"""Communication primitives for GeoGebra frontend↔kernel messaging.
This module implements a dual-channel communication layer combining
IPython Comm with an out-of-band socket (Unix domain socket or WebSocket)
to ensure reliable message delivery while notebook cells execute.
"""
import uuid
import json
import queue
import concurrent.futures
import asyncio
import threading
import tempfile
import time
from websockets.asyncio.server import unix_serve, serve
import os
from IPython import get_ipython
from .errors import GeoGebraAppletError
# Optional ipywidgets import for DOMWidget-based comm bridge
try:
import ipywidgets as _ipywidgets
_WIDGETS_AVAILABLE = True
except Exception:
_ipywidgets = None
_WIDGETS_AVAILABLE = False
[docs]
class ggb_comm:
"""Dual-channel communication layer for kernel↔widget messaging.
Implements a combination of IPython Comm (primary) and out-of-band socket
(Unix domain socket on POSIX, TCP WebSocket on Windows) to enable message
delivery during cell execution when IPython Comm is blocked.
IPython Comm cannot receive messages while a notebook cell is executing,
which breaks interactive workflows. The out-of-band socket solves this by
providing a secondary channel for GeoGebra responses.
Architecture:
- IPython Comm: Command dispatch, event notifications, heartbeat
- Out-of-band socket: Response delivery during cell execution
Comm target is fixed at 'jupyter.ggblab' because multiplexing via multiple
targets would not solve the IPython Comm receive limitation. The
dotted name follows the ipywidgets-style naming convention and is also
used by `load_ipython_extension` to register the handler at runtime.
Attributes:
target_comm: IPython Comm object
target_name (str): Comm target name ('ggblab-comm')
server_handle: WebSocket server handle
server_thread: Background thread running the socket server
clients (set): Currently connected WebSocket clients
socketPath (str): Unix domain socket path (POSIX)
wsPort (int): TCP port number (Windows)
pending_futures (dict): Mapping of message-id to Future for awaiting responses
recv_events (queue.Queue): Event queue for frontend notifications
Future improvement:
Consider integrating the out-of-band server with Jupyter's
Tornado/ioloop to avoid cross-thread asyncio interactions. This
would simplify event-loop boundaries but has non-trivial
implementation cost, so it's deferred for future work.
"""
# [Frontent to kernel callback - JupyterLab - Jupyter Community Forum]
# (https://discourse.jupyter.org/t/frontent-to-kernel-callback/1666)
recv_msgs = {}
# pending_futures maps message-id -> concurrent.futures.Future
pending_futures = {}
recv_events = queue.Queue()
logs = []
# Shared object state published by incoming `object_update` events.
# This is a class-level dict intended for cross-instance/global access.
shared_objects = {}
thread = None
thread_lock = threading.Lock()
mid = None
# target_comm = None
def __init__(self):
"""Initialize communication state and defaults."""
self.target_comm = None
self.target_name = 'jupyter.ggblab'
self.server_handle = None
self.server_thread = None
self.clients = set()
self.socketPath = None
self.wsPort = 0
# Event to signal the background server thread to stop
self._stop_event = threading.Event()
# counters for noisy connect/disconnect events; used to aggregate logs
self._client_connect_count = 0
self._client_disconnect_count = 0
self._last_client_log_time = 0.0
# applet_started removed; rely on out-of-band responses (pending_futures)
# NOTE: Originally we planned to use an explicit 'start' handshake so that
# `ggbapplet.init()` could be executed in the same notebook cell that
# starts the frontend. In practice, IPython Comm target registration and
# handler installation are not reliably completed until the cell's
# execution finishes, so messages emitted within the same cell may not
# be received. Because of this timing constraint the 'applet_start'
# handshake was left pending and removed here to avoid brittle behavior.
# Per-instance mapping from message id to Future
self.pending_futures = {}
# Optional ipywidgets bridge widget whose comm can be reused
self.widget_bridge = None
# Prefer to register the IPython Comm target by default so the
# frontend can open a kernel-level Comm for command/response.
# Older behaviour allowed opting out; keep the flag for backwards
# compatibility but default to True which is the expected path now.
self.use_ipython_comm = True
# Feature flag: enable creation of an ipywidgets-based bridge
# when `use_ipython_comm` is False. Keep disabled by default to
# avoid creating transient kernel-side Comms during init.
self.enable_widget_bridge = False
# Debug flag: when False, suppress non-actionable diagnostic log entries
self.debug = False
# oob websocket (unix_domain socket in posix)
[docs]
def start(self):
"""Start the out-of-band socket server in a background thread.
