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/*
* Copyright (c) 2008-2014 MongoDB, Inc.
*
* 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.
*/
// ThreadPool.java
package com.mongodb.util;
import java.util.List;
import java.util.Vector;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicInteger;
/**
* A thread pool implementation.
*
* @deprecated This class is no longer in use and should not have been public. It may be removed in a future release.
*/
@Deprecated
public abstract class ThreadPool<T> {
/** Initializes a new thread pool with a given name and number of threads.
* @param name identifying name
* @param numThreads the number of threads allowed in the pool
*/
public ThreadPool( String name , int numThreads ){
this( name , numThreads , Integer.MAX_VALUE );
}
/** Initializes a new thread pool with a given name, number of threads, and queue size.
* @param name identifying name
* @param numThreads the number of threads allowed in the pool
* @param maxQueueSize the size of the pool entry queue
*/
public ThreadPool( String name , int numThreads , int maxQueueSize ){
_name = name;
_maxThreads = numThreads;
_queue = new LinkedBlockingQueue<T>( maxQueueSize );
_myThreadGroup = new MyThreadGroup();
_threads.add( new MyThread() );
}
/** Handles a given object.
* @param t the object to handle
* @throws Exception
*/
public abstract void handle( T t )
throws Exception ;
/** Handles a given object and exception.
* @param t the object to handle
* @param e the exception to handle
*/
public abstract void handleError( T t , Exception e );
/** Returns the size of the pool's queue.
* @return pool size
*/
public int queueSize(){
return _queue.size();
}
/** Adds a new object to the pool, if possible.
* @param t the object to be added
* @return if the object was successfully added
*/
public boolean offer( T t ){
if ( ( _queue.size() > 0 || _inProgress.get() == _threads.size() ) &&
_threads.size() < _maxThreads )
_threads.add( new MyThread() );
return _queue.offer( t );
}
public int inProgress(){
return _inProgress.get();
}
public int numThreads(){
return _threads.size();
}
class MyThreadGroup extends ThreadGroup {
MyThreadGroup(){
super( "ThreadPool.MyThreadGroup:" + _name );
}
public void uncaughtException( Thread t, Throwable e ){
for ( int i=0; i<_threads.size(); i++ ){
if ( _threads.get( i ) == t ){
_threads.remove( i );
break;
}
}
}
}
class MyThread extends Thread {
MyThread(){
super( _myThreadGroup , "ThreadPool.MyThread:" + _name + ":" + _threads.size() );
setDaemon( true );
start();
}
public void run(){
while ( true ){
T t = null;
try {
t = _queue.take();
}
catch ( InterruptedException ie ){
}
if ( t == null )
continue;
try {
_inProgress.incrementAndGet();
handle( t );
}
catch ( Exception e ){
handleError( t , e );
}
finally {
_inProgress.decrementAndGet();
}
}
}
}
final String _name;
final int _maxThreads;
private final AtomicInteger _inProgress = new AtomicInteger(0);
private final List<MyThread> _threads = new Vector<MyThread>();
private final BlockingQueue<T> _queue;
private final MyThreadGroup _myThreadGroup;
}