[swift-server-dev] HTTP Parser

Helge Heß me at helgehess.eu
Fri Nov 4 16:18:23 CDT 2016


On 4 Nov 2016, at 21:20, Paulo Faria <paulo at zewo.io> wrote:
> Logan, would you be kind to explain why you think we shouldn’t touch C?

Well, I think the rational is pretty clear. Staying within a single language has obvious benefits. Add to that safety features inherent to Swift designed solutions (buffer overruns and such) as well as the relative beauty of a modern language.

http_parser is a very C thing, it makes extensive use of pointers, goto’s and other C ‘tricks' to accomplish the performance it has. It is reasonably small and focused code but certainly not code which is straight forward to read&understand.

At the same time http_parser is a nice demo on how a high performance C core implementation is used in a high-level language environment (Node.js). The user of Node.js doesn’t have to deal with the C stuff at all.

Anyways I stick to my original opinion:
—snip---
Personally I’d suggest a small wrapper around this one: https://github.com/nodejs/http-parser
—snap—

But if someone has a great Swift parser providing the key features I’m interested in (push based, as zero copy as possible, reasonably fast), I’m quite interested too :->

hh


> My argument is that using a C library that we all know works well gives us time to work on more important things, like the user-facing API. You mentioned that we all like Swift because it’s safe, succinct and clean. I think we can all agree with that, but that statement doesn’t correlate to using a C lib. We wouldn’t be _implementing_ the parser in c, we would be _using_ a existing c parser. So the work would fall into what we’ll already have to do when dealing with C POSIX APIs, for example. Using a C lib would be one less thing to maintain. So again we can focus on creating safe, succinct and clean code where it really matters, the API level.
> 
> 
>> On Nov 4, 2016, at 5:18 PM, Logan Wright via swift-server-dev <swift-server-dev at swift.org> wrote:
>> 
>> Helge, if I had my way, we wouldn't touch C in any way whatsoever for any of the server side libraries except as an absolute last resort, but this life is full of compromise, and I'm trying to be amicable to come up with solutions that we can agree on.
>> 
>> For HTTP2 as well, I'd like plans to eventually move to pure swift native implementations rethought for the language. 
>> 
>> On Fri, Nov 4, 2016 at 3:17 PM Helge Heß via swift-server-dev <swift-server-dev at swift.org> wrote:
>> On 4 Nov 2016, at 20:11, Logan Wright via swift-server-dev <swift-server-dev at swift.org> wrote:
>> > That said, even if we do end up doing that short term, I'd like to include plans or at least intentions to do things in Swift. I (and I'm sure many of us) generally prefer working in Swift because it's safe, succinct, and clean. We also have several instances of existing HTTP parsers we could pull from, it's not like we're starting from 0 as a group.
>> >
>> > For HTTP2, I think everyone is in agreement that a c library is the way to go. I'd like to give HTTP a bit more time for opinions to come in.
>> 
>> I’m not entirely sure why you have double standards here. Why would you come up with a safe, succinct and clean HTTP/1.x parser but not do the same for HTTP/2?
>> 
>> hh
>> 
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