pushed Assistant monad down into DaemonStatus code

Currently have three old versions of functions that more reworking is
needed to remove: getDaemonStatusOld, modifyDaemonStatusOld_, and
modifyDaemonStatusOld

Assistant/TransferSlots.hs

@@ -17,20 +17,22 @@ import qualified Control.Exception as E
 import Control.Concurrent
 import qualified Control.Concurrent.MSemN as MSemN
 
+type TransferGenerator = Assistant (Maybe (Transfer, TransferInfo, IO ()))
+
 {- Waits until a transfer slot becomes available, then runs a
  - TransferGenerator, and then runs the transfer action in its own thread. 
  -}
-inTransferSlot :: TransferSlotRunner
-inTransferSlot dstatus s gen = do
-	MSemN.wait s 1
-	runTransferThread dstatus s =<< gen
+inTransferSlot :: TransferGenerator -> Assistant ()
+inTransferSlot gen = do
+	flip MSemN.wait 1 <<~ transferSlots
+	runTransferThread =<< gen
 
 {- Runs a TransferGenerator, and its transfer action,
  - without waiting for a slot to become available. -}
-inImmediateTransferSlot :: TransferSlotRunner
-inImmediateTransferSlot dstatus s gen = do
-	MSemN.signal s (-1)
-	runTransferThread dstatus s =<< gen
+inImmediateTransferSlot :: TransferGenerator -> Assistant ()
+inImmediateTransferSlot gen = do
+	flip MSemN.signal (-1) <<~ transferSlots
+	runTransferThread =<< gen
 
 {- Runs a transfer action, in an already allocated transfer slot.
  - Once it finishes, frees the transfer slot.
@@ -42,24 +44,26 @@ inImmediateTransferSlot dstatus s gen = do
  - then pausing the thread until a ResumeTransfer exception is raised,
  - then rerunning the action.
  -}
-runTransferThread :: DaemonStatusHandle -> TransferSlots -> Maybe (Transfer, TransferInfo, IO ()) -> IO ()
-runTransferThread _ s  Nothing = MSemN.signal s 1
-runTransferThread dstatus s (Just (t, info, a)) = do
-	tid <- forkIO go
-	updateTransferInfo dstatus t $ info { transferTid = Just tid }
+runTransferThread :: Maybe (Transfer, TransferInfo, IO ()) -> Assistant ()
+runTransferThread Nothing = flip MSemN.signal 1 <<~ transferSlots
+runTransferThread (Just (t, info, a)) = do
+	d <- getAssistant id
+	tid <- liftIO $ forkIO $ go d
+	updateTransferInfo t $ info { transferTid = Just tid }
 	where
-		go = catchPauseResume a
-		pause = catchPauseResume $ runEvery (Seconds 86400) noop
+		go d = catchPauseResume d a
+		pause d = catchPauseResume d $ runEvery (Seconds 86400) noop
 		{- Note: This must use E.try, rather than E.catch.
 		 - When E.catch is used, and has called go in its exception
 		 - handler, Control.Concurrent.throwTo will block sometimes
 		 - when signaling. Using E.try avoids the problem. -}
-		catchPauseResume a' = do
+		catchPauseResume d a' = do
 			r <- E.try a' :: IO (Either E.SomeException ())
 			case r of
 				Left e -> case E.fromException e of
-					Just PauseTransfer -> pause
-					Just ResumeTransfer -> go
-					_ -> done
-				_ -> done
-		done = MSemN.signal s 1
+					Just PauseTransfer -> pause d
+					Just ResumeTransfer -> go d
+					_ -> done d
+				_ -> done d
+		done d = flip runAssistant d $ 
+			flip MSemN.signal 1 <<~ transferSlots