1 files changed, 167 insertions, 34 deletions

diff --git a/commit-reach.c b/commit-reach.c
index dabc2972e4..a339e41aa4 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -41,8 +41,7 @@ static int compare_commits_by_gen(const void *_a, const void *_b)
 
 static int queue_has_nonstale(struct prio_queue *queue)
 {
-	int i;
-	for (i = 0; i < queue->nr; i++) {
+	for (size_t i = 0; i < queue->nr; i++) {
 		struct commit *commit = queue->array[i].data;
 		if (!(commit->object.flags & STALE))
 			return 1;
@@ -212,12 +211,13 @@ int get_octopus_merge_bases(struct commit_list *in, struct commit_list **result)
 }
 
 static int remove_redundant_no_gen(struct repository *r,
-				   struct commit **array, int cnt)
+				   struct commit **array,
+				   size_t cnt, size_t *dedup_cnt)
 {
 	struct commit **work;
 	unsigned char *redundant;
-	int *filled_index;
-	int i, j, filled;
+	size_t *filled_index;
+	size_t i, j, filled;
 
 	CALLOC_ARRAY(work, cnt);
 	redundant = xcalloc(cnt, 1);
@@ -267,20 +267,22 @@ static int remove_redundant_no_gen(struct repository *r,
 	for (i = filled = 0; i < cnt; i++)
 		if (!redundant[i])
 			array[filled++] = work[i];
+	*dedup_cnt = filled;
 	free(work);
 	free(redundant);
 	free(filled_index);
-	return filled;
+	return 0;
 }
 
 static int remove_redundant_with_gen(struct repository *r,
-				     struct commit **array, int cnt)
+				     struct commit **array, size_t cnt,
+				     size_t *dedup_cnt)
 {
-	int i, count_non_stale = 0, count_still_independent = cnt;
+	size_t i, count_non_stale = 0, count_still_independent = cnt;
 	timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 	struct commit **walk_start, **sorted;
 	size_t walk_start_nr = 0, walk_start_alloc = cnt;
-	int min_gen_pos = 0;
+	size_t min_gen_pos = 0;
 
 	/*
 	 * Sort the input by generation number, ascending. This allows
@@ -326,12 +328,12 @@ static int remove_redundant_with_gen(struct repository *r,
 	 * terminate early. Otherwise, we will do the same amount of work
 	 * as before.
 	 */
-	for (i = walk_start_nr - 1; i >= 0 && count_still_independent > 1; i--) {
+	for (i = walk_start_nr; i && count_still_independent > 1; i--) {
 		/* push the STALE bits up to min generation */
 		struct commit_list *stack = NULL;
 
-		commit_list_insert(walk_start[i], &stack);
-		walk_start[i]->object.flags |= STALE;
+		commit_list_insert(walk_start[i - 1], &stack);
+		walk_start[i - 1]->object.flags |= STALE;
 
 		while (stack) {
 			struct commit_list *parents;
@@ -388,10 +390,12 @@ static int remove_redundant_with_gen(struct repository *r,
 	clear_commit_marks_many(walk_start_nr, walk_start, STALE);
 	free(walk_start);
 
-	return count_non_stale;
+	*dedup_cnt = count_non_stale;
+	return 0;
 }
 
-static int remove_redundant(struct repository *r, struct commit **array, int cnt)
+static int remove_redundant(struct repository *r, struct commit **array,
+			    size_t cnt, size_t *dedup_cnt)
 {
 	/*
 	 * Some commit in the array may be an ancestor of
@@ -401,31 +405,30 @@ static int remove_redundant(struct repository *r, struct commit **array, int cnt
 	 * that number.
 	 */
 	if (generation_numbers_enabled(r)) {
-		int i;
-
 		/*
 		 * If we have a single commit with finite generation
 		 * number, then the _with_gen algorithm is preferred.
 		 */
-		for (i = 0; i < cnt; i++) {
+		for (size_t i = 0; i < cnt; i++) {
 			if (commit_graph_generation(array[i]) < GENERATION_NUMBER_INFINITY)
-				return remove_redundant_with_gen(r, array, cnt);
+				return remove_redundant_with_gen(r, array, cnt, dedup_cnt);
 		}
 	}
 
