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# Copyright 2015, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import collections
import threading
import grpc
from grpc import _common
from grpc._cython import cygrpc
class AuthMetadataContext(
collections.namedtuple(
'AuthMetadataContext', ('service_url', 'method_name',)),
grpc.AuthMetadataContext):
pass
class AuthMetadataPluginCallback(grpc.AuthMetadataContext):
def __init__(self, callback):
self._callback = callback
def __call__(self, metadata, error):
self._callback(metadata, error)
class _WrappedCygrpcCallback(object):
def __init__(self, cygrpc_callback):
self.is_called = False
self.error = None
self.is_called_lock = threading.Lock()
self.cygrpc_callback = cygrpc_callback
def _invoke_failure(self, error):
# TODO(atash) translate different Exception superclasses into different
# status codes.
self.cygrpc_callback(
_common.EMPTY_METADATA, cygrpc.StatusCode.internal,
_common.encode(str(error)))
def _invoke_success(self, metadata):
try:
cygrpc_metadata = _common.cygrpc_metadata(metadata)
except Exception as error:
self._invoke_failure(error)
return
self.cygrpc_callback(cygrpc_metadata, cygrpc.StatusCode.ok, b'')
def __call__(self, metadata, error):
with self.is_called_lock:
if self.is_called:
raise RuntimeError('callback should only ever be invoked once')
if self.error:
self._invoke_failure(self.error)
return
self.is_called = True
if error is None:
self._invoke_success(metadata)
else:
self._invoke_failure(error)
def notify_failure(self, error):
with self.is_called_lock:
if not self.is_called:
self.error = error
class _WrappedPlugin(object):
def __init__(self, plugin):
self.plugin = plugin
def __call__(self, context, cygrpc_callback):
wrapped_cygrpc_callback = _WrappedCygrpcCallback(cygrpc_callback)
wrapped_context = AuthMetadataContext(
_common.decode(context.service_url), _common.decode(context.method_name))
try:
self.plugin(
wrapped_context, AuthMetadataPluginCallback(wrapped_cygrpc_callback))
except Exception as error:
wrapped_cygrpc_callback.notify_failure(error)
raise
def call_credentials_metadata_plugin(plugin, name):
"""
Args:
plugin: A callable accepting a grpc.AuthMetadataContext
object and a callback (itself accepting a list of metadata key/value
2-tuples and a None-able exception value). The callback must be eventually
called, but need not be called in plugin's invocation.
plugin's invocation must be non-blocking.
"""
return cygrpc.call_credentials_metadata_plugin(
cygrpc.CredentialsMetadataPlugin(_WrappedPlugin(plugin), _common.encode(name)))
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