From 01089da57a0a68d96641beb53fed73b4e08bfe9e Mon Sep 17 00:00:00 2001
From: Christine Dodrill <me@christine.website>
Date: Sat, 26 Jan 2019 06:38:22 -0800
Subject: [PATCH] cmd/site: etags

---
 Dockerfile        |  2 +-
 cmd/site/html.go  | 19 ++++++++++++++++---
 cmd/site/rss.go   |  1 +
 scripts/docker.sh |  2 +-
 4 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 307276b..79fc553 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM xena/go:1.11.1 AS build
+FROM xena/go:1.11.5 AS build
 ENV GOPROXY https://cache.greedo.xeserv.us
 COPY . /site
 WORKDIR /site
diff --git a/cmd/site/html.go b/cmd/site/html.go
index c851342..fe8d190 100644
--- a/cmd/site/html.go
+++ b/cmd/site/html.go
@@ -10,14 +10,24 @@ import (
 	"within.website/ln"
 )
 
-func logTemplateTime(name string, from time.Time) {
+func logTemplateTime(name string, f ln.F, from time.Time) {
 	now := time.Now()
-	ln.Log(context.Background(), ln.F{"action": "template_rendered", "dur": now.Sub(from).String(), "name": name})
+	ln.Log(context.Background(), f, ln.F{"action": "template_rendered", "dur": now.Sub(from).String(), "name": name})
 }
 
 func (s *Site) renderTemplatePage(templateFname string, data interface{}) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		defer logTemplateTime(templateFname, time.Now())
+		fetag := "W/" + Hash(templateFname, etag) + "-1"
+
+		f := ln.F{"etag": fetag, "if-none-match": r.Header.Get("If-None.Match")}
+
+		if r.Header.Get("If-None-Match") == fetag {
+			http.Error(w, "Cached data OK", http.StatusNotModified)
+			ln.Log(r.Context(), f, ln.Info("Cache hit"))
+			return
+		}
+
+		defer logTemplateTime(templateFname, f, time.Now())
 		s.tlock.RLock()
 		defer s.tlock.RUnlock()
 
@@ -43,6 +53,9 @@ func (s *Site) renderTemplatePage(templateFname string, data interface{}) http.H
 			t = s.templates[templateFname]
 		}
 
+		w.Header().Set("ETag", fetag)
+		w.Header().Set("Cache-Control", "max-age=432000")
+
 		err = t.Execute(w, data)
 		if err != nil {
 			panic(err)
diff --git a/cmd/site/rss.go b/cmd/site/rss.go
index b1845cd..935749f 100644
--- a/cmd/site/rss.go
+++ b/cmd/site/rss.go
@@ -9,6 +9,7 @@ import (
 )
 
 var bootTime = time.Now()
+var etag = Hash(bootTime.String(), IncrediblySecureSalt)
 
 // IncrediblySecureSalt *******
 const IncrediblySecureSalt = "hunter2"
diff --git a/scripts/docker.sh b/scripts/docker.sh
index 05e4c88..8eb3c20 100755
--- a/scripts/docker.sh
+++ b/scripts/docker.sh
@@ -3,4 +3,4 @@
 set -e
 
 docker build -t xena/site .
-docker run --rm -itp 5000:5000 -e PORT=5000 xena/site
+exec docker run --rm -itp 5000:5000 -e PORT=5000 xena/site