Devserver: monitor the source code of server2 in svn. When it changes, pin the

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

Index: chrome/common/extensions/docs/server2/revision_pinner.py
diff --git a/chrome/common/extensions/docs/server2/revision_pinner.py b/chrome/common/extensions/docs/server2/revision_pinner.py
new file mode 100644
index 0000000000000000000000000000000000000000..808e5872503967f981346128c2e408f6e8df77cc
--- /dev/null
+++ b/chrome/common/extensions/docs/server2/revision_pinner.py
@@ -0,0 +1,126 @@
+# Copyright 2013 The Chromium Authors. All rights reserved.
+# Use of this server2 code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import logging
+from object_store_creator import ObjectStoreCreator
+import random
+
+class _Info(object):
+  '''Info about the revision pinning. Properties:
+  |server2_version| The last known version of server2 source.
+  |fs_version |     The current safe version of the file system. This isn't
+                    necessarily related to |server2_version|.
+  |pinned|          None if there is no pin. The password (string) to unpin it
+                    if it is pinned.
+  '''
+  def __init__(self, server2_version, root_version, pinned=None):
+    self.server2_version = server2_version
+    self.root_version = root_version
+    self.pinned = pinned
+
+# TODO(kalman): RevisionInfo? VersionInfo? VersionPinner?
+class RevisionPinner(object):
+  '''Tracks the subversion version that each branch is pinned to.
+
+  Responsible for pausing branches when any of the directories that server2
+  server2 is pulled from changes.
+
+  Generates and exposes a method to unpin those values.
+  '''
+  @staticmethod
+  def CreateForSubversion(branch,
+                          svn_file_system,
+                          object_store_creator_factory):
+    server2_dirs = [
+        'chrome/common/extensions/docs/server2/',
+        'third_party/handlebar/',
+        'tools/json_schema_compiler/'
+        'tools/json_schema_eater/'
+    ]
+    return RevisionPinner(branch,
+                          svn_file_system,
+                          object_store_creator_factory,
+                          server2_dirs)
+
+  def __init__(self,
+               branch,
+               file_system,
+               object_store_creator_factory,
+               server2_dirs):
+    self._branch = branch
+    self._file_system = file_system
+    self._object_store = (
+        object_store_creator_factory.Create(RevisionPinner).Create(
+            category=file_system.GetName()))
+    self._server2_dirs = server2_dirs
+
+  def Update(self):
+    '''Checks to see whether there have been any changes to the server2 dirs.
+    If so, pin at the current version with an option to unpin.
+    Otherwise, bump the version.
+    '''
+    server2_version = max(
+        int(self._file_system.Stat(server2_dir).version)
+        for server2_dir in self._server2_dirs)
+    root_version = int(self._file_system.Stat('/').version)
+    logging.info('server2_version: %s, root_version: %s' % (
+        server2_version, root_version))
+
+    info = self._object_store.Get('info')
+
+    if info is None:
+      logging.info('No existing info')
+      info = _Info(server2_version, root_version)
+    elif info.pinned:
+      logging.info('Still pinned at %s' % info.root_version)
+      info = _Info(server2_version, info.root_version, pinned=info.pinned)
+    elif server2_version <= info.server2_version:
+      logging.info('No change in server2 version')
+      # Ok, the version probably isn't going to *regress* but be safe anyway.
+      # Who knows what might happen to SVN.
+      info = _Info(server2_version, root_version)
+    else:
+      logging.info('server2 version increased from %s to %s' % (
+          server2_version, info.server2_version))
+      # New version of server2! Pin it: root_version doesn't increase, and
+      # the pin bit is flipped.
+      password = self._GeneratePassword()
+      info = _Info(server2_version, info.root_version, pinned=password)
+      self._NotifyPinned(info.root_version, password)
+
+    self._object_store.Set('info', info)
+
+  def _GeneratePassword(self):
+    # TODO(kalman): generate a prettier password using full alphanumerics.
+    return ''.join(map(str, random.sample(xrange(100, 999), 10)))
+
+  def _OnPinned(self, revision, pinned):
+    '''Called when the file system is pinned at |revision| using |password|.
+    Set up a way to unpin it: send email to kalman@ with an unlock pin.
+    '''
+    logging.warning('PINNED AT %s' % self._GenerateUnlockURL(pinned))
+
+  def _GenerateUnlockURL(self, pinned):
+    assert pinned
+    # TODO(kalman): Include hostname.
+    return '/_unpin/%s/%s' % (branch, pinned)
+
+  def GetRevision(self):
+    '''Gets the revision that |file_system| is currently pinned at.
+    '''
+    return self._object_store.Get('info').Get().root_version
+
+  def GetPinned(self):
+    '''Gets the pinned password if |file_system| is pinned, None if not.
+    '''
+    return self._object_store.Get('info').Get().pinned
+
+  def Unpin(self, password):
+    '''Unpins using |password|. Returns true if successful, false if not.
+    '''
+    if self.GetPinned() != password:
+      return False
+    self._object_store.Del('info')
+    self.Update()
+    return True