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

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

Index: common/dirwalk/tests/tools/walkdir/fileprocessor.go
diff --git a/common/dirwalk/tests/tools/walkdir/fileprocessor.go b/common/dirwalk/tests/tools/walkdir/fileprocessor.go
new file mode 100644
index 0000000000000000000000000000000000000000..64048e0b1ff24c1be2281a1a54564cdfba6eb568
--- /dev/null
+++ b/common/dirwalk/tests/tools/walkdir/fileprocessor.go
@@ -0,0 +1,63 @@
+// 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"
+	"log"
+	"sync/atomic"
+)
+
+// FileProcessor is a basic interface for processing files provided by the
+// directory walking functions.
+type FileProcessor interface {
+	// Dir is called when a directory has been finished.
+	Dir(path string)
+
+	// SmallFile is called for processing a file which has been classed as "small".
+	SmallFile(path string, r io.ReadCloser)
+
+	// LargeFile is called for processing a file which has been classed as "large".
+	LargeFile(path string, r io.ReadCloser)
+
+	// Error is called when an error occurs on a path.
+	Error(path string, err error)
+
+	// Finished is called when the directory walk is finished.
+	Finished()
+}
+
+// BaseFileProcessor implements FileProcessor and counts the number of files of
+// each type.
+type BaseFileProcessor struct {
+	smallFiles uint64
+	largeFiles uint64
+	dirs       uint64
+}
+
+func (p *BaseFileProcessor) Dir(path string) {
+	atomic.AddUint64(&p.dirs, 1)
+}
+
+func (p *BaseFileProcessor) SmallFile(path string, r io.ReadCloser) {
+	atomic.AddUint64(&p.smallFiles, 1)
+	if r != nil {
+		r.Close()
+	}
+}
+
+func (p *BaseFileProcessor) LargeFile(path string, r io.ReadCloser) {
+	atomic.AddUint64(&p.largeFiles, 1)
+	if r != nil {
+		r.Close()
+	}
+}
+
+func (p *BaseFileProcessor) Error(path string, err error) {
+	log.Fatalf("%s:%s", path, err)
+}
+
+func (p *BaseFileProcessor) Finished() {
+}