...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 pong control frame asynchronously.
template< class PongHandler = net::default_completion_token_t<executor_type>> DEDUCED async_pong( ping_data const& payload, PongHandler&& handler = net::default_completion_token_t< executor_type >{});
This function is used to asynchronously send a pong frame, which is usually sent automatically in response to a ping frame from the remote 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 pong frame is sent, the
error received by this completion handler will be net::error::operation_aborted
.
WebSocket allows pong frames to be sent at any time, without first receiving a ping. An unsolicited pong sent in this fashion may indicate to the remote peer that the connection is still active.
Name |
Description |
---|---|
|
The payload of the pong 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 );
If the handler has an associated immediate executor, an immediate
completion will be dispatched to it. Otherwise, the handler will
not be invoked from within this function. Invocation of the handler
will be performed by dispatching to the immediate executor. If
no immediate executor is specified, this is 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.