commit-graph: return 64-bit generation number

In a preparatory step for introducing corrected commit dates, let's
return timestamp_t values from commit_graph_generation(), use
timestamp_t for local variables and define GENERATION_NUMBER_INFINITY
as (2 ^ 63 - 1) instead.

We rename GENERATION_NUMBER_MAX to GENERATION_NUMBER_V1_MAX to
represent the largest topological level we can store in the commit data
chunk.

With corrected commit dates implemented, we will have two such *_MAX
variables to denote the largest offset and largest topological level
that can be stored.

Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit-graph.c

@@ -101,7 +101,7 @@ uint32_t commit_graph_position(const struct commit *c)
 	return data ? data->graph_pos : COMMIT_NOT_FROM_GRAPH;
 }
 
-uint32_t commit_graph_generation(const struct commit *c)
+timestamp_t commit_graph_generation(const struct commit *c)
 {
 	struct commit_graph_data *data =
 		commit_graph_data_slab_peek(&commit_graph_data_slab, c);
@@ -150,8 +150,8 @@ static int commit_gen_cmp(const void *va, const void *vb)
 	const struct commit *a = *(const struct commit **)va;
 	const struct commit *b = *(const struct commit **)vb;
 
-	uint32_t generation_a = commit_graph_data_at(a)->generation;
-	uint32_t generation_b = commit_graph_data_at(b)->generation;
+	const timestamp_t generation_a = commit_graph_data_at(a)->generation;
+	const timestamp_t generation_b = commit_graph_data_at(b)->generation;
 	/* lower generation commits first */
 	if (generation_a < generation_b)
 		return -1;
@@ -1370,8 +1370,8 @@ static void compute_generation_numbers(struct write_commit_graph_context *ctx)
 			if (all_parents_computed) {
 				pop_commit(&list);
 
-				if (max_level > GENERATION_NUMBER_MAX - 1)
-					max_level = GENERATION_NUMBER_MAX - 1;
+				if (max_level > GENERATION_NUMBER_V1_MAX - 1)
+					max_level = GENERATION_NUMBER_V1_MAX - 1;
 				*topo_level_slab_at(ctx->topo_levels, current) = max_level + 1;
 			}
 		}
@@ -2367,8 +2367,8 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
 	for (i = 0; i < g->num_commits; i++) {
 		struct commit *graph_commit, *odb_commit;
 		struct commit_list *graph_parents, *odb_parents;
-		uint32_t max_generation = 0;
-		uint32_t generation;
+		timestamp_t max_generation = 0;
+		timestamp_t generation;
 
 		display_progress(progress, i + 1);
 		hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
@@ -2432,16 +2432,16 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
 			continue;
 
 		/*
-		 * If one of our parents has generation GENERATION_NUMBER_MAX, then
-		 * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
+		 * If one of our parents has generation GENERATION_NUMBER_V1_MAX, then
+		 * our generation is also GENERATION_NUMBER_V1_MAX. Decrement to avoid
 		 * extra logic in the following condition.
 		 */
-		if (max_generation == GENERATION_NUMBER_MAX)
+		if (max_generation == GENERATION_NUMBER_V1_MAX)
 			max_generation--;
 
 		generation = commit_graph_generation(graph_commit);
 		if (generation != max_generation + 1)
-			graph_report(_("commit-graph generation for commit %s is %u != %u"),
+			graph_report(_("commit-graph generation for commit %s is %"PRItime" != %"PRItime),
 				     oid_to_hex(&cur_oid),
 				     generation,
 				     max_generation + 1);

commit-graph.h

@@ -145,12 +145,12 @@ void disable_commit_graph(struct repository *r);
 
 struct commit_graph_data {
 	uint32_t graph_pos;
-	uint32_t generation;
+	timestamp_t generation;
 };
 
