Talk about dubo-go’s DefaultHealthChecker

sequence

This paper focuses on the DefaultHealthChecker of Dubo-Go

DefaultHealthChecker

Dubbo – go – v1.4.2 / cluster/router/healthcheck/default_health_check. Go

func init() { extension.SethealthChecker(constant.DEFAULT_HEALTH_CHECKER, NewDefaultHealthChecker) } // DefaultHealthChecker is the default implementation of HealthChecker, which determines the health status of // the invoker based on the number of successive bad request and the current active request. type DefaultHealthChecker struct { // the limit of outstanding request outStandingRequestConutLimit int32 // the threshold of successive-failure-request requestSuccessiveFailureThreshold int32 // value of circuit-tripped  timeout factor circuitTrippedTimeoutFactor int32 }Copy the code

• DefaultHealthChecker defines outStandingRequestConutLimit, requestSuccessiveFailureThreshold, circuitTrippedTimeoutFactor properties

NewDefaultHealthChecker

Dubbo – go – v1.4.2 / cluster/router/healthcheck/default_health_check. Go

// NewDefaultHealthChecker constructs a new DefaultHealthChecker based on the url func NewDefaultHealthChecker(url *common.URL) router.HealthChecker { return &DefaultHealthChecker{ outStandingRequestConutLimit: int32(url.GetParamInt(constant.OUTSTANDING_REQUEST_COUNT_LIMIT_KEY, math.MaxInt32)), requestSuccessiveFailureThreshold: int32(url.GetParamInt(constant.SUCCESSIVE_FAILED_REQUEST_THRESHOLD_KEY, constant.DEFAULT_SUCCESSIVE_FAILED_REQUEST_MAX_DIFF)), circuitTrippedTimeoutFactor: int32(url.GetParamInt(constant.CIRCUIT_TRIPPED_TIMEOUT_FACTOR_KEY, constant.DEFAULT_CIRCUIT_TRIPPED_TIMEOUT_FACTOR)), }}Copy the code

• NewDefaultHealthChecker instantiates DefaultHealthChecker

IsHealthy

Dubbo – go – v1.4.2 / cluster/router/healthcheck/default_health_check. Go

// IsHealthy evaluates the healthy state on the given Invoker based on the number of successive bad request
// and the current active request
func (c *DefaultHealthChecker) IsHealthy(invoker protocol.Invoker) bool {
	urlStatus := protocol.GetURLStatus(invoker.GetUrl())
	if c.isCircuitBreakerTripped(urlStatus) || urlStatus.GetActive() > c.GetOutStandingRequestConutLimit() {
		logger.Debugf("Invoker [%s] is currently in circuitbreaker tripped state", invoker.GetUrl().Key())
		return false
	}
	return true
}
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• IsHealthy method by protocol. GetURLStatus (invoker. GetUrl ()) get urlStatus, after according to c.i sCircuitBreakerTripped (urlStatus) orurlStatus.GetActive() > c.GetOutStandingRequestConutLimit()Determine whether circuitbreaker tripped

isCircuitBreakerTripped

Dubbo – go – v1.4.2 / cluster/router/healthcheck/default_health_check. Go

// isCircuitBreakerTripped determine whether the invoker is in the tripped state by the number of successive bad request  func (c *DefaultHealthChecker) isCircuitBreakerTripped(status *protocol.RPCStatus) bool { circuitBreakerTimeout := c.getCircuitBreakerTimeout(status) currentTime := protocol.CurrentTimeMillis() if circuitBreakerTimeout <= 0 { return false } return circuitBreakerTimeout > currentTime }Copy the code

• Be sad etCircuitBreakerTimeout chtistina georgina rossetti.british poetess isCircuitBreakerTripped method through get circuitBreakerTimeout (status), if circuitBreakerTimeout less than or equal to 0 returns false, Otherwise, check whether circuitBreakerTimeout is greater than currentTime

getCircuitBreakerTimeout

Dubbo – go – v1.4.2 / cluster/router/healthcheck/default_health_check. Go

// getCircuitBreakerTimeout get the timestamp recovered from tripped state, the unit is millisecond
func (c *DefaultHealthChecker) getCircuitBreakerTimeout(status *protocol.RPCStatus) int64 {
	sleepWindow := c.getCircuitBreakerSleepWindowTime(status)
	if sleepWindow <= 0 {
		return 0
	}
	return status.GetLastRequestFailedTimestamp() + sleepWindow
}
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• GetCircuitBreakerTimeout method to obtain sleepWindow, if sleepWindow less than or equal to zero, it returns 0. Otherwise returns the status GetLastRequestFailedTimestamp () + sleepWindow

getCircuitBreakerSleepWindowTime

Dubbo – go – v1.4.2 / cluster/router/healthcheck/default_health_check. Go

// getCircuitBreakerSleepWindowTime get the sleep window time of invoker, the unit is millisecond
func (c *DefaultHealthChecker) getCircuitBreakerSleepWindowTime(status *protocol.RPCStatus) int64 {

	successiveFailureCount := status.GetSuccessiveRequestFailureCount()
	diff := successiveFailureCount - c.GetRequestSuccessiveFailureThreshold()
	if diff < 0 {
		return 0
	} else if diff > constant.DEFAULT_SUCCESSIVE_FAILED_REQUEST_MAX_DIFF {
		diff = constant.DEFAULT_SUCCESSIVE_FAILED_REQUEST_MAX_DIFF
	}
	sleepWindow := (1 << diff) * c.GetCircuitTrippedTimeoutFactor()
	if sleepWindow > constant.MAX_CIRCUIT_TRIPPED_TIMEOUT_IN_MS {
		sleepWindow = constant.MAX_CIRCUIT_TRIPPED_TIMEOUT_IN_MS
	}
	return int64(sleepWindow)
}
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• GetCircuitBreakerSleepWindowTime method by comparing the status. GetSuccessiveRequestFailureCount be sad etRequestSuccessiveFailureThreshold chtistina georgina rossetti.british poetess () and () Be sad etCircuitTrippedTimeoutFactor chtistina georgina rossetti.british poetess computing diff, then according to the calculation sleepWindow ()

summary

DefaultHealthChecker defines outStandingRequestConutLimit, requestSuccessiveFailureThreshold, circuitTrippedTimeoutFactor attributes; IsHealthy obtains urlStatus from protocol.geturlStatus (invoker.geturl ()). Then according to the c.i sCircuitBreakerTripped (urlStatus) or urlStatus. GetActive () > C.G etOutStandingRequestConutLimit () determine whether in the circuitbreaker tripped state

doc

• default_health_check