Traffic Monitor源码分析
从simple_switch_13.SimpleSwitch13控制器继承并开发
class SimpleMonitor13(simple_switch_13.SimpleSwitch13):
增添datapaths列表，存储交换机id
def __init__(self, *args, **kwargs):
super(SimpleMonitor13, self).__init__(*args, **kwargs)
self.datapaths = {}
引入hub.spawn()函数启动一个新线程，输入为一个新的方法_monitor。
创建一个EventOFPStateChange监听事件，监听MAIN_DISPATCHER,DEAD_DISPATCHER两种情况。
@set_ev_cls(ofp_event.EventOFPStateChange,
[MAIN_DISPATCHER, DEAD_DISPATCHER])
监听如果为MAIN_DISPATCHER,并且datapath.id不在datapath列表中，则证明是新加入的交换机
if ev.state == MAIN_DISPATCHER:
if datapath.id not in self.datapaths:
self.logger.debug('register datapath: %016x', datapath.id)
self.datapaths[datapath.id] = datapath
如果为DEAD_DISPATCHER，并且datapath.id在datapath列表中，则证明是掉线的交换机
elif ev.state == DEAD_DISPATCHER:
if datapath.id in self.datapaths:
self.logger.debug('unregister datapath: %016x', datapath.id)
del self.datapaths[datapath.id]
_monitor方法，循环不断向datapath列表中的交换机发送Flow状态请求，和Port状态请求
def _monitor(self):
while True:
for dp in self.datapaths.values():
self._request_stats(dp)
hub.sleep(10)
def _request_stats(self, datapath):
self.logger.debug('send stats request: %016x', datapath.id)
ofproto = datapath.ofproto
parser = datapath.ofproto_parser
req = parser.OFPFlowStatsRequest(datapath)
datapath.send_msg(req)
req = parser.OFPPortStatsRequest(datapath, 0, ofproto.OFPP_ANY)
datapath.send_msg(req)
刚刚发送了请求，现在监听其回复
@set_ev_cls(ofp_event.EventOFPFlowStatsReply, MAIN_DISPATCHER)
...
@set_ev_cls(ofp_event.EventOFPPortStatsReply, MAIN_DISPATCHER)
...
打印返回的信息
for stat in sorted([flow for flow in body if flow.priority == 1],
key=lambda flow: (flow.match['in_port'],
flow.match['eth_dst'])):
self.logger.info('%016x %8x %17s %8x %8d %8d',
ev.msg.datapath.id,
stat.match['in_port'], stat.match['eth_dst'],
stat.instructions[0].actions[0].port,
stat.packet_count, stat.byte_count)
...
for stat in sorted(body, key=attrgetter('port_no')):
self.logger.info('%016x %8x %8d %8d %8d %8d %8d %8d',
ev.msg.datapath.id, stat.port_no,
stat.rx_packets, stat.rx_bytes, stat.rx_errors,
stat.tx_packets, stat.tx_bytes, stat.tx_errors)
其中sorted ... lambda语法，指元组的排列顺序按照先in_port再eth_dst
至此，整个程序解析完毕。