Re: [PATCH v2 3/4] bisect--helper: reimplement `bisect_run` shell function in C

From: "Miriam R." <mirucam@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git <git@vger.kernel.org>
Subject: Re: [PATCH v2 3/4] bisect--helper: reimplement `bisect_run` shell function in C
Date: Sun, 11 Apr 2021 12:04:25 +0200	[thread overview]
Message-ID: <CAN7CjDD02yjB2QX2VQxfVie6OchkVLfH3Hog8s1jXZw5uDDTzg@mail.gmail.com> (raw)
In-Reply-To: <xmqqeeflycf9.fsf@gitster.g>

El jue, 8 abr 2021 a las 0:09, Junio C Hamano (<gitster@pobox.com>) escribió:
>
> Miriam Rubio <mirucam@gmail.com> writes:
>
> > From: Tanushree Tumane <tanushreetumane@gmail.com>
> >
> > Reimplement the `bisect_run()` shell function
> > in C and also add `--bisect-run` subcommand to
> > `git bisect--helper` to call it from git-bisect.sh.
> >
> > Mentored-by: Christian Couder <chriscool@tuxfamily.org>
> > Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
> > Signed-off-by: Miriam Rubio <mirucam@gmail.com>
>
> If I am reading the patch correctly, this removes the need for the
> $GIT_DIR/BISECT_RUN file that used to be used to keep track of the
> state?  If that is true, it is worth noting in the proposed log
> message.
>
> As far as I can see, nobody creates $GIT_DIR/BISECT_RUN anymore.
>
>     $ git grep -e path_bisect_run -e BISECT_RUN
>     bisect.c:static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
>     bisect.c:   unlink_or_warn(git_path_bisect_run());
>     builtin/bisect--helper.c:           BISECT_RUN,
>     builtin/bisect--helper.c:                    N_("use <cmd>... to automatical...
>     builtin/bisect--helper.c:   case BISECT_RUN:
>     t/t6030-bisect-porcelain.sh:        test_path_is_missing ".git/BISECT_RUN" &&
>
> What if a run script tried to read from (or checked the presence of)
> the file for its correct operation (e.g. I would imagine that "do
> this operation when run interactively, but do the same operation
> silently when run from the git-bisect machinery" may be a reasonable
> thing to do)?
>
> This change just unintendedly broke such a script, didn't it?  The
> change makes me a bit worried.
Hi,
thank you for reviewing!.
I don't know why the need for the $GIT_DIR/BISECT_RUN file was
removed, so in the last patch series version I have just sent,
I have added the creation of the file and it contains bisect_state()
output as in original shell script version.
Regards,
Miriam
>
> > +     if (bisect_next_check(terms, NULL))
> > +             return BISECT_FAILED;
> > +
> > +     if (argc)
> > +             sq_quote_argv(&command, argv);
> > +     else
> > +             return BISECT_FAILED;
> > +
> > +     run_args.v[0] = xstrdup(command.buf);
> > +     run_args.nr = 1;
> > +
> > +     while (1) {
> > +             strvec_clear(&args);
> > +
> > +             printf(_("running %s"), command.buf);
> > +             res = run_command_v_opt(run_args.v, RUN_USING_SHELL);
>
> Nicely used sq_quote_argv() with RUN_USING_SHELL here.  Goodl.
>
> > +             if (res < 0 && res >= 128) {
> > +                     error(_("bisect run failed: exit code %d from"
> > +                             " '%s' is < 0 or >= 128"), res, command.buf);
> > +                     strbuf_release(&command);
> > +                     return res;
> > +             }
> > +
> > +             if (res == 125)
> > +                     strvec_push(&args, "skip");
> > +             else if (res > 0)
> > +                     strvec_push(&args, terms->term_bad);
> > +             else
> > +                     strvec_push(&args, terms->term_good);
> > +
>
> bisect_state() does so much that it was a bit hard to follow for me
> (who hasn't been following the bisect-in-C topic very closely), but
> the code around here roughly corresponds to the following snippet in
> the original scripted version.
>
> > -             git bisect--helper --bisect-state $state >"$GIT_DIR/BISECT_RUN"
> > -             res=$?
> > -
> > -             cat "$GIT_DIR/BISECT_RUN"
> > -
> > -             if sane_grep "first $TERM_BAD commit could be any of" "$GIT_DIR/BISECT_RUN" \
> > -                     >/dev/null
> > -             then
> > -                     gettextln "bisect run cannot continue any more" >&2
> > -                     exit $res
> > -             fi
>
> I see that the contents of the file BISECT_RUN is shown to the user
> in the original but is that part of what bisect_state() does, or did
> we lose it during this round of conversion?
>
> > +             res = bisect_state(terms, args.v, args.nr);
> > +             if (res == BISECT_INTERNAL_SUCCESS_MERGE_BASE) {
> > +                     printf(_("bisect run success"));
> > +                     res = BISECT_OK;
> > +             } else if (res == BISECT_ONLY_SKIPPED_LEFT)
> > +                     error(_("bisect run cannot continue any more"));
> > +             else if (res)
> > +                     error(_("bisect run failed:'git bisect--helper --bisect-state"
> > +                             " %s' exited with error code %d"), args.v[0], res);
> > +             else
> > +                     continue;
>
> In any case, being able to check the return value from bisect_state()
> and switch is so much nicer than having to sane_grep in BISECT_RUN.
>
> > +             strbuf_release(&command);
> > +             strvec_clear(&args);
> > +             strvec_clear(&run_args);
> > +
> > +             return res;
> > +     }
> > +}
> > +
> >  int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
> >  {
> >       enum {
> > @@ -1086,7 +1146,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
> >               BISECT_LOG,
> >               BISECT_REPLAY,
> >               BISECT_SKIP,
> > -             BISECT_VISUALIZE
> > +             BISECT_VISUALIZE,
> > +             BISECT_RUN,
>
> Now this new one has the trailing comma.  I'd suggest doing so in
> the previous step.
>
> Thanks.