Merge branch 'ds/maintenance-commit-graph-auto-fix' into jch

Test-coverage enhancement of running commit-graph task "git
maintenance" as needed led to discovery and fix of a bug.

* ds/maintenance-commit-graph-auto-fix:
  maintenance: core.commitGraph=false prevents writes
  maintenance: test commit-graph auto condition

builtin/gc.c

@@ -739,9 +739,15 @@ static int dfs_on_ref(const char *refname,
 	commit = lookup_commit(the_repository, oid);
 	if (!commit)
 		return 0;
-	if (parse_commit(commit))
+	if (parse_commit(commit) ||
+	    commit_graph_position(commit) != COMMIT_NOT_FROM_GRAPH)
 		return 0;
 
+	data->num_not_in_graph++;
+
+	if (data->num_not_in_graph >= data->limit)
+		return 1;
+
 	commit_list_append(commit, &stack);
 
 	while (!result && stack) {
@@ -809,6 +815,10 @@ static int run_write_commit_graph(struct maintenance_run_opts *opts)
 
 static int maintenance_task_commit_graph(struct maintenance_run_opts *opts)
 {
+	prepare_repo_settings(the_repository);
+	if (!the_repository->settings.core_commit_graph)
+		return 0;
+
 	close_object_store(the_repository->objects);
 	if (run_write_commit_graph(opts)) {
 		error(_("failed to write commit-graph"));

t/t7900-maintenance.sh

@@ -53,6 +53,43 @@ test_expect_success 'run --task=<task>' '
 	test_subcommand git commit-graph write --split --reachable --no-progress <run-both.txt
 '
 
+test_expect_success 'core.commitGraph=false prevents write process' '
+	GIT_TRACE2_EVENT="$(pwd)/no-commit-graph.txt" \
+		git -c core.commitGraph=false maintenance run \
+		--task=commit-graph 2>/dev/null &&
+	test_subcommand ! git commit-graph write --split --reachable --no-progress \
+		<no-commit-graph.txt
+'
+
+test_expect_success 'commit-graph auto condition' '
+	COMMAND="maintenance run --task=commit-graph --auto --quiet" &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-no.txt" \
+		git -c maintenance.commit-graph.auto=1 $COMMAND &&
+	GIT_TRACE2_EVENT="$(pwd)/cg-negative-means-yes.txt" \
+		git -c maintenance.commit-graph.auto="-1" $COMMAND &&
+
+	test_commit first &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-zero-means-no.txt" \
+		git -c maintenance.commit-graph.auto=0 $COMMAND &&
+	GIT_TRACE2_EVENT="$(pwd)/cg-one-satisfied.txt" \
+		git -c maintenance.commit-graph.auto=1 $COMMAND &&
+
+	git commit --allow-empty -m "second" &&
+	git commit --allow-empty -m "third" &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-two-satisfied.txt" \
+		git -c maintenance.commit-graph.auto=2 $COMMAND &&
+
+	COMMIT_GRAPH_WRITE="git commit-graph write --split --reachable --no-progress" &&
+	test_subcommand ! $COMMIT_GRAPH_WRITE <cg-no.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-negative-means-yes.txt &&
+	test_subcommand ! $COMMIT_GRAPH_WRITE <cg-zero-means-no.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-one-satisfied.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-two-satisfied.txt
+'
+
 test_expect_success 'run --task=bogus' '
 	test_must_fail git maintenance run --task=bogus 2>err &&
 	test_i18ngrep "is not a valid task" err