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