git-annex/Remote/Ddar.hs
Joey Hess 8025decc7f run Preparer to get Remover and CheckPresent actions
This will allow special remotes to eg, open a http connection and reuse it,
while checking if chunks are present, or removing chunks.

S3 and WebDAV both need this to support chunks with reasonable speed.

Note that a special remote might want to cache a http connection across
multiple requests. A simple case of this is that CheckPresent is typically
called before Store or Remove. A remote using this interface can certianly
use a Preparer that eg, uses a MVar to cache a http connection.

However, it's up to the remote to then deal with things like stale or
stalled http connections when eg, doing a series of downloads from a remote
and other places. There could be long delays between calls to a remote,
which could lead to eg, http connection stalls; the machine might even
move to a new network, etc.

It might be nice to improve this interface later to allow
the simple case without needing to handle the full complex case.
One way to do it would be to have a `Transaction SpecialRemote cache`,
where SpecialRemote contains methods for Storer, Retriever, Remover, and
CheckPresent, that all expect to be passed a `cache`.
2014-08-06 14:28:36 -04:00

196 lines
5.9 KiB
Haskell

{- Using ddar as a remote. Based on bup and rsync remotes.
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
- Copyright 2014 Robie Basak <robie@justgohome.co.uk>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Remote.Ddar (remote) where
import Control.Exception
import qualified Data.Map as M
import qualified Data.ByteString.Lazy as L
import System.IO.Error
import Data.String.Utils
import Common.Annex
import Types.Remote
import Types.Key
import Types.Creds
import qualified Git
import Config
import Config.Cost
import Remote.Helper.Special
import Annex.Ssh
import Annex.UUID
type DdarRepo = String
remote :: RemoteType
remote = RemoteType {
typename = "ddar",
enumerate = findSpecialRemotes "ddarrepo",
generate = gen,
setup = ddarSetup
}
gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
gen r u c gc = do
cst <- remoteCost gc $
if ddarLocal ddarrepo
then nearlyCheapRemoteCost
else expensiveRemoteCost
return $ Just $ specialRemote' specialcfg c
(simplyPrepare $ store ddarrepo)
(simplyPrepare $ retrieve ddarrepo)
(simplyPrepare $ remove ddarrepo)
(simplyPrepare $ checkKey ddarrepo)
(this cst)
where
this cst = Remote
{ uuid = u
, cost = cst
, name = Git.repoDescribe r
, storeKey = storeKeyDummy
, retrieveKeyFile = retreiveKeyFileDummy
, retrieveKeyFileCheap = retrieveCheap
, removeKey = removeKeyDummy
, checkPresent = checkPresentDummy
, checkPresentCheap = ddarLocal ddarrepo
, whereisKey = Nothing
, remoteFsck = Nothing
, repairRepo = Nothing
, config = c
, repo = r
, gitconfig = gc
, localpath = if ddarLocal ddarrepo && not (null ddarrepo)
then Just ddarrepo
else Nothing
, remotetype = remote
, availability = if ddarLocal ddarrepo then LocallyAvailable else GloballyAvailable
, readonly = False
}
ddarrepo = fromMaybe (error "missing ddarrepo") $ remoteAnnexDdarRepo gc
specialcfg = (specialRemoteCfg c)
-- chunking would not improve ddar
{ chunkConfig = NoChunks
}
ddarSetup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
ddarSetup mu _ c = do
u <- maybe (liftIO genUUID) return mu
-- verify configuration is sane
let ddarrepo = fromMaybe (error "Specify ddarrepo=") $
M.lookup "ddarrepo" c
c' <- encryptionSetup c
-- The ddarrepo is stored in git config, as well as this repo's
