    001// Copyright 2006, 2007, 2008, 2011, 2012 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.internal.event;
    016
    017import org.apache.tapestry5.commons.services.InvalidationEventHub;
    018import org.apache.tapestry5.commons.services.InvalidationListener;
    019import org.apache.tapestry5.commons.util.CollectionFactory;
    020
    021import java.util.List;
    022import java.util.Map;
    023
    024/**
    025 * Base implementation class for classes (especially services) that need to manage a list of
    026 * {@link org.apache.tapestry5.commons.services.InvalidationListener}s.
    027 */
    028public class InvalidationEventHubImpl implements InvalidationEventHub
    029{
    030    private final List<Runnable> callbacks;
    031
    032    protected InvalidationEventHubImpl(boolean productionMode)
    033    {
    034        if (productionMode)
    035        {
    036            callbacks = null;
    037        } else
    038        {
    039            callbacks = CollectionFactory.newThreadSafeList();
    040        }
    041    }
    042
    043    /**
    044     * Notifies all listeners/callbacks.
    045     */
    046    protected final void fireInvalidationEvent()
    047    {
    048        if (callbacks == null)
    049        {
    050            return;
    051        }
    052
    053        for (Runnable callback : callbacks)
    054        {
    055            callback.run();
    056        }
    057    }
    058
    059    public final void addInvalidationCallback(Runnable callback)
    060    {
    061        assert callback != null;
    062
    063        // In production mode, callbacks may be null, in which case, just
    064        // ignore the callback.
    065        if (callbacks != null)
    066        {
    067            callbacks.add(callback);
    068        }
    069    }
    070
    071    public final void clearOnInvalidation(final Map<?, ?> map)
    072    {
    073        assert map != null;
    074
    075        addInvalidationCallback(new Runnable()
    076        {
    077            public void run()
    078            {
    079                map.clear();
    080            }
    081        });
    082    }
    083
    084    public final void addInvalidationListener(final InvalidationListener listener)
    085    {
    086        assert listener != null;
    087
    088        addInvalidationCallback(new Runnable()
    089        {
    090            public void run()
    091            {
    092                listener.objectWasInvalidated();
    093            }
    094        });
    095    }
    096
    097}