# init ovs first by agent_config：

# setup plugin_rpc, state_rpc, msgq consumer, periodically state report

# setup br-int, br-tun, bridge_mapping

# start sg_agent
agent = OVSNeutronAgent(**agent_config)
# start to process rpc events

# process port up/down and related flow update/local vlan bounding

# process security group updates
agent.daemon_loop()

class OVSNeutronAgent(n_rpc.RpcCallback,
                      sg_rpc.SecurityGroupAgentRpcCallbackMixin,
                      l2population_rpc.L2populationRpcCallBackMixin):
    '''Implements OVS-based tunneling, VLANs and flat networks.

    Two local bridges are created: an integration bridge (defaults to
    'br-int') and a tunneling bridge (defaults to 'br-tun'). An
    additional bridge is created for each physical network interface
    used for VLANs and/or flat networks.

    All VM VIFs are plugged into the integration bridge. VM VIFs on a
    given virtual network share a common "local" VLAN (i.e. not
    propagated externally). The VLAN id of this local VLAN is mapped
    to the physical networking details realizing that virtual network.

    For virtual networks realized as GRE tunnels, a Logical Switch
    (LS) identifier is used to differentiate tenant traffic on
    inter-HV tunnels. A mesh of tunnels is created to other
    Hypervisors in the cloud. These tunnels originate and terminate on
    the tunneling bridge of each hypervisor. Port patching is done to
    connect local VLANs on the integration bridge to inter-hypervisor
    tunnels on the tunnel bridge.

    For each virtual network realized as a VLAN or flat network, a
    veth or a pair of patch ports is used to connect the local VLAN on
    the integration bridge with the physical network bridge, with flow
    rules adding, modifying, or stripping VLAN tags as necessary.
    '''

    # history
    #   1.0 Initial version
    #   1.1 Support Security Group RPC
    RPC_API_VERSION = '1.1'

    def __init__(self, integ_br, tun_br, local_ip,
                 bridge_mappings, root_helper,
                 polling_interval, tunnel_types=None,
                 veth_mtu=None, l2_population=False,
                 minimize_polling=False,
                 ovsdb_monitor_respawn_interval=(
                     constants.DEFAULT_OVSDBMON_RESPAWN),
                 arp_responder=False,
                 use_veth_interconnection=False):
        '''Constructor.

        :param integ_br: name of the integration bridge.
        :param tun_br: name of the tunnel bridge.
        :param local_ip: local IP address of this hypervisor.
        :param bridge_mappings: mappings from physical network name to bridge.
        :param root_helper: utility to use when running shell cmds.
        :param polling_interval: interval (secs) to poll DB.
        :param tunnel_types: A list of tunnel types to enable support for in
               the agent. If set, will automatically set enable_tunneling to
               True.
        :param veth_mtu: MTU size for veth interfaces.
        :param l2_population: Optional, whether L2 population is turned on
        :param minimize_polling: Optional, whether to minimize polling by
               monitoring ovsdb for interface changes.
        :param ovsdb_monitor_respawn_interval: Optional, when using polling
               minimization, the number of seconds to wait before respawning
               the ovsdb monitor.
        :param arp_responder: Optional, enable local ARP responder if it is
               supported.
        :param use_veth_interconnection: use veths instead of patch ports to
               interconnect the integration bridge to physical bridges.
        '''
        super(OVSNeutronAgent, self).__init__()
        self.use_veth_interconnection = use_veth_interconnection
        self.veth_mtu = veth_mtu
        self.root_helper = root_helper
        self.available_local_vlans = set(moves.xrange(q_const.MIN_VLAN_TAG, # 1-1094
                                                      q_const.MAX_VLAN_TAG))
        self.tunnel_types = tunnel_types or []
        self.l2_pop = l2_population
        # TODO(ethuleau): Initially, local ARP responder is be dependent to the
        #                 ML2 l2 population mechanism driver.
        self.arp_responder_enabled = (arp_responder and
                                      self._check_arp_responder_support() and
                                      self.l2_pop)
        self.agent_state = {
            'binary': 'neutron-openvswitch-agent',
            'host': cfg.CONF.host,
            'topic': q_const.L2_AGENT_TOPIC,
            'configurations': {'bridge_mappings': bridge_mappings,
                               'tunnel_types': self.tunnel_types,
                               'tunneling_ip': local_ip,
                               'l2_population': self.l2_pop,
                               'arp_responder_enabled':
                               self.arp_responder_enabled},
            'agent_type': q_const.AGENT_TYPE_OVS,
            'start_flag': True}

        # Keep track of int_br's device count for use by _report_state()
        self.int_br_device_count = 0

        self.int_br = ovs_lib.OVSBridge(integ_br, self.root_helper)
        # Create integration bridge and patch ports, 
        # remove all existing flows, and then witch all traffic using L2 learning
        # add a canary flow to int_br to track OVS restarts
        self.setup_integration_br()