Creates a Unix domain socket (POSIX) or TCP WebSocket server (Windows)
and runs it in a daemon thread. The server listens for GeoGebra responses.
"""
# Ensure any previous stop event is cleared and start server thread
try:
self._stop_event.clear()
except Exception:
self._stop_event = threading.Event()
self.server_thread = threading.Thread(target=lambda: asyncio.run(self.server()), daemon=True)
self.server_thread.start()
[docs]
def stop(self):
"""Stop the out-of-band socket server."""
try:
# Signal the server to stop
self._stop_event.set()
except Exception:
pass
try:
# Allow the server coroutine to exit its context and the thread to join
if self.server_thread is not None:
self.server_thread.join(timeout=1.0)
except Exception:
pass
try:
if self.server_handle is not None:
# best-effort close; actual closure happens when server coroutine exits
close = getattr(self.server_handle, 'close', None)
if callable(close):
close()
except Exception:
pass
[docs]
async def server(self):
"""Run the out-of-band socket server.
Uses a Unix domain socket on POSIX systems and a TCP WebSocket otherwise.
"""
loop = asyncio.get_running_loop()
if os.name in [ 'posix' ]:
_fd, self.socketPath = tempfile.mkstemp(prefix="/tmp/ggb_")
os.close(_fd)
os.remove(self.socketPath)
async with unix_serve(self.client_handle, path=self.socketPath) as self.server_handle:
# Wait until stop_event is set in another thread
await loop.run_in_executor(None, self._stop_event.wait)
else:
async with serve(self.client_handle, "localhost", 0) as self.server_handle:
with self.thread_lock:
self.wsPort = self.server_handle.sockets[0].getsockname()[1]
try:
self.logs.append(f"WebSocket server started at ws://localhost:{self.wsPort}")
except Exception:
pass
# Wait until stop_event is set in another thread
await loop.run_in_executor(None, self._stop_event.wait)
[docs]
async def client_handle(self, client_id):
"""Handle messages from a connected websocket client.
Routes command responses into `pending_futures` and event messages into `recv_events`.
"""
with self.thread_lock:
self.clients.add(client_id)
self._client_connect_count += 1
# rate-limit detailed connect logs to once every 5 seconds
try:
now = time.time()
if now - self._last_client_log_time > 5.0:
self.logs.append(
f"Clients connected: {len(self.clients)} (connects+={self._client_connect_count}, disconnects+={self._client_disconnect_count})"
)
self._client_connect_count = 0
self._client_disconnect_count = 0
self._last_client_log_time = now
except Exception:
pass
try:
async for msg in client_id:
# _data = ast.literal_eval(msg)
_data = json.loads(msg)
# If this is an `object_update` event, update the shared_objects
# class-level mapping so other consumers can read the latest
# object values. Payloads may be a single pair [name, value]
# or a list of pairs.
try:
if isinstance(_data, dict) and _data.get('type') == 'object_update':
payload = _data.get('payload')
try:
with self.thread_lock:
cls = self.__class__
# list of pairs [[name, value], ...]
if isinstance(payload, list) and payload and isinstance(payload[0], list):
for pair in payload:
if isinstance(pair, list) and len(pair) >= 2:
name = pair[0]
value = pair[1]
try:
cls.shared_objects[name] = value
except Exception:
pass
# single pair [name, value]
elif isinstance(payload, list) and len(payload) >= 2 and not any(isinstance(i, list) for i in payload):
name = payload[0]
value = payload[1]
try:
cls.shared_objects[name] = value
except Exception:
pass
# payload may be a dict {name: value, ...}
elif isinstance(payload, dict):
for k, v in payload.items():
try:
cls.shared_objects[k] = v
except Exception:
pass
except Exception:
try:
with self.thread_lock:
self.logs.append('Failed to process object_update payload')
except Exception:
pass
except Exception:
pass
_id = _data.get('id')
# self.logs.append(f"Received message from client: {_id}")
# Route event-type messages to recv_events queue
# Messages with 'id' are command responses; messages without 'id' are events.
# This enables:
# - Real-time error capture during cell execution
# - Dynamic scope learning from Applet error events
# - Cross-domain error pattern analysis
if _id:
# Response message: fulfill any waiting Future for this id
with self.thread_lock:
fut = self.pending_futures.pop(_id, None)
if fut:
try:
