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#pragma once
#include <cassert>
#include <condition_variable>
#include <cstdlib>
#include <mutex>
namespace nix {
/* This template class ensures synchronized access to a value of type
T. It is used as follows:
struct Data { int x; ... };
Sync<Data> data;
{
auto data_(data.lock());
data_->x = 123;
}
Here, "data" is automatically unlocked when "data_" goes out of
scope.
*/
template <class T, class M = std::mutex>
class Sync {
private:
M mutex;
T data;
public:
Sync() {}
explicit Sync(const T& data) : data(data) {}
explicit Sync(T&& data) noexcept : data(std::move(data)) {}
class Lock {
private:
Sync* s;
std::unique_lock<M> lk;
friend Sync;
explicit Lock(Sync* s) : s(s), lk(s->mutex) {}
public:
Lock(Lock&& l) : s(l.s) { abort(); }
Lock(const Lock& l) = delete;
~Lock() {}
T* operator->() { return &s->data; }
T& operator*() { return s->data; }
void wait(std::condition_variable& cv) {
assert(s);
cv.wait(lk);
}
template <class Rep, class Period>
std::cv_status wait_for(
std::condition_variable& cv,
const std::chrono::duration<Rep, Period>& duration) {
assert(s);
return cv.wait_for(lk, duration);
}
template <class Rep, class Period, class Predicate>
bool wait_for(std::condition_variable& cv,
const std::chrono::duration<Rep, Period>& duration,
Predicate pred) {
assert(s);
return cv.wait_for(lk, duration, pred);
}
template <class Clock, class Duration>
std::cv_status wait_until(
std::condition_variable& cv,
const std::chrono::time_point<Clock, Duration>& duration) {
assert(s);
return cv.wait_until(lk, duration);
}
};
Lock lock() { return Lock(this); }
};
} // namespace nix
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