~launchpad-pqm/launchpad/devel

#!/usr/bin/env python

__metaclass__ = type

import sys

import subprocess

from script_commands import (

    helps,

    run_subcommand,

    UserError,

    )

def tc(command):

    """Run a tc command under sudo.

    :param tc: The remainder of the command (leaving out tc).

    """

    subprocess.call('sudo tc ' + command, shell=True)

@helps(delay='Length of delay in miliseconds (each way).',

       port='Port to induce delay on.')

def start(delay=500, port=443):

    """Add artificial latency to the lo interface on the specified port."""

    tc('qdisc add dev lo root handle 1: prio')

    tc('qdisc add dev lo parent 1:3 handle 30: netem delay %dms' % delay)

    tc('filter add dev lo protocol ip parent 1:0 prio 3 u32 match ip'

       ' dport %d 0xffff flowid 1:3' % port)

    tc('filter add dev lo protocol ip parent 1:0 prio 3 u32 match ip'

       ' sport %d 0xffff flowid 1:3' % port)

def stop():

    """Remove latency from the lo."""

    tc('qdisc del dev lo root')

subcommands = {

    'start': start,

    'stop': stop,

    }

if __name__ == "__main__":

    try:

        run_subcommand(subcommands, sys.argv[1:])

    except UserError as e:

        sys.stderr.write(str(e)+'\n')