citra/src/common/thread.h

// Copyright 2013 Dolphin Emulator Project / 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#pragma once

#include <atomic>
#include <chrono>
#include <condition_variable>
#include <cstddef>
#include <mutex>
#include <thread>

namespace Common {

class Event {
public:
    void Set() {
        std::lock_guard lk{mutex};
        if (!is_set) {
            is_set = true;
            condvar.notify_one();
        }
    }

    void Wait() {
        std::unique_lock lk{mutex};
        condvar.wait(lk, [&] { return is_set.load(); });
        is_set = false;
    }

    template <class Duration>
    bool WaitFor(const std::chrono::duration<Duration>& time) {
        std::unique_lock lk{mutex};
        if (!condvar.wait_for(lk, time, [this] { return is_set.load(); }))
            return false;
        is_set = false;
        return true;
    }

    template <class Clock, class Duration>
    bool WaitUntil(const std::chrono::time_point<Clock, Duration>& time) {
        std::unique_lock lk{mutex};
        if (!condvar.wait_until(lk, time, [this] { return is_set.load(); }))
            return false;
        is_set = false;
        return true;
    }

    void Reset() {
        std::unique_lock lk{mutex};
        // no other action required, since wait loops on the predicate and any lingering signal will
        // get cleared on the first iteration
        is_set = false;
    }

private:
    std::condition_variable condvar;
    std::mutex mutex;
    std::atomic_bool is_set{false};
};

class Barrier {
public:
    explicit Barrier(std::size_t count_) : count(count_) {}

    /// Blocks until all "count" threads have called Sync()
    void Sync() {
        std::unique_lock lk{mutex};
        const std::size_t current_generation = generation;

        if (++waiting == count) {
            generation++;
            waiting = 0;
            condvar.notify_all();
        } else {
            condvar.wait(lk,
                         [this, current_generation] { return current_generation != generation; });
        }
    }

    std::size_t Generation() const {
        std::unique_lock lk(mutex);
        return generation;
    }

private:
    std::condition_variable condvar;
    mutable std::mutex mutex;
    std::size_t count;
    std::size_t waiting = 0;
    std::size_t generation = 0; // Incremented once each time the barrier is used
};

void SetCurrentThreadName(const char* name);

} // namespace Common