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/*
 * Copyright (c) 2009, Paul Merlin. All Rights Reserved.
 * Copyright (c) 2010, Fabien Barbero. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package org.codeartisans.java.sos.messagebus;

import org.codeartisans.java.sos.SOSFailure;
import org.codeartisans.java.sos.threading.WorkQueueComposite;

import org.qi4j.api.injection.scope.Service;
import org.qi4j.api.injection.scope.Structure;
import org.qi4j.api.unitofwork.UnitOfWork;
import org.qi4j.api.unitofwork.UnitOfWorkCompletionException;
import org.qi4j.api.unitofwork.UnitOfWorkFactory;

/**
 * MessageBus Mixin that use a thread to deliver Messages to Subscribers sequentially.
 * The publish method returns immediatly.
 */
public abstract class SingleThreadDeliveryMixin
        extends BaseMessageBus
        implements MessageBusComposite
{

    @Structure
    private UnitOfWorkFactory uowf;
    @Service
    private WorkQueueComposite workQueue;

    @Override
    public  void publish( final Message message )
    {
        workQueue.enqueue( new Runnable()
        {

            @Override
            public void run()
            {
                if ( !vetoed( message ) ) {
                    final UnitOfWork uow = uowf.newUnitOfWork();
                    for ( S eachSubscriber : subscribers( message.getMessageType() ) ) {
                        try {
                            message.deliver( eachSubscriber );
                            uow.complete();
                        } catch ( UnitOfWorkCompletionException ex ) {
                            uow.discard();
                            throw new SOSFailure( "Error during message delivery", ex );
                        }
                    }
                }
            }

        } );
    }

}