001// Copyright 2008-2013 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5;
016
017import java.io.IOException;
018import java.io.Serializable;
019import java.util.concurrent.atomic.AtomicBoolean;
020
021/**
022 * Base implementation of
023 * {@link org.apache.tapestry5.OptimizedSessionPersistedObject}. Subclasses
024 * should invoke {@link #markDirty()} after the internal state of the object changes.
025 * <p>
026 * Due to the concurrent nature of session attributes it's important that markDirty occurs <strong>after</strong>
027 * the object has been changed. If the change occurs before the object has been mutated it's possible that another
028 * thread may re-store the object before the changes are actually made!
029 * <p>
030 * @since 5.1.1.0
031 */
032public abstract class BaseOptimizedSessionPersistedObject implements OptimizedSessionPersistedObject, Serializable
033{
034    private static final long serialVersionUID = 172352928643322125L;
035
036    private transient AtomicBoolean dirty = new AtomicBoolean(false);
037
038    private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
039        dirty = new AtomicBoolean(false);
040    }
041
042    public final boolean checkAndResetDirtyMarker()
043    {
044        return dirty.getAndSet(false);
045    }
046
047    /**
048     * Invoked by the subclass after internal state of the object changes.
049     */
050    protected final void markDirty()
051    {
052        dirty.set(true);
053    }
054}