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Inherited from posix::basic_descriptor.
Asynchronously wait for the descriptor 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 descriptor 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 descriptor 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 asio::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 post.
              
void(asio::error_code)
void wait_handler(const asio::error_code& error) { if (!error) { // Wait succeeded. } } ... asio::posix::stream_descriptor descriptor(my_context); ... descriptor.async_wait( asio::posix::stream_descriptor::wait_read, wait_handler);
          This asynchronous operation supports cancellation for the following cancellation_type
          values:
        
cancellation_type::terminal
            cancellation_type::partial
            cancellation_type::total