First time contributor here, trying my first git.git patch series.
BACKGROUND
We have a script that runs a range of build tests for all new commits in the
repository and adds a line to the commit note with the result from the test.
Something along the lines of:
occa-build-jit-gnu-cuda-develop: PASSED (<hostname>, 2024-01-01 00:00:00+01:00)
Pretty useful to quickly check that all commits at least build, not only for
master, but also in progress feature branches. (a passing test suite is
generally only required at the merge point)
PROBLEM
The bash script loops over all remote refs and lists the commits newer than
<N> days ago. For each commit its note is read and grep'ed for an existing
test name to see whether the build test needs to run again. The `git note show`
command that is in this loop nest only takes 14ms to execute, but as it is in
a loop, those times add up.
ANALYSIS
When asked to show a note for a specific commit, git looks up the blob hash
for the note and executes `git show` with that hash. That of course adds
the child process overhead, but also causes the initialization of a lot of
log related configuration, such as for decorations or the mailmap. Simply
outputting the blob directly in the main process reduces the run time by
almost halve.
When looking through the git show implementation for useful stuff that command
does that should also be done when showing a note, I could only find the
`setup_pager()` call and some optional textconv stuff.
The second commit is the main one fixing performance. The others are just
eliminating some overhead I noticed when going through the git notes code.
CHANGES WRT V1
Sharing of the show_blob_object() function from log.c. The intention here is
to have `git notes show` behave the same as `git show` when in the future the
latter might be changed to have more sophisticated behaviour for some blobs,
e.g. launching an image viewer for PNG blobs. Non-blob notes are still not
handled, just like in V1. Current master does handle that, but that is not
deemed a case worth handling.
Maarten Bosmans (5):
log: Move show_blob_object() to log.c
notes: avoid launching a child process to show a note blob
notes: use existing function stream_blob_to_fd
notes: do not clean up right before calling die()
notes: use strbuf_attach to take ownership of the object contents
Makefile | 1 +
builtin/log.c | 39 +++++----------------------------------
builtin/notes.c | 38 +++++++++++---------------------------
log.c | 41 +++++++++++++++++++++++++++++++++++++++++
log.h | 11 +++++++++++
5 files changed, 69 insertions(+), 61 deletions(-)
create mode 100644 log.c
create mode 100644 log.h
--
2.35.3
