#!/usr/bin/python

import sys
sys.path.append('/usr/lib/xen-default/lib/python/')
from xen.lowlevel import xs
from collections import defaultdict
import os
import re

xsc = xs.xs()

def live_vms():
    domids = set(xsc.ls('', '/local/domain'))

    vms = dict()

    for domid in domids:
        try:
            uuid, data = get_dom(int(domid))
        except (xs.Error, TypeError, AttributeError):
            continue # went down since we started
        vms[uuid] = data
    return vms

def get_dom(domid):
    data = dict(domid=domid)
    data['name'] = xsc.read('', '/local/domain/%d/name' % domid)
    # /vm contains a path like "/vm/UUID"; strip the "/vm/"
    data['uuid'] = xsc.read('', '/local/domain/%d/vm' % domid)[4:]
    if data['name'].startswith('d_'):
        data['munin_name'] = 'db domid %d' % domid
    else:
        data['munin_name'] = data['name']
    data['munin_var'] = 'uuid_'+data['uuid'].replace('-', '_')
    return data['munin_var'], data

def parse_net_dev():
    """Parse /proc/net/dev to determine down/up counters for each interface.

    N.B. Note that "down" and "up" are with respect to the host.
    """
    usage = {}
    for line in open('/proc/net/dev', 'r'):
        if ':' not in line:
            continue # skip header lines
        iface, fields = line.split(':')
        iface = iface.strip()
        fields = fields.split()
        usage[iface] = {'down': int(fields[0]),
                        'up': int(fields[8])}
    return usage

IFACE_NAME_RE = re.compile(r'^(vif|tap)(\d+)\.(\d+)$')

def get_net_usage():
    """Group /proc/net/dev counters by domain.

    N.B. Note that "down" and "up" are reversed - from the perspective of the guest.
    """
    by_dev = parse_net_dev()
    by_domain = defaultdict(lambda: {'down': 0, 'up': 0})
    for iface in by_dev:
        m = IFACE_NAME_RE.match(iface)
        if m:
            viftype, domid, ifcount = m.groups()
            domid = int(domid)
            by_domain[domid]['down'] += by_dev[iface]['up']
            by_domain[domid]['up'] += by_dev[iface]['down']
    return by_domain

if __name__ == '__main__':
    if len(sys.argv) > 1:
        cmd = sys.argv[1]
    else:
        cmd = None

    domains = live_vms()

    if cmd == 'config':
        print """
graph_title Xen domain network usage
graph_args --base 1000
graph_vlabel bits in (-) / out (+) per ${graph_period}
graph_info This graph shows how network is utilized by Xen domains.
graph_category network
graph_period second"""
        for d in sorted(domains):
            for direction in ('down', 'up'):
                key = "%s_%s" % (d, direction)
                print "%s.label %s" % (key, domains[d]['munin_name'])
                print "%s.max 10000000000" % key
                print "%s.min 0" % key
                print "%s.type DERIVE" % key
                print "%s.cdef %s,8,*" % (key, key)
                if direction == 'down':
                    print "%s.graph no" % key
                    print "%s.draw LINE1" % key
                else:
                    print "%s.negative %s_down" % (key, d)
                    print "%s.draw AREASTACK" % key
                print "%s.info uuid %s" % (key, domains[d]['uuid'])
        sys.exit(0)

    net_usage = get_net_usage()

    for d in sorted(domains):
        for direction in ('down', 'up'):
            print "%s_%s.value %d" % (d, direction, net_usage[domains[d]['domid']][direction])