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//
// copyright            : (C) 2008 by Eran Ifrah                            
// file name            : jobqueue.h              
//                                                                          
// -------------------------------------------------------------------------
// A                                                                        
//              _____           _      _     _ _                            
//             /  __ \         | |    | |   (_) |                           
//             | /  \/ ___   __| | ___| |    _| |_ ___                      
//             | |    / _ \ / _  |/ _ \ |   | | __/ _ )                     
//             | \__/\ (_) | (_| |  __/ |___| | ||  __/                     
//              \____/\___/ \__,_|\___\_____/_|\__\___|                     
//                                                                          
//                                                  F i l e                 
//                                                                          
//    This program is free software; you can redistribute it and/or modify  
//    it under the terms of the GNU General Public License as published by  
//    the Free Software Foundation; either version 2 of the License, or     
//    (at your option) any later version.                                   
//                                                                          
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 #ifndef __jobqueue__
#define __jobqueue__

#include <wx/thread.h>
#include <deque>
#include <vector>

class Job;

/**
 * @class JobQueueWorker
 * @author Eran
 * @date 05/09/08
 * @file jobqueue.h
 * @brief a thread class used internally by JobQueue
 * @sa JobQueue 
 */
class JobQueueWorker : public wxThread
{
	wxCriticalSection *m_cs;
	std::deque<Job*> *m_queue;
	
public:
	/// default ctor/dtor
	JobQueueWorker(wxCriticalSection *cs, std::deque<Job*> *queue);
	virtual ~JobQueueWorker();

private:
	//declare this class as non copyable
	JobQueueWorker(const JobQueueWorker& rhs);
	JobQueueWorker& operator=(const JobQueueWorker& rhs);
	
public:
	/**
	 * @brief stop the running thread. usually called before calling JobQueue::Release()
	 */
	void Stop();
	
	/**
	 * @brief start the thread with given priority
	 * @param priority thread priority (defaulted to WXTHREAD_DEFAULT_PRIORITY)
	 */
	void Start(int priority = WXTHREAD_DEFAULT_PRIORITY);
	
	
	/**
	 * @brief implementation of the wxThread pure virtual function Entry()
	 * @sa wxThread 
	 */
	virtual void* Entry();
	
	/**
	 * @brief return a job to process from the queue. 
	 * @return Jon to process or NULL if queue is empty. 
	 */
	Job *GetJob();
	
	/**
	 * @brief the main code that processes the job
	 * @param job job to process
	 * @sa Job 
	 */
	virtual void ProcessJob(Job *job);
};

/**
 * @class JobQueue 
 * @author Eran
 * @date 05/09/08
 * @file jobqueue.h
 * @brief this class provides a convenient way of handling background tasks using Job objects
 * 
 * @code
 * // somewhere in your application initialization 
 * // start the job queue with 5 workers and default thread prioritization
 * m_jobQueue = new JobQueue();
 * m_jobQueue->Start(5); 
 * 
 * // whenever you need to add new job to be processed 
 * // just add it
 * m_jobQueue->PushJob( new MyJob() );
 * 
 * // Shutdown code:
 * m_jobQueue->Stop();
 * // free the resources allocated by the JobQueue and empty the queue 
 * delete m_jobQueue;
 * @endcode 
 * 
 */ 
class JobQueue 
{
	wxCriticalSection m_cs;
	std::deque<Job*> m_queue;
	std::vector<JobQueueWorker*> m_threads;
		
public:
	JobQueue();
	virtual ~JobQueue();

	/**
	 * @brief add job to the queue. all jobs must be constructed on the heap.
	 * note that the job will be freed when processing is done by the job queue 
	 * @param job job to process allocated on the heap
	 */
	virtual void PushJob(Job *job);
	
	/**
	 * @brief 
	 * @param poolSize
	 * @param priority
	 */
	virtual void Start(size_t poolSize = 1, int priority = WXTHREAD_DEFAULT_PRIORITY);
	
	/**
	 * @brief stop all workers threads
	 */
	virtual void Stop();
};

/**
 * @class JobQueueSingleton
 * @author Eran
 * @date 05/09/08
 * @file jobqueue.h
 * @brief a wrapper around the JobQueue class that provides the functionality of singleton
 */
class JobQueueSingleton 
{
private:
	static JobQueue *ms_instance;
	
private:
	JobQueueSingleton();
	virtual ~JobQueueSingleton();
	
public:
	/**
	 * @brief 
	 * @return 
	 */
	static JobQueue *Instance();
	
	/**
	 * @brief 
	 */
	static void Release();
};
#endif // __jobqueue__
