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Each non-stale queued commit occupies exactly one counter bucket based on its paint flags: PARENT1-only, PARENT2-only, or both sides (a pending merge-base candidate). The counters are maintained by paint_count_update() which adjusts the appropriate bucket by a signed delta. An exhaustive switch on the paint+stale bits documents all valid flag combinations in one place. Convert paint_down_to_common() to use paint_state. The loop now drains the queue via paint_queue_get() which returns NULL when all counters reach zero, replacing the old pointer-based termination (max_nonstale). This is equivalent behavior -- both conditions detect that no non-stale entries remain. paint_queue_get() uses a "pop first" form: it dequeues a commit, then checks the counters. This means the loop exits one iteration earlier than the old code in some topologies (the popped stale commit is never processed), so a few step counts drop by one. The existing nonstale_queue is left in place for ahead_behind(). Signed-off-by: Kristofer Karlsson --- .../technical/paint-down-to-common.adoc | 9 +- commit-reach.c | 94 ++++++++++++++++--- t/t6600-test-reach.sh | 4 +- 3 files changed, 85 insertions(+), 22 deletions(-) diff --git a/Documentation/technical/paint-down-to-common.adoc b/Documentation/technical/paint-down-to-common.adoc index a4dfcba038..ac3e2b39a5 100644 --- a/Documentation/technical/paint-down-to-common.adoc +++ b/Documentation/technical/paint-down-to-common.adoc @@ -88,15 +88,12 @@ re-enqueued is bounded by the number of flag transitions. Termination ----------- -The walk uses a `nonstale_queue` wrapper around `prio_queue` that -tracks `max_nonstale`: the lowest-priority non-stale commit enqueued -so far. Once that commit is dequeued, every remaining entry is known -to be STALE and the loop terminates. Specifically, the main loop +The walk tracks the number of commits of each type in the queue +(PARENT1-only, PARENT2-only, pending merge-base). The main loop ends when one of the following conditions holds: 1. The queue is empty. - 2. `max_nonstale` has been dequeued, meaning the queue only contains - STALE entries. + 2. The queue contains only stale entries. 3. Generation cutoff: the dequeued commit's generation is below a caller-supplied `min_generation` threshold. 4. Single result: the caller only needs one merge base, one has diff --git a/commit-reach.c b/commit-reach.c index f6a438550b..9ae306f60c 100644 --- a/commit-reach.c +++ b/commit-reach.c @@ -97,6 +97,75 @@ static struct commit *nonstale_queue_get_dedup(struct nonstale_queue *queue) return commit; } +/* + * Priority queue with per-side commit counters for paint_down_to_common(). + * Each non-stale queued commit occupies exactly one bucket: PARENT1-only, + * PARENT2-only, or both (a pending merge-base candidate). + */ +struct paint_state { + struct prio_queue queue; + size_t parent1_count; + size_t parent2_count; + size_t mb_candidate_count; +}; + +static void paint_count_update(struct paint_state *state, + unsigned flags, int delta) +{ + switch (flags & (PARENT1 | PARENT2 | STALE)) { + case PARENT1: + state->parent1_count += delta; + break; + + case PARENT2: + state->parent2_count += delta; + break; + + case PARENT1 | PARENT2: + state->mb_candidate_count += delta; + break; + + case PARENT1 | PARENT2 | STALE: + break; + + default: + BUG("unexpected paint state"); + } +} + +static void paint_queue_put(struct paint_state *state, + struct commit *c, unsigned add_flags) +{ + unsigned old_flags = c->object.flags; + c->object.flags |= add_flags; + + if (old_flags & ENQUEUED) { + paint_count_update(state, old_flags, -1); + paint_count_update(state, c->object.flags, 1); + } else { + c->object.flags |= ENQUEUED; + prio_queue_put(&state->queue, c); + paint_count_update(state, c->object.flags, 1); + } +} + +static struct commit *paint_queue_get(struct paint_state *state) +{ + struct commit *commit = prio_queue_get(&state->queue); + + if (!commit) + return NULL; + + commit->object.flags &= ~ENQUEUED; + + if (!state->parent1_count && !state->parent2_count && + !state->mb_candidate_count) + return NULL; + + paint_count_update(state, commit->object.flags, -1); + return commit; +} + /* * See Documentation/technical/paint-down-to-common.adoc * @@ -109,31 +178,29 @@ static int paint_down_to_common(struct repository *r, enum merge_base_flags mb_flags, struct commit_list **result) { - struct nonstale_queue queue = { - { compare_commits_by_gen_then_commit_date } + struct paint_state state = { + .queue = { compare_commits_by_gen_then_commit_date } }; + struct commit *commit; int i; int steps = 0; timestamp_t last_gen = GENERATION_NUMBER_INFINITY; struct commit_list **tail = result; if (!min_generation && !corrected_commit_dates_enabled(r)) - queue.pq.compare = compare_commits_by_commit_date; + state.queue.compare = compare_commits_by_commit_date; one->object.flags |= PARENT1; if (!n) { commit_list_append(one, result); return 0; } - nonstale_queue_put_dedup(&queue, one); + paint_queue_put(&state, one, 0); - for (i = 0; i < n; i++) { - twos[i]->object.flags |= PARENT2; - nonstale_queue_put_dedup(&queue, twos[i]); - } + for (i = 0; i < n; i++) + paint_queue_put(&state, twos[i], PARENT2); - while (queue.max_nonstale) { - struct commit *commit = nonstale_queue_get_dedup(&queue); + while ((commit = paint_queue_get(&state))) { struct commit_list *parents; int flags; timestamp_t generation = commit_graph_generation(commit); @@ -172,7 +239,7 @@ static int paint_down_to_common(struct repository *r, if ((p->object.flags & flags) == flags) continue; if (repo_parse_commit(r, p)) { - clear_nonstale_queue(&queue); + clear_prio_queue(&state.queue); commit_list_free(*result); *result = NULL; /* @@ -187,12 +254,11 @@ static int paint_down_to_common(struct repository *r, return error(_("could not parse commit %s"), oid_to_hex(&p->object.oid)); } - p->object.flags |= flags; - nonstale_queue_put_dedup(&queue, p); + paint_queue_put(&state, p, flags); } } - clear_nonstale_queue(&queue); + clear_prio_queue(&state.queue); trace2_data_intmax("paint_down_to_common", r, "steps", steps); commit_list_sort_by_date(result); diff --git a/t/t6600-test-reach.sh b/t/t6600-test-reach.sh index b3a31b80ac..51f3d70492 100755 --- a/t/t6600-test-reach.sh +++ b/t/t6600-test-reach.sh @@ -289,7 +289,7 @@ test_expect_success 'get_merge_bases_many:pending-stale' ' git rev-parse ps-B } >expect && test_all_modes get_merge_bases_many && - test_paint_down_steps 6 6 6 6 + test_paint_down_steps 5 5 5 5 ' test_expect_success 'get_merge_bases_many:infinity-both-sides' ' @@ -304,7 +304,7 @@ test_expect_success 'get_merge_bases_many:infinity-both-sides' ' git rev-parse pi-B } >expect && test_all_modes get_merge_bases_many && - test_paint_down_steps 5 5 5 5 + test_paint_down_steps 5 4 5 5 ' test_expect_success 'setup mixed finite/INFINITY topology' ' -- gitgitgadget