Re: Fix potential hang in https handshake.

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Jeff King <peff@xxxxxxxx> writes:

> On Fri, Oct 19, 2012 at 07:10:46AM -0700, Shawn O. Pearce wrote:
>
>> > IOW, it seems like we are _already_ following the advice referenced in
>> > curl's manpage. Is there some case I am missing? Confused...
>> 
>> The issue with the current code is sometimes when libcurl is opening a
>> CONNECT style connection through an HTTP proxy it returns a crazy high
>> timeout (>240 seconds) and no fds. In this case Git waits forever.
>> Stefan observed that using a timeout of 50 ms in this situation to
>> poll libcurl is better, as it figures out a lot more quickly that it
>> is connected to the proxy and can issue the request.
>
> Ah. That sounds like a bug in curl to me. But either way, if we want to
> work around it, wouldn't the right thing be to override curl's timeout
> in that instance? Like:

Yeah, that sounds like a more targetted workaround (read: better).

>
> diff --git a/http.c b/http.c
> index df9bb71..cd07cdf 100644
> --- a/http.c
> +++ b/http.c
> @@ -631,6 +631,19 @@ void run_active_slot(struct active_request_slot *slot)
>  			FD_ZERO(&excfds);
>  			curl_multi_fdset(curlm, &readfds, &writefds, &excfds, &max_fd);
>  
> +			/*
> +			 * Sometimes curl will give a really long timeout for a
> +			 * CONNECT when there are no fds to read, but we can
> +			 * get better results by running curl_multi_perform
> +			 * more frequently.
> +			 */
> +			if (maxfd < 0 &&
> +			    (select_timeout.tv_sec > 0 ||
> +			     select_timeout.tv_usec > 50000)) {
> +				select_timeout.tv_sec = 0;
> +				select_timeout.tv_usec = 50000;
> +			}
> +
>  			select(max_fd+1, &readfds, &writefds, &excfds, &select_timeout);
>  		}
>  	}
>
> -Peff
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