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subscriber.py
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subscriber.py
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#!/usr/bin/env python
# Copyright 2016 Google Inc. All Rights Reserved.
#
# 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.
"""This application demonstrates how to perform basic operations on
subscriptions with the Cloud Pub/Sub API.
For more information, see the README.md under /pubsub and the documentation
at https://cloud.google.com/pubsub/docs.
"""
import argparse
def list_subscriptions_in_topic(project_id, topic_name):
"""Lists all subscriptions for a given topic."""
# [START pubsub_list_topic_subscriptions]
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO topic_name = "Your Pub/Sub topic name"
publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path(project_id, topic_name)
for subscription in publisher.list_topic_subscriptions(topic_path):
print(subscription)
# [END pubsub_list_topic_subscriptions]
def list_subscriptions_in_project(project_id):
"""Lists all subscriptions in the current project."""
# [START pubsub_list_subscriptions]
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
subscriber = pubsub_v1.SubscriberClient()
project_path = subscriber.project_path(project_id)
for subscription in subscriber.list_subscriptions(project_path):
print(subscription.name)
# [END pubsub_list_subscriptions]
def create_subscription(project_id, topic_name, subscription_name):
"""Create a new pull subscription on the given topic."""
# [START pubsub_create_pull_subscription]
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO topic_name = "Your Pub/Sub topic name"
# TODO subscription_name = "Your Pub/Sub subscription name"
subscriber = pubsub_v1.SubscriberClient()
topic_path = subscriber.topic_path(project_id, topic_name)
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
subscription = subscriber.create_subscription(
subscription_path, topic_path)
print('Subscription created: {}'.format(subscription))
# [END pubsub_create_pull_subscription]
def create_push_subscription(project_id,
topic_name,
subscription_name,
endpoint):
"""Create a new push subscription on the given topic."""
# [START pubsub_create_push_subscription]
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO topic_name = "Your Pub/Sub topic name"
# TODO subscription_name = "Your Pub/Sub subscription name"
# TODO endpoint = "https://my-test-project.appspot.com/push"
subscriber = pubsub_v1.SubscriberClient()
topic_path = subscriber.topic_path(project_id, topic_name)
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
push_config = pubsub_v1.types.PushConfig(
push_endpoint=endpoint)
subscription = subscriber.create_subscription(
subscription_path, topic_path, push_config)
print('Push subscription created: {}'.format(subscription))
print('Endpoint for subscription is: {}'.format(endpoint))
# [END pubsub_create_push_subscription]
def delete_subscription(project_id, subscription_name):
"""Deletes an existing Pub/Sub topic."""
# [START pubsub_delete_subscription]
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO subscription_name = "Your Pub/Sub subscription name"
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
subscriber.delete_subscription(subscription_path)
print('Subscription deleted: {}'.format(subscription_path))
# [END pubsub_delete_subscription]
def update_subscription(project_id, subscription_name, endpoint):
"""
Updates an existing Pub/Sub subscription's push endpoint URL.
Note that certain properties of a subscription, such as
its topic, are not modifiable.
"""
# [START pubsub_update_push_configuration]
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO topic_name = "Your Pub/Sub topic name"
# TODO subscription_name = "Your Pub/Sub subscription name"
# TODO endpoint = "https://my-test-project.appspot.com/push"
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
push_config = pubsub_v1.types.PushConfig(
push_endpoint=endpoint)
subscription = pubsub_v1.types.Subscription(
name=subscription_path,
push_config=push_config)
update_mask = {
'paths': {
'push_config',
}
}
subscriber.update_subscription(subscription, update_mask)
result = subscriber.get_subscription(subscription_path)
print('Subscription updated: {}'.format(subscription_path))
print('New endpoint for subscription is: {}'.format(
result.push_config))
# [END pubsub_update_push_configuration]
def receive_messages(project_id, subscription_name):
"""Receives messages from a pull subscription."""
# [START pubsub_subscriber_async_pull]
# [START pubsub_quickstart_subscriber]
import time
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO subscription_name = "Your Pub/Sub subscription name"
subscriber = pubsub_v1.SubscriberClient()
# The `subscription_path` method creates a fully qualified identifier
# in the form `projects/{project_id}/subscriptions/{subscription_name}`
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
def callback(message):
print('Received message: {}'.format(message))
message.ack()
subscriber.subscribe(subscription_path, callback=callback)
# The subscriber is non-blocking. We must keep the main thread from
# exiting to allow it to process messages asynchronously in the background.
print('Listening for messages on {}'.format(subscription_path))
while True:
time.sleep(60)
# [END pubsub_subscriber_async_pull]
# [END pubsub_quickstart_subscriber]
def receive_messages_with_custom_attributes(project_id, subscription_name):
"""Receives messages from a pull subscription."""
