edu.iu.harp.schdynamic.DynamicScheduler.java Source code

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Here is the source code for edu.iu.harp.schdynamic.DynamicScheduler.java

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/*
 * Copyright 2013-2016 Indiana University
 * 
 * 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 edu.iu.harp.schdynamic;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.Semaphore;

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

public class DynamicScheduler<I, O, T extends Task<I, O>> {

    protected static final Log LOG = LogFactory.getLog(DynamicScheduler.class);

    private final BlockingDeque<Input<I>> inputQueue;
    private final BlockingQueue<Output<O>> outputQueue;

    private Thread[] threads;
    private int inputCount;
    private int outputCount;
    private int errorCount;
    private boolean isRunning;
    private boolean isPausing;
    private final List<TaskMonitor<I, O, T>> taskMonitors;
    private final List<T> tasks;
    private final int numTaskMonitors;
    private final Semaphore barrier1;

    public DynamicScheduler(List<T> tasks) {
        inputQueue = new LinkedBlockingDeque<>();
        outputQueue = new LinkedBlockingQueue<>();
        threads = null;
        inputCount = 0;
        outputCount = 0;
        errorCount = 0;
        isRunning = false;
        isPausing = false;
        barrier1 = new Semaphore(0);
        numTaskMonitors = tasks.size();
        this.tasks = tasks;
        taskMonitors = new ArrayList<>();
        for (T task : tasks) {
            taskMonitors.add(new TaskMonitor<>(inputQueue, outputQueue, task, barrier1));
        }
    }

    public List<T> getTasks() {
        return tasks;
    }

    public synchronized void submit(I input) {
        if (input != null) {
            inputQueue.add(new Input<I>(input, false, false));
            if (isRunning) {
                inputCount++;
            }
        }
    }

    public synchronized void submitAll(Collection<I> inputs) {
        for (I input : inputs) {
            inputQueue.add(new Input<I>(input, false, false));
        }
        if (isRunning) {
            inputCount += inputs.size();
        }
    }

    public synchronized void submitAll(I[] inputs) {
        // Submit inputs
        int submitCount = 0;
        for (I input : inputs) {
            if (input != null) {
                inputQueue.add(new Input<I>(input, false, false));
                submitCount++;
            }
        }
        if (isRunning) {
            inputCount += submitCount;
        }
    }

    public synchronized void start() {
        // Start monitor threads, wait for inputs
        if (!isRunning) {
            isRunning = true;
            inputCount += inputQueue.size();
            if (isPausing) {
                isPausing = false;
                for (TaskMonitor<I, O, T> monitor : taskMonitors) {
                    monitor.release();
                }
            } else {
                threads = new Thread[numTaskMonitors];
                int i = 0;
                for (TaskMonitor<I, O, T> monitor : taskMonitors) {
                    threads[i] = new Thread(monitor);
                    threads[i].start();
                    i++;
                }
            }
        }
    }

    public synchronized void pause() {
        if (isRunning && !isPausing) {
            isRunning = false;
            isPausing = true;
            for (int i = 0; i < numTaskMonitors; i++) {
                inputQueue.addLast(new Input<I>(null, true, false));
            }
            ComputeUtil.acquire(barrier1, numTaskMonitors);
            inputCount -= inputQueue.size();
        }
    }

    public synchronized void pauseNow() {
        if (isRunning && !isPausing) {
            isRunning = false;
            isPausing = true;
            for (int i = 0; i < numTaskMonitors; i++) {
                inputQueue.addFirst(new Input<I>(null, true, false));
            }
            ComputeUtil.acquire(barrier1, numTaskMonitors);
            inputCount -= inputQueue.size();
        }
    }

    public synchronized void cleanInputQueue() {
        if (isPausing || !isRunning) {
            inputQueue.clear();
        }
    }

    public synchronized void stop() {
        // Stop submission
        // Send stop signal to the queue
        // based on the number of tasks
        if (isPausing) {
            start();
        }
        if (isRunning) {
            isRunning = false;
            for (int i = 0; i < numTaskMonitors; i++) {
                inputQueue.addLast(new Input<I>(null, false, true));
            }
            for (int i = 0; i < numTaskMonitors; i++) {
                ComputeUtil.joinThread(threads[i]);
            }
            threads = null;
        }
    }

    /**
     * Invoke as while(hasOutput()) {
     * waitForOutput(); }
     * 
     * @return
     */
    public synchronized O waitForOutput() {
        // If no output is available, wait for one
        if (hasNext()) {
            boolean isFailed = false;
            Output<O> output = null;
            do {
                try {
                    output = outputQueue.take();
                    isFailed = false;
                } catch (Exception e) {
                    output = null;
                    isFailed = true;
                    LOG.error("Error when waiting output", e);
                }
            } while (isFailed);
            outputCount++;
            if (output.isError()) {
                errorCount++;
            }
            return output.getOutput();
        } else {
            return null;
        }
    }

    public synchronized boolean hasOutput() {
        return hasNext();
    }

    private boolean hasNext() {
        return inputCount > outputCount;
    }

    public synchronized boolean hasError() {
        int count = errorCount;
        errorCount = 0;
        return count > 0;
    }
}