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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 select
import time
from typing import Any, Iterable, List, Tuple
from prometheus_client import Histogram, Metric
from prometheus_client.core import REGISTRY, GaugeMetricFamily
from twisted.internet import reactor
from synapse.metrics._types import Collector
#
# 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 EpollWrapper:
"""a wrapper for an epoll object which records the time between polls"""
def __init__(self, poller: "select.epoll"): # type: ignore[name-defined]
self.last_polled = time.time()
self._poller = poller
def poll(self, *args, **kwargs) -> List[Tuple[int, int]]: # type: ignore[no-untyped-def]
# record the time since poll() 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._poller.poll(*args, **kwargs)
self.last_polled = time.time()
return ret
def __getattr__(self, item: str) -> Any:
return getattr(self._poller, item)
class ReactorLastSeenMetric(Collector):
def __init__(self, epoll_wrapper: EpollWrapper):
self._epoll_wrapper = epoll_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._epoll_wrapper.last_polled)
yield cm
try:
# if the reactor has a `_poller` attribute, which is an `epoll` object
# (ie, it's an EPollReactor), we wrap the `epoll` with a thing that will
# measure the time between ticks
from select import epoll # type: ignore[attr-defined]
poller = reactor._poller # type: ignore[attr-defined]
except (AttributeError, ImportError):
pass
else:
if isinstance(poller, epoll):
poller = EpollWrapper(poller)
reactor._poller = poller # type: ignore[attr-defined]
REGISTRY.register(ReactorLastSeenMetric(poller))
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