# [START pubsub_subscriber_sync_pull_custom_attributes]
import time
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO subscription_name = "Your Pub/Sub subscription name"
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
def callback(message):
print('Received message: {}'.format(message.data))
if message.attributes:
print('Attributes:')
for key in message.attributes:
value = message.attributes.get(key)
print('{}: {}'.format(key, value))
message.ack()
subscriber.subscribe(subscription_path, callback=callback)
# The subscriber is non-blocking, so we must keep the main thread from
# exiting to allow it to process messages in the background.
print('Listening for messages on {}'.format(subscription_path))
while True:
time.sleep(60)
# [END pubsub_subscriber_sync_pull_custom_attributes]
def receive_messages_with_flow_control(project_id, subscription_name):
"""Receives messages from a pull subscription with flow control."""
# [START pubsub_subscriber_flow_settings]
import time
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO subscription_name = "Your Pub/Sub subscription name"
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
def callback(message):
print('Received message: {}'.format(message.data))
message.ack()
# Limit the subscriber to only have ten outstanding messages at a time.
flow_control = pubsub_v1.types.FlowControl(max_messages=10)
subscriber.subscribe(
subscription_path, callback=callback, flow_control=flow_control)
# The subscriber is non-blocking, so we must keep the main thread from
# exiting to allow it to process messages in the background.
print('Listening for messages on {}'.format(subscription_path))
while True:
time.sleep(60)
# [END pubsub_subscriber_flow_settings]
def synchronous_pull(project_id, subscription_name):
"""Pulling messages synchronously."""
# [START pubsub_subscriber_sync_pull]
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO subscription_name = "Your Pub/Sub subscription name"
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
NUM_MESSAGES = 3
# The subscriber pulls a specific number of messages.
response = subscriber.pull(subscription_path, max_messages=NUM_MESSAGES)
ack_ids = []
for received_message in response.received_messages:
print("Received: {}".format(received_message.message.data))
ack_ids.append(received_message.ack_id)
# Acknowledges the received messages so they will not be sent again.
subscriber.acknowledge(subscription_path, ack_ids)
print("Received and acknowledged {} messages. Done.".format(NUM_MESSAGES))
# [END pubsub_subscriber_sync_pull]
def synchronous_pull_with_lease_management(project_id, subscription_name):
"""Pulling messages synchronously with lease management"""
# [START pubsub_subscriber_sync_pull_with_lease]
import logging
import multiprocessing
import random
import time
from google.cloud import pubsub_v1
# TODO project_id = "Your Google Cloud Project ID"
# TODO subscription_name = "Your Pub/Sub subscription name"
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
NUM_MESSAGES = 2
ACK_DEADLINE = 30
SLEEP_TIME = 10
# The subscriber pulls a specific number of messages.
response = subscriber.pull(subscription_path, max_messages=NUM_MESSAGES)
multiprocessing.log_to_stderr()
logger = multiprocessing.get_logger()
logger.setLevel(logging.INFO)
def worker(msg):
"""Simulates a long-running process."""
RUN_TIME = random.randint(1, 60)
logger.info('{}: Running {} for {}s'.format(
time.strftime("%X", time.gmtime()), msg.message.data, RUN_TIME))
time.sleep(RUN_TIME)
# `processes` stores process as key and ack id and message as values.
processes = dict()
for message in response.received_messages:
process = multiprocessing.Process(target=worker, args=(message,))
processes[process] = (message.ack_id, message.message.data)
process.start()
while processes:
for process in list(processes):
ack_id, msg_data = processes[process]
# If the process is still running, reset the ack deadline as
# specified by ACK_DEADLINE once every while as specified
# by SLEEP_TIME.
if process.is_alive():
# `ack_deadline_seconds` must be between 10 to 600.
subscriber.modify_ack_deadline(
subscription_path,
[ack_id],
ack_deadline_seconds=ACK_DEADLINE)
logger.info('{}: Reset ack deadline for {} for {}s'.format(
time.strftime("%X", time.gmtime()),
msg_data, ACK_DEADLINE))
# If the processs is finished, acknowledges using `ack_id`.
else:
subscriber.acknowledge(subscription_path, [ack_id])
logger.info("{}: Acknowledged {}".format(
time.strftime("%X", time.gmtime()), msg_data))
processes.pop(process)
# If there are still processes running, sleeps the thread.
if processes:
time.sleep(SLEEP_TIME)
print("Received and acknowledged {} messages. Done.".format(NUM_MESSAGES))
# [END pubsub_subscriber_sync_pull_with_lease]
def listen_for_errors(project_id, subscription_name):
"""Receives messages and catches errors from a pull subscription."""
# [START pubsub_subscriber_error_listener]
from google.cloud import pubsub_v1
# TODO project = "Your Google Cloud Project ID"
# TODO subscription_name = "Your Pubsub subscription name"
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project_id, subscription_name)
def callback(message):
print('Received message: {}'.format(message))
message.ack()
future = subscriber.subscribe(subscription_path, callback=callback)
# Blocks the thread while messages are coming in through the stream. Any
# exceptions that crop up on the thread will be set on the future.
try:
# When timeout is unspecified, the result method waits indefinitely.
future.result(timeout=30)
except Exception as e:
print(
'Listening for messages on {} threw an Exception: {}.'.format(
subscription_name, e))
# [END pubsub_subscriber_error_listener]
if __name__ == '__main__':
parser = argparse.ArgumentParser(
description=__doc__,
formatter_class=argparse.RawDescriptionHelpFormatter
)
parser.add_argument('project_id', help='Your Google Cloud project ID')
subparsers = parser.add_subparsers(dest='command')
list_in_topic_parser = subparsers.add_parser(
'list_in_topic', help=list_subscriptions_in_topic.__doc__)
list_in_topic_parser.add_argument('topic_name')
list_in_project_parser = subparsers.add_parser(
'list_in_project', help=list_subscriptions_in_project.__doc__)
create_parser = subparsers.add_parser(
'create', help=create_subscription.__doc__)
create_parser.add_argument('topic_name')
create_parser.add_argument('subscription_name')
create_push_parser = subparsers.add_parser(
'create-push', help=create_push_subscription.__doc__)
create_push_parser.add_argument('topic_name')
create_push_parser.add_argument('subscription_name')
create_push_parser.add_argument('endpoint')
delete_parser = subparsers.add_parser(
'delete', help=delete_subscription.__doc__)
delete_parser.add_argument('subscription_name')
update_parser = subparsers.add_parser(
'update', help=update_subscription.__doc__)
update_parser.add_argument('subscription_name')
update_parser.add_argument('endpoint')
receive_parser = subparsers.add_parser(
'receive', help=receive_messages.__doc__)
receive_parser.add_argument('subscription_name')
receive_with_custom_attributes_parser = subparsers.add_parser(
'receive-custom-attributes',
help=receive_messages_with_custom_attributes.__doc__)
receive_with_custom_attributes_parser.add_argument('subscription_name')
receive_with_flow_control_parser = subparsers.add_parser(
'receive-flow-control',
help=receive_messages_with_flow_control.__doc__)
receive_with_flow_control_parser.add_argument('subscription_name')
synchronous_pull_parser = subparsers.add_parser(
'receive-synchronously',
help=synchronous_pull.__doc__)
synchronous_pull_parser.add_argument('subscription_name')
synchronous_pull_with_lease_management_parser = subparsers.add_parser(
'receive-synchronously-with-lease',
help=synchronous_pull_with_lease_management.__doc__)
synchronous_pull_with_lease_management_parser.add_argument(
'subscription_name')
listen_for_errors_parser = subparsers.add_parser(
'listen_for_errors', help=listen_for_errors.__doc__)
listen_for_errors_parser.add_argument('subscription_name')
args = parser.parse_args()
if args.command == 'list_in_topic':
list_subscriptions_in_topic(args.project_id, args.topic_name)
elif args.command == 'list_in_project':
list_subscriptions_in_project(args.project_id)
elif args.command == 'create':
create_subscription(
args.project_id, args.topic_name, args.subscription_name)
elif args.command == 'create-push':
create_push_subscription(
args.project_id,
args.topic_name,
args.subscription_name,
args.endpoint)
elif args.command == 'delete':
delete_subscription(
args.project_id, args.subscription_name)
elif args.command == 'update':
update_subscription(
args.project_id, args.subscription_name, args.endpoint)
elif args.command == 'receive':
receive_messages(args.project_id, args.subscription_name)
elif args.command == 'receive-custom-attributes':
receive_messages_with_custom_attributes(
args.project_id, args.subscription_name)
elif args.command == 'receive-flow-control':
receive_messages_with_flow_control(
args.project_id, args.subscription_name)
elif args.command == 'receive-synchronously':
synchronous_pull(
args.project_id, args.subscription_name)
elif args.command == 'receive-synchronously-with-lease':
synchronous_pull_with_lease_management(
args.project_id, args.subscription_name)
elif args.command == 'listen_for_errors':
listen_for_errors(args.project_id, args.subscription_name)