# Safely set the result on the waiting Future.
# Handle both asyncio.Future (must be set on its loop)
# and concurrent.futures.Future (thread-safe set_result).
import asyncio as _asyncio
try:
is_asyncio = isinstance(fut, _asyncio.Future)
except Exception:
is_asyncio = False
if is_asyncio:
# Try to obtain the loop associated with the future.
loop = None
try:
get_loop = getattr(fut, 'get_loop', None)
if callable(get_loop):
loop = get_loop()
except Exception:
loop = getattr(fut, '_loop', None)
# If the loop is running, schedule thread-safe set_result.
if loop is not None and getattr(loop, 'is_running', lambda: False)():
loop.call_soon_threadsafe(fut.set_result, _data['payload'])
else:
# Fallback: set directly (may raise if not allowed).
fut.set_result(_data['payload'])
else:
# concurrent.futures.Future is safe to set from other threads
fut.set_result(_data['payload'])
except Exception:
# ignore set_result errors but record for diagnostics when debug
try:
if getattr(self, 'debug', False):
with self.thread_lock:
self.logs.append(f"Error setting result for id {_id}")
except Exception:
pass
else:
# No future waiting; quietly ignore unless debugging
try:
if getattr(self, 'debug', False):
with self.thread_lock:
self.logs.append(f"Unexpected response for id {_id}")
except Exception:
pass
else:
# Event message: queue for event processing
# Error handling is deferred to send_recv() for proper exception propagation
self.recv_events.put(_data)
# yield to the event loop so other coroutines can make progress
await asyncio.sleep(0)
except Exception as e:
# record connection errors for diagnostics instead of silently passing
try:
with self.thread_lock:
# record connection errors but avoid spamming; use same rate-limit
now = time.time()
if now - self._last_client_log_time > 5.0:
# Connection errors are notable; always record
self.logs.append(f"Connection error: {e}")
self._last_client_log_time = now
except Exception:
pass
# self.logs.append(f"Connection closed: {e}")
finally:
with self.thread_lock:
try:
self.clients.remove(client_id)
except Exception:
pass
self._client_disconnect_count += 1
try:
now = time.time()
if now - self._last_client_log_time > 5.0:
self.logs.append(
f"Clients connected: {len(self.clients)} (connects+={self._client_connect_count}, disconnects+={self._client_disconnect_count})"
)
self._client_connect_count = 0
self._client_disconnect_count = 0
self._last_client_log_time = now
except Exception:
pass
# comm
[docs]
def register_target(self):
"""Register the IPython Comm target for frontend messages.
Note: IPython Comm registration is disabled by default (see
`self.use_ipython_comm`). Callers may enable it by setting that
attribute to True before calling this method.
"""
if not getattr(self, 'use_ipython_comm', False):
# If widget-bridge creation is disabled, return early.
if not getattr(self, 'enable_widget_bridge', False):
try:
if getattr(self, 'debug', False):
with self.thread_lock:
self.logs.append('IPython Comm registration skipped (use_ipython_comm=False)')
except Exception:
pass
return
# Otherwise attempt to create a minimal ipywidgets bridge (best-effort).
if not _WIDGETS_AVAILABLE:
try:
if getattr(self, 'debug', False):
with self.thread_lock:
self.logs.append('ipywidgets not available; IPython Comm registration skipped')
except Exception:
pass
return
try:
# create or reuse bridge
if self.widget_bridge is None:
wb = _ipywidgets.Widget()
self.widget_bridge = wb
# route widget messages to handle_recv
def _on_msg(widget, content, buffers):
try:
# normalize into previous message shape
msg = {'content': {'data': content}}
self.handle_recv(msg)
except Exception:
try:
with self.thread_lock:
self.logs.append('Error handling widget bridge message')
except Exception:
pass
try:
self.widget_bridge.on_msg(_on_msg)
except Exception:
# Older ipywidgets may use different signature; ignore if not supported
pass
try:
if getattr(self, 'debug', False):
with self.thread_lock:
self.logs.append('Using ipywidgets bridge for comms')
except Exception:
pass
except Exception:
try:
if getattr(self, 'debug', False):
with self.thread_lock:
self.logs.append('Failed to create ipywidgets bridge')
except Exception:
pass
return
# If explicitly requested, perform IPython Comm registration (best-effort)
try:
get_ipython().kernel.comm_manager.register_target(
self.target_name,
self.register_target_cb)
except Exception:
try:
with self.thread_lock:
self.logs.append('Failed to register IPython Comm target')
except Exception:
pass
# Ensure we have a post-execute hook to flush any queued events
try:
self.register_post_execute()
except Exception:
pass
[docs]
def register_target_cb(self, comm, msg):
"""Register the IPython Comm connection callback and install message handlers."""
