workerthread.h

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/*
 *
 * workerthread.h
 *
 *
   Copyright (C) 2006 Michael H. Overlin

   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.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   
   Contact at [e-mail]
 */

#ifndef WORKERTHREAD_H
#define WORKERTHREAD_H

#include <windows.h>


// NOTE:  IF THE WORKER THREAD ACCESSES ANY DATA OTHER THAN DATA WHICH IS PRIVATE TO THE
// DERIVED CLASS, THAT DATA MUST BE SYNCHRONIZED.  FOR EXAMPLE, DATA PASSED INTO ITS CONSTRUCTOR.
// SAME IS TRUE OF ANY OF ITS PRIVATE DATA THAT ARE ACCESSED VIA PUBLIC METHODS (POSSIBLY BY A DIFFERENT THREAD)

class WorkerThread {
public:
	enum {
		eDefaultTimeSliceMS = 50,
		eDefaultTotalWaitMS = INFINITE
	};

	WorkerThread(void);
	// DERIVED CLASS DESTRUCTOR MUST CALL
	// WaitOnTerminate OR PeekMessagesUntilTerminate
	// TO MAKE SURE CLASS IS NOT DESTROYED BEFORE THREAD TERMINATES
	// WorkerThread CAN'T DO THIS, BECAUSE THE VTABLE HAS BEEN REDUCED BY THE TIME
	// ITS DESTRUCTOR IS CALLED, SO THAT DoWork IS NOT THE DERIVED CLASSES DO WORK
	// THIS COULD RESULT IN A PURE VIRTUAL CALL
	virtual ~WorkerThread();

	// AT MOST ONE ADDITIONAL WORKER THREAD PER CLASS INSTANCE IS SUPPORTED BY THIS THREAD
	// AFTER A CALL TO StartNewDoWorkThread, CLIENT MUST CALL WaitOnTerminate OR PeekMessagesUntilTerminate
	// UNTIL THEY RETURN TRUE BEFORE CALLING StartNewDoWorkThread AGAIN
	BOOL StartNewDoWorkThread(void);

	BOOL PeekMessagesUntilTerminate(DWORD dwWaitTimeSlice = eDefaultTimeSliceMS, DWORD dwTotalWaitMS = eDefaultTotalWaitMS);
	BOOL WaitOnTerminate(DWORD dwWaitTimeSliceMS = eDefaultTimeSliceMS);

protected:
	virtual void DoWork(void) = 0;

private:
	HANDLE m_hThread;

	static void __cdecl TheirThreadProc(void *pv);
};

#endif