threadpool.h

This software aims to create an applet and panel tools to manage a wireless interface card, such as

//
// ThreadPool.h
//
// $Id: //poco/Main/Foundation/include/Foundation/ThreadPool.h#5 $
//
// Definition of the ThreadPool class.
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#ifndef Foundation_ThreadPool_INCLUDED
#define Foundation_ThreadPool_INCLUDED


#ifndef Foundation_Foundation_INCLUDED
#include "Foundation/Foundation.h"
#endif
#ifndef Foundation_Mutex_INCLUDED
#include "Foundation/Mutex.h"
#endif
#ifndef STD_VECTOR_INCLUDED
#include <vector>
#define STD_VECTOR_INCLUDED
#endif


Foundation_BEGIN


class Runnable;
class PooledThread;


class Foundation_API ThreadPool
	/// A thread pool always keeps a number of threads running, ready
	/// to accept work.
	/// Creating and starting a threads can impose a significant runtime
	/// overhead to an application. A thread pool helps to improve
	/// the performance of an application by reducing the number
	/// of threads that have to be created (and destroyed again).
	/// Threads in a thread pool are re-used once they become
	/// available again.
	/// The thread pool always keeps a minimum number of threads
	/// running. If the demans for threads increases, additional
	/// threads are created. Once the demand for threads sinks
	/// again, no-longer used threads are stopped and removed
	/// from the pool.
{
public:
	ThreadPool(int minCapacity = 2, int maxCapacity = 16, int idleTime = 60);
	ThreadPool(const std::string& name, int minCapacity = 2, int maxCapacity = 16, int idleTime = 60);
		/// Creates a thread pool with minCapacity threads.
		/// If required, up to maxCapacity threads are created
		/// a NoThreadAvailableException exception is thrown.
		/// If a thread is running idle for more than idleTime seconds,
		/// and more than minCapacity threads are running, the thread
		/// is killed.

	~ThreadPool();
		/// Currently running threads will remain active
		/// until they complete. 
	
	void addCapacity(int n);
		/// Increases (or decreases, if n is negative)
		/// the maximum number of threads.

	int capacity() const;
		/// Returns the maximum capacity of threads.

	int used() const;
		/// Returns the number of currently used threads.

	int allocated() const;
		/// Returns the number of currently allocated threads.

	int available() const;
		/// Returns the number available threads.

	void start(Runnable& target);
		/// Obtains a thread and starts the target.
		/// Throws a NoThreadAvailableException if no more
		/// threads are available.

	void stopAll();
		/// Stops all running threads.
		/// Will also delete all thread objects.
		/// If used, this method should be the last action before
		/// the thread pool is deleted.

	void joinAll();
		/// Waits for all threads to complete.

	void collect();
		/// Stops and removes no longer used threads from the
		/// thread pool. Can be called at various times in an
		/// application's life time to help the thread pool
		/// manage its threads. Calling this method is optional,
		/// as the thread pool is also implicitly managed in
		/// calls to start(), addCapacity() and waitAll().

	static ThreadPool& defaultPool();
		/// Returns a reference to the default
		/// thread pool.

protected:
	PooledThread* getThread();
	PooledThread* createThread();

	void housekeep();

private:
	ThreadPool(const ThreadPool& pool);
	ThreadPool& operator = (const ThreadPool& pool);

	typedef std::vector<PooledThread*> ThreadVec;

	std::string _name;
	int _minCapacity;
	int _maxCapacity;
	int _idleTime;
	int _serial;
	ThreadVec _threads;
	mutable FastMutex _mutex;
};


Foundation_END


#endif // Foundation_ThreadPool_INCLUDED