anonymousland-synapse/synapse/util/caches/treecache.py
Erik Johnston f85b6ca494 Speed up cache size calculation
Instead of calculating the size of the cache repeatedly, which can take
a long time now that it can use a callback, instead cache the size and
update that on insertion and deletion.

This requires changing the cache descriptors to have two caches, one for
pending deferreds and the other for the actual values. There's no reason
to evict from the pending deferreds as they won't take up any more
memory.
2017-01-17 11:18:13 +00:00

108 lines
2.6 KiB
Python

SENTINEL = object()
class TreeCache(object):
"""
Tree-based backing store for LruCache. Allows subtrees of data to be deleted
efficiently.
Keys must be tuples.
"""
def __init__(self):
self.size = 0
self.root = {}
def __setitem__(self, key, value):
return self.set(key, value)
def __contains__(self, key):
return self.get(key, SENTINEL) is not SENTINEL
def set(self, key, value):
node = self.root
for k in key[:-1]:
node = node.setdefault(k, {})
node[key[-1]] = _Entry(value)
self.size += 1
def get(self, key, default=None):
node = self.root
for k in key[:-1]:
node = node.get(k, None)
if node is None:
return default
return node.get(key[-1], _Entry(default)).value
def clear(self):
self.size = 0
self.root = {}
def pop(self, key, default=None):
nodes = []
node = self.root
for k in key[:-1]:
node = node.get(k, None)
nodes.append(node) # don't add the root node
if node is None:
return default
popped = node.pop(key[-1], SENTINEL)
if popped is SENTINEL:
return default
node_and_keys = zip(nodes, key)
node_and_keys.reverse()
node_and_keys.append((self.root, None))
for i in range(len(node_and_keys) - 1):
n, k = node_and_keys[i]
if n:
break
node_and_keys[i + 1][0].pop(k)
popped, cnt = _strip_and_count_entires(popped)
self.size -= cnt
return popped
def values(self):
return list(popped_to_iterator(self.root))
def __len__(self):
return self.size
def popped_to_iterator(d):
if isinstance(d, dict):
for value_d in d.itervalues():
for value in popped_to_iterator(value_d):
yield value
else:
if isinstance(d, _Entry):
yield d.value
else:
yield d
class _Entry(object):
__slots__ = ["value"]
def __init__(self, value):
self.value = value
def _strip_and_count_entires(d):
"""Takes an _Entry or dict with leaves of _Entry's, and either returns the
value or a dictionary with _Entry's replaced by their values.
Also returns the count of _Entry's
"""
if isinstance(d, dict):
cnt = 0
for key, value in d.items():
v, n = _strip_and_count_entires(value)
d[key] = v
cnt += n
return d, cnt
else:
return d.value, 1