From 766526e1142e7ad0ffb43bd075b0ff2d6265e4cb Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 29 Jan 2016 10:11:21 +0000
Subject: [PATCH] Make TreeCache keep track of its own size.

---
 synapse/util/caches/lrucache.py  | 9 +++------
 synapse/util/caches/treecache.py | 7 +++++++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index 5182cadb9e..ca9ffdf1b4 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -38,7 +38,6 @@ class LruCache(object):
     def __init__(self, max_size, keylen=1, cache_type=dict):
         cache = cache_type()
         self.cache = cache  # Used for introspection.
-        self.size = 0
         list_root = []
         list_root[:] = [list_root, list_root, None, None]
 
@@ -61,7 +60,6 @@ class LruCache(object):
             prev_node[NEXT] = node
             next_node[PREV] = node
             cache[key] = node
-            self.size += 1
 
         def move_node_to_front(node):
             prev_node = node[PREV]
@@ -80,7 +78,6 @@ class LruCache(object):
             next_node = node[NEXT]
             prev_node[NEXT] = next_node
             next_node[PREV] = prev_node
-            self.size -= 1
 
         @synchronized
         def cache_get(key, default=None):
@@ -99,7 +96,7 @@ class LruCache(object):
                 node[VALUE] = value
             else:
                 add_node(key, value)
-                if self.size > max_size:
+                if len(cache) > max_size:
                     todelete = list_root[PREV]
                     delete_node(todelete)
                     cache.pop(todelete[KEY], None)
@@ -111,7 +108,7 @@ class LruCache(object):
                 return node[VALUE]
             else:
                 add_node(key, value)
-                if self.size > max_size:
+                if len(cache) > max_size:
                     todelete = list_root[PREV]
                     delete_node(todelete)
                     cache.pop(todelete[KEY], None)
@@ -147,7 +144,7 @@ class LruCache(object):
 
         @synchronized
         def cache_len():
-            return self.size
+            return len(cache)
 
         @synchronized
         def cache_contains(key):
diff --git a/synapse/util/caches/treecache.py b/synapse/util/caches/treecache.py
index 3b58860910..a29ea8144e 100644
--- a/synapse/util/caches/treecache.py
+++ b/synapse/util/caches/treecache.py
@@ -8,6 +8,7 @@ class TreeCache(object):
     Keys must be tuples.
     """
     def __init__(self):
+        self.size = 0
         self.root = {}
 
     def __setitem__(self, key, value):
@@ -21,6 +22,7 @@ class TreeCache(object):
         for k in key[:-1]:
             node = node.setdefault(k, {})
         node[key[-1]] = value
+        self.size += 1
 
     def get(self, key, default=None):
         node = self.root
@@ -31,6 +33,7 @@ class TreeCache(object):
         return node.get(key[-1], default)
 
     def clear(self):
+        self.size = 0
         self.root = {}
 
     def pop(self, key, default=None):
@@ -57,4 +60,8 @@ class TreeCache(object):
                 break
             node_and_keys[i+1][0].pop(k)
 
+        self.size -= 1
         return popped
+
+    def __len__(self):
+        return self.size