Add cache purge

Signed-off-by: jolheiser <john.olheiser@gmail.com>

.woodpecker.yml

@@ -1,7 +1,3 @@
-clone:
-  git:
-    image: docker.io/a6543/test_git_plugin:latest
-
 pipeline:
   compliance:
     image: golang:1.17

overlay.go

@@ -98,3 +98,13 @@ func WithSub(sub string) Option {
 		return
 	}
 }
+
+// WithCaching sets a caching mode for an FS
+// Caching avoids subsequent os.Stat to determine if a file exists on disk
+// See bench.txt for differences in usage
+func WithCaching(doCache bool) Option {
+	return func(x *FS) error {
+		x.doCache = doCache
+		return nil
+	}
+}