🐛 Fix Mutability issue of UserContext in fiber.Ctx (#1522)

* existing tests clean up

* concurrent test for UserContext Reused

* comment on Ctx.userContext field

* userContext tests edited & fixed, userContext field removed, constant of userContextKey defined

ctx.go

@@ -34,6 +34,9 @@ const maxParams = 30
 
 const queryTag = "query"
 
+// userContextKey define the key name for storing context.Context in *fasthttp.RequestCtx
+const userContextKey = "__local_user_context__"
+
 // Ctx represents the Context which hold the HTTP request and response.
 // It has methods for the request query string, parameters, body, HTTP headers and so on.
 type Ctx struct {
@@ -53,7 +56,6 @@ type Ctx struct {
 	values              [maxParams]string    // Route parameter values
 	fasthttp            *fasthttp.RequestCtx // Reference to *fasthttp.RequestCtx
 	matched             bool                 // Non use route matched
-	userContext         context.Context
 }
 
 // Range data for c.Range
@@ -342,15 +344,18 @@ func (c *Ctx) Context() *fasthttp.RequestCtx {
 // UserContext returns a context implementation that was set by
 // user earlier or returns a non-nil, empty context,if it was not set earlier.
 func (c *Ctx) UserContext() context.Context {
-	if c.userContext == nil {
-		c.userContext = context.Background()
+	ctx, ok := c.fasthttp.UserValue(userContextKey).(context.Context)
+	if !ok {
+		ctx = context.Background()
+		c.SetUserContext(ctx)
 	}
-	return c.userContext
+
+	return ctx
 }
 
 // SetUserContext sets a context implementation by user.
 func (c *Ctx) SetUserContext(ctx context.Context) {
-	c.userContext = ctx
+	c.fasthttp.SetUserValue(userContextKey, ctx)
 }
 
 // Cookie sets a cookie by passing a cookie struct.

ctx_test.go

@@ -358,21 +358,21 @@ func Test_Ctx_BodyParser(t *testing.T) {
 		Name string `json:"name" xml:"name" form:"name" query:"name"`
 	}
 
-	 {
-		 var gzipJSON bytes.Buffer
-		 w := gzip.NewWriter(&gzipJSON)
-		 _, _ = w.Write([]byte(`{"name":"john"}`))
-		 _ = w.Close()
+	{
+		var gzipJSON bytes.Buffer
+		w := gzip.NewWriter(&gzipJSON)
+		_, _ = w.Write([]byte(`{"name":"john"}`))
+		_ = w.Close()
 
-		 c.Request().Header.SetContentType(MIMEApplicationJSON)
-		 c.Request().Header.Set(HeaderContentEncoding, "gzip")
-		 c.Request().SetBody(gzipJSON.Bytes())
-		 c.Request().Header.SetContentLength(len(gzipJSON.Bytes()))
-		 d := new(Demo)
-		 utils.AssertEqual(t, nil, c.BodyParser(d))
-		 utils.AssertEqual(t, "john", d.Name)
-		 c.Request().Header.Del(HeaderContentEncoding)
-	 }
+		c.Request().Header.SetContentType(MIMEApplicationJSON)
+		c.Request().Header.Set(HeaderContentEncoding, "gzip")
+		c.Request().SetBody(gzipJSON.Bytes())
+		c.Request().Header.SetContentLength(len(gzipJSON.Bytes()))
+		d := new(Demo)
+		utils.AssertEqual(t, nil, c.BodyParser(d))
+		utils.AssertEqual(t, "john", d.Name)
+		c.Request().Header.Del(HeaderContentEncoding)
+	}
 
 	testDecodeParser := func(contentType, body string) {
 		c.Request().Header.SetContentType(contentType)
@@ -508,7 +508,10 @@ func Test_Ctx_Context(t *testing.T) {
 
 // go test -run Test_Ctx_UserContext
 func Test_Ctx_UserContext(t *testing.T) {
-	c := Ctx{}
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
+
 	t.Run("Nil_Context", func(t *testing.T) {
 		ctx := c.UserContext()
 		utils.AssertEqual(t, ctx, context.Background())
@@ -518,16 +521,56 @@ func Test_Ctx_UserContext(t *testing.T) {
 		testKey := "Test Key"
 		testValue := "Test Value"
 		ctx := context.WithValue(context.Background(), testKey, testValue)
-		utils.AssertEqual(t, ctx.Value(testKey), testValue)
+		utils.AssertEqual(t, testValue, ctx.Value(testKey))
 	})
-
 }
 
-// go test -run Test_Ctx_UserContext
+// go test -run Test_Ctx_SetUserContext
 func Test_Ctx_SetUserContext(t *testing.T) {
-	c := Ctx{}
-	c.SetUserContext(context.Background())
-	utils.AssertEqual(t, c.UserContext(), context.Background())
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
+
+	testKey := "Test Key"
+	testValue := "Test Value"
+	ctx := context.WithValue(context.Background(), testKey, testValue)
+	c.SetUserContext(ctx)
+	utils.AssertEqual(t, testValue, c.UserContext().Value(testKey))
+}
+
+// go test -run Test_Ctx_UserContext_Multiple_Requests
+func Test_Ctx_UserContext_Multiple_Requests(t *testing.T) {
+	testKey := "foobar-key"
+	testValue := "foobar-value"
+
+	app := New()
+	app.Get("/", func(c *Ctx) error {
+		ctx := c.UserContext()
+
+		if ctx.Value(testKey) != nil {
+			return c.SendStatus(StatusInternalServerError)
+		}
+
+		input := utils.CopyString(c.Query("input", "NO_VALUE"))
+		ctx = context.WithValue(ctx, testKey, fmt.Sprintf("%s_%s", testValue, input))
+		c.SetUserContext(ctx)
+
+		return c.Status(StatusOK).SendString(fmt.Sprintf("resp_%s_returned", input))
+	})
+
+	// Consecutive Requests
+	for i := 1; i <= 10; i++ {
+		t.Run(fmt.Sprintf("request_%d", i), func(t *testing.T) {
+			resp, err := app.Test(httptest.NewRequest(MethodGet, fmt.Sprintf("/?input=%d", i), nil))
+
+			utils.AssertEqual(t, nil, err, "Unexpected error from response")
+			utils.AssertEqual(t, StatusOK, resp.StatusCode, "context.Context returned from c.UserContext() is reused")
+
+			b, err := ioutil.ReadAll(resp.Body)
+			utils.AssertEqual(t, nil, err, "Unexpected error from reading response body")
+			utils.AssertEqual(t, fmt.Sprintf("resp_%d_returned", i), string(b), "response text incorrect")
+		})
+	}
 }
 
 // go test -run Test_Ctx_Cookie