Merge pull request #30 from meejah/25.bufferbloat

producer/consumer
master
meejah 2 years ago committed by GitHub
commit db48e91531
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@ -0,0 +1,208 @@
from io import (
StringIO,
)
import sys
import shutil
from twisted.trial import unittest
from twisted.internet.interfaces import (
IPullProducer,
)
from twisted.internet.protocol import (
ProcessProtocol,
)
from twisted.internet.defer import (
inlineCallbacks,
Deferred,
)
from autobahn.twisted.websocket import (
WebSocketClientProtocol,
create_client_agent,
)
from zope.interface import implementer
class _CollectOutputProtocol(ProcessProtocol):
"""
Internal helper. Collects all output (stdout + stderr) into
self.output, and callback's on done with all of it after the
process exits (for any reason).
"""
def __init__(self):
self.done = Deferred()
self.running = Deferred()
self.output = StringIO()
def processEnded(self, reason):
if not self.done.called:
self.done.callback(self.output.getvalue())
def outReceived(self, data):
print(data.decode(), end="", flush=True)
self.output.write(data.decode(sys.getfilesystemencoding()))
if not self.running.called:
if "on 8088" in self.output.getvalue():
self.running.callback(None)
def errReceived(self, data):
print("ERR: {}".format(data.decode(sys.getfilesystemencoding())))
self.output.write(data.decode(sys.getfilesystemencoding()))
def run_transit(reactor, proto, tcp_port=None, websocket_port=None):
exe = shutil.which("twistd")
args = [
exe, "-n", "transitrelay",
]
if tcp_port is not None:
args.append("--port")
args.append(tcp_port)
if websocket_port is not None:
args.append("--websocket")
args.append(websocket_port)
proc = reactor.spawnProcess(proto, exe, args)
return proc
class Sender(WebSocketClientProtocol):
"""
"""
def __init__(self, *args, **kw):
WebSocketClientProtocol.__init__(self, *args, **kw)
self.done = Deferred()
self.got_ok = Deferred()
def onMessage(self, payload, is_binary):
print("onMessage")
if not self.got_ok.called:
if payload == b"ok\n":
self.got_ok.callback(None)
print("send: {}".format(payload.decode("utf8")))
def onClose(self, clean, code, reason):
print(f"close: {clean} {code} {reason}")
self.done.callback(None)
class Receiver(WebSocketClientProtocol):
"""
"""
def __init__(self, *args, **kw):
WebSocketClientProtocol.__init__(self, *args, **kw)
self.done = Deferred()
self.first_message = Deferred()
self.received = 0
def onMessage(self, payload, is_binary):
print("recv: {}".format(len(payload)))
self.received += len(payload)
if not self.first_message.called:
self.first_message.callback(None)
def onClose(self, clean, code, reason):
print(f"close: {clean} {code} {reason}")
self.done.callback(None)
class TransitWebSockets(unittest.TestCase):
"""
Integration-style tests of the transit WebSocket relay, using the
real reactor (and running transit as a subprocess).
"""
@inlineCallbacks
def test_buffer_fills(self):
"""
A running transit relay stops accepting incoming data at a
reasonable amount if the peer isn't reading. This test defines
that as 'less than 100MiB' although in practice Twisted seems
to stop before 10MiB.
"""
from twisted.internet import reactor
transit_proto = _CollectOutputProtocol()
transit_proc = run_transit(reactor, transit_proto, websocket_port="tcp:8088")
def cleanup_process():
transit_proc.signalProcess("HUP")
return transit_proto.done
self.addCleanup(cleanup_process)
yield transit_proto.running
print("Transit running")
agent = create_client_agent(reactor)
side_a = yield agent.open("ws://localhost:8088", {}, lambda: Sender())
side_b = yield agent.open("ws://localhost:8088", {}, lambda: Receiver())
side_a.sendMessage(b"please relay aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa for side aaaaaaaaaaaaaaaa", True)
side_b.sendMessage(b"please relay aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa for side bbbbbbbbbbbbbbbb", True)
yield side_a.got_ok
yield side_b.first_message
# remove side_b's filedescriptor from the reactor .. this
# means it will not read any more data
reactor.removeReader(side_b.transport)
# attempt to send up to 100MiB through side_a .. we should get
# backpressure before that works which only manifests itself
# as this producer not being asked to produce more
max_data = 1024*1024*100 # 100MiB
@implementer(IPullProducer)
class ProduceMessages:
def __init__(self, ws, on_produce):
self._ws = ws
self._sent = 0
self._max = max_data
self._on_produce = on_produce
def resumeProducing(self):
self._on_produce()
if self._sent >= self._max:
self._ws.sendClose()
return
data = b"a" * 1024*1024
self._ws.sendMessage(data, True)
self._sent += len(data)
print("sent {}, total {}".format(len(data), self._sent))
# our only signal is, "did our producer get asked to produce
# more data" which it should do periodically. We want to stop
# if we haven't seen a new data request for a while -- defined
# as "more than 5 seconds".
done = Deferred()
last_produce = None
timeout = 2 # seconds
def asked_for_data():
nonlocal last_produce
last_produce = reactor.seconds()
data = ProduceMessages(side_a, asked_for_data)
side_a.transport.registerProducer(data, False)
data.resumeProducing()
def check_if_done():
if last_produce is not None:
if reactor.seconds() - last_produce > timeout:
done.callback(None)
return
# recursive call to ourselves to check again soon
reactor.callLater(.1, check_if_done)
check_if_done()
yield done
mib = 1024*1024.0
print("Sent {}MiB of {}MiB before backpressure".format(data._sent / mib, max_data / mib))
self.assertTrue(data._sent < max_data, "Too much data sent")
side_a.sendClose()
side_b.sendClose()
yield side_a.done
yield side_b.done

@ -47,6 +47,7 @@ class TransitConnection(LineReceiver):
ITransitClient API
"""
self._buddy = other
self._buddy._client.transport.registerProducer(self.transport, True)
def disconnect_partner(self):
"""
@ -198,6 +199,7 @@ class WebSocketTransitConnection(WebSocketServerProtocol):
ITransitClient API
"""
self._buddy = other
self._buddy._client.transport.registerProducer(self.transport, True)
def disconnect_partner(self):
"""

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