I think I figured out the first two problems. Multiple inheritance worked out quite nicely, only downside is each simulator needs to be defined explicitly. I think I found the correct way to do threading, which seems to be to use kj::getCurrentThreadExecutor() to get a way to schedule callbacks on the eventloop thread. So I guess you'd pass a promise to the thread and then fulfill it using the executor. https://github.com/capnproto/capnproto/blob/master/kjdoc/tour.md#threads As with most of these things, they are quite puzzling at first but actually quite nice once you figure them out.
So the only problem left is how to handle disconnects in extremely long running processes. Cheers, Pepijn On Thursday, 18 March 2021 at 12:18:50 UTC+1 [email protected] wrote: > Hey, > > I'm designing an RPC server for simulators that can run several different > long-running commands, and I have a few design questions. > > My current design is as follows. > Upon loading files to simulate, the simulator returns a list of unions of > interfaces, representing all the simulation commands it supports. > Upon calling one of the commands, a reader interface is returned that > allows streaming simulation results. > This currently happens in-thread, so reading big chunks will block the > entire server. > > So first question is, is there a nicer way to represent a thing that can > implement a subset of functions? I could just define a mega interface and > not implement methods, but then the issue is how to discover which methods > the server implements. Or maybe the correct approach is to use multiple > inheritance from the smaller interfaces to concrete implementations? > > The next question is how to offload the simulation to a thread? I assumed > this would be a very common task but I can't find much in the docs. I found > KJ::Thread or something like that, but it's not clear to me how to tie that > into the event loop promise API. > > Final issue I'm thinking about, for *very* long running simulations, the > client disconnecting in the middle of simulation that takes days or weeks > becomes a real concern. This is basically level 2 of > https://capnproto.org/rpc.html#protocol-features but as far as I > understand C++ is only level 1. What would be a good way to go about things > here? If level 2 is just around the corner, I can just ignore the issue for > a while, but maybe I need to manually store simulator references outside > the connection and hand out tokens to it? > > Regards, > Pepijn > -- You received this message because you are subscribed to the Google Groups "Cap'n Proto" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/capnproto/8fe36a3a-88dd-4761-9fa9-48ba90a1da0fn%40googlegroups.com.
