ManualEvent.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 <array>
#include <condition_variable>
 
namespace ctre {
namespace phoenix {
namespace threading {
    /**
     * Manual Event object, useful for signaling
     * other threads about an event.
     */
    class CTREXPORT ManualEvent {
    private:
        size_t _signal;
        mutable std::mutex _m;
        mutable std::condition_variable _cv;
 
    public:
        /**
         * \param initialSignal whether this event defaults to signaled
         */
        ManualEvent(bool initialSignal = false);
 
        /**
         * Wait for event to be signaled, or for timeout.
         * \param timeoutMs timeout of the wait; -1 is indefinite, 0 is a fast check
         * \returns true if event is signaled, false if timed out
         */
        bool WaitForSignal(int timeoutMs) const;
 
        /**
         * Waits for all events to be signaled, or for timeout.
         * \param timeoutMs timeout of the wait; -1 is indefinite, 0 is a fast check
         * \param minTimeoutMs when timeoutMs > 0, minimum amount of time to wait for
         *                     a signal; this can be used to ensure that a non-zero
         *                     timeout is used for every signal; typically 0 or 1 ms
         * \param events comma-separated list of event references to wait on
         * \returns true if all events are signaled, false if timed out
         */
        template < typename... Event, typename = std::enable_if_t<std::conjunction_v<std::is_same<Event, ManualEvent>...>> >
        static bool WaitForAllSignals(int timeoutMs, int minTimeoutMs, Event &... events)
        {
            std::array eventsArr{(&events)...};
            return WaitForAllSignals(timeoutMs, minTimeoutMs, eventsArr.data(), eventsArr.size());
        }
 
        /**
         * Waits for all events to be signaled, or for timeout.
         * \param timeoutMs timeout of the wait; -1 is indefinite, 0 is a fast check
         * \param minTimeoutMs when timeoutMs > 0, minimum amount of time to wait for
         *                     a signal; this can be used to ensure that a non-zero
         *                     timeout is used for every signal; typically 0 or 1 ms
         * \param events pointer to an array of event pointers to wait on
         * \param eventCnt number of events in the array
         * \returns true if all events are signaled, false if timed out
         */
        static bool WaitForAllSignals(int timeoutMs, int minTimeoutMs, ManualEvent *const *events, size_t eventCnt);
 
        /**
         * Signal the event. Any threads waiting on WaitForSignal() will return true.
         */
        void Signal();
        /**
         * Clear the event signal without signaling other threads.
         */
        void Clear();
        /**
         * Reset the event signal to false and force any threads waiting on WaitForSignal() to time out.
         */
        void Reset();
    };
}
}
}