added push notifier thread, currently a no-op

Hooked up everything that needs to notify on pushes. Note that
syncNewRemote does not notify. This is probably ok, and I'd need to thread
more state through to make it do so.

This is only set up to support a single push notification method; I didn't
use a NotificationBroadcaster. Partly because I don't yet know what info
about pushes needs to be communicated, so my data types are only
preliminary.

7 files changed, 100 insertions, 50 deletions

diff --git a/Assistant.hs b/Assistant.hs
index cb94ca462..b935d45dc 100644
--- a/Assistant.hs
+++ b/Assistant.hs
@@ -69,7 +69,9 @@
  - Thread 18: ConfigMonitor
  - 	Triggered by changes to the git-annex branch, checks for changed
  - 	config files, and reloads configs.
- - Thread 19: WebApp
+ - Thread 19: PushNotifier
+ - 	Notifies other repositories of pushes, using out of band signaling.
+ - Thread 20: WebApp
  - 	Spawns more threads as necessary to handle clients.
  - 	Displays the DaemonStatus.
  -
@@ -100,6 +102,11 @@
  - ScanRemotes (STM TMVar)
  - 	Remotes that have been disconnected, and should be scanned
  - 	are indicated by writing to this TMVar.
+ - BranchChanged (STM SampleVar)
+ - 	Changes to the git-annex branch are indicated by updating this
+ - 	SampleVar.
+ - PushNotifier (STM SampleVar)
+ - 	After successful pushes, this SampleVar is updated.
  - UrlRenderer (MVar)
  - 	A Yesod route rendering function is stored here. This allows
  - 	things that need to render Yesod routes to block until the webapp
@@ -133,6 +140,7 @@ import Assistant.Threads.NetWatcher
 import Assistant.Threads.TransferScanner
 import Assistant.Threads.TransferPoller
 import Assistant.Threads.ConfigMonitor
+import Assistant.Threads.PushNotifier
 #ifdef WITH_WEBAPP
 import Assistant.WebApp
 import Assistant.Threads.WebApp
@@ -180,6 +188,7 @@ startAssistant assistant daemonize webappwaiter = withThreadState $ \st -> do
 			transferslots <- newTransferSlots
 			scanremotes <- newScanRemoteMap
 			branchhandle <- newBranchChangeHandle
+			pushnotifier <- newPushNotifier
 #ifdef WITH_WEBAPP
 			urlrenderer <- newUrlRenderer
 #endif
@@ -191,19 +200,20 @@ startAssistant assistant daemonize webappwaiter = withThreadState $ \st -> do
 				, assist $ pairListenerThread st dstatus scanremotes urlrenderer
 #endif
 #endif
-				, assist $ pushThread st dstatus commitchan pushmap
-				, assist $ pushRetryThread st dstatus pushmap
+				, assist $ pushThread st dstatus commitchan pushmap pushnotifier
+				, assist $ pushRetryThread st dstatus pushmap pushnotifier
 				, assist $ mergeThread st dstatus transferqueue branchhandle
 				, assist $ transferWatcherThread st dstatus transferqueue
 				, assist $ transferPollerThread st dstatus
 				, assist $ transfererThread st dstatus transferqueue transferslots
 				, assist $ daemonStatusThread st dstatus
 				, assist $ sanityCheckerThread st dstatus transferqueue changechan
-				, assist $ mountWatcherThread st dstatus scanremotes
-				, assist $ netWatcherThread st dstatus scanremotes
-				, assist $ netWatcherFallbackThread st dstatus scanremotes
+				, assist $ mountWatcherThread st dstatus scanremotes pushnotifier
+				, assist $ netWatcherThread st dstatus scanremotes pushnotifier
+				, assist $ netWatcherFallbackThread st dstatus scanremotes pushnotifier
 				, assist $ transferScannerThread st dstatus scanremotes transferqueue
 				, assist $ configMonitorThread st dstatus branchhandle commitchan
+				, assist $ pushNotifierThread pushnotifier
 				, watch $ watchThread st dstatus transferqueue changechan
 				]
 			waitForTermination
diff --git a/Assistant/Pushes.hs b/Assistant/Pushes.hs
index f411dda07..649975fd1 100644
--- a/Assistant/Pushes.hs
+++ b/Assistant/Pushes.hs
@@ -10,6 +10,7 @@ module Assistant.Pushes where
 import Common.Annex
 
 import Control.Concurrent.STM
+import Control.Concurrent.MSampleVar
 import Data.Time.Clock
 import qualified Data.Map as M
 
