A tool to evaluate methods in creating temp files

tools/win/CreateTempFilesPerfEvaluation/CreateTempFilesPerfEval.cc

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <windows.h>
+
+#include <shlwapi.h>
+#include <stdio.h>
+#include <tchar.h>
+
+#include <algorithm>
+#include <iostream>
+#include <sstream>
+#include <string>
+
+#pragma warning(disable : 4996)
+
+// Create |count| number of temp files at |folder_path| usingGUID based method.
+// The time cost in millisecond of creating every 500 temp files or all the
+// files if |count| < 500 is printed to the console.
+bool CreateFilesUsingGuid(UINT count, const char* folder_path);
+
+// Create |count| number of temp files at |folder_path| using GetTempFileName()
+// API. The time cost in millisecond of creating every 500 temp files or all the
+// files if |count| < 500 is printed to the console.
+bool CreateFilesUsingGetTempFileName(UINT count, const char* folder_path);
+
+// This method converts GUID to a string.
+char* ConvertGuidToString(const GUID* id, char* out);
+
+// Check if the given directory exists and is empty. If it doesn't exist, try to
+// create it.
+bool IsDirectoryReadyExistedAndEmpty(const char* folder_path);
+
+// Deletes all the content in |folder_path|.
+void DeleteDirectoryContent(const char* folder_path);
+
+// Deletes |folder_path| including its contents and the raw directory.
+bool DeleteDirectory(const char* folder_path);
+
+// Deletes |folder_path| including its contents and the raw directory, and print
+// the delete status to the console.
+void DeleteDirectoryAndPrintMsg(const char* folder_path);
+
+// