Dynamically generate a heading for Extension Docs API pages

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

+# Copyright (c) 2013 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 json
+import os
+
+from appengine_url_fetcher import AppEngineUrlFetcher
+from caching_file_system import CachingFileSystem
+from compiled_file_system import CompiledFileSystem
+from object_store_creator import ObjectStoreCreator
+from subversion_file_system import SubversionFileSystem
+import svn_constants
+import third_party.json_schema_compiler.model as model
+import url_constants
+

[epeterson, 2013/04/17 03:38:50]

Removed the [huge] dependency on api_data_source for generating availability.
availability_data_source takes care of it now.

+class AvailabilityDataSource(object):
+  '''Uses API data sources generated by a ChromeVersionDataSource in order to
+  search the filesystem for the earliest existence of a specified API throughout
+  the different versions of Chrome; this constitutes an API's availability.
+  '''
+  class Factory(object):
+    def __init__(self, chrome_version_utility, svn_file_system=None):
+      self._chrome_version_utility = chrome_version_utility
+      self._object_store = ObjectStoreCreator(AvailabilityDataSource).Create()
+
+      # The |svn_file_system| will only be none for testing.
+      if svn_file_system is not None:
+        json_string = svn_file_system.ReadSingle('%s/api_availabilities.json'
+                                                 % svn_constants.JSON_PATH)
+        self._existing_availabilities = json.loads(json_string)
+

[epeterson, 2013/04/17 03:38:50]

This hasn't been tested on the appengine, because the new .json file is only
available locally so far. It definitely works while running preview.py, though

+    def Create(self):
+      return AvailabilityDataSource(self._chrome_version_utility,
+                                    self._object_store,
+                                    self._existing_availabilities)
+
+  def __init__(self,
+               chrome_version_utility,
+               object_store,
+               existing_availabilities):
+    self._chrome_version_utility = chrome_version_utility
+    self._object_store = object_store
+    self._existing_availabilities = existing_availabilities
+
+  def _CreateSvnFileSystemForBranch(self, branch):
+    '''Creates a file system tied to a a specific branch of the svn repository.
+    '''
+    if branch == 'trunk':
+      svn_url = '/'.join((url_constants.SVN_TRUNK_URL,
+                          'src',
+                          svn_constants.EXTENSIONS_PATH))
+    else:
+      svn_url = '/'.join((url_constants.SVN_BRANCH_URL,
+                          branch,
+                          'src',
+                          svn_constants.EXTENSIONS_PATH))
+    viewvc_url = svn_url.replace(url_constants.SVN_URL,
+                                 url_constants.VIEWVC_URL)
+
+    svn_file_system = CachingFileSystem(
+        SubversionFileSystem(AppEngineUrlFetcher(svn_url),
+                             AppEngineUrlFetcher(viewvc_url)),
+        ObjectStoreCreator.Factory(branch))
+    return svn_file_system
+
+  def _GetAllNames(self, base_dir, apis):
+    '''Returns unix_hacker_style names for all APIs currently available.
+    '''
+    return [
+      model.UnixName(os.path.splitext(api)[0])
+      for api in apis
+    ]
+
+  def _GetAsSubdirectory(self, name):
+    if name.startswith('experimental_'):
+      parts = name[len('experimental_'):].split('_', 1)
+      if len(parts) > 1:
+        parts[1] = 'experimental_%s' % parts[1]
+        return '/'.join(parts)
+      else:
+        return '%s/%s' % (parts[0], name)
+    return name.replace('_', '/', 1)
+
+  def _CheckApiExistence(self, api_name, version):
+    '''Finds a list of APIs that are present in the given |version|, and checks
+       to see whether or not |api_name| exists in that list.
+    '''
+    names = self._object_store.Get(version).Get()
+
+    if names is None:
+      svn_file_system = self._CreateSvnFileSystemForBranch(
+          self._chrome_version_utility.GetBranchNumberForVersion(version))
+      compiled_fs_factory = CompiledFileSystem.Factory(
+          svn_file_system,
+          ObjectStoreCreator.Factory())
+      names_cache = compiled_fs_factory.Create(self._GetAllNames,
+                                               AvailabilityDataSource)
+      names = names_cache.GetFromFileListing(svn_constants.API_PATH)

[epeterson, 2013/04/17 03:38:50]

Instead of trying to load every file and check for a FileNotFoundError, we now
just check the file names present in the api directory (and cache the names,
too). This is faster.

+      self._object_store.Set(version, names)
+    api_name = model.UnixName(api_name)
+    return api_name in names or self._GetAsSubdirectory(api_name) in names
+
+  def FindEarliestAvailability(self, api_name):
+    '''Searches in descending order through filesystem caches tied to specific
+    chrome version numbers and looks for the existence of a specified api,
+    |api_name|. When an api is not found, returns the previous version number
+    (the last known version where the api was found).
+    '''
+    availability = self._object_store.Get(api_name).Get()
+    if availability is not None:
+      return availability
+    elif availability is False:
+      return None
+
+    # Check for a predetermined availability for this API.
+    availability = self._existing_availabilities.get(api_name, None)
+    if availability is not None:
+      self._object_store.Set(api_name, availability)
+      return availability
+
+    # If the API isn't found in trunk, then it isn't currently available.
+    if not self._CheckApiExistence(api_name, 'trunk'):
+      self._object_store.Set(api_name, False)
+      return None
+
+    latest_version = int(self._chrome_version_utility.GetLatestVersionNumber())
+    version_int = latest_version
+    # Extension APIs are not present in the filesystem before version 18.
+    while version_int >= 18:
+      if not self._CheckApiExistence(api_name, str(version_int)):
+        break
+      version_int -= 1
+
+    version_int += 1
+    if version_int > latest_version:
+      availability = 'trunk'
+    else:
+      availability = str(version_int)
+
+    self._object_store.Set(api_name, availability)
+    return availability