@@ -17,6 +18,9 @@ import qualified Data.Map as M
 type PushMap = M.Map Remote UTCTime
 type FailedPushMap = TMVar PushMap
 
+{- Used to notify about successful pushes. -}
+newtype PushNotifier = PushNotifier (MSampleVar ())
+
 {- The TMVar starts empty, and is left empty when there are no
  - failed pushes. This way we can block until there are some failed pushes.
  -}
@@ -44,3 +48,12 @@ changeFailedPushMap v a = atomically $
 		store m
 			| m == M.empty = noop
 			| otherwise = putTMVar v $! m
+
+newPushNotifier :: IO PushNotifier
+newPushNotifier = PushNotifier <$> newEmptySV
+
+notifyPush :: PushNotifier -> IO ()
+notifyPush (PushNotifier sv) = writeSV sv ()
+
+waitPush :: PushNotifier -> IO ()
+waitPush (PushNotifier sv) = readSV sv
diff --git a/Assistant/Sync.hs b/Assistant/Sync.hs
index 6c167e2ea..e333877f2 100644
--- a/Assistant/Sync.hs
+++ b/Assistant/Sync.hs
@@ -36,9 +36,9 @@ import Control.Concurrent
  - the remotes have diverged from the local git-annex branch. Otherwise,
  - it's sufficient to requeue failed transfers.
  -}
-reconnectRemotes :: ThreadName -> ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> [Remote] -> IO ()
-reconnectRemotes _ _ _ _ [] = noop
-reconnectRemotes threadname st dstatus scanremotes rs = void $
+reconnectRemotes :: ThreadName -> ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> Maybe PushNotifier -> [Remote] -> IO ()
+reconnectRemotes _ _ _ _ _ [] = noop
+reconnectRemotes threadname st dstatus scanremotes pushnotifier rs = void $
 	alertWhile dstatus (syncAlert rs) $ do
 		(ok, diverged) <- sync
 			=<< runThreadState st (inRepo Git.Branch.current)
@@ -50,7 +50,7 @@ reconnectRemotes threadname st dstatus scanremotes rs = void $
 		sync (Just branch) = do
 			diverged <- manualPull st (Just branch) gitremotes
 			now <- getCurrentTime
-			ok <- pushToRemotes threadname now st Nothing gitremotes
+			ok <- pushToRemotes threadname now st pushnotifier Nothing gitremotes
 			return (ok, diverged)
 		{- No local branch exists yet, but we can try pulling. -}
 		sync Nothing = do
@@ -81,8 +81,8 @@ reconnectRemotes threadname st dstatus scanremotes rs = void $
  - them. While ugly, those branches are reserved for pushing by us, and
  - so our pushes will succeed.
  -}
-pushToRemotes :: ThreadName -> UTCTime -> ThreadState -> Maybe FailedPushMap -> [Remote] -> IO Bool
-pushToRemotes threadname now st mpushmap remotes = do
+pushToRemotes :: ThreadName -> UTCTime -> ThreadState -> Maybe PushNotifier -> Maybe FailedPushMap -> [Remote] -> IO Bool
+pushToRemotes threadname now st mpushnotifier mpushmap remotes = do
 	(g, branch, u) <- runThreadState st $ (,,)
 		<$> gitRepo
 		<*> inRepo Git.Branch.current
@@ -100,7 +100,9 @@ pushToRemotes threadname now st mpushmap remotes = do
 			updatemap succeeded []
 			let ok = null failed
 			if ok
-				then return ok
+				then do
+					maybe noop notifyPush mpushnotifier
+					return ok
 				else if shouldretry
 					then retry branch g u failed
 					else fallback branch g u failed
@@ -124,6 +126,8 @@ pushToRemotes threadname now st mpushmap remotes = do
 				]
 			(succeeded, failed) <- inParallel (pushfallback g u branch) rs
 			updatemap succeeded failed
+			unless (null succeeded) $
+				maybe noop notifyPush mpushnotifier
 			return $ null failed
 			
