neutron中的QOS实现源码-service中的实现
notification_drivers文件夹
1、manager.py
主要实现了QosServiceNotificationDriverManager类，首先进行初始化，得到qos的drivers实例
def __init__(self):
self.notification_drivers = []
self._load_drivers(cfg.CONF.qos.notification_drivers)
根据传入的notification_drivers参数，得到实例instance，具体实现通过调用内部方法_load_driver_instance()
def _load_drivers(self, notification_drivers):
"""Load all the instances of the configured QoS notification drivers
:param notification_drivers: comma separated string
"""
if not notification_drivers:
raise SystemExit(_('A QoS driver must be specified'))
LOG.debug("Loading QoS notification drivers: %s", notification_drivers)
for notification_driver in notification_drivers:
driver_ins = self._load_driver_instance(notification_driver)
self.notification_drivers.append(driver_ins)
方法_load_driver_instance()调用类NeutronManager的load_class_for_provider()方法，对driver进行实例化。
def _load_driver_instance(self, notification_driver):
"""Returns an instance of the configured QoS notification driver
:returns: An instance of Driver for the QoS notification
"""
mgr = manager.NeutronManager
driver = mgr.load_class_for_provider(QOS_DRIVER_NAMESPACE,
notification_driver)
driver_instance = driver()
LOG.info(
_LI("Loading %(name)s (%(description)s) notification driver "
"for QoS plugin"),
{"name": notification_driver,
"description": driver_instance.get_description()})
return driver_instance
load_class_for_provider()方法中的实现过程，调用python中的类stevedore。根据namespace获得相应entry point组，然后根据plugin_provider调用相应的plugin插件
mgr = driver.DriverManager(namespace, plugin_provider)
plugin_class = mgr.driver
得到drivers的实例后就可以对其进行具体的操作了，包括：update_policy()、delete_policy()和create_policy()
def update_policy(self, context, qos_policy):
for driver in self.notification_drivers:
driver.update_policy(context, qos_policy)
def delete_policy(self, context, qos_policy):
for driver in self.notification_drivers:
driver.delete_policy(context, qos_policy)
def create_policy(self, context, qos_policy):
for driver in self.notification_drivers:
driver.create_policy(context, qos_policy)
2、message_queue.py
主要实现了类RpcQosServiceNotificationDriver，主要用来实现qos用于消息队列的driver。继承父类neutron.services.qos.notification_drivers.QosServiceNotificationDriverBase。
初始化实现了ResourcesPushRpcApi()类的实例化
self.notification_api = resources_rpc.ResourcesPushRpcApi()
registry.provide(_get_qos_policy_cb, resources.QOS_POLICY)
继承父类的push()方法
def update_policy(self, context, policy):
self.notification_api.push(context, policy, events.UPDATED)
push(self, context, resource, event_type)实现方法，ResourcesPushRpcApi()类主要将对象的更新状态信息push给receiver端的agent，通过消息队列的广播topic形式发送。
最终也是以一种cast的形式广播出去，这种并不需要接收端的反馈，push出去就不需要等待接收反馈了。
cctxt = self._prepare_object_fanout_context(resource)
dehydrated_resource = resource.obj_to_primitive()
cctxt.cast(context, 'push',
resource=dehydrated_resource,
event_type=event_type)
3、qos_base.py
主要包括类QosServiceNotificationDriverBase，里面全是抽象接口，具体需要继承的子类来实现
get_descriptioncreate_policyupdate_policydelete_policy
qos_consts.py
配置好关键字和参数，进行全局调用，RULE_TYPE_BANDWIDTH_LIMIT，VALID_RULE_TYPES，QOS_POLICY_ID
RULE_TYPE_BANDWIDTH_LIMIT = 'bandwidth_limit'
VALID_RULE_TYPES = [RULE_TYPE_BANDWIDTH_LIMIT]
