diff --git a/gomore/circuit_breaker/circuit_breaker_test.go b/gomore/circuit_breaker/circuit_breaker_test.go new file mode 100644 index 0000000..355c9e4 --- /dev/null +++ b/gomore/circuit_breaker/circuit_breaker_test.go @@ -0,0 +1,57 @@ +package circuit + +import ( + "context" + "time" +) + +type State int + +const ( + UnknownState State = iota + FailureState + SuccessState +) + +type Counter interface { + Count(State) + ConsecutiveFailures() uint32 + LastActivity() time.Time + Reset() +} + +type Circuit func(context.Context) error + +func Breaker(c Circuit, failureThreshold uint32) Circuit { + cnt := NewCounter() + + return func(ctx context) error { + if cnt.ConsecutiveFailures() >= failureThreshold { + canRetry := func(cnt Counter) { + backoffLevel := Cnt.ConsecutiveFailures() - failureThreshold + + // Calculates when should the circuit breaker resume propagating requests + // to the service + shouldRetryAt := cnt.LastActivity().Add(time.Seconds * 2 << backoffLevel) + + return time.Now().After(shouldRetryAt) + } + + if !canRetry(cnt) { + // Fails fast instead of propagating requests to the circuit since + // not enough time has passed since the last failure to retry + return ErrServiceUnavailable + } + } + + // Unless the failure threshold is exceeded the wrapped service mimics the + // old behavior and the difference in behavior is seen after consecutive failures + if err := c(ctx); err != nil { + cnt.Count(FailureState) + return err + } + + cnt.Count(SuccessState) + return nil + } +} diff --git a/gomore/rate_limiting/rate_limiting_test.go b/gomore/rate_limiting/rate_limiting_test.go new file mode 100644 index 0000000..57f10df --- /dev/null +++ b/gomore/rate_limiting/rate_limiting_test.go @@ -0,0 +1,105 @@ +package ratelimit + +import ( + "fmt" + "testing" + "time" +) + +/* + +Rate limiting is an very important mechanism +With limiting you can controll resource utilization and maintain quality of service. +Go supports rate limiting by using goroutines, channels, and tickers. +*/ + +func TestRateLimiting(t *testing.T) { + requests := make(chan int, 5) + for i := 1; i <= 5; i++ { + requests <- i + } + close(requests) + + limiter := time.Tick(200 * time.Millisecond) + + for req := range requests { + <-limiter + t.Log("Sev request by 2000 Millisecond", req, time.Now()) + } + + burstyLimiter := make(chan struct{}, 3) + + //init burstyLimiter + for i := 0; i < 3; i++ { + burstyLimiter <- struct{}{} + } + go func() { + for { + select { + case <-time.Tick(200 * time.Millisecond): + burstyLimiter <- struct{}{} + } + + } + }() + + //max request queue + burstyRequestsQueue := make(chan int, 5) + for i := 1; i <= 5; i++ { + burstyRequestsQueue <- i + } + close(burstyRequestsQueue) + + for req := range burstyRequestsQueue { + <-burstyLimiter + if len(burstyLimiter) > 0 { + fmt.Println("working current in bursting status!") + } else { + fmt.Println("working current in normal status!") + } + fmt.Println("request handled", req, time.Now()) + } + + rateLimiting() + +} + +func rateLimiting() { + + requests := make(chan int, 5) + for i := 1; i <= 5; i++ { + requests <- i + } + close(requests) + + limiter := time.Tick(200 * time.Millisecond) + + for req := range requests { + <-limiter + fmt.Println("request", req, time.Now()) + } + + //突发限流器 + burstyLimiter := make(chan time.Time, 3) + + for i := 0; i < 3; i++ { + burstyLimiter <- time.Now() + } + + go func() { + for t := range time.Tick(200 * time.Millisecond) { + burstyLimiter <- t + } + }() + + //请求队列 + burstyRequests := make(chan int, 5) + for i := 1; i <= 5; i++ { + burstyRequests <- i + } + close(burstyRequests) + for req := range burstyRequests { + <-burstyLimiter + fmt.Println("request", req, time.Now()) + } +}