Replace Tornado with AnyIO

Author: davidbrochart

.github/workflows/ci.yml

@@ -85,7 +85,7 @@ jobs:
         run: |
           hatch run typing:test
           hatch run lint:style
-          pipx run interrogate -vv .
+          pipx run interrogate -vv . --fail-under 90
           pipx run doc8 --max-line-length=200
 
   check_release:

examples/embedding/inprocess_terminal.py

@@ -1,8 +1,7 @@
 """An in-process terminal example."""
 import os
-import sys
 
-import tornado
+from anyio import run
 from jupyter_console.ptshell import ZMQTerminalInteractiveShell
 
 from ipykernel.inprocess.manager import InProcessKernelManager
@@ -13,46 +12,15 @@ def print_process_id():
     print("Process ID is:", os.getpid())
 
 
-def init_asyncio_patch():
-    """set default asyncio policy to be compatible with tornado
-    Tornado 6 (at least) is not compatible with the default
-    asyncio implementation on Windows
-    Pick the older SelectorEventLoopPolicy on Windows
-    if the known-incompatible default policy is in use.
-    do this as early as possible to make it a low priority and overridable
-    ref: https://github.com/tornadoweb/tornado/issues/2608
-    FIXME: if/when tornado supports the defaults in asyncio,
-           remove and bump tornado requirement for py38
-    """
-    if (
-        sys.platform.startswith("win")
-        and sys.version_info >= (3, 8)
-        and tornado.version_info < (6, 1)
-    ):
-        import asyncio
-
-        try:
-            from asyncio import WindowsProactorEventLoopPolicy, WindowsSelectorEventLoopPolicy
-        except ImportError:
-            pass
-            # not affected
-        else:
-            if type(asyncio.get_event_loop_policy()) is WindowsProactorEventLoopPolicy:
-                # WindowsProactorEventLoopPolicy is not compatible with tornado 6
-                # fallback to the pre-3.8 default of Selector
-                asyncio.set_event_loop_policy(WindowsSelectorEventLoopPolicy())
-
-
-def main():
+async def main():
     """The main function."""
     print_process_id()
 
     # Create an in-process kernel
     # >>> print_process_id()
     # will print the same process ID as the main process
-    init_asyncio_patch()
     kernel_manager = InProcessKernelManager()
-    kernel_manager.start_kernel()
+    await kernel_manager.start_kernel()
     kernel = kernel_manager.kernel
     kernel.gui = "qt4"
     kernel.shell.push({"foo": 43, "print_process_id": print_process_id})
@@ -64,4 +32,4 @@ def main():
 
 
 if __name__ == "__main__":
-    main()
+    run(main)

ipykernel/control.py

@@ -1,7 +1,7 @@
 """A thread for a control channel."""
-from threading import Thread
+from threading import Event, Thread
 
-from tornado.ioloop import IOLoop
+from anyio import create_task_group, run, to_thread
 
 CONTROL_THREAD_NAME = "Control"
 
@@ -12,21 +12,29 @@ class ControlThread(Thread):
     def __init__(self, **kwargs):
         """Initialize the thread."""
         Thread.__init__(self, name=CONTROL_THREAD_NAME, **kwargs)
-        self.io_loop = IOLoop(make_current=False)
         self.pydev_do_not_trace = True
         self.is_pydev_daemon_thread = True
+        self.__stop = Event()
+        self._task = None
+
+    def set_task(self, task):
+        self._task = task
 
     def run(self):
         """Run the thread."""
         self.name = CONTROL_THREAD_NAME
-        try:
-            self.io_loop.start()
-        finally:
-            self.io_loop.close()
+        run(self._main)
+
+    async def _main(self):
+        async with create_task_group() as tg:
+            if self._task is not None:
+                tg.start_soon(self._task)
+            await to_thread.run_sync(self.__stop.wait)
+            tg.cancel_scope.cancel()
 
     def stop(self):
         """Stop the thread.
 
         This method is threadsafe.
         """
-        self.io_loop.add_callback(self.io_loop.stop)
+        self.__stop.set()

ipykernel/debugger.py

@@ -1,14 +1,17 @@
 """Debugger implementation for the IPython kernel."""
+from __future__ import annotations
+
 import os
 import re
 import sys
 import typing as t
+from math import inf
+from typing import Any
 
 import zmq
+from anyio import Event, create_memory_object_stream
 from IPython.core.getipython import get_ipython
 from IPython.core.inputtransformer2 import leading_empty_lines
-from tornado.locks import Event
-from tornado.queues import Queue
 from zmq.utils import jsonapi
 
