[RFC PATCH 1/6] DO NOT MERGE: compute commit-graph on every commit

[Derrick Stolee <dstolee@microsoft.com>]

Also enable core.commitGraph and gc.commitGraph. Helps to test the
commit-graph feature with the rest of the test infrastructure.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/commit.c | 5 +++++
 builtin/gc.c     | 2 +-
 environment.c    | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index e8e8d13be4..8751b816c1 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -32,6 +32,7 @@
 #include "column.h"
 #include "sequencer.h"
 #include "mailmap.h"
+#include "commit-graph.h"
 
 static const char * const builtin_commit_usage[] = {
 	N_("git commit [<options>] [--] <pathspec>..."),
@@ -1623,5 +1624,9 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 
 	UNLEAK(err);
 	UNLEAK(sb);
+
+	if (core_commit_graph)
+		write_commit_graph_reachable(get_object_directory(), 1);
+
 	return 0;
 }
diff --git a/builtin/gc.c b/builtin/gc.c
index efd214a59f..999c09d8e2 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -35,7 +35,7 @@ static int aggressive_depth = 50;
 static int aggressive_window = 250;
 static int gc_auto_threshold = 6700;
 static int gc_auto_pack_limit = 50;
-static int gc_commit_graph = 0;
+static int gc_commit_graph = 1;
 static int detach_auto = 1;
 static timestamp_t gc_log_expire_time;
 static const char *gc_log_expire = "1.day.ago";
diff --git a/environment.c b/environment.c
index 8853e2f0dd..fdb2d56d90 100644
--- a/environment.c
+++ b/environment.c
@@ -62,7 +62,7 @@ enum push_default_type push_default = PUSH_DEFAULT_UNSPECIFIED;
 enum object_creation_mode object_creation_mode = OBJECT_CREATION_MODE;
 char *notes_ref_name;
 int grafts_replace_parents = 1;
-int core_commit_graph;
+int core_commit_graph = 1;
 int core_apply_sparse_checkout;
 int merge_log_config = -1;
 int precomposed_unicode = -1; /* see probe_utf8_pathname_composition() */
-- 
2.16.2.338.gcfe06ae955