 		push g branch remote = Command.Sync.pushBranch remote branch g
@@ -157,4 +161,4 @@ manualPull st currentbranch remotes = do
 syncNewRemote :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> Remote -> IO ()
 syncNewRemote st dstatus scanremotes remote = do
 	runThreadState st $ updateSyncRemotes dstatus
-	void $ forkIO $ reconnectRemotes "SyncRemote" st dstatus scanremotes [remote]
+	void $ forkIO $ reconnectRemotes "SyncRemote" st dstatus scanremotes Nothing [remote]
diff --git a/Assistant/Threads/MountWatcher.hs b/Assistant/Threads/MountWatcher.hs
index 462f5843c..c36b544a7 100644
--- a/Assistant/Threads/MountWatcher.hs
+++ b/Assistant/Threads/MountWatcher.hs
@@ -15,6 +15,7 @@ import Assistant.ThreadedMonad
 import Assistant.DaemonStatus
 import Assistant.ScanRemotes
 import Assistant.Sync
+import Assistant.Pushes
 import qualified Annex
 import qualified Git
 import Utility.ThreadScheduler
@@ -38,20 +39,20 @@ import qualified Control.Exception as E
 thisThread :: ThreadName
 thisThread = "MountWatcher"
 
-mountWatcherThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> NamedThread
-mountWatcherThread st handle scanremotes = thread $
+mountWatcherThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> NamedThread
+mountWatcherThread st handle scanremotes pushnotifier = thread $
 #if WITH_DBUS
-	dbusThread st handle scanremotes
+	dbusThread st handle scanremotes pushnotifier
 #else
-	pollingThread st handle scanremotes
+	pollingThread st handle scanremotes pushnotifier
 #endif
 	where
 		thread = NamedThread thisThread
 
 #if WITH_DBUS
 
-dbusThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> IO ()
-dbusThread st dstatus scanremotes = E.catch (go =<< connectSession) onerr
+dbusThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> IO ()
+dbusThread st dstatus scanremotes pushnotifier = E.catch (go =<< connectSession) onerr
 	where
 		go client = ifM (checkMountMonitor client)
 			( do
@@ -64,7 +65,7 @@ dbusThread st dstatus scanremotes = E.catch (go =<< connectSession) onerr
 					listen client matcher $ \_event -> do
 						nowmounted <- currentMountPoints
 						wasmounted <- swapMVar mvar nowmounted
-						handleMounts st dstatus scanremotes wasmounted nowmounted
+						handleMounts st dstatus scanremotes pushnotifier wasmounted nowmounted
 			, do
 				runThreadState st $
 					warning "No known volume monitor available through dbus; falling back to mtab polling"
@@ -75,7 +76,7 @@ dbusThread st dstatus scanremotes = E.catch (go =<< connectSession) onerr
 			runThreadState st $
 				warning $ "Failed to use dbus; falling back to mtab polling (" ++ show e ++ ")"
 			pollinstead
-		pollinstead = pollingThread st dstatus scanremotes
+		pollinstead = pollingThread st dstatus scanremotes pushnotifier
 
 {- Examine the list of services connected to dbus, to see if there
  - are any we can use to monitor mounts. If not, will attempt to start one. -}
@@ -137,24 +138,24 @@ mountChanged = [gvfs True, gvfs False, kde, kdefallback]
 
 #endif
 
-pollingThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> IO ()
-pollingThread st dstatus scanremotes = go =<< currentMountPoints
+pollingThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> IO ()
+pollingThread st dstatus scanremotes pushnotifier = go =<< currentMountPoints
 	where
 		go wasmounted = do
 			threadDelaySeconds (Seconds 10)
 			nowmounted <- currentMountPoints
-			handleMounts st dstatus scanremotes wasmounted nowmounted
+			handleMounts st dstatus scanremotes pushnotifier wasmounted nowmounted
 			go nowmounted
 
