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GoBlog
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Massively improve cache using singleflight and storing cacheitems in memory

This commit is contained in:
Jan-Lukas Else 2020-10-19 23:02:57 +02:00
parent a2190306da
commit a3c6ba832e
5 changed files with 62 additions and 101 deletions
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149
cache.go
View File

@ -1,76 +1,36 @@
package main
import (
"database/sql"
"net/http"
"net/http/httptest"
"net/url"
"sync"
"time"
"golang.org/x/sync/singleflight"
)
var cacheMutexMapMutex *sync.Mutex
var cacheMutexes map[string]*sync.Mutex
var cacheDb *sql.DB
var cacheDbWriteMutex = &sync.Mutex{}
var cacheMap = map[string]*cacheItem{}
var cacheMutex = &sync.RWMutex{}
func initCache() (err error) {
cacheMutexMapMutex = &sync.Mutex{}
cacheMutexes = map[string]*sync.Mutex{}
cacheDb, err = sql.Open("sqlite3", ":memory:")
if err != nil {
return err
}
tx, err := cacheDb.Begin()
if err != nil {
return
}
_, err = tx.Exec("CREATE TABLE cache (path text not null primary key, time integer, header blob, body blob);")
if err != nil {
return
}
err = tx.Commit()
if err != nil {
return
}
return
}
func startWritingToCacheDb() {
cacheDbWriteMutex.Lock()
}
func finishWritingToCacheDb() {
cacheDbWriteMutex.Unlock()
}
var requestGroup singleflight.Group
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") {
// Check cache mutex
cacheMutexMapMutex.Lock()
if cacheMutexes[path] == nil {
cacheMutexes[path] = &sync.Mutex{}
}
cacheMutexMapMutex.Unlock()
// Get cache
cm := cacheMutexes[path]
cm.Lock()
cacheTime, header, body := getCache(path)
cm.Unlock()
if cacheTime == 0 {
cm.Lock()
// Render cache
renderCache(path, next, w, r)
cm.Unlock()
return
}
cacheTimeString := time.Unix(cacheTime, 0).Format(time.RFC1123)
expiresTimeString := time.Unix(cacheTime+appConfig.Cache.Expiration, 0).Format(time.RFC1123)
!(r.URL.Query().Get("cache") == "0") &&
// check method
(r.Method == http.MethodGet || r.Method == http.MethodHead) {
// Fix path
path := slashTrimmedPath(r)
// Get cache or render it
cacheInterface, _, _ := requestGroup.Do(path, func() (interface{}, error) {
return getCache(path, next, r), nil
})
cache := cacheInterface.(*cacheItem)
// log.Println(string(cache.body))
cacheTimeString := time.Unix(cache.creationTime, 0).Format(time.RFC1123)
expiresTimeString := time.Unix(cache.creationTime+appConfig.Cache.Expiration, 0).Format(time.RFC1123)
// check conditional request
ifModifiedSinceHeader := r.Header.Get("If-Modified-Since")
if ifModifiedSinceHeader != "" && ifModifiedSinceHeader == cacheTimeString {
@ -80,13 +40,14 @@ func cacheMiddleware(next http.Handler) http.Handler {
return
}
// copy cached headers
for k, v := range header {
for k, v := range cache.header {
w.Header()[k] = v
}
setCacheHeaders(w, cacheTimeString, expiresTimeString)
w.Header().Set("GoBlog-Cache", "HIT")
// set status code
w.WriteHeader(cache.code)
// write cached body
_, _ = w.Write(body)
_, _ = w.Write(cache.body)
return
}
next.ServeHTTP(w, r)
@ -100,46 +61,38 @@ func setCacheHeaders(w http.ResponseWriter, cacheTimeString string, expiresTimeS
w.Header().Set("Expires", expiresTimeString)
}
func renderCache(path string, next http.Handler, w http.ResponseWriter, r *http.Request) {
// No cache available
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
}
now := time.Now()
setCacheHeaders(w, now.Format(time.RFC1123), time.Unix(now.Unix()+appConfig.Cache.Expiration, 0).Format(time.RFC1123))
w.Header().Set("GoBlog-Cache", "MISS")
w.WriteHeader(code)
_, _ = w.Write(recorder.Body.Bytes())
// Save cache
if code == http.StatusOK {
saveCache(path, now, recorder.Header(), recorder.Body.Bytes())
}
type cacheItem struct {
creationTime int64
code int
header http.Header
body []byte
}
func getCache(path string) (creationTime int64, header map[string][]string, body []byte) {
var headerBytes []byte
allowedTime := time.Now().Unix() - appConfig.Cache.Expiration
row := cacheDb.QueryRow("select COALESCE(time, 0), header, body from cache where path=? and time>=?", path, allowedTime)
_ = row.Scan(&creationTime, &headerBytes, &body)
header = make(map[string][]string)
_ = json.Unmarshal(headerBytes, &header)
return
}
func saveCache(path string, now time.Time, header map[string][]string, body []byte) {
headerBytes, _ := json.Marshal(header)
startWritingToCacheDb()
defer finishWritingToCacheDb()
_, _ = cacheDb.Exec("insert or replace into cache (path, time, header, body) values (?, ?, ?, ?);", path, now.Unix(), headerBytes, body)
func getCache(path string, next http.Handler, r *http.Request) *cacheItem {
cacheMutex.RLock()
item, ok := cacheMap[path]
cacheMutex.RUnlock()
if !ok || item.creationTime < time.Now().Unix()-appConfig.Cache.Expiration {
item = &cacheItem{}
// No cache available
recorder := httptest.NewRecorder()
next.ServeHTTP(recorder, r)
// copy values from recorder
now := time.Now()
item.creationTime = now.Unix()
item.code = recorder.Code
item.header = recorder.Header()
item.body = recorder.Body.Bytes()
// Save cache
cacheMutex.Lock()
cacheMap[path] = item
cacheMutex.Unlock()
}
return item
}
func purgeCache() {
startWritingToCacheDb()
defer finishWritingToCacheDb()
_, _ = cacheDb.Exec("delete from cache; vacuum;")
cacheMutex.Lock()
cacheMap = map[string]*cacheItem{}
cacheMutex.Unlock()
}