 /*
  * Commits should be parsed before accessing generation, graph positions.
  */
-uint32_t commit_graph_generation(const struct commit *);
+timestamp_t commit_graph_generation(const struct commit *);
 uint32_t commit_graph_position(const struct commit *);
 #endif

commit-reach.c

@@ -32,12 +32,12 @@ static int queue_has_nonstale(struct prio_queue *queue)
 static struct commit_list *paint_down_to_common(struct repository *r,
 						struct commit *one, int n,
 						struct commit **twos,
-						int min_generation)
+						timestamp_t min_generation)
 {
 	struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 	struct commit_list *result = NULL;
 	int i;
-	uint32_t last_gen = GENERATION_NUMBER_INFINITY;
+	timestamp_t last_gen = GENERATION_NUMBER_INFINITY;
 
 	if (!min_generation)
 		queue.compare = compare_commits_by_commit_date;
@@ -58,10 +58,10 @@ static struct commit_list *paint_down_to_common(struct repository *r,
 		struct commit *commit = prio_queue_get(&queue);
 		struct commit_list *parents;
 		int flags;
-		uint32_t generation = commit_graph_generation(commit);
+		timestamp_t generation = commit_graph_generation(commit);
 
 		if (min_generation && generation > last_gen)
-			BUG("bad generation skip %8x > %8x at %s",
+			BUG("bad generation skip %"PRItime" > %"PRItime" at %s",
 			    generation, last_gen,
 			    oid_to_hex(&commit->object.oid));
 		last_gen = generation;
@@ -177,12 +177,12 @@ static int remove_redundant(struct repository *r, struct commit **array, int cnt
 		repo_parse_commit(r, array[i]);
 	for (i = 0; i < cnt; i++) {
 		struct commit_list *common;
-		uint32_t min_generation = commit_graph_generation(array[i]);
+		timestamp_t min_generation = commit_graph_generation(array[i]);
 
 		if (redundant[i])
 			continue;
 		for (j = filled = 0; j < cnt; j++) {
-			uint32_t curr_generation;
+			timestamp_t curr_generation;
 			if (i == j || redundant[j])
 				continue;
 			filled_index[filled] = j;
@@ -321,7 +321,7 @@ int repo_in_merge_bases_many(struct repository *r, struct commit *commit,
 {
 	struct commit_list *bases;
 	int ret = 0, i;
-	uint32_t generation, max_generation = GENERATION_NUMBER_ZERO;
+	timestamp_t generation, max_generation = GENERATION_NUMBER_ZERO;
 
 	if (repo_parse_commit(r, commit))
 		return ret;
@@ -470,7 +470,7 @@ static int in_commit_list(const struct commit_list *want, struct commit *c)
 static enum contains_result contains_test(struct commit *candidate,
 					  const struct commit_list *want,
 					  struct contains_cache *cache,
-					  uint32_t cutoff)
+					  timestamp_t cutoff)
 {
 	enum contains_result *cached = contains_cache_at(cache, candidate);
 
@@ -506,11 +506,11 @@ static enum contains_result contains_tag_algo(struct commit *candidate,
 {
 	struct contains_stack contains_stack = { 0, 0, NULL };
 	enum contains_result result;
-	uint32_t cutoff = GENERATION_NUMBER_INFINITY;
+	timestamp_t cutoff = GENERATION_NUMBER_INFINITY;
 	const struct commit_list *p;
 
 	for (p = want; p; p = p->next) {
-		uint32_t generation;
+		timestamp_t generation;
 		struct commit *c = p->item;
 		load_commit_graph_info(the_repository, c);
 		generation = commit_graph_generation(c);
@@ -566,8 +566,8 @@ static int compare_commits_by_gen(const void *_a, const void *_b)
 	const struct commit *a = *(const struct commit * const *)_a;
 	const struct commit *b = *(const struct commit * const *)_b;
 
-	uint32_t generation_a = commit_graph_generation(a);
-	uint32_t generation_b = commit_graph_generation(b);
+	timestamp_t generation_a = commit_graph_generation(a);
+	timestamp_t generation_b = commit_graph_generation(b);
 
 	if (generation_a < generation_b)
 		return -1;
@@ -580,7 +580,7 @@ int can_all_from_reach_with_flag(struct object_array *from,
 				 unsigned int with_flag,
 				 unsigned int assign_flag,
 				 time_t min_commit_date,
-				 uint32_t min_generation)
+				 timestamp_t min_generation)
 {
 	struct commit **list = NULL;
 	int i;
@@ -681,13 +681,13 @@ int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 	time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
 	struct commit_list *from_iter = from, *to_iter = to;
 	int result;
-	uint32_t min_generation = GENERATION_NUMBER_INFINITY;
+	timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 
 	while (from_iter) {
 		add_object_array(&from_iter->item->object, NULL, &from_objs);
 
 		if (!parse_commit(from_iter->item)) {
-			uint32_t generation;
+			timestamp_t generation;
 			if (from_iter->item->date < min_commit_date)
 				min_commit_date = from_iter->item->date;
 
