no longer threading class, added example on how to execute as a separate process

packet_dumper.py

 import six
 import pika
-import threading
 import logging
-from datetime import timedelta, datetime
+from multiprocessing import Process
+from datetime import datetime
 import os
 from messages import *
 from pure_pcapy import Dumper, Pkthdr, DLT_IEEE802_15_4, DLT_RAW
 
 
-class AmqpDataPacketDumper(threading.Thread):
+class AmqpDataPacketDumper:
     """
     Sniffs data.serial and dumps into pcap file (assumes that frames are DLT_IEEE802_15_4)
     Sniffs data.tun and dumps into pcap file (assumes that frames are DLT_IEEE802_15_4)
@@ -19,32 +19,45 @@ class AmqpDataPacketDumper(threading.Thread):
         incl_len: the number of bytes of packet data actually captured and saved in the file. This value should never become larger than orig_len or the snaplen value of the global header.
         orig_len: the length of the packet as it appeared on the network when it was captured. If incl_len and orig_len differ, the actually saved packet size was limited by snaplen.
     """
-    COMPONENT_ID = 'capture_dumper'
+    COMPONENT_ID = 'capture_dumper_%s' % uuid.uuid1()  # uuid in case several dumpers listening to bus
+    DEFAULT_DUMP_DIR = './dumps'
 
-    def __init__(self, connection, topics):
-        threading.Thread.__init__(self)
-        # queues & default exchange declaration
-        self.messages_dumped = 0
+    def __init__(self, amqp_url, amqp_exchange, topics, dump_dir=None):
 
-        self.connection = connection
+        self.url = amqp_url
+        self.exchange = amqp_exchange
 
+        # setup connection
+        self.connection = pika.BlockingConnection(pika.URLParameters(self.url))
+
+        # queues & default exchange declaration
+        self.messages_dumped = 0
         self.channel = self.connection.channel()
 
         self.data_queue_name = 'data@%s' % self.COMPONENT_ID
-        self.channel.queue_declare(queue=self.data_queue_name, auto_delete=True)
+        self.channel.queue_declare(
+            queue=self.data_queue_name,
+            auto_delete=True,
+            arguments={'x-max-length': 100}
+        )
 
         for t in topics:
-            self.channel.queue_bind(exchange=AMQP_EXCHANGE,
+            self.channel.queue_bind(exchange=self.exchange,
                                     queue=self.data_queue_name,
                                     routing_key=t)
 
+        if dump_dir and os.path.isdir(dump_dir):
+            self.dump_dir = dump_dir
+        else:
+            self.dump_dir = self.DEFAULT_DUMP_DIR
+
         # Hello world message
         self.channel.basic_publish(
             body=json.dumps({'_type': '%s.info' % self.COMPONENT_ID,
                              'value': '%s is up!' % self.COMPONENT_ID, }
                             ),
             routing_key='control.%s.info' % self.COMPONENT_ID,
-            exchange=AMQP_EXCHANGE,
+            exchange=self.exchange,
             properties=pika.BasicProperties(
                 content_type='application/json',
             )
@@ -56,14 +69,14 @@ class AmqpDataPacketDumper(threading.Thread):
         datetime_string = time.strftime("%Y%m%d_%H%M")
         network_type = "DLT_IEEE802_15_4"
         self.pcap_15_4_dumper = Dumper(
-            filename="{0}_{1}.pcap".format(datetime_string, network_type),
+            filename=os.path.join(self.dump_dir, "{0}_{1}.pcap".format(datetime_string, network_type)),
             snaplen=200,
             network=DLT_IEEE802_15_4
         )
 
         network_type = "DLT_RAW"
         self.pcap_raw_ip_dumper = Dumper(
-            filename="{0}_{1}.pcap".format(datetime_string, network_type),
+            filename=os.path.join(self.dump_dir, "{0}_{1}.pcap".format(datetime_string, network_type)),
             snaplen=200,
             network=DLT_RAW
         )
@@ -151,12 +164,7 @@ class AmqpDataPacketDumper(threading.Thread):
         print('Bye byes!')
 
 
-if __name__ == '__main__':
-
-    MESSAGE_UI_SELECTOR = 1
-
-    logging.basicConfig(format='%(levelname)s:%(message)s', level=logging.INFO)
-
+def amqp_data_packet_dumper():
     try:
         AMQP_EXCHANGE = str(os.environ['AMQP_EXCHANGE'])
         print('Imported AMQP_EXCHANGE env var: %s' % AMQP_EXCHANGE)
@@ -185,8 +193,6 @@ if __name__ == '__main__':
         AMQP_URL = "amqp://{0}:{1}@{2}/{3}".format("guest", "guest", "localhost", "/")
 
     connection = pika.BlockingConnection(pika.URLParameters(AMQP_URL))
-    channel = connection.channel()
-    logging.info("AMQP connection established")
 
     # in case its not declared
     connection.channel().exchange_declare(exchange=AMQP_EXCHANGE,
@@ -201,7 +207,22 @@ if __name__ == '__main__':
                                      'data.tun.fromAgent.coap_client_agent',
                                      ]
     pcap_dumper = AmqpDataPacketDumper(
-        connection=connection,
-        topics=pcap_amqp_topic_subscriptions
+        amqp_url=AMQP_URL,
+        amqp_exchange=AMQP_EXCHANGE,
+        topics=pcap_amqp_topic_subscriptions,
+        dump_dir=None
     )
-    pcap_dumper.start()
+    # pcap_dumper.start()
+    pcap_dumper.run()
+
+
+if __name__ == '__main__':
+
+    logging.basicConfig(format='%(levelname)s:%(message)s', level=logging.DEBUG)
+
+    p = Process(target=amqp_data_packet_dumper, args=())
+    p.start()
+    for i in range(1, 1000):
+        time.sleep(1)
+        print(i)
+    p.join()