/*
* Hibernate OGM, Domain model persistence for NoSQL datastores
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later
* See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
*/
package org.hibernate.ogm.massindex.impl;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.hibernate.search.util.logging.impl.Log;
import org.hibernate.search.util.logging.impl.LoggerFactory;
/**
* Helper class to create threads;
* these threads are grouped and named to be identified in a profiler.
*
* @author Sanne Grinovero
*/
public class Executors {
public static final int QUEUE_MAX_LENGTH = 1000;
private static final Log log = LoggerFactory.make();
private static final String THREAD_GROUP_PREFIX = "Hibernate OGM: ";
/**
* Creates a new fixed size ThreadPoolExecutor.
* It's using a blockingqueue of maximum 1000 elements and the rejection
* policy is set to CallerRunsPolicy for the case the queue is full.
* These settings are required to cap the queue, to make sure the
* timeouts are reasonable for most jobs.
*
* @param threads
* the number of threads
* @param groupname
* a label to identify the threadpool; useful for profiling.
* @return the new ExecutorService
*/
public static ThreadPoolExecutor newFixedThreadPool(int threads, String groupname) {
return newFixedThreadPool( threads, groupname, QUEUE_MAX_LENGTH );
}
/**
* Creates a new fixed size ThreadPoolExecutor
*
* @param threads
* the number of threads
* @param groupname
* a label to identify the threadpool; useful for profiling.
* @param queueSize
* the size of the queue to store Runnables when all threads are busy
* @return the new ExecutorService
*/
public static ThreadPoolExecutor newFixedThreadPool(int threads, String groupname, int queueSize) {
return new ThreadPoolExecutor( threads, threads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(
queueSize ), new SearchThreadFactory( groupname ), new BlockPolicy() );
}
/**
* The thread factory, used to customize thread names
*/
private static class SearchThreadFactory implements ThreadFactory {
final ThreadGroup group;
final AtomicInteger threadNumber = new AtomicInteger( 1 );
final String namePrefix;
SearchThreadFactory(String groupname) {
SecurityManager s = System.getSecurityManager();
group = ( s != null ) ? s.getThreadGroup() : Thread.currentThread().getThreadGroup();
namePrefix = THREAD_GROUP_PREFIX + groupname + "-";
}
public Thread newThread(Runnable r) {
Thread t = new Thread( group, r, namePrefix + threadNumber.getAndIncrement(), 0 );
return t;
}
}
/**
* A handler for rejected tasks that will have the caller block until
* space is available.
*/
public static class BlockPolicy implements RejectedExecutionHandler {
/**
* Creates a <tt>BlockPolicy</tt>.
*/
public BlockPolicy() {
}
/**
* Puts the Runnable to the blocking queue, effectively blocking
* the delegating thread until space is available.
* @param r
* the runnable task requested to be executed
* @param e
* the executor attempting to execute this task
*/
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
try {
e.getQueue().put( r );
}
catch ( InterruptedException e1 ) {
log.interruptedWorkError( r );
Thread.currentThread().interrupt();
}
}
}
}