ensure that git-annex branch is pushed after a successful transfer

I now have this topology working:

   assistant ---> {bare repo, special remote} <--- assistant

And, I think, also this one:

        +----------- bare repo --------+
        v                              v
  assistant ---> special remote <--- assistant

While before with assistant <---> assistant connections, both sides got
location info updated after a transfer, in this topology, the bare repo
*might* get its location info updated, but the other assistant has no way to
know that it did. And a special remote doesn't record location info,
so transfers to it won't propigate out location log changes at all.

So, for these to work, after a transfer succeeds, the git-annex branch
needs to be pushed. This is done by recording a synthetic commit has
occurred, which lets the pusher handle pushing out the change (which will
include actually committing any still journalled changes to the git-annex
branch).

Of course, this means rather a lot more syncing action than happened
before. At least the pusher bundles together very close together pushes,
somewhat. Currently it just waits 2 seconds between each push.

Assistant.hs

@@ -197,7 +197,7 @@ startAssistant assistant daemonize webappwaiter = withThreadState $ \st -> do
 			mapM_ (startthread dstatus)
 				[ watch $ commitThread st changechan commitchan transferqueue dstatus
 #ifdef WITH_WEBAPP
-				, assist $ webAppThread (Just st) dstatus scanremotes transferqueue transferslots pushnotifier urlrenderer Nothing webappwaiter
+				, assist $ webAppThread (Just st) dstatus scanremotes transferqueue transferslots pushnotifier commitchan urlrenderer Nothing webappwaiter
 #ifdef WITH_PAIRING
 				, assist $ pairListenerThread st dstatus scanremotes urlrenderer
 #endif
@@ -207,7 +207,7 @@ startAssistant assistant daemonize webappwaiter = withThreadState $ \st -> do
 				, assist $ mergeThread st dstatus transferqueue branchhandle
 				, assist $ transferWatcherThread st dstatus transferqueue
 				, assist $ transferPollerThread st dstatus
-				, assist $ transfererThread st dstatus transferqueue transferslots
+				, assist $ transfererThread st dstatus transferqueue transferslots commitchan
 				, assist $ daemonStatusThread st dstatus
 				, assist $ sanityCheckerThread st dstatus transferqueue changechan
 				, assist $ mountWatcherThread st dstatus scanremotes pushnotifier

Assistant/Commits.hs

@@ -9,12 +9,9 @@ module Assistant.Commits where
 
 import Utility.TSet
 
-import Data.Time.Clock
-
 type CommitChan = TSet Commit
 
-data Commit = Commit UTCTime
-	deriving (Show)
+data Commit = Commit
 
 newCommitChan :: IO CommitChan
 newCommitChan = newTSet
@@ -30,5 +27,5 @@ refillCommits :: CommitChan -> [Commit] -> IO ()
 refillCommits = putTSet
 
 {- Records a commit in the channel. -}
-recordCommit :: CommitChan -> Commit -> IO ()
-recordCommit = putTSet1
+recordCommit :: CommitChan -> IO ()
+recordCommit = flip putTSet1 Commit

Assistant/Threads/Committer.hs

@@ -65,7 +65,7 @@ commitThread st changechan commitchan transferqueue dstatus = thread $ do
 							]
 						void $ alertWhile dstatus commitAlert $
 							runThreadState st commitStaged
-						recordCommit commitchan (Commit time)
+						recordCommit commitchan
 					else refill readychanges
 			else refill changes
 	where

Assistant/Threads/ConfigMonitor.hs

@@ -24,7 +24,6 @@ import qualified Git.LsTree as LsTree
 import qualified Annex.Branch
 import qualified Annex
 
-import Data.Time.Clock
 import qualified Data.Set as S
 
 thisThread :: ThreadName
@@ -56,8 +55,7 @@ configMonitorThread st dstatus branchhandle commitchan = thread $ do
 				reloadConfigs st dstatus changedconfigs
 				{- Record a commit to get this config
 				 - change pushed out to remotes. -}
-				time <- getCurrentTime
-				recordCommit commitchan (Commit time)
+				recordCommit commitchan
 			go r new
 
