From f38dcfba3b5a6298da23327ef3fc903a1648d590 Mon Sep 17 00:00:00 2001
From: Nazar Kanaev <nkanaev@live.com>
Date: Thu, 27 May 2021 13:16:03 +0100
Subject: [PATCH] cache feed icons

---
 src/server/routes.go      | 50 ++++++++++++++++++++++++++++++++-------
 src/server/routes_test.go | 41 ++++++++++++++++++++++++++++++++
 src/server/server.go      |  2 ++
 3 files changed, 85 insertions(+), 8 deletions(-)

diff --git a/src/server/routes.go b/src/server/routes.go
index a55a8b3..4529dc6 100644
--- a/src/server/routes.go
+++ b/src/server/routes.go
@@ -1,12 +1,15 @@
 package server
 
 import (
+	"crypto/md5"
 	"encoding/json"
+	"fmt"
 	"log"
 	"math"
 	"net/http"
 	"path/filepath"
 	"reflect"
+	"strconv"
 	"strings"
 
 	"github.com/nkanaev/yarr/src/assets"
@@ -143,20 +146,51 @@ func (s *Server) handleFeedErrors(c *router.Context) {
 	c.JSON(http.StatusOK, errors)
 }
 
+type feedicon struct {
+	ctype string
+	bytes []byte
+	etag  string
+}
+
 func (s *Server) handleFeedIcon(c *router.Context) {
-	// TODO: caching
 	id, err := c.VarInt64("id")
 	if err != nil {
 		c.Out.WriteHeader(http.StatusBadRequest)
 		return
 	}
-	feed := s.db.GetFeed(id)
-	if feed != nil && feed.Icon != nil {
-		c.Out.Header().Set("Content-Type", http.DetectContentType(*feed.Icon))
-		c.Out.Write(*feed.Icon)
-	} else {
-		c.Out.WriteHeader(http.StatusNotFound)
+
+	cachekey := "icon:" + strconv.FormatInt(id, 10)
+	cachedat := s.cache[cachekey]
+	if cachedat == nil {
+		feed := s.db.GetFeed(id)
+		if feed == nil || feed.Icon == nil {
+			c.Out.WriteHeader(http.StatusNotFound)
+			return
+		}
+
+		hash := md5.New()
+		hash.Write(*feed.Icon)
+
+		etag := fmt.Sprintf("%x", hash.Sum(nil))[:16]
+
+		cachedat = feedicon{
+			ctype: http.DetectContentType(*feed.Icon),
+			bytes: *(*feed).Icon,
+			etag:  etag,
+		}
+		s.cache[cachekey] = cachedat
 	}
+
+	icon := cachedat.(feedicon)
+
+	if c.Req.Header.Get("If-None-Match") == icon.etag {
+		c.Out.WriteHeader(http.StatusNotModified)
+		return
+	}
+
+	c.Out.Header().Set("Content-Type", icon.ctype)
+	c.Out.Header().Set("Etag", icon.etag)
+	c.Out.Write(icon.bytes)
 }
 
 func (s *Server) handleFeedList(c *router.Context) {
@@ -191,7 +225,7 @@ func (s *Server) handleFeedList(c *router.Context) {
 
 			c.JSON(http.StatusOK, map[string]interface{}{
 				"status": "success",
-				"feed": feed,
+				"feed":   feed,
 			})
 		default:
 			c.JSON(http.StatusOK, map[string]string{"status": "notfound"})
diff --git a/src/server/routes_test.go b/src/server/routes_test.go
index 053d2d7..cb53bb7 100644
--- a/src/server/routes_test.go
+++ b/src/server/routes_test.go
@@ -1,10 +1,13 @@
 package server
 
 import (
+	"fmt"
 	"io"
 	"log"
+	"net/http"
 	"net/http/httptest"
 	"os"
+	"reflect"
 	"testing"
 
 	"github.com/nkanaev/yarr/src/storage"
@@ -71,3 +74,41 @@ func TestIndexGzipped(t *testing.T) {
 		t.Errorf("invalid content-type header: %#v", response.Header.Get("content-type"))
 	}
 }
+
+func TestFeedIcons(t *testing.T) {
+	log.SetOutput(io.Discard)
+	db, _ := storage.New(":memory:")
+	icon := []byte("test")
+	feed := db.CreateFeed("", "", "", "", nil)
+	db.UpdateFeedIcon(feed.Id, &icon)
+	log.SetOutput(os.Stderr)
+
+	recorder := httptest.NewRecorder()
+	url := fmt.Sprintf("/api/feeds/%d/icon", feed.Id)
+	request := httptest.NewRequest("GET", url, nil)
+
+	handler := NewServer(db, "127.0.0.1:8000").handler()
+	handler.ServeHTTP(recorder, request)
+	response := recorder.Result()
+
+	if response.StatusCode != http.StatusOK {
+		t.Fatal()
+	}
+	body, _ := io.ReadAll(response.Body)
+	if !reflect.DeepEqual(body, icon) {
+		t.Fatal()
+	}
+	if response.Header.Get("Etag") == "" {
+		t.Fatal()
+	}
+
+	recorder2 := httptest.NewRecorder()
+	request2 := httptest.NewRequest("GET", url, nil)
+	request2.Header.Set("If-None-Match", response.Header.Get("Etag"))
+	handler.ServeHTTP(recorder2, request2)
+	response2 := recorder2.Result()
+
+	if response2.StatusCode != http.StatusNotModified {
+		t.Fatal("got", response2.StatusCode)
+	}
+}
diff --git a/src/server/server.go b/src/server/server.go
index 0946b01..7aeebac 100644
--- a/src/server/server.go
+++ b/src/server/server.go
@@ -12,6 +12,7 @@ type Server struct {
 	Addr   string
 	db     *storage.Storage
 	worker *worker.Worker
+	cache  map[string]interface{}
 
 	BasePath string
 
@@ -28,6 +29,7 @@ func NewServer(db *storage.Storage, addr string) *Server {
 		db:     db,
 		Addr:   addr,
 		worker: worker.NewWorker(db),
+		cache:  make(map[string]interface{}),
 	}
 }