From c3a66fe663254856e441ef320facac4f4956594a Mon Sep 17 00:00:00 2001
From: Divam <dfordivam@gmail.com>
Date: Thu, 16 Jan 2020 11:47:24 +0900
Subject: [PATCH 1/2] wip: read one message, starting with size

---
 src/Language/Javascript/JSaddle/Wasm.hs | 38 +++++++++++++++----------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/src/Language/Javascript/JSaddle/Wasm.hs b/src/Language/Javascript/JSaddle/Wasm.hs
index 0fe316f..fa504b8 100644
--- a/src/Language/Javascript/JSaddle/Wasm.hs
+++ b/src/Language/Javascript/JSaddle/Wasm.hs
@@ -54,11 +54,15 @@ run _ entryPoint = do
     receiveDataMessage = loop
       where
         loop = do
-          threadDelay (100)
-          try (BSIO.hGetLine jsInOut)
+          threadDelay 1
+          try (BSIO.hGetNonBlocking jsInOut 4)
             >>= \case
               (Left (ex :: IOException)) -> loop
-              (Right v) -> return $ BS.fromStrict v
+              (Right v)
+                | BSIO.null v -> loop
+                | otherwise -> do
+                  let size = Binary.decode (BS.fromStrict v) :: Word32
+                  BS.fromStrict <$> BSIO.hGetNonBlocking jsInOut (fromIntegral size)
 
     -- When to exit? never?
     waitTillClosed = forever $ do
@@ -69,20 +73,24 @@ run _ entryPoint = do
   (processResult, _, start) <-
     runJavaScript sendBatch entryPoint
   forkIO . forever $ do
-    msgs <- receiveDataMessage
-    processIncomingMsgs processResult msgs
+    thisMsg <- receiveDataMessage
+    case decode thisMsg of
+      Nothing -> error $ "jsaddle Results decode failed : " <> show thisMsg
+      Just r  -> processResult r
 
   start
   waitTillClosed
 
 processIncomingMsgs :: (Results -> IO ()) -> ByteString -> IO ()
-processIncomingMsgs cont msgs = do
-  let
-    size = Binary.decode (BS.take 4 msgs) :: Word32
-    (thisMsg, rest) = BS.splitAt (fromIntegral $ 4 + size) msgs
-  case decode (BS.drop 4 thisMsg) of
-    Nothing -> error $ "jsaddle Results decode failed : " <> show thisMsg
-    Just r  -> cont r
-  case BS.length rest of
-    0 -> return ()
-    _ -> processIncomingMsgs cont rest
+processIncomingMsgs cont msgs = if (BS.length msgs < 5)
+  then error $ "no data loop: " <> show msgs
+  else do
+    let
+      size = Binary.decode (BS.take 4 msgs) :: Word32
+      (thisMsg, rest) = BS.splitAt (fromIntegral $ 4 + size) msgs
+    case decode (BS.drop 4 thisMsg) of
+      Nothing -> error $ "jsaddle Results decode failed : " <> show thisMsg
+      Just r  -> cont r
+    case BS.length rest of
+      0 -> return ()
+      _ -> processIncomingMsgs cont rest

From 01334b7fd88e62489557be77e9bad832b8243b4a Mon Sep 17 00:00:00 2001
From: Divam <dfordivam@gmail.com>
Date: Thu, 16 Jan 2020 14:05:57 +0900
Subject: [PATCH 2/2] Process messages in chunks

---
 src/Language/Javascript/JSaddle/Wasm.hs | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/Language/Javascript/JSaddle/Wasm.hs b/src/Language/Javascript/JSaddle/Wasm.hs
index fa504b8..e43cf92 100644
--- a/src/Language/Javascript/JSaddle/Wasm.hs
+++ b/src/Language/Javascript/JSaddle/Wasm.hs
@@ -61,7 +61,8 @@ run _ entryPoint = do
               (Right v)
                 | BSIO.null v -> loop
                 | otherwise -> do
-                  let size = Binary.decode (BS.fromStrict v) :: Word32
+                  -- Somehow we get this size in reverse!!
+                  let size = Binary.decode (BS.reverse $ BS.fromStrict v) :: Word32
                   BS.fromStrict <$> BSIO.hGetNonBlocking jsInOut (fromIntegral size)
 
     -- When to exit? never?
@@ -73,17 +74,15 @@ run _ entryPoint = do
   (processResult, _, start) <-
     runJavaScript sendBatch entryPoint
   forkIO . forever $ do
-    thisMsg <- receiveDataMessage
-    case decode thisMsg of
-      Nothing -> error $ "jsaddle Results decode failed : " <> show thisMsg
-      Just r  -> processResult r
+    msgs <- receiveDataMessage
+    processIncomingMsgs processResult msgs
 
   start
   waitTillClosed
 
 processIncomingMsgs :: (Results -> IO ()) -> ByteString -> IO ()
 processIncomingMsgs cont msgs = if (BS.length msgs < 5)
-  then error $ "no data loop: " <> show msgs
+  then error $ "processIncomingMsgs: no more data while looping: " <> show msgs
   else do
     let
       size = Binary.decode (BS.take 4 msgs) :: Word32