If you would "reset" each client with a new decoder each time you make a new encoder, everything should work fine. Just would take some coordination.
On Wed, Dec 23, 2020, 6:08 PM Artur Vianna <lordhowen...@gmail.com> wrote: > I will look into other protocols, although for now the performance is not > an issue in servers with less than 100 players. > > The problem with io.MultiWriter is that a player inside the group may > disconnect or a new player may come in. This means a new io.MultiWriter > must be created each time you dispatch, since the group may have changed in > the meantime. This would also need a new encoder and then the "duplicate > type received" happens. > > On Wed, 23 Dec 2020, 19:58 'Axel Wagner' via golang-nuts, < > golang-nuts@googlegroups.com> wrote: > >> The issue with that approach is that gob keeps state about which >> type-information it still has to send. So if you encode to, say, a >> bytes.Buffer, it would encode all type-info on every message sent, which is >> a significant overhead. >> TBH, I don't understand why `io.MultiWriter` wouldn't work. It would be >> helpful to see the code that causes the error message OP is seeing. >> >> However, really, gob just doesn't provide a good API for this sorta >> thing, as mentioned. The format itself is fine, but the stateful connection >> means that if you don't want to write *exactly* the same data in exactly >> the same order to all connections (which can perform poorly and lead to >> operational problems with timeouts and intermittently lost connections and >> the like), you are going to have a bad time. >> You honestly would fare better with a full-fledged RPC framework such as >> gRPC. Or, if you don't want the overhead of its IDL, even json. Because at >> least the "encode once, send to each client" is trivial to solve with that. >> >> But, that's just my 2¢ :) >> >> On Wed, Dec 23, 2020 at 11:43 PM Robert Engels <reng...@ix.netcom.com> >> wrote: >> >>> Yes, that is why you need to create your own protocol. Use the gob to >>> encode to a buffer then send the buffer on each of the connections using >>> your protocol. >>> >>> On Dec 23, 2020, at 4:19 PM, Matthew Zimmerman <mzimmer...@gmail.com> >>> wrote: >>> >>> >>> My understanding is that gob streams are unique. >>> >>> From https://golang.org/pkg/encoding/gob/ >>> "A stream of gobs is self-describing. Each data item in the stream is >>> preceded by a specification of its type, expressed in terms of a small set >>> of predefined types." >>> >>> In my own rudimentary understanding/terms, it sends the struct >>> definition once, then uses shorthand for it afterwards. E.g, how many >>> bytes and what order. If you mix and match streams that send definitions >>> in different orders, then chaos ensues. >>> >>> I think this is why people use other encoders in the scenario you're >>> taking about. For a one to one stream gob works great, but in this multi >>> scenario I don't think it does. >>> >>> Matt >>> >>> On Wed, Dec 23, 2020, 5:07 PM Artur Vianna <lordhowen...@gmail.com> >>> wrote: >>> >>>> If i create a bytes.Buffer and a gob.Encoder, each time i write to a >>>> group of connections i get "duplicate type received" and if i try and reuse >>>> the encoder, i get "corrupted data" and "unknown type". >>>> It seems i can't use both net.Conn.Write and gob.Encoder.Encode in the >>>> same connection, i will try always encoding to a buffer in both unicast and >>>> multicast like you said and report if it works. >>>> >>>> On Wed, 23 Dec 2020, 18:49 Robert Engels, <reng...@ix.netcom.com> >>>> wrote: >>>> >>>>> You need to encode once to a byte array then send the byte array on >>>>> each connection. >>>>> >>>>> On Dec 23, 2020, at 3:45 PM, meera <lordhowen...@gmail.com> wrote: >>>>> >>>>> >>>>> I am trying to create a package for game servers using gob. The >>>>> current approach is an application level multicasting over TCP, having a >>>>> gob encoder and decoder for each player connection, and set up a goroutine >>>>> to receive and another to dispatch for each one. The code for the >>>>> dispatcher is here. But summarized, it simply receives data from a channel >>>>> and encodes it. >>>>> >>>>> The problem is that if i want to transmit a single piece of data to >>>>> all players, this piece of data is encoded again and again for each >>>>> connection, doing duplicate work. With less than 100 players this is not a >>>>> problem, but with 300+ my machine is at almost 100% usage and the profiler >>>>> shows that most of it is spent on encoding. Here's the issue on github. >>>>> >>>>> I tryied using a io.MultiWriter but gob complains of duplicate type >>>>> received, and if i try to write the raw bytes from the gob.Encoder i get >>>>> corrupted data. An option is using UDP Broadcasting but since gob expects >>>>> a >>>>> stream, i'm affraid i will run into unexpected behavior when packets start >>>>> to be lost and fragmented. >>>>> >>>>> Does gob expect a single encoder and decoder to own the stream? 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