SMP protocol: optimize batching transactions, remove Builder (#961)

* remove Builder

* fewer chunks

* remove lazy bytestrings

* optimize

* pad

src/Simplex/FileTransfer/Protocol.hs

@@ -24,7 +24,6 @@ import Data.List.NonEmpty (NonEmpty (..))
 import Data.Maybe (isNothing)
 import Data.Type.Equality
 import Data.Word (Word32)
-import Simplex.Messaging.Builder (Builder)
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
@@ -49,8 +48,7 @@ import Simplex.Messaging.Protocol
     encodeTransmission,
     messageTagP,
     tDecodeParseValidate,
-    tEncode,
-    tEncodeBatch,
+    tEncodeBatch1,
     tParse,
   )
 import Simplex.Messaging.Transport (SessionId, TransportError (..))
@@ -395,7 +393,7 @@ checkParty' c = case testEquality (sFileParty @p) (sFileParty @p') of
   Just Refl -> Just c
   _ -> Nothing
 
-xftpEncodeTransmission :: ProtocolEncoding e c => SessionId -> Maybe C.APrivateSignKey -> Transmission c -> Either TransportError Builder
+xftpEncodeTransmission :: ProtocolEncoding e c => SessionId -> Maybe C.APrivateSignKey -> Transmission c -> Either TransportError ByteString
 xftpEncodeTransmission sessionId pKey (corrId, fId, msg) = do
   let t = encodeTransmission currentXFTPVersion sessionId (corrId, fId, msg)
   xftpEncodeBatch1 $ signTransmission t
@@ -404,10 +402,8 @@ xftpEncodeTransmission sessionId pKey (corrId, fId, msg) = do
     signTransmission t = ((`C.sign` t) <$> pKey, t)
 
 -- this function uses batch syntax but puts only one transmission in the batch
-xftpEncodeBatch1 :: (Maybe C.ASignature, ByteString) -> Either TransportError Builder
-xftpEncodeBatch1 (sig, t) =
-  let t' = tEncodeBatch 1 . encodeLarge $ tEncode (sig, t)
-   in first (const TELargeMsg) $ C.pad' t' xftpBlockSize
+xftpEncodeBatch1 :: SentRawTransmission -> Either TransportError ByteString
+xftpEncodeBatch1 t = first (const TELargeMsg) $ C.pad (tEncodeBatch1 t) xftpBlockSize
 
 xftpDecodeTransmission :: ProtocolEncoding e c => SessionId -> ByteString -> Either XFTPErrorType (SignedTransmission e c)
 xftpDecodeTransmission sessionId t = do