import asyncio
import logging
import random
import engineio
from . import client
from . import exceptions
from . import packet
default_logger = logging.getLogger('socketio.client')
class AsyncClient(client.Client):
"""A Socket.IO client for asyncio.
This class implements a fully compliant Socket.IO web client with support
for websocket and long-polling transports.
:param reconnection: ``True`` if the client should automatically attempt to
reconnect to the server after an interruption, or
``False`` to not reconnect. The default is ``True``.
:param reconnection_attempts: How many reconnection attempts to issue
before giving up, or 0 for infinity attempts.
The default is 0.
:param reconnection_delay: How long to wait in seconds before the first
reconnection attempt. Each successive attempt
doubles this delay.
:param reconnection_delay_max: The maximum delay between reconnection
attempts.
:param randomization_factor: Randomization amount for each delay between
reconnection attempts. The default is 0.5,
which means that each delay is randomly
adjusted by +/- 50%.
:param logger: To enable logging set to ``True`` or pass a logger object to
use. To disable logging set to ``False``. The default is
``False``. Note that fatal errors are logged even when
``logger`` is ``False``.
:param json: An alternative json module to use for encoding and decoding
packets. Custom json modules must have ``dumps`` and ``loads``
functions that are compatible with the standard library
versions.
The Engine.IO configuration supports the following settings:
:param request_timeout: A timeout in seconds for requests. The default is
5 seconds.
:param http_session: an initialized ``requests.Session`` object to be used
when sending requests to the server. Use it if you
need to add special client options such as proxy
servers, SSL certificates, etc.
:param ssl_verify: ``True`` to verify SSL certificates, or ``False`` to
skip SSL certificate verification, allowing
connections to servers with self signed certificates.
The default is ``True``.
:param engineio_logger: To enable Engine.IO logging set to ``True`` or pass
a logger object to use. To disable logging set to
``False``. The default is ``False``. Note that
fatal errors are logged even when
``engineio_logger`` is ``False``.
"""
def is_asyncio_based(self):
return True
async def connect(self, url, headers={}, transports=None,
namespaces=None, socketio_path='socket.io'):
"""Connect to a Socket.IO server.
:param url: The URL of the Socket.IO server. It can include custom
query string parameters if required by the server.
:param headers: A dictionary with custom headers to send with the
connection request.
:param transports: The list of allowed transports. Valid transports
are ``'polling'`` and ``'websocket'``. If not
given, the polling transport is connected first,
then an upgrade to websocket is attempted.
:param namespaces: The namespaces to connect as a string or list of
strings. If not given, the namespaces that have
registered event handlers are connected.
:param socketio_path: The endpoint where the Socket.IO server is
installed. The default value is appropriate for
most cases.
Note: this method is a coroutine.
Note: The connection mechannism occurs in the background and will
complete at some point after this function returns. The connection
will be established when the ``connect`` event is invoked.
Example usage::
sio = socketio.AsyncClient()
sio.connect('http://localhost:5000')
"""
self.connection_url = url
self.connection_headers = headers
self.connection_transports = transports
self.connection_namespaces = namespaces
self.socketio_path = socketio_path
if namespaces is None:
namespaces = list(set(self.handlers.keys()).union(
set(self.namespace_handlers.keys())))
if len(namespaces) == 0:
namespaces = ['/']
elif isinstance(namespaces, str):
namespaces = [namespaces]
self.connection_namespaces = namespaces
try:
await self.eio.connect(url, headers=headers,
transports=transports,
engineio_path=socketio_path)
except engineio.exceptions.ConnectionError as exc:
await self._trigger_event(
'connect_error', '/',
exc.args[1] if len(exc.args) > 1 else exc.args[0])
raise exceptions.ConnectionError(exc.args[0]) from None
self.connected = True
async def wait(self):
"""Wait until the connection with the server ends.
Client applications can use this function to block the main thread
during the life of the connection.
Note: this method is a coroutine.
"""
while True:
await self.eio.wait()
await self.sleep(1) # give the reconnect task time to start up
if not self._reconnect_task:
break
await self._reconnect_task
if self.eio.state != 'connected':
break
async def emit(self, event, data=None, namespace=None, callback=None):
"""Emit a custom event to one or more connected clients.
:param event: The event name. It can be any string. The event names
``'connect'``, ``'message'`` and ``'disconnect'`` are
reserved and should not be used.
:param data: The data to send to the server. Data can be of
type ``str``, ``bytes``, ``list`` or ``dict``. To send
multiple arguments, use a tuple where each element is of
one of the types indicated above.
:param namespace: The Socket.IO namespace for the event. If this
argument is omitted the event is emitted to the
default namespace.
:param callback: If given, this function will be called to acknowledge
the the server has received the message. The arguments
that will be passed to the function are those provided
by the server.
Note: this method is not designed to be used concurrently. If multiple
tasks are emitting at the same time on the same client connection, then
messages composed of multiple packets may end up being sent in an
incorrect sequence. Use standard concurrency solutions (such as a Lock
object) to prevent this situation.
Note 2: this method is a coroutine.
