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

common/dirwalk/tests/tools/gendir/generate.go

Index: common/dirwalk/tests/tools/gendir/generate.go
diff --git a/common/dirwalk/tests/tools/gendir/generate.go b/common/dirwalk/tests/tools/gendir/generate.go
new file mode 100644
index 0000000000000000000000000000000000000000..87512c2a2f0baf0b5ad9a42f1a94a013457cc572
--- /dev/null
+++ b/common/dirwalk/tests/tools/gendir/generate.go
@@ -0,0 +1,179 @@
+// 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"
+	"log"
+	"math/rand"
+	"os"
+	"path"
+
+	"github.com/dustin/go-humanize"
+)
+
+const (
+	BLOCKSIZE uint64 = 1 * 1024 * 1024 // 1 Megabyte
+)
+
+func writeFile(filename string, filecontent io.Reader, filesize uint64) {
+	f, err := os.Create(filename)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer f.Close()
+
+	var written uint64 = 0
+	for written < filesize {
+		content := make([]byte, min(filesize-written, BLOCKSIZE))
+
+		// Generate a block of content
+		read, err := filecontent.Read(content)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		// Write the block of content
+		write, err := f.Write(content[0:read])
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		written += uint64(write)
+	}
+}
+
+const (
+	FILENAME_MINSIZE uint64 = 4
+	FILENAME_MAXSIZE uint64 = 20
+)
+
+type FileType int
+
+const (
+	FILETYPE_BIN_RAND   FileType = iota // Truly random binary data (totally uncompressible)
+	FILETYPE_TXT_RAND                   // Truly random text data (mostly uncompressible)
+	FILETYPE_BIN_REPEAT                 // Repeated binary data (compressible)
+	FILETYPE_TXT_REPEAT                 // Repeated text data (very compressible)
+	FILETYPE_TXT_LOREM                  // Lorem Ipsum txt data (very compressible)
+
+	FILETYPE_MAX
+)
+
+var FileTypeName []string = []string{
+	"Random Binary",
+	"Random Text",
+	"Repeated Binary",
+	"Repeated Text",
+	"Lorem Text",
+}
+
+func (f FileType) String() string {
+	return FileTypeName[int(f)]
+}
+
+// Generate num files between (min, max) size
+func generateFiles(r *rand.Rand, dir string, num uint64, filesize_min uint64, filesize_max uint64) {
+	for i := uint64(0); i < num; i++ {
+		var filename string
+		var filepath string
+		for true {
+			filename = filenameRandom(r, randBetween(r, FILENAME_MINSIZE, FILENAME_MAXSIZE))
+			filepath = path.Join(dir, filename)
+			if _, err := os.Stat(filepath); os.IsNotExist(err) {
+				break
+			}
+		}
+		filesize := randBetween(r, filesize_min, filesize_max)
+		filetype := FileType(r.Intn(int(FILETYPE_MAX)))
+
+		var filecontent io.Reader
+		switch filetype {
+		case FILETYPE_BIN_RAND:
+			filecontent = RandomBinaryGenerator(r)
+		case FILETYPE_TXT_RAND:
+			filecontent = RandomTextGenerator(r)
+		case FILETYPE_BIN_REPEAT:
+			filecontent = RepeatedBinaryGenerator(r)
+		case FILETYPE_TXT_REPEAT:
+			filecontent = RepeatedTextGenerator(r)
+		case FILETYPE_TXT_LOREM:
+			filecontent = LoremTextGenerator()
+		}
+
+		if num < 1000 {
+			fmt.Printf("File: %-40s %-20s (%s)\n", filename, filetype.String(), humanize.Bytes(filesize))
+		}
+		writeFile(filepath, filecontent, filesize)
+	}
+}
+
+// Generate num directories
+func generateDirs(r *rand.Rand, dir string, num uint64) []string {
+	var result []string
+
+	for i := uint64(0); i < num; i++ {
+		var dirname string
+		var dirpath string
+		for true {
+			dirname = filenameRandom(r, randBetween(r, FILENAME_MINSIZE, FILENAME_MAXSIZE))
+			dirpath = path.Join(dir, dirname)
+			if _, err := os.Stat(dirpath); os.IsNotExist(err) {
+				break
+			}
+		}
+
+		if err := os.MkdirAll(dirpath, 0755); err != nil {
+			log.Fatal(err)
+		}
+		result = append(result, dirpath)
+	}
+	return result
+}
+
+type FileSettings struct {
+	MinNumber uint64
+	MaxNumber uint64
+	MinSize   uint64
+	MaxSize   uint64
+}
+
+type DirSettings struct {
+	Number       []uint64
+	MinFileDepth uint64
+}
+
+type TreeSettings struct {
+	Files []FileSettings
+	Dir   DirSettings
+}
+
+func generateTreeInternal(r *rand.Rand, dir string, depth uint64, settings *TreeSettings) {
+	fmt.Printf("%04d:%s -->\n", depth, dir)
+	// Generate the files in this directory
+	if depth >= settings.Dir.MinFileDepth {
+		for _, files := range settings.Files {
+			numfiles := randBetween(r, files.MinNumber, files.MaxNumber)
+			fmt.Printf("%04d:%s: Generating %d files (between %s and %s)\n", depth, dir, numfiles, humanize.Bytes(files.MinSize), humanize.Bytes(files.MaxSize))
+			generateFiles(r, dir, numfiles, files.MinSize, files.MaxSize)
+		}
+	}
+
+	// Generate another depth of directories
+	if depth < uint64(len(settings.Dir.Number)) {
+		numdirs := settings.Dir.Number[depth]
+		fmt.Printf("%04d:%s: Generating %d directories\n", depth, dir, numdirs)
+		for _, childpath := range generateDirs(r, dir, numdirs) {
+			generateTreeInternal(r, childpath, depth+1, settings)
+		}
+	}
+	fmt.Printf("%04d:%s <--\n", depth, dir)
+}
+
+func GenerateTree(r *rand.Rand, rootdir string, settings *TreeSettings) {
+	generateTreeInternal(r, rootdir, 0, settings)
+	return
+}