 {- Config files, and their checksums. -}

Assistant/Threads/Pusher.hs

@@ -49,12 +49,12 @@ pushThread st dstatus commitchan pushmap pushnotifier = thread $ runEvery (Secon
 	-- Next, wait until at least one commit has been made
 	commits <- getCommits commitchan
 	-- Now see if now's a good time to push.
-	now <- getCurrentTime
-	if shouldPush now commits
+	if shouldPush commits
 		then do
 			remotes <- filter pushable . syncRemotes
 				<$> getDaemonStatus dstatus
-			unless (null remotes) $ 
+			unless (null remotes) $ do
+				now <- getCurrentTime
 				void $ alertWhile dstatus (pushAlert remotes) $
 					pushToRemotes thisThread now st (Just pushnotifier) (Just pushmap) remotes
 		else do
@@ -77,7 +77,7 @@ pushThread st dstatus commitchan pushmap pushnotifier = thread $ runEvery (Secon
  - already determines batches of changes, so we can't easily determine
  - batches better.
  -}
-shouldPush :: UTCTime -> [Commit] -> Bool
-shouldPush _now commits
+shouldPush :: [Commit] -> Bool
+shouldPush commits
 	| not (null commits) = True
 	| otherwise = False

Assistant/Threads/Transferrer.hs

@@ -13,6 +13,7 @@ import Assistant.DaemonStatus
 import Assistant.TransferQueue
 import Assistant.TransferSlots
 import Assistant.Alert
+import Assistant.Commits
 import Logs.Transfer
 import Logs.Location
 import Annex.Content
@@ -30,20 +31,20 @@ maxTransfers :: Int
 maxTransfers = 1
 
 {- Dispatches transfers from the queue. -}
-transfererThread :: ThreadState -> DaemonStatusHandle -> TransferQueue -> TransferSlots -> NamedThread
-transfererThread st dstatus transferqueue slots = thread $ go =<< readProgramFile
+transfererThread :: ThreadState -> DaemonStatusHandle -> TransferQueue -> TransferSlots -> CommitChan -> NamedThread
+transfererThread st dstatus transferqueue slots commitchan = thread $ go =<< readProgramFile
 	where
 		thread = NamedThread thisThread
 		go program = forever $ inTransferSlot dstatus slots $
-			maybe (return Nothing) (uncurry $ startTransfer st dstatus program)
+			maybe (return Nothing) (uncurry $ startTransfer st dstatus commitchan program)
 				=<< getNextTransfer transferqueue dstatus notrunning
 		{- Skip transfers that are already running. -}
 		notrunning = isNothing . startedTime
 
 {- By the time this is called, the daemonstatus's transfer map should
  - already have been updated to include the transfer. -}
-startTransfer :: ThreadState -> DaemonStatusHandle -> FilePath -> Transfer -> TransferInfo -> TransferGenerator
-startTransfer st dstatus program t info = case (transferRemote info, associatedFile info) of
+startTransfer :: ThreadState -> DaemonStatusHandle -> CommitChan -> FilePath -> Transfer -> TransferInfo -> TransferGenerator
+startTransfer st dstatus commitchan program t info = case (transferRemote info, associatedFile info) of
 	(Just remote, Just file) -> ifM (runThreadState st $ shouldTransfer t info)
 		( do
 			debug thisThread [ "Transferring:" , show t ]
@@ -66,11 +67,19 @@ startTransfer st dstatus program t info = case (transferRemote info, associatedF
 			{- Alerts are only shown for successful transfers.
 			 - Transfers can temporarily fail for many reasons,
 			 - so there's no point in bothering the user about
-			 - those. The assistant should recover. -}
-			whenM ((==) ExitSuccess <$> waitForProcess pid) $ void $
-				addAlert dstatus $
+			 - those. The assistant should recover.
+			 -
+			 - Also, after a successful transfer, the location
+			 - log has changed. Indicate that a commit has been
+			 - made, in order to queue a push of the git-annex
+			 - branch out to remotes that did not participate
+			 - in the transfer.
+			 -}
+			whenM ((==) ExitSuccess <$> waitForProcess pid) $ do
+				void $ addAlert dstatus $
 					makeAlertFiller True $
 						transferFileAlert direction True file
+				recordCommit commitchan
 			where
 				params =
 					[ Param "transferkey"

