001// Copyright 2008, 2009, 2011 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.util.concurrent.atomic.AtomicBoolean;
018
019/**
020 * Base implementation of
021 * {@link org.apache.tapestry5.OptimizedSessionPersistedObject}. Subclasses
022 * should invoke {@link #markDirty()} after the internal state of the object changes.
023 * <p>
024 * Due to the concurrent nature of session attributes it's important that markDirty occurs <strong>after</strong>
025 * the object has been changed. If the change occurs before the object has been mutated it's possible that another
026 * thread may re-store the object before the changes are actually made!
027 * <p>
028 * @since 5.1.1.0
029 */
030public abstract class BaseOptimizedSessionPersistedObject implements OptimizedSessionPersistedObject
031{
032    private transient AtomicBoolean dirty = new AtomicBoolean(false);
033
034    public final boolean checkAndResetDirtyMarker()
035    {
036        return dirty.getAndSet(false);
037    }
038
039    /**
040     * Invoked by the subclass after internal state of the object changes.
041     */
042    protected final void markDirty()
043    {
044        dirty.set(true);
045    }
046}