Throttling with bug

throttling/rateLimit.go

@@ -0,0 +1,56 @@
+package throttling
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"time"
+)
+
+const rateLimit = time.Second * 3 // a call each 3 second
+
+// Client is an interface that calls something with a payload.
+type Client interface {
+	Call(*Payload)
+}
+
+// Payload is some payload a Client would send in a call.
+type Payload struct {
+	ClientResult string
+	W            http.ResponseWriter
+	R            *http.Request
+}
+
+// CallFunction allows burst rate limiting client calls with the
+// payloads.
+func CallFunction(ctx context.Context, client Client, payload *Payload, throttle <-chan time.Time) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	<-throttle // rate limit our client calls
+	client.Call(payload)
+}
+
+func CreateThrottle(ctx context.Context, burstLimit int) <-chan time.Time {
+	throttle := make(chan time.Time, burstLimit)
+	for i := 0; i < burstLimit; i++ {
+		throttle <- time.Now()
+	}
+
+	go func() {
+		ticker := time.NewTicker(rateLimit)
+		defer ticker.Stop()
+		for t := range ticker.C {
+			select {
+			case throttle <- t:
+			case <-ctx.Done():
+				{
+					fmt.Println("Ticker done")
+					return // exit goroutine when surrounding function returns
+				}
+			}
+		}
+	}()
+
+	return throttle
+}

throttling/rateLimit_test.go

@@ -0,0 +1,32 @@
+package throttling
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+)
+
+func TestCallFunction(t *testing.T) {
+	client := &Callable{}
+	// create context for app
+	ctx := context.Background()
+
+	fmt.Println("Starting")
+	throttle := CreateThrottle(ctx, 2)
+	CallFunction(ctx, client, &Payload{}, throttle)
+	CallFunction(ctx, client, &Payload{}, throttle)
+	CallFunction(ctx, client, &Payload{}, throttle)
+	time.Sleep(2 * time.Second)
+	fmt.Println("Continuing")
+	CallFunction(ctx, client, &Payload{}, throttle)
+	CallFunction(ctx, client, &Payload{}, throttle)
+	CallFunction(ctx, client, &Payload{}, throttle)
+}
+
+type Callable struct {
+}
+
+func (c *Callable) Call(p *Payload) {
+	fmt.Println("Called with payload")
+}