broker-core/src/main/java/org/apache/qpid/server/queue/RingOverflowPolicyHandler.java

/*
 *  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.
 */

package org.apache.qpid.server.queue;

import org.apache.qpid.server.logging.EventLogger;
import org.apache.qpid.server.logging.messages.QueueMessages;
import org.apache.qpid.server.model.OverflowPolicy;
import org.apache.qpid.server.model.Queue;

public class RingOverflowPolicyHandler implements OverflowPolicyHandler
{
    private final Handler _handler;

    RingOverflowPolicyHandler(final Queue<?> queue,
                              final EventLogger eventLogger)
    {
        _handler = new Handler(queue, eventLogger);
        queue.addChangeListener(_handler);
    }

    @Override
    public void checkOverflow(final QueueEntry newlyEnqueued)
    {
        _handler.checkOverflow();
    }

    private static class Handler extends OverflowPolicyMaximumQueueDepthChangeListener
    {
        private final Queue<?> _queue;
        private final EventLogger _eventLogger;

        public Handler(final Queue<?> queue, final EventLogger eventLogger)
        {
            super(OverflowPolicy.RING);
            _queue = queue;
            _eventLogger = eventLogger;
        }

        @Override
        void onMaximumQueueDepthChange(final Queue<?> queue)
        {
            checkOverflow();
        }

        private void checkOverflow()
        {
            final long maximumQueueDepthMessages = _queue.getMaximumQueueDepthMessages();
            final long maximumQueueDepthBytes = _queue.getMaximumQueueDepthBytes();

            boolean bytesOverflow, messagesOverflow, overflow = false;
            int counter = 0;
            int queueDepthMessages;
            long queueDepthBytes;
            do
            {
                queueDepthMessages = _queue.getQueueDepthMessages();
                queueDepthBytes = _queue.getQueueDepthBytes();

                messagesOverflow = maximumQueueDepthMessages >= 0 && queueDepthMessages > maximumQueueDepthMessages;
                bytesOverflow = maximumQueueDepthBytes >= 0 && queueDepthBytes > maximumQueueDepthBytes;

                if (bytesOverflow || messagesOverflow)
                {
                    if (!overflow)
                    {
                        overflow = true;
                    }

                    QueueEntry entry = _queue.getLeastSignificantOldestEntry();

                    if (entry != null)
                    {
                        counter++;
                        _queue.deleteEntry(entry);
                    }
                    else
                    {
                        queueDepthMessages = _queue.getQueueDepthMessages();
                        queueDepthBytes = _queue.getQueueDepthBytes();
                        break;
                    }
                }
            }
            while (bytesOverflow || messagesOverflow);

            if (overflow)
            {
                _eventLogger.message(_queue.getLogSubject(), QueueMessages.DROPPED(counter,
                                                                                   queueDepthBytes,
                                                                                   queueDepthMessages,
                                                                                   maximumQueueDepthBytes,
                                                                                   maximumQueueDepthMessages));
            }
        }
    }

}