 try:
@@ -116,7 +119,9 @@ def __init__(self, event_callback, log):
         self.tcp_buffer = ""
         self._reset_tcp_pos()
         self.event_callback = event_callback
-        self.message_queue: Queue[t.Any] = Queue()
+        self.message_send_stream, self.message_receive_stream = create_memory_object_stream[
+            dict[str, Any]
+        ](max_buffer_size=inf)
         self.log = log
 
     def _reset_tcp_pos(self):
@@ -135,7 +140,7 @@ def _put_message(self, raw_msg):
         else:
             self.log.debug("QUEUE - put message:")
             self.log.debug(msg)
-            self.message_queue.put_nowait(msg)
+            self.message_send_stream.send_nowait(msg)
 
     def put_tcp_frame(self, frame):
         """Put a tcp frame in the queue."""
@@ -186,25 +191,31 @@ def put_tcp_frame(self, frame):
 
     async def get_message(self):
         """Get a message from the queue."""
-        return await self.message_queue.get()
+        return await self.message_receive_stream.receive()
 
 
 class DebugpyClient:
     """A client for debugpy."""
 
-    def __init__(self, log, debugpy_stream, event_callback):
+    def __init__(self, log, debugpy_socket, event_callback):
         """Initialize the client."""
         self.log = log
-        self.debugpy_stream = debugpy_stream
+        self.debugpy_socket = debugpy_socket
         self.event_callback = event_callback
         self.message_queue = DebugpyMessageQueue(self._forward_event, self.log)
         self.debugpy_host = "127.0.0.1"
         self.debugpy_port = -1
         self.routing_id = None
         self.wait_for_attach = True
-        self.init_event = Event()
+        self._init_event = None
         self.init_event_seq = -1
 
+    @property
+    def init_event(self):
+        if self._init_event is None:
+            self._init_event = Event()
+        return self._init_event
+
     def _get_endpoint(self):
         host, port = self.get_host_port()
         return "tcp://" + host + ":" + str(port)
@@ -215,9 +226,9 @@ def _forward_event(self, msg):
             self.init_event_seq = msg["seq"]
         self.event_callback(msg)
 
-    def _send_request(self, msg):
+    async def _send_request(self, msg):
         if self.routing_id is None:
-            self.routing_id = self.debugpy_stream.socket.getsockopt(ROUTING_ID)
+            self.routing_id = self.debugpy_socket.getsockopt(ROUTING_ID)
         content = jsonapi.dumps(
             msg,
             default=json_default,
@@ -232,7 +243,7 @@ def _send_request(self, msg):
         self.log.debug("DEBUGPYCLIENT:")
         self.log.debug(self.routing_id)
         self.log.debug(buf)
-        self.debugpy_stream.send_multipart((self.routing_id, buf))
+        await self.debugpy_socket.send_multipart((self.routing_id, buf))
 
     async def _wait_for_response(self):
         # Since events are never pushed to the message_queue
@@ -250,7 +261,7 @@ async def _handle_init_sequence(self):
             "seq": int(self.init_event_seq) + 1,
             "command": "configurationDone",
         }
-        self._send_request(configurationDone)
+        await self._send_request(configurationDone)
 
         # 3]  Waits for configurationDone response
         await self._wait_for_response()
@@ -262,7 +273,7 @@ async def _handle_init_sequence(self):
     def get_host_port(self):
         """Get the host debugpy port."""
         if self.debugpy_port == -1:
-            socket = self.debugpy_stream.socket
+            socket = self.debugpy_socket
             socket.bind_to_random_port("tcp://" + self.debugpy_host)
             self.endpoint = socket.getsockopt(zmq.LAST_ENDPOINT).decode("utf-8")
             socket.unbind(self.endpoint)
@@ -272,14 +283,13 @@ def get_host_port(self):
 
     def connect_tcp_socket(self):
         """Connect to the tcp socket."""
-        self.debugpy_stream.socket.connect(self._get_endpoint())
-        self.routing_id = self.debugpy_stream.socket.getsockopt(ROUTING_ID)
+        self.debugpy_socket.connect(self._get_endpoint())
+        self.routing_id = self.debugpy_socket.getsockopt(ROUTING_ID)
 
     def disconnect_tcp_socket(self):
         """Disconnect from the tcp socket."""
-        self.debugpy_stream.socket.disconnect(self._get_endpoint())
+        self.debugpy_socket.disconnect(self._get_endpoint())
         self.routing_id = None
-        self.init_event = Event()
         self.init_event_seq = -1
         self.wait_for_attach = True
 
