semaphore.h

/*
 * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All Rights Reserved.
 * Author: GreenSocs 2022
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
 
#ifndef SEMAPHORE_H
#define SEMAPHORE_H
 
namespace gs {
 
#include <mutex>
#include <condition_variable>
 
class semaphore
{
private:
    std::mutex mutex_;
    std::condition_variable condition_;
    unsigned long count_ = 0; // Initialized as locked.
 
public:
    void notify()
    {
        std::lock_guard<decltype(mutex_)> lock(mutex_);
        ++count_;
        condition_.notify_one();
    }
 
    void wait()
    {
        std::unique_lock<decltype(mutex_)> lock(mutex_);
        while (!count_) // Handle spurious wake-ups.
            condition_.wait(lock);
        --count_;
    }
 
    bool try_wait()
    {
        std::lock_guard<decltype(mutex_)> lock(mutex_);
        if (count_) {
            --count_;
            return true;
        }
        return false;
    }
 
    semaphore() = default;
    ~semaphore()
    {
        // don't block on destruction
        notify();
    }
};
} // namespace gs
 
#endif // SEMAPHORE_H