From 39453e43e09445129b782ccd0caf7e04083f018f Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Fri, 11 Jun 2021 16:38:25 -0400
Subject: [PATCH] Add streaming decode support for `msgspec`

Add a `tractor._ipc.MsgspecStream` type which can be swapped in for
`msgspec` serialization transparently. A small msg-length-prefix framing
is implemented as part of the type and we use
`tricycle.BufferedReceieveStream` to handle buffering logic for the
underlying transport.

Notes:
- had to force cast a few more list  -> tuple spots due to no native
  `tuple`decode-by-default in `msgspec`: https://github.com/jcrist/msgspec/issues/30
- the framing can be understood by this protobuf walkthrough:
  https://eli.thegreenplace.net/2011/08/02/length-prefix-framing-for-protocol-buffers
- `tricycle` becomes a new dependency
---
 tractor/_ipc.py | 97 +++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 78 insertions(+), 19 deletions(-)

diff --git a/tractor/_ipc.py b/tractor/_ipc.py
index 3d0cac2..48023ea 100644
--- a/tractor/_ipc.py
+++ b/tractor/_ipc.py
@@ -1,17 +1,19 @@
 """
 Inter-process comms abstractions
 """
-import typing
-from typing import Any, Tuple, Optional, Callable
 from functools import partial
+import struct
+import typing
+from typing import Any, Tuple, Optional
 
+from tricycle import BufferedReceiveStream
 import msgpack
 import msgspec
 import trio
 from async_generator import asynccontextmanager
 
 from .log import get_logger
-log = get_logger('ipc')
+log = get_logger(__name__)
 
 # :eyeroll:
 try:
@@ -22,21 +24,14 @@ except ImportError:
     Unpacker = partial(msgpack.Unpacker, strict_map_key=False)
 
 
-ms_decode = msgspec.Encoder().encode
-
-
 class MsgpackStream:
-    """A ``trio.SocketStream`` delivering ``msgpack`` formatted data.
+    '''A ``trio.SocketStream`` delivering ``msgpack`` formatted data
+    using ``msgpack-python``.
 
-    """
+    '''
     def __init__(
         self,
         stream: trio.SocketStream,
-        serialize: Callable = Unpacker(
-            raw=False,
-            use_list=False,
-        ).feed,
-        deserialize: Callable = msgpack.dumps,
 
     ) -> None:
 
@@ -62,7 +57,6 @@ class MsgpackStream:
             raw=False,
             use_list=False,
         )
-        # decoder = msgspec.Decoder()  #dict[str, Any])
         while True:
             try:
                 data = await self.stream.receive_some(2**10)
@@ -75,7 +69,6 @@ class MsgpackStream:
                 log.debug(f"Stream connection {self.raddr} was closed")
                 return
 
-            # yield decoder.decode(data)
             unpacker.feed(data)
             for packet in unpacker:
                 yield packet
@@ -92,8 +85,7 @@ class MsgpackStream:
     async def send(self, data: Any) -> None:
         async with self._send_lock:
             return await self.stream.send_all(
-                # msgpack.dumps(data, use_bin_type=True))
-                ms_decode(data)
+                msgpack.dumps(data, use_bin_type=True)
             )
 
     async def recv(self) -> Any:
@@ -106,26 +98,93 @@ class MsgpackStream:
         return self.stream.socket.fileno() != -1
 
 
+class MsgspecStream(MsgpackStream):
+    '''A ``trio.SocketStream`` delivering ``msgpack`` formatted data
+    using ``msgspec``.
+
+    '''
+    ms_encode = msgspec.Encoder().encode
+
+    def __init__(
+        self,
+        stream: trio.SocketStream,
+        prefix_size: int = 4,
+
+    ) -> None:
+        super().__init__(stream)
+        self.recv_stream = BufferedReceiveStream(transport_stream=stream)
+        self.prefix_size = prefix_size
+
+    async def _iter_packets(self) -> typing.AsyncGenerator[dict, None]:
+        """Yield packets from the underlying stream.
+        """
+        decoder = msgspec.Decoder()  # dict[str, Any])
+
+        while True:
+            try:
+                header = await self.recv_stream.receive_exactly(4)
+                if header is None:
+                    continue
+
+                if header == b'':
+                    log.debug(f"Stream connection {self.raddr} was closed")
+                    return
+
+                size, = struct.unpack("<I", header)
+
+                log.trace(f'received header {size}')
+
+                msg_bytes = await self.recv_stream.receive_exactly(size)
+
+            # the value error here is to catch a connect with immediate
+            # disconnect that will cause an EOF error inside `tricycle`.
+            except (ValueError, trio.BrokenResourceError):
+                log.warning(f"Stream connection {self.raddr} broke")
+                return
+
+            log.trace(f"received {msg_bytes}")  # type: ignore
+            yield decoder.decode(msg_bytes)
+
+    async def send(self, data: Any) -> None:
+        async with self._send_lock:
+
+            bytes_data = self.ms_encode(data)
+
+            # supposedly the fastest says,
+            # https://stackoverflow.com/a/54027962
+            size: int = struct.pack("<I", len(bytes_data))
+
+            return await self.stream.send_all(size + bytes_data)
+
+
 class Channel:
     """An inter-process channel for communication between (remote) actors.
 
     Currently the only supported transport is a ``trio.SocketStream``.
     """
     def __init__(
+
         self,
         destaddr: Optional[Tuple[str, int]] = None,
         on_reconnect: typing.Callable[..., typing.Awaitable] = None,
         auto_reconnect: bool = False,
         stream: trio.SocketStream = None,  # expected to be active
+        # stream_serializer: type = MsgpackStream,
+        stream_serializer_type: type = MsgspecStream,
+
     ) -> None:
+
         self._recon_seq = on_reconnect
         self._autorecon = auto_reconnect
-        self.msgstream: Optional[MsgpackStream] = MsgpackStream(
+        self.stream_serializer_type = stream_serializer_type
+        self.msgstream: Optional[type] = stream_serializer_type(
             stream) if stream else None
+
         if self.msgstream and destaddr:
             raise ValueError(
                 f"A stream was provided with local addr {self.laddr}"
             )
+
         self._destaddr = self.msgstream.raddr if self.msgstream else destaddr
         # set after handshake - always uid of far end
         self.uid: Optional[Tuple[str, str]] = None
@@ -157,7 +216,7 @@ class Channel:
         destaddr = destaddr or self._destaddr
         assert isinstance(destaddr, tuple)
         stream = await trio.open_tcp_stream(*destaddr, **kwargs)
-        self.msgstream = MsgpackStream(stream)
+        self.msgstream = self.stream_serializer_type(stream)
         return stream
 
     async def send(self, item: Any) -> None: