Re: [PATCH 07/11] Resumable clone: add resumable download to http/curl
- From
- Kevin Wern <kevin.m.wern@gmail.com>
- Date
- Sep 28, 2016, 06:41 UTC
- Message-ID
- <20160928064156.GG3762@kwern-HP-Pavilion-dv5-Notebook-PC>
- In-Reply-To
- <xmqqfuozihuv.fsf@gitster.mtv.corp.google.com>
On Fri, Sep 16, 2016 at 03:45:44PM -0700, Junio C Hamano wrote:
Show 13 quoted lines
> > @@ -1136,7 +1138,10 @@ static int handle_curl_result(struct slot_results *results) > > curl_easy_strerror(results->curl_result), > > sizeof(curl_errorstr)); > > #endif > > - return HTTP_ERROR; > > + if (results->http_code >= 400) > > + return HTTP_ERROR; > > + else > > + return HTTP_ERROR_RESUMABLE; > > } > > } > > Hmm, is "anything below 400" a good definition of resumable errors?
Definitely a rough definition, but I think it covers the majority of cases. I based this on the fact that my example resumable errors (disconnections during download) either had results->http_code set to 206 or 0, and that http errors generally indicate some underlying issue that can't be solved with a repeat request (there are plenty of exceptions, such as 503 or 504 errors that happen intermittently). I thought that was enough to be a placeholder in the model. I did consider something like "has (the file changed size or http_code been 206, some indication of success happened) in the last [x] attempts," but I question the precision of something like that, especially before exploring other tried-and-true solutions.
This patch is definitely the sketchiest part of my series, IMO. The concept isn't fleshed out enough, even theoretically--containing only the element of retrying with some very basic components to those decisions. I think that this will ultimately require fishing through other examples of resumable downloads (which was very painful to read when I tried). I know curl has a --retry option, but doesn't include it in libcurl...harumph. I'll probably try to read that implementation and chromium's resumable download code again.
I'll get back to you with a better plan here once I read through a few examples.
- Kevin