public class

ShutdownNotifierComponent

extends Object
implements ShutdownNotifier 
//  The contents of this file are subject to the Mozilla Public License
//  Version 1.1 (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.mozilla.org/MPL/
//
//  Software distributed under the License is distributed on an "AS IS"
//  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
//  the License for the specific language governing rights and
//  limitations under the License.
//
//  The Original Code is RabbitMQ.
//
//  The Initial Developer of the Original Code is VMware, Inc.
//  Copyright (c) 2007-2011 VMware, Inc.  All rights reserved.
//


package com.rabbitmq.client.impl;

import java.util.ArrayList;
import java.util.List;

import com.rabbitmq.client.ShutdownListener;
import com.rabbitmq.client.ShutdownNotifier;
import com.rabbitmq.client.ShutdownSignalException;

public class ShutdownNotifierComponent implements ShutdownNotifier {

    /** Monitor for shutdown listeners and shutdownCause */
    private final Object monitor = new Object();

    /** List of all shutdown listeners associated with the component */
    private final List<ShutdownListener> shutdownListeners = new ArrayList<ShutdownListener>();

    /**
     * When this value is null, the component is in an "open"
     * state. When non-null, the component is in "closed" state, and
     * this value indicates the circumstances of the shutdown.
     */
    private volatile ShutdownSignalException shutdownCause = null;

    public void addShutdownListener(ShutdownListener listener)
    {
        ShutdownSignalException sse = null;
        synchronized(this.monitor) {
            sse = this.shutdownCause;
            this.shutdownListeners.add(listener);
        }
        if (sse != null) // closed
            listener.shutdownCompleted(sse);
    }

    public ShutdownSignalException getCloseReason() {
        synchronized(this.monitor) {
            return this.shutdownCause;
        }
    }

    public void notifyListeners()
    {
        ShutdownSignalException sse = null;
        ShutdownListener[] sdls = null;
        synchronized(this.monitor) {
            sdls = this.shutdownListeners
                .toArray(new ShutdownListener[this.shutdownListeners.size()]);
            sse = this.shutdownCause;
        }
        for (ShutdownListener l: sdls) {
            try {
                l.shutdownCompleted(sse);
            } catch (Exception e) {
            // FIXME: proper logging
            }
        }
    }

    public void removeShutdownListener(ShutdownListener listener)
    {
        synchronized(this.monitor) {
            this.shutdownListeners.remove(listener);
        }
    }

    public boolean isOpen() {
        synchronized(this.monitor) {
            return this.shutdownCause == null;
        }
    }

    public boolean setShutdownCauseIfOpen(ShutdownSignalException sse) {
        synchronized (this.monitor) {
            if (isOpen()) {
                this.shutdownCause = sse;
                return true;
            }
            return false;
        }
    }
}