On 20/04/2021 5:27 am, Joost Kraaijeveld wrote:
In short my program: - creates an io_service - calls acceptor::async_accept - calls io_service.run - handle several connections OK - calls io_service.stop - the acceptor goes out of scope (i.e. the destructor of the owning object is ran) - calls io_service.restart - calls acceptor::async_accept which then throws "Operation cancelled"
Should it be possible to do this? When/under what circumstances does async_accept throw this exception?
Yes, that's normal. Async operations are typically automatically cancelled when the related I/O object is destroyed, but the callback is still queued. But it can't actually run until you have a thread running the I/O service. This is part of why it's usually recommended to pass a shared_ptr to your owning object into callbacks, to keep them alive longer than the I/O object itself. (There is *always* a callback at the end of every async operation. Even if just to say that it was cancelled.) io_service.stop() simply stops the thread pool, it doesn't do anything else. When you start it again then any previously queued callbacks will be able to execute.