@@ -701,7 +701,7 @@ int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 
 	while (to_iter) {
 		if (!parse_commit(to_iter->item)) {
-			uint32_t generation;
+			timestamp_t generation;
 			if (to_iter->item->date < min_commit_date)
 				min_commit_date = to_iter->item->date;
 
@@ -741,13 +741,13 @@ struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
 	struct commit_list *found_commits = NULL;
 	struct commit **to_last = to + nr_to;
 	struct commit **from_last = from + nr_from;
-	uint32_t min_generation = GENERATION_NUMBER_INFINITY;
+	timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 	int num_to_find = 0;
 
 	struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 
 	for (item = to; item < to_last; item++) {
-		uint32_t generation;
+		timestamp_t generation;
 		struct commit *c = *item;
 
 		parse_commit(c);

commit-reach.h

@@ -87,7 +87,7 @@ int can_all_from_reach_with_flag(struct object_array *from,
 				 unsigned int with_flag,
 				 unsigned int assign_flag,
 				 time_t min_commit_date,
-				 uint32_t min_generation);
+				 timestamp_t min_generation);
 int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 		       int commit_date_cutoff);
 

commit.c

@@ -731,7 +731,7 @@ int compare_commits_by_author_date(const void *a_, const void *b_,
 int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused)
 {
 	const struct commit *a = a_, *b = b_;
-	const uint32_t generation_a = commit_graph_generation(a),
+	const timestamp_t generation_a = commit_graph_generation(a),
 			  generation_b = commit_graph_generation(b);
 
 	/* newer commits first */

commit.h

@@ -11,8 +11,8 @@
 #include "commit-slab.h"
 
 #define COMMIT_NOT_FROM_GRAPH 0xFFFFFFFF
-#define GENERATION_NUMBER_INFINITY 0xFFFFFFFF
-#define GENERATION_NUMBER_MAX 0x3FFFFFFF
+#define GENERATION_NUMBER_INFINITY ((1ULL << 63) - 1)
+#define GENERATION_NUMBER_V1_MAX 0x3FFFFFFF
 #define GENERATION_NUMBER_ZERO 0
 
 struct commit_list {

revision.c

@@ -3300,7 +3300,7 @@ define_commit_slab(indegree_slab, int);
 define_commit_slab(author_date_slab, timestamp_t);
 
 struct topo_walk_info {
-	uint32_t min_generation;
+	timestamp_t min_generation;
 	struct prio_queue explore_queue;
 	struct prio_queue indegree_queue;
 	struct prio_queue topo_queue;
@@ -3346,7 +3346,7 @@ static void explore_walk_step(struct rev_info *revs)
 }
 
 static void explore_to_depth(struct rev_info *revs,
-			     uint32_t gen_cutoff)
+			     timestamp_t gen_cutoff)
 {
 	struct topo_walk_info *info = revs->topo_walk_info;
 	struct commit *c;
@@ -3389,7 +3389,7 @@ static void indegree_walk_step(struct rev_info *revs)
 }
 
 static void compute_indegrees_to_depth(struct rev_info *revs,
-				       uint32_t gen_cutoff)
+				       timestamp_t gen_cutoff)
 {
 	struct topo_walk_info *info = revs->topo_walk_info;
 	struct commit *c;
@@ -3447,7 +3447,7 @@ static void init_topo_walk(struct rev_info *revs)
 	info->min_generation = GENERATION_NUMBER_INFINITY;
 	for (list = revs->commits; list; list = list->next) {
 		struct commit *c = list->item;
-		uint32_t generation;
+		timestamp_t generation;
 
 		if (repo_parse_commit_gently(revs->repo, c, 1))
 			continue;
@@ -3508,7 +3508,7 @@ static void expand_topo_walk(struct rev_info *revs, struct commit *commit)
 	for (p = commit->parents; p; p = p->next) {
 		struct commit *parent = p->item;
 		int *pi;
-		uint32_t generation;
+		timestamp_t generation;
 
 		if (parent->object.flags & UNINTERESTING)
 			continue;

upload-pack.c

@@ -500,7 +500,7 @@ static int got_oid(struct upload_pack_data *data,
 
 static int ok_to_give_up(struct upload_pack_data *data)
 {
-	uint32_t min_generation = GENERATION_NUMBER_ZERO;
+	timestamp_t min_generation = GENERATION_NUMBER_ZERO;
 
 	if (!data->have_obj.nr)
 		return 0;