multicast: New command, uses uftp to multicast annexed files, for eg a classroom setting.

This commit was supported by the NSF-funded DataLad project.

Logs/Multicast.hs

@@ -0,0 +1,33 @@
+{- git-annex multicast fingerprint log
+ -
+ - Copyright 2017 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Logs.Multicast (
+	Fingerprint(..),
+	recordFingerprint,
+	knownFingerPrints,
+) where
+
+import Data.Time.Clock.POSIX
+
+import Annex.Common
+import qualified Annex.Branch
+import Logs
+import Logs.UUIDBased
+
+import qualified Data.Map as M
+
+newtype Fingerprint = Fingerprint String
+	deriving (Eq, Read, Show)
+
+recordFingerprint :: Fingerprint -> UUID -> Annex ()
+recordFingerprint fp uuid = do
+	ts <- liftIO getPOSIXTime
+	Annex.Branch.change multicastLog $
+		showLog show . changeLog ts uuid fp . parseLog readish
+
+knownFingerPrints :: Annex (M.Map UUID Fingerprint)
+knownFingerPrints = simpleMap . parseLog readish <$> Annex.Branch.get activityLog