upload-pack: use buffered I/O to talk to rev-list

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 rev-list by using stdio's
buffering.

Take care to handle errors immediately to get the correct error code,
and to flush the buffer explicitly before closing the stream in order to
catch any write errors for these last bytes.

Helped-by: Chris Torek <chris.torek@gmail.com>
Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/upload-pack.c b/upload-pack.c
index 951a2b23aaf8f03d08f8976557de8616bbb2b5ca..f6eb32208ee83031e8567e956eed122488560224 100644 (file)
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -595,9 +595,8 @@ static int do_reachable_revlist(struct child_process *cmd,
                "rev-list", "--stdin", NULL,
        };
        struct object *o;
-       char namebuf[GIT_MAX_HEXSZ + 2]; /* ^ + hash + LF */
+       FILE *cmd_in = NULL;
        int i;
-       const unsigned hexsz = the_hash_algo->hexsz;
 
        cmd->argv = argv;
        cmd->git_cmd = 1;
@@ -615,8 +614,8 @@ static int do_reachable_revlist(struct child_process *cmd,
        if (start_command(cmd))
                goto error;
 
-       namebuf[0] = '^';
-       namebuf[hexsz + 1] = '\n';
+       cmd_in = xfdopen(cmd->in, "w");
+
        for (i = get_max_object_index(); 0 < i; ) {
                o = get_indexed_object(--i);
                if (!o)
@@ -625,11 +624,9 @@ static int do_reachable_revlist(struct child_process *cmd,
                        o->flags &= ~TMP_MARK;
                if (!is_our_ref(o, allow_uor))
                        continue;
-               memcpy(namebuf + 1, oid_to_hex(&o->oid), hexsz);
-               if (write_in_full(cmd->in, namebuf, hexsz + 2) < 0)
+               if (fprintf(cmd_in, "^%s\n", oid_to_hex(&o->oid)) < 0)
                        goto error;
        }
-       namebuf[hexsz] = '\n';
        for (i = 0; i < src->nr; i++) {
                o = src->objects[i].item;
                if (is_our_ref(o, allow_uor)) {
@@ -639,11 +636,12 @@ static int do_reachable_revlist(struct child_process *cmd,
                }
                if (reachable && o->type == OBJ_COMMIT)
                        o->flags |= TMP_MARK;
-               memcpy(namebuf, oid_to_hex(&o->oid), hexsz);
-               if (write_in_full(cmd->in, namebuf, hexsz + 1) < 0)
+               if (fprintf(cmd_in, "%s\n", oid_to_hex(&o->oid)) < 0)
                        goto error;
        }
-       close(cmd->in);
+       if (ferror(cmd_in) || fflush(cmd_in))
+               goto error;
+       fclose(cmd_in);
        cmd->in = -1;
        sigchain_pop(SIGPIPE);
 
@@ -652,8 +650,8 @@ static int do_reachable_revlist(struct child_process *cmd,
 error:
        sigchain_pop(SIGPIPE);
 
-       if (cmd->in >= 0)
-               close(cmd->in);
+       if (cmd_in)
+               fclose(cmd_in);
        if (cmd->out >= 0)
                close(cmd->out);
        return -1;