index page is caching

1 files changed, 58 insertions, 0 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()
+}