...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Asynchronously wait for the socket to become ready to read, ready to write, or to have pending error conditions.
template< typename WaitToken = default_completion_token_t<executor_type>> DEDUCED async_wait( wait_type w, WaitToken && token = default_completion_token_t< executor_type >());
This function is used to perform an asynchronous wait for a socket to enter a ready to read, write or error condition state. It is an initiating function for an asynchronous operation, and always returns immediately.
Specifies the desired socket state.
The completion
token that will be used to produce a completion handler, which
will be called when the wait completes. Potential completion tokens
include use_future
, use_awaitable
, yield_context
, or a function
object with the correct completion signature. The function signature
of the completion handler must be:
void handler( const boost::system::error_code& error // Result of operation. );
Regardless of whether the asynchronous operation completes immediately
or not, the completion handler will not be invoked from within this
function. On immediate completion, invocation of the handler will
be performed in a manner equivalent to using async_immediate
.
void(boost::system::error_code)
void wait_handler(const boost::system::error_code& error) { if (!error) { // Wait succeeded. } } ... boost::asio::ip::tcp::socket socket(my_context); ... socket.async_wait(boost::asio::ip::tcp::socket::wait_read, wait_handler);
On POSIX or Windows operating systems, this asynchronous operation supports
cancellation for the following cancellation_type
values:
cancellation_type::terminal
cancellation_type::partial
cancellation_type::total