add Context.SendFileWithRate, ServeFileWithRate and ServeContentWithRate

as requested at: https://github.com/kataras/iris/issues/1493


Former-commit-id: 7783fde04b4247056e6309e7ec1df27f027dc655

_examples/file-server/send-files/main.go

@@ -6,11 +6,26 @@ import (
 
 func main() {
 	app := iris.New()
+	app.Logger().SetLevel("debug")
 
-	app.Get("/", func(ctx iris.Context) {
-		file := "./files/first.zip"
-		ctx.SendFile(file, "c.zip")
-	})
+	app.Get("/", download)
+	app.Get("/download", downloadWithRateLimit)
 
 	app.Listen(":8080")
 }
+
+func download(ctx iris.Context) {
+	src := "./files/first.zip"
+	ctx.SendFile(src, "client.zip")
+}
+
+func downloadWithRateLimit(ctx iris.Context) {
+	// REPLACE THAT WITH A BIG LOCAL FILE OF YOUR OWN.
+	src := "./files/first.zip"
+	dest := "" /* optionally, keep it empty to resolve the filename based on the "src" */
+
+	// Limit download speed to ~50Kb/s with a burst of 100KB.
+	limit := 50.0 * iris.KB
+	burst := 100 * iris.KB
+	ctx.SendFileWithRate(src, dest, limit, burst)
+}