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本文次要钻研一下dubbo-go的DefaultHealthChecker

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}
  • DefaultHealthChecker定义了outStandingRequestConutLimit、requestSuccessiveFailureThreshold、circuitTrippedTimeoutFactor属性

NewDefaultHealthChecker

dubbo-go-v1.4.2/cluster/router/healthcheck/default_health_check.go

// NewDefaultHealthChecker constructs a new DefaultHealthChecker based on the urlfunc 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)),    }}
  • NewDefaultHealthChecker实例化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 requestfunc (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}
  • IsHealthy办法通过protocol.GetURLStatus(invoker.GetUrl())获取urlStatus，之后依据c.isCircuitBreakerTripped(urlStatus)或者urlStatus.GetActive() > c.GetOutStandingRequestConutLimit()判断是否处于circuitbreaker tripped状态

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 requestfunc (c *DefaultHealthChecker) isCircuitBreakerTripped(status *protocol.RPCStatus) bool {    circuitBreakerTimeout := c.getCircuitBreakerTimeout(status)    currentTime := protocol.CurrentTimeMillis()    if circuitBreakerTimeout <= 0 {        return false    }    return circuitBreakerTimeout > currentTime}
  • isCircuitBreakerTripped办法通过c.getCircuitBreakerTimeout(status)获取circuitBreakerTimeout，若circuitBreakerTimeout小于等于0返回false，否则判断circuitBreakerTimeout是否大于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 millisecondfunc (c *DefaultHealthChecker) getCircuitBreakerTimeout(status *protocol.RPCStatus) int64 {    sleepWindow := c.getCircuitBreakerSleepWindowTime(status)    if sleepWindow <= 0 {        return 0    }    return status.GetLastRequestFailedTimestamp() + sleepWindow}
  • getCircuitBreakerTimeout办法先获取sleepWindow，若sleepWindow小于等于0则返回0，否则返回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 millisecondfunc (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)}
  • getCircuitBreakerSleepWindowTime办法通过比照status.GetSuccessiveRequestFailureCount()及c.GetRequestSuccessiveFailureThreshold()计算diff，进而依据c.GetCircuitTrippedTimeoutFactor()计算sleepWindow

小结

DefaultHealthChecker定义了outStandingRequestConutLimit、requestSuccessiveFailureThreshold、circuitTrippedTimeoutFactor属性；IsHealthy办法通过protocol.GetURLStatus(invoker.GetUrl())获取urlStatus，之后依据c.isCircuitBreakerTripped(urlStatus)或者urlStatus.GetActive() > c.GetOutStandingRequestConutLimit()判断是否处于circuitbreaker tripped状态

doc

  • default_health_check