Run synchronous pull in Google Cloud Pub/Sub with the Python client API

Question

I can't find the returnImmediately flag in the Python client API. Is there any specific reason for that? Is there another way to pull queued message synchronously from a subscription in Python?

Answer 1

Google doesn't provide something like this. But you can easily workaround it by implementing your own Queue

from Queue import Queue

from google.cloud import pubsub

subscriber = pubsub.SubscriberClient()
topic = "projects/newproject-xxxxx/topics/tarunlalwani"
subscription_name = 'projects/newproject-xxxxx/subscriptions/sub1'

class SynchronousSubscription(object):

    def callback(self, message):
        print(message.data)
        message.ack()
        self.pending_messages.put(message)

    def __init__(self, subscription):
        self.subscription_future = subscriber.subscribe(subscription_name, self.callback)
        self.pending_messages = Queue()

    def consume_sync(self):
        return self.pending_messages.get()

sub = SynchronousSubscription(subscription_name)
data = sub.consume_sync()

And it does work great for me when I tested