-	return remove_redundant_no_gen(r, array, cnt);
+	return remove_redundant_no_gen(r, array, cnt, dedup_cnt);
 }
 
 static int get_merge_bases_many_0(struct repository *r,
 				  struct commit *one,
-				  int n,
+				  size_t n,
 				  struct commit **twos,
 				  int cleanup,
 				  struct commit_list **result)
 {
 	struct commit_list *list;
 	struct commit **rslt;
-	int cnt, i;
+	size_t cnt, i;
+	int ret;
 
 	if (merge_bases_many(r, one, n, twos, result) < 0)
 		return -1;
@@ -452,8 +455,8 @@ static int get_merge_bases_many_0(struct repository *r,
 	clear_commit_marks(one, all_flags);
 	clear_commit_marks_many(n, twos, all_flags);
 
-	cnt = remove_redundant(r, rslt, cnt);
-	if (cnt < 0) {
+	ret = remove_redundant(r, rslt, cnt, &cnt);
+	if (ret < 0) {
 		free(rslt);
 		return -1;
 	}
@@ -465,7 +468,7 @@ static int get_merge_bases_many_0(struct repository *r,
 
 int repo_get_merge_bases_many(struct repository *r,
 			      struct commit *one,
-			      int n,
+			      size_t n,
 			      struct commit **twos,
 			      struct commit_list **result)
 {
@@ -474,7 +477,7 @@ int repo_get_merge_bases_many(struct repository *r,
 
 int repo_get_merge_bases_many_dirty(struct repository *r,
 				    struct commit *one,
-				    int n,
+				    size_t n,
 				    struct commit **twos,
 				    struct commit_list **result)
 {
@@ -582,7 +585,8 @@ struct commit_list *reduce_heads(struct commit_list *heads)
 	struct commit_list *p;
 	struct commit_list *result = NULL, **tail = &result;
 	struct commit **array;
-	int num_head, i;
+	size_t num_head, i;
+	int ret;
 
 	if (!heads)
 		return NULL;
@@ -603,11 +607,13 @@ struct commit_list *reduce_heads(struct commit_list *heads)
 			p->item->object.flags &= ~STALE;
 		}
 	}
-	num_head = remove_redundant(the_repository, array, num_head);
-	if (num_head < 0) {
+
+	ret = remove_redundant(the_repository, array, num_head, &num_head);
+	if (ret < 0) {
 		free(array);
 		return NULL;
 	}
+
 	for (i = 0; i < num_head; i++)
 		tail = &commit_list_insert(array[i], tail)->next;
 	free(array);
@@ -780,12 +786,12 @@ int commit_contains(struct ref_filter *filter, struct commit *commit,
 int can_all_from_reach_with_flag(struct object_array *from,
 				 unsigned int with_flag,
 				 unsigned int assign_flag,
-				 time_t min_commit_date,
+				 timestamp_t min_commit_date,
 				 timestamp_t min_generation)
 {
 	struct commit **list = NULL;
-	int i;
-	int nr_commits;
+	size_t i;
+	size_t nr_commits;
 	int result = 1;
 
 	ALLOC_ARRAY(list, from->nr);
@@ -883,9 +889,9 @@ int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 		       int cutoff_by_min_date)
 {
 	struct object_array from_objs = OBJECT_ARRAY_INIT;
-	time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
 	struct commit_list *from_iter = from, *to_iter = to;
 	int result;
+	timestamp_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
 	timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 
 	while (from_iter) {
@@ -937,8 +943,8 @@ int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 	return result;
 }
 
-struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
-					 struct commit **to, int nr_to,
+struct commit_list *get_reachable_subset(struct commit **from, size_t nr_from,
+					 struct commit **to, size_t nr_to,
 					 unsigned int reachable_flag)
 {
 	struct commit **item;
@@ -1227,4 +1233,131 @@ void tips_reachable_from_bases(struct repository *r,
 done:
 	free(commits);
 	repo_clear_commit_marks(r, SEEN);
+	free_commit_list(stack);
+}
+
+/*
+ * This slab initializes integers to zero, so use "-1" for "tip is best" and
+ * "i + 1" for "bases[i] is best".
+ */
+define_commit_slab(best_branch_base, int);
+static struct best_branch_base best_branch_base;
+#define get_best(c) (*best_branch_base_at(&best_branch_base, (c)))
+#define set_best(c,v) (*best_branch_base_at(&best_branch_base, (c)) = (v))
+
+int get_branch_base_for_tip(struct repository *r,
+			    struct commit *tip,
+			    struct commit **bases,
+			    size_t bases_nr)
+{
+	int best_index = -1;
+	struct commit *branch_point = NULL;
+	struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
+	int found_missing_gen = 0;
+
+	if (!bases_nr)
+		return -1;
+
+	repo_parse_commit(r, tip);
+	if (commit_graph_generation(tip) == GENERATION_NUMBER_INFINITY)
+		found_missing_gen = 1;
+
+	/* Check for missing generation numbers. */
+	for (size_t i = 0; i < bases_nr; i++) {
+		struct commit *c = bases[i];
+		repo_parse_commit(r, c);
+		if (commit_graph_generation(c) == GENERATION_NUMBER_INFINITY)
+			found_missing_gen = 1;
+	}
+
+	if (found_missing_gen) {
+		struct commit **commits;
+		size_t commits_nr = bases_nr + 1;
+
+		CALLOC_ARRAY(commits, commits_nr);
+		COPY_ARRAY(commits, bases, bases_nr);
+		commits[bases_nr] = tip;
+		ensure_generations_valid(r, commits, commits_nr);
+		free(commits);
+	}
+
+	/* Initialize queue and slab now that generations are guaranteed. */
+	init_best_branch_base(&best_branch_base);
+	set_best(tip, -1);
+	prio_queue_put(&queue, tip);
+
+	for (size_t i = 0; i < bases_nr; i++) {
+		struct commit *c = bases[i];
+		int best = get_best(c);
+
+		/* Has this already been marked as best by another commit? */
+		if (best) {
+			if (best == -1) {
+				/* We agree at this position. Stop now. */
+				best_index = i + 1;
+				goto cleanup;
+			}
+			continue;
+		}
+
+		set_best(c, i + 1);
+		prio_queue_put(&queue, c);
+	}
+
+	while (queue.nr) {
+		struct commit *c = prio_queue_get(&queue);
+		int best_for_c = get_best(c);
+		int best_for_p, positive;
+		struct commit *parent;
+
+		/* Have we reached a known branch point? It's optimal. */
+		if (c == branch_point)
+			break;
+
+		repo_parse_commit(r, c);
+		if (!c->parents)
+			continue;
+
+		parent = c->parents->item;
+		repo_parse_commit(r, parent);
+		best_for_p = get_best(parent);
+
+		if (!best_for_p) {
+			/* 'parent' is new, so pass along best_for_c. */
+			set_best(parent, best_for_c);
+			prio_queue_put(&queue, parent);
+			continue;
+		}
+
+		if (best_for_p > 0 && best_for_c > 0) {
+			/* Collision among bases. Minimize. */
+			if (best_for_c < best_for_p)
+				set_best(parent, best_for_c);
+			continue;
+		}
+
+		/*
+		 * At this point, we have reached a commit that is reachable
+		 * from the tip, either from 'c' or from an earlier commit to
+		 * have 'parent' as its first parent.
+		 *
+		 * Update 'best_index' to match the minimum of all base indices
+		 * to reach 'parent'.
+		 */
+
+		/* Exactly one is positive due to initial conditions. */
+		positive = (best_for_c < 0) ? best_for_p : best_for_c;
+
+		if (best_index < 0 || positive < best_index)
+			best_index = positive;
+
+		/* No matter what, track that the parent is reachable from tip. */
+		set_best(parent, -1);
+		branch_point = parent;
+	}
+
+cleanup:
+	clear_best_branch_base(&best_branch_base);
+	clear_prio_queue(&queue);
+	return best_index > 0 ? best_index - 1 : -1;
 }