On Thu, Dec 24, 2020 at 6:35 AM Artur Vianna <lordhowen...@gmail.com> wrote:
> Exposing the bytes would hurt the abstraction.
>
I strongly disagree with this. Exposing the bytes would improve the
abstraction, by making the transmission- and encoding method orthogonal.
And as I said, you can still provide just as convenient a wrapper around it.
> I will certainly look into Json and maybe MessagePack. But first i may
> fiddle with the gob source code, if my sanity allows it. If i can control
> when the type information is sent i may be able to fix this without
> changing the API. The ideal enconding would be a stateless gob, with the
> proper decoding/encoding "machines" set on either side when you call
> gob.Register, but i'm not sure of the feasibility of that.
>
Sure, that's definitely possible. I factored that in, when I said "I think
it's far less effort to just use a different format than trying to make
this work with gob".
But, of course, you do you. :) The decision of what API to expose and what
encoding scheme to use and how much work you are putting into what piece is
ultimately up to you :)
>
> On Wed, 23 Dec 2020, 21:55 Axel Wagner, <axel.wagner...@googlemail.com>
> wrote:
>
>> On Thu, Dec 24, 2020 at 1:08 AM Artur Vianna <lordhowen...@gmail.com>
>> wrote:
>>
>>> Before using gob was using encoding.BinaryMarshaler, but that would mean
>>> the user of the api would need to implement a MarshalBinary for every type,
>>> which is kind of cumbersome.
>>>
>>
>>> An option might be to let the user choose gob, BinaryMarshaler or Json
>>> etc to best fit the use case, but that takes the simplicity of only gobs
>>> away.
>>>
>>
>> I am all in favor of API simplicity, but gob just isn't super useful for
>> this. Not to repeat myself, but you should really at least try JSON - it
>> provides exactly the same convenience as gob, but doesn't suffer these
>> problems. It might have a bit more overhead and might even be costlier to
>> encode - but the savings from being able to eliminate duplicate effort
>> should offset that (and I'm not even super convinced - I don't think gob is
>> the most well-optimized encoding in the stdlib).
>>
>> But IMO, if you provide an API, the best solution is to a) just use
>> `[]byte` at the base-layer and then b) provide convenience-wrappers around
>> that for other formats. This lets the users decide what they want (they
>> might want something completely different anyway) while still providing a
>> decently convenient API for simple uses.
>>
>>
>>>
>>> I did try your solution to reset the client too but i'm getting
>>> inconsistent behaviour, in one server it works and in another it doesn't
>>> ("corrupted data or unknown type"). I think synching the server and client
>>> will be error prone, while also increasing the use of network.
>>>
>>> The easiest solution now is to label the package for ≤32 players and
>>> test alternative encodings that keep the API as clean as with gob. I took a
>>> look at flatbuffers but it will be cumbersome for the user to create the
>>> builders, and i really wanted the simplest possible API.
>>>
>>> Maybe i should try UDP Broadcast too and see what happens, probably
>>> chaos :D
>>>
>>>
>>> On Wed, 23 Dec 2020, 20:36 Axel Wagner, <axel.wagner...@googlemail.com>
>>> wrote:
>>>
>>>> No, it wouldn't. Because the encoder keeps state about which
>>>> type-information it already sent and wouldn't sent it again - causing the
>>>> client to be unable to decode. So you'd also need a new encoder on the
>>>> server. And at that point, you're back to the status quo, with one encoder
>>>> per client and the duplication of encoding effort.
>>>>
>>>> A solution would, perhaps, be if the gob API would give you a way to
>>>> send *only* the type-info (so you could, if the connection breaks, create a
>>>> new encoder, send all the type info, and *then* multicast the encoded
>>>> values). But it doesn't.
>>>>
>>>> Really, I think it's far less effort to just use a different format
>>>> (and I would maintain that even json would probably be fine) than trying to
>>>> make this work with gob :)
>>>>
>>>> On Thu, Dec 24, 2020 at 12:20 AM Matthew Zimmerman <
>>>> mzimmer...@gmail.com> wrote:
>>>>
>>>>> 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?
>>>>>>>>>> Not allowing two encoders on the server for one decoder on the
>>>>>>>>>> client?
>>>>>>>>>>
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>>>>>>>>>> .
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