git-annex/Backend/Variety.hs
Joey Hess e7652b0997
implement URL to VURL migration
This needs the content to be present in order to hash it. But it's not
possible for a module used by Backend.URL to call inAnnex because that
would entail a dependency loop. So instead, rely on the fact that
Command.Migrate calls inAnnex before performing a migration.

But, Command.ExamineKey calls fastMigrate and the key may or may not
exist, and it's not wanting to actually perform a migration in any case.
To handle that, had to add an additional value to fastMigrate to
indicate whether the content is inAnnex.

Factored generateEquivilantKey out of Remote.Web.

Note that migrateFromURLToVURL hardcodes use of the SHA256E backend.
It would have been difficult not to, given all the dependency loop
issues. But --backend and annex.backend are used to tell git-annex
migrate to use VURL in any case, so there's no config knob that
the user could expect to configure that.

Sponsored-by: Brock Spratlen on Patreon
2024-03-01 16:42:02 -04:00

39 lines
1.1 KiB
Haskell

{- git-annex backend varieties
-
- Copyright 2012-2024 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Backend.Variety where
import qualified Data.Map as M
import Annex.Common
import Types.Key
import Types.Backend
import qualified Backend.External
-- When adding a new backend, import it here and add it to the builtinList.
import qualified Backend.Hash
import qualified Backend.WORM
import qualified Backend.URL
{- Regular backends. Does not include externals or VURL. -}
regularBackendList :: [Backend]
regularBackendList = Backend.Hash.backends
++ Backend.WORM.backends
++ Backend.URL.backends
{- The default hashing backend. -}
defaultHashBackend :: Backend
defaultHashBackend = Prelude.head regularBackendList
makeVarietyMap :: [Backend] -> M.Map KeyVariety Backend
makeVarietyMap l = M.fromList $ zip (map backendVariety l) l
maybeLookupBackendVarietyMap :: KeyVariety -> M.Map KeyVariety Backend -> Annex (Maybe Backend)
maybeLookupBackendVarietyMap (ExternalKey s hasext) _varitymap =
Just <$> Backend.External.makeBackend s hasext
maybeLookupBackendVarietyMap v varietymap =
pure $ M.lookup v varietymap