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

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.

Helped-by: Chris Torek <chris.torek@gmail.com>
Helped-by: Johannes Sixt <j6t@kdbg.org>
Encouraged-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/midx.c b/midx.c
index 6d1584ca51d313343bbb65f9baa7c794259c7bf0..cb7da2531ab74d12b4566d44fb10c05f39e23163 100644 (file)
--- 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 +1446,9 @@ 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));
        }
-       close(cmd.in);
+       fclose(cmd_in);
 
        if (finish_command(&cmd)) {
                error(_("could not finish pack-objects"));