On Tue, Feb 7, 2012 at 11:50 AM, Nguyen Thai Ngoc Duy <pclouds@xxxxxxxxx> wrote:
>> Version 3 was a mistake because of the variable length record sizes.
>> Saving 2 bytes on some records that don't use the extended flags makes
>> the index file *MUCH* harder to parse. So much so that we should take
>> version 3 and kill it, not encourage it as the default!
>
> Probably too late for that, but it's good to know there are strong
> user base for v2.
OK probably not too late. We cannot kill it, but we could deprecate
it. We can introduce a mandatory extension to store extra flags. The
extension is basically an array of
struct ce_extended_flags {
int ce_index; /* points to istate->cache[ce_index] */
unsigned long flags;
};
On reading the extension, extra flags is applied back in mem, the
extension is created again when new index is written. There are only
two users of index v3: skip-worktree and intent-to-add bits, which are
not used often, I think. Still want to kill it?
Switching from sha-1 to crc32 could be done the same way (i.e. new
mandatory extension _at the end_ that contains crc32 checksum and skip
sha-1 check on reading if it's all zero) if we agree to move to crc32.
--
Duy
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