run file transfers in threads, not processes

This should fix OSX/BSD issues with not noticing transfer information
files with kqueue. Now that threads are used, the thread can manage the
transfer slot allocation and deallocation by itself; much cleaner.

Assistant/Threads/TransferWatcher.hs

@@ -10,23 +10,20 @@ module Assistant.Threads.TransferWatcher where
 import Common.Annex
 import Assistant.ThreadedMonad
 import Assistant.DaemonStatus
-import Assistant.TransferSlots
 import Logs.Transfer
 import Utility.DirWatcher
 import Utility.Types.DirWatcher
-import Annex.BranchState
 
 import Data.Map as M
-import System.Posix.Process
 
 {- This thread watches for changes to the gitAnnexTransferDir,
  - and updates the DaemonStatus's map of ongoing transfers. -}
-transferWatcherThread :: ThreadState -> DaemonStatusHandle -> TransferSlots -> IO ()
-transferWatcherThread st dstatus transferslots = do
+transferWatcherThread :: ThreadState -> DaemonStatusHandle -> IO ()
+transferWatcherThread st dstatus = do
 	g <- runThreadState st $ fromRepo id
 	let dir = gitAnnexTransferDir g
 	createDirectoryIfMissing True dir
-	let hook a = Just $ runHandler st dstatus transferslots a
+	let hook a = Just $ runHandler st dstatus a
 	let hooks = mkWatchHooks
 		{ addHook = hook onAdd
 		, delHook = hook onDel
@@ -34,51 +31,36 @@ transferWatcherThread st dstatus transferslots = do
 		}
 	void $ watchDir dir (const False) hooks id
 
-type Handler = ThreadState -> DaemonStatusHandle -> TransferSlots -> FilePath -> Maybe FileStatus -> IO ()
+type Handler = ThreadState -> DaemonStatusHandle -> FilePath -> Maybe FileStatus -> IO ()
 
 {- Runs an action handler.
  -
  - Exceptions are ignored, otherwise a whole thread could be crashed.
  -}
-runHandler :: ThreadState -> DaemonStatusHandle -> TransferSlots -> Handler -> FilePath -> Maybe FileStatus -> IO ()
-runHandler st dstatus transferslots handler file filestatus = void $ do
+runHandler :: ThreadState -> DaemonStatusHandle -> Handler -> FilePath -> Maybe FileStatus -> IO ()
+runHandler st dstatus handler file filestatus = void $ do
         either print (const noop) =<< tryIO go
         where
-                go = handler st dstatus transferslots file filestatus
+                go = handler st dstatus file filestatus
 
 {- Called when there's an error with inotify. -}
 onErr :: Handler
-onErr _ _ _ msg _ = error msg
+onErr _ _ msg _ = error msg
 
 {- Called when a new transfer information file is written. -}
 onAdd :: Handler
-onAdd st dstatus _ file _ = case parseTransferFile file of
+onAdd st dstatus file _ = case parseTransferFile file of
 	Nothing -> noop
 	Just t -> runThreadState st $ go t =<< checkTransfer t
 	where
 		go _ Nothing = noop -- transfer already finished
 		go t (Just info) = adjustTransfers dstatus $
 			M.insertWith' merge t info
-		-- preseve shouldWait flag, which is not written to disk
-		merge new old = new { shouldWait = shouldWait old }
+		-- preseve transferTid, which is not written to disk
+		merge new old = new { transferTid = transferTid old }
 
-{- Called when a transfer information file is removed.
- -
- - When the transfer process is a child of this process, wait on it
- - to avoid zombies.
- -}
+{- Called when a transfer information file is removed. -}
 onDel :: Handler
-onDel st dstatus transferslots file _ = case parseTransferFile file of
+onDel st dstatus file _ = case parseTransferFile file of
 	Nothing -> noop
-	Just t -> maybe noop waitchild
-		=<< runThreadState st (removeTransfer dstatus t)
-	where
-		waitchild info
-			| shouldWait info = case transferPid info of
-				Nothing -> noop
-				Just pid -> do
-					void $ tryIO $ 
-						getProcessStatus True False pid
-					runThreadState st invalidateCache
-					transferComplete transferslots
-			| otherwise = noop	
+	Just t -> void $ runThreadState st $ removeTransfer dstatus t