RC9/qpid/java/broker/src/main/java/org/apache/qpid/server/flow/MessageAndBytesCreditManager.java

package org.apache.qpid.server.flow;

import org.apache.qpid.server.queue.AMQMessage;

import java.util.concurrent.atomic.AtomicLong;

/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you 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.
*
*/
public class MessageAndBytesCreditManager extends AbstractFlowCreditManager implements FlowCreditManager
{
    private long _messageCredit;
    private long _bytesCredit;

    MessageAndBytesCreditManager(final long messageCredit, final long bytesCredit)
    {
        _messageCredit = messageCredit;
        _bytesCredit = bytesCredit;
    }

    public synchronized void addCredit(long messageCredit, long bytesCredit)
    {
        _messageCredit += messageCredit;
        _bytesCredit += bytesCredit;
        setSuspended(hasCredit());
    }

    public synchronized void removeAllCredit()
    {
        _messageCredit = 0L;
        _bytesCredit = 0L;
        setSuspended(true);
    }

    public synchronized boolean hasCredit()
    {
        return (_messageCredit > 0L) && ( _bytesCredit > 0L );
    }

    public synchronized boolean useCreditForMessage(AMQMessage msg)
    {
        if(_messageCredit == 0L)
        {
            setSuspended(true);
            return false;
        }
        else
        {
            final long msgSize = msg.getSize();
            if(msgSize > _bytesCredit)
            {
                setSuspended(true);
                return false;
            }
            _messageCredit--;
            _bytesCredit -= msgSize;
            setSuspended(false);
            return true;
        }
        
    }
}