Re: [PATCH v3 0/8] commit-reach: terminate merge-base walk when one side is exhausted

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 26, 2026, 16:36 UTC
Message-ID: <xmqqjyrl8di0.fsf@gitster.g>
In-Reply-To: <pull.2149.v3.git.1782479286.gitgitgadget@gmail.com>

"Kristofer Karlsson via GitGitGadget" <gitgitgadget@gmail.com> writes:

Show 35 quoted lines

> Changes since v2:
>
>  * New patch 8/8: moved the min_generation termination check and the
>    last_gen monotonicity assertion into paint_queue_get(), consolidating
>    halt conditions. commit_graph_generation() is now called once per
>    dequeued commit and shared across all checks.
>
>  * Widened the generation-monotonicity BUG assertion to fire
>    unconditionally, not only when min_generation is set. The side-exhaustion
>    optimization depends on correct generation ordering, so the assertion
>    should always be active. This is a behavior change: the BUG() now fires
>    for any generation ordering violation, regardless of the caller.
>
>  * Moved all halt conditions inside paint_queue_get() with the "pop first"
>    form: pop, check, then decrement counters. This keeps the optimization
>    commit's diff minimal (just inserting the new checks between pop and
>    decrement).
>
>  * Shortened the doc comment on paint_queue_get() to describe what it does
>    rather than how. Inline comments on each return NULL explain the specific
>    halt condition.
>
>  * Replaced the manual commit-graph setup in the step-count test with
>    run_all_modes, which now sets GIT_TRACE2_EVENT per mode and produces
>    trace-mode-{none,full,half,no-gdat}.txt files.
>
>  * Added a test_paint_down_steps helper for concise 4-mode step assertions
>    with diagnostic output on mismatch (prints "expected X, got Y" instead of
>    a silent grep failure).
>
>  * Added step-count assertions to the single-walk edge-case tests:
>    in_merge_bases_many:self, pending-stale, infinity-both-sides,
>    mixed-finite-infinity.
>
>  * Included step counts alongside wall-clock times in the benchmark tables.

I am getting this failure standalone, when applied on the same base as where v2 was applied earlier. For now I'll eject it from 'seen'.

expecting success of 6600.12 'get_merge_bases_many': 
        cat >input <<-\EOF &&
        A:commit-5-7
        X:commit-4-8
        X:commit-6-6
        X:commit-8-3
        EOF
        {
                echo "get_merge_bases_many(A,X):" &&
                git rev-parse commit-5-6 \
                              commit-4-7 | sort
        } >expect &&
        test_all_modes get_merge_bases_many

BUG: commit-reach.c:152: bad generation skip 9 > 8 at 772be737f220103f706a39013c0d115009feefec
not ok 12 - get_merge_bases_many
#
#               cat >input <<-\EOF &&
#               A:commit-5-7
#               X:commit-4-8