initial import

example/breaker/main.go

@@ -0,0 +1,139 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"os"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"zero/core/breaker"
+	"zero/core/lang"
+
+	"gopkg.in/cheggaaa/pb.v1"
+)
+
+const (
+	duration        = time.Minute * 5
+	breakRange      = 20
+	workRange       = 50
+	requestInterval = time.Millisecond
+	// multiply to make it visible in plot
+	stateFator = float64(time.Second/requestInterval) / 2
+)
+
+type (
+	server struct {
+		state int32
+	}
+
+	metric struct {
+		calls int64
+	}
+)
+
+func (m *metric) addCall() {
+	atomic.AddInt64(&m.calls, 1)
+}
+
+func (m *metric) reset() int64 {
+	return atomic.SwapInt64(&m.calls, 0)
+}
+
+func newServer() *server {
+	return &server{}
+}
+
+func (s *server) serve(m *metric) bool {
+	m.addCall()
+	return atomic.LoadInt32(&s.state) == 1
+}
+
+func (s *server) start() {
+	go func() {
+		r := rand.New(rand.NewSource(time.Now().UnixNano()))
+		var state int32
+		for {
+			var v int32
+			if state == 0 {
+				v = r.Int31n(breakRange)
+			} else {
+				v = r.Int31n(workRange)
+			}
+			time.Sleep(time.Second * time.Duration(v+1))
+			state ^= 1
+			atomic.StoreInt32(&s.state, state)
+		}
+	}()
+}
+
+func runBreaker(s *server, br breaker.Breaker, duration time.Duration, m *metric) {
+	ticker := time.NewTicker(requestInterval)
+	defer ticker.Stop()
+	done := make(chan lang.PlaceholderType)
+
+	go func() {
+		time.Sleep(duration)
+		close(done)
+	}()
+
+	for {
+		select {
+		case <-ticker.C:
+			_ = br.Do(func() error {
+				if s.serve(m) {
+					return nil
+				} else {
+					return breaker.ErrServiceUnavailable
+				}
+			})
+		case <-done:
+			return
+		}
+	}
+}
+
+func main() {
+	srv := newServer()
+	srv.start()
+
+	gb := breaker.NewBreaker()
+	fp, err := os.Create("result.csv")
+	lang.Must(err)
+	defer fp.Close()
+	fmt.Fprintln(fp, "seconds,state,googleCalls,netflixCalls")
+
+	var gm, nm metric
+	go func() {
+		ticker := time.NewTicker(time.Second)
+		defer ticker.Stop()
+		var seconds int
+		for range ticker.C {
+			seconds++
+			gcalls := gm.reset()
+			ncalls := nm.reset()
+			fmt.Fprintf(fp, "%d,%.2f,%d,%d\n",
+				seconds, float64(atomic.LoadInt32(&srv.state))*stateFator, gcalls, ncalls)
+		}
+	}()
+
+	var waitGroup sync.WaitGroup
+	waitGroup.Add(1)
+	go func() {
+		runBreaker(srv, gb, duration, &gm)
+		waitGroup.Done()
+	}()
+
+	go func() {
+		bar := pb.New(int(duration / time.Second)).Start()
+		ticker := time.NewTicker(time.Second)
+		defer ticker.Stop()
+		for range ticker.C {
+			bar.Increment()
+		}
+		bar.Finish()
+	}()
+
+	waitGroup.Wait()
+}

example/breaker/plot.py

@@ -0,0 +1,15 @@
+import click
+import pandas as pd
+import matplotlib.pyplot as plt
+
+
+@click.command()
+@click.option("--csv", default="result.csv")
+def main(csv):
+    df = pd.read_csv(csv, index_col="seconds")
+    df.plot()
+    plt.show()
+
+
+if __name__ == "__main__":
+    main()