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',
])
|
