(Deprecated: Use range overload.) Asynchronously establishes a socket connection by trying each endpoint in a sequence.
template< typename Protocol, typename Iterator, typename ConnectCondition, typename IteratorConnectHandler> DEDUCED async_connect( basic_socket< Protocol > & s, Iterator begin, ConnectCondition connect_condition, IteratorConnectHandler && handler, typename enable_if<!is_endpoint_sequence< Iterator >::value >::type * = 0);
This function attempts to connect a socket to one of a sequence of endpoints.
It does this by repeated calls to the socket's async_connect
member function, once for each endpoint in the sequence, until a connection
is successfully established.
The socket to be connected. If the socket is already open, it will be closed.
An iterator pointing to the start of a sequence of endpoints.
A function object that is called prior to each connection attempt. The signature of the function object must be:
bool connect_condition( const asio::error_code& ec, const typename Protocol::endpoint& next);
The ec
parameter contains the result from the most recent
connect operation. Before the first connection attempt, ec
is always set to indicate success. The next
parameter
is the next endpoint to be tried. The function object should return
true if the next endpoint should be tried, and false if it should
be skipped.
The handler to be called when the connect operation completes. Copies will be made of the handler as required. The function signature of the handler must be:
void handler( // Result of operation. if the sequence is empty, set to // asio::error::not_found. Otherwise, contains the // error from the last connection attempt. const asio::error_code& error, // On success, an iterator denoting the successfully // connected endpoint. Otherwise, the end iterator. Iterator iterator );
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 asio::io_context::post()
.
This overload assumes that a default constructed object of type Iterator
represents the end of the sequence. This is a valid assumption for iterator
types such as asio::ip::tcp::resolver::iterator
.