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

   1 # Copyright 2013 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 from branch_utility import BranchUtility
   6 from commit_tracker import CommitTracker
   7 from compiled_file_system import CompiledFileSystem
   8 from environment import IsDevServer, IsReleaseServer
   9 from host_file_system_provider import HostFileSystemProvider
  10 from third_party.json_schema_compiler.memoize import memoize
  11 from render_servlet import RenderServlet
  12 from object_store_creator import ObjectStoreCreator
  13 from server_instance import ServerInstance
  14 from gcs_file_system_provider import CloudStorageFileSystemProvider
  15
  16
  17 class InstanceServletRenderServletDelegate(RenderServlet.Delegate):
  18   '''AppEngine instances should never need to call out to Gitiles. That should
  19   only ever be done by the cronjobs, which then write the result into
  20   DataStore, which is as far as instances look. To enable this, crons can pass
  21   a custom (presumably online) ServerInstance into Get().
  22
  23   Why? Gitiles is slow and a bit flaky. Refresh jobs failing is annoying but
  24   temporary. Instances failing affects users, and is really bad.
  25
  26   Anyway - to enforce this, we actually don't give instances access to
  27   Gitiles.  If anything is missing from datastore, it'll be a 404. If the
  28   cronjobs don't manage to catch everything - uhoh. On the other hand, we'll
  29   figure it out pretty soon, and it also means that legitimate 404s are caught
  30   before a round trip to Gitiles.
  31   '''
  32   def __init__(self, delegate):
  33     self._delegate = delegate
  34
  35   @memoize
  36   def CreateServerInstance(self):
  37     object_store_creator = ObjectStoreCreator(start_empty=False)
  38     branch_utility = self._delegate.CreateBranchUtility(object_store_creator)
  39     commit_tracker = CommitTracker(object_store_creator)
  40     # In production have offline=True so that we can catch cron errors. In
  41     # development it's annoying to have to run the cron job, so offline=False.
  42     # Note that offline=True if running on any appengine server due to
  43     # http://crbug.com/345361.
  44     host_file_system_provider = self._delegate.CreateHostFileSystemProvider(
  45         object_store_creator,
  46         offline=not (IsDevServer() or IsReleaseServer()),
  47         pinned_commit=commit_tracker.Get('master').Get(),
  48         cache_only=True)
  49     return ServerInstance(object_store_creator,
  50                           CompiledFileSystem.Factory(object_store_creator),
  51                           branch_utility,
  52                           host_file_system_provider,
  53                           CloudStorageFileSystemProvider(object_store_creator))
  54
  55 class InstanceServlet(object):
  56   '''Servlet for running on normal AppEngine instances.
  57   Create this via GetConstructor() so that cache state can be shared amongst
  58   them via the memoizing Delegate.
  59   '''
  60   class Delegate(object):
  61     '''Allow runtime dependencies to be overriden for testing.
  62     '''
  63     def CreateBranchUtility(self, object_store_creator):
  64       return BranchUtility.Create(object_store_creator)
  65
  66     def CreateHostFileSystemProvider(self, object_store_creator, **optargs):
  67       return HostFileSystemProvider(object_store_creator, **optargs)
  68
  69     def CreateGithubFileSystemProvider(self, object_store_creator):
  70       return GithubFileSystemProvider(object_store_creator)
  71
  72   @staticmethod
  73   def GetConstructor(delegate_for_test=None):
  74     render_servlet_delegate = InstanceServletRenderServletDelegate(
  75         delegate_for_test or InstanceServlet.Delegate())
  76     return lambda request: RenderServlet(request, render_servlet_delegate)
  77
  78   # NOTE: if this were a real Servlet it would implement a Get() method, but
  79   # GetConstructor returns an appropriate lambda function (Request -> Servlet).