/*
 *
 * Copyright (c) 2006 The Apache Software Foundation
 *
 * 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.apache.qpid.server.cluster;

import org.apache.mina.common.IoSession;

import java.util.LinkedList;
import java.util.Queue;

/**
 * Buffers any received messages until join completes.
 *
 */
class InductionBuffer
{
    private final Queue<Message> _buffer = new LinkedList<Message>();
    private final MessageHandler _handler;
    private boolean _buffering = true;

    InductionBuffer(MessageHandler handler)
    {
        _handler = handler;
    }

    private void process() throws Exception
    {
        for (Message o = _buffer.poll(); o != null; o = _buffer.poll())
        {
            o.deliver(_handler);
        }
        _buffering = false;
    }

    synchronized void deliver() throws Exception
    {
        process();
    }

    synchronized void receive(IoSession session, Object msg) throws Exception
    {
        if (_buffering)
        {
            _buffer.offer(new Message(session, msg));
        }
        else
        {
            _handler.deliver(session, msg);
        }
    }

    private static class Message
    {
        private final IoSession _session;
        private final Object _msg;

        Message(IoSession session, Object msg)
        {
            _session = session;
            _msg = msg;
        }

        void deliver(MessageHandler handler) throws Exception
        {
            handler.deliver(_session, _msg);
        }
    }

    static interface MessageHandler
    {
        public void deliver(IoSession session, Object msg) throws Exception;
    }
}
