Add cache header

For now we only add it to images/js/css and not for html/json/xml
generated pages.

config.go

@@ -26,6 +26,7 @@ const (
 	NEW_ITEMS_PAGE            = 50
 	NUM_NEWS                  = 10
 	DAYS_NEWS_INDEXPAGE       = 15
+	CACHE_MAX_AGE             = 1800
 
 	STORE_PATH       = "store/"
 	TEMPLATE_PATH    = "templates/"

stats.go

@@ -53,6 +53,7 @@ func (sg StatsGatherer) Gather(function func(handler)) func(http.ResponseWriter,
 		h.w = w
 		h.r = r
 		h.sess = GetSession(r, h.db)
+
 		function(h)
 
 		sg.channel <- statsRequest{time.Now(), mux.Vars(r), h.sess, r}

trantor.go

@@ -3,6 +3,7 @@ package main
 import (
 	log "github.com/cihub/seelog"
 
+	"fmt"
 	"io"
 	"net/http"
 	"os"
@@ -220,11 +221,27 @@ func initRouter(db *database.DB, sg *StatsGatherer) {
 	r.HandleFunc("/news/edit", sg.Gather(editNewsHandler)).Methods("GET")
 	r.HandleFunc("/news/edit", sg.Gather(postNewsHandler)).Methods("POST")
 
-	h := http.FileServer(http.Dir(IMG_PATH))
-	r.Handle("/img/{img}", http.StripPrefix("/img/", h))
-	h = http.FileServer(http.Dir(CSS_PATH))
-	r.Handle("/css/{css}", http.StripPrefix("/css/", h))
-	h = http.FileServer(http.Dir(JS_PATH))
-	r.Handle("/js/{js}", http.StripPrefix("/js/", h))
+	r.HandleFunc("/img/{img}", fileServer(IMG_PATH, "/img/"))
+	r.HandleFunc("/css/{css}", fileServer(CSS_PATH, "/css/"))
+	r.HandleFunc("/js/{js}", fileServer(JS_PATH, "/js/"))
 	http.Handle("/", r)
 }
+
+func fileServer(path string, prefix string) func(w http.ResponseWriter, r *http.Request) {
+	// FIXME: is there a cleaner way without handler?
+	h := http.FileServer(http.Dir(path))
+	handler := http.StripPrefix(prefix, h)
+	return func(w http.ResponseWriter, r *http.Request) {
+		addCacheControlHeader(w, false)
+		handler.ServeHTTP(w, r)
+	}
+}
+
+func addCacheControlHeader(w http.ResponseWriter, private bool) {
+	// FIXME: cache of download and cover don't depends on user login
+	if private {
+		w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%d, private", CACHE_MAX_AGE))
+	} else {
+		w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%d, public", CACHE_MAX_AGE))
+	}
+}