PR27859 PATCH: correct 404-latch in connection reuse

[Mark Wielaard]

Hi Frank,

On Fri, May 14, 2021 at 06:51:17PM -0400, Frank Ch. Eigler via Elfutils-devel wrote:
> (I'll deploy this fix to one of the public servers to confirm it there.)

Thanks. If that looks good, please commit.

> Author: Frank Ch. Eigler <fche@redhat.com>
> Date:   Fri May 14 18:37:30 2021 -0400
> 
>     PR27859: correct 404-latch bug in debuginfod client reuse
>     
>     PR27701 implemented curl handle reuse in debuginfod_client objects,
>     but with an unexpected bug.  Server responses returning an error
>     "latched" because the curl_easy handles for error cases weren't all
>     systematically removed from the curl multi handle.  This prevented
>     their proper re-addition the next time.
>     
>     This version of the code simplfies matters by making only the curl
>     curl_multi handle long-lived.  This turns out to be enough, because it
>     can maintain a pool of long-lived http/https connections and related
>     data, and lend them out to short-lived curl_easy handles.  This mode
>     handles errors or hung downloads even better, because the easy handles
>     don't undergo complex state transitions between reuse.
>     
>     A new test case confirms this correction via the federating debuginfod
>     instance (cleaning caches between subtests to make sure http* is being
>     used and reused).

It is nice that the multi code works that way, it makes things a bit
simpler and less state to keep around for the debuginfod_client
handle. The changes look good to me. And the new testcase passes here.

Cheers,

Mark