Re: client_side and comm_close

On Fri, 2008-04-18 at 16:15 +0800, Adrian Chadd wrote:
> On Wed, Apr 16, 2008, Alex Rousskov wrote:
>
> > In short, we have several related problems here: (a) client_side code is
> > incapable of reliably identifying whether comm_close has been called;
> > (b) ConnStateData::isOpen may not work anymore; (c) client_side code
> > uses many different ways to identify whether more data should be read
> > from the connection; (d) comm_close is used a lot but no longer has an
> > immediate effect and some client_side code may still depend on that
> > effect to be immediate; (e) client_side comm handlers decent very deep,
> > making it difficult to propagate errors and comm_close status up.
> >
> > We should decide whether to continue patching holes here and there or
> > clean up the client_side*cc connection management mess for good. Should
> > we continue to patch isolated v3.0 problems and cleanup v3.1? Or is this
> > a v3.2 project? Or am I exaggerating the problems since common cases
> > usually work fine?
>
> I'd suggest another option - roll back all of the async calls changes to the
> comm code, stabilise the codebase without it and re-evaluate what should
> occur (in smaller chunks, rather than dropping in a new comm manager)
> before reintroducing it.

If the client_side's main problem was a few coding bugs caused by async
call changes, you may have been right. Unfortunately, our main problem
here is the client_side design flaws. Removing async calls from comm
will not undo those flaws.

The changes needed on the client-side are pretty much unrelated to async
calls. Async calls just make the design problems more obvious and help
in solving them. Removing async calls from comm will fix a few bugs, but
will be a step backwards and will make ongoing code cleanup more
difficult.

Another way to look at it is to note that client_side was already pretty
stable before async calls (i.e., Squid 3.0). Thus, we have already been
where you are proposing to go.

Alex.
Received on Tue Apr 22 2008 - 15:08:32 MDT