[PATCH v2 2/5] repack: populate extension bits incrementally

From: Jeff King <peff@peff.net>
Date: Oct 22, 2022, 00:21 UTC
Message-ID: <Y1M3nMNTOGAH0L82@coredump.intra.peff.net>
In-Reply-To: <Y1M3fVnixJHvKiSg@coredump.intra.peff.net>

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 <peff@peff.net>
---
 builtin/repack.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/builtin/repack.c b/builtin/repack.c
index 8e71230bf7..b5bd9e5fed 100644
--- a/builtin/repack.c
+++ b/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);
 
 	/*

-- 
2.38.1.496.ga614b0e9bd