scripts/render_block_graph.py

   1 #!/usr/bin/env python
   2 #
   3 # Render Qemu Block Graph
   4 #
   5 # Copyright (c) 2018 Virtuozzo International GmbH. All rights reserved.
   6 #
   7 # This program is free software; you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation; either version 2 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # This program is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 #
  20
  21 import os
  22 import sys
  23 import subprocess
  24 import json
  25 from graphviz import Digraph
  26 from qemu import MonitorResponseError
  27
  28
  29 def perm(arr):
  30     s = 'w' if 'write' in arr else '_'
  31     s += 'r' if 'consistent-read' in arr else '_'
  32     s += 'u' if 'write-unchanged' in arr else '_'
  33     s += 'g' if 'graph-mod' in arr else '_'
  34     s += 's' if 'resize' in arr else '_'
  35     return s
  36
  37
  38 def render_block_graph(qmp, filename, format='png'):
  39     '''
  40     Render graph in text (dot) representation into "@filename" and
  41     representation in @format into "@filename.@format"
  42     '''
  43
  44     bds_nodes = qmp.command('query-named-block-nodes')
  45     bds_nodes = {n['node-name']: n for n in bds_nodes}
  46
  47     job_nodes = qmp.command('query-block-jobs')
  48     job_nodes = {n['device']: n for n in job_nodes}
  49
  50     block_graph = qmp.command('x-debug-query-block-graph')
  51
  52     graph = Digraph(comment='Block Nodes Graph')
  53     graph.format = format
  54     graph.node('permission symbols:\l'
  55                '  w - Write\l'
  56                '  r - consistent-Read\l'
  57                '  u - write - Unchanged\l'
  58                '  g - Graph-mod\l'
  59                '  s - reSize\l'
  60                'edge label scheme:\l'
  61                '  <child type>\l'
  62                '  <perm>\l'
  63                '  <shared_perm>\l', shape='none')
  64
  65     for n in block_graph['nodes']:
  66         if n['type'] == 'block-driver':
  67             info = bds_nodes[n['name']]
  68             label = n['name'] + ' [' + info['drv'] + ']'
  69             if info['drv'] == 'file':
  70                 label += '\n' + os.path.basename(info['file'])
  71             shape = 'ellipse'
  72         elif n['type'] == 'block-job':
  73             info = job_nodes[n['name']]
  74             label = info['type'] + ' job (' + n['name'] + ')'
  75             shape = 'box'
  76         else:
  77             assert n['type'] == 'block-backend'
  78             label = n['name'] if n['name'] else 'unnamed blk'
  79             shape = 'box'
  80
  81         graph.node(str(n['id']), label, shape=shape)
  82
  83     for e in block_graph['edges']:
  84         label = '%s\l%s\l%s\l' % (e['name'], perm(e['perm']),
  85                                   perm(e['shared-perm']))
  86         graph.edge(str(e['parent']), str(e['child']), label=label)
  87
  88     graph.render(filename)
  89
  90
  91 class LibvirtGuest():
  92     def __init__(self, name):
  93         self.name = name
  94
  95     def command(self, cmd):
  96         # only supports qmp commands without parameters
  97         m = {'execute': cmd}
  98         ar = ['virsh', 'qemu-monitor-command', self.name, json.dumps(m)]
  99
 100         reply = json.loads(subprocess.check_output(ar))
 101
 102         if 'error' in reply:
 103             raise MonitorResponseError(reply)
 104
 105         return reply['return']
 106
 107
 108 if __name__ == '__main__':
 109     obj = sys.argv[1]
 110     out = sys.argv[2]
 111
 112     if os.path.exists(obj):
 113         # assume unix socket
 114         qmp = QEMUMonitorProtocol(obj)
 115         qmp.connect()
 116     else:
 117         # assume libvirt guest name
 118         qmp = LibvirtGuest(obj)
 119
 120     render_block_graph(qmp, out)