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Add in-memory cache to GET requests, purges on successful POSTs

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This commit is contained in:
Brian Picciano 2022-05-21 10:04:50 -06:00
parent 1de0ab3b72
commit fb905ad53c
4 changed files with 103 additions and 13 deletions
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1
srv/src/go.mod
View File

@ -10,6 +10,7 @@ require (
github.com/google/uuid v1.3.0
github.com/gorilla/feeds v1.1.1 // indirect
github.com/gorilla/websocket v1.4.2
github.com/hashicorp/golang-lru v0.5.4 // indirect
github.com/mattn/go-sqlite3 v1.14.8
github.com/mediocregopher/mediocre-go-lib/v2 v2.0.0-beta.0.0.20220506011745-cbeee71cb1ee
github.com/mediocregopher/radix/v4 v4.0.0-beta.1.0.20210726230805-d62fa1b2e3cb

2
srv/src/go.sum
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@ -75,6 +75,8 @@ github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgf
github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
github.com/hashicorp/go-multierror v1.0.0/go.mod h1:dHtQlpGsu+cZNNAkkCN/P3hoUDHhCYQXV3UM06sGGrk=
github.com/hashicorp/golang-lru v0.5.4 h1:YDjusn29QI/Das2iO9M0BHnIbxPeyuCHsjMW+lJfyTc=
github.com/hashicorp/golang-lru v0.5.4/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
github.com/huandu/xstrings v1.3.2/go.mod h1:y5/lhBue+AyNmUVz9RLU9xbLR0o4KIIExikq4ovT0aE=
github.com/imdario/mergo v0.3.11/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=

14
srv/src/http/api.go
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@ -15,6 +15,7 @@ import (
"strings"
"time"
lru "github.com/hashicorp/golang-lru"
"github.com/mediocregopher/blog.mediocregopher.com/srv/cfg"
"github.com/mediocregopher/blog.mediocregopher.com/srv/chat"
"github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil"
@ -162,8 +163,11 @@ func (a *api) Shutdown(ctx context.Context) error {
func (a *api) handler() http.Handler {
requirePow := func(h http.Handler) http.Handler {
return a.requirePowMiddleware(h)
cache, err := lru.New(5000)
// instantiating the lru cache can't realistically fail
if err != nil {
panic(err)
}
mux := http.NewServeMux()
@ -172,12 +176,12 @@ func (a *api) handler() http.Handler {
apiMux := http.NewServeMux()
apiMux.Handle("/pow/challenge", a.newPowChallengeHandler())
apiMux.Handle("/pow/check",
requirePow(
a.requirePowMiddleware(
http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {}),
),
)
apiMux.Handle("/mailinglist/subscribe", requirePow(a.mailingListSubscribeHandler()))
apiMux.Handle("/mailinglist/subscribe", a.requirePowMiddleware(a.mailingListSubscribeHandler()))
apiMux.Handle("/mailinglist/finalize", a.mailingListFinalizeHandler())
apiMux.Handle("/mailinglist/unsubscribe", a.mailingListUnsubscribeHandler())
@ -222,10 +226,12 @@ func (a *api) handler() http.Handler {
"GET": applyMiddlewares(
globalHandler,
logReqMiddleware,
cacheMiddleware(cache),
setCSRFMiddleware,
),
"*": applyMiddlewares(
globalHandler,
purgeCacheOnOKMiddleware(cache),
authMiddleware(a.auther),
checkCSRFMiddleware,
addResponseHeadersMiddleware(map[string]string{

99
srv/src/http/middleware.go
View File

@ -1,10 +1,14 @@
package http
import (
"bytes"
"net"
"net/http"
"path/filepath"
"sync"
"time"
lru "github.com/hashicorp/golang-lru"
"github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil"
"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
@ -52,33 +56,33 @@ func setLoggerMiddleware(logger *mlog.Logger) middleware {
}
}
type logResponseWriter struct {
type wrappedResponseWriter struct {
http.ResponseWriter
http.Hijacker
statusCode int
}
func newLogResponseWriter(rw http.ResponseWriter) *logResponseWriter {
func newWrappedResponseWriter(rw http.ResponseWriter) *wrappedResponseWriter {
h, _ := rw.(http.Hijacker)
return &logResponseWriter{
return &wrappedResponseWriter{
ResponseWriter: rw,
Hijacker: h,
statusCode: 200,
}
}
func (lrw *logResponseWriter) WriteHeader(statusCode int) {
lrw.statusCode = statusCode
lrw.ResponseWriter.WriteHeader(statusCode)
func (rw *wrappedResponseWriter) WriteHeader(statusCode int) {
rw.statusCode = statusCode
rw.ResponseWriter.WriteHeader(statusCode)
}
func logReqMiddleware(h http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
lrw := newLogResponseWriter(rw)
wrw := newWrappedResponseWriter(rw)
started := time.Now()
h.ServeHTTP(lrw, r)
h.ServeHTTP(wrw, r)
took := time.Since(started)
type logCtxKey string
@ -86,7 +90,7 @@ func logReqMiddleware(h http.Handler) http.Handler {
ctx := r.Context()
ctx = mctx.Annotate(ctx,
logCtxKey("took"), took.String(),
logCtxKey("response_code"), lrw.statusCode,
logCtxKey("response_code"), wrw.statusCode,
)
apiutil.GetRequestLogger(r).Info(ctx, "handled HTTP request")
@ -106,3 +110,80 @@ func disallowGetMiddleware(h http.Handler) http.Handler {
rw.WriteHeader(405)
})
}
type cacheResponseWriter struct {
*wrappedResponseWriter
buf *bytes.Buffer
}
func newCacheResponseWriter(rw http.ResponseWriter) *cacheResponseWriter {
return &cacheResponseWriter{
wrappedResponseWriter: newWrappedResponseWriter(rw),
buf: new(bytes.Buffer),
}
}
func (rw *cacheResponseWriter) Write(b []byte) (int, error) {
if _, err := rw.buf.Write(b); err != nil {
panic(err)
}
return rw.wrappedResponseWriter.Write(b)
}
func cacheMiddleware(cache *lru.Cache) middleware {
type entry struct {
body []byte
createdAt time.Time
}
pool := sync.Pool{
New: func() interface{} { return new(bytes.Reader) },
}
return func(h http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
id := r.URL.RequestURI()
if val, ok := cache.Get(id); ok {
entry := val.(entry)
reader := pool.Get().(*bytes.Reader)
defer pool.Put(reader)
reader.Reset(entry.body)
http.ServeContent(
rw, r, filepath.Base(r.URL.Path), entry.createdAt, reader,
)
return
}
cacheRW := newCacheResponseWriter(rw)
h.ServeHTTP(cacheRW, r)
if cacheRW.statusCode == 200 {
cache.Add(id, entry{
body: cacheRW.buf.Bytes(),
createdAt: time.Now(),
})
}
})
}
}
func purgeCacheOnOKMiddleware(cache *lru.Cache) middleware {
return func(h http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
wrw := newWrappedResponseWriter(rw)
h.ServeHTTP(wrw, r)
if wrw.statusCode == 200 {
cache.Purge()
}
})
}
}