Assistant/Threads/WebApp.hs

@@ -33,6 +33,7 @@ import Assistant.ScanRemotes
 import Assistant.TransferQueue
 import Assistant.TransferSlots
 import Assistant.Pushes
+import Assistant.Commits
 import Utility.WebApp
 import Utility.FileMode
 import Utility.TempFile
@@ -57,11 +58,12 @@ webAppThread
 	-> TransferQueue
 	-> TransferSlots
 	-> PushNotifier
+	-> CommitChan
 	-> UrlRenderer
 	-> Maybe (IO String)
 	-> Maybe (Url -> FilePath -> IO ())
 	-> NamedThread
-webAppThread mst dstatus scanremotes transferqueue transferslots pushnotifier urlrenderer postfirstrun onstartup = thread $ do
+webAppThread mst dstatus scanremotes transferqueue transferslots pushnotifier commitchan urlrenderer postfirstrun onstartup = thread $ do
 	webapp <- WebApp
 		<$> pure mst
 		<*> pure dstatus
@@ -69,6 +71,7 @@ webAppThread mst dstatus scanremotes transferqueue transferslots pushnotifier ur
 		<*> pure transferqueue
 		<*> pure transferslots
 		<*> pure pushnotifier
+		<*> pure commitchan
 		<*> (pack <$> genRandomToken)
 		<*> getreldir mst
 		<*> pure $(embed "static")

Assistant/WebApp/Types.hs

@@ -18,6 +18,7 @@ import Assistant.ScanRemotes
 import Assistant.TransferQueue
 import Assistant.TransferSlots
 import Assistant.Pushes
+import Assistant.Commits
 import Assistant.Alert
 import Assistant.Pairing
 import Utility.NotificationBroadcaster
@@ -40,6 +41,7 @@ data WebApp = WebApp
 	, transferQueue :: TransferQueue
 	, transferSlots :: TransferSlots
 	, pushNotifier :: PushNotifier
+	, commitChan :: CommitChan
 	, secretToken :: Text
 	, relDir :: Maybe FilePath
 	, getStatic :: Static

Assistant/WebApp/Utility.hs

@@ -135,9 +135,10 @@ startTransfer t = do
 			let st = fromJust $ threadState webapp
 			let dstatus = daemonStatus webapp
 			let slots = transferSlots webapp
+			let commitchan = commitChan webapp
 			liftIO $ inImmediateTransferSlot dstatus slots $ do
 				program <- readProgramFile
-				Transferrer.startTransfer st dstatus program t info
+				Transferrer.startTransfer st dstatus commitchan program t info
 
 getCurrentTransfers :: Handler TransferMap
 getCurrentTransfers = currentTransfers

Command/WebApp.hs

@@ -16,6 +16,7 @@ import Assistant.ScanRemotes
 import Assistant.TransferQueue
 import Assistant.TransferSlots
 import Assistant.Pushes
+import Assistant.Commits
 import Assistant.Threads.WebApp
 import Assistant.WebApp
 import Assistant.Install
@@ -106,11 +107,13 @@ firstRun = do
 	transferslots <- newTransferSlots
 	urlrenderer <- newUrlRenderer
 	pushnotifier <- newPushNotifier
+	commitchan <- newCommitChan
 	v <- newEmptyMVar
 	let callback a = Just $ a v
 	void $ runNamedThread dstatus $
 		webAppThread Nothing dstatus scanremotes
-			transferqueue transferslots pushnotifier urlrenderer
+			transferqueue transferslots pushnotifier commitchan
+			urlrenderer
 			(callback signaler) (callback mainthread)
 	where
 		signaler v = do