Cancel any asynchronous operations that are waiting on the timer.
std::size_t cancel( boost::system::error_code & ec);
This function forces the completion of any pending asynchronous wait operations against the timer. The handler for each cancelled operation will be invoked with the boost::asio::error::operation_aborted error code.
Cancelling the timer does not change the expiry time.
Set to indicate what error occurred, if any.
The number of asynchronous operations that were cancelled.