commit-graph: read only from specific pack-indexes

Teach git-commit-graph to inspect the objects only in a certain list
of pack-indexes within the given pack directory. This allows updating
the commit graph iteratively.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 30 insertions, 3 deletions

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index efd39331d7..5c70199003 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -8,7 +8,7 @@
 static char const * const builtin_commit_graph_usage[] = {
 	N_("git commit-graph [--object-dir <objdir>]"),
 	N_("git commit-graph read [--object-dir <objdir>]"),
-	N_("git commit-graph write [--object-dir <objdir>]"),
+	N_("git commit-graph write [--object-dir <objdir>] [--stdin-packs]"),
 	NULL
 };
 
@@ -18,12 +18,13 @@ static const char * const builtin_commit_graph_read_usage[] = {
 };
 
 static const char * const builtin_commit_graph_write_usage[] = {
-	N_("git commit-graph write [--object-dir <objdir>]"),
+	N_("git commit-graph write [--object-dir <objdir>] [--stdin-packs]"),
 	NULL
 };
 
 static struct opts_commit_graph {
 	const char *obj_dir;
+	int stdin_packs;
 } opts;
 
 static int graph_read(int argc, const char **argv)
@@ -76,10 +77,18 @@ static int graph_read(int argc, const char **argv)
 
 static int graph_write(int argc, const char **argv)
 {
+	const char **pack_indexes = NULL;
+	int packs_nr = 0;
+	const char **lines = NULL;
+	int lines_nr = 0;
+	int lines_alloc = 0;
+
 	static struct option builtin_commit_graph_write_options[] = {
 		OPT_STRING(0, "object-dir", &opts.obj_dir,
 			N_("dir"),
 			N_("The object directory to store the graph")),
+		OPT_BOOL(0, "stdin-packs", &opts.stdin_packs,
+			N_("scan pack-indexes listed by stdin for commits")),
 		OPT_END(),
 	};
 
@@ -90,7 +99,25 @@ static int graph_write(int argc, const char **argv)
 	if (!opts.obj_dir)
 		opts.obj_dir = get_object_directory();
 
-	write_commit_graph(opts.obj_dir);
+	if (opts.stdin_packs) {
+		struct strbuf buf = STRBUF_INIT;
+		lines_nr = 0;
+		lines_alloc = 128;
+		ALLOC_ARRAY(lines, lines_alloc);
+
+		while (strbuf_getline(&buf, stdin) != EOF) {
+			ALLOC_GROW(lines, lines_nr + 1, lines_alloc);
+			lines[lines_nr++] = strbuf_detach(&buf, NULL);
+		}
+
+		pack_indexes = lines;
+		packs_nr = lines_nr;
+	}
+
+	write_commit_graph(opts.obj_dir,
+			   pack_indexes,
+			   packs_nr);
+
 	return 0;
 }