badconnection.go

package app

import (
	"math/rand"
	"time"

	"github.com/revel/revel"
)

// randomDuration generates a duration between min and max duration.
func randomDuration(min, max time.Duration) time.Duration {
	if max <= min {
		revel.ERROR.Printf("randomDuration: Duration %v is not bigger than %v", max, min)
		return min
	}
	r := rand.Int63n(int64(max)-int64(min)) + int64(min)
	return time.Duration(r)
}

// BadConnectionFilter will add random delays return empty replies and even hang the connections
//
// Use "badconnection.enable" in revel configuration to enable the filter when it is inserted into
// the filter chain.
//
// Additional options are:
//  - "badconnection.longdelay.percent": Percent chance you will get a random 1.5 to 20 second delay. Default: 25.
//  - "badconnection.noreply.percent": Percent chance you will get an empty reply. Default: 15.
//  - "badconnection.hang.percent": Percent chance you will get a hung connection (never returning a reply). Default: 5.
func BadConnectionFilter(c *revel.Controller, fc []revel.Filter) {
	if revel.Config.BoolDefault("badconnection.enable", false) {
		a := revel.Config.IntDefault("badconnection.base.min", 36)
		b := revel.Config.IntDefault("badconnection.base.max", 150)
		dur := randomDuration(time.Millisecond*time.Duration(a), time.Millisecond*time.Duration(b))

		time.Sleep(dur)

		// Long delay
		r := rand.Uint32() % 100 // Gives 0 to 99 ( we only stall half the delay)
		if r < uint32(revel.Config.IntDefault("badconnection.longdelay.percent", 25)) {
			a = revel.Config.IntDefault("badconnection.longdelay.min", 1500) / 2
			b = revel.Config.IntDefault("badconnection.longdelay.max", 15000) / 2
			dur = randomDuration(time.Millisecond*time.Duration(a), time.Millisecond*time.Duration(b))
			revel.TRACE.Printf("Sleeping for additional %s on %s\n", dur, c.Request.RequestURI)
			time.Sleep(dur)
		}

		// Empty reply
		r = rand.Uint32() % 200 // Gives 0 to 199
		if r < uint32(revel.Config.IntDefault("badconnection.noreply.percent", 15)) {
			revel.TRACE.Printf("Returning no response on %s, because\n", c.Request.RequestURI)
			return
		}

		//Hung connection
		r = rand.Uint32() % 200 // Gives 0 to 199
		if r < uint32(revel.Config.IntDefault("badconnection.hang.percent", 5)) {
			revel.TRACE.Printf("Hanging on %s\n", c.Request.RequestURI)
			time.Sleep(time.Hour * 5000)
		}
	}
	// Call next in filter chain
	fc[0](c, fc[1:])

	if revel.Config.BoolDefault("badconnection.enable", false) {
		time.Sleep(randomDuration(time.Millisecond*36, time.Millisecond*150))

		// Long delay
		r := rand.Uint32() % 100 // Gives 0 to 99 ( we only stall half the delay)
		if r < uint32(revel.Config.IntDefault("badconnection.longdelay.percent", 25)) {
			a := revel.Config.IntDefault("badconnection.longdelay.min", 1500) / 2
			b := revel.Config.IntDefault("badconnection.longdelay.max", 15000) / 2
			dur := randomDuration(time.Millisecond*time.Duration(a), time.Millisecond*time.Duration(b))
			revel.TRACE.Printf("Sleeping for additional %s on %s\n", dur, c.Request.RequestURI)
			time.Sleep(dur)
		}

		// Empty reply
		r = rand.Uint32() % 200 // Gives 0 to 199
		if r < uint32(revel.Config.IntDefault("badconnection.noreply.percent", 15)) {
			revel.TRACE.Printf("Returning no response on %s, because\n", c.Request.RequestURI)
			return
		}

		//Hung connection
		r = rand.Uint32() % 200 // Gives 0 to 199
		if r < uint32(revel.Config.IntDefault("badconnection.hang.percent", 5)) {
			revel.TRACE.Printf("Hanging on %s\n", c.Request.RequestURI)
			time.Sleep(time.Hour * 5000)
		}
	}
}