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

common/dirwalk/tests/tools/walkdir/fileprocessor_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"
+        "io/ioutil"
+        "os"
+)
+
+// SizeFileProcessor implements FileProcessor. It prints the size of every file.
+type SizeFileProcessor struct {
+        BaseFileProcessor
+        obuf io.Writer
+}
+
+func (p *SizeFileProcessor) SizeFile(path string, size int64) {
+        fmt.Fprintf(p.obuf, "%s: %d\n", path, size)
+}
+
+func (p *SizeFileProcessor) SmallFile(path string, r io.ReadCloser) {
+        bytes, err := io.Copy(ioutil.Discard, r)
+        if err != nil {
+                p.Error(path, err)
+        }
+        p.SizeFile(path, int64(bytes))
+
+        p.BaseFileProcessor.SmallFile(path, r)
+}
+
+func (p *SizeFileProcessor) LargeFile(path string, r io.ReadCloser) {
+        fi, err := os.Stat(path)
+        if err != nil {
+                p.Error(path, err)
+        } else {
+                p.SizeFile(path, fi.Size())
+        }
+        p.BaseFileProcessor.LargeFile(path, r)
+}