add comments

cluster/router/condition/default_health_check.go

@@ -28,14 +28,19 @@ func init() {
 	extension.SethealthChecker(DEFAULT_HEALTH_CHECKER, NewDefaultHealthChecker)
 }
 
-// DefaultHealthChecker is the default
+// 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 {
+	// OutStandingRequestConutLimit
 	OutStandingRequestConutLimit int32
-	// the circuitbreaker threshold
+	// RequestSuccessiveFailureThreshold
 	RequestSuccessiveFailureThreshold int32
-	CircuitTrippedTimeoutFactor       int32
+	// RequestSuccessiveFailureThreshold
+	CircuitTrippedTimeoutFactor int32
 }
 
+// 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.OutStandingRequestConutLimit {
@@ -44,6 +49,8 @@ func (c *DefaultHealthChecker) IsHealthy(invoker protocol.Invoker) bool {
 	}
 	return true
 }
+
+// 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()
@@ -53,6 +60,7 @@ func (c *DefaultHealthChecker) isCircuitBreakerTripped(status *protocol.RPCStatu
 	return circuitBreakerTimeout > currentTime
 }
 
+// getCircuitBreakerTimeout get the timestamp recovered from tripped state
 func (c *DefaultHealthChecker) getCircuitBreakerTimeout(status *protocol.RPCStatus) int64 {
 	sleepWindow := c.getCircuitBreakerSleepWindowTime(status)
 	if sleepWindow <= 0 {
@@ -61,6 +69,7 @@ func (c *DefaultHealthChecker) getCircuitBreakerTimeout(status *protocol.RPCStat
 	return status.GetLastRequestFailedTimestamp() + sleepWindow
 }
 
+// getCircuitBreakerSleepWindowTime get the sleep window time of invoker
 func (c *DefaultHealthChecker) getCircuitBreakerSleepWindowTime(status *protocol.RPCStatus) int64 {
 
 	successiveFailureCount := status.GetSuccessiveRequestFailureCount()
@@ -77,6 +86,7 @@ func (c *DefaultHealthChecker) getCircuitBreakerSleepWindowTime(status *protocol
 	return int64(sleepWindow)
 }
 
+// NewDefaultHealthChecker constructs a new DefaultHealthChecker based on the url
 func NewDefaultHealthChecker(url *common.URL) router.HealthChecker {
 	return &DefaultHealthChecker{
 		OutStandingRequestConutLimit:      int32(url.GetParamInt(OUTSTANDING_REQUEST_COUNT_LIMIT_KEY, math.MaxInt32)),

cluster/router/condition/factory.go

@@ -27,6 +27,7 @@ import (
 func init() {
 	extension.SetRouterFactory(constant.ConditionRouterName, newConditionRouterFactory)
 	extension.SetRouterFactory(constant.ConditionAppRouterName, newAppRouterFactory)
+	extension.SetRouterFactory(constant.HealthCheckRouterName, newHealthCheckRouteFactory)
 }
 
 // ConditionRouterFactory Condition router factory

cluster/router/condition/health_check_route.go

@@ -12,12 +12,14 @@ const (
 	HEALTH_ROUTE_ENABLED_KEY = "health.route.enabled"
 )
 
+// HealthCheckRouter provides a health-first routing mechanism through HealthChecker
 type HealthCheckRouter struct {
 	url     *common.URL
 	enabled bool
 	checker router.HealthChecker
 }
 
+// NewHealthCheckRouter construct an HealthCheckRouter via url
 func NewHealthCheckRouter(url *common.URL) (router.Router, error) {
 	r := &HealthCheckRouter{}
 	r.url = url
@@ -29,16 +31,19 @@ func NewHealthCheckRouter(url *common.URL) (router.Router, error) {
 	return r, nil
 }
 
+// Route gets a list of healthy invoker
 func (r *HealthCheckRouter) Route(invokers []protocol.Invoker, url *common.URL, invocation protocol.Invocation) []protocol.Invoker {
 	if !r.enabled {
 		return invokers
 	}
 	var healthyInvokers []protocol.Invoker
+	// Add healthy invoker to the list
 	for _, invoker := range invokers {
 		if r.checker.IsHealthy(invoker) {
 			healthyInvokers = append(healthyInvokers, invoker)
 		}
 	}
+	// If all Invoke are considered unhealthy, downgrade to all inovker
 	if len(healthyInvokers) == 0 {
 		logger.Warnf(" Now all invokers are unhealthy, so downgraded to all! Service: [%s]", url.ServiceKey())
 		return invokers
@@ -47,6 +52,7 @@ func (r *HealthCheckRouter) Route(invokers []protocol.Invoker, url *common.URL,
 	}
 }
 
+// Priority
 func (r *HealthCheckRouter) Priority() int64 {
 	return 0
 }
@@ -56,6 +62,7 @@ func (r *HealthCheckRouter) URL() common.URL {
 	return *r.url
 }
 
+// HealthyChecker returns the HealthChecker bound to this HealthCheckRouter
 func (r *HealthCheckRouter) HealthyChecker() router.HealthChecker {
 	return r.checker
 }

cluster/router/health_checker.go

@@ -4,6 +4,8 @@ import (
 	"github.com/apache/dubbo-go/protocol"
 )
 
+// HealthChecker is used to determine whether the invoker is healthy or not
 type HealthChecker interface {
+	// IsHealthy evaluates the healthy state on the given Invoker
 	IsHealthy(invoker protocol.Invoker) bool
 }

common/constant/key.go

@@ -159,6 +159,7 @@ const (
 	ConditionAppRouterName = "app"
 	// ListenableRouterName Specify listenable router name
 	ListenableRouterName = "listenable"
+	HealthCheckRouterName = "health_check"
 
 	// ConditionRouterRuleSuffix Specify condition router suffix
 	ConditionRouterRuleSuffix = ".condition-router"

common/extension/health_checker.go

@@ -9,10 +9,12 @@ var (
 	healthCheckers = make(map[string]func(url *common.URL) router.HealthChecker)
 )
 
+// SethealthChecker set the HealthChecker with name
 func SethealthChecker(name string, fcn func(url *common.URL) router.HealthChecker) {
 	healthCheckers[name] = fcn
 }
 
+// GetHealthChecker get the HealthChecker with name
 func GetHealthChecker(name string, url *common.URL) router.HealthChecker {
 	if healthCheckers[name] == nil {
 		panic("healthCheckers for " + name + " is not existing, make sure you have import the package.")