Use generation numbers for --topo-order

2.19.1.542.gc4df23f792

-->8--

1:  2358cfd5ed = 1:  7c75a56505 prio-queue: add 'peek' operation
2:  3a4b68e479 = 2:  686c4370de test-reach: add run_three_modes method
3:  12a3f6d367 = 3:  7410c00982 test-reach: add rev-list tests
4:  cd9eef9688 = 4:  5439e11e37 revision.c: begin refactoring --topo-order logic
5:  f3e291665d ! 5:  71554deb9b commit/revisions: bookkeeping before refactoring
    @@ -9,8 +9,8 @@
            compare_commits_by_author_date() in revision.c. These are used
            currently by sort_in_topological_order() in commit.c.
     
    -    2. Moving these methods to commit.h requires adding the author_slab
    -       definition to commit.h.
    +    2. Moving these methods to commit.h requires adding an author_date_slab
    +       declaration to commit.h. Consumers will need their own implementation.
     
         3. The add_parents_to_list() method in revision.c performs logic
            around the UNINTERESTING flag and other special cases depending
    @@ -31,8 +31,7 @@
      define_commit_slab(indegree_slab, int);
      
     -/* record author-date for each commit object */
    --define_commit_slab(author_date_slab, timestamp_t);
    -+implement_shared_commit_slab(author_date_slab, timestamp_t);
    + define_commit_slab(author_date_slab, timestamp_t);
      
     -static void record_author_date(struct author_date_slab *author_date,
     -			       struct commit *commit)
    @@ -69,8 +68,7 @@
      extern int check_commit_signature(const struct commit *commit, struct signature_check *sigc);
      
     +/* record author-date for each commit object */
    -+define_shared_commit_slab(author_date_slab, timestamp_t);
    -+
    ++struct author_date_slab;
     +void record_author_date(struct author_date_slab *author_date,
     +			struct commit *commit);
     +
6:  aa0bb2221d ! 6:  84c142e0bc revision.c: generation-based topo-order algorithm
    @@ -195,6 +195,7 @@
      
     -struct topo_walk_info {};
     +define_commit_slab(indegree_slab, int);
    ++define_commit_slab(author_date_slab, timestamp_t);
     +
     +struct topo_walk_info {
     +	uint32_t min_generation;
    @@ -243,12 +244,12 @@
     +}
     +
     +static void explore_to_depth(struct rev_info *revs,
    -+			     uint32_t gen)
    ++			     uint32_t gen_cutoff)
     +{
     +	struct topo_walk_info *info = revs->topo_walk_info;
     +	struct commit *c;
     +	while ((c = prio_queue_peek(&info->explore_queue)) &&
    -+	       c->generation >= gen)
    ++	       c->generation >= gen_cutoff)
     +		explore_walk_step(revs);
     +}
     +
    @@ -266,9 +267,6 @@
     +
     +	explore_to_depth(revs, c->generation);
     +
    -+	if (parse_commit_gently(c, 1) < 0)
    -+		return;
    -+
     +	for (p = c->parents; p; p = p->next) {
     +		struct commit *parent = p->item;
     +		int *pi = indegree_slab_at(&info->indegree, parent);
    @@ -285,12 +283,13 @@
     +	}
     +}
     +
    -+static void compute_indegrees_to_depth(struct rev_info *revs)
    ++static void compute_indegrees_to_depth(struct rev_info *revs,
    ++				       uint32_t gen_cutoff)
     +{
     +	struct topo_walk_info *info = revs->topo_walk_info;
     +	struct commit *c;
     +	while ((c = prio_queue_peek(&info->indegree_queue)) &&
    -+	       c->generation >= info->min_generation)
    ++	       c->generation >= gen_cutoff)
     +		indegree_walk_step(revs);
     +}
      
    @@ -305,9 +304,9 @@
     -	limit_list(revs);
     -	sort_in_topological_order(&revs->commits, revs->sort_order);
     +	init_indegree_slab(&info->indegree);
    -+	memset(&info->explore_queue, '\0', sizeof(info->explore_queue));
    -+	memset(&info->indegree_queue, '\0', sizeof(info->indegree_queue));
    -+	memset(&info->topo_queue, '\0', sizeof(info->topo_queue));
    ++	memset(&info->explore_queue, 0, sizeof(info->explore_queue));
    ++	memset(&info->indegree_queue, 0, sizeof(info->indegree_queue));
    ++	memset(&info->topo_queue, 0, sizeof(info->topo_queue));
     +
     +	switch (revs->sort_order) {
     +	default: /* REV_SORT_IN_GRAPH_ORDER */
    @@ -329,23 +328,22 @@
     +	info->min_generation = GENERATION_NUMBER_INFINITY;
     +	for (list = revs->commits; list; list = list->next) {
     +		struct commit *c = list->item;
    -+		test_flag_and_insert(&info->explore_queue, c, TOPO_WALK_EXPLORED);
    -+		test_flag_and_insert(&info->indegree_queue, c, TOPO_WALK_INDEGREE);
     +
     +		if (parse_commit_gently(c, 1))
     +			continue;
    ++
    ++		test_flag_and_insert(&info->explore_queue, c, TOPO_WALK_EXPLORED);
    ++		test_flag_and_insert(&info->indegree_queue, c, TOPO_WALK_INDEGREE);
    ++
     +		if (c->generation < info->min_generation)
     +			info->min_generation = c->generation;
    -+	}
     +
    -+	for (list = revs->commits; list; list = list->next) {
    -+		struct commit *c = list->item;
     +		*(indegree_slab_at(&info->indegree, c)) = 1;
     +
     +		if (revs->sort_order == REV_SORT_BY_AUTHOR_DATE)
     +			record_author_date(&info->author_date, c);
     +	}
    -+	compute_indegrees_to_depth(revs);
    ++	compute_indegrees_to_depth(revs, info->min_generation);
     +
     +	for (list = revs->commits; list; list = list->next) {
     +		struct commit *c = list->item;
    @@ -385,9 +383,8 @@
     +	if (process_parents(revs, commit, NULL, NULL) < 0) {
      		if (!revs->ignore_missing_links)
      			die("Failed to traverse parents of commit %s",
    --			    oid_to_hex(&commit->object.oid));
    -+				oid_to_hex(&commit->object.oid));
    -+	}
    + 			    oid_to_hex(&commit->object.oid));
    + 	}
     +
     +	for (p = commit->parents; p; p = p->next) {
     +		struct commit *parent = p->item;
    @@ -398,7 +395,7 @@
     +
     +		if (parent->generation < info->min_generation) {
     +			info->min_generation = parent->generation;
    -+			compute_indegrees_to_depth(revs);
    ++			compute_indegrees_to_depth(revs, info->min_generation);
     +		}
     +
     +		pi = indegree_slab_at(&info->indegree, parent);
    @@ -409,9 +406,10 @@
     +
     +		if (revs->first_parent_only)
     +			return;
    - 	}
    ++	}
      }
      
    + int prepare_revision_walk(struct rev_info *revs)
     
      diff --git a/revision.h b/revision.h
      --- a/revision.h
7:  a21febe112 = 7:  5479087812 t6012: make rev-list tests more interesting