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# Copyright 2022 The Matrix.org Foundation C.I.C.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
import time
from selectors import SelectSelector, _PollLikeSelector # type: ignore[attr-defined]
from typing import Any, Callable, Iterable
from prometheus_client import Histogram, Metric
from prometheus_client.core import REGISTRY, GaugeMetricFamily
from twisted.internet import reactor, selectreactor
from twisted.internet.asyncioreactor import AsyncioSelectorReactor
from synapse.metrics._types import Collector
try:
from selectors import KqueueSelector
except ImportError:
class KqueueSelector: # type: ignore[no-redef]
pass
try:
from twisted.internet.epollreactor import EPollReactor
except ImportError:
class EPollReactor: # type: ignore[no-redef]
pass
try:
from twisted.internet.pollreactor import PollReactor
except ImportError:
class PollReactor: # type: ignore[no-redef]
pass
logger = logging.getLogger(__name__)
#
# Twisted reactor metrics
#
tick_time = Histogram(
"python_twisted_reactor_tick_time",
"Tick time of the Twisted reactor (sec)",
buckets=[0.001, 0.002, 0.005, 0.01, 0.025, 0.05, 0.1, 0.2, 0.5, 1, 2, 5],
)
class CallWrapper:
"""A wrapper for a callable which records the time between calls"""
def __init__(self, wrapped: Callable[..., Any]):
self.last_polled = time.time()
self._wrapped = wrapped
def __call__(self, *args, **kwargs) -> Any: # type: ignore[no-untyped-def]
# record the time since this was last called. This gives a good proxy for
# how long it takes to run everything in the reactor - ie, how long anything
# waiting for the next tick will have to wait.
tick_time.observe(time.time() - self.last_polled)
ret = self._wrapped(*args, **kwargs)
self.last_polled = time.time()
return ret
class ObjWrapper:
"""A wrapper for an object which wraps a specified method in CallWrapper.
Other methods/attributes are passed to the original object.
This is necessary when the wrapped object does not allow the attribute to be
overwritten.
"""
def __init__(self, wrapped: Any, method_name: str):
self._wrapped = wrapped
self._method_name = method_name
self._wrapped_method = CallWrapper(getattr(wrapped, method_name))
def __getattr__(self, item: str) -> Any:
if item == self._method_name:
return self._wrapped_method
return getattr(self._wrapped, item)
class ReactorLastSeenMetric(Collector):
def __init__(self, call_wrapper: CallWrapper):
self._call_wrapper = call_wrapper
def collect(self) -> Iterable[Metric]:
cm = GaugeMetricFamily(
"python_twisted_reactor_last_seen",
"Seconds since the Twisted reactor was last seen",
)
cm.add_metric([], time.time() - self._call_wrapper.last_polled)
yield cm
# Twisted has already select a reasonable reactor for us, so assumptions can be
# made about the shape.
wrapper = None
try:
if isinstance(reactor, (PollReactor, EPollReactor)):
reactor._poller = ObjWrapper(reactor._poller, "poll") # type: ignore[attr-defined]
wrapper = reactor._poller._wrapped_method # type: ignore[attr-defined]
elif isinstance(reactor, selectreactor.SelectReactor):
# Twisted uses a module-level _select function.
wrapper = selectreactor._select = CallWrapper(selectreactor._select)
elif isinstance(reactor, AsyncioSelectorReactor):
# For asyncio look at the underlying asyncio event loop.
asyncio_loop = reactor._asyncioEventloop # A sub-class of BaseEventLoop,
# A sub-class of BaseSelector.
selector = asyncio_loop._selector # type: ignore[attr-defined]
if isinstance(selector, SelectSelector):
wrapper = selector._select = CallWrapper(selector._select) # type: ignore[attr-defined]
# poll, epoll, and /dev/poll.
elif isinstance(selector, _PollLikeSelector):
selector._selector = ObjWrapper(selector._selector, "poll") # type: ignore[attr-defined]
wrapper = selector._selector._wrapped_method # type: ignore[attr-defined]
elif isinstance(selector, KqueueSelector):
selector._selector = ObjWrapper(selector._selector, "control") # type: ignore[attr-defined]
wrapper = selector._selector._wrapped_method # type: ignore[attr-defined]
else:
# E.g. this does not support the (Windows-only) ProactorEventLoop.
logger.warning(
"Skipping configuring ReactorLastSeenMetric: unexpected asyncio loop selector: %r via %r",
selector,
asyncio_loop,
)
except Exception as e:
logger.warning("Configuring ReactorLastSeenMetric failed: %r", e)
if wrapper:
REGISTRY.register(ReactorLastSeenMetric(wrapper))
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