use LRU cache package

Thumbnailer.go

@@ -2,53 +2,49 @@ package thumbnail
 
 import (
 	"fmt"
-	"image"
 	"image/jpeg"
 	"image/png"
 	"os"
 	"strings"
-	"sync"
+
+	lru "github.com/hashicorp/golang-lru"
 )
 
 type Thumbnailer struct {
 	Width  int
 	Height int
-	MaxCacheSize int
 
-	cacheMtx   sync.RWMutex
-	thumbCache map[string][]byte
+	thumbCache *lru.Cache // threadsafe
 }
 
-func NewThumbnailer() *Thumbnailer {
+func NewThumbnailer(Width, Height, MaxCacheSize int) *Thumbnailer {
+	thumbCache, err := lru.New(MaxCacheSize)
+	if err != nil {
+		panic(err)
+	}
+
 	return &Thumbnailer{
-		Width:        100,
-		Height:       100,
-		MaxCacheSize: 10,
-		thumbCache:   make(map[string][]byte, 0),
+		Width:      Width,
+		Height:     Height,
+		thumbCache: thumbCache,
 	}
 }
 
 func (this *Thumbnailer) RenderFile(absPath string) ([]byte, error) {
-	this.cacheMtx.RLock()
-	tcache, ok := this.thumbCache[absPath]
-	this.cacheMtx.RUnlock()
 
+	thumb, ok := this.thumbCache.Get(absPath)
 	if ok {
-		return tcache, nil
+		return thumb.([]byte), nil
 	}
 
 	// Add to cache
-	tcache, err := this.RenderFile_NoCache(absPath)
+	thumb, err := this.RenderFile_NoCache(absPath)
 	if err != nil {
 		return nil, err
 	}
 
-	this.cacheMtx.Lock()
-	// FIXME prune old cached thumbnails
-	this.thumbCache[absPath] = tcache
-	this.cacheMtx.Unlock()
-
-	return tcache, nil
+	this.thumbCache.Add(absPath, thumb)
+	return thumb.([]byte), nil
 }
 
 func (this *Thumbnailer) RenderFile_NoCache(absPath string) ([]byte, error) {