Extensions Docs Server: Internal file system

chrome/common/extensions/docs/server2/fetcher_cache.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.
 
 import os
 import time
 
 class FetcherCache(object):

[not at google - send to devlin, 2012/07/18 10:39:15]

probably needs a rename/redocument.

also, s/fetcher/file_system/g

[cduvall, 2012/07/18 21:26:10]

Done.

   """A cache for fetcher objects.
   """
   class Builder(object):
     """A class to build a fetcher cache.
     """
     def __init__(self, fetcher, timeout_seconds):
       self._fetcher = fetcher
       self._timeout_seconds = timeout_seconds
 
     def build(self, populate_function):
       return FetcherCache(self._fetcher,
                           self._timeout_seconds,
                           populate_function)
 
   class _CacheEntry(object):

[not at google - send to devlin, 2012/07/18 10:39:15]

Here's the thing with this class now, by the way: the time-based caching is
redundant. And kinda of makes it... less good.

Basically, we should change the way this works, from having time-based cache
invalidation to querying Stat on the file system for whether it's expired.

[cduvall, 2012/07/18 21:26:10]

Done.

     def __init__(self, cache_data, expiry):
       self._cache_data = cache_data
       self._expiry = expiry
 
     def HasExpired(self):
       return time.time() > self._expiry
 
   def __init__(self, fetcher, timeout_seconds, populate_function):
     self._fetcher = fetcher
     self._timeout_seconds = timeout_seconds
     self._populate_function = populate_function
     self._cache = {}
 
-  def _Fetch(self, fetch_func, key, optional_params=None):
+  def _FetchFile(self, filename):
+    return self._fetcher.Read([filename])[filename]
+
+  def _RecursiveList(self, files):
+    all_files = files[:]
+    dirs = {}
+    for filename in files:
+      if filename.endswith('/'):
+        all_files.remove(filename)
+        dirs.update(self._fetcher.Read([filename]))
+    for dir_, files in dirs.iteritems():
+      all_files.extend(self._RecursiveList([dir_ + f for f in files.Get()]))
+    return all_files
+
+  def getFromFile(self, key):

[not at google - send to devlin, 2012/07/18 10:39:15]

document

and key -> path

[cduvall, 2012/07/18 21:26:10]

Done.

     if key in self._cache:
       if self._cache[key].HasExpired():
         self._cache.pop(key)
       else:
         return self._cache[key]._cache_data
-    if optional_params != None:
-      cache_data = fetch_func(key, optional_params).content
-    else:
-      cache_data = fetch_func(key).content
+    cache_data = self._FetchFile(key).Get()
     self._cache[key] = self._CacheEntry(self._populate_function(cache_data),
                                         time.time() + self._timeout_seconds)
     return self._cache[key]._cache_data
 
-  def getFromFileListing(self, path, recursive=False):
-    return self._Fetch(self._fetcher.ListDirectory, path, recursive)
-
-  def getFromFile(self, key):
-    return self._Fetch(self._fetcher.FetchResource, key)
+  def getFromFileListing(self, key):

[not at google - send to devlin, 2012/07/18 10:39:15]

document

also key -> path

btw this method should be tolerant to input that doesn't end in a / ... either
that or crash if it does. I prefer the former.

[cduvall, 2012/07/18 21:26:10]

Done.

+    if key in self._cache:
+      if self._cache[key].HasExpired():
+        self._cache.pop(key)
+      else:
+        return self._cache[key]._cache_data
+    cache_data = self._RecursiveList(
+        [key + f for f in self._FetchFile(key).Get()])
+    self._cache[key] = self._CacheEntry(self._populate_function(cache_data),
+                                        time.time() + self._timeout_seconds)
+    return self._cache[key]._cache_data