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

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

Index: common/dirwalk/tests/tools/walkdir/fileprocessor_hash.go
diff --git a/common/dirwalk/tests/tools/walkdir/fileprocessor_hash.go b/common/dirwalk/tests/tools/walkdir/fileprocessor_hash.go
new file mode 100644
index 0000000000000000000000000000000000000000..2a6612395f9c5dc463a5244797705c8c79b4daa3
--- /dev/null
+++ b/common/dirwalk/tests/tools/walkdir/fileprocessor_hash.go
@@ -0,0 +1,36 @@
+// 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 (
+	"fmt"
+	"io"
+)
+
+// HashFileProcessor implements FileProcessor. It generates a hash for the contents of each
+// found file.
+type HashFileProcessor struct {
+	BaseFileProcessor
+	obuf io.Writer
+}
+
+func (p *HashFileProcessor) HashedFile(path string, r io.Reader) {
+	digest, _, err := hash(r)
+	if err != nil {
+		p.Error(path, err)
+		return
+	}
+	fmt.Fprintf(p.obuf, "%s: %v\n", path, digest)
+}
+
+func (p *HashFileProcessor) SmallFile(path string, r io.ReadCloser) {
+	p.HashedFile(path, r)
+	p.BaseFileProcessor.SmallFile(path, r)
+}
+
+func (p *HashFileProcessor) LargeFile(path string, r io.ReadCloser) {
+	p.HashedFile(path, r)
+	p.BaseFileProcessor.LargeFile(path, r)
+}