Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Constructor to set a particular expiry time relative to now.

basic_deadline_timer(
    const executor_type & ex,
    const duration_type & expiry_time);

This constructor creates a timer and sets the expiry time.

ex: The I/O executor that the timer will use, by default, to dispatch handlers for any asynchronous operations performed on the timer.
expiry_time: The expiry time to be used for the timer, relative to now.