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package main
import (
"flag"
"fmt"
"log"
"math/rand"
"net/http"
"sync"
"time"
"gopkg.in/throttled/throttled.v1"
)
var (
delayRes = flag.Duration("delay-response", 0, "delay the response by a random duration between 0 and this value")
output = flag.String("output", "v", "type of output, one of `v`erbose, `q`uiet, `ok`-only, `ko`-only")
)
// Custom limiter: allow requests to the /a path on even seconds only, and
// allow access to the /b path on odd seconds only.
//
// Yes this is absurd. A more realistic case could be to allow requests to some
// contest page only during a limited time window.
type customLimiter struct {
}
func (c *customLimiter) Start() {
// No-op
}
func (c *customLimiter) Limit(w http.ResponseWriter, r *http.Request) (<-chan bool, error) {
s := time.Now().Second()
ch := make(chan bool, 1)
ok := (r.URL.Path == "/a" && s%2 == 0) || (r.URL.Path == "/b" && s%2 != 0)
ch <- ok
if *output == "v" {
log.Printf("Custom Limiter: Path=%s, Second=%d; ok? %v", r.URL.Path, s, ok)
}
return ch, nil
}
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)
}
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