GAEGravity.java

/**
 *   GRANITE DATA SERVICES
 *   Copyright (C) 2006-2015 GRANITE DATA SERVICES S.A.S.
 *
 *   This file is part of the Granite Data Services Platform.
 *
 *   Granite Data Services is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   Granite Data Services is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
 *   General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 *   USA, or see <http://www.gnu.org/licenses/>.
 */
package org.granite.gravity.gae;

import org.granite.config.GraniteConfig;
import org.granite.config.flex.ServicesConfig;
import org.granite.gravity.Channel;
import org.granite.gravity.ChannelFactory;
import org.granite.gravity.DefaultGravity;
import org.granite.gravity.GravityConfig;
import org.granite.gravity.Subscription;
import org.granite.util.UUIDUtil;

import com.google.appengine.api.memcache.Expiration;
import com.google.appengine.api.memcache.MemcacheService;
import com.google.appengine.api.memcache.MemcacheServiceFactory;

import flex.messaging.messages.Message;

/**
 * @author William DRAI
 * @author Franck WOLFF
 */
public class GAEGravity extends DefaultGravity {

    ///////////////////////////////////////////////////////////////////////////
    // Fields.
    
    static final String CHANNEL_PREFIX = "org.granite.gravity.gae.channel.";
    
    private static MemcacheService gaeCache = MemcacheServiceFactory.getMemcacheService();
    
    ///////////////////////////////////////////////////////////////////////////
    // Constructor.

    public GAEGravity(GravityConfig gravityConfig, ServicesConfig servicesConfig, GraniteConfig graniteConfig) {
    	super(gravityConfig, servicesConfig, graniteConfig);
    }
    

    ///////////////////////////////////////////////////////////////////////////
    // Channel's operations.

    @Override
    protected <C extends Channel> C createChannel(ChannelFactory<C> channelFactory, String channelId) {
    	C channel = null;
    	if (channelId != null) {
    		channel = getChannel(channelFactory, channelId);
    		if (channel != null)
    			return channel;
    	}
    	
    	channel = channelFactory.newChannel(UUIDUtil.randomUUID(), null);
    	Expiration expiration = Expiration.byDeltaMillis((int)getGravityConfig().getChannelIdleTimeoutMillis());
        gaeCache.put(CHANNEL_PREFIX + channel.getId(), channel, expiration);
    	gaeCache.put(GAEChannel.MSG_COUNT_PREFIX + channel.getId(), 0L, expiration);
        return channel;
    }

    @SuppressWarnings("unchecked")
	@Override
    public <C extends Channel> C getChannel(ChannelFactory<C> channelFactory, String channelId) {
        if (channelId == null)
            return null;

        return (C)gaeCache.get(CHANNEL_PREFIX + channelId);
    }


    @Override
    public Channel removeChannel(String channelId, boolean timeout) {
        if (channelId == null)
            return null;

        Channel channel = (Channel)gaeCache.get(CHANNEL_PREFIX + channelId);
        if (channel != null) {
            for (Subscription subscription : channel.getSubscriptions()) {
            	Message message = subscription.getUnsubscribeMessage();
            	handleMessage(channel.getFactory(), message, true);
            }

            channel.destroy(timeout);
            gaeCache.delete(CHANNEL_PREFIX + channelId);
        	gaeCache.delete(GAEChannel.MSG_COUNT_PREFIX + channelId);
        }

        return channel;
    }

    @Override
    public boolean access(String channelId) {
    	return true;
    }
    
    
    @Override
    public void internalStart() {
    	// Avoid starting thread pool
    }

    
    @Override
    protected void postManage(Channel channel) {
    	Expiration expiration = Expiration.byDeltaMillis((int)getGravityConfig().getChannelIdleTimeoutMillis());
    	gaeCache.put(CHANNEL_PREFIX + channel.getId(), channel, expiration);
    }
}