some major improvements to the (server-side) cache middleware and an example of a client-side responsibility cache

Former-commit-id: 93d3a7a6f163c6d49f315f86d10e63f7b1b1d93a

cache/client/handler.go

@@ -4,7 +4,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/kataras/iris/cache/cfg"
 	"github.com/kataras/iris/cache/client/rule"
 	"github.com/kataras/iris/cache/entry"
 	"github.com/kataras/iris/context"
@@ -66,6 +65,12 @@ var emptyHandler = func(ctx context.Context) {
 	ctx.StopExecution()
 }
 
+func parseLifeChanger(ctx context.Context) entry.LifeChanger {
+	return func() time.Duration {
+		return time.Duration(ctx.MaxAge()) * time.Second
+	}
+}
+
 ///TODO: debug this and re-run the parallel tests on larger scale,
 // because I think we have a bug here when `core/router#StaticWeb` is used after this middleware.
 func (h *Handler) ServeHTTP(ctx context.Context) {
@@ -135,14 +140,19 @@ func (h *Handler) ServeHTTP(ctx context.Context) {
 		// no need to copy the body, its already done inside
 		body := recorder.Body()
 		if len(body) == 0 {
-			// if no body then just exit
+			// if no body then just exit.
 			return
 		}
 
 		// check for an expiration time if the
 		// given expiration was not valid then check for GetMaxAge &
 		// update the response & release the recorder
-		e.Reset(recorder.StatusCode(), recorder.Header().Get(cfg.ContentTypeHeader), body, GetMaxAge(ctx.Request()))
+		e.Reset(
+			recorder.StatusCode(),
+			recorder.Header(),
+			body,
+			parseLifeChanger(ctx),
+		)
 
 		// fmt.Printf("reset cache entry\n")
 		// fmt.Printf("key: %s\n", key)
@@ -152,12 +162,13 @@ func (h *Handler) ServeHTTP(ctx context.Context) {
 	}
 
 	// if it's valid then just write the cached results
-	ctx.ContentType(response.ContentType())
+	entry.CopyHeaders(ctx.ResponseWriter().Header(), response.Headers())
+	context.SetLastModified(ctx, e.LastModified)
 	ctx.StatusCode(response.StatusCode())
 	ctx.Write(response.Body())
 
 	// fmt.Printf("key: %s\n", key)
-	// fmt.Printf("write content type: %s\n", response.ContentType())
+	// fmt.Printf("write content type: %s\n", response.Headers()["ContentType"])
 	// fmt.Printf("write body len: %d\n", len(response.Body()))
 
 }