FCFSQueue.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 com.chinamobile.bcbsp.bspcontroller;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

class FCFSQueue implements Queue<JobInProgress> {

    private static final Log LOG = LogFactory.getLog(FCFSQueue.class);
    
    private final String name;
    private BlockingQueue<JobInProgress> queue = new LinkedBlockingQueue<JobInProgress>();
    private List<JobInProgress> resort_tmp = new ArrayList<JobInProgress>();

    public FCFSQueue(String name) {
        this.name = name;
    }

    @Override
    public String getName() {
        return this.name;
    }

    @Override
    public void addJob(JobInProgress job) {
        try {
            queue.put(job);
        } catch (InterruptedException ie) {
            LOG.error("Fail to add a job to the " + this.name + " queue.", ie);
        }
    }

    @Override
    public void resortQueue() {
        Comparator<JobInProgress> comp = new Comparator<JobInProgress>() {
            public int compare(JobInProgress o1, JobInProgress o2) {
                int res = o1.getPriority().compareTo(o2.getPriority());
                if (res == 0) {
                    if (o1.getStartTime() < o2.getStartTime())
                        res = -1;
                    else
                        res = (o1.getStartTime() == o2.getStartTime() ? 0 : 1);
                }

                return res;
            }
        };

        synchronized (queue) {
            try {
                resort_tmp.clear();
                int wait_count = queue.size();
                int i = 0;
                for (i = 0; i < wait_count; i++)
                    resort_tmp.add(queue.take());

                Collections.sort(resort_tmp, comp);
                for (i = 0; i < wait_count; i++)
                    queue.put(resort_tmp.get(i));
            } catch (Exception e) {
                LOG.error("resort error: " + e.toString());
            }
        }
    }

    @Override
    public void removeJob(JobInProgress job) {
        queue.remove(job);
    }

    @Override
    public JobInProgress removeJob() {
        try {
            return queue.take();
        } catch (InterruptedException ie) {
            LOG.error("Fail to remove a job from the " + this.name + " queue.",
                    ie);
        } catch (Exception e) {
            // TODO : Here is Exception when stop the JobProcessor Thread.
        }
        return null;
    }

    @Override
    public Collection<JobInProgress> getJobs() {
        return queue;
    }

}