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@peterbourgon
Created August 14, 2015 17:54
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package main
import (
"errors"
"log"
"github.com/afex/hystrix-go/hystrix"
)
func main() {
log.SetFlags(0)
const (
commandName = "my-endpoint"
errorPercent = 5
maxConcurrent = 1000
)
hystrix.ConfigureCommand(commandName, hystrix.CommandConfig{
ErrorPercentThreshold: errorPercent,
MaxConcurrentRequests: maxConcurrent,
})
var (
primeWith = hystrix.DefaultVolumeThreshold * 2
shouldPass = func(n int) bool { return (float64(n) / float64(primeWith+n)) <= (float64(errorPercent-1) / 100.0) }
)
var myErr error
run := func() error { return myErr }
log.Printf("priming with %d successful requests", primeWith)
for i := 0; i < primeWith; i++ {
if err := hystrix.Do(commandName, run, nil); err != myErr {
log.Fatalf("initial request %d failed: %v", i+1, err)
}
}
log.Printf("switching to errors...")
myErr = errors.New("kaboom")
log.Printf("now the next few requests should give us our error: %v", myErr)
for i := 0; shouldPass(i); i++ {
if err := hystrix.Do(commandName, run, nil); err != myErr {
log.Fatalf("post-error request %d failed: %v", i+1, err)
}
log.Printf("got expected error %d", i+1)
}
log.Printf("the circuit should have opened by now")
for i := 0; i < 5; i++ {
if err := hystrix.Do(commandName, run, nil); err != hystrix.ErrCircuitOpen {
log.Fatalf("got unexpected error at request %d: %v", i+1, err)
}
log.Printf("got expected error: %v", hystrix.ErrCircuitOpen)
}
log.Printf("everything works as expected")
}
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