From bc496df192fa20dee933590d5f21a3425388c0d7 Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Thu, 1 Feb 2018 17:57:51 +0000 Subject: report metrics on number of cache evictions --- synapse/metrics/metric.py | 11 ++++++++++- synapse/util/caches/descriptors.py | 4 ++++ synapse/util/caches/expiringcache.py | 6 +++++- synapse/util/caches/lrucache.py | 28 +++++++++++++++++++++++++--- tests/metrics/test_metric.py | 12 ++++++++++++ 5 files changed, 56 insertions(+), 5 deletions(-) diff --git a/synapse/metrics/metric.py b/synapse/metrics/metric.py index 1e783e5ff4..ff5aa8c0e1 100644 --- a/synapse/metrics/metric.py +++ b/synapse/metrics/metric.py @@ -193,7 +193,9 @@ class DistributionMetric(object): class CacheMetric(object): - __slots__ = ("name", "cache_name", "hits", "misses", "size_callback") + __slots__ = ( + "name", "cache_name", "hits", "misses", "evicted_size", "size_callback", + ) def __init__(self, name, size_callback, cache_name): self.name = name @@ -201,6 +203,7 @@ class CacheMetric(object): self.hits = 0 self.misses = 0 + self.evicted_size = 0 self.size_callback = size_callback @@ -210,6 +213,9 @@ class CacheMetric(object): def inc_misses(self): self.misses += 1 + def inc_evictions(self, size=1): + self.evicted_size += size + def render(self): size = self.size_callback() hits = self.hits @@ -219,6 +225,9 @@ class CacheMetric(object): """%s:hits{name="%s"} %d""" % (self.name, self.cache_name, hits), """%s:total{name="%s"} %d""" % (self.name, self.cache_name, total), """%s:size{name="%s"} %d""" % (self.name, self.cache_name, size), + """%s:evicted_size{name="%s"} %d""" % ( + self.name, self.cache_name, self.evicted_size + ), ] diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index af65bfe7b8..bf3a66eae4 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -75,6 +75,7 @@ class Cache(object): self.cache = LruCache( max_size=max_entries, keylen=keylen, cache_type=cache_type, size_callback=(lambda d: len(d)) if iterable else None, + evicted_callback=self._on_evicted, ) self.name = name @@ -83,6 +84,9 @@ class Cache(object): self.thread = None self.metrics = register_cache(name, self.cache) + def _on_evicted(self, evicted_count): + self.metrics.inc_evictions(evicted_count) + def check_thread(self): expected_thread = self.thread if expected_thread is None: diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py index 6ad53a6390..0aa103eecb 100644 --- a/synapse/util/caches/expiringcache.py +++ b/synapse/util/caches/expiringcache.py @@ -79,7 +79,11 @@ class ExpiringCache(object): while self._max_len and len(self) > self._max_len: _key, value = self._cache.popitem(last=False) if self.iterable: - self._size_estimate -= len(value.value) + removed_len = len(value.value) + self.metrics.inc_evictions(removed_len) + self._size_estimate -= removed_len + else: + self.metrics.inc_evictions() def __getitem__(self, key): try: diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py index cf5fbb679c..f088dd430e 100644 --- a/synapse/util/caches/lrucache.py +++ b/synapse/util/caches/lrucache.py @@ -49,7 +49,24 @@ class LruCache(object): Can also set callbacks on objects when getting/setting which are fired when that key gets invalidated/evicted. """ - def __init__(self, max_size, keylen=1, cache_type=dict, size_callback=None): + def __init__(self, max_size, keylen=1, cache_type=dict, size_callback=None, + evicted_callback=None): + """ + Args: + max_size (int): + + keylen (int): + + cache_type (type): + type of underlying cache to be used. Typically one of dict + or TreeCache. + + size_callback (func(V) -> int | None): + + evicted_callback (func(int)|None): + if not None, called on eviction with the size of the evicted + entry + """ cache = cache_type() self.cache = cache # Used for introspection. list_root = _Node(None, None, None, None) @@ -61,8 +78,10 @@ class LruCache(object): def evict(): while cache_len() > max_size: todelete = list_root.prev_node - delete_node(todelete) + evicted_len = delete_node(todelete) cache.pop(todelete.key, None) + if evicted_callback: + evicted_callback(evicted_len) def synchronized(f): @wraps(f) @@ -111,12 +130,15 @@ class LruCache(object): prev_node.next_node = next_node next_node.prev_node = prev_node + deleted_len = 1 if size_callback: - cached_cache_len[0] -= size_callback(node.value) + deleted_len = size_callback(node.value) + cached_cache_len[0] -= deleted_len for cb in node.callbacks: cb() node.callbacks.clear() + return deleted_len @synchronized def cache_get(key, default=None, callbacks=[]): diff --git a/tests/metrics/test_metric.py b/tests/metrics/test_metric.py index f85455a5af..39bde6e3f8 100644 --- a/tests/metrics/test_metric.py +++ b/tests/metrics/test_metric.py @@ -141,6 +141,7 @@ class CacheMetricTestCase(unittest.TestCase): 'cache:hits{name="cache_name"} 0', 'cache:total{name="cache_name"} 0', 'cache:size{name="cache_name"} 0', + 'cache:evicted_size{name="cache_name"} 0', ]) metric.inc_misses() @@ -150,6 +151,7 @@ class CacheMetricTestCase(unittest.TestCase): 'cache:hits{name="cache_name"} 0', 'cache:total{name="cache_name"} 1', 'cache:size{name="cache_name"} 1', + 'cache:evicted_size{name="cache_name"} 0', ]) metric.inc_hits() @@ -158,4 +160,14 @@ class CacheMetricTestCase(unittest.TestCase): 'cache:hits{name="cache_name"} 1', 'cache:total{name="cache_name"} 2', 'cache:size{name="cache_name"} 1', + 'cache:evicted_size{name="cache_name"} 0', + ]) + + metric.inc_evictions(2) + + self.assertEquals(metric.render(), [ + 'cache:hits{name="cache_name"} 1', + 'cache:total{name="cache_name"} 2', + 'cache:size{name="cache_name"} 1', + 'cache:evicted_size{name="cache_name"} 2', ]) -- cgit 1.4.1