basic_seq_packet_socket::cancel (1 of 2 overloads)

-basic_seq_packet_socket::cancel - (1 of 2 overloads) -

- Inherited from basic_socket. -

- Cancel all asynchronous operations associated with the socket. -

void cancel();
-

- This function causes all outstanding asynchronous connect, send and receive - operations to finish immediately, and the handlers for cancelled operations - will be passed the boost::asio::error::operation_aborted - error. -

- - Exceptions -

boost::system::system_error: - Thrown on failure. -

- - Remarks -

- Calls to cancel() - will always fail with boost::asio::error::operation_not_supported - when run on Windows XP, Windows Server 2003, and earlier versions of - Windows, unless BOOST_ASIO_ENABLE_CANCELIO is defined. However, the CancelIo - function has two issues that should be considered before enabling its - use: -

- It will only cancel asynchronous operations that were initiated in - the current thread. -
- It can appear to complete without error, but the request to cancel - the unfinished operations may be silently ignored by the operating - system. Whether it works or not seems to depend on the drivers that - are installed. -

- For portable cancellation, consider using one of the following alternatives: -

- Disable asio's I/O completion port backend by defining BOOST_ASIO_DISABLE_IOCP. -
- Use the close() - function to simultaneously cancel the outstanding operations and - close the socket. -

- When running on Windows Vista, Windows Server 2008, and later, the CancelIoEx - function is always used. This function does not have the problems described - above. -