diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 8271229015..b50e3503f0 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -1,5 +1,6 @@
# -*- coding: utf-8 -*-
# Copyright 2015, 2016 OpenMarket Ltd
+# Copyright 2019 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.
@@ -51,7 +52,19 @@ response_cache_evicted = Gauge(
response_cache_total = Gauge("synapse_util_caches_response_cache:total", "", ["name"])
-def register_cache(cache_type, cache_name, cache):
+def register_cache(cache_type, cache_name, cache, collect_callback=None):
+ """Register a cache object for metric collection.
+
+ Args:
+ cache_type (str):
+ cache_name (str): name of the cache
+ cache (object): cache itself
+ collect_callback (callable|None): if not None, a function which is called during
+ metric collection to update additional metrics.
+
+ Returns:
+ CacheMetric: an object which provides inc_{hits,misses,evictions} methods
+ """
# Check if the metric is already registered. Unregister it, if so.
# This usually happens during tests, as at runtime these caches are
@@ -90,6 +103,8 @@ def register_cache(cache_type, cache_name, cache):
cache_hits.labels(cache_name).set(self.hits)
cache_evicted.labels(cache_name).set(self.evicted_size)
cache_total.labels(cache_name).set(self.hits + self.misses)
+ if collect_callback:
+ collect_callback()
except Exception as e:
logger.warn("Error calculating metrics for %s: %s", cache_name, e)
raise
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index a1acacbde9..7e69cf55fb 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -22,6 +22,8 @@ from collections import namedtuple
import six
from six import itervalues, string_types
+from prometheus_client import Gauge
+
from twisted.internet import defer
from synapse.logging.context import make_deferred_yieldable, preserve_fn
@@ -37,6 +39,12 @@ from . import register_cache
logger = logging.getLogger(__name__)
+cache_pending_metric = Gauge(
+ "synapse_util_caches_cache_pending",
+ "Number of lookups currently pending for this cache",
+ ["name"],
+)
+
_CacheSentinel = object()
@@ -82,11 +90,19 @@ class Cache(object):
self.name = name
self.keylen = keylen
self.thread = None
- self.metrics = register_cache("cache", name, self.cache)
+ self.metrics = register_cache(
+ "cache",
+ name,
+ self.cache,
+ collect_callback=self._metrics_collection_callback,
+ )
def _on_evicted(self, evicted_count):
self.metrics.inc_evictions(evicted_count)
+ def _metrics_collection_callback(self):
+ cache_pending_metric.labels(self.name).set(len(self._pending_deferred_cache))
+
def check_thread(self):
expected_thread = self.thread
if expected_thread is None:
|