# IPython Comm is not thread-aware; protect assignment anyway
with self.thread_lock:
self.target_comm = comm
try:
if getattr(self, 'debug', False):
self.logs.append(f"register_target_cb: {self.target_comm}")
except Exception:
pass
@comm.on_msg
def _recv(msg):
self.handle_recv(msg)
@comm.on_close
def _close():
self.target_comm = None
[docs]
def unregister_target_cb(self):
"""Unregister and close the IPython Comm connection."""
with self.thread_lock:
try:
if self.target_comm:
self.target_comm.close()
except Exception:
pass
self.target_comm = None
def _post_execute_handler(self, *args, **kwargs):
"""Post-execute handler to flush queued recv events.
Some frontends (and ipywidgets-based backends) rely on processing
queued events after a cell finishes execution. Registering a
`post_execute` hook helps ensure any events that arrived while a
cell was executing are drained and surfaced to diagnostics.
"""
try:
drained = 0
while True:
try:
ev = self.recv_events.get_nowait()
except queue.Empty:
break
drained += 1
try:
with self.thread_lock:
# Keep a compact diagnostic of the event
self.logs.append(f"post_execute: event {ev.get('type', 'unknown')}")
except Exception:
pass
if drained:
try:
with self.thread_lock:
self.logs.append(f"post_execute: flushed {drained} recv_events")
except Exception:
pass
except Exception as e:
try:
with self.thread_lock:
self.logs.append(f"post_execute handler error: {e}")
except Exception:
pass
[docs]
def register_post_execute(self):
"""Register the `_post_execute_handler` with IPython's post_execute event.
Returns True if registration succeeded.
"""
try:
ip = get_ipython()
if ip is None:
return False
try:
ip.events.register('post_execute', self._post_execute_handler)
try:
if getattr(self, 'debug', False):
with self.thread_lock:
self.logs.append('Registered post_execute handler for recv_events')
except Exception:
pass
return True
except Exception:
try:
with self.thread_lock:
self.logs.append('Failed to register post_execute handler')
except Exception:
pass
return False
except Exception:
return False
[docs]
def handle_recv(self, msg):
"""Handle a message received via IPython Comm (command response).
Event-type messages are routed via the out-of-band socket; this method
processes response messages delivered over IPython Comm.
"""
# Normalize incoming payload
try:
if isinstance(msg['content']['data'], str):
_data = json.loads(msg['content']['data'])
else:
_data = msg['content']['data']
except Exception:
try:
with self.thread_lock:
self.logs.append('Malformed comm message received')
except Exception:
pass
return
# If the message contains an 'id' field treat it as a response
_id = _data.get('id') if isinstance(_data, dict) else None
if _id:
with self.thread_lock:
fut = self.pending_futures.pop(_id, None)
if fut:
try:
import asyncio as _asyncio
try:
is_asyncio = isinstance(fut, _asyncio.Future)
except Exception:
is_asyncio = False
if is_asyncio:
loop = None
try:
get_loop = getattr(fut, 'get_loop', None)
if callable(get_loop):
loop = get_loop()
except Exception:
loop = getattr(fut, '_loop', None)
if loop is not None and getattr(loop, 'is_running', lambda: False)():
loop.call_soon_threadsafe(fut.set_result, _data.get('payload'))
else:
fut.set_result(_data.get('payload'))
else:
fut.set_result(_data.get('payload'))
except Exception:
try:
with self.thread_lock:
self.logs.append(f"Error setting result for id {_id}")
except Exception:
pass
else:
try:
with self.thread_lock:
self.logs.append(f"Unexpected response for id {_id}")
except Exception:
pass
return
# Otherwise it's an event message: enqueue for consumers
try:
self.recv_events.put(_data)
except Exception:
try:
with self.thread_lock:
self.logs.append('Failed to enqueue recv event')
except Exception:
pass
return
[docs]
def send(self, msg):
"""Send a message via the IPython Comm channel."""
with self.thread_lock:
tc = self.target_comm
if tc:
# Prefer scheduling the send on the kernel I/O loop if available
try:
kernel = get_ipython().kernel
io_loop = getattr(kernel, 'io_loop', None)
if io_loop is not None and hasattr(io_loop, 'add_callback'):
try:
io_loop.add_callback(lambda: tc.send(msg))
return
except Exception:
# fall through to direct send
pass
except Exception:
pass
return tc.send(msg)
# No widget-bridge fallback supported; require active IPython Comm
raise RuntimeError("No active Comm: GeoGebra().init() must be called in a notebook cell before sending commands.")
# Widget-bridge fallback removed: rely on IPython Comm target only.
[docs]
async def send_recv(self, msg):
"""Send a message via IPython Comm and wait for response via out-of-band socket.
This method:
1. Generates a unique message ID (UUID)
2. Sends the message via IPython Comm to the frontend
3. Waits for the response to arrive via the out-of-band socket
4. Raises GeoGebraAppletError if error events are received
5. Returns the response payload
The 3-second timeout is sufficient for interactive operations.
