boost::asio::deadline_timer with std::chrono time values

Question

I have an application that uses asio deadline timers. The rest of the application uses std::chrono constructs for its time values, and it feels awkward to use boost::posix_time for only the stuff that touches asio. I'd like to use std::chrono throughout the application if I can, for consistency, readability, etc.

It seems to me that the answer would involve using the timer's template:

typedef boost::asio::basic_deadline_timer<std::chrono::system_clock::time_point>
    my_deadline_timer_type;
 my_deadline_timer_type a_timer(io_service); 

Except this blows up badly at compile time...many lines of error, most of which are similar to this:

/opt/arm/include/boost/asio/deadline_timer_service.hpp:51:43: error: invalid use of incomplete type 'boost::asio::deadline_timer_service > >, boost::asio::time_traits > > > >::traits_type {aka struct boost::asio::time_traits > > >}'

So, it looks like I may need to create a new traits_type and declare a deadline_timer_service using it, but I'm not sure how/where. I have to believe this problem has been solved. I'm using g++ 4.7.3 with -std=c++11 on linux, cross-compiling to arm.

Answer 1

If you are using boost 1.49 or later, ASIO introduced the basic_waitable_timer, which uses C++11 compatible clocks, either from std::chrono or boost::chrono. They also provided pre-defined typedefs for the boost versions of steady_clock, system_clock, and high_resolution_clock. Its functionality is the same as deadline_timer, but uses the C++11 clock mechanisms instead of the boost::posix_time structures.

For earlier versions, you're going to have to pass a traits structure to handle conversion to the type expected by deadline_timer. See the ASIO TimeTraits requirements. Most are trivial, the last is not. So, for example

template<typename Clock>
struct CXX11Traits
{
  typedef typename Clock::time_point time_type;
  typedef typename Clock::duration   duration_type;
  static time_type now()
  {
      return Clock::now();
  }
  static time_type add(time_type t, duration_type d)
  {
      return t + d;
  }
  static duration subtract(time_type t1, time_type t2)
  {
      return t1-t2;
  }
  static bool less_than(time_type t1, time_type t2)
  {
      return t1 < t2;
  }

  static  boost::posix_time::time_duration 
  to_posix_duration(duration_type d1)
  {
    using std::chrono::duration_cast;
    auto in_sec = duration_cast<std::chrono::seconds>(d1);
    auto in_usec = duration_cast<std::chrono::microseconds>(d1 - in_sec);
    boost::posix_time::time_duration result =
      boost::posix_time::seconds(in_sec.count()) + 
      boost::posix_time::microseconds(in_usec.count());
    return result;
  }
};

You would then create deadline timers for each C++11 clock you want to use. The example here is for std::system_clock. You would use this deadline timer as normal.

typedef boost::asio::basic_deadline_timer< 
        std::system_clock,  
        CXX11Traits<std::system_clock>> my_system_clock_deadline_timer