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。