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- # Copyright 2016 OpenMarket Ltd
- #
- # 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
- from functools import wraps
- from types import TracebackType
- from typing import Awaitable, Callable, Dict, Generator, Optional, Type, TypeVar
- from prometheus_client import CollectorRegistry, Counter, Metric
- from typing_extensions import Concatenate, ParamSpec, Protocol
- from synapse.logging.context import (
- ContextResourceUsage,
- LoggingContext,
- current_context,
- )
- from synapse.metrics import InFlightGauge
- from synapse.util import Clock
- logger = logging.getLogger(__name__)
- block_counter = Counter("synapse_util_metrics_block_count", "", ["block_name"])
- block_timer = Counter("synapse_util_metrics_block_time_seconds", "", ["block_name"])
- block_ru_utime = Counter(
- "synapse_util_metrics_block_ru_utime_seconds", "", ["block_name"]
- )
- block_ru_stime = Counter(
- "synapse_util_metrics_block_ru_stime_seconds", "", ["block_name"]
- )
- block_db_txn_count = Counter(
- "synapse_util_metrics_block_db_txn_count", "", ["block_name"]
- )
- # seconds spent waiting for db txns, excluding scheduling time, in this block
- block_db_txn_duration = Counter(
- "synapse_util_metrics_block_db_txn_duration_seconds", "", ["block_name"]
- )
- # seconds spent waiting for a db connection, in this block
- block_db_sched_duration = Counter(
- "synapse_util_metrics_block_db_sched_duration_seconds", "", ["block_name"]
- )
- # This is dynamically created in InFlightGauge.__init__.
- class _InFlightMetric(Protocol):
- real_time_max: float
- real_time_sum: float
- # Tracks the number of blocks currently active
- in_flight: InFlightGauge[_InFlightMetric] = InFlightGauge(
- "synapse_util_metrics_block_in_flight",
- "",
- labels=["block_name"],
- sub_metrics=["real_time_max", "real_time_sum"],
- )
- P = ParamSpec("P")
- R = TypeVar("R")
- class HasClock(Protocol):
- clock: Clock
- def measure_func(
- name: Optional[str] = None,
- ) -> Callable[[Callable[P, Awaitable[R]]], Callable[P, Awaitable[R]]]:
- """Decorate an async method with a `Measure` context manager.
- The Measure is created using `self.clock`; it should only be used to decorate
- methods in classes defining an instance-level `clock` attribute.
- Usage:
- @measure_func()
- async def foo(...):
- ...
- Which is analogous to:
- async def foo(...):
- with Measure(...):
- ...
- """
- def wrapper(
- func: Callable[Concatenate[HasClock, P], Awaitable[R]]
- ) -> Callable[P, Awaitable[R]]:
- block_name = func.__name__ if name is None else name
- @wraps(func)
- async def measured_func(self: HasClock, *args: P.args, **kwargs: P.kwargs) -> R:
- with Measure(self.clock, block_name):
- r = await func(self, *args, **kwargs)
- return r
- # There are some shenanigans here, because we're decorating a method but
- # explicitly making use of the `self` parameter. The key thing here is that the
- # return type within the return type for `measure_func` itself describes how the
- # decorated function will be called.
- return measured_func # type: ignore[return-value]
- return wrapper # type: ignore[return-value]
- class Measure:
- __slots__ = [
- "clock",
- "name",
- "_logging_context",
- "start",
- ]
- def __init__(self, clock: Clock, name: str) -> None:
- """
- Args:
- clock: An object with a "time()" method, which returns the current
- time in seconds.
- name: The name of the metric to report.
- """
- self.clock = clock
- self.name = name
- curr_context = current_context()
- if not curr_context:
- logger.warning(
- "Starting metrics collection %r from sentinel context: metrics will be lost",
- name,
- )
- parent_context = None
- else:
- assert isinstance(curr_context, LoggingContext)
- parent_context = curr_context
- self._logging_context = LoggingContext(str(curr_context), parent_context)
- self.start: Optional[float] = None
- def __enter__(self) -> "Measure":
- if self.start is not None:
- raise RuntimeError("Measure() objects cannot be re-used")
- self.start = self.clock.time()
- self._logging_context.__enter__()
- in_flight.register((self.name,), self._update_in_flight)
- logger.debug("Entering block %s", self.name)
- return self
- def __exit__(
- self,
- exc_type: Optional[Type[BaseException]],
- exc_val: Optional[BaseException],
- exc_tb: Optional[TracebackType],
- ) -> None:
- if self.start is None:
- raise RuntimeError("Measure() block exited without being entered")
- logger.debug("Exiting block %s", self.name)
- duration = self.clock.time() - self.start
- usage = self.get_resource_usage()
- in_flight.unregister((self.name,), self._update_in_flight)
- self._logging_context.__exit__(exc_type, exc_val, exc_tb)
- try:
- block_counter.labels(self.name).inc()
- block_timer.labels(self.name).inc(duration)
- block_ru_utime.labels(self.name).inc(usage.ru_utime)
- block_ru_stime.labels(self.name).inc(usage.ru_stime)
- block_db_txn_count.labels(self.name).inc(usage.db_txn_count)
- block_db_txn_duration.labels(self.name).inc(usage.db_txn_duration_sec)
- block_db_sched_duration.labels(self.name).inc(usage.db_sched_duration_sec)
- except ValueError:
- logger.warning("Failed to save metrics! Usage: %s", usage)
- def get_resource_usage(self) -> ContextResourceUsage:
- """Get the resources used within this Measure block
- If the Measure block is still active, returns the resource usage so far.
- """
- return self._logging_context.get_resource_usage()
- def _update_in_flight(self, metrics: _InFlightMetric) -> None:
- """Gets called when processing in flight metrics"""
- assert self.start is not None
- duration = self.clock.time() - self.start
- metrics.real_time_max = max(metrics.real_time_max, duration)
- metrics.real_time_sum += duration
- # TODO: Add other in flight metrics.
- class DynamicCollectorRegistry(CollectorRegistry):
- """
- Custom Prometheus Collector registry that calls a hook first, allowing you
- to update metrics on-demand.
- Don't forget to register this registry with the main registry!
- """
- def __init__(self) -> None:
- super().__init__()
- self._pre_update_hooks: Dict[str, Callable[[], None]] = {}
- def collect(self) -> Generator[Metric, None, None]:
- """
- Collects metrics, calling pre-update hooks first.
- """
- for pre_update_hook in self._pre_update_hooks.values():
- pre_update_hook()
- yield from super().collect()
- def register_hook(self, metric_name: str, hook: Callable[[], None]) -> None:
- """
- Registers a hook that is called before metric collection.
- """
- self._pre_update_hooks[metric_name] = hook
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