mirror of https://github.com/jlelse/GoBlog
54 lines
1.5 KiB
Go
54 lines
1.5 KiB
Go
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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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