Extension docs server: many changes to bring down the latency of the server,

chrome/common/extensions/docs/server2/appengine_wrappers.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This will attempt to import the actual App Engine modules, and if it fails,
 # they will be replaced with fake modules. This is useful during testing.
+
+import time
+
+class InMemoryMemcache(object):
+  """A memcache that stores items in memory instead of using the memcache
+  module.
+  """
+  class _CacheEntry(object):
+    def __init__(self, value, expire_time):
+      self.value = value
+      self._never_expires = (expire_time == 0)
+      self._expiry = time.time() + expire_time
+
+    def HasExpired(self):
+      if self._never_expires:
+        return False
+      return time.time() > self._expiry
+
+  def __init__(self):
+    self._cache = {}
+
+  def set(self, key, value, namespace, time=60):
+    if namespace not in self._cache:
+      self._cache[namespace] = {}
+    self._cache[namespace][key] = self._CacheEntry(value, time)
+
+  def get(self, key, namespace):
+    if namespace not in self._cache:
+      return None
+    cache_entry = self._cache[namespace].get(key, None)
+    if not cache_entry:
+      return None
+    if cache_entry.HasExpired():
+      self.delete(key, namespace)
+      return None
+    return cache_entry.value
+
+  def delete(self, key, namespace):
+    if namespace in self._cache:
+      self._cache[namespace].pop(key)
+
 try:
   import google.appengine.ext.blobstore as blobstore
   from google.appengine.ext.blobstore.blobstore import BlobReferenceProperty
   import google.appengine.ext.db as db
   import google.appengine.ext.webapp as webapp
   import google.appengine.api.files as files
-  import google.appengine.api.memcache as memcache
+  #import google.appengine.api.memcache as memcache
+  memcache = InMemoryMemcache()
   import google.appengine.api.urlfetch as urlfetch
 except ImportError:
   import re
 
   FAKE_URL_FETCHER_CONFIGURATION = None
 
   def ConfigureFakeUrlFetch(configuration):
     """|configuration| is a dictionary mapping strings to fake urlfetch classes.
     A fake urlfetch class just needs to have a fetch method. The keys of the
     dictionary are treated as regex, and they are matched with the URL to
@@ skipping 42 matching lines @@
       rpc.result = self.fetch(url)
   urlfetch = FakeUrlFetch()
 
   class NotImplemented(object):
     def __getattr__(self, attr):
       raise NotImplementedError()
 
   blobstore = NotImplemented()
   files = NotImplemented()
 
-  class InMemoryMemcache(object):
-    """A memcache that stores items in memory instead of using the memcache
-    module.
-    """
-    def __init__(self):
-      self._cache = {}
-
-    def set(self, key, value, namespace, time=60):
-      if namespace not in self._cache:
-        self._cache[namespace] = {}
-      self._cache[namespace][key] = value
-
-    def get(self, key, namespace):
-      if namespace not in self._cache:
-        return None
-      return self._cache[namespace].get(key, None)
-
-    def delete(self, key, namespace):
-      if namespace in self._cache:
-        self._cache[namespace].pop(key)
   memcache = InMemoryMemcache()
 
   # A fake webapp.RequestHandler class for Handler to extend.
   class webapp(object):
     class RequestHandler(object):
       def __init__(self, request, response):
         self.request = request
         self.response = response
 
       def redirect(self, path):
         self.request.path = path
 
   class _Db_Result(object):
     def get(self):
       return []
 
   class db(object):
     class StringProperty(object):
       pass
 
     class Model(object):
       @staticmethod
       def gql(*args):
         return _Db_Result()
 
   class BlobReferenceProperty(object):
     pass