RcManualEvent.hpp

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/*
 * Copyright (C) Cross The Road Electronics.  All rights reserved.
 * License information can be found in CTRE_LICENSE.txt
 * For support and suggestions contact support@ctr-electronics.com or file
 * an issue tracker at https://github.com/CrossTheRoadElec/Phoenix-Releases
 */
#pragma once
 
#include "ctre/phoenix/export.h"
#include <condition_variable>
 
namespace ctre {
namespace phoenix {
namespace threading {
    /**
     * Reference-counted Manual Event. Each Signal()
     * increments a reference count, and each Clear()
     * decrements the count. The event is signaled while
     * the count is greater than 0.
     *
     * This is useful for a situation where multiple threads
     * signal an operation to run, and the operation should not
     * stop until all threads clear the event.
     */
    class CTREXPORT RcManualEvent {
    private:
        size_t _signal = 0;
        mutable size_t _waitCnt = 0;
        mutable std::mutex _m;
        mutable std::condition_variable _cv;
 
    public:
        /**
         * Wait for event to be signaled, or for timeout
         * \returns true if event is signaled, false if timed out.
         */
        bool WaitForSignal(int timeoutMs) const;
 
        /**
         * Signal the event. Any threads waiting on WaitForSignal() will return true.
         * The caller must clear the signal once it is done, otherwise the reference
         * count may never return to 0.
         */
        void Signal();
        /**
         * Clear the event. Any threads waiting on WaitForSignal() will time out
         * if this is the last thread to clear the signal.
         */
        void Clear();
        /**
         * Reset the event signal to 0 without signaling other threads.
         */
        void Reset();
    };
}
}
}