mirror of https://github.com/jlelse/GoBlog
Implement basic db-based cache
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parent
6c4a9476b4
commit
7becbd6aad
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@ -0,0 +1,53 @@
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package main
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import (
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"context"
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"net/http"
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"net/url"
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"time"
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)
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func CacheMiddleware(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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requestUrl, _ := url.ParseRequestURI(r.RequestURI)
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if appConfig.cache.enable &&
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// Check bypass query
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!(requestUrl != nil && requestUrl.Query().Get("cache") == "0") {
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mime, t, cache := getCache(SlashTrimmedPath(r), r.Context())
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if cache == nil {
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next.ServeHTTP(w, r)
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return
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} else {
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expiresTime := time.Unix(t+appConfig.cache.expiration, 0).Format(time.RFC1123)
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w.Header().Set("Expires", expiresTime)
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w.Header().Set("Content-Type", mime)
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_, _ = w.Write(cache)
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}
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} else {
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next.ServeHTTP(w, r)
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}
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})
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}
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func getCache(path string, context context.Context) (string, int64, []byte) {
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var mime string
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var t int64
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var cache []byte
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allowedTime := time.Now().Unix() - appConfig.cache.expiration
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row := appDb.QueryRowContext(context, "select COALESCE(mime, ''), COALESCE(time, 0), value from cache where path=? and time>=?", path, allowedTime)
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_ = row.Scan(&mime, &t, &cache)
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return mime, t, cache
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}
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func saveCache(path string, mime string, value []byte) {
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now := time.Now().Unix()
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startWritingToDb()
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tx, err := appDb.Begin()
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if err != nil {
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return
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}
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_, _ = tx.Exec("delete from cache where time<?;", now-appConfig.cache.expiration)
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_, _ = tx.Exec("insert or replace into cache (path, time, mime, value) values (?, ?, ?, ?);", path, now, mime, value)
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_ = tx.Commit()
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finishWritingToDb()
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}
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16
config.go
16
config.go
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@ -8,6 +8,7 @@ import (
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type config struct {
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server *configServer
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db *configDb
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cache *configCache
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}
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type configServer struct {
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@ -19,9 +20,15 @@ type configDb struct {
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file string
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}
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type configCache struct {
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enable bool
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expiration int64
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}
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var appConfig = &config{
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server: &configServer{},
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db: &configDb{},
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cache: &configCache{},
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}
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func initConfig() error {
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@ -45,6 +52,15 @@ func initConfig() error {
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viper.SetDefault(databaseFile, "data/db.sqlite")
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appConfig.db.file = viper.GetString(databaseFile)
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logConfig(databaseFile, appConfig.db.file)
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// Caching
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cacheEnable := "cache.enable"
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viper.SetDefault(cacheEnable, true)
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appConfig.cache.enable = viper.GetBool(cacheEnable)
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logConfig(cacheEnable, appConfig.cache.enable)
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cacheExpiration := "cache.expiration"
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viper.SetDefault(cacheExpiration, 600)
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appConfig.cache.expiration = viper.GetInt64(cacheExpiration)
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logConfig(cacheExpiration, appConfig.cache.expiration)
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return nil
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}
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@ -31,6 +31,13 @@ func migrateDb() error {
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return err
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},
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},
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&migrator.Migration{
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Name: "00004",
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Func: func(tx *sql.Tx) error {
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_, err := tx.Exec("create table cache (path text not null primary key, time integer, mime text, value blob);")
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return err
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},
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},
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),
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)
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if err != nil {
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4
http.go
4
http.go
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@ -63,7 +63,7 @@ func buildHandler() (http.Handler, error) {
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} else {
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for _, path := range allPostPaths {
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if path != "" {
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r.Get(path, servePost)
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r.With(CacheMiddleware).Get(path, servePost)
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}
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}
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}
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@ -109,4 +109,4 @@ func SlashTrimmedPath(r *http.Request) string {
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path = strings.TrimSuffix(path, "/")
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}
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return path
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}
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}
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9
posts.go
9
posts.go
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@ -18,7 +18,8 @@ type post struct {
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}
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func servePost(w http.ResponseWriter, r *http.Request) {
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post, err := getPost(SlashTrimmedPath(r), r.Context())
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path := SlashTrimmedPath(r)
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post, err := getPost(path, r.Context())
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if err == postNotFound {
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http.NotFound(w, r)
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return
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@ -31,7 +32,11 @@ func servePost(w http.ResponseWriter, r *http.Request) {
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http.Error(w, err.Error(), http.StatusInternalServerError)
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return
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}
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w.Header().Set("Content-Type", "text/html")
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mime := "text/html"
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if appConfig.cache.enable {
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saveCache(path, mime, htmlContent)
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}
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w.Header().Set("Content-Type", mime)
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_, _ = w.Write(htmlContent)
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}
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