[PATCH] midx: use buffered I/O to talk to pack-objects

["René Scharfe" <l.s.r@web.de>]

Like f0bca72dc77 (send-pack: use buffered I/O to talk to pack-objects,
2016-06-08), significantly reduce the number of system calls and
simplify the code for sending object IDs to pack-objects by using
stdio's buffering and handling errors after the loop.

Signed-off-by: René Scharfe <l.s.r@web.de>
---
 midx.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/midx.c b/midx.c
index 6d1584ca51d..742638c3e51 100644
--- a/midx.c
+++ b/midx.c
@@ -1383,6 +1383,7 @@ int midx_repack(struct repository *r, const char *object_dir, size_t batch_size,
 	uint32_t i;
 	unsigned char *include_pack;
 	struct child_process cmd = CHILD_PROCESS_INIT;
+	FILE *cmd_in;
 	struct strbuf base_name = STRBUF_INIT;
 	struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);

@@ -1435,6 +1436,8 @@ int midx_repack(struct repository *r, const char *object_dir, size_t batch_size,
 		goto cleanup;
 	}

+	cmd_in = xfdopen(cmd.in, "w");
+
 	for (i = 0; i < m->num_objects; i++) {
 		struct object_id oid;
 		uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
@@ -1443,10 +1446,15 @@ int midx_repack(struct repository *r, const char *object_dir, size_t batch_size,
 			continue;

 		nth_midxed_object_oid(&oid, m, i);
-		xwrite(cmd.in, oid_to_hex(&oid), the_hash_algo->hexsz);
-		xwrite(cmd.in, "\n", 1);
+		fprintf(cmd_in, "%s\n", oid_to_hex(&oid));
+	}
+
+	if (fclose(cmd_in)) {
+		error_errno(_("could not close stdin of pack-objects"));
+		result = 1;
+		finish_command(&cmd);
+		goto cleanup;
 	}
-	close(cmd.in);

 	if (finish_command(&cmd)) {
 		error(_("could not finish pack-objects"));
--
2.28.0