Re: [PATCH v3 15/16] pack-revindex: write multi-pack reverse indexes

On Thu, Mar 11, 2021 at 12:05:38PM -0500, Taylor Blau wrote:

Implement the writing half of multi-pack reverse indexes. This is
nothing more than the format describe a few patches ago, with a new set
of helper functions that will be used to clear out stale .rev files
corresponding to old MIDXs.

Looks good.

+struct clear_midx_data {
+	char *keep;
+	const char *ext;
+};
+
+static void clear_midx_file_ext(const char *full_path, size_t full_path_len,
+				const char *file_name, void *_data)

This will clean up _any_ stale midx .rev file. So even if we miss one
when writing a new midx (due to a bug, race, power loss, etc), we'll
catch it later.

We _might_ want to also teach various tempfile-cleanup code run by gc to
likewise look for unattached midx .rev files, but I don't think we
necessarily have to do it now.

The sole caller now doesn't pass the "keep" hash, so we'd always delete
all of them. I guess we'll see that change once somebody starts actually
writing them.

-Peff