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

common/dirwalk/tests/tools/walkdir/walkers_size.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 (
+        "fmt"
+        "io"
+        "os"
+)
+
+// SizeWalker implements Walker. It prints the size of every file.
+type SizeWalker struct {
+        BaseWalker
+        obuf io.Writer
+}
+
+func (s *SizeWalker) SizeFile(filename string, size int64) {
+        fmt.Fprintf(s.obuf, "%s: %d\n", filename, size)
+}
+
+func (s *SizeWalker) SmallFile(filename string, alldata []byte) {
+        s.BaseWalker.SmallFile(filename, alldata)
+        s.SizeFile(filename, int64(len(alldata)))
+}
+
+func (s *SizeWalker) LargeFile(filename string) {
+        s.BaseWalker.LargeFile(filename)
+        stat, err := os.Stat(filename)
+        if err != nil {
+                s.Error(filename, err)
+        } else {
+                s.SizeFile(filename, stat.Size())
+        }
+}