Skip to content

Room

Source code in pycrdt_websocket/yroom.py 
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
class YRoom:
    clients: list
    ydoc: Doc
    ystore: BaseYStore | None
    _on_message: Callable[[bytes], Awaitable[bool] | bool] | None
    _update_send_stream: MemoryObjectSendStream
    _update_receive_stream: MemoryObjectReceiveStream
    _ready: bool
    _task_group: TaskGroup | None
    _started: Event | None
    _starting: bool

    def __init__(
        self, ready: bool = True, ystore: BaseYStore | None = None, log: Logger | None = None
    ):
        """Initialize the object.

        The YRoom instance should preferably be used as an async context manager:
        ```py
        async with room:
            ...
        ```
        However, a lower-level API can also be used:
        ```py
        task = asyncio.create_task(room.start())
        await room.started.wait()
        ...
        room.stop()
        ```

        Arguments:
            ready: Whether the internal YDoc is ready to be synchronized right away.
            ystore: An optional store in which to persist document updates.
            log: An optional logger.
        """
        self.ydoc = Doc()
        self.awareness = Awareness(self.ydoc)
        self._update_send_stream, self._update_receive_stream = create_memory_object_stream(
            max_buffer_size=65536
        )
        self._ready = False
        self.ready = ready
        self.ystore = ystore
        self.log = log or getLogger(__name__)
        self.clients = []
        self._on_message = None
        self._started = None
        self._starting = False
        self._task_group = None

    @property
    def started(self):
        """An async event that is set when the YRoom provider has started."""
        if self._started is None:
            self._started = Event()
        return self._started

    @property
    def ready(self) -> bool:
        """
        Returns:
            True is the internal YDoc is ready to be synchronized.
        """
        return self._ready

    @ready.setter
    def ready(self, value: bool) -> None:
        """
        Arguments:
            value: True if the internal YDoc is ready to be synchronized, False otherwise."""
        self._ready = value
        if value:
            self.ydoc.observe(partial(put_updates, self._update_send_stream))

    @property
    def on_message(self) -> Callable[[bytes], Awaitable[bool] | bool] | None:
        """
        Returns:
            The optional callback to call when a message is received.
        """
        return self._on_message

    @on_message.setter
    def on_message(self, value: Callable[[bytes], Awaitable[bool] | bool] | None):
        """
        Arguments:
            value: An optional callback to call when a message is received.
            If the callback returns True, the message is skipped.
        """
        self._on_message = value

    async def _broadcast_updates(self):
        if self.ystore is not None and not self.ystore.started.is_set():
            self._task_group.start_soon(self.ystore.start)

        async with self._update_receive_stream:
            async for update in self._update_receive_stream:
                if self._task_group.cancel_scope.cancel_called:
                    return
                # broadcast internal ydoc's update to all clients, that includes changes from the
                # clients and changes from the backend (out-of-band changes)
                for client in self.clients:
                    self.log.debug("Sending Y update to client with endpoint: %s", client.path)
                    message = create_update_message(update)
                    self._task_group.start_soon(client.send, message)
                if self.ystore:
                    self.log.debug("Writing Y update to YStore")
                    self._task_group.start_soon(self.ystore.write, update)

    async def __aenter__(self) -> YRoom:
        if self._task_group is not None:
            raise RuntimeError("YRoom already running")

        async with AsyncExitStack() as exit_stack:
            tg = create_task_group()
            self._task_group = await exit_stack.enter_async_context(tg)
            self._exit_stack = exit_stack.pop_all()
            tg.start_soon(self._broadcast_updates)
            self.started.set()

        return self

    async def __aexit__(self, exc_type, exc_value, exc_tb):
        if self._task_group is None:
            raise RuntimeError("YRoom not running")

        self._task_group.cancel_scope.cancel()
        self._task_group = None
        return await self._exit_stack.__aexit__(exc_type, exc_value, exc_tb)

    async def start(self, *, task_status: TaskStatus[None] = TASK_STATUS_IGNORED):
        """Start the room.

        Arguments:
            task_status: The status to set when the task has started.
        """
        if self._starting:
            return
        else:
            self._starting = True

        if self._task_group is not None:
            raise RuntimeError("YRoom already running")

        async with create_task_group() as self._task_group:
            self._task_group.start_soon(self._broadcast_updates)
            self.started.set()
            self._starting = False
            task_status.started()

    def stop(self):
        """Stop the room."""
        if self._task_group is None:
            raise RuntimeError("YRoom not running")

        self._task_group.cancel_scope.cancel()
        self._task_group = None

    async def serve(self, websocket: Websocket):
        """Serve a client.