"""
namespace = namespace or '/'
if namespace not in self.namespaces:
raise exceptions.BadNamespaceError(
namespace + ' is not a connected namespace.')
self.logger.info('Emitting event "%s" [%s]', event, namespace)
if callback is not None:
id = self._generate_ack_id(namespace, callback)
else:
id = None
# tuples are expanded to multiple arguments, everything else is sent
# as a single argument
if isinstance(data, tuple):
data = list(data)
elif data is not None:
data = [data]
else:
data = []
await self._send_packet(packet.Packet(
packet.EVENT, namespace=namespace, data=[event] + data, id=id))
async def send(self, data, namespace=None, callback=None):
"""Send a message to one or more connected clients.
This function emits an event with the name ``'message'``. Use
:func:`emit` to issue custom event names.
:param data: The data to send to the server. Data can be of
type ``str``, ``bytes``, ``list`` or ``dict``. To send
multiple arguments, use a tuple where each element is of
one of the types indicated above.
:param namespace: The Socket.IO namespace for the event. If this
argument is omitted the event is emitted to the
default namespace.
:param callback: If given, this function will be called to acknowledge
the the server has received the message. The arguments
that will be passed to the function are those provided
by the server.
Note: this method is a coroutine.
"""
await self.emit('message', data=data, namespace=namespace,
callback=callback)
async def call(self, event, data=None, namespace=None, timeout=60):
"""Emit a custom event to a client and wait for the response.
:param event: The event name. It can be any string. The event names
``'connect'``, ``'message'`` and ``'disconnect'`` are
reserved and should not be used.
:param data: The data to send to the server. Data can be of
type ``str``, ``bytes``, ``list`` or ``dict``. To send
multiple arguments, use a tuple where each element is of
one of the types indicated above.
:param namespace: The Socket.IO namespace for the event. If this
argument is omitted the event is emitted to the
default namespace.
:param timeout: The waiting timeout. If the timeout is reached before
the client acknowledges the event, then a
``TimeoutError`` exception is raised.
Note: this method is not designed to be used concurrently. If multiple
tasks are emitting at the same time on the same client connection, then
messages composed of multiple packets may end up being sent in an
incorrect sequence. Use standard concurrency solutions (such as a Lock
object) to prevent this situation.
Note 2: this method is a coroutine.
"""
callback_event = self.eio.create_event()
callback_args = []
def event_callback(*args):
callback_args.append(args)
callback_event.set()
await self.emit(event, data=data, namespace=namespace,
callback=event_callback)
try:
await asyncio.wait_for(callback_event.wait(), timeout)
except asyncio.TimeoutError:
raise exceptions.TimeoutError() from None
return callback_args[0] if len(callback_args[0]) > 1 \
else callback_args[0][0] if len(callback_args[0]) == 1 \
else None
async def disconnect(self):
"""Disconnect from the server.
Note: this method is a coroutine.
"""
# here we just request the disconnection
# later in _handle_eio_disconnect we invoke the disconnect handler
for n in self.namespaces:
await self._send_packet(packet.Packet(packet.DISCONNECT,
namespace=n))
await self.eio.disconnect(abort=True)
def start_background_task(self, target, *args, **kwargs):
"""Start a background task using the appropriate async model.
This is a utility function that applications can use to start a
background task using the method that is compatible with the
selected async mode.
:param target: the target function to execute.
:param args: arguments to pass to the function.
:param kwargs: keyword arguments to pass to the function.
This function returns an object compatible with the `Thread` class in
the Python standard library. The `start()` method on this object is
already called by this function.
"""
return self.eio.start_background_task(target, *args, **kwargs)
async def sleep(self, seconds=0):
"""Sleep for the requested amount of time using the appropriate async
model.
This is a utility function that applications can use to put a task to
sleep without having to worry about using the correct call for the
selected async mode.
Note: this method is a coroutine.
"""
return await self.eio.sleep(seconds)
async def _send_packet(self, pkt):
"""Send a Socket.IO packet to the server."""
encoded_packet = pkt.encode()
if isinstance(encoded_packet, list):
for ep in encoded_packet:
await self.eio.send(ep)
else:
await self.eio.send(encoded_packet)
async def _handle_connect(self, namespace, data):
namespace = namespace or '/'
if namespace not in self.namespaces:
self.logger.info('Namespace {} is connected'.format(namespace))
self.namespaces[namespace] = (data or {}).get('sid', self.sid)
await self._trigger_event('connect', namespace=namespace)
async def _handle_disconnect(self, namespace):
if not self.connected:
return
namespace = namespace or '/'
await self._trigger_event('disconnect', namespace=namespace)
if namespace in self.namespaces:
del self.namespaces[namespace]
if not self.namespaces:
self.connected = False
await self.eio.disconnect(abort=True)
async def _handle_event(self, namespace, id, data):
namespace = namespace or '/'
self.logger.info('Received event "%s" [%s]', data[0], namespace)
r = await self._trigger_event(data[0], namespace, *data[1:])
if id is not None:
# send ACK packet with the response returned by the handler
# tuples are expanded as multiple arguments
if r is None:
data = []
elif isinstance(r, tuple):
data = list(r)
else:
data = [r]
await self._send_packet(packet.Packet(
packet.ACK, namespace=namespace, id=id, data=data))
async def _handle_ack(self, namespace, id, data):
namespace = namespace or '/'
self.logger.info('Received ack [%s]', namespace)
callback = None
try:
callback = self.callbacks[namespace][id]
except KeyError:
# if we get an unknown callback we just ignore it
self.logger.warning('Unknown callback received, ignoring.')
