Cache middleware now records the response and writes that to the DB

cache.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"net/http"
+	"net/http/httptest"
 	"net/url"
 	"time"
 )
@@ -10,18 +12,36 @@ import (
 func CacheMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		requestUrl, _ := url.ParseRequestURI(r.RequestURI)
+		path := SlashTrimmedPath(r)
 		if appConfig.cache.enable &&
 			// Check bypass query
 			!(requestUrl != nil && requestUrl.Query().Get("cache") == "0") {
-			mime, t, cache := getCache(SlashTrimmedPath(r), r.Context())
+			cacheTime, header, body := getCache(path, r.Context())
-			if cache == nil {
+			if cacheTime == 0 {
-				next.ServeHTTP(w, r)
+				recorder := httptest.NewRecorder()
+				next.ServeHTTP(recorder, r)
+				// Copy values from recorder
+				code := recorder.Code
+				// Send response
+				for k, v := range recorder.Header() {
+					w.Header()[k] = v
+				}
+				w.Header().Set("GoBlog-Cache", "MISS")
+				w.WriteHeader(code)
+				_, _ = w.Write(recorder.Body.Bytes())
+				// Save cache
+				if code == http.StatusOK {
+					saveCache(path, recorder.Header(), recorder.Body.Bytes())
+				}
 				return
 			} else {
-				expiresTime := time.Unix(t+appConfig.cache.expiration, 0).Format(time.RFC1123)
+				expiresTime := time.Unix(cacheTime+appConfig.cache.expiration, 0).Format(time.RFC1123)
+				for k, v := range header {
+					w.Header()[k] = v
+				}
 				w.Header().Set("Expires", expiresTime)
-				w.Header().Set("Content-Type", mime)
+				w.Header().Set("GoBlog-Cache", "HIT")
-				_, _ = w.Write(cache)
+				_, _ = w.Write(body)
 			}
 		} else {
 			next.ServeHTTP(w, r)
@@ -29,25 +49,26 @@ func CacheMiddleware(next http.Handler) http.Handler {
 	})
 }
 
-func getCache(path string, context context.Context) (string, int64, []byte) {
+func getCache(path string, context context.Context) (creationTime int64, header map[string][]string, body []byte) {
-	var mime string
+	var headerBytes []byte
-	var t int64
-	var cache []byte
 	allowedTime := time.Now().Unix() - appConfig.cache.expiration
-	row := appDb.QueryRowContext(context, "select COALESCE(mime, ''), COALESCE(time, 0), value from cache where path=? and time>=?", path, allowedTime)
+	row := appDb.QueryRowContext(context, "select COALESCE(time, 0), header, body from cache where path=? and time>=?", path, allowedTime)
-	_ = row.Scan(&mime, &t, &cache)
+	_ = row.Scan(&creationTime, &headerBytes, &body)
-	return mime, t, cache
+	header = make(map[string][]string)
+	_ = json.Unmarshal(headerBytes, &header)
+	return
 }
 
-func saveCache(path string, mime string, value []byte) {
+func saveCache(path string, header map[string][]string, body []byte) {
 	now := time.Now().Unix()
+	headerBytes, _ := json.Marshal(header)
 	startWritingToDb()
 	tx, err := appDb.Begin()
 	if err != nil {
 		return
 	}
 	_, _ = tx.Exec("delete from cache where time<?;", now-appConfig.cache.expiration)
-	_, _ = tx.Exec("insert or replace into cache (path, time, mime, value) values (?, ?, ?, ?);", path, now, mime, value)
+	_, _ = tx.Exec("insert or replace into cache (path, time, header, body) values (?, ?, ?, ?);", path, now, headerBytes, body)
 	_ = tx.Commit()
 	finishWritingToDb()
 }

database_migrations.go

@@ -34,7 +34,7 @@ func migrateDb() error {
 			&migrator.Migration{
 				Name: "00004",
 				Func: func(tx *sql.Tx) error {
-					_, err := tx.Exec("create table cache (path text not null primary key, time integer, mime text, value blob);")
+					_, err := tx.Exec("create table cache (path text not null primary key, time integer, header blob, body blob);")
 					return err
 				},
 			},

posts.go

@@ -32,11 +32,7 @@ func servePost(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	mime := "text/html"
+	w.Header().Set("Content-Type", "text/html")
-	if appConfig.cache.enable {
-		saveCache(path, mime, htmlContent)
-	}
-	w.Header().Set("Content-Type", mime)
 	_, _ = w.Write(htmlContent)
 }