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//
// Copyright 2019 Ettus Research, a National Instruments brand
//
// SPDX-License-Identifier: GPL-3.0-or-later
//
#include <condition_variable>
#include <chrono>
#include <mutex>
#ifndef INCLUDED_UHDLIB_UTILS_SEMAPHORE_HPP
# define INCLUDED_UHDLIB_UTILS_SEMAPHORE_HPP
namespace uhd {
/*!
* A sempahore built using std::condition_variable
*/
class semaphore
{
public:
void notify()
{
std::unique_lock<std::mutex> lock(_cv_mutex);
_count++;
_cv.notify_one();
}
void wait()
{
std::unique_lock<std::mutex> lock(_cv_mutex);
_cv.wait(lock, [this]() { return this->_count != 0; });
_count--;
}
bool try_wait()
{
std::unique_lock<std::mutex> lock(_cv_mutex);
if (_count != 0) {
_count--;
return true;
}
return false;
}
bool wait_for(size_t timeout_ms)
{
std::chrono::milliseconds timeout(timeout_ms);
std::unique_lock<std::mutex> lock(_cv_mutex);
if (_cv.wait_for(lock, timeout, [this]() { return this->_count != 0; })) {
_count--;
return true;
}
return false;
}
size_t count()
{
std::unique_lock<std::mutex> lock(_cv_mutex);
return _count;
}
private:
std::condition_variable _cv;
std::mutex _cv_mutex;
size_t _count = 0;
};
} // namespace uhd
#endif /* INCLUDED_UHDLIB_UTILS_SEMAPHORE_HPP */
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