commit-reach: introduce struct paint_state with per-side counters

index c203f14455..3b3f7ac8af 100644 --- a/Documentation/technical/paint-down-to-common.adoc +++ b/Documentation/technical/paint-down-to-common.adoc @@ -94,15 +94,12 @@ 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

index 34e588f7c0..7a2629336d 100644 --- a/commit-reach.c +++ b/commit-reach.c @@ -79,21 +79,73 @@ static void clear_nonstale_queue(struct nonstale_queue *queue) queue->max_nonstale = NULL; } -static void nonstale_queue_put_dedup(struct nonstale_queue *queue, - struct commit *c) +/* + * 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; + int gen_ordered; +}; + +static void paint_count_update(struct paint_state *state, + unsigned flags, int delta) { - if (c->object.flags & ENQUEUED) - return; - c->object.flags |= ENQUEUED; - nonstale_queue_put(queue, c); + 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 *nonstale_queue_get_dedup(struct nonstale_queue *queue) +static struct commit *paint_queue_get(struct paint_state *state) { - struct commit *commit = nonstale_queue_get(queue); + 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; - if (commit) - commit->object.flags &= ~ENQUEUED; + paint_count_update(state, commit->object.flags, -1); return commit; } @@ -109,18 +161,19 @@ 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 }, + .gen_ordered = 1, }; + struct commit *commit; int i; - int gen_ordered = 1; 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; - gen_ordered = 0; + state.queue.compare = compare_commits_by_commit_date; + state.gen_ordered = 0; } one->object.flags |= PARENT1; @@ -128,15 +181,12 @@ static int paint_down_to_common(struct repository *r, 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); @@ -162,7 +212,7 @@ static int paint_down_to_common(struct repository *r, * descendant of this one. */ if (!(mb_flags & MERGE_BASE_FIND_ALL) && - gen_ordered && + state.gen_ordered && generation < GENERATION_NUMBER_INFINITY) break; } @@ -176,7 +226,7 @@ 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; /* @@ -191,12 +241,11 @@ 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);

index f712301a2d..e3ed69f065 100755 --- a/t/t6600-test-reach.sh +++ b/t/t6600-test-reach.sh @@ -366,7 +366,7 @@ 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' ' @@ -381,7 +381,7 @@ 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' ' @@ -438,7 +438,7 @@ test_expect_success 'merge-base --all with clock skew and redundant ancestor (si >input && git rev-parse se2-MB1 >expect && run_all_modes git merge-base --all se2-A se2-B && - test_paint_down_steps 8 7 8 8 + test_paint_down_steps 8 6 8 8 ' test_expect_success 'reduce_heads' '