    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005//     http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5;
    014
    015import java.io.IOException;
    016import java.io.Serializable;
    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 *
    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 *
    028 * @since 5.1.1.0
    029 */
    030public abstract class BaseOptimizedSessionPersistedObject implements OptimizedSessionPersistedObject, Serializable
    031{
    032    private static final long serialVersionUID = 172352928643322125L;
    033
    034    private transient AtomicBoolean dirty = new AtomicBoolean(false);
    035
    036    private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
    037        dirty = new AtomicBoolean(false);
    038    }
    039
    040    public final boolean checkAndResetDirtyMarker()
    041    {
    042        return dirty.getAndSet(false);
    043    }
    044
    045    /**
    046     * Invoked by the subclass after internal state of the object changes.
    047     */
    048    protected final void markDirty()
    049    {
    050        dirty.set(true);
    051    }
    052}