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Make LruCache use a dedicated _Node class

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This commit is contained in:
Erik Johnston 2016-03-22 16:06:21 +00:00
parent 99f929f36b
commit c4a8cbd15a
1 changed files with 41 additions and 32 deletions
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73
synapse/util/caches/lrucache.py
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@ -29,6 +29,16 @@ def enumerate_leaves(node, depth):
yield m
class _Node(object):
__slots__ = ["prev_node", "next_node", "key", "value"]
def __init__(self, prev_node, next_node, key, value):
self.prev_node = prev_node
self.next_node = next_node
self.key = key
self.value = value
class LruCache(object):
"""
Least-recently-used cache.
@ -38,10 +48,9 @@ class LruCache(object):
def __init__(self, max_size, keylen=1, cache_type=dict):
cache = cache_type()
self.cache = cache # Used for introspection.
list_root = []
list_root[:] = [list_root, list_root, None, None]
PREV, NEXT, KEY, VALUE = 0, 1, 2, 3
list_root = _Node(None, None, None, None)
list_root.next_node = list_root
list_root.prev_node = list_root
lock = threading.Lock()
@ -55,36 +64,36 @@ class LruCache(object):
def add_node(key, value):
prev_node = list_root
next_node = prev_node[NEXT]
node = [prev_node, next_node, key, value]
prev_node[NEXT] = node
next_node[PREV] = node
next_node = prev_node.next_node
node = _Node(prev_node, next_node, key, value)
prev_node.next_node = node
next_node.prev_node = node
cache[key] = node
def move_node_to_front(node):
prev_node = node[PREV]
next_node = node[NEXT]
prev_node[NEXT] = next_node
next_node[PREV] = prev_node
prev_node = node.prev_node
next_node = node.next_node
prev_node.next_node = next_node
next_node.prev_node = prev_node
prev_node = list_root
next_node = prev_node[NEXT]
node[PREV] = prev_node
node[NEXT] = next_node
prev_node[NEXT] = node
next_node[PREV] = node
next_node = prev_node.next_node
node.prev_node = prev_node
node.next_node = next_node
prev_node.next_node = node
next_node.prev_node = node
def delete_node(node):
prev_node = node[PREV]
next_node = node[NEXT]
prev_node[NEXT] = next_node
next_node[PREV] = prev_node
prev_node = node.prev_node
next_node = node.next_node
prev_node.next_node = next_node
next_node.prev_node = prev_node
@synchronized
def cache_get(key, default=None):
node = cache.get(key, None)
if node is not None:
move_node_to_front(node)
return node[VALUE]
return node.value
else:
return default
@ -93,25 +102,25 @@ class LruCache(object):
node = cache.get(key, None)
if node is not None:
move_node_to_front(node)
node[VALUE] = value
node.value = value
else:
add_node(key, value)
if len(cache) > max_size:
todelete = list_root[PREV]
todelete = list_root.prev_node
delete_node(todelete)
cache.pop(todelete[KEY], None)
cache.pop(todelete.key, None)
@synchronized
def cache_set_default(key, value):
node = cache.get(key, None)
if node is not None:
return node[VALUE]
return node.value
else:
add_node(key, value)
if len(cache) > max_size:
todelete = list_root[PREV]
todelete = list_root.prev_node
delete_node(todelete)
cache.pop(todelete[KEY], None)
cache.pop(todelete.key, None)
return value
@synchronized
@ -119,8 +128,8 @@ class LruCache(object):
node = cache.get(key, None)
if node:
delete_node(node)
cache.pop(node[KEY], None)
return node[VALUE]
cache.pop(node.key, None)
return node.value
else:
return default
@ -137,8 +146,8 @@ class LruCache(object):
@synchronized
def cache_clear():
list_root[NEXT] = list_root
list_root[PREV] = list_root
list_root.next_node = list_root
list_root.prev_node = list_root
cache.clear()
@synchronized