-handleMounts :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> MountPoints -> MountPoints -> IO ()
-handleMounts st dstatus scanremotes wasmounted nowmounted =
-	mapM_ (handleMount st dstatus scanremotes . mnt_dir) $
+handleMounts :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> MountPoints -> MountPoints -> IO ()
+handleMounts st dstatus scanremotes pushnotifier wasmounted nowmounted =
+	mapM_ (handleMount st dstatus scanremotes pushnotifier . mnt_dir) $
 		S.toList $ newMountPoints wasmounted nowmounted
 
-handleMount :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> FilePath -> IO ()
-handleMount st dstatus scanremotes dir = do
+handleMount :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> FilePath -> IO ()
+handleMount st dstatus scanremotes pushnotifier dir = do
 	debug thisThread ["detected mount of", dir]
-	reconnectRemotes thisThread st dstatus scanremotes
+	reconnectRemotes thisThread st dstatus scanremotes (Just pushnotifier)
 		=<< filter (Git.repoIsLocal . Remote.repo)
 			<$> remotesUnder st dstatus dir
 
diff --git a/Assistant/Threads/NetWatcher.hs b/Assistant/Threads/NetWatcher.hs
index a8daa9435..2c637f414 100644
--- a/Assistant/Threads/NetWatcher.hs
+++ b/Assistant/Threads/NetWatcher.hs
@@ -15,6 +15,7 @@ import Assistant.ThreadedMonad
 import Assistant.DaemonStatus
 import Assistant.ScanRemotes
 import Assistant.Sync
+import Assistant.Pushes
 import Utility.ThreadScheduler
 import Remote.List
 import qualified Types.Remote as Remote
@@ -32,12 +33,12 @@ import qualified Control.Exception as E
 thisThread :: ThreadName
 thisThread = "NetWatcher"
 
-netWatcherThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> NamedThread
+netWatcherThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> NamedThread
 #if WITH_DBUS
-netWatcherThread st dstatus scanremotes = thread $
-	dbusThread st dstatus scanremotes
+netWatcherThread st dstatus scanremotes pushnotifier = thread $
+	dbusThread st dstatus scanremotes pushnotifier
 #else
-netWatcherThread _ _ _ = thread noop
+netWatcherThread _ _ _ _ = thread noop
 #endif
 	where
 		thread = NamedThread thisThread
@@ -47,17 +48,17 @@ netWatcherThread _ _ _ = thread noop
  - any networked remotes that may have not been routable for a
  - while (despite the local network staying up), are synced with
  - periodically. -}
-netWatcherFallbackThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> NamedThread
-netWatcherFallbackThread st dstatus scanremotes = thread $
+netWatcherFallbackThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> NamedThread
+netWatcherFallbackThread st dstatus scanremotes pushnotifier = thread $
 	runEvery (Seconds 3600) $
-		handleConnection st dstatus scanremotes
+		handleConnection st dstatus scanremotes pushnotifier
 	where
 		thread = NamedThread thisThread
 
 #if WITH_DBUS
 
-dbusThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> IO ()
-dbusThread st dstatus scanremotes = E.catch (go =<< connectSystem) onerr
+dbusThread :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> IO ()
+dbusThread st dstatus scanremotes pushnotifier = E.catch (go =<< connectSystem) onerr
 	where
 		go client = ifM (checkNetMonitor client)
 			( do
@@ -72,7 +73,7 @@ dbusThread st dstatus scanremotes = E.catch (go =<< connectSystem) onerr
 			warning $ "Failed to use dbus; falling back to polling (" ++ show e ++ ")"
 		handle = do
 			debug thisThread ["detected network connection"]
-			handleConnection st dstatus scanremotes
+			handleConnection st dstatus scanremotes pushnotifier
 
 {- Examine the list of services connected to dbus, to see if there
  - are any we can use to monitor network connections. -}
@@ -126,9 +127,9 @@ listenWicdConnections client callback =
 
