From 8d9abc1df036a8184bc2fd88ddf6f1d621e7e4c1 Mon Sep 17 00:00:00 2001
From: James Crayne <jim.crayne@gmail.com>
Date: Sun, 19 Nov 2017 22:52:07 +0000
Subject: Outgoing queue and related

---
 src/Data/PacketQueue.hs | 93 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 92 insertions(+), 1 deletion(-)

(limited to 'src/Data/PacketQueue.hs')

diff --git a/src/Data/PacketQueue.hs b/src/Data/PacketQueue.hs
index b349bf4b..927d6c53 100644
--- a/src/Data/PacketQueue.hs
+++ b/src/Data/PacketQueue.hs
@@ -3,12 +3,19 @@
 -- be stored out of order, but from which they are extracted in the proper
 -- sequence.
 {-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE FlexibleContexts #-}
 module Data.PacketQueue
     ( PacketQueue
     , new
     , dequeue
     , enqueue
     , observeOutOfBand
+    , PacketOutQueue
+    , newOutGoing
+    , tryAppendQueueOutgoing
+    , dequeueOutgoing
+    , mapOutGoing
+    , OutGoingResult(..)
     ) where
 
 import Control.Concurrent.STM
@@ -21,7 +28,7 @@ data PacketQueue a = PacketQueue
     { pktq    :: TArray Word32 (Maybe a)
     , seqno   :: TVar Word32
     , qsize   :: Word32
-    , buffend :: TVar Word32
+    , buffend :: TVar Word32 -- on incoming, highest packet number handled + 1
     }
 
 -- | Create a new PacketQueue.
@@ -77,3 +84,87 @@ enqueue PacketQueue{ pktq, seqno, qsize, buffend } no x = do
 
 -- lookup :: PacketQueue a -> Word32 -> STM (Maybe a)
 -- lookup PacketQueue{ pktq, seqno, qsize } no = _todo
+
+-----------------------------------------------------
+-- * PacketOutQueue
+--
+
+data PacketOutQueue extra msg toWire fromWire = PacketOutQueue
+    { pktoInPQ   :: PacketQueue fromWire -- ^ reference to the incoming 'PacketQueue'
+    , pktoOutPQ  :: PacketQueue (Word32,toWire)
+    , pktoPacketNo :: TVar Word32
+    , pktoToWireIO :: IO (STM extra)
+    , pktoToWire :: STM extra
+                 -> Word32{-packet number we expect to recieve-}
+                 -> Word32{- buffer_end -}
+                 -> Word32{- packet number -}
+                 -> msg
+                 -> STM (Maybe (toWire,Word32{-next packet no-}))
+    }
+
+mapOutGoing :: ((Word32,towire) -> Maybe (Word32,towire)) -> PacketOutQueue extra msg towire fromwire -> STM ()
+mapOutGoing f q@(PacketOutQueue { pktoOutPQ=PacketQueue{ pktq } }) = do
+    (z,n) <- getBounds pktq
+    let ff i = do
+        e <- readArray pktq i
+        writeArray pktq i (e>>=f)
+    mapM_ ff [z .. n]
+
+newOutGoing :: PacketQueue fromwire
+                      -- ^ Incoming queue
+            -> (STM io -> Word32 {-packet number we expect to recieve-} -> Word32{-buffer_end-} -> Word32{-packet number-} -> msg -> STM (Maybe (wire,Word32{-next packet no-})))
+                      -- ^ toWire callback
+            -> IO (STM io)
+                      -- ^ io action to get extra parameter
+            -> Word32 -- ^ packet number of first outgoing packet
+            -> Word32 -- ^ Capacity of queue.
+            -> Word32 -- ^ Initial sequence number.
+            -> STM (PacketOutQueue io msg wire fromwire)
+newOutGoing inq towire toWireIO num capacity seqstart = do
+    outq <- new capacity seqstart
+    numVar <- newTVar num
+    return $ PacketOutQueue
+                { pktoInPQ = inq
+                , pktoOutPQ = outq
+                , pktoPacketNo = numVar
+                , pktoToWireIO = toWireIO
+                , pktoToWire = towire
+                }
+
+data OutGoingResult = OGSuccess | OGFull | OGEncodeFail
+    deriving (Eq,Show)
+
+-- | Convert a message to packet format and append it to the front of a queue
+--   used for outgoing messages. (Note that ‘front‛ usually means the higher
+--   index in this implementation.)
+tryAppendQueueOutgoing :: STM extra -> PacketOutQueue extra msg wire fromwire -> msg -> STM OutGoingResult
+tryAppendQueueOutgoing getExtra q@(PacketOutQueue { pktoInPQ, pktoOutPQ, pktoPacketNo, pktoToWireIO, pktoToWire }) msg = do
+    be <- readTVar (buffend pktoOutPQ)
+    let i = be `mod` (qsize pktoOutPQ)
+    mbPkt <- readArray (pktq pktoOutPQ) i
+    pktno <- readTVar pktoPacketNo
+    nextno <- readTVar (seqno pktoInPQ)
+    mbWire <- pktoToWire getExtra nextno be pktno msg
+    case mbWire of
+        Just (pkt,pktno')
+            -> case mbPkt of
+                    -- slot is free, insert element
+                    Nothing -> do
+                        modifyTVar' (buffend pktoOutPQ) (+1)
+                        writeTVar pktoPacketNo $! pktno'
+                        writeArray (pktq pktoOutPQ) i (Just (pktno,pkt))
+                        return OGSuccess
+                    -- queue is full, block until its not
+                    _       -> return OGFull
+        -- don't know how to send this message
+        Nothing -> return OGEncodeFail
+
+dequeueOutgoing :: PacketOutQueue extra msg wire fromwire -> STM (Word32,wire)
+dequeueOutgoing (PacketOutQueue {pktoOutPQ=PacketQueue { pktq, seqno, qsize }}) = do
+    i0 <- readTVar seqno
+    let i = i0 `mod` qsize
+    x <- maybe retry return =<< readArray pktq i
+    -- writeArray pktq i Nothing -- not cleaning
+    modifyTVar' seqno   succ
+    return x
+
-- 
cgit v1.2.3