else:
del self.callbacks[namespace][id]
if callback is not None:
if asyncio.iscoroutinefunction(callback):
await callback(*data)
else:
callback(*data)
async def _handle_error(self, namespace, data):
namespace = namespace or '/'
self.logger.info('Connection to namespace {} was rejected'.format(
namespace))
if data is None:
data = tuple()
elif not isinstance(data, (tuple, list)):
data = (data,)
await self._trigger_event('connect_error', namespace, *data)
if namespace in self.namespaces:
del self.namespaces[namespace]
if namespace == '/':
self.namespaces = {}
self.connected = False
async def _trigger_event(self, event, namespace, *args):
"""Invoke an application event handler."""
# first see if we have an explicit handler for the event
if namespace in self.handlers and event in self.handlers[namespace]:
if asyncio.iscoroutinefunction(self.handlers[namespace][event]):
try:
ret = await self.handlers[namespace][event](*args)
except asyncio.CancelledError: # pragma: no cover
ret = None
else:
ret = self.handlers[namespace][event](*args)
return ret
# or else, forward the event to a namepsace handler if one exists
elif namespace in self.namespace_handlers:
return await self.namespace_handlers[namespace].trigger_event(
event, *args)
async def _handle_reconnect(self):
self._reconnect_abort.clear()
client.reconnecting_clients.append(self)
attempt_count = 0
current_delay = self.reconnection_delay
while True:
delay = current_delay
current_delay *= 2
if delay > self.reconnection_delay_max:
delay = self.reconnection_delay_max
delay += self.randomization_factor * (2 * random.random() - 1)
self.logger.info(
'Connection failed, new attempt in {:.02f} seconds'.format(
delay))
try:
await asyncio.wait_for(self._reconnect_abort.wait(), delay)
self.logger.info('Reconnect task aborted')
break
except (asyncio.TimeoutError, asyncio.CancelledError):
pass
attempt_count += 1
try:
await self.connect(self.connection_url,
headers=self.connection_headers,
transports=self.connection_transports,
namespaces=self.connection_namespaces,
socketio_path=self.socketio_path)
except (exceptions.ConnectionError, ValueError):
pass
else:
self.logger.info('Reconnection successful')
self._reconnect_task = None
break
if self.reconnection_attempts and \
attempt_count >= self.reconnection_attempts:
self.logger.info(
'Maximum reconnection attempts reached, giving up')
break
client.reconnecting_clients.remove(self)
async def _handle_eio_connect(self):
"""Handle the Engine.IO connection event."""
self.logger.info('Engine.IO connection established')
self.sid = self.eio.sid
for n in self.connection_namespaces:
await self._send_packet(packet.Packet(packet.CONNECT, namespace=n))
async def _handle_eio_message(self, data):
"""Dispatch Engine.IO messages."""
if self._binary_packet:
pkt = self._binary_packet
if pkt.add_attachment(data):
self._binary_packet = None
if pkt.packet_type == packet.BINARY_EVENT:
await self._handle_event(pkt.namespace, pkt.id, pkt.data)
else:
await self._handle_ack(pkt.namespace, pkt.id, pkt.data)
else:
pkt = packet.Packet(encoded_packet=data)
if pkt.packet_type == packet.CONNECT:
await self._handle_connect(pkt.namespace, pkt.data)
elif pkt.packet_type == packet.DISCONNECT:
await self._handle_disconnect(pkt.namespace)
elif pkt.packet_type == packet.EVENT:
await self._handle_event(pkt.namespace, pkt.id, pkt.data)
elif pkt.packet_type == packet.ACK:
await self._handle_ack(pkt.namespace, pkt.id, pkt.data)
elif pkt.packet_type == packet.BINARY_EVENT or \
pkt.packet_type == packet.BINARY_ACK:
self._binary_packet = pkt
elif pkt.packet_type == packet.CONNECT_ERROR:
await self._handle_error(pkt.namespace, pkt.data)
else:
raise ValueError('Unknown packet type.')
async def _handle_eio_disconnect(self):
"""Handle the Engine.IO disconnection event."""
self.logger.info('Engine.IO connection dropped')
self._reconnect_abort.set()
if self.connected:
for n in self.namespaces:
await self._trigger_event('disconnect', namespace=n)
self.namespaces = {}
self.connected = False
self.callbacks = {}
self._binary_packet = None
self.sid = None
if self.eio.state == 'connected' and self.reconnection:
self._reconnect_task = self.start_background_task(
self._handle_reconnect)
def _engineio_client_class(self):
return engineio.AsyncClient