repack: populate extension bits incrementally

After generating the main pack and then any additional cruft packs, we
iterate over the "names" list (which contains hashes of packs generated
by pack-objects), and call populate_pack_exts() for each.

There's one small problem with this. In repack_promisor_objects(), we
may add entries to "names" and call populate_pack_exts() for them.
Calling it again is mostly just wasteful, as we'll stat() the filename
with each possible extension, get the same result, and just overwrite
our bits.

So we could drop the call there, and leave the final loop to populate
all of the bits. But instead, this patch does the reverse: drops the
final loop, and teaches the other two sites to populate the bits as they
add entries.

This makes the code easier to reason about, as you never have to worry
about when the util field is valid; it is always valid for each entry.

It also serves my ulterior purpose: recording the generated filenames as
soon as possible will make it easier for a future patch to use them for
cleaning up from a failed operation.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

builtin/repack.c

@@ -714,10 +714,14 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 
 	out = xfdopen(cmd.out, "r");
 	while (strbuf_getline_lf(&line, out) != EOF) {
+		struct string_list_item *item;
+
 		if (line.len != the_hash_algo->hexsz)
 			die(_("repack: Expecting full hex object ID lines only "
 			      "from pack-objects."));
-		string_list_append(names, line.buf);
+
+		item = string_list_append(names, line.buf);
+		item->util = populate_pack_exts(line.buf);
 	}
 	fclose(out);
 
@@ -956,9 +960,12 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 
 	out = xfdopen(cmd.out, "r");
 	while (strbuf_getline_lf(&line, out) != EOF) {
+		struct string_list_item *item;
+
 		if (line.len != the_hash_algo->hexsz)
 			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
-		string_list_append(&names, line.buf);
+		item = string_list_append(&names, line.buf);
+		item->util = populate_pack_exts(item->string);
 	}
 	fclose(out);
 	ret = finish_command(&cmd);
@@ -997,10 +1004,6 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 
 	string_list_sort(&names);
 
-	for_each_string_list_item(item, &names) {
-		item->util = populate_pack_exts(item->string);
-	}
-
 	close_object_store(the_repository->objects);
 
 	/*