immediate queue flushing when annex.queuesize=1

Previously, it only flushed when the queue got larger than 1.

Also, make the queue auto-flush when items are added, rather than needing
to be flushed as a separate step. This simplifies the code and make it more
efficient too, as it avoids needing to read the queue out of the state to
check if it should be flushed.

Annex/Queue.hs

@@ -25,28 +25,33 @@ import qualified Git.UpdateIndex
 addCommand :: String -> [CommandParam] -> [FilePath] -> Annex ()
 addCommand command params files = do
 	q <- get
-	store <=< inRepo $ Git.Queue.addCommand command params files q
+	store <=< flushWhenFull <=< inRepo $
+		Git.Queue.addCommand command params files q
 
 {- Adds an update-index stream to the queue. -}
 addUpdateIndex :: Git.UpdateIndex.Streamer -> Annex ()
 addUpdateIndex streamer = do
 	q <- get
-	store <=< inRepo $ Git.Queue.addUpdateIndex streamer q
+	store <=< flushWhenFull <=< inRepo $
+		Git.Queue.addUpdateIndex streamer q
 
-{- Runs the queue if it is full. Should be called periodically. -}
-flushWhenFull :: Annex ()
-flushWhenFull = do
-	q <- get
-	when (Git.Queue.full q) flush
+{- Runs the queue if it is full. -}
+flushWhenFull :: Git.Queue.Queue -> Annex Git.Queue.Queue
+flushWhenFull q
+	| Git.Queue.full q = flush' q
+	| otherwise = return q
 
 {- Runs (and empties) the queue. -}
 flush :: Annex ()
 flush = do
 	q <- get
 	unless (0 == Git.Queue.size q) $ do
-		showStoringStateAction
-		q' <- inRepo $ Git.Queue.flush q
-		store q'
+		store =<< flush' q
+
+flush' :: Git.Queue.Queue -> Annex Git.Queue.Queue
+flush' q = do
+	showStoringStateAction
+	inRepo $ Git.Queue.flush q
 
 {- Gets the size of the queue. -}
 size :: Annex Int
@@ -70,5 +75,4 @@ mergeFrom st = case repoqueue st of
 	Just newq -> do
 		q <- get
 		let !q' = Git.Queue.merge q newq
-		store q'
-		flushWhenFull
+		store =<< flushWhenFull q'