4.9.3. Detect Overwritten Messages in Ring Queues

import sys
from qpid.messaging import *
from qpid.datatypes import Serial

conn = Connection.establish("localhost:5672")
ssn = conn.session()

name="ring-sequence-queue"
key="my_sequence_key"
addr = "%s; {create:sender, delete:always, node: {x-declare: {arguments: {'qpid.queue_msg_sequence':'%s', 'qpid.policy_type':'ring', 'qpid.max_count':4}}}}"  % (name, key)
sender = ssn.sender(addr)

msg = Message()
sender.send(msg)

receiver = ssn.receiver(name)
msg = receiver.fetch(1)

try:
    seqNo = Serial(long(msg.properties[key]))
    if seqNo != 1:
        print "Unexpected sequence number. Should be 1. Received (%s)" % seqNo
    else:
       print "Received message with sequence number 1"
except:
    print "Unable to get key (%s) from message properties" % key

"""
Test that sequence number for ring queues shows gaps when queue messages are overwritten
"""

msg = Message()
sender.send(msg)
msg = receiver.fetch(1)
seqNo = Serial(long(msg.properties[key]))

print "Received second message with sequence number %s" % seqNo
# send 5 more messages to overflow the queue
for i in range(5):
    sender.send(msg)

msg = receiver.fetch(1)
seqNo = msg.properties[key]
if seqNo != 3:
    print "Unexpected sequence number. Should be 3. Received (%s) - Message overwritten in ring queue." % seqNo
receiver.close()
ssn.close()