聊聊dubbo-go的HystrixFilter

序

本文主要研究一下dubbo-go的HystrixFilter

HystrixFilter

dubbo-go-v1.4.2/filter/filter_impl/hystrix_filter.go

// HystrixFilter ...
type HystrixFilter struct {
	COrP     bool //true for consumer
	res      map[string][]*regexp.Regexp
	ifNewMap sync.Map
}

HystrixFilter定义了COrP、res、ifNewMap属性

Invoke

dubbo-go-v1.4.2/filter/filter_impl/hystrix_filter.go

// Invoke ...
func (hf *HystrixFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {
	cmdName := fmt.Sprintf("%s&method=%s", invoker.GetUrl().Key(), invocation.MethodName())

	// Do the configuration if the circuit breaker is created for the first time
	if _, load := hf.ifNewMap.LoadOrStore(cmdName, true); !load {
		configLoadMutex.Lock()
		filterConf := getConfig(invoker.GetUrl().Service(), invocation.MethodName(), hf.COrP)
		for _, ptn := range filterConf.Error {
			reg, err := regexp.Compile(ptn)
			if err != nil {
				logger.Warnf("[Hystrix Filter]Errors occurred parsing error omit regexp: %s, %v", ptn, err)
			} else {
				if hf.res == nil {
					hf.res = make(map[string][]*regexp.Regexp)
				}
				hf.res[invocation.MethodName()] = append(hf.res[invocation.MethodName()], reg)
			}
		}
		hystrix.ConfigureCommand(cmdName, hystrix.CommandConfig{
			Timeout:                filterConf.Timeout,
			MaxConcurrentRequests:  filterConf.MaxConcurrentRequests,
			SleepWindow:            filterConf.SleepWindow,
			ErrorPercentThreshold:  filterConf.ErrorPercentThreshold,
			RequestVolumeThreshold: filterConf.RequestVolumeThreshold,
		})
		configLoadMutex.Unlock()
	}
	configLoadMutex.RLock()
	_, _, err := hystrix.GetCircuit(cmdName)
	configLoadMutex.RUnlock()
	if err != nil {
		logger.Errorf("[Hystrix Filter]Errors occurred getting circuit for %s , will invoke without hystrix, error is: ", cmdName, err)
		return invoker.Invoke(ctx, invocation)
	}
	logger.Infof("[Hystrix Filter]Using hystrix filter: %s", cmdName)
	var result protocol.Result
	_ = hystrix.Do(cmdName, func() error {
		result = invoker.Invoke(ctx, invocation)
		err := result.Error()
		if err != nil {
			result.SetError(NewHystrixFilterError(err, false))
			for _, reg := range hf.res[invocation.MethodName()] {
				if reg.MatchString(err.Error()) {
					logger.Debugf("[Hystrix Filter]Error in invocation but omitted in circuit breaker: %v; %s", err, cmdName)
					return nil
				}
			}
		}
		return err
	}, func(err error) error {
		//Return error and if it is caused by hystrix logic, so that it can be handled by previous filters.
		_, ok := err.(hystrix.CircuitError)
		logger.Debugf("[Hystrix Filter]Hystrix health check counted, error is: %v, failed by hystrix: %v; %s", err, ok, cmdName)
		result = &protocol.RPCResult{}
		result.SetResult(nil)
		result.SetError(NewHystrixFilterError(err, ok))
		return err
	})
	return result
}

Invoke方法首先通过hf.ifNewMap.LoadOrStore判断该cmdName的circuit breaker是否已经创建，还没有创建的话，会通过getConfig获取filterConf，给指定的invocation.MethodName()创建reg，之后通过hystrix.ConfigureCommand进行配置；之后通过hystrix.GetCircuit(cmdName)获取circuit，然后执行hystrix.Do，在该func里头执行invoker.Invoke(ctx, invocation)

OnResponse

dubbo-go-v1.4.2/filter/filter_impl/hystrix_filter.go

// OnResponse ...
func (hf *HystrixFilter) OnResponse(ctx context.Context, result protocol.Result, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {
	return result
}

OnResponse方法目前直接返回result

GetHystrixFilterConsumer

dubbo-go-v1.4.2/filter/filter_impl/hystrix_filter.go

// GetHystrixFilterConsumer ...
func GetHystrixFilterConsumer() filter.Filter {
	//When first called, load the config in
	consumerConfigOnce.Do(func() {
		if err := initHystrixConfigConsumer(); err != nil {
			logger.Warnf("[Hystrix Filter]Config load failed for consumer, error is: %v , will use default", err)
		}
	})
	return &HystrixFilter{COrP: true}
}

GetHystrixFilterConsumer创建的HystrixFilter的COrP属性为true

GetHystrixFilterProvider

dubbo-go-v1.4.2/filter/filter_impl/hystrix_filter.go

// GetHystrixFilterProvider ...
func GetHystrixFilterProvider() filter.Filter {
	providerConfigOnce.Do(func() {
		if err := initHystrixConfigProvider(); err != nil {
			logger.Warnf("[Hystrix Filter]Config load failed for provider, error is: %v , will use default", err)
		}
	})
	return &HystrixFilter{COrP: false}
}

GetHystrixFilterProvider创建的HystrixFilter的COrP属性为false

initHystrixConfigConsumer

dubbo-go-v1.4.2/filter/filter_impl/hystrix_filter.go

func initHystrixConfigConsumer() error {
	if config.GetConsumerConfig().FilterConf == nil {
		return perrors.Errorf("no config for hystrix")
	}
	filterConfig := config.GetConsumerConfig().FilterConf.(map[interface{}]interface{})[HYSTRIX]
	if filterConfig == nil {
		return perrors.Errorf("no config for hystrix")
	}
	hystrixConfByte, err := yaml.Marshal(filterConfig)
	if err != nil {
		return err
	}
	err = yaml.Unmarshal(hystrixConfByte, confConsumer)
	if err != nil {
		return err
	}
	return nil
}

initHystrixConfigConsumer会根据config.GetConsumerConfig().FilterConf的filterConfig来创建confConsumer

initHystrixConfigProvider

dubbo-go-v1.4.2/filter/filter_impl/hystrix_filter.go

func initHystrixConfigProvider() error {
	if config.GetProviderConfig().FilterConf == nil {
		return perrors.Errorf("no config for hystrix")
	}
	filterConfig := config.GetConsumerConfig().FilterConf.(map[interface{}]interface{})[HYSTRIX]
	if filterConfig == nil {
		return perrors.Errorf("no config for hystrix")
	}
	hystrixConfByte, err := yaml.Marshal(filterConfig)
	if err != nil {
		return err
	}
	err = yaml.Unmarshal(hystrixConfByte, confProvider)
	if err != nil {
		return err
	}
	return nil
}

initHystrixConfigProvider方法根据filterConfig来创建confProvider

小结

HystrixFilter的Invoke方法首先通过hf.ifNewMap.LoadOrStore判断该cmdName的circuit breaker是否已经创建，还没有创建的话，会通过getConfig获取filterConf，给指定的invocation.MethodName()创建reg，之后通过hystrix.ConfigureCommand进行配置；之后通过hystrix.GetCircuit(cmdName)获取circuit，然后执行hystrix.Do，在该func里头执行invoker.Invoke(ctx, invocation)

doc

hystrix_filter

来源：oschina

链接：https://my.oschina.net/go4it/blog/4411055

标签

hystrix