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[/
/ Copyright (c) 2003-2013 Christopher M. Kohlhoff (chris at kohlhoff dot com)
/
/ Distributed under the Boost Software License, Version 1.0. (See accompanying
/ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[section:timers Timers]
Long running I/O operations will often have a deadline by which they must have
completed. These deadlines may be expressed as absolute times, but are often
calculated relative to the current time.
As a simple example, to perform a synchronous wait operation on a timer using a
relative time one may write:
io_service i;
...
deadline_timer t(i);
t.expires_from_now(boost::posix_time::seconds(5));
t.wait();
More commonly, a program will perform an asynchronous wait operation on a
timer:
void handler(boost::system::error_code ec) { ... }
...
io_service i;
...
deadline_timer t(i);
t.expires_from_now(boost::posix_time::milliseconds(400));
t.async_wait(handler);
...
i.run();
The deadline associated with a timer may also be obtained as a relative time:
boost::posix_time::time_duration time_until_expiry
= t.expires_from_now();
or as an absolute time to allow composition of timers:
deadline_timer t2(i);
t2.expires_at(t.expires_at() + boost::posix_time::seconds(30));
[heading See Also]
[link boost_asio.reference.basic_deadline_timer basic_deadline_timer],
[link boost_asio.reference.deadline_timer deadline_timer],
[link boost_asio.reference.deadline_timer_service deadline_timer_service],
[link boost_asio.tutorial.tuttimer1 timer tutorials].
[endsect]
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