write about caching

config/caching.go

@@ -0,0 +1,6 @@
+package config
+
+import "time"
+
+// todo: make this configurable
+const ExpiresIn = 5 * time.Minute

doc/dev/framework-migration.md

@@ -14,3 +14,25 @@
 
 - add limiter (maybe it should be in nginx)
 - add caching (maybe it should be in nginx)
+
+## Guide for caching
+
+The majority of the site's traffic is images, and all images on the Pixiv route can be cached forever.
+  Cached in browser: pixiv headers cache images for year
+  On the server, the reverse proxy (e.g. nginx) can be cached worry-free forever.
+
+JSON requests to Pixiv can be cached for some time.
+  todo: We should have a middleware handling that. 
+
+Assets are already cached properly thanks to net/http.
+
+Every rendered page can be cached for 5 minutes or so in the browser.
+However, after changing settings, the page need to be refreshed instantly.
+  Cache in browser: todo: read below implement in template/render.go
+  The reverse proxy shouldn't do anything about this.
+
+The only three headers that controls caching in browser and middleboxes:
+
+- [Age](https://httpwg.org/specs/rfc9111.html#field.age)
+- [Cache-Control](https://httpwg.org/specs/rfc9111.html#field.cache-control)
+- [Expires](https://httpwg.org/specs/rfc9111.html#field.expires)

main.go

@@ -35,7 +35,10 @@ func CanRequestSkipLimiter(r *http.Request) bool {
 func CanRequestSkipLogger(r *http.Request) bool {
 	// return false
 	path := r.URL.Path
-	return CanRequestSkipLimiter(r) ||
+	return strings.HasPrefix(path, "/img/") ||
+		strings.HasPrefix(path, "/css/") ||
+		strings.HasPrefix(path, "/js/") ||
+		strings.HasPrefix(path, "/proxy/s.pximg.net/") ||
 		strings.HasPrefix(path, "/proxy/i.pximg.net/")
 }
 
@@ -82,7 +85,6 @@ func main() {
 			router.ServeHTTP(w, r)
 		}
 
-
 		CatchError(func(w http.ResponseWriter, r *http.Request) error {
 			err := GetUserContext(r).err
 			if err != nil { // error handler
@@ -228,7 +230,7 @@ func defineRoutes() *mux.Router {
 
 	// Legacy illust URL
 	router.HandleFunc("/member_illust.php", func(w http.ResponseWriter, r *http.Request) {
-		http.Redirect(w, r, "/artworks/"+ routes.GetQueryParam(r, "illust_id"), http.StatusPermanentRedirect)
+		http.Redirect(w, r, "/artworks/"+routes.GetQueryParam(r, "illust_id"), http.StatusPermanentRedirect)
 	}).Methods("GET")
 
 	router.NewRoute().HandlerFunc(CatchError(func(w http.ResponseWriter, r *http.Request) error {

template/render.go

@@ -6,7 +6,9 @@ import (
 	"net/http"
 	"reflect"
 	"strings"
+	// "time"
 
+	// "codeberg.org/vnpower/pixivfe/v2/config"
 	"codeberg.org/vnpower/pixivfe/v2/session"
 	"codeberg.org/vnpower/pixivfe/v2/utils"
 
@@ -35,6 +37,8 @@ func InitTemplatingEngine(DisableCache bool) {
 // render the template selected based on the name of type `T`
 func Render[T any](w http.ResponseWriter, r *http.Request, data T) error {
 	w.Header().Set("content-type", "text/html; charset=utf-8")
+	// todo: think about caching a bit more
+	// w.Header().Set("expires", time.Now().Add(config.ExpiresIn).Format(time.RFC1123))
 	return RenderInner(w, GetTemplatingVariables(r), data)
 }