🐛 Fix expiration time in cache middleware

[breakbuidl]

Even if ExpirationGenerator was provided in cache config, Expiration was used anyway.

fixes #1869

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[breakbuidl]

Could any of the maintainers please approve running workflows?

[ReneWerner87]

please reduce the time for this, otherwise the test procedure will be greatly extended

you can also wait nanoseconds, micro or milliseconds, whichever is stable

if necessary i would decide for a few milliseconds, because the process also takes a bit of time

[breakbuidl]

Some very strange functioning from code.

I set expiration time to time.Millisecond * time.Duration(newCacheTime). And, when time > 1 sec i.e newCacheTime >= 1000 everything works fine. But, if newCacheTime < 1000 it seems that the response is not cached at all.

   app.Use(New(Config{ExpirationGenerator: func(c *fiber.Ctx, cfg *Config) time.Duration {
   	called = true
   	newCacheTime, _ = strconv.Atoi(c.GetRespHeader("Cache-Time", "600"))
   	return time.Millisecond * time.Duration(newCacheTime)
   }}))

   app.Get("/", func(c *fiber.Ctx) error {
   	c.Response().Header.Add("Cache-Time", "500")
   	now := fmt.Sprintf("%d", time.Now().UnixNano())
   	return c.SendString(now)
   })

   resp, err := app.Test(httptest.NewRequest("GET", "/", nil))
   utils.AssertEqual(t, nil, err)
   utils.AssertEqual(t, true, called)
   utils.AssertEqual(t, 500, newCacheTime)

   // Sleep until the cache is expired
   // time.Sleep(700 * time.Millisecond)

   cachedResp, err := app.Test(httptest.NewRequest("GET", "/", nil))
   utils.AssertEqual(t, nil, err)

   body, err := ioutil.ReadAll(resp.Body)
   utils.AssertEqual(t, nil, err)
   cachedBody, err := ioutil.ReadAll(cachedResp.Body)
   utils.AssertEqual(t, nil, err)

   if !bytes.Equal(body, cachedBody) {
   	t.Errorf("Cache should not have expired: %s, %s", body, cachedBody)
   }

The above test fails with the message - Cache should not have expired: 1651076560555101139, 1651076560555237907

[breakbuidl]

I tried setting newCacheTime to 999 and it failed.

[breakbuidl]

Also, I don't know if it's related or not. But, I played around with Test_CacheExpired and when Expiration is set to less than 1 Second, somehow the expiration time is 1 Minute

The below test fails.

t.Parallel()

	app := fiber.New()
	app.Use(New(Config{Expiration: 500 * time.Millisecond}))

	app.Get("/", func(c *fiber.Ctx) error {
		return c.SendString(fmt.Sprintf("%d", time.Now().UnixNano()))
	})

	resp, err := app.Test(httptest.NewRequest("GET", "/", nil))
	utils.AssertEqual(t, nil, err)
	body, err := ioutil.ReadAll(resp.Body)
	utils.AssertEqual(t, nil, err)

	// Sleep until the cache is expired
	time.Sleep(1000 * time.Millisecond)

	respCached, err := app.Test(httptest.NewRequest("GET", "/", nil))
	utils.AssertEqual(t, nil, err)
	bodyCached, err := ioutil.ReadAll(respCached.Body)
	utils.AssertEqual(t, nil, err)

	if bytes.Equal(body, bodyCached) {
		t.Errorf("Cache should have expired: %s, %s", body, bodyCached)
	}

However, if I change the sleep time to more than 60 seconds say 61000 * time.Millisecond, it passes.

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