Move the Paths class to the util module.
#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""Allows applications to identify API outages and scheduled downtime.
Some examples:
def StoreUploadedProfileImage(self):
uploaded_image = self.request.get('img')
# If the images API is unavailable, we'll just skip the resize.
if CapabilitySet('images').is_enabled():
uploaded_image = images.resize(uploaded_image, 64, 64)
store(uploaded_image)
def RenderHTMLForm(self):
datastore_readonly = CapabilitySet('datastore_v3', capabilities=['write'])
if datastore_readonly.may_be_disabled_in(60):
# self.response.out('<p>Not accepting submissions right now: %s</p>' %
datastore_readonly.admin_message())
# ...render form with form elements disabled...
else:
# ...render form normally...
Individual API wrapper modules should expose CapabilitySet objects
for users rather than relying on users to create them. They may
also create convenience methods (e.g. db.IsReadOnly()) that delegate
to the relevant CapabilitySet.
Classes defined here:
CapabilitySet: encapsulates one or more capabilities, allows introspection.
UnknownCapabilityError: thrown when an unknown capability is requested.
"""
from google.appengine.api.capabilities import capability_service_pb
from google.appengine.base import capabilities_pb
from google.appengine.api import apiproxy_stub_map
IsEnabledRequest = capability_service_pb.IsEnabledRequest
IsEnabledResponse = capability_service_pb.IsEnabledResponse
CapabilityConfig = capabilities_pb.CapabilityConfig
class UnknownCapabilityError(Exception):
"""An unknown capability was requested."""
class CapabilitySet(object):
"""Encapsulates one or more capabilities.
Capabilities can either be named explicitly, or inferred from the
list of methods provided. If no capabilities or methods are
provided, this will check whether the entire package is enabled.
"""
def __init__(self, package, capabilities=None, methods=None,
stub_map=apiproxy_stub_map):
"""Constructor.
Args:
capabilities: list of strings
methods: list of strings
"""
if capabilities is None:
capabilities = []
if methods is None:
methods = []
self._package = package
self._capabilities = ['*'] + capabilities
self._methods = methods
self._stub_map = stub_map
def is_enabled(self):
"""Tests whether the capabilities is currently enabled.
Returns:
True if API calls that require these capabillities will succeed.
Raises:
UnknownCapabilityError, if a specified capability was not recognized.
"""
config = self._get_status()
return config.summary_status() in (IsEnabledResponse.ENABLED,
IsEnabledResponse.SCHEDULED_FUTURE,
IsEnabledResponse.SCHEDULED_NOW)
def will_remain_enabled_for(self, time=60):
"""Returns true if it will remain enabled for the specified amount of time.
Args:
time: Number of seconds in the future to look when checking for scheduled
downtime.
Returns:
True if there is no scheduled downtime for the specified capability
within the amount of time specified.
Raises:
UnknownCapabilityError, if a specified capability was not recognized.
"""
config = self._get_status()
status = config.summary_status()
if status == IsEnabledResponse.ENABLED:
return True
elif status == IsEnabledResponse.SCHEDULED_NOW:
return False
elif status == IsEnabledResponse.SCHEDULED_FUTURE:
if config.has_time_until_scheduled():
return config.time_until_scheduled() >= time
else:
return True
elif status == IsEnabledResponse.DISABLED:
return False
else:
return False
def admin_message(self):
"""Get any administrator notice messages for these capabilities.
Returns:
A string containing one or more admin messages, or an empty string.
Raises:
UnknownCapabilityError, if a specified capability was not recognized.
"""
message_list = []
for config in self._get_status().config_list():
message = config.admin_message()
if message and message not in message_list:
message_list.append(message)
return ' '.join(message_list)
def _get_status(self):
"""Get an IsEnabledResponse for the capabilities listed.
Returns:
IsEnabledResponse for the specified capabilities.
Raises:
UnknownCapabilityError: If an unknown capability was requested.
"""
req = IsEnabledRequest()
req.set_package(self._package)
for capability in self._capabilities:
req.add_capability(capability)
for method in self._methods:
req.add_call(method)
resp = capability_service_pb.IsEnabledResponse()
self._stub_map.MakeSyncCall('capability_service', 'IsEnabled', req, resp)
if resp.summary_status() == IsEnabledResponse.UNKNOWN:
raise UnknownCapabilityError()
return resp