(Happy to accept a PR. The relevant code is in `messageLoop()` and `RpcConnectionState::disconnect()` in `rpc.c++`.)
On Wed, Sep 27, 2023 at 2:05 PM Kenton Varda <[email protected]> wrote: > Indeed, there isn't really a clean shutdown mechanism right now. I guess > it hasn't come up as a priority because in most use cases we just haven't > really cared if there's a TCP RST triggered under the hood... since we're > already killing the connection, we ignore that error anyway. > > I suppose what we should do is, in the case that we receive a clean EOF, > inhibit the sending of an abort message back, just send EOF back. > > -Kenton > > On Thu, Sep 21, 2023 at 6:09 PM 'Alex' via Cap'n Proto < > [email protected]> wrote: > >> Hi all, >> >> I am designing an application (in C++) where, upon invocation of a >> particular RPC call, both the server and the client agree to cleanly >> disconnect from one another. By "cleanly", I mean that both the server >> and the client send a TCP FIN/ACK and nothing more (e.g. no RSTs). >> Unfortunately, in the current design the receipt of a FIN will cause >> AsyncIoMessageStream::tryReadMessage() to abort, whereupon it will >> throw KJ_EXCEPTION(DISCONNECTED, "Peer disconnected.")[0]. This >> exception is eventually written to the client socket, and if the client >> is already gone, there will be one or more RSTs in response: >> >> C -> S: "Goodbye" (RPC call) >> C -> S: "I have nothing more to say" (TCP FIN) >> >> (the client does not expect the server to say anything more and closes >> the socket) >> >> S -> C: "Exception! You disconnected from me" (RPC message) >> C -> S: "Error: Connection reset by peer" (TCP RST) >> >> Given that both the server and client have agreed to shut down the >> connection, this is not an exceptional circumstance. Therefore, an >> exception should not be thrown. >> >> Unfortunately, there does not seem to be a way to indicate to the >> RpcSystem that the DISCONNECTED exception ought to be suppressed. Is >> there something I am missing? I appreciate any assistance. >> >> Regards, >> Alex >> >> [0] >> https://github.com/capnproto/capnproto/blob/761aeb17563a59f43b3fe9bae93df83c6bd57d06/c%2B%2B/src/capnp/rpc.c%2B%2B#L2775 >> >> -- >> 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/20230921190853.115b911d%40centromere.net >> . >> > -- 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/CAJouXQkvmFfnXVLR6M8itZeog4KrXLFXmaFiQw8ZxSxOfOyFMw%40mail.gmail.com.