QOS_POLICY_ID = 'qos_policy_id'
qos_plugin.py
主要定义了类QosPlugin，该类主要继承父类neutron.extensions.QoSPluginBase，实现了neutron QOS service端的plugin，为network和port提供qos参数
该类实现了neutron QOS 服务的plugin，提供network和port上的qos流量控制的plugin。
首先进行了初始化，实例化类QosServiceNotificationDriverManager()，再进行后续的操作。
self.notification_driver_manager = (
driver_mgr.QosServiceNotificationDriverManager())
policy的方法实现
方法create_policy()、update_policy()、delete_policy()、get_policy(),根据传入的参数policy或者policy_id进行相应的操作。
policy = policy_object.QosPolicy(context, **policy['policy'])
policy.create()
self.notification_driver_manager.create_policy(context, policy)
这里主要是实例化neutron.objects.qos.policy.QosPolicy()类，并调用create()、update()、delete()、get_by_id()方法，即是增删改查。具体来说就是操作底层的数据库，进行增删改查。
neutron.objects主要是和数据库层打交道的。
在neutron.objects.qos.policy.QosPolicy()类中，create()`方法实例化了session层的映射，将对象和数据库中的表格映射起来。
def create(self):
with db_api.autonested_transaction(self._context.session):
super(QosPolicy, self).create()
self.reload_rules()
def delete(self):
models = (
('network', self.network_binding_model),
('port', self.port_binding_model)
)
with db_api.autonested_transaction(self._context.session):
for object_type, model in models:
binding_db_obj = db_api.get_object(self._context, model,
policy_id=self.id)
if binding_db_obj:
raise exceptions.QosPolicyInUse(
policy_id=self.id,
object_type=object_type,
object_id=binding_db_obj['%s_id' % object_type])
super(QosPolicy, self).delete()
def get_by_id(cls, context, id):
admin_context = context.elevated()
with db_api.autonested_transaction(admin_context.session):
policy_obj = super(QosPolicy, cls).get_by_id(admin_context, id)
if (not policy_obj or
not cls._is_policy_accessible(context, policy_obj)):
return
policy_obj.reload_rules()
return policy_obj
rule的方法实现
分析完policy的配置，下面来看rule的具体操作，实现方法包括：create_policy_bandwidth_limit_rule()、update_policy_bandwidth_limit_rule()、delete_policy_bandwidth_limit_rule()、get_policy_bandwidth_limit_rule()、get_policy_bandwidth_limit_rules()
create_policy_bandwidth_limit_rule()方法
先实例化session的映射对象，将数据库的表和object进行映射，然后根据policy_id以及传入的参数bandwidth_limit_rule，先从neutron.object中实例化session,然后在数据库中进行表的添加。
数据库添加完成后，在对policy进行update一下，保证rule的实时性。
policy = self._get_policy_obj(context, policy_id)
rule = rule_object.QosBandwidthLimitRule(
context, qos_policy_id=policy_id,
**bandwidth_limit_rule['bandwidth_limit_rule'])
rule.create()
policy.reload_rules()
self.notification_driver_manager.update_policy(context, policy)
neutron.objects.qos.QosRule的子类QosBandwidthLimitRule中实现的步骤，可见直接调用neutorn.db.qos.modles操作数据库
db_model = qos_db_model.QosBandwidthLimitRule
neutorn.db.qos.modles中的类QosBandwidthLimitRule实现过程，
qos_policy_id = sa.Column(sa.String(36),
sa.ForeignKey('qos_policies.id',
ondelete='CASCADE'),
nullable=False,
unique=True)
max_kbps = sa.Column(sa.Integer)
max_burst_kbps = sa.Column(sa.Integer)
这就是在数据库中对表数据的实际操作。操作结束再对policy更新一下rule
update_policy_bandwidth_limit_rule()和delete_policy_bandwidth_limit_rule()实现过程类似，也是对后台数据库进行操作然后reload_rules一下。
get_policy_bandwidth_limit_rule()
调用方式也比较类似，主要通过neutorn.objects来对session进行映射实例化，然后从后台的数据库中进行查询
self._get_policy_obj(context, policy_id)
rule = rule_object.QosBandwidthLimitRule.get_by_id(
context, rule_id)