index page is caching

2 files changed, 69 insertions, 2 deletions

diff --git a/cache.go b/cache.go
new file mode 100644
index 0000000..88d5dba
--- /dev/null
+++ b/cache.go
@@ -0,0 +1,58 @@
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"sync"
+	"time"
+)
+
+// Holds the cached responses
+type page struct {
+	raw     []byte
+	expires time.Time
+}
+
+// Wraps the page cache map with a rwlock
+type cacheWrapper struct {
+	sync.RWMutex
+	pages map[string]*page
+}
+
+// The actual page/response cache
+var cache = &cacheWrapper{
+	pages: make(map[string]*page),
+}
+
+func bapCache(requestPath string) {
+	cache.RLock()
+	if cache.pages[requestPath] == nil {
+		cache.RUnlock()
+		cacheIndex()
+		return
+	}
+
+	expires := cache.pages[requestPath].expires
+	cache.RUnlock()
+
+	if time.Now().After(expires) {
+		cacheIndex()
+	}
+}
+
+// Pulls the index page from disk and places it into the cache.
+// etag is an fnv32 hash of the raw file bytes, truncated if necessary.
+func cacheIndex() {
+	bytes, err := ioutil.ReadFile("web/index.txt")
+	if err != nil {
+		log.Printf("Could not read index page: %s", err.Error())
+		bytes = []byte("tilde.institute informational API")
+	}
+
+	cache.Lock()
+	cache.pages["/"] = &page{
+		raw:     bytes,
+		expires: time.Now().Add(5 * time.Minute),
+	}
+	cache.Unlock()
+}
diff --git a/http.go b/http.go
index ab6050f..93b6d0c 100644
--- a/http.go
+++ b/http.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"net/http"
 	"strings"
+	"time"
 
 	"git.tilde.institute/tilde/api/internal/endpoints"
 )
@@ -77,8 +78,16 @@ func routingHop(r *http.Request) string {
 
 // Yeets the index/summary page to the user
 func indexHandler(w http.ResponseWriter, r *http.Request) {
-	w.Header().Add("Content-Type", mimePlain)
-	out := []byte("This is the tilde.institute informational API")
+	bapCache("/")
+	cache.RLock()
+	defer cache.RUnlock()
+
+	out := cache.pages["/"].raw
+	expires := cache.pages["/"].expires
+
+	w.Header().Set("Content-Type", mimePlain)
+	w.Header().Set("Expires", expires.Format(time.RFC1123))
+
 	_, err := w.Write(out)
 	if err != nil {
 		errHTTP(w, r, err, http.StatusInternalServerError)