        # Stores port update notifications for processing in main rpc loop
        self.updated_ports = set()

        # state_rpc: periodically report state by topic q-plugin
        # plugin_rpc:communicate with plugin by topic q-agent-notifier
        # consumer topic id includes:
        #       q-agent-notifier-port_update
        #       q-agent-notifier-network_delete
        #       q-agent-notifier-tunnel_update
        #       q-agent-notifier-security_group_update
        #       q-agent-notifier-l2population_update （需要启动l2populcation）
        self.setup_rpc()

        # bridge_mappings = default:br-eth1
        self.bridge_mappings = bridge_mappings
        # Creates physical network bridges and links them to integration bridge using veths.
        self.setup_physical_bridges(self.bridge_mappings)

        self.local_vlan_map = {}
        self.tun_br_ofports = {p_const.TYPE_GRE: {},
                               p_const.TYPE_VXLAN: {}}

        self.polling_interval = polling_interval
        self.minimize_polling = minimize_polling
        self.ovsdb_monitor_respawn_interval = ovsdb_monitor_respawn_interval

        if tunnel_types:
            self.enable_tunneling = True
        else:
            self.enable_tunneling = False
        self.local_ip = local_ip
        self.tunnel_count = 0
        self.vxlan_udp_port = cfg.CONF.AGENT.vxlan_udp_port
        self.dont_fragment = cfg.CONF.AGENT.dont_fragment
        self.tun_br = None

        # Creates tunnel bridge, and links it to the integration bridge
        # using a patch port.
        # create default flow tables
        if self.enable_tunneling:
            self.setup_tunnel_br(tun_br)

        # Collect additional bridges to monitor
        # Setup ancillary bridges - for example br-ex
        self.ancillary_brs = self.setup_ancillary_bridges(integ_br, tun_br)

        # Security group agent support
        # firewall_driver = neutron.agent.linux.iptables_firewall.OVSHybridIptablesFirewallDriver
        self.sg_agent = OVSSecurityGroupAgent(self.context,
                                              self.plugin_rpc,
                                              root_helper)
        # Initialize iteration counter
        self.iter_num = 0
        self.run_daemon_loop = True

    def daemon_loop(self):
        with polling.get_polling_manager(
            self.minimize_polling,
            self.root_helper,
            self.ovsdb_monitor_respawn_interval) as pm:

            self.rpc_loop(polling_manager=pm)

   def rpc_loop(self, polling_manager=None):
        # sync tunnel and check ovs restart
        if not polling_manager:
            polling_manager = polling.AlwaysPoll()

        sync = True
        ports = set()
        updated_ports_copy = set()
        ancillary_ports = set()
        tunnel_sync = True
        ovs_restarted = False
        while self.run_daemon_loop:
            start = time.time()
            port_stats = {'regular': {'added': 0,
                                      'updated': 0,
                                      'removed': 0},
                          'ancillary': {'added': 0,
                                        'removed': 0}}
            LOG.debug(_("Agent rpc_loop - iteration:%d started"),
                      self.iter_num)
            if sync:
                LOG.info(_("Agent out of sync with plugin!"))
                ports.clear()
                ancillary_ports.clear()
                sync = False
                polling_manager.force_polling()
            # check ovs restart by checking exist for the canary flow
            ovs_restarted = self.check_ovs_restart()
            if ovs_restarted: 
                # reset br-int, br-tun, and other physical bridges
                self.setup_integration_br()
                self.setup_physical_bridges(self.bridge_mappings)
                if self.enable_tunneling:
                    self.setup_tunnel_br()
                    tunnel_sync = True

            # Notify the plugin of tunnel IP
            if self.enable_tunneling and tunnel_sync:
                LOG.info(_("Agent tunnel out of sync with plugin!"))
                try:
                    tunnel_sync = self.tunnel_sync()
                except Exception:
                    LOG.exception(_("Error while synchronizing tunnels"))
                    tunnel_sync = True

