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/********************************************************************************
* *
* C o m p l e t i o n C o u n t e r *
* *
*********************************************************************************
* Copyright (C) 2014,2022 by Jeroen van der Zijp. All Rights Reserved. *
*********************************************************************************
* This library is free software; you can redistribute it and/or modify *
* it under the terms of the GNU Lesser General Public License as published by *
* the Free Software Foundation; either version 3 of the License, or *
* (at your option) any later version. *
* *
* This library 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 Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/> *
********************************************************************************/
#ifndef FXCOMPLETION_H
#define FXCOMPLETION_H
namespace FX {
class FXThreadPool;
/**
* A completion counter allows a single thread to monitor a number of ongoing
* concurrent activities for completion. Each activity calls increment() on the
* completion counter when started, and decrement() when finished.
* The monitoring thread can call wait(), wait(nsec), or done() to determine
* the status of the concurrent activity.
* Only one thread is allowed to call any of the wait() functions; but multiple
* threads can call increment() or decrement().
* The completion counter can not be destroyed until the last thread decrements
* the counter back down to zero.
*/
class FXAPI FXCompletion {
private:
FXSemaphore semaphore; // Signalled when last task done
volatile FXuint counter; // Task counter
private:
FXCompletion(const FXCompletion&);
FXCompletion& operator=(const FXCompletion&);
public:
/// Initialize completion counter
FXCompletion();
/// Return current counter value
FXuint count() const { return counter; }
/// Increment counter by cnt
void increment(FXuint cnt=1);
/// Decrement counter by cnt
void decrement(FXuint cnt=1);
/// Wait till count becomes zero again
void wait();
/// Wait till count becomes zero, or timeout; return false if timed out
FXbool wait(FXTime nsec);
/// Return true if count is zero
FXbool done() const { return (counter==0); }
/// Wait till count becomes zero, then destroy
~FXCompletion();
};
}
#endif
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