added git-annex remotedaemon

So far, handling connecting to git-annex-shell notifychanges, and
pulling immediately when a change is pushed to a remote.

A little bit buggy (crashes after the first pull), but it already works!

This commit was sponsored by Mark Sheppard.

RemoteDaemon/Core.hs

@@ -0,0 +1,114 @@
+{- git-remote-daemon core
+ -
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module RemoteDaemon.Core (runForeground) where
+
+import qualified Annex
+import Common
+import Types.GitConfig
+import RemoteDaemon.Types
+import RemoteDaemon.Transport
+import qualified Git
+import qualified Git.Types as Git
+import qualified Git.CurrentRepo
+import Utility.SimpleProtocol
+
+import Control.Concurrent.Async
+import Control.Concurrent.Chan
+import Network.URI
+import qualified Data.Map as M
+
+runForeground :: IO ()
+runForeground = do
+	ichan <- newChan :: IO (Chan Consumed)
+	ochan <- newChan :: IO (Chan Emitted)
+
+	void $ async $ controller ichan ochan
+
+	let reader = forever $ do
+		l <- getLine
+		case parseMessage l of
+			Nothing -> error $ "protocol error: " ++ l
+			Just cmd -> writeChan ichan cmd
+	let writer = forever $ do
+		msg <- readChan ochan
+		putStrLn $ unwords $ formatMessage msg
+		hFlush stdout
+	
+	-- If the reader or writer fails, for example because stdin/stdout
+	-- gets closed, kill the other one, and throw an exception which
+	-- will take down the daemon.
+	void $ concurrently reader writer
+
+type RemoteMap = M.Map Git.Repo (IO (), Chan Consumed)
+
+-- Runs the transports, dispatching messages to them, and handling
+-- the main control messages.
+controller :: Chan Consumed -> Chan Emitted -> IO ()
+controller ichan ochan = do
+	m <- getRemoteMap ochan
+	startrunning m
+	go False m
+  where
+	go paused m = do
+		cmd <- readChan ichan
+		case cmd of
+			RELOAD -> do
+				m' <- getRemoteMap ochan
+				let common = M.intersection m m'
+				let new = M.difference m' m
+				let old = M.difference m m'
+				stoprunning old
+				unless paused $
+					startrunning new
+				go paused (M.union common new)
+			PAUSE -> do
+				stoprunning m
+				go True m
+			RESUME -> do
+				when paused $
+					startrunning m
+				go False m
+			STOP -> exitSuccess
+			-- All remaining messages are sent to
+			-- all Transports.
+			msg -> do
+				unless paused $
+					forM_ chans (`writeChan` msg)
+				go paused m
+	  where
+		chans = map snd (M.elems m)
+
+	startrunning m = forM_ (M.elems m) startrunning'
+	startrunning' (transport, _) = void $ async transport
+	
+	-- Ask the transport nicely to stop.
+	stoprunning m = forM_ (M.elems m) stoprunning'
+	stoprunning' (_, c) = writeChan c STOP
+
+getRemoteMap :: Chan Emitted -> IO RemoteMap
+getRemoteMap ochan = do
+	annexstate <- Annex.new =<< Git.CurrentRepo.get
+	genRemoteMap annexstate ochan
+
+-- Generates a map with a transport for each supported remote in the git repo,
+-- except those that have annex.sync = false
+genRemoteMap :: Annex.AnnexState -> Chan Emitted -> IO RemoteMap
+genRemoteMap annexstate ochan = M.fromList . catMaybes <$> mapM gen rs
+  where
+	rs = Git.remotes (Annex.repo annexstate)
+	gen r = case Git.location r of
+		Git.Url u -> case M.lookup (uriScheme u) remoteTransports of
+			Just transport
+				| remoteAnnexSync (extractRemoteGitConfig r (Git.repoDescribe r)) -> do
+					ichan <- newChan :: IO (Chan Consumed)
+					return $ Just
+						( r
+						, (transport r (Git.repoDescribe r) annexstate ichan ochan, ichan)
+						)
+			_ -> return Nothing
+		_ -> return Nothing