luci-go/common/dirwalk: Code for walking a directory tree efficiently

common/dirwalk/tests/tools/walkdir/util.go

+// Copyright 2016 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package main
+
+import (
+        "io"
+
+        "github.com/luci/luci-go/common/isolated"
+)
+
+func hash(src io.Reader) (isolated.HexDigest, uint64, error) {
+        h := isolated.GetHash()
+        bytes, err := io.Copy(h, src)
+        if err != nil {
+                return isolated.HexDigest(""), 0, err
+        }
+        return isolated.Sum(h), uint64(bytes), nil
+}