#!/usr/bin/python2.5

import mailbox
import os
import time
import tempfile 

msg_text = ("""Subject: Ghost message

This message should be deleted.
""",
"""Subject: New message

This message should be the only one in the mailbox.
""")

mbox_name = tempfile.mkstemp(prefix="race-mbox")[1]

def printmbox(m): 
    if not mbox: print("<empty>")
    else: 
        for msg in mbox: print(msg)
    print

if os.fork(): 
    # first mbox user
    mbox = mailbox.mbox(mbox_name)
    mbox.lock()
    mbox.add(msg_text[0])
    mbox.clear() 
    print("=== mbox after first client finished:\n")
    printmbox(mbox) # now empty
    mbox.close()
    os.wait()
    mbox = mailbox.mbox(mbox_name)
    print("=== mbox after second client finished:\n")
    printmbox(mbox) # has now both messages. 
    os.remove(mbox_name)
else: 
    # second mbox user
    mbox = mailbox.mbox(mbox_name)
    time.sleep(1)
    mbox.lock()
    mbox.add(msg_text[1]) 
    mbox.close()