Subject: [PATCH v1 0/3] trace2 output for bitmap decision path

From: Teng Long <[email-masked]>
Date: Thu, 24 Mar 2022 19:43:58 +0800

A Git repo can be chosen to use the normal bitmap (before MIDX) and MIDX bitmap.

I recently tried to understand this part of the MIDX implementation because I found
a bug which has been discovered and repaired in community [1].

I am grateful to Taylor Blau for his help and for introducing me to the testing
method according to the `git rev-list --test-bitmap <rev>`.

In the process of understanding and troubleshooting by using this command, I found
when the execution is failed it will output a single line of
"fatal: failed to load bitmap indexes", sometimes will be more informations like
if the bitmap file is broken, the outputs maybe contain
"error: Corrupted bitmap index file (wrong header)".), but most of time are single
line output I mentioned above. So, this brings a little obstacle for debugging and
troubleshooting I think, because "failed to load bitmap indexes" can represent
to much informations (many causes like: midx config turn off, bitmap inexistence, etc.)

Therefore, as a git repo can be chosen to use the normal bitmap (before MIDX) or
MIDX bitmap, or they can both exist and let git make the decision. I think why not add
some extra informations based on TRACE2 to help for showing the bitmap decision path
clearer and more plentiful, so when the failure occurs the user can use it to debug
around bitmap in a quicker way.

Thanks.

Links:
	1. https://public-inbox.org/git/[email-masked]/)

Teng Long (3):
  pack-bitmap.c: use "ret" in "open_midx_bitmap()"
  pack-bitmap.c: add "break" statement in "open_pack_bitmap()"
  bitmap: add trace outputs during open "bitmap" file

 midx.c        |  2 ++
 pack-bitmap.c | 17 +++++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

Range-diff against v0:
-:  ---------- > 1:  3048b4dd29 pack-bitmap.c: use "ret" in "open_midx_bitmap()"
-:  ---------- > 2:  70500b6343 pack-bitmap.c: add "break" statement in "open_pack_bitmap()"
-:  ---------- > 3:  9912450fc1 bitmap: add trace outputs during open "bitmap" file
-- 
2.35.1.579.g70500b6343.dirty