of-diff

#!/usr/bin/env python

import sys
import subprocess
import re
import time
import json

br = sys.argv[1]

keys = ('table', 'priority', 'actions', 'NXST_FLOW', 'cookie', 'ip', 'zone', 'ipv6', 'reg5')
values = ('n_packets', 'n_bytes')
skips = ('idle_age', 'duration')

stats = {}

while True:
    p = subprocess.Popen("ovs-ofctl dump-flows %s" % (br),
                         shell=True,
                         stdout=subprocess.PIPE)
    for l in p.stdout:
        key = {}
        value = {}
        for e in l.strip().split(', '):
            try:
                k, v = e.split('=', 1)
            except:
                k = e
                v = None
            if k in keys:
                key[k] = v
            elif k in values:
                value[k] = int(v)
            elif k in skips:
                pass
            else:
                pass

        jkey = json.dumps(key)
        prev_stats = stats.get(jkey, {})
        diff = False
        for k in value:
            if value[k] != prev_stats.get(k, 0):
                diff = True
                break
        if diff:
            delta = {}
            for k in value:
                delta[k] = value[k] - prev_stats.get(k, 0)
            print key, delta
        stats[jkey] = value

    print

    time.sleep(1)