For long-running operations, decompose into smaller steps.
Args:
msg (dict or str): Message to send (will be JSON-serialized).
Returns:
dict: Response payload from GeoGebra.
Raises:
asyncio.TimeoutError: If no response arrives within 3 seconds.
GeoGebraAppletError: If the applet produces error events.
Example:
>>> response = await comm.send_recv({
... "type": "command",
... "payload": "A=(0,0)"
... })
"""
try:
if isinstance(msg, str):
_data = json.loads(msg)
else:
_data = msg
# Note: applet start handshake removed; rely on out-of-band responses.
_id = str(uuid.uuid4())
self.mid = _id
msg['id'] = _id
# Register a concurrent.futures.Future that client_handle will fulfill.
fut = concurrent.futures.Future()
with self.thread_lock:
self.pending_futures[_id] = fut
# If no OOB clients are connected, wait a short while for one to appear.
with self.thread_lock:
has_clients = bool(self.clients)
has_target = self.target_comm is not None
if not has_clients and not has_target:
try:
with self.thread_lock:
self.logs.append(f"No clients; waiting for client before sending {_id}")
except Exception:
pass
waited = 0.0
while waited < 2.0:
with self.thread_lock:
if self.clients or self.target_comm:
break
await asyncio.sleep(0.05)
waited += 0.05
# Send after registering the future to avoid races.
self.send(json.dumps(_data))
# Yield to the event loop to allow the OOB client handler to run
await asyncio.sleep(0)
# Schedule a watchdog to ensure the future doesn't hang indefinitely.
loop = asyncio.get_running_loop()
def _watchdog():
if not fut.done():
try:
fut.set_exception(asyncio.TimeoutError("oob future timed out"))
except Exception:
pass
handle = loop.call_later(3.0, _watchdog)
# Await the future (it will be set by client_handle or by watchdog)
try:
value = await asyncio.wrap_future(fut)
finally:
# cancel watchdog and remove mapping
handle.cancel()
with self.thread_lock:
self.pending_futures.pop(_id, None)
# If response value is empty, check for error events
if value is None:
# Wait a bit for error events to arrive
await asyncio.sleep(0.5)
# Check for error events in recv_events
error_messages = []
while True:
try:
event = self.recv_events.get_nowait()
if event.get('type') == 'Error':
error_messages.append(event.get('payload', 'Unknown error'))
except queue.Empty:
break
# If errors were collected, raise GeoGebraAppletError
if error_messages:
combined_message = '\n'.join(error_messages)
raise GeoGebraAppletError(
error_message=combined_message,
error_type='AppletError'
)
return value
except (asyncio.TimeoutError, TimeoutError):
# On timeout, raise the error
print(f"TimeoutError in send_recv {msg}")
raise
[docs]
@classmethod
def kernel_comm_summary(cls):
"""Return a summary of kernel Comm targets and open comms.
This helper inspects the running IPython kernel's CommManager and
returns a serializable dict with:
- targets: mapping of target_name -> callback name/type
- comms: mapping of comm_id -> basic info (target_name, metadata)
Useful for debugging from the kernel side to see which comm targets
are registered and which comms are currently open.
"""
ip = get_ipython()
kernel = getattr(ip, 'kernel', None)
cm = getattr(kernel, 'comm_manager', None)
result = {'targets': {}, 'comms': {}}
if cm is None:
return result
try:
targets = getattr(cm, 'targets', {}) or {}
for tname, cb in targets.items():
try:
result['targets'][tname] = getattr(cb, '__name__', type(cb).__name__)
except Exception:
result['targets'][tname] = str(cb)
except Exception:
pass
try:
comms = getattr(cm, 'comms', {}) or {}
for cid, comm in comms.items():
try:
result['comms'][cid] = {
'target_name': getattr(comm, 'target_name', None),
'target_module': getattr(comm, 'target_module', None),
'metadata': getattr(comm, 'metadata', None)
}
except Exception:
result['comms'][cid] = str(comm)
except Exception:
pass
return result
# Module-level singleton used by kernel extension loader and examples.
# Creating the instance is cheap; the out-of-band server only starts when
# `start()` is called by consumers.
try:
ggb_comm_instance
except NameError:
ggb_comm_instance = ggb_comm()
def kernel_comm_summary():
"""Convenience wrapper returning kernel comm summary.
Returns the same dict as `ggb_comm.kernel_comm_summary()`.
"""
try:
return ggb_comm.kernel_comm_summary()
except Exception:
return {'targets': {}, 'comms': {}}