text: #!/usr/bin/env python3
  #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you 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 optparse
  import queue
  
  
  from proton import Message
  from proton.handlers import MessagingHandler
  from proton.reactor import ApplicationEvent, Container, EventInjector
  from db_common import Db
  
  
  class Send(MessagingHandler):
      def __init__(self, url, count):
          super(Send, self).__init__()
          self.url = url
          self.delay = 0
          self.sent = 0
          self.confirmed = 0
          self.load_count = 0
          self.records = queue.Queue(maxsize=50)
          self.target = count
          self.db = Db("src_db", EventInjector())
  
      def keep_sending(self):
          return self.target == 0 or self.sent < self.target
  
      def on_start(self, event):
          self.container = event.container
          self.container.selectable(self.db.injector)
          self.sender = self.container.create_sender(self.url)
  
      def on_records_loaded(self, event):
          if self.records.empty():
              if event.subject == self.load_count:
                  print("Exhausted available data, waiting to recheck...")
                  # check for new data after 5 seconds
                  self.container.schedule(5, self)
          else:
              self.send()
  
      def request_records(self):
          if not self.records.full():
              print("loading records...")
              self.load_count += 1
              self.db.load(self.records, event=ApplicationEvent(
                  "records_loaded", link=self.sender, subject=self.load_count))
  
      def on_sendable(self, event):
          self.send()
  
      def send(self):
          while self.sender.credit and not self.records.empty():
              if not self.keep_sending():
                  return
              record = self.records.get(False)
              id = record['id']
              self.sender.send(Message(id=id, durable=True, body=record['description']), tag=str(id))
              self.sent += 1
              print("sent message %s" % id)
          self.request_records()
  
      def on_settled(self, event):
          id = int(event.delivery.tag)
          self.db.delete(id)
          print("settled message %s" % id)
          self.confirmed += 1
          if self.confirmed == self.target:
              event.connection.close()
              self.db.close()
  
      def on_disconnected(self, event):
          self.db.reset()
          self.sent = self.confirmed
  
      def on_timer_task(self, event):
          print("Rechecking for data...")
          self.request_records()
  
  
  parser = optparse.OptionParser(usage="usage: %prog [options]",
                                 description="Send messages to the supplied address.")
  parser.add_option("-a", "--address", default="localhost:5672/examples",
                    help="address to which messages are sent (default %default)")
  parser.add_option("-m", "--messages", type="int", default=0,
                    help="number of messages to send; 0 sends indefinitely (default %default)")
  opts, args = parser.parse_args()
  
  try:
      Container(Send(opts.address, opts.messages)).run()
  except KeyboardInterrupt:
      pass
  