |
| _identity = Boolean.FALSE; |
| |
| add = switchStructure(add, _identity); |
| rem = switchStructure(rem, _identity); |
| change = switchStructure(change, _identity); |
| } |
| |
| /** |
| * Switch from an identity structure to a standard one, or vice versa. |
| */ |
| private static Collection switchStructure(Collection cur, |
| boolean identity) { |
| if (cur == null) |
| return null; |
| if (identity && cur instanceof HashSet) { |
| if (cur.isEmpty()) |
| return null; |
| Set replace = MapBackedSet.mapBackedSet(new IdentityHashMap()); |
| replace.addAll(cur); |
| return replace; |
| } |
| if (!identity && !(cur instanceof HashSet) && cur instanceof Set) { |
| if (cur.isEmpty()) |
| return null; |
| return new HashSet(cur); |
| } |
| return cur; |
| } |
| } |
| |