forked from MirrorHub/synapse
report metrics on number of cache evictions
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77c0629ebc
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bc496df192
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@ -193,7 +193,9 @@ class DistributionMetric(object):
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class CacheMetric(object):
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__slots__ = ("name", "cache_name", "hits", "misses", "size_callback")
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__slots__ = (
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"name", "cache_name", "hits", "misses", "evicted_size", "size_callback",
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)
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def __init__(self, name, size_callback, cache_name):
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self.name = name
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@ -201,6 +203,7 @@ class CacheMetric(object):
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self.hits = 0
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self.misses = 0
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self.evicted_size = 0
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self.size_callback = size_callback
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@ -210,6 +213,9 @@ class CacheMetric(object):
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def inc_misses(self):
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self.misses += 1
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def inc_evictions(self, size=1):
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self.evicted_size += size
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def render(self):
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size = self.size_callback()
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hits = self.hits
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@ -219,6 +225,9 @@ class CacheMetric(object):
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"""%s:hits{name="%s"} %d""" % (self.name, self.cache_name, hits),
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"""%s:total{name="%s"} %d""" % (self.name, self.cache_name, total),
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"""%s:size{name="%s"} %d""" % (self.name, self.cache_name, size),
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"""%s:evicted_size{name="%s"} %d""" % (
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self.name, self.cache_name, self.evicted_size
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),
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]
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@ -75,6 +75,7 @@ class Cache(object):
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self.cache = LruCache(
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max_size=max_entries, keylen=keylen, cache_type=cache_type,
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size_callback=(lambda d: len(d)) if iterable else None,
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evicted_callback=self._on_evicted,
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)
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self.name = name
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@ -83,6 +84,9 @@ class Cache(object):
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self.thread = None
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self.metrics = register_cache(name, self.cache)
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def _on_evicted(self, evicted_count):
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self.metrics.inc_evictions(evicted_count)
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def check_thread(self):
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expected_thread = self.thread
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if expected_thread is None:
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@ -79,7 +79,11 @@ class ExpiringCache(object):
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while self._max_len and len(self) > self._max_len:
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_key, value = self._cache.popitem(last=False)
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if self.iterable:
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self._size_estimate -= len(value.value)
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removed_len = len(value.value)
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self.metrics.inc_evictions(removed_len)
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self._size_estimate -= removed_len
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else:
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self.metrics.inc_evictions()
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def __getitem__(self, key):
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try:
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@ -49,7 +49,24 @@ class LruCache(object):
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Can also set callbacks on objects when getting/setting which are fired
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when that key gets invalidated/evicted.
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"""
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def __init__(self, max_size, keylen=1, cache_type=dict, size_callback=None):
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def __init__(self, max_size, keylen=1, cache_type=dict, size_callback=None,
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evicted_callback=None):
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"""
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Args:
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max_size (int):
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keylen (int):
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cache_type (type):
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type of underlying cache to be used. Typically one of dict
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or TreeCache.
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size_callback (func(V) -> int | None):
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evicted_callback (func(int)|None):
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if not None, called on eviction with the size of the evicted
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entry
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"""
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cache = cache_type()
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self.cache = cache # Used for introspection.
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list_root = _Node(None, None, None, None)
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@ -61,8 +78,10 @@ class LruCache(object):
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def evict():
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while cache_len() > max_size:
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todelete = list_root.prev_node
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delete_node(todelete)
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evicted_len = delete_node(todelete)
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cache.pop(todelete.key, None)
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if evicted_callback:
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evicted_callback(evicted_len)
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def synchronized(f):
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@wraps(f)
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@ -111,12 +130,15 @@ class LruCache(object):
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prev_node.next_node = next_node
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next_node.prev_node = prev_node
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deleted_len = 1
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if size_callback:
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cached_cache_len[0] -= size_callback(node.value)
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deleted_len = size_callback(node.value)
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cached_cache_len[0] -= deleted_len
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for cb in node.callbacks:
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cb()
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node.callbacks.clear()
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return deleted_len
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@synchronized
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def cache_get(key, default=None, callbacks=[]):
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@ -141,6 +141,7 @@ class CacheMetricTestCase(unittest.TestCase):
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'cache:hits{name="cache_name"} 0',
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'cache:total{name="cache_name"} 0',
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'cache:size{name="cache_name"} 0',
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'cache:evicted_size{name="cache_name"} 0',
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])
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metric.inc_misses()
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@ -150,6 +151,7 @@ class CacheMetricTestCase(unittest.TestCase):
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'cache:hits{name="cache_name"} 0',
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'cache:total{name="cache_name"} 1',
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'cache:size{name="cache_name"} 1',
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'cache:evicted_size{name="cache_name"} 0',
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])
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metric.inc_hits()
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@ -158,4 +160,14 @@ class CacheMetricTestCase(unittest.TestCase):
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'cache:hits{name="cache_name"} 1',
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'cache:total{name="cache_name"} 2',
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'cache:size{name="cache_name"} 1',
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'cache:evicted_size{name="cache_name"} 0',
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])
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metric.inc_evictions(2)
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self.assertEquals(metric.render(), [
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'cache:hits{name="cache_name"} 1',
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'cache:total{name="cache_name"} 2',
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'cache:size{name="cache_name"} 1',
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'cache:evicted_size{name="cache_name"} 2',
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])
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