org.alfresco.extension.bulkimport.impl.BulkImportThreadPoolExecutor.java Source code

Java tutorial

Introduction

Here is the source code for org.alfresco.extension.bulkimport.impl.BulkImportThreadPoolExecutor.java

Source

/*
 * Copyright (C) 2007-2016 Peter Monks.
 *               2012      Alain Sahli - Fix for issue 109: http://code.google.com/p/alfresco-bulk-filesystem-import/issues/detail?id=109.
 *
 * 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.
 * 
 * This file is part of an unsupported extension to Alfresco.
 * 
 */

package org.alfresco.extension.bulkimport.impl;

import java.util.concurrent.*;

import org.alfresco.extension.bulkimport.util.ThreadPauser;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import static org.alfresco.extension.bulkimport.util.LogUtils.*;

/**
 * This class provides a simplified <code>ThreadPoolExecutor</code>
 * that uses sensible defaults for the bulk import tool.  Note that calls to
 * <code>execute</code> and <code>submit</code> can block.
 *
 * @author Peter Monks (pmonks@gmail.com)
 */
public class BulkImportThreadPoolExecutor extends ThreadPoolExecutor {
    private final static Log log = LogFactory.getLog(BulkImportThreadPoolExecutor.class);

    private final static int DEFAULT_THREAD_POOL_SIZE = Runtime.getRuntime().availableProcessors() * 4;
    private final static long DEFAULT_KEEP_ALIVE_TIME = 10L;
    private final static TimeUnit DEFAULT_KEEP_ALIVE_TIME_UNIT = TimeUnit.MINUTES;
    private final static int DEFAULT_QUEUE_CAPACITY = 100; // Batches

    private final int queueCapacity;
    private final ThreadPauser pauser;
    private final Semaphore queueSemaphore;

    public BulkImportThreadPoolExecutor(final ThreadPauser pauser, final int threadPoolSize,
            final int queueCapacity, final long keepAliveTime, final TimeUnit keepAliveTimeUnit) {
        super(threadPoolSize <= 0 ? DEFAULT_THREAD_POOL_SIZE : threadPoolSize, // Core pool size
                threadPoolSize <= 0 ? DEFAULT_THREAD_POOL_SIZE : threadPoolSize, // Max pool size (same as core pool size)
                keepAliveTime <= 0 ? DEFAULT_KEEP_ALIVE_TIME : keepAliveTime, // Keep alive
                keepAliveTimeUnit == null ? DEFAULT_KEEP_ALIVE_TIME_UNIT : keepAliveTimeUnit, // Keep alive units
                new LinkedBlockingQueue<Runnable>(), // Queue of maximum size
                new BulkImportThreadFactory(), // Thread factory
                new ThreadPoolExecutor.AbortPolicy()); // Rejection handler (shouldn't ever be called, due to the use of a semaphone before task submission)

        this.queueCapacity = queueCapacity;
        this.pauser = pauser;

        final int queuePlusPoolSize = (queueCapacity <= 0 ? DEFAULT_QUEUE_CAPACITY : queueCapacity)
                + (threadPoolSize <= 0 ? DEFAULT_THREAD_POOL_SIZE : threadPoolSize);
        this.queueSemaphore = new Semaphore(queuePlusPoolSize);

        if (debug(log))
            debug(log, "Created new bulk import thread pool." + " Thread Pool Size="
                    + (threadPoolSize <= 0 ? DEFAULT_THREAD_POOL_SIZE : threadPoolSize) + ", Queue Capacity="
                    + ((queueCapacity <= 0 ? DEFAULT_QUEUE_CAPACITY : queueCapacity) + 2) + ", Keep Alive Time="
                    + (keepAliveTime <= 0 ? DEFAULT_KEEP_ALIVE_TIME : keepAliveTime) + " "
                    + String.valueOf(keepAliveTimeUnit == null ? DEFAULT_KEEP_ALIVE_TIME_UNIT : keepAliveTimeUnit));
    }

    /**
     * @see {@link ThreadPoolExecutor#beforeExecute(Thread, Runnable)}
     */
    @Override
    protected void beforeExecute(final Thread thread, final Runnable runnable) {
        super.beforeExecute(thread, runnable);

        try {
            pauser.blockIfPaused();
        } catch (final InterruptedException ie) // Curse you checked exceptions!!!!
        {
            Thread.currentThread().interrupt();
            throw new RuntimeException(ie);
        }
    }

    /**
     * @see {@link ThreadPoolExecutor#execute(Runnable)}
     */
    @Override
    public void execute(final Runnable command) {
        try {
            if (debug(log) && queueSemaphore.availablePermits() <= 0)
                debug(log, "Worker threads are saturated, scanning will block.");

            queueSemaphore.acquire();
        } catch (final InterruptedException ie) {
            Thread.currentThread().interrupt();
            throw new RuntimeException(ie); // Checked exceptions are the bane of my existence...
        }

        try {
            if (super.isTerminating() || super.isShutdown() || super.isTerminated()) {
                if (debug(log))
                    debug(log, "New work submitted during shutdown - ignoring new work.");
            } else {
                super.execute(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            command.run();
                        } finally {
                            // Note: queueSemaphore must be released by the worker thread, not the scanner thread!
                            queueSemaphore.release();
                        }
                    }
                });
            }
        } catch (final RejectedExecutionException ree) {
            // If this triggers, it's a bug in the back-pressure logic
            queueSemaphore.release();
            throw new IllegalStateException("Worker threads were saturated (available permits = "
                    + String.valueOf(queueSemaphore.availablePermits()) + "), "
                    + "but scanning didn't block, resulting in a RejectedExecutionException. "
                    + "This is probably a bug in the bulk import tool - please raise an issue at https://github.com/pmonks/alfresco-bulk-import/issues/, including this full stack trace (and all \"caused by\" stack traces).",
                    ree);
        }
    }

    /**
     * @return The current size (number of items) on the queue.
     */
    public int getQueueSize() {
        return (getQueue().size());
    }

    /**
     * @return The maximum possible capacity of the queue.
     */
    public int getQueueCapacity() {
        return (queueCapacity);
    }

    /**
     * @return Is the work queue for this thread pool empty?
     */
    public boolean isQueueEmpty() {
        return (getQueue().isEmpty());
    }

}