@@ -289,7 +299,7 @@ def receive_dap_frame(self, frame):
 
     async def send_dap_request(self, msg):
         """Send a dap request."""
-        self._send_request(msg)
+        await self._send_request(msg)
         if self.wait_for_attach and msg["command"] == "attach":
             rep = await self._handle_init_sequence()
             self.wait_for_attach = False
@@ -325,17 +335,19 @@ class Debugger:
     ]
 
     def __init__(
-        self, log, debugpy_stream, event_callback, shell_socket, session, just_my_code=True
+        self, log, debugpy_socket, event_callback, shell_socket, session, just_my_code=True
     ):
         """Initialize the debugger."""
         self.log = log
-        self.debugpy_client = DebugpyClient(log, debugpy_stream, self._handle_event)
+        self.debugpy_client = DebugpyClient(log, debugpy_socket, self._handle_event)
         self.shell_socket = shell_socket
         self.session = session
         self.is_started = False
         self.event_callback = event_callback
         self.just_my_code = just_my_code
-        self.stopped_queue: Queue[t.Any] = Queue()
+        self.stopped_send_stream, self.stopped_receive_stream = create_memory_object_stream[
+            dict[str, Any]
+        ](max_buffer_size=inf)
 
         self.started_debug_handlers = {}
         for msg_type in Debugger.started_debug_msg_types:
@@ -360,7 +372,7 @@ def __init__(
     def _handle_event(self, msg):
         if msg["event"] == "stopped":
             if msg["body"]["allThreadsStopped"]:
-                self.stopped_queue.put_nowait(msg)
+                self.stopped_send_stream.send_nowait(msg)
                 # Do not forward the event now, will be done in the handle_stopped_event
                 return
             else:
@@ -400,7 +412,7 @@ async def handle_stopped_event(self):
         """Handle a stopped event."""
         # Wait for a stopped event message in the stopped queue
         # This message is used for triggering the 'threads' request
-        event = await self.stopped_queue.get()
+        event = await self.stopped_receive_stream.receive()
         req = {"seq": event["seq"] + 1, "type": "request", "command": "threads"}
         rep = await self._forward_message(req)
         for thread in rep["body"]["threads"]:
@@ -412,7 +424,7 @@ async def handle_stopped_event(self):
     def tcp_client(self):
         return self.debugpy_client
 
-    def start(self):
+    async def start(self):
         """Start the debugger."""
         if not self.debugpy_initialized:
             tmp_dir = get_tmp_directory()
@@ -430,7 +442,12 @@ def start(self):
                 (self.shell_socket.getsockopt(ROUTING_ID)),
             )
 
-            ident, msg = self.session.recv(self.shell_socket, mode=0)
+            msg = await self.shell_socket.recv_multipart()
+            ident, msg = self.session.feed_identities(msg, copy=True)
+            try:
+                msg = self.session.deserialize(msg, content=True, copy=True)
+            except Exception:
+                self.log.error("Invalid message", exc_info=True)
             self.debugpy_initialized = msg["content"]["status"] == "ok"
 
         # Don't remove leading empty lines when debugging so the breakpoints are correctly positioned
@@ -719,7 +736,7 @@ async def process_request(self, message):
             if self.is_started:
                 self.log.info("The debugger has already started")
             else:
-                self.is_started = self.start()
+                self.is_started = await self.start()
                 if self.is_started:
                     self.log.info("The debugger has started")
                 else:

ipykernel/eventloops.py

@@ -388,13 +388,12 @@ def loop_asyncio(kernel):
     loop._should_close = False  # type:ignore[attr-defined]
 
     # pause eventloop when there's an event on a zmq socket
-    def process_stream_events(stream):
+    def process_stream_events(socket):
         """fall back to main loop when there's a socket event"""
-        if stream.flush(limit=1):
-            loop.stop()
+        loop.stop()
 
-    notifier = partial(process_stream_events, kernel.shell_stream)
-    loop.add_reader(kernel.shell_stream.getsockopt(zmq.FD), notifier)
+    notifier = partial(process_stream_events, kernel.shell_socket)
+    loop.add_reader(kernel.shell_socket.getsockopt(zmq.FD), notifier)
     loop.call_soon(notifier)
 
     while True:

ipykernel/inprocess/blocking.py

@@ -80,10 +80,10 @@ class BlockingInProcessKernelClient(InProcessKernelClient):
     iopub_channel_class = Type(BlockingInProcessChannel)  # type:ignore[arg-type]
     stdin_channel_class = Type(BlockingInProcessStdInChannel)  # type:ignore[arg-type]
 
-    def wait_for_ready(self):
+    async def wait_for_ready(self):
         """Wait for kernel info reply on shell channel."""
         while True:
-            self.kernel_info()
+            await self.kernel_info()
             try:
                 msg = self.shell_channel.get_msg(block=True, timeout=1)
             except Empty:
@@ -103,6 +103,5 @@ def wait_for_ready(self):
         while True:
             try:
                 msg = self.iopub_channel.get_msg(block=True, timeout=0.2)
-                print(msg["msg_type"])
             except Empty:
                 break