226 lines
6.2 KiB
Python
226 lines
6.2 KiB
Python
import asyncio
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import secrets
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import logging
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import websockets
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log = logging.getLogger(__name__)
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import syndicate.mini.protocol as protocol
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from syndicate.mini.protocol import Capture, Discard, Observe
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CAPTURE = Capture(Discard())
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from preserves import *
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_instance_id = secrets.token_urlsafe(8)
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_uuid_counter = 0
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def uuid(prefix='__@syndicate'):
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global _uuid_counter
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c = _uuid_counter
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_uuid_counter = c + 1
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return prefix + '_' + _instance_id + '_' + str(c)
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def _ignore(*args, **kwargs):
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pass
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class Endpoint(object):
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def __init__(self, conn, assertion, id=None, on_add=None, on_del=None, on_msg=None):
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self.conn = conn
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self.assertion = assertion
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self.id = id or uuid('sub' if Observe.isClassOf(assertion) else 'pub')
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self.on_add = on_add or _ignore
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self.on_del = on_del or _ignore
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self.on_msg = on_msg or _ignore
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self.cache = set()
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self.conn._update_endpoint(self)
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def set(self, new_assertion):
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self.assertion = new_assertion
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if self.conn:
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self.conn._update_endpoint(self)
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def send(self, message):
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'''Shortcut to Connection.send.'''
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if self.conn:
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self.conn.send(message)
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def destroy(self):
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if self.conn:
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self.conn._clear_endpoint(self)
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self.conn = None
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def _reset(self):
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for captures in set(self.cache):
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self._del(captures)
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def _add(self, captures):
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if captures not in self.cache:
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self.cache.add(captures)
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self.on_add(*captures)
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def _del(self, captures):
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if captures in self.cache:
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self.cache.discard(captures)
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self.on_del(*captures)
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def _msg(self, captures):
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self.on_msg(*captures)
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class DummyEndpoint(object):
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def _add(self, captures): pass
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def _del(self, captures): pass
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def _msg(self, captures): pass
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_dummy_endpoint = DummyEndpoint()
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class Connection(object):
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def __init__(self):
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self.endpoints = {}
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def _each_endpoint(self):
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return list(self.endpoints.values())
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def destroy(self):
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for ep in self._each_endpoint():
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ep.destroy()
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self._disconnect()
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def _encode(self, event):
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e = protocol.Encoder()
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e.append(event)
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return e.contents()
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def _update_endpoint(self, ep):
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self.endpoints[ep.id] = ep
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self._send(self._encode(protocol.Assert(ep.id, ep.assertion)))
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def _clear_endpoint(self, ep):
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if ep.id in self.endpoints:
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del self.endpoints[ep.id]
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self._send(self._encode(protocol.Clear(ep.id)))
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def send(self, message):
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self._send(self._encode(protocol.Message(message)))
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def _on_disconnected(self):
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for ep in self._each_endpoint():
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ep._reset()
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self._disconnect()
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def _on_connected(self):
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for ep in self._each_endpoint():
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self._update_endpoint(ep)
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def _lookup(self, endpointId):
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return self.endpoints.get(endpointId, _dummy_endpoint)
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def _on_event(self, v):
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if protocol.Add.isClassOf(v): return self._lookup(v[0])._add(v[1])
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if protocol.Del.isClassOf(v): return self._lookup(v[0])._del(v[1])
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if protocol.Msg.isClassOf(v): return self._lookup(v[0])._msg(v[1])
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def _send(self, bs):
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raise Exception('subclassresponsibility')
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def _disconnect(self):
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raise Exception('subclassresponsibility')
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class TcpConnection(Connection, asyncio.Protocol):
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def __init__(self, host, port):
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super().__init__()
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self.host = host
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self.port = port
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self.decoder = None
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self.stop_signal = None
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self.transport = None
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def connection_lost(self, exc):
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self._on_disconnected()
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def connection_made(self, transport):
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self.transport = transport
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self._on_connected()
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def data_received(self, chunk):
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self.decoder.extend(chunk)
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while True:
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v = self.decoder.try_next()
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if v is None: break
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self._on_event(v)
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def _send(self, bs):
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if self.transport:
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self.transport.write(bs)
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def _disconnect(self):
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if self.stop_signal:
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self.stop_signal.set_result(True)
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async def main(self, loop):
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if self.transport is not None:
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raise Exception('Cannot run connection twice!')
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self.decoder = protocol.Decoder()
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self.stop_signal = loop.create_future()
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try:
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_transport, _protocol = await loop.create_connection(
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lambda: self,
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self.host,
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self.port)
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except OSError:
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log.error('Could not connect to broker', exc_info=True)
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return False
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try:
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await self.stop_signal
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return True
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finally:
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self.transport.close()
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self.transport = None
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self.stop_signal = None
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self.decoder = None
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class WebsocketConnection(Connection):
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def __init__(self, url):
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super().__init__()
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self.url = url
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self.loop = None
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self.ws = None
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def _send(self, bs):
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if self.ws:
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self.loop.call_soon_threadsafe(lambda: self.loop.create_task(self.ws.send(bs)))
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def _disconnect(self):
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if self.ws:
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self.loop.call_soon_threadsafe(lambda: self.loop.create_task(self.ws.close()))
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async def main(self, loop):
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if self.ws is not None:
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raise Exception('Cannot run connection twice!')
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self.loop = loop
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try:
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async with websockets.connect(self.url) as ws:
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self.ws = ws
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self._on_connected()
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try:
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while True:
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chunk = await loop.create_task(ws.recv())
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self._on_event(protocol.Decoder(chunk).next())
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except websockets.exceptions.ConnectionClosed:
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pass
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except OSError:
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log.error('Could not connect to broker', exc_info=True)
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return False
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finally:
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self._on_disconnected()
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if self.ws:
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await self.ws.close()
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self.loop = None
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self.ws = None
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return True
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