Broadcast server awareness to all clients (#73)

* Add methods to modify the awareness server side, server being a regular user

* Server can subscribe to awareness changes (only those from the frontend)

* mypy

* Add tests

* ruff and mypy

* Avoid depending on nest_asyncio

* Use the YRoom task group for asyncrhonous call

* Remove the Awareness object in favor of a futur one in pycrdt

* Apply suggestions from code review

Co-authored-by: David Brochart <[email protected]>

* Log an error if the task group is not initialized

* Update pycrdt_websocket/yroom.py

Co-authored-by: David Brochart <[email protected]>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Remove the logger in the Awareness args

* Docstring

* Update to pycrdt 0.10 and observe the awareness changes to broadcast local changes

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* mypy

* Apply suggestions

Co-authored-by: David Brochart <[email protected]>

* Broadcast the changes only if the state actually changes

* Apply suggestions from code review

Co-authored-by: David Brochart <[email protected]>

* Broadcast all updates

Co-authored-by: David Brochart <[email protected]>

* Update pyproject.toml

Co-authored-by: David Brochart <[email protected]>

---------

Co-authored-by: David Brochart <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: David Brochart <[email protected]>

pycrdt_websocket/yroom.py

@@ -4,7 +4,7 @@
 from functools import partial
 from inspect import isawaitable
 from logging import Logger, getLogger
-from typing import Awaitable, Callable
+from typing import Any, Awaitable, Callable
 
 from anyio import (
     TASK_STATUS_IGNORED,
@@ -16,16 +16,17 @@
 from anyio.abc import TaskGroup, TaskStatus
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
 from pycrdt import (
+    Awareness,
     Doc,
     Subscription,
     YMessageType,
     YSyncMessageType,
+    create_awareness_message,
     create_sync_message,
     create_update_message,
     handle_sync_message,
 )
 
-from .awareness import Awareness
 from .websocket import Websocket
 from .ystore import BaseYStore
 from .yutils import put_updates
@@ -77,11 +78,12 @@ def __init__(
             ydoc: An optional document for the room (a new one is created otherwise).
         """
         self.ydoc = Doc() if ydoc is None else ydoc
-        self.awareness = Awareness(self.ydoc)
         self.ready_event = Event()
         self.ready = ready
         self.ystore = ystore
         self.log = log or getLogger(__name__)
+        self.awareness = Awareness(self.ydoc)
+        self.awareness.observe(self.send_server_awareness)
         self.clients = set()
         self._on_message = None
         self.exception_handler = exception_handler
@@ -304,3 +306,34 @@ async def serve(self, websocket: Websocket):
                 self.clients.remove(websocket)
         except Exception as exception:
             self._handle_exception(exception)
+
+    def send_server_awareness(self, type: str, changes: tuple[dict[str, Any], Any]) -> None:
+        """
+        Callback to broadcast the server awareness to clients.
+
+        Arguments:
+            type: The change type.
+            changes: The awareness changes.
+        """
+        if type != "update" or changes[1] != "local":
+            return
+
+        if self._task_group is not None:
+            updated_clients = [v for value in changes[0].values() for v in value]
+            state = self.awareness.encode_awareness_update(updated_clients)
+            message = create_awareness_message(state)
+            self._task_group.start_soon(self._send_server_awareness, message)
+        else:
+            self.log.error("Cannot broadcast server awareness: YRoom not started")
+
+    async def _send_server_awareness(self, state: bytes) -> None:
+        try:
+            async with create_task_group() as tg:
+                for client in self.clients:
+                    self.log.debug(
+                        "Sending awareness from server to client with endpoint: %s",
+                        client.path,
+                    )
+                    tg.start_soon(client.send, state)
+        except Exception as e:
+            self.log.error("Error while broadcasting awareness changes: %s", e)

pyproject.toml

@@ -30,7 +30,7 @@ classifiers = [
 dependencies = [
     "anyio >=3.6.2,<5",
     "sqlite-anyio >=0.2.3,<0.3.0",
-    "pycrdt >=0.9.16,<0.10.0",
+    "pycrdt >=0.10.1,<0.11.0",
 ]
 
 [project.optional-dependencies]