-- persistant state, so it can vary between hosts.
gitConfigSpecialRemote u c' "ddarrepo" ddarrepo
return (c', u)
store :: DdarRepo -> Storer
store ddarrepo = fileStorer $ \k src _p -> do
let params =
[ Param "c"
, Param "-N"
, Param $ key2file k
, Param ddarrepo
, File src
]
liftIO $ boolSystem "ddar" params
{- Convert remote DdarRepo to host and path on remote end -}
splitRemoteDdarRepo :: DdarRepo -> (String, String)
splitRemoteDdarRepo ddarrepo =
(host, ddarrepo')
where
(host, remainder) = span (/= ':') ddarrepo
ddarrepo' = drop 1 remainder
{- Return the command and parameters to use for a ddar call that may need to be
- made on a remote repository. This will call ssh if needed. -}
ddarRemoteCall :: DdarRepo -> Char -> [CommandParam] -> Annex (String, [CommandParam])
ddarRemoteCall ddarrepo cmd params
| ddarLocal ddarrepo = return ("ddar", localParams)
| otherwise = do
remoteCachingParams <- sshCachingOptions (host, Nothing) []
return ("ssh", remoteCachingParams ++ remoteParams)
where
(host, ddarrepo') = splitRemoteDdarRepo ddarrepo
localParams = Param [cmd] : Param ddarrepo : params
remoteParams = Param host : Param "ddar" : Param [cmd] : Param ddarrepo' : params
{- Specialized ddarRemoteCall that includes extraction command and flags -}
ddarExtractRemoteCall :: DdarRepo -> Key -> Annex (String, [CommandParam])
ddarExtractRemoteCall ddarrepo k =
ddarRemoteCall ddarrepo 'x' [Param "--force-stdout", Param $ key2file k]
retrieve :: DdarRepo -> Retriever
retrieve ddarrepo = byteRetriever $ \k sink -> do
(cmd, params) <- ddarExtractRemoteCall ddarrepo k
let p = (proc cmd $ toCommand params) { std_out = CreatePipe }
(_, Just h, _, pid) <- liftIO $ createProcess p
liftIO (hClose h >> forceSuccessProcess p pid)
`after` (sink =<< liftIO (L.hGetContents h))
retrieveCheap :: Key -> FilePath -> Annex Bool
retrieveCheap _ _ = return False
remove :: DdarRepo -> Remover
remove ddarrepo key = do
(cmd, params) <- ddarRemoteCall ddarrepo 'd' [Param $ key2file key]
liftIO $ boolSystem cmd params
ddarDirectoryExists :: DdarRepo -> Annex (Either String Bool)
ddarDirectoryExists ddarrepo
| ddarLocal ddarrepo = do
maybeStatus <- liftIO $ tryJust (guard . isDoesNotExistError) $ getFileStatus ddarrepo
return $ case maybeStatus of
Left _ -> Right False
Right status -> Right $ isDirectory status
| otherwise = do
sshCachingParams <- sshCachingOptions (host, Nothing) []
exitCode <- liftIO $ safeSystem "ssh" $ sshCachingParams ++ params
case exitCode of
ExitSuccess -> return $ Right True
ExitFailure 1 -> return $ Right False
ExitFailure code -> return $ Left $ "ssh call " ++
show (Data.String.Utils.join " " $ toCommand params) ++
" failed with status " ++ show code
where
(host, ddarrepo') = splitRemoteDdarRepo ddarrepo
params =
[ Param host
, Param "test"
, Param "-d"
, Param ddarrepo'
]
{- Use "ddar t" to determine if a given key is present in a ddar archive -}
inDdarManifest :: DdarRepo -> Key -> Annex (Either String Bool)
inDdarManifest ddarrepo k = do
(cmd, params) <- ddarRemoteCall ddarrepo 't' []
let p = proc cmd $ toCommand params
liftIO $ catchMsgIO $ withHandle StdoutHandle createProcessSuccess p $ \h -> do
contents <- hGetContents h
return $ elem k' $ lines contents
where
k' = key2file k
checkKey :: DdarRepo -> CheckPresent
checkKey ddarrepo key = do
directoryExists <- ddarDirectoryExists ddarrepo
case directoryExists of
Left e -> error e
Right True -> either error return
=<< inDdarManifest ddarrepo key
Right False -> return False
ddarLocal :: DdarRepo -> Bool
ddarLocal = notElem ':'