api.py 文件源码

def __get__(self, instance, instance_type):
        """Construct the API client."""
        if instance is None:
            return self

        thread_local = None
        try:
            app = webapp2.get_app()
            # Python Google API clients aren't threadsafe as they use httplib2
            # which isn't threadsafe.
            thread_local = app.registry.get(self)
            if thread_local is None:
                thread_local = threading.local()
                app.registry[self] = thread_local
        except AssertionError:
            # When not in a request context, use class thread local.
            thread_local = ThreadsafeClientLocal._class_thread_local

        cached_client = getattr(thread_local, 'api', None)
        if cached_client is None:
            credentials = client.GoogleCredentials.get_application_default()
            if credentials.create_scoped_required():
                credentials = credentials.create_scoped(
                    'https://www.googleapis.com/auth/cloud-platform')
            cached_client = discovery.build(
                self.service,
                self.version,
                http=credentials.authorize(self.http),
                cache_discovery=self.cache_discovery)
            thread_local.api = cached_client
        return cached_client