Re: [PATCH 4/8] midx: track whether we have loaded the MIDX

On 25/07/09 09:54AM, Patrick Steinhardt wrote:

When calling `prepare_multi_pack_index_one()` we know to skip loading a
multi-pack index that we have already loaded beforehand. While this
works well in case there actually is a multi-pack index, it doesn't work
when we already tried to load a nonexistent one.

This doesn't cause problems with the current layout, where users
typically iterate through MIDXs via the linked list stored in the object
database. But that linked list is going away, and those users will
instead have to call `get_multi_pack_index()` for each object source. So
if one of those sources doesn't have an MIDX, we may end up trying to
repeatedly load it even though we know it doesn't exist.

IIUC, in its current form `get_multi_pack_index()` returns the global
list of MIDXs. The MIDXs are loaded when calling `prepare_packed_git()`
into both the global `r->objects->multi_pack_index` and
`source->multi_pack_index` for each source as appropriate.

Looking at `prepare_packed_git()`, it checks
`r->objects->packed_git_initialized` to see if it has already been
initialized. If the intent is to start calling `get_multi_pack_index()`
for each source individually, doesn't `prepare_packed_git()` still only
execute once regardless already?

Address this issue by introducing a new variable that tracks whether we
have tried to load multi-pack index of a given source.

The contents of the patch look good, but I'm not entirely sure
introducing a separate variable to track if the source has attempted to
load a MIDX is useful.

-Justin