mirror of
https://git.anonymousland.org/anonymousland/synapse-product.git
synced 2024-12-25 18:19:23 -05:00
c0df6bae06
`keylen` seems to be a thing that is frequently incorrectly set, and we don't really need it. The only time it was used was to figure out if we had removed a subtree in `del_multi`, which we can do better by changing `TreeCache.pop` to return a different type (`TreeCacheNode`). Commits should be independently reviewable.
142 lines
4.3 KiB
Python
142 lines
4.3 KiB
Python
# Copyright 2016-2021 The Matrix.org Foundation C.I.C.
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
# See the License for the specific language governing permissions and
|
|
# limitations under the License.
|
|
|
|
SENTINEL = object()
|
|
|
|
|
|
class TreeCacheNode(dict):
|
|
"""The type of nodes in our tree.
|
|
|
|
Has its own type so we can distinguish it from real dicts that are stored at the
|
|
leaves.
|
|
"""
|
|
|
|
pass
|
|
|
|
|
|
class TreeCache:
|
|
"""
|
|
Tree-based backing store for LruCache. Allows subtrees of data to be deleted
|
|
efficiently.
|
|
Keys must be tuples.
|
|
|
|
The data structure is a chain of TreeCacheNodes:
|
|
root = {key_1: {key_2: _value}}
|
|
"""
|
|
|
|
def __init__(self):
|
|
self.size = 0
|
|
self.root = TreeCacheNode()
|
|
|
|
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):
|
|
if isinstance(value, TreeCacheNode):
|
|
# this would mean we couldn't tell where our tree ended and the value
|
|
# started.
|
|
raise ValueError("Cannot store TreeCacheNodes in a TreeCache")
|
|
|
|
node = self.root
|
|
for k in key[:-1]:
|
|
next_node = node.get(k, SENTINEL)
|
|
if next_node is SENTINEL:
|
|
next_node = node[k] = TreeCacheNode()
|
|
elif not isinstance(next_node, TreeCacheNode):
|
|
# this suggests that the caller is not being consistent with its key
|
|
# length.
|
|
raise ValueError("value conflicts with an existing subtree")
|
|
node = next_node
|
|
|
|
node[key[-1]] = 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], default)
|
|
|
|
def clear(self):
|
|
self.size = 0
|
|
self.root = TreeCacheNode()
|
|
|
|
def pop(self, key, default=None):
|
|
"""Remove the given key, or subkey, from the cache
|
|
|
|
Args:
|
|
key: key or subkey to remove.
|
|
default: value to return if key is not found
|
|
|
|
Returns:
|
|
If the key is not found, 'default'. If the key is complete, the removed
|
|
value. If the key is partial, the TreeCacheNode corresponding to the part
|
|
of the tree that was removed.
|
|
"""
|
|
# a list of the nodes we have touched on the way down the tree
|
|
nodes = []
|
|
|
|
node = self.root
|
|
for k in key[:-1]:
|
|
node = node.get(k, None)
|
|
if node is None:
|
|
return default
|
|
if not isinstance(node, TreeCacheNode):
|
|
# we've gone off the end of the tree
|
|
raise ValueError("pop() key too long")
|
|
nodes.append(node) # don't add the root node
|
|
popped = node.pop(key[-1], SENTINEL)
|
|
if popped is SENTINEL:
|
|
return default
|
|
|
|
# working back up the tree, clear out any nodes that are now empty
|
|
node_and_keys = list(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
|
|
# found an empty node: remove it from its parent, and loop.
|
|
node_and_keys[i + 1][0].pop(k)
|
|
|
|
cnt = sum(1 for _ in iterate_tree_cache_entry(popped))
|
|
self.size -= cnt
|
|
return popped
|
|
|
|
def values(self):
|
|
return iterate_tree_cache_entry(self.root)
|
|
|
|
def __len__(self):
|
|
return self.size
|
|
|
|
|
|
def iterate_tree_cache_entry(d):
|
|
"""Helper function to iterate over the leaves of a tree, i.e. a dict of that
|
|
can contain dicts.
|
|
"""
|
|
if isinstance(d, TreeCacheNode):
|
|
for value_d in d.values():
|
|
for value in iterate_tree_cache_entry(value_d):
|
|
yield value
|
|
else:
|
|
yield d
|