caching support to buntdb

Signed-off-by: Avelino <avelinorun@gmail.com>

cache/buntdb.go

@@ -0,0 +1,61 @@
+package cache
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/avelino/slugify"
+	"github.com/prest/prest/config"
+	"github.com/tidwall/buntdb"
+)
+
+// BuntConnect connects to database BuntDB - used for caching
+func BuntConnect(key string) (db *buntdb.DB, err error) {
+	if key != "" {
+		// each url will have its own cache,
+		// this will avoid slowing down the cache base
+		// it is saved in a file on the file system
+		key = slugify.Slugify(key)
+	}
+	db, err = buntdb.Open(config.PrestConf.CacheStoragePath + key + config.PrestConf.CacheSufixFile)
+	if err != nil {
+		// in case of an error to open buntdb the prestd cache is forced to false
+		config.PrestConf.Cache = false
+	}
+	return
+}
+
+// BuntGet downloads the data - if any - that is in the buntdb (embeded cache database)
+// using response.URL as key
+func BuntGet(key string, w http.ResponseWriter) (cacheExist bool) {
+	db, _ := BuntConnect(key)
+	cacheExist = false
+	db.View(func(tx *buntdb.Tx) error {
+		val, err := tx.Get(key)
+		if err == nil {
+			cacheExist = true
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(val))
+		}
+		return nil
+	})
+	defer db.Close()
+	return
+}
+
+// BuntSet sets data as cache in buntdb (embeded cache database)
+// using response.URL as key
+func BuntSet(key, value string) {
+	if !config.PrestConf.Cache {
+		return
+	}
+	db, _ := BuntConnect(key)
+	db.Update(func(tx *buntdb.Tx) error {
+		tx.Set(key, value,
+			&buntdb.SetOptions{
+				Expires: true,
+				TTL:     time.Duration(config.PrestConf.CacheTime) * time.Minute})
+		return nil
+	})
+	defer db.Close()
+}