[PATCH v4 09/13] commit-graph: add core.commitGraph setting

[Derrick Stolee <stolee@gmail.com>]

The commit graph feature is controlled by the new core.commitGraph config
setting. This defaults to 0, so the feature is opt-in.

The intention of core.commitGraph is that a user can always stop checking
for or parsing commit graph files if core.commitGraph=0.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/config.txt | 3 +++
 cache.h                  | 1 +
 config.c                 | 5 +++++
 environment.c            | 1 +
 4 files changed, 10 insertions(+)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 9593bfa..e90d0d1 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -883,6 +883,9 @@ core.notesRef::
 This setting defaults to "refs/notes/commits", and it can be overridden by
 the `GIT_NOTES_REF` environment variable.  See linkgit:git-notes[1].
 
+core.commitGraph::
+	Enable git commit graph feature. Allows reading from .graph files.
+
 core.sparseCheckout::
 	Enable "sparse checkout" feature. See section "Sparse checkout" in
 	linkgit:git-read-tree[1] for more information.
diff --git a/cache.h b/cache.h
index 6440e2b..1063873 100644
--- a/cache.h
+++ b/cache.h
@@ -771,6 +771,7 @@ extern char *git_replace_ref_base;
 
 extern int fsync_object_files;
 extern int core_preload_index;
+extern int core_commit_graph;
 extern int core_apply_sparse_checkout;
 extern int precomposed_unicode;
 extern int protect_hfs;
diff --git a/config.c b/config.c
index 41862d4..614cf59 100644
--- a/config.c
+++ b/config.c
@@ -1213,6 +1213,11 @@ static int git_default_core_config(const char *var, const char *value)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.commitgraph")) {
+		core_commit_graph = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp(var, "core.sparsecheckout")) {
 		core_apply_sparse_checkout = git_config_bool(var, value);
 		return 0;
diff --git a/environment.c b/environment.c
index 8289c25..81fed83 100644
--- a/environment.c
+++ b/environment.c
@@ -60,6 +60,7 @@ 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_apply_sparse_checkout;
 int merge_log_config = -1;
 int precomposed_unicode = -1; /* see probe_utf8_pathname_composition() */
-- 
2.7.4