...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Send a websocket ping control frame asynchronously.
template< class WriteHandler = net::default_completion_token_t<executor_type>> DEDUCED async_ping( ping_data const& payload, WriteHandler&& handler = net::default_completion_token_t< executor_type >{});
This function is used to asynchronously send a ping frame, which usually elicits an automatic pong control frame response from the peer.
The algorithm, known as a composed asynchronous operation,
is implemented in terms of calls to the next layer's async_write_some
function. The program must ensure that no other calls to ping
, pong
, async_ping
, or async_pong
are performed until
this operation completes. If a close frame is sent or received before the
ping frame is sent, the error received by this completion handler will
be net::error::operation_aborted
.
Name |
Description |
---|---|
|
The payload of the ping message, which may be empty. The implementation will not access the contents of this object after the initiating function returns. |
|
The completion handler to invoke when the operation completes. The implementation takes ownership of the handler by performing a decay-copy. The equivalent function signature of the handler must be: void handler( error_code const& ec // Result of operation );
Regardless of whether the asynchronous operation completes immediately
or not, the handler will not be invoked from within this function.
Invocation of the handler will be performed in a manner equivalent
to using |
This asynchronous operation supports cancellation for the following net::cancellation_type values:
net::cancellation_type::terminal
net::cancellation_type::total
total
cancellation succeeds
if the operation is suspended due to ongoing control operations such as
a ping/pong. terminal
cancellation
succeeds when supported by the underlying stream. terminal
cancellation leaves the stream in an undefined state, so that only closing
it is guaranteed to succeed.