内容压缩增加繁忙（busy）检测

internal/compressions/errors.go

@@ -0,0 +1,14 @@
+// Copyright 2024 GoEdge CDN goedge.cdn@gmail.com. All rights reserved. Official site: https://goedge.cn .
+
+package compressions
+
+import "errors"
+
+var ErrIsBusy = errors.New("the system is busy for compression")
+
+func CanIgnore(err error) bool {
+	if err == nil {
+		return true
+	}
+	return errors.Is(err, ErrIsBusy)
+}