Extensions Docs Server: Efficient MemcacheFileSystem

chrome/common/extensions/docs/server2/subversion_file_system.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 re
 import xml.dom.minidom as xml
+from xml.parsers.expat import ExpatError
 
 import file_system
 from future import Future
 
 class SubversionFileSystem(file_system.FileSystem):
   """Class to fetch resources from src.chromium.org.
   """
-  def __init__(self, fetcher):
+  def __init__(self, fetcher, stat_fetcher):
     self._fetcher = fetcher
+    self._stat_fetcher = stat_fetcher
 
   def Read(self, paths, binary=False):
     return Future(delegate=_AsyncFetchFuture(paths, self._fetcher, binary))
 
+  def _ParseHTML(self, html):
+    """Unfortunately, the viewvc page has a stray </div> tag, so this takes care
+    of all mismatched tags.
+    """
+    try:
+      return xml.parseString(html)
+    except ExpatError as e:
+      new_html = []
+      for lineno, line in enumerate(html.split('\n')):
+        if e.lineno != lineno + 1:
+          new_html.append(line)
+      return self._ParseHTML('\n'.join(new_html))
+
+  def _CreateStatInfo(self, html):
+    dom = self._ParseHTML(html)
+    # Brace yourself, this is about to get ugly. The page returned from viewvc
+    # was not the prettiest.
+    tds = dom.getElementsByTagName('td')
+    a_list = []
+    found = False
+    dir_revision = None
+    for td in tds:
+      if found:
+        dir_revision = td.getElementsByTagName('a')[0].firstChild.nodeValue
+        found = False
+      a_list.extend(td.getElementsByTagName('a'))
+      if (td.firstChild is not None and
+          td.firstChild.nodeValue == 'Directory revision:'):
+        found = True
+    child_revisions = {}
+    for i, a in enumerate(a_list):
+      try:
+        next_a = a_list[i + 1]
+      except IndexError:
+        break

[not at google - send to devlin, 2012/08/13 23:02:14]

Exceptions aren't a good way of signaling control flow.

if i + 1 < len(a_list):
  break

would be better.

[not at google - send to devlin, 2012/08/14 04:00:08]

and by that I mean >= not <

[cduvall, 2012/08/14 18:15:00]

Done.

+      name = a.getAttribute('name')
+      if name:
+        rev = next_a.getElementsByTagName('strong')[0]
+        if 'file' in next_a.getAttribute('title'):
+          child_revisions[name] = rev.firstChild.nodeValue
+        else:
+          child_revisions[name + '/'] = rev.firstChild.nodeValue
+    return self.StatInfo(dir_revision, child_revisions)
+
   def Stat(self, path):
     directory = path.rsplit('/', 1)[0]
-    result = self._fetcher.Fetch(directory + '/')
+    result = self._stat_fetcher.Fetch(directory + '/')
     if result.status_code == 404:
       raise file_system.FileNotFoundError(path)
-    return self.StatInfo(int(re.search('([0-9]+)', result.content).group(0)))
+    stat_info = self._CreateStatInfo(result.content)
+    if not path.endswith('/'):
+      filename = path.rsplit('/', 1)[-1]
+      if filename not in stat_info.child_versions:
+        raise file_system.FileNotFoundError(path)
+      stat_info.version = stat_info.child_versions[filename]
+    return stat_info
 
 class _AsyncFetchFuture(object):
   def __init__(self, paths, fetcher, binary):
     # A list of tuples of the form (path, Future).
     self._fetches = []
     self._value = {}
     self._error = None
     self._fetches = [(path, fetcher.FetchAsync(path)) for path in paths]
     self._binary = binary
 
@@ skipping 12 matching lines @@
       elif path.endswith('/'):
         self._value[path] = self._ListDir(result.content)
       elif not self._binary:
         self._value[path] = file_system._ProcessFileData(result.content, path)
       else:
         self._value[path] = result.content
     if self._error is not None:
       raise self._error
     return self._value