 #endif
 
-handleConnection :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> IO ()
-handleConnection st dstatus scanremotes =
-	reconnectRemotes thisThread st dstatus scanremotes
+handleConnection :: ThreadState -> DaemonStatusHandle -> ScanRemoteMap -> PushNotifier -> IO ()
+handleConnection st dstatus scanremotes pushnotifier =
+	reconnectRemotes thisThread st dstatus scanremotes (Just pushnotifier)
 		=<< networkRemotes st
 
 {- Finds network remotes. -}
diff --git a/Assistant/Threads/PushNotifier.hs b/Assistant/Threads/PushNotifier.hs
new file mode 100644
index 000000000..cc5309712
--- /dev/null
+++ b/Assistant/Threads/PushNotifier.hs
@@ -0,0 +1,21 @@
+{- git-annex assistant push notification thread
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Assistant.Threads.PushNotifier where
+
+import Assistant.Common
+import Assistant.Pushes
+
+thisThread :: ThreadName
+thisThread = "PushNotifier"
+
+pushNotifierThread :: PushNotifier -> NamedThread
+pushNotifierThread pushnotifier = thread $ forever $ do
+	waitPush pushnotifier
+	-- TODO
+	where
+		thread = NamedThread thisThread
diff --git a/Assistant/Threads/Pusher.hs b/Assistant/Threads/Pusher.hs
index 4f3a2dd09..295ceddc9 100644
--- a/Assistant/Threads/Pusher.hs
+++ b/Assistant/Threads/Pusher.hs
@@ -24,8 +24,8 @@ thisThread :: ThreadName
 thisThread = "Pusher"
 
 {- This thread retries pushes that failed before. -}
-pushRetryThread :: ThreadState -> DaemonStatusHandle -> FailedPushMap -> NamedThread
-pushRetryThread st dstatus pushmap = thread $ runEvery (Seconds halfhour) $ do
+pushRetryThread :: ThreadState -> DaemonStatusHandle -> FailedPushMap -> PushNotifier -> NamedThread
+pushRetryThread st dstatus pushmap pushnotifier = thread $ runEvery (Seconds halfhour) $ do
 	-- We already waited half an hour, now wait until there are failed
 	-- pushes to retry.
 	topush <- getFailedPushesBefore pushmap (fromIntegral halfhour)
@@ -37,14 +37,14 @@ pushRetryThread st dstatus pushmap = thread $ runEvery (Seconds halfhour) $ do
 			]
 		now <- getCurrentTime
 		void $ alertWhile dstatus (pushRetryAlert topush) $
-			pushToRemotes thisThread now st (Just pushmap) topush
+			pushToRemotes thisThread now st (Just pushnotifier) (Just pushmap) topush
 	where
 		halfhour = 1800
 		thread = NamedThread thisThread
 
 {- This thread pushes git commits out to remotes soon after they are made. -}
-pushThread :: ThreadState -> DaemonStatusHandle -> CommitChan -> FailedPushMap -> NamedThread
-pushThread st dstatus commitchan pushmap = thread $ runEvery (Seconds 2) $ do
+pushThread :: ThreadState -> DaemonStatusHandle -> CommitChan -> FailedPushMap -> PushNotifier -> NamedThread
+pushThread st dstatus commitchan pushmap pushnotifier = thread $ runEvery (Seconds 2) $ do
 	-- We already waited two seconds as a simple rate limiter.
 	-- Next, wait until at least one commit has been made
 	commits <- getCommits commitchan
@@ -56,7 +56,7 @@ pushThread st dstatus commitchan pushmap = thread $ runEvery (Seconds 2) $ do
 				<$> getDaemonStatus dstatus
 			unless (null remotes) $ 
 				void $ alertWhile dstatus (pushAlert remotes) $
-					pushToRemotes thisThread now st (Just pushmap) remotes
+					pushToRemotes thisThread now st (Just pushnotifier) (Just pushmap) remotes
 		else do
 			debug thisThread
 				[ "delaying push of"