accesslog: NEW log broker and many more features

some fixes about context clone, fix response recorder concurrent access, fix reload views with only ParseTemplate and more

_examples/logging/request-logger/accesslog-broker/main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/middleware/accesslog"
+)
+
+func main() {
+	/*
+		On this example we will make use of the logs broker.
+		A handler will listen for any incoming logs and render
+		those logs as chunks of JSON to the client (e.g. browser) at real-time.
+		Note that this ^ can be done with Server-Sent Events but for the
+		sake of the example we'll do it using Transfer-Encoding: chunked.
+	*/
+
+	ac := accesslog.File("./access.log")
+	ac.TimeFormat = "2006-01-02 15:04:05"
+	ac.Async = true
+	broker := ac.Broker() // <- IMPORTANT
+
+	app := iris.New()
+	app.UseRouter(ac.Handler)
+
+	app.Get("/", indexHandler)
+	app.Get("/profile/{username}", profileHandler)
+	app.Post("/read_body", readBodyHandler)
+	app.Get("/logs", logsHandler(broker))
+
+	// http://localhost:8080/logs to see the logs at real-time.
+	app.Listen(":8080")
+}
+
+func indexHandler(ctx iris.Context) {
+	ctx.HTML("<h1>Index</h1>")
+}
+
+func profileHandler(ctx iris.Context) {
+	username := ctx.Params().Get("username")
+	ctx.HTML("Hello, <strong>%s</strong>!", username)
+}
+
+func readBodyHandler(ctx iris.Context) {
+	var request interface{}
+	if err := ctx.ReadBody(&request); err != nil {
+		ctx.StopWithPlainError(iris.StatusBadRequest, err)
+		return
+	}
+
+	ctx.JSON(iris.Map{"message": "OK", "data": request})
+}
+
+func logsHandler(b *accesslog.Broker) iris.Handler {
+	return func(ctx iris.Context) {
+		accesslog.Skip(ctx) // skip logging this handler, optionally.
+
+		logs := b.NewListener() // <- IMPORTANT
+
+		ctx.Header("Transfer-Encoding", "chunked")
+		notifyClose := ctx.Request().Context().Done()
+		for {
+			select {
+			case <-notifyClose:
+				b.CloseListener(logs) // <- IMPORTANT
+
+				err := ctx.Request().Context().Err()
+				ctx.Application().Logger().Infof("Listener closed [%v], loop end.", err)
+				return
+			case log := <-logs: // <- IMPORTANT
+				ctx.JSON(log, iris.JSON{Indent: "  ", UnescapeHTML: true})
+				ctx.ResponseWriter().Flush()
+			}
+		}
+	}
+}