// RateLimit creates a throttler that limits the number of requests allowed
// in a certain time window defined by the Quota q. The q parameter specifies
// the requests per time window, and it is silently set to at least 1 request
// and at least a 1 second window if it is less than that. The time window
// starts when the first request is made outside an existing window. Fractions
// of seconds are not supported, they are truncated.
//
// The vary parameter indicates what criteria should be used to group requests
// for which the limit must be applied (ex.: rate limit based on the remote address).
// See varyby.go for the various options.
//
// The specified store is used to keep track of the request count and the
// time remaining in the window. The throttled package comes with some stores
// in the throttled/store package. Custom stores can be created too, by implementing
// the Store interface.
//
// Requests that bust the rate limit are denied access and go through the denied handler,
// which may be specified on the Throttler and that defaults to the package-global
// variable DefaultDeniedHandler.
func RateLimit(q throttled.Quota, methods []string, vary *throttled.VaryBy, store throttled.Store) *throttled.Throttler {
// Extract requests and window
reqs, win := q.Quota()
// Create and return the throttler
return throttled.Custom(&rateLimiter{
reqs: reqs,
window: win,
vary: vary,
store: store,
methods: methods,
})
}
func main() {
flag.Parse()
var h http.Handler
var ok, ko int
var mu sync.Mutex
// Keep the start time to print since-time
start := time.Now()
// Create the custom throttler using our custom limiter
t := throttled.Custom(&customLimiter{})
// Set its denied handler
t.DeniedHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if *output == "v" || *output == "ko" {
log.Printf("KO: %s", time.Since(start))
}
throttled.DefaultDeniedHandler.ServeHTTP(w, r)
mu.Lock()
defer mu.Unlock()
ko++
})
// Throttle the OK handler
rand.Seed(time.Now().Unix())
h = t.Throttle(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if *output == "v" || *output == "ok" {
log.Printf("ok: %s", time.Since(start))
}
if *delayRes > 0 {
wait := time.Duration(rand.Intn(int(*delayRes)))
time.Sleep(wait)
}
w.WriteHeader(200)
mu.Lock()
defer mu.Unlock()
ok++
}))
// Print stats once in a while
go func() {
for _ = range time.Tick(10 * time.Second) {
mu.Lock()
log.Printf("ok: %d, ko: %d", ok, ko)
mu.Unlock()
}
}()
fmt.Println("server listening on port 9000")
http.ListenAndServe(":9000", h)
}