Re: [PATCH 3/3] pkt-line: support tracing verbatim pack contents

Augie Fackler [off-list ref] writes:

On Fri, Jun 12, 2015 at 5:28 PM, Jeff King [off-list ref] wrote:

quoted

When debugging the pack protocol, it is sometimes useful to
store the verbatim pack that we sent or received on the
wire. Looking at the on-disk result is often not helpful for
a few reasons:

  1. If the operation is a clone, we destroy the repo on
     failure, leaving nothing on disk.

  2. If the pack is small, we unpack it immediately, and the
     full pack never hits the disk.

  3. If we feed the pack to "index-pack --fix-thin", the
     resulting pack has the extra delta bases added to it.

We already have a GIT_TRACE_PACKET mechanism for tracing
packets. Let's extend it with GIT_TRACE_PACK to dump the
verbatim packfile.

FWIW, this also works for me - I have no preference between my patches
and Jeff's. I suspect yours are much better given that you have a clue
about git internals ;).

One bit of feedback is that it might be worth mentioning (though I
don't feel strongly) that GIT_TRACE_PACK works with or without
GIT_TRACE_PACKET - that wasn't immediately obvious to me, but it makes
sense once I read the code.

Thanks!

Thanks, both.  I think this series makes sense.

As to the documentation, I have a feeling that, unless the reader
and/or the user intimately knows that TRACE_PACK is implemented by
hooking into the same mechanism that TRACE_PACKET needs to, s/he
would not even wonder if TRACE_PACKET needs to be enabled when
asking for TRACE_PACK.  Yes, one is a proper substring of the other,
but the similarity between the two stops there.  While I do not
think it would hurt very much to mention that they are independent,
I have a slight suspicion that it might make it more likely to get
user confused.