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/ActionItem.hs

@@ -0,0 +1,54 @@
+{- items that a command can act on
+ -
+ - Copyright 2016 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
+
+module Types.ActionItem where
+
+import Types.Key
+import Types.Transfer
+import Git.FilePath
+
+import Data.Maybe
+
+data ActionItem 
+	= ActionItemAssociatedFile AssociatedFile
+	| ActionItemKey
+	| ActionItemBranchFilePath BranchFilePath
+	| ActionItemFailedTransfer Transfer TransferInfo
+
+class MkActionItem t where
+	mkActionItem :: t -> ActionItem
+
+instance MkActionItem AssociatedFile where
+	mkActionItem = ActionItemAssociatedFile
+
+instance MkActionItem Key where
+	mkActionItem _ = ActionItemKey
+
+instance MkActionItem BranchFilePath where
+	mkActionItem = ActionItemBranchFilePath
+
+instance MkActionItem (Transfer, TransferInfo) where
+	mkActionItem = uncurry ActionItemFailedTransfer
+
+actionItemDesc :: ActionItem -> Key -> String
+actionItemDesc (ActionItemAssociatedFile (Just f)) _ = f
+actionItemDesc (ActionItemAssociatedFile Nothing) k = key2file k
+actionItemDesc ActionItemKey k = key2file k
+actionItemDesc (ActionItemBranchFilePath bfp) _ = descBranchFilePath bfp
+actionItemDesc (ActionItemFailedTransfer _ i) k = 
+	fromMaybe (key2file k) (associatedFile i)
+
+actionItemWorkTreeFile :: ActionItem -> Maybe FilePath
+actionItemWorkTreeFile (ActionItemAssociatedFile af) = af
+actionItemWorkTreeFile _ = Nothing
+
+actionItemTransferDirection :: ActionItem -> Maybe Direction
+actionItemTransferDirection (ActionItemFailedTransfer t _) = Just $
+	transferDirection t
+actionItemTransferDirection _ = Nothing

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)
+