import time
import threading
import signal
from datetime import datetime
last_in_bytes = None
last_out_bytes = None
def curr_traffic(inf):
    global last_in_bytes, last_out_bytes
    in_traffic, out_traffic = None, None
    with open('/proc/net/dev') as f:
        lines = f.readlines()
        for line in lines[2:]:
            line = line.strip()
            if line.startswith(inf + ':'):
                items = line.strip().split(':')[1].split()
                in_bytes, out_bytes = int(items[0]), int(items[8])
                if last_in_bytes:
                    in_traffic, out_traffic = in_bytes - last_in_bytes, out_bytes - last_out_bytes
                last_in_bytes, last_out_bytes = in_bytes, out_bytes
                return in_traffic, out_traffic
next_thread = None
exit_flag = False
def thread_job(f_handler, inf='eth0', interval=2):
    global next_thread, exit_flag
    time.sleep(interval)
    if not exit_flag:
        next_thread = threading.Thread(target=thread_job, args=(f_handler, inf, interval))
        next_thread.start()
    else:
        next_thread = None
    time_stamp = int(time.time())
    in_traffic, out_traffic = curr_traffic(inf)
    print in_traffic, out_traffic
    if in_traffic is not None and out_traffic is not None and not f_handler.closed:
        f_handler.write('%d, %d, %d\n' % (time_stamp, in_traffic, out_traffic))
def exit_func(signum, stack):
    global exit_flag
    exit_flag = True
    print("Exiting ...")
    cnt = 0
    while not next_thread and cnt < 3:
        time.sleep(1)
        cnt += 1
    if cnt >= 3:
        next_thread.exit()
def output_traffics(outfile, inf='eth0', interval=1):
    with open(outfile, 'w') as f:
        f.write('time, in_rate(B/s), out_rate(B/s)\n')
        thread_job(f, inf, interval)
        while not exit_flag:
            time.sleep(1)
if __name__ == '__main__':
    signal.signal(signal.SIGINT, exit_func)
    signal.signal(signal.SIGINT, exit_func)
    args = {
        'outfile': time.strftime("%Y%m%d%H%M%S", time.localtime(time.time())) + '.csv',
        'inf': 'eth0',
        'interval': 1
    }
    output_traffics(**args)