Remove empty (invalid) entries from the cache

utils/cache/file_hauter_test.go

@@ -0,0 +1,81 @@
+package cache_test
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/djherbis/fscache"
+	"github.com/navidrome/navidrome/utils/cache"
+)
+
+func TestFileHaunterMaxSize(t *testing.T) {
+	tempDir, _ := os.MkdirTemp("", "spread_fs")
+	cacheDir := filepath.Join(tempDir, "cache1")
+	fs, err := fscache.NewFs(cacheDir, 0700)
+	if err != nil {
+		t.Error(err.Error())
+		t.FailNow()
+	}
+	defer os.RemoveAll(tempDir)
+
+	c, err := fscache.NewCacheWithHaunter(fs, fscache.NewLRUHaunterStrategy(cache.NewFileHaunter(0, 24, 400*time.Millisecond)))
+	if err != nil {
+		t.Error(err.Error())
+		return
+	}
+	defer c.Clean() //nolint:errcheck
+
+	// Create 5 normal files and 1 empty
+	for i := 0; i < 6; i++ {
+		name := fmt.Sprintf("stream-%v", i)
+		var r fscache.ReadAtCloser
+		if i < 5 {
+			r = createCachedStream(c, name, "hello")
+		} else { // Last one is empty
+			r = createCachedStream(c, name, "")
+		}
+
+		if !c.Exists(name) {
+			t.Errorf(name + " should exist")
+		}
+
+		<-time.After(10 * time.Millisecond)
+
+		err := r.Close()
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	<-time.After(400 * time.Millisecond)
+
+	if c.Exists("stream-0") {
+		t.Errorf("stream-0 should have been scrubbed")
+	}
+
+	if c.Exists("stream-5") {
+		t.Errorf("stream-5 should have been scrubbed")
+	}
+
+	files, err := os.ReadDir(cacheDir)
+	if err != nil {
+		t.Error(err.Error())
+		return
+	}
+
+	if len(files) != 4 {
+		t.Errorf("expected 4 items in directory")
+	}
+}
+
+func createCachedStream(c *fscache.FSCache, name string, contents string) fscache.ReadAtCloser {
+	r, w, _ := c.Get(name)
+	_, _ = w.Write([]byte(contents))
+	_ = w.Close()
+	_, _ = io.Copy(io.Discard, r)
+	return r
+}