            # check if ports/security_groups updates and perform update
            if self._agent_has_updates(polling_manager) or ovs_restarted:
                try:
                    LOG.debug(_("Agent rpc_loop - iteration:%(iter_num)d - "
                                "starting polling. Elapsed:%(elapsed).3f"),
                              {'iter_num': self.iter_num,
                               'elapsed': time.time() - start})
                    # Save updated ports dict to perform rollback in
                    # case resync would be needed, and then clear
                    # self.updated_ports. As the greenthread should not yield
                    # between these two statements, this will be thread-safe
                    updated_ports_copy = self.updated_ports
                    self.updated_ports = set()
                    reg_ports = (set() if ovs_restarted else ports)
                    # {
                    #   'current': ['ovs-vsctl', --format=json', '--', '--columns=name,external_ids,ofport','list', 'Interface'] and then filted in get_vif_port_set()
                    #   'updated': check_changed_vlans() returns a set of port ids of the ports concerned by a vlan tag loss, and then updated_ports &= cur_ports
                    #   'added'  : cur_ports - registered_ports
                    #   'removed': registered_ports - cur_ports
                    #  }
                    port_info = self.scan_ports(reg_ports, updated_ports_copy)
                    LOG.debug(_("Agent rpc_loop - iteration:%(iter_num)d - "
                                "port information retrieved. "
                                "Elapsed:%(elapsed).3f"),
                              {'iter_num': self.iter_num,
                               'elapsed': time.time() - start})
                    # Secure and wire/unwire VIFs and update their status
                    # on Neutron server
                    if (self._port_info_has_changes(port_info) or
                        self.sg_agent.firewall_refresh_needed() or
                        ovs_restarted):
                        LOG.debug(_("Starting to process devices in:%s"),
                                  port_info)
                        # If treat devices fails - must resync with plugin
                        sync = self.process_network_ports(port_info,
                                                          ovs_restarted)
                        LOG.debug(_("Agent rpc_loop - iteration:%(iter_num)d -"
                                    "ports processed. Elapsed:%(elapsed).3f"),
                                  {'iter_num': self.iter_num,
                                   'elapsed': time.time() - start})
                        port_stats['regular']['added'] = (
                            len(port_info.get('added', [])))
                        port_stats['regular']['updated'] = (
                            len(port_info.get('updated', [])))
                        port_stats['regular']['removed'] = (
                            len(port_info.get('removed', [])))
                    ports = port_info['current']
                    # Treat ancillary devices if they exist
                    if self.ancillary_brs:
                        port_info = self.update_ancillary_ports(
                            ancillary_ports)
                        LOG.debug(_("Agent rpc_loop - iteration:%(iter_num)d -"
                                    "ancillary port info retrieved. "
                                    "Elapsed:%(elapsed).3f"),
                                  {'iter_num': self.iter_num,
                                   'elapsed': time.time() - start})

                        if port_info:
                            rc = self.process_ancillary_network_ports(
                                port_info)
                            LOG.debug(_("Agent rpc_loop - iteration:"
                                        "%(iter_num)d - ancillary ports "
                                        "processed. Elapsed:%(elapsed).3f"),
                                      {'iter_num': self.iter_num,
                                       'elapsed': time.time() - start})
                            ancillary_ports = port_info['current']
                            port_stats['ancillary']['added'] = (
                                len(port_info.get('added', [])))
                            port_stats['ancillary']['removed'] = (
                                len(port_info.get('removed', [])))
                            sync = sync | rc

                    polling_manager.polling_completed()
                except Exception:
                    LOG.exception(_("Error while processing VIF ports"))
                    # Put the ports back in self.updated_port
                    self.updated_ports |= updated_ports_copy
                    sync = True

            # sleep till end of polling interval
            elapsed = (time.time() - start)
            LOG.debug(_("Agent rpc_loop - iteration:%(iter_num)d "
                        "completed. Processed ports statistics: "
                        "%(port_stats)s. Elapsed:%(elapsed).3f"),
                      {'iter_num': self.iter_num,
                       'port_stats': port_stats,
                       'elapsed': elapsed})
            if (elapsed < self.polling_interval):
                time.sleep(self.polling_interval - elapsed)
            else:
                LOG.debug(_("Loop iteration exceeded interval "
                            "(%(polling_interval)s vs. %(elapsed)s)!"),
                          {'polling_interval': self.polling_interval,
                           'elapsed': elapsed})
            self.iter_num = self.iter_num + 1

    def tunnel_sync(self):
        resync = False
        try:
            for tunnel_type in self.tunnel_types:  # tunnel_types = vxlan, gre
                # query tunnel details from plugin_rpc by local_ip and tunnel_type
                details = self.plugin_rpc.tunnel_sync(self.context,
                                                      self.local_ip,
                                                      tunnel_type)
                # establish tunnel with all other tunnel_ip if l2_pop disabled
                # if l2_pop enabled, tunnel sync is processed by agent in q-agent-notifier-l2population_update consumer id
                if not self.l2_pop:
                    tunnels = details['tunnels']
                    for tunnel in tunnels:
                        if self.local_ip != tunnel['ip_address']:
                            tunnel_id = tunnel.get('id')
                            # Unlike the OVS plugin, ML2 doesn't return an id
                            # key. So use ip_address to form port name instead.
                            # Port name must be <=15 chars, so use shorter hex.
                            remote_ip = tunnel['ip_address']
                            remote_ip_hex = self.get_ip_in_hex(remote_ip)
                            if not tunnel_id and not remote_ip_hex:
                                continue
                            tun_name = '%s-%s' % (tunnel_type,
                                                  tunnel_id or remote_ip_hex)
                            # setup tunnel_port and related flows
                            self.setup_tunnel_port(tun_name,
                                                   tunnel['ip_address'],
                                                   tunnel_type)
        except Exception as e:
            LOG.debug(_("Unable to sync tunnel IP %(local_ip)s: %(e)s"),
                      {'local_ip': self.local_ip, 'e': e})
            resync = True
        return resync

