Rather than using a context() member function, query the executor's
execution::context_t property to obtain its associated execution
context:
asio::execution_context& context
= asio::query(my_io_executor, asio::execution::context);
When using standard executors, work is tracked by requiring (or
preferring) an executor with the execution::outstanding_work.tracked
property. This replaces executor_work_guard and make_work_guard() with
code of the form
asio::io_context io_context;
auto work = asio::require(io_context.get_executor(),
asio::execution::outstanding_work.tracked);
To explicitly reset work, store the returned work-tracking executor in
an any_io_executor object:
asio::any_io_executor work
= asio::require(io_context.get_executor(),
asio::execution::outstanding_work.tracked);
and then assign an empty executor into the object when done:
work = asio::any_io_executor();
All I/O objects now have an additional Executor template parameter. This
template parameter defaults to the asio::executor type (the polymorphic
executor wrapper) but can be used to specify a user-defined executor
type.
I/O objects' constructors and functions that previously took an
asio::io_context& now accept either an Executor or a reference to a
concrete ExecutionContext (such as asio::io_context or
asio::thread_pool).
One potential point of breakage in existing user code is when reusing an
I/O object's io_context for constructing another I/O object, as in:
asio::steady_timer my_timer(my_socket.get_executor().context());
To fix this, either construct the second I/O object using the first I/O
object's executor:
asio::steady_timer my_timer(my_socket.get_executor());
or otherwise explicitly pass the io_context:
asio::steady_timer my_timer(my_io_context);
N.B. The Windows-specific tick_count_timer example has been removed as
it has been superseded by timers based on the standard steady_clock.
It's also not clear how to map a wrapping time source to the standard
chrono concepts.
Define BOOST_ASIO_USE_BOOST_DATE_TIME_FOR_SOCKET_IOSTREAM to enable the
old Boost.Date_Time interface in basic_socket_streambuf and
basic_socket_iostream.
* Use asio::steady_timer rather than asio::deadline_timer.
* Use asio::dynamic_buffer rather than asio::streambuf.
* Use timed asio::io_context::run_for() function for blocking clients.
* Add example showing a custom completion token for blocking with timeouts.
