scanner: add function to stop threads on SIGTERM

''' Measure the relays. '''

import signal

import sys

from ..lib.circuitbuilder import GapsCircuitBuilder as CB

from ..lib.resultdump import ResultDump

from ..lib.resultdump import ResultSuccess, ResultErrorCircuit

controller = None

def stop_threads(signal, frame):

    global rd, pool

    log.debug('Stopping sbws.')

    # Avoid new threads to start.

    settings.set_end_event()

    # Stop Pool threads

    pool.close()

    pool.join()

    # Stop ResultDump thread

    rd.thread.join()

    # Stop Tor thread

    controller.close()

    sys.exit(0)

signal.signal(signal.SIGTERM, stop_threads)

def timed_recv_from_server(session, dest, byte_range):

    ''' Request the **byte_range** from the URL at **dest**. If successful,

    return True and the time it took to download. Otherwise return False and an