From c1c1bb2c4c1baf37dbcce96f144966d4ada65ac5 Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Mon, 23 Jan 2023 22:30:30 +0100
Subject: Implement cache and logger middlewares for gemini

---
 src/http/apiutil/apiutil.go |  3 +++
 src/http/http.go            | 14 ++++----------
 src/http/middleware.go      | 23 ++++++++++++++---------
 3 files changed, 21 insertions(+), 19 deletions(-)

(limited to 'src/http')

diff --git a/src/http/apiutil/apiutil.go b/src/http/apiutil/apiutil.go
index 1fbadea..c59104c 100644
--- a/src/http/apiutil/apiutil.go
+++ b/src/http/apiutil/apiutil.go
@@ -16,6 +16,9 @@ import (
 	"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
 )
 
+// TODO I don't think Set/GetRequestLogger are necessary? Seems sufficient to
+// just annotate the request's context
+
 type loggerCtxKey int
 
 // SetRequestLogger sets the given Logger onto the given Request's Context,
diff --git a/src/http/http.go b/src/http/http.go
index 98cdde3..d51671d 100644
--- a/src/http/http.go
+++ b/src/http/http.go
@@ -15,7 +15,7 @@ import (
 	"strings"
 	"time"
 
-	lru "github.com/hashicorp/golang-lru"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/cache"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/cfg"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/mailinglist"
@@ -33,6 +33,7 @@ var staticFS embed.FS
 type Params struct {
 	Logger     *mlog.Logger
 	PowManager pow.Manager
+	Cache      cache.Cache
 
 	PostStore      post.Store
 	PostAssetStore post.AssetStore
@@ -190,13 +191,6 @@ func (a *api) apiHandler() http.Handler {
 
 func (a *api) blogHandler() http.Handler {
 
-	cache, err := lru.New(5000)
-
-	// instantiating the lru cache can't realistically fail
-	if err != nil {
-		panic(err)
-	}
-
 	mux := http.NewServeMux()
 
 	mux.Handle("/posts/", http.StripPrefix("/posts",
@@ -244,11 +238,11 @@ func (a *api) blogHandler() http.Handler {
 
 	readOnlyMiddlewares := []middleware{
 		logReqMiddleware, // only log GETs on cache miss
-		cacheMiddleware(cache),
+		cacheMiddleware(a.params.Cache, a.params.PublicURL),
 	}
 
 	readWriteMiddlewares := []middleware{
-		purgeCacheOnOKMiddleware(cache),
+		purgeCacheOnOKMiddleware(a.params.Cache),
 		authMiddleware(a.auther),
 	}
 
diff --git a/src/http/middleware.go b/src/http/middleware.go
index b82fc29..a21511f 100644
--- a/src/http/middleware.go
+++ b/src/http/middleware.go
@@ -4,11 +4,12 @@ import (
 	"bytes"
 	"net"
 	"net/http"
+	"net/url"
 	"path/filepath"
 	"sync"
 	"time"
 
-	lru "github.com/hashicorp/golang-lru"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/cache"
 	"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"
@@ -86,6 +87,9 @@ func (rw *wrappedResponseWriter) WriteHeader(statusCode int) {
 }
 
 func logReqMiddleware(h http.Handler) http.Handler {
+
+	type logCtxKey string
+
 	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
 
 		wrw := newWrappedResponseWriter(rw)
@@ -94,8 +98,6 @@ func logReqMiddleware(h http.Handler) http.Handler {
 		h.ServeHTTP(wrw, r)
 		took := time.Since(started)
 
-		type logCtxKey string
-
 		ctx := r.Context()
 		ctx = mctx.Annotate(ctx,
 			logCtxKey("took"), took.String(),
@@ -139,7 +141,7 @@ func (rw *cacheResponseWriter) Write(b []byte) (int, error) {
 	return rw.wrappedResponseWriter.Write(b)
 }
 
-func cacheMiddleware(cache *lru.Cache) middleware {
+func cacheMiddleware(cache cache.Cache, publicURL *url.URL) middleware {
 
 	type entry struct {
 		body      []byte
@@ -153,11 +155,14 @@ func cacheMiddleware(cache *lru.Cache) middleware {
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
 
-			id := r.URL.RequestURI()
+			// r.URL doesn't have Scheme or Host populated, better to add the
+			// public url to the key to make sure there's no possiblity of
+			// collision with other protocols using the cache.
+			id := publicURL.String() + "|" + r.URL.String()
 
-			if val, ok := cache.Get(id); ok {
+			if value := cache.Get(id); value != nil {
 
-				entry := val.(entry)
+				entry := value.(entry)
 
 				reader := pool.Get().(*bytes.Reader)
 				defer pool.Put(reader)
@@ -174,7 +179,7 @@ func cacheMiddleware(cache *lru.Cache) middleware {
 			h.ServeHTTP(cacheRW, r)
 
 			if cacheRW.statusCode == 200 {
-				cache.Add(id, entry{
+				cache.Set(id, entry{
 					body:      cacheRW.buf.Bytes(),
 					createdAt: time.Now(),
 				})
@@ -183,7 +188,7 @@ func cacheMiddleware(cache *lru.Cache) middleware {
 	}
 }
 
-func purgeCacheOnOKMiddleware(cache *lru.Cache) middleware {
+func purgeCacheOnOKMiddleware(cache cache.Cache) middleware {
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
 
-- 
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