/*
 * Copyright (c) 2016 Goldman Sachs.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v. 1.0 which accompany this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */

package org.eclipse.collections.impl.parallel;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;

import org.eclipse.collections.api.block.function.Function;
import org.eclipse.collections.api.block.procedure.Procedure;
import org.eclipse.collections.impl.utility.ArrayIterate;

public final class ArrayProcedureFJTaskRunner<T, BT extends Procedure<? super T>>
{
    private final Function<ArrayProcedureFJTask<T, BT>, BT> procedureFunction = new ProcedureExtractor();
    private ArrayProcedureFJTask<T, BT>[] procedures;
    private Throwable error;
    private final CountDownLatch latch;
    private final Combiner<BT> combiner;
    private final BlockingQueue<BT> outputQueue;
    private final int taskCount;

    public ArrayProcedureFJTaskRunner(Combiner<BT> newCombiner, int newTaskCount)
    {
        this.combiner = newCombiner;
        this.taskCount = newTaskCount;
        if (this.combiner.useCombineOne())
        {
            this.outputQueue = new ArrayBlockingQueue<>(newTaskCount);
            this.latch = null;
        }
        else
        {
            this.latch = new CountDownLatch(newTaskCount);
            this.outputQueue = null;
        }
    }

    
Creates an array of ProcedureFJTasks wrapping Procedures created by the specified ProcedureFactory.
/** * Creates an array of ProcedureFJTasks wrapping Procedures created by the specified ProcedureFactory. */
private void createAndExecuteTasks(Executor executor, ProcedureFactory<BT> procedureFactory, T[] array) { this.procedures = new ArrayProcedureFJTask[this.taskCount]; int sectionSize = array.length / this.taskCount; for (int index = 0; index < this.taskCount; index++) { ArrayProcedureFJTask<T, BT> procedureFJTask = new ArrayProcedureFJTask<>(this, procedureFactory, array, index, sectionSize, index == this.taskCount - 1); this.procedures[index] = procedureFJTask; executor.execute(procedureFJTask); } } public void taskCompleted(ArrayProcedureFJTask<T, BT> task) { if (this.combiner.useCombineOne()) { this.outputQueue.add(task.getProcedure()); } else { this.latch.countDown(); } } private void join() { try { if (this.combiner.useCombineOne()) { int remainingTaskCount = this.taskCount; while (remainingTaskCount > 0) { this.combiner.combineOne(this.outputQueue.take()); remainingTaskCount--; } } else { this.latch.await(); } } catch (InterruptedException e) { throw new RuntimeException("Combine failed", e); } } public void executeAndCombine(Executor executor, ProcedureFactory<BT> procedureFactory, T[] array) { this.createAndExecuteTasks(executor, procedureFactory, array); this.join(); if (this.error != null) { throw new RuntimeException("One or more parallel tasks failed", this.error); } //don't combine until the lock is notified this.combineTasks(); } public void setFailed(Throwable newError) { this.error = newError; } private void combineTasks() { if (!this.combiner.useCombineOne()) { this.combiner.combineAll(ArrayIterate.collect(this.procedures, this.procedureFunction)); } } private final class ProcedureExtractor implements Function<ArrayProcedureFJTask<T, BT>, BT> { private static final long serialVersionUID = 1L; @Override public BT valueOf(ArrayProcedureFJTask<T, BT> object) { return object.getProcedure(); } } }