[PATCH 4/6] commit-graph: consolidate compare_commits_by_gen

["Abhishek Kumar via GitGitGadget" <gitgitgadget@gmail.com>]

From: Abhishek Kumar <abhishekkumar8222@gmail.com>

Comparing commits by generation has been independently defined twice, in
commit-reach and commit. Let's simplify the implementation by moving
compare_commits_by_gen() to commit-graph.

Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
---
 commit-graph.c | 15 +++++++++++++++
 commit-graph.h |  2 ++
 commit-reach.c | 15 ---------------
 commit.c       |  9 +++------
 4 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/commit-graph.c b/commit-graph.c
index 204eb454b2..1c98f38d69 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -112,6 +112,21 @@ uint32_t commit_graph_generation(const struct commit *c)
 	return data->generation;
 }
 
+int compare_commits_by_gen(const void *_a, const void *_b)
+{
+	const struct commit *a = _a, *b = _b;
+	const uint32_t generation_a = commit_graph_generation(a);
+	const uint32_t generation_b = commit_graph_generation(b);
+
+	/* older commits first */
+	if (generation_a < generation_b)
+		return -1;
+	else if (generation_a > generation_b)
+		return 1;
+
+	return 0;
+}
+
 static struct commit_graph_data *commit_graph_data_at(const struct commit *c)
 {
 	unsigned int i, nth_slab;
diff --git a/commit-graph.h b/commit-graph.h
index 28f89cdf3e..98cc5a3b9d 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -145,4 +145,6 @@ struct commit_graph_data {
  */
 uint32_t commit_graph_generation(const struct commit *);
 uint32_t commit_graph_position(const struct commit *);
+
+int compare_commits_by_gen(const void *_a, const void *_b);
 #endif
diff --git a/commit-reach.c b/commit-reach.c
index efd5925cbb..c83cc291e7 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -561,21 +561,6 @@ int commit_contains(struct ref_filter *filter, struct commit *commit,
 	return repo_is_descendant_of(the_repository, commit, list);
 }
 
-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);
-
-	if (generation_a < generation_b)
-		return -1;
-	if (generation_a > generation_b)
-		return 1;
-	return 0;
-}
-
 int can_all_from_reach_with_flag(struct object_array *from,
 				 unsigned int with_flag,
 				 unsigned int assign_flag,
diff --git a/commit.c b/commit.c
index 7128895c3a..bed63b41fb 100644
--- a/commit.c
+++ b/commit.c
@@ -731,14 +731,11 @@ 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),
-		       generation_b = commit_graph_generation(b);
+	int ret_val = compare_commits_by_gen(a_, b_);
 
 	/* newer commits first */
-	if (generation_a < generation_b)
-		return 1;
-	else if (generation_a > generation_b)
-		return -1;
+	if (ret_val)
+		return -ret_val;
 
 	/* use date as a heuristic when generations are equal */
 	if (a->date < b->date)
-- 
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