update PacketQueue in preparation for request thread

1 files changed, 15 insertions, 11 deletions

diff --git a/src/Data/PacketQueue.hs b/src/Data/PacketQueue.hs
index 1e79b851..57845ae5 100644
--- a/src/Data/PacketQueue.hs
+++ b/src/Data/PacketQueue.hs
@@ -10,6 +10,7 @@ module Data.PacketQueue
     , new
     , newOverwrite
     , dequeue
+    , dequeueOrGetMissing
     , markButNotDequeue
     , enqueue
     , observeOutOfBand
@@ -36,7 +37,7 @@ import Debug.Trace
 
 data PacketQueue a = PacketQueue
     { pktq    :: TArray Word32 (Maybe a)
-    , seqno   :: TVar Word32
+    , seqno   :: TVar Word32 -- (buffer_start)
     , qsize   :: Word32
     , buffend :: TVar Word32 -- on incoming, next packet they'll send + 1
     , qOverWriteMode :: Bool -- TODO: Remove me, use Data.CyclicBuffer instead.
@@ -85,28 +86,31 @@ newOverwrite capacity seqstart = do
         , qOverWriteMode = True
         }
 
+-- | Update the packet queue given:
+--      * packet queue
+--      * the number of next lossless packet they intend to send you
 observeOutOfBand :: PacketQueue a -> Word32-> STM ()
-observeOutOfBand PacketQueue { seqno, qsize, buffend } no = do
+observeOutOfBand PacketQueue { seqno, qsize, buffend } numberOfNextLosslessPacketThatTheyWillSend = do
     low <- readTVar seqno
-    let proj = no - low
+    let proj = numberOfNextLosslessPacketThatTheyWillSend - low
     -- Ignore packet if out of range.
     when ( proj < qsize) $ do
-    modifyTVar' buffend (\be -> if be - low <= proj then no + 1 else be)
+    modifyTVar' buffend (\be -> if be - low <= proj then numberOfNextLosslessPacketThatTheyWillSend + 1 else be)
 
--- | If buffend < seqno then return expected packet numbers for all
+-- | If seqno < buffend then return expected packet numbers for all
 --   the Nothings in the array between them.
 --   Otherwise, behave as 'dequeue' would.
 dequeueOrGetMissing :: PacketQueue a -> STM (Either [Word32] a)
 dequeueOrGetMissing PacketQueue { pktq, seqno, qsize, buffend } = do
-    i0 <- readTVar seqno
-    be <- readTVar buffend
-    if i0 < be
+    seqno0 <- readTVar seqno
+    buffend0 <- readTVar buffend
+    if seqno0 < buffend0
       then do
-        maybes <- mapM (readArray pktq) (take (fromIntegral qsize) $ map (`mod` qsize) [ be .. i0 ])
-        let nums = map fst . filter (isNothing . snd) $ zip [be ..]  maybes
+        maybes <- mapM (readArray pktq) (take (fromIntegral qsize) $ map (`mod` qsize) [ buffend0 .. seqno0 ])
+        let nums = map fst . filter (isNothing . snd) $ zip [buffend0 ..]  maybes
         return (Left nums)
       else do
-        let i = i0 `mod` qsize
+        let i = seqno0 `mod` qsize
         x <- maybe retry return =<< readArray pktq i
         writeArray pktq i Nothing
         modifyTVar' seqno   succ