Docserver: Implement Cron for PathCanonicalizer.

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

Index: chrome/common/extensions/docs/server2/path_canonicalizer.py
diff --git a/chrome/common/extensions/docs/server2/path_canonicalizer.py b/chrome/common/extensions/docs/server2/path_canonicalizer.py
index fd95e9b71b32dca54d69b96648e067918216b2ad..1d8e3fc2995d767b000e2b1bd2ab12a39f79d3b9 100644
--- a/chrome/common/extensions/docs/server2/path_canonicalizer.py
+++ b/chrome/common/extensions/docs/server2/path_canonicalizer.py
@@ -5,6 +5,7 @@
 from collections import defaultdict
 import posixpath
 
+from future import Gettable, Future
 from path_util import SplitParent
 from special_paths import SITE_VERIFICATION_FILE
 
@@ -34,47 +35,51 @@ class PathCanonicalizer(object):
     self._strip_extensions = strip_extensions
 
   def _LoadCache(self):
-    cached = self._cache.GetMulti(('canonical_paths',
-                                   'simplified_paths_map')).Get()
-
-    # |canonical_paths| is the pre-calculated set of canonical paths.
-    # |simplified_paths_map| is a lazily populated mapping of simplified file
-    # names to a list of full paths that contain them. For example,
-    #  - browseraction: [extensions/browserAction.html]
-    #  - storage: [apps/storage.html, extensions/storage.html]
-    canonical_paths, simplified_paths_map = (
-        cached.get('canonical_paths'), cached.get('simplified_paths_map'))
-
-    if canonical_paths is None:
-      assert simplified_paths_map is None
-      canonical_paths = set()
-      simplified_paths_map = defaultdict(list)
-      for base, dirs, files in self._file_system.Walk(''):
-        for path in dirs + files:
-          path_without_ext, ext = posixpath.splitext(path)
-          canonical_path = posixpath.join(base, path_without_ext)
-          if (ext not in self._strip_extensions or
-              path == SITE_VERIFICATION_FILE):
-            canonical_path += ext
-          canonical_paths.add(canonical_path)
-          simplified_paths_map[_SimplifyFileName(path)].append(canonical_path)
-      # Store |simplified_paths_map| sorted. Ties in length are broken by taking
-      # the shortest, lexicographically smallest path.
-      for path_list in simplified_paths_map.itervalues():
-        path_list.sort(key=lambda p: (len(p), p))
-      self._cache.SetMulti({
-        'canonical_paths': canonical_paths,
-        'simplified_paths_map': simplified_paths_map,
-      })
-    else:
-      assert simplified_paths_map is not None
-
-    return canonical_paths, simplified_paths_map
+    cached_future = self._cache.GetMulti(('canonical_paths',
+                                          'simplified_paths_map'))
+
+    def resolve():
+      # |canonical_paths| is the pre-calculated set of canonical paths.
+      # |simplified_paths_map| is a lazily populated mapping of simplified file
+      # names to a list of full paths that contain them. For example,
+      #  - browseraction: [extensions/browserAction.html]
+      #  - storage: [apps/storage.html, extensions/storage.html]
+      cached = cached_future.Get()
+      canonical_paths, simplified_paths_map = (
+          cached.get('canonical_paths'), cached.get('simplified_paths_map'))
+
+      if canonical_paths is None:
+        assert simplified_paths_map is None
+        canonical_paths = set()
+        simplified_paths_map = defaultdict(list)
+        for base, dirs, files in self._file_system.Walk(''):
+          for path in dirs + files:
+            path_without_ext, ext = posixpath.splitext(path)
+            canonical_path = posixpath.join(base, path_without_ext)
+            if (ext not in self._strip_extensions or
+                path == SITE_VERIFICATION_FILE):
+              canonical_path += ext
+            canonical_paths.add(canonical_path)
+            simplified_paths_map[_SimplifyFileName(path)].append(canonical_path)
+        # Store |simplified_paths_map| sorted. Ties in length are broken by
+        # taking the shortest, lexicographically smallest path.
+        for path_list in simplified_paths_map.itervalues():
+          path_list.sort(key=lambda p: (len(p), p))
+        self._cache.SetMulti({
+          'canonical_paths': canonical_paths,
+          'simplified_paths_map': simplified_paths_map,
+        })
+      else:
+        assert simplified_paths_map is not None
+
+      return canonical_paths, simplified_paths_map
+
+    return Future(delegate=Gettable(resolve))
 
   def Canonicalize(self, path):
     '''Returns the canonical path for |path|.
     '''
-    canonical_paths, simplified_paths_map = self._LoadCache()
+    canonical_paths, simplified_paths_map = self._LoadCache().Get()
 
     # Path may already be the canonical path.
     if path in canonical_paths:
@@ -99,3 +104,6 @@ class PathCanonicalizer(object):
         max_prefix, max_prefix_length = path_for_file, prefix_length
 
     return max_prefix
+
+  def Cron(self):
+    return self._LoadCache()