def process_network_ports(self, port_info, ovs_restarted):
        resync_a = False
        resync_b = False
        # TODO(salv-orlando): consider a solution for ensuring notifications
        # are processed exactly in the same order in which they were
        # received. This is tricky because there are two notification
        # sources: the neutron server, and the ovs db monitor process
        # If there is an exception while processing security groups ports
        # will not be wired anyway, and a resync will be triggered
        # TODO(salv-orlando): Optimize avoiding applying filters unnecessarily
        # (eg: when there are no IP address changes)
        # 通过plugin_rpc到plugin查询安全组，然后通过sg_agent应用安全组
        self.sg_agent.setup_port_filters(port_info.get('added', set()),
                                         port_info.get('updated', set()))
        # VIF wiring needs to be performed always for 'new' devices.
        # For updated ports, re-wiring is not needed in most cases, but needs
        # to be performed anyway when the admin state of a device is changed.
        # A device might be both in the 'added' and 'updated'
        # list at the same time; avoid processing it twice.
        devices_added_updated = (port_info.get('added', set()) |
                                 port_info.get('updated', set()))
        if devices_added_updated:
            start = time.time()
            try:
                # 添加或更新的ports: 查询port详细信息后通知plugin port up/down，接着再port_bound/port_dead
                skipped_devices = self.treat_devices_added_or_updated(
                    devices_added_updated, ovs_restarted)
                LOG.debug(_("process_network_ports - iteration:%(iter_num)d -"
                            "treat_devices_added_or_updated completed. "
                            "Skipped %(num_skipped)d devices of "
                            "%(num_current)d devices currently available. "
                            "Time elapsed: %(elapsed).3f"),
                          {'iter_num': self.iter_num,
                           'num_skipped': len(skipped_devices),
                           'num_current': len(port_info['current']),
                           'elapsed': time.time() - start})
                # Update the list of current ports storing only those which
                # have been actually processed.
                port_info['current'] = (port_info['current'] -
                                        set(skipped_devices))
            except DeviceListRetrievalError:
                # Need to resync as there was an error with server
                # communication.
                LOG.exception(_("process_network_ports - iteration:%d - "
                                "failure while retrieving port details "
                                "from server"), self.iter_num)
                resync_a = True
        if 'removed' in port_info:
            start = time.time()
            # 删除的port：删除安全组，通知plugin port down, 并unbound local_vlan，
            resync_b = self.treat_devices_removed(port_info['removed'])
            LOG.debug(_("process_network_ports - iteration:%(iter_num)d -"
                        "treat_devices_removed completed in %(elapsed).3f"),
                      {'iter_num': self.iter_num,
                       'elapsed': time.time() - start})
        # If one of the above operations fails => resync with plugin
        return (resync_a | resync_b)

def main():
    """Main method for cleaning up OVS bridges.

    The utility cleans up the integration bridges used by Neutron.
    """

    conf = setup_conf()
    conf()
    config.setup_logging(conf)

    configuration_bridges = set([conf.ovs_integration_bridge,
                                 conf.external_network_bridge])
    ovs_bridges = set(ovs_lib.get_bridges(conf.AGENT.root_helper))
    available_configuration_bridges = configuration_bridges & ovs_bridges

    if conf.ovs_all_ports:
        bridges = ovs_bridges
    else:
        bridges = available_configuration_bridges

    # Collect existing ports created by Neutron on configuration bridges.
    # After deleting ports from OVS bridges, we cannot determine which
    # ports were created by Neutron, so port information is collected now.
    ports = collect_neutron_ports(available_configuration_bridges,
                                  conf.AGENT.root_helper)

    for bridge in bridges:
        LOG.info(_("Cleaning %s"), bridge)
        ovs = ovs_lib.OVSBridge(bridge, conf.AGENT.root_helper)
        ovs.delete_ports(all_ports=conf.ovs_all_ports)

    # Remove remaining ports created by Neutron (usually veth pair)
    delete_neutron_ports(ports, conf.AGENT.root_helper)

    LOG.info(_("OVS cleanup completed successfully"))