Merge branch 'develop' into matthew/preview_urls

3 files changed, 144 insertions, 32 deletions

diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 1a14904194..d53569ca49 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -14,6 +14,10 @@
 # limitations under the License.
 
 import synapse.metrics
+from lrucache import LruCache
+import os
+
+CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.1))
 
 DEBUG_CACHES = False
 
@@ -25,3 +29,56 @@ cache_counter = metrics.register_cache(
     lambda: {(name,): len(caches_by_name[name]) for name in caches_by_name.keys()},
     labels=["name"],
 )
+
+_string_cache = LruCache(int(5000 * CACHE_SIZE_FACTOR))
+caches_by_name["string_cache"] = _string_cache
+
+
+KNOWN_KEYS = {
+    key: key for key in
+    (
+        "auth_events",
+        "content",
+        "depth",
+        "event_id",
+        "hashes",
+        "origin",
+        "origin_server_ts",
+        "prev_events",
+        "room_id",
+        "sender",
+        "signatures",
+        "state_key",
+        "type",
+        "unsigned",
+        "user_id",
+    )
+}
+
+
+def intern_string(string):
+    """Takes a (potentially) unicode string and interns using custom cache
+    """
+    return _string_cache.setdefault(string, string)
+
+
+def intern_dict(dictionary):
+    """Takes a dictionary and interns well known keys and their values
+    """
+    return {
+        KNOWN_KEYS.get(key, key): _intern_known_values(key, value)
+        for key, value in dictionary.items()
+    }
+
+
+def _intern_known_values(key, value):
+    intern_str_keys = ("event_id", "room_id")
+    intern_unicode_keys = ("sender", "user_id", "type", "state_key")
+
+    if key in intern_str_keys:
+        return intern(value.encode('ascii'))
+
+    if key in intern_unicode_keys:
+        return intern_string(value)
+
+    return value
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index f7423f2fab..f9df445a8d 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -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
diff --git a/synapse/util/caches/response_cache.py b/synapse/util/caches/response_cache.py
new file mode 100644
index 0000000000..be310ba320
--- /dev/null
+++ b/synapse/util/caches/response_cache.py
@@ -0,0 +1,46 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 OpenMarket Ltd
+#
+# 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.
+
+from synapse.util.async import ObservableDeferred
+
+
+class ResponseCache(object):
+    """
+    This caches a deferred response. Until the deferred completes it will be
+    returned from the cache. This means that if the client retries the request
+    while the response is still being computed, that original response will be
+    used rather than trying to compute a new response.
+    """
+
+    def __init__(self):
+        self.pending_result_cache = {}  # Requests that haven't finished yet.
+
+    def get(self, key):
+        result = self.pending_result_cache.get(key)
+        if result is not None:
+            return result.observe()
+        else:
+            return None
+
+    def set(self, key, deferred):
+        result = ObservableDeferred(deferred)
+        self.pending_result_cache[key] = result
+
+        def remove(r):
+            self.pending_result_cache.pop(key, None)
+            return r
+
+        result.addBoth(remove)
+        return result.observe()