        Arguments:
            websocket: The WebSocket through which to serve the client.
        """
        async with create_task_group() as tg:
            self.clients.append(websocket)
            await sync(self.ydoc, websocket, self.log)
            try:
                async for message in websocket:
                    # filter messages (e.g. awareness)
                    skip = False
                    if self.on_message:
                        _skip = self.on_message(message)
                        skip = await _skip if isawaitable(_skip) else _skip
                    if skip:
                        continue
                    message_type = message[0]
                    if message_type == YMessageType.SYNC:
                        # update our internal state in the background
                        # changes to the internal state are then forwarded to all clients
                        # and stored in the YStore (if any)
                        tg.start_soon(
                            process_sync_message, message[1:], self.ydoc, websocket, self.log
                        )
                    elif message_type == YMessageType.AWARENESS:
                        # forward awareness messages from this client to all clients,
                        # including itself, because it's used to keep the connection alive
                        self.log.debug(
                            "Received %s message from endpoint: %s",
                            YMessageType.AWARENESS.name,
                            websocket.path,
                        )
                        for client in self.clients:
                            self.log.debug(
                                "Sending Y awareness from client with endpoint "
                                "%s to client with endpoint: %s",
                                websocket.path,
                                client.path,
                            )
                            tg.start_soon(client.send, message)
            except Exception as e:
                self.log.debug("Error serving endpoint: %s", websocket.path, exc_info=e)

            # remove this client
            self.clients = [c for c in self.clients if c != websocket]

on_message: Callable[[bytes], Awaitable[bool] | bool] | None property writable

Returns:

Type Description
Callable[[bytes], Awaitable[bool] | bool] | None

The optional callback to call when a message is received.

ready: bool property writable

Returns:

Type Description
bool

True is the internal YDoc is ready to be synchronized.

started property

An async event that is set when the YRoom provider has started.

__init__(ready=True, ystore=None, log=None)

Initialize the object.

The YRoom instance should preferably be used as an async context manager: 

async with room:
    ...
However, a lower-level API can also be used: 
task = asyncio.create_task(room.start())
await room.started.wait()
...
room.stop()

Parameters:

Name Type Description Default
ready bool

Whether the internal YDoc is ready to be synchronized right away.

 True
ystore BaseYStore | None

An optional store in which to persist document updates.

 None
log Logger | None

An optional logger.

 None
Source code in pycrdt_websocket/yroom.py 
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
def __init__(
    self, ready: bool = True, ystore: BaseYStore | None = None, log: Logger | None = None
):
    """Initialize the object.

    The YRoom instance should preferably be used as an async context manager:
    ```py
    async with room:
        ...
    ```
    However, a lower-level API can also be used:
    ```py
    task = asyncio.create_task(room.start())
    await room.started.wait()
    ...
    room.stop()
    ```

    Arguments:
        ready: Whether the internal YDoc is ready to be synchronized right away.
        ystore: An optional store in which to persist document updates.
        log: An optional logger.
    """
    self.ydoc = Doc()
    self.awareness = Awareness(self.ydoc)
    self._update_send_stream, self._update_receive_stream = create_memory_object_stream(
        max_buffer_size=65536
    )
    self._ready = False
    self.ready = ready
    self.ystore = ystore
    self.log = log or getLogger(__name__)
    self.clients = []
    self._on_message = None
    self._started = None
    self._starting = False
    self._task_group = None

serve(websocket) async

Serve a client.

Parameters:

Name Type Description Default
websocket Websocket

The WebSocket through which to serve the client.

 required
Source code in pycrdt_websocket/yroom.py 
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
async def serve(self, websocket: Websocket):
    """Serve a client.

    Arguments:
        websocket: The WebSocket through which to serve the client.
    """
    async with create_task_group() as tg:
        self.clients.append(websocket)
        await sync(self.ydoc, websocket, self.log)
        try:
            async for message in websocket:
                # filter messages (e.g. awareness)
                skip = False
                if self.on_message:
                    _skip = self.on_message(message)
                    skip = await _skip if isawaitable(_skip) else _skip
                if skip:
                    continue
                message_type = message[0]
                if message_type == YMessageType.SYNC:
                    # update our internal state in the background
                    # changes to the internal state are then forwarded to all clients
                    # and stored in the YStore (if any)
                    tg.start_soon(
                        process_sync_message, message[1:], self.ydoc, websocket, self.log
                    )
                elif message_type == YMessageType.AWARENESS:
                    # forward awareness messages from this client to all clients,
                    # including itself, because it's used to keep the connection alive
                    self.log.debug(
                        "Received %s message from endpoint: %s",
                        YMessageType.AWARENESS.name,
                        websocket.path,
                    )
                    for client in self.clients:
                        self.log.debug(
                            "Sending Y awareness from client with endpoint "
                            "%s to client with endpoint: %s",
                            websocket.path,
                            client.path,
                        )
                        tg.start_soon(client.send, message)
        except Exception as e:
            self.log.debug("Error serving endpoint: %s", websocket.path, exc_info=e)

        # remove this client
        self.clients = [c for c in self.clients if c != websocket]

start(*, task_status=TASK_STATUS_IGNORED) async

Start the room.

Parameters:

Name Type Description Default
task_status TaskStatus[None]

The status to set when the task has started.

 TASK_STATUS_IGNORED
Source code in pycrdt_websocket/yroom.py 
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
async def start(self, *, task_status: TaskStatus[None] = TASK_STATUS_IGNORED):
    """Start the room.

    Arguments:
        task_status: The status to set when the task has started.
    """
    if self._starting:
        return
    else:
        self._starting = True

    if self._task_group is not None:
        raise RuntimeError("YRoom already running")

    async with create_task_group() as self._task_group:
        self._task_group.start_soon(self._broadcast_updates)
        self.started.set()
        self._starting = False
        task_status.started()

stop()

Stop the room.

Source code in pycrdt_websocket/yroom.py 
181
182
183
184
185
186
187
def stop(self):
    """Stop the room."""
    if self._task_group is None:
        raise RuntimeError("YRoom not running")

    self._task_group.cancel_scope.cancel()
    self._task_group = None