std::atomic<std::chrono::high_resolution_clock::time_point> can not compile

Question

I need std::chrono::high_resolution_clock::time_point field which I want to write from one thread and read from another thread. If I declare it as is my code compiles without any errors.

But to make my field visible in another thread I surround it with std::atomic like this std::atomic<std::chrono::high_resolution_clock::time_point> and now I have following compilation error:

/usr/include/c++/4.8/atomic:167:7: error: function ‘std::atomic<_Tp>::atomic() [with _Tp = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1l, 1000000000l> > >]’ defaulted on its first declaration with an exception-specification that differs from the implicit declaration ‘constexpr std::atomic<std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1l, 1000000000l> > > >::atomic()’
       atomic() noexcept = default;

How should I declare std::chrono::high_resolution_clock::time_point field which I write from one thread and read from another (to make sure that "reading thread" sees last value)?

Answer 1

Your choices:

• forget about making it atomic and use a mutex to serialise access

• pick some integral unit of time (e.g. milliseconds since epoch) and convert to/from that on the fly, storing the integral value in some integral type you've worked out has sufficient capacity to cover the range of dates you're handling (perhaps std::atomic_ullong)

• (nutty suggestion removed)