|
Start an asynchronous operation to wait for a signal to be delivered.
template< typename SignalToken = default_completion_token_t<executor_type>> DEDUCED async_wait( SignalToken && token = default_completion_token_t< executor_type >());
This function may be used to initiate an asynchronous wait against the signal set. It is an initiating function for an asynchronous operation, and always returns immediately.
For each call to async_wait(), the completion handler will be called
exactly once. The completion handler will be called when:
asio::error::operation_aborted.
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 asio::error_code& error, // Result of operation. int signal_number // Indicates which signal occurred. );
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(asio::error_code, int)
This asynchronous operation supports cancellation for the following cancellation_type
values:
cancellation_type::terminal
cancellation_type::partial
cancellation_type::total
Unlike the POSIX function signal,
async_wait executes its
completion handler as specified in the asynchronous
operation requirements. This means it places no async-signal safety
restrictions on what work can be performed in a completion handler.