avoid possible metadata subscription data loss

Previous implementation append filer logs into one file. So one file is not always sorted, which can lead to miss reading some entries, especially when different filers have different write throughput.

weed/util/file_util.go

@@ -87,3 +87,11 @@ func ResolvePath(path string) string {
 
 	return path
 }
+
+func FileNameBase(filename string) string {
+	lastDotIndex := strings.LastIndex(filename, ".")
+	if lastDotIndex < 0 {
+		return filename
+	}
+	return filename[:lastDotIndex]
+}