get, move, copy, mirror: Added --failed switch which retries failed copies/moves

Note that get --from foo --failed will get things that a previous get --from bar
tried and failed to get, etc. I considered making --failed only retry
transfers from the same remote, but it was easier, and seems more useful,
to not have the same remote requirement.

Noisy due to some refactoring into Types/

Types/Transfer.hs

@@ -0,0 +1,47 @@
+{- git-annex transfer types
+ -
+ - Copyright 2012 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Types.Transfer where
+
+import Types
+import Utility.PID
+
+import Data.Time.Clock.POSIX
+import Control.Concurrent
+
+{- Enough information to uniquely identify a transfer, used as the filename
+ - of the transfer information file. -}
+data Transfer = Transfer
+	{ transferDirection :: Direction
+	, transferUUID :: UUID
+	, transferKey :: Key
+	}
+	deriving (Eq, Ord, Read, Show)
+
+{- Information about a Transfer, stored in the transfer information file.
+ -
+ - Note that the associatedFile may not correspond to a file in the local
+ - git repository. It's some file, possibly relative to some directory,
+ - of some repository, that was acted on to initiate the transfer.
+ -}
+data TransferInfo = TransferInfo
+	{ startedTime :: Maybe POSIXTime
+	, transferPid :: Maybe PID
+	, transferTid :: Maybe ThreadId
+	, transferRemote :: Maybe Remote
+	, bytesComplete :: Maybe Integer
+	, associatedFile :: Maybe FilePath
+	, transferPaused :: Bool
+	}
+	deriving (Show, Eq, Ord)
+
+stubTransferInfo :: TransferInfo
+stubTransferInfo = TransferInfo Nothing Nothing Nothing Nothing Nothing Nothing False
+
+data Direction = Upload | Download
+	deriving (Eq, Ord, Read, Show)
+