git-annex/Types/Remote.hs
Joey Hess 58f727afdd resume interrupted chunked uploads
Leverage the new chunked remotes to automatically resume uploads.
Sort of like rsync, although of course not as efficient since this
needs to start at a chunk boundry.

But, unlike rsync, this method will work for S3, WebDAV, external
special remotes, etc, etc. Only directory special remotes so far,
but many more soon!

This implementation will also allow starting an upload from one repository,
interrupting it, and then resuming the upload to the same remote from
an entirely different repository.

Note that I added a comment that storeKey should atomically move the content
into place once it's all received. This was already an undocumented
requirement -- it's necessary for hasKey to work reliably. This resume code
just uses hasKey to find the first chunk that's missing.

Note that if there are two uploads of the same key to the same chunked remote,
one might resume at the point the other had gotten to, but both will then
redundantly upload. As before.

In the non-resume case, this adds one hasKey call per storeKey, and only
if the remote is configured to use chunks. Future work: Try to eliminate that
hasKey. Notice that eg, `git annex copy --to` checks if the key is present
before sending it, so is already running hasKey.. which could perhaps
be cached and reused.

However, this additional overhead is not very large compared with
transferring an entire large file, and the ability to resume
is certianly worth it. There is an optimisation in place for small files,
that avoids trying to resume if the whole file fits within one chunk.

This commit was sponsored by Georg Bauer.
2014-07-28 14:35:52 -04:00

109 lines
3.5 KiB
Haskell

{- git-annex remotes types
-
- Most things should not need this, using Types instead
-
- Copyright 2011-2014 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Types.Remote
( RemoteConfigKey
, RemoteConfig
, RemoteTypeA(..)
, RemoteA(..)
, Availability(..)
)
where
import Data.Map as M
import Data.Ord
import qualified Git
import Types.Key
import Types.UUID
import Types.GitConfig
import Types.Availability
import Types.Creds
import Config.Cost
import Utility.Metered
import Git.Types
import Utility.SafeCommand
type RemoteConfigKey = String
type RemoteConfig = M.Map RemoteConfigKey String
{- There are different types of remotes. -}
data RemoteTypeA a = RemoteType {
-- human visible type name
typename :: String,
-- enumerates remotes of this type
enumerate :: a [Git.Repo],
-- generates a remote of this type
generate :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> a (Maybe (RemoteA a)),
-- initializes or changes a remote
setup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> a (RemoteConfig, UUID)
}
instance Eq (RemoteTypeA a) where
x == y = typename x == typename y
{- An individual remote. -}
data RemoteA a = Remote {
-- each Remote has a unique uuid
uuid :: UUID,
-- each Remote has a human visible name
name :: RemoteName,
-- Remotes have a use cost; higher is more expensive
cost :: Cost,
-- Transfers a key's contents from disk to the remote.
-- The key should not appear to be present on the remote until
-- all of its contents have been transferred.
storeKey :: Key -> AssociatedFile -> MeterUpdate -> a Bool,
-- Retrieves a key's contents to a file.
-- (The MeterUpdate does not need to be used if it retrieves
-- directly to the file, and not to an intermediate file.)
retrieveKeyFile :: Key -> AssociatedFile -> FilePath -> MeterUpdate -> a Bool,
-- retrieves a key's contents to a tmp file, if it can be done cheaply
retrieveKeyFileCheap :: Key -> FilePath -> a Bool,
-- removes a key's contents (succeeds if the contents are not present)
removeKey :: Key -> a Bool,
-- Checks if a key is present in the remote; if the remote
-- cannot be accessed returns a Left error message.
hasKey :: Key -> a (Either String Bool),
-- Some remotes can check hasKey without an expensive network
-- operation.
hasKeyCheap :: Bool,
-- Some remotes can provide additional details for whereis.
whereisKey :: Maybe (Key -> a [String]),
-- Some remotes can run a fsck operation on the remote,
-- without transferring all the data to the local repo
-- The parameters are passed to the fsck command on the remote.
remoteFsck :: Maybe ([CommandParam] -> a (IO Bool)),
-- Runs an action to repair the remote's git repository.
repairRepo :: Maybe (a Bool -> a (IO Bool)),
-- a Remote has a persistent configuration store
config :: RemoteConfig,
-- git repo for the Remote
repo :: Git.Repo,
-- a Remote's configuration from git
gitconfig :: RemoteGitConfig,
-- a Remote can be assocated with a specific local filesystem path
localpath :: Maybe FilePath,
-- a Remote can be known to be readonly
readonly :: Bool,
-- a Remote can be globally available. (Ie, "in the cloud".)
availability :: Availability,
-- the type of the remote
remotetype :: RemoteTypeA a
}
instance Show (RemoteA a) where
show remote = "Remote { name =\"" ++ name remote ++ "\" }"
-- two remotes are the same if they have the same uuid
instance Eq (RemoteA a) where
x == y = uuid x == uuid y
instance Ord (RemoteA a) where
compare = comparing uuid