This commit is contained in:
Joey Hess 2010-10-10 15:04:18 -04:00
parent f4d2a05e86
commit cc23519235
6 changed files with 79 additions and 30 deletions

View file

@ -18,24 +18,60 @@
module Backend where
import GitRepo
import System.Directory
import GitRepo
import Utility
type Key = String
data Backend = Backend {
name :: String, -- name of this backend
keyvalue :: FilePath -> Maybe String, -- maps from key to value
retrievekey :: IO String -> IO (Bool) -- retrieves value given key
-- name of this backend
name :: String,
-- converts a filename to a key
getKey :: FilePath -> IO (Maybe Key),
-- stores a file's contents to a key
storeFileKey :: FilePath -> Key -> IO (Bool),
-- retrieves a key's contents to a file
retrieveKeyFile :: IO Key -> FilePath -> IO (Bool)
}
instance Show Backend where
show backend = "Backend { name =\"" ++ (name backend) ++ "\" }"
{- Name of state file that holds the key for an annexed file,
- using a given backend. -}
backendFile :: Backend -> GitRepo -> FilePath -> String
backendFile backend repo file = gitStateDir repo ++
(gitRelative repo file) ++ "." ++ (name backend)
{- Attempts to Stores a file in one of the backends. -}
storeFile :: [Backend] -> GitRepo -> FilePath -> IO (Bool)
storeFile [] _ _ = return False
storeFile (b:bs) repo file = do
try <- (getKey b) (gitRelative repo file)
case (try) of
Nothing -> storeFile bs repo file
Just key -> do
(storeFileKey b) file key
createDirectoryIfMissing True (parentDir backendfile)
writeFile backendfile key
return True
where backendfile = backendFile b repo file
{- Attempts to retrieve an file from one of the backends, saving it to
- a specified location. -}
retrieveFile :: [Backend] -> GitRepo -> FilePath -> FilePath -> IO (Bool)
retrieveFile backends repo file dest = do
result <- lookupBackend backends repo file
case (result) of
Nothing -> return False
Just b -> (retrieveKeyFile b) key dest
where
key = readFile (backendFile b repo file)
{- Looks up the backend used for an already annexed file. -}
lookupBackend :: [Backend] -> GitRepo -> FilePath -> IO (Maybe Backend)
lookupBackend [] repo file = return Nothing
lookupBackend [] _ _ = return Nothing
lookupBackend (b:bs) repo file = do
present <- checkBackend b repo file
if present
@ -47,12 +83,3 @@ lookupBackend (b:bs) repo file = do
{- Checks if a file is available via a given backend. -}
checkBackend :: Backend -> GitRepo -> FilePath -> IO (Bool)
checkBackend backend repo file = doesFileExist $ backendFile backend repo file
{- Attempts to retrieve an annexed file from one of the backends. -}
retrieveFile :: [Backend] -> GitRepo -> FilePath -> IO (Bool)
retrieveFile backends repo file = do
result <- lookupBackend backends repo file
case (result) of
Nothing -> return False
Just b -> (retrievekey b) key
where key = readFile (backendFile b repo file)