1
go.mod
View File

@ -37,6 +37,7 @@ require (
github.com/yuin/goldmark-emoji v1.0.1
golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897
golang.org/x/net v0.0.0-20201016165138-7b1cca2348c0 // indirect
golang.org/x/sync v0.0.0-20201008141435-b3e1573b7520
golang.org/x/sys v0.0.0-20201018230417-eeed37f84f13 // indirect
gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b // indirect
gopkg.in/ini.v1 v1.62.0 // indirect

3
go.sum
View File

@ -352,7 +352,10 @@ golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJ
golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20201008141435-b3e1573b7520 h1:Bx6FllMpG4NWDOfhMBz1VR2QYNp/SAOHPIAsaVmxfPo=
golang.org/x/sync v0.0.0-20201008141435-b3e1573b7520/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sys v0.0.0-20180823144017-11551d06cbcc/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=

9
http.go
View File

@ -2,7 +2,9 @@ package main
import (
"compress/flate"
"log"
"net/http"
"os"
"strconv"
"strings"
"sync"
@ -73,7 +75,10 @@ func buildHandler() (http.Handler, error) {
r.Use(middleware.Recoverer)
if appConfig.Server.Logging {
r.Use(middleware.RealIP)
r.Use(middleware.Logger)
r.Use(middleware.RequestLogger(&middleware.DefaultLogFormatter{
Logger: log.New(os.Stdout, "", log.LstdFlags),
NoColor: true,
}))
}
r.Use(middleware.Compress(flate.DefaultCompression))
r.Use(middleware.StripSlashes)
@ -205,7 +210,7 @@ func buildHandler() (http.Handler, error) {
r.With(cacheMiddleware, minifier.Middleware).Get(sitemapPath, serveSitemap)
// Check redirects, then serve 404
r.With(checkRegexRedirects, minifier.Middleware).NotFound(serve404)
r.With(checkRegexRedirects, cacheMiddleware, minifier.Middleware).NotFound(serve404)
return r, nil
}

1
main.go
View File

@ -29,7 +29,6 @@ func main() {
log.Println("Initialize server components...")
initMinify()
initMarkdown()
initCache()
err = initTemplateAssets() // Needs minify
if err != nil {
log.Fatal(err)