old_contents: # Copyright 2020 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.
  
  import os
  import sys
  import time
  
  from flask import Flask
  
  from google.cloud import datastore
  from google.cloud import pubsub_v1
  
  
  app = Flask(__name__)
  ds_client = datastore.Client()
  
  
  def error500():
      resp = {
          'message': 'Internal error occured.'
      }
      return resp, 500
  
  
  @app.route('/')
  def index():
      return 'Event Publisher service. '
  
  
  @app.route('/api/v1/event/publish', methods=['GET'])
  def publish_event():
      futures = {}
      def get_callback(future, result):
          def callback(future):
              event_id = result['event_id']
              try:
                  future.result()
                  result['published'] = True
                  ds_client.put(result)
              except:
                  print('Failed to publish an envent {}: {}'.format(event_id, future.exception()),
                          file=sys.stderr)
              finally:
                  futures.pop(event_id)
          return callback
  
      query = ds_client.query(kind='Event')
      query.add_filter('published', '=', False)
      query.order = ['timestamp']
      for result in query.fetch():
          publisher = pubsub_v1.PublisherClient()
          topic_name = 'projects/{}/topics/{}'.format(
              os.getenv('PROJECT_ID'), result['topic'])
          event_id = result['event_id']
          event_type = result['type']
          body = result['body'].encode("utf-8")
  
          future = publisher.publish(topic_name, body,
                      event_id=event_id, event_type=event_type)
          futures[event_id] = future
          future.add_done_callback(get_callback(future, result))
  
      while futures:
          time.sleep(5)
  
      return 'Finished.', 200
  
  
  if __name__ == "__main__":
      app.run(debug=True, host='0.0.0.0', port=int(os.environ.get('PORT', 8080)))
  
new_contents: # Copyright 2020 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.
  
  import os
  import sys
  import time
  
  from flask import Flask
  
  from google.cloud import datastore
  from google.cloud import pubsub_v1
  
  
  app = Flask(__name__)
  ds_client = datastore.Client()
  
  
  def error500():
      resp = {
          'message': 'Internal error occured.'
      }
      return resp, 500
  
  
  @app.route('/')
  def index():
      return 'Event Publisher service. '
  
  
  @app.route('/api/v1/event/publish', methods=['GET'])
  def publish_event():
      futures = {}
      def get_callback(future, result):
          def callback(future):
              event_id = result['event_id']
              try:
                  future.result()
                  result['published'] = True
                  ds_client.put(result)
              except:
                  print('Failed to publish an event {}: {}'.format(event_id, future.exception()),
                          file=sys.stderr)
              finally:
                  futures.pop(event_id)
          return callback
  
      query = ds_client.query(kind='Event')
      query.add_filter('published', '=', False)
      query.order = ['timestamp']
      for result in query.fetch():
          publisher = pubsub_v1.PublisherClient()
          topic_name = 'projects/{}/topics/{}'.format(
              os.getenv('PROJECT_ID'), result['topic'])
          event_id = result['event_id']
          event_type = result['type']
          body = result['body'].encode("utf-8")
  
          future = publisher.publish(topic_name, body,
                      event_id=event_id, event_type=event_type)
          futures[event_id] = future
          future.add_done_callback(get_callback(future, result))
  
      while futures:
          time.sleep(5)
  
      return 'Finished.', 200
  
  
  if __name__ == "__main__":
      app.run(debug=True, host='0.0.0.0', port=int(os.environ.get('PORT', 8080)))
  
subject: Update main.py