trunk/activemq-core/src/main/java/org/apache/activemq/broker/TransportStatusDetector.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.activemq.broker;

import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.activemq.Service;
import org.apache.activemq.ThreadPriorities;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Used to provide information on the status of the Connection
 * 
 * 
 */
public class TransportStatusDetector implements Service, Runnable {
    private static final Logger LOG = LoggerFactory.getLogger(TransportStatusDetector.class);
    private TransportConnector connector;
    private Set<TransportConnection> collectionCandidates = new CopyOnWriteArraySet<TransportConnection>();
    private AtomicBoolean started = new AtomicBoolean(false);
    private Thread runner;
    private int sweepInterval = 5000;

    TransportStatusDetector(TransportConnector connector) {
        this.connector = connector;
    }

    /**
     * @return Returns the sweepInterval.
     */
    public int getSweepInterval() {
        return sweepInterval;
    }

    /**
     * The sweepInterval to set.
     * 
     * @param sweepInterval
     */
    public void setSweepInterval(int sweepInterval) {
        this.sweepInterval = sweepInterval;
    }

    protected void doCollection() {
        for (Iterator<TransportConnection> i = collectionCandidates.iterator(); i.hasNext();) {
            TransportConnection tc = i.next();
            if (tc.isMarkedCandidate()) {
                if (tc.isBlockedCandidate()) {
                    collectionCandidates.remove(tc);
                    doCollection(tc);
                } else {
                    tc.doMark();
                }
            } else {
                collectionCandidates.remove(tc);
            }
        }
    }

    protected void doSweep() {
        for (Iterator i = connector.getConnections().iterator(); i.hasNext();) {
            TransportConnection connection = (TransportConnection)i.next();
            if (connection.isMarkedCandidate()) {
                connection.doMark();
                collectionCandidates.add(connection);
            }
        }
    }

    protected void doCollection(TransportConnection tc) {
        LOG.warn("found a blocked client - stopping: " + tc);
        try {
            tc.stop();
        } catch (Exception e) {
            LOG.error("Error stopping " + tc, e);
        }
    }

    public void run() {
        while (started.get()) {
            try {
                doCollection();
                doSweep();
                Thread.sleep(sweepInterval);
            } catch (Throwable e) {
                LOG.error("failed to complete a sweep for blocked clients", e);
            }
        }
    }

    public void start() throws Exception {
        if (started.compareAndSet(false, true)) {
            runner = new Thread(this, "ActiveMQ Transport Status Monitor: " + connector);
            runner.setDaemon(true);
            runner.setPriority(ThreadPriorities.BROKER_MANAGEMENT);
            runner.start();
        }
    }

    public void stop() throws Exception {
        started.set(false);
        if (runner != null) {
            runner.join(getSweepInterval() * 5);
        }
    }
}