Update caching logic/headers (#184)

* Improve caching by adding etags and reducing the max-age

* Move caching into middleware. Set cache headers on segments

router/middleware/caching.go

@@ -0,0 +1,64 @@
+package middleware
+
+import (
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+
+	"github.com/amalfra/etag"
+)
+
+//DisableCache writes the disable cache header on the responses
+func DisableCache(w http.ResponseWriter) {
+	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
+	w.Header().Set("Expires", "Thu, 1 Jan 1970 00:00:00 GMT")
+}
+
+func setCacheSeconds(seconds int, w http.ResponseWriter) {
+	secondsStr := strconv.Itoa(seconds)
+	w.Header().Set("Cache-Control", "public, max-age="+secondsStr)
+}
+
+// ProcessEtags gets and sets ETags for caching purposes
+func ProcessEtags(w http.ResponseWriter, r *http.Request) int {
+	info, err := os.Stat(filepath.Join("webroot", r.URL.Path))
+	if err != nil {
+		return 0
+	}
+
+	localContentEtag := etag.Generate(info.ModTime().String(), true)
+	if remoteEtagHeader := r.Header.Get("If-None-Match"); remoteEtagHeader != "" {
+		if remoteEtagHeader == localContentEtag {
+			return http.StatusNotModified
+		}
+	}
+
+	w.Header().Set("Etag", localContentEtag)
+
+	return 0
+}
+
+// SetCachingHeaders will set the cache control header of a response
+func SetCachingHeaders(w http.ResponseWriter, r *http.Request) {
+	setCacheSeconds(getCacheDurationSecondsForPath(r.URL.Path), w)
+}
+
+func getCacheDurationSecondsForPath(filePath string) int {
+	if path.Base(filePath) == "thumbnail.jpg" {
+		// Thumbnails re-generate during live
+		return 20
+	} else if path.Ext(filePath) == ".js" || path.Ext(filePath) == ".css" {
+		// Cache javascript & CSS
+		return 60
+	} else if path.Ext(filePath) == ".ts" {
+		// Cache video segments as long as you want. They can't change.
+		// This matters most for local hosting of segments for recordings
+		// and not for live or 3rd party storage.
+		return 31557600
+	}
+
+	// Default cache length in seconds
+	return 30 * 60
+}

router/middleware/disableCache.go

@@ -1,19 +0,0 @@
-package middleware
-
-import (
-	"net/http"
-	"strconv"
-)
-
-//DisableCache writes the disable cache header on the responses
-func DisableCache(w http.ResponseWriter) {
-	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
-	w.Header().Set("Expires", "0")
-}
-
-//SetCache will set the cache control header of a response
-func SetCache(days int, w http.ResponseWriter) {
-	seconds := strconv.Itoa(days * 86400)
-	w.Header().Set("Cache-Control", "max-age="+seconds)
-	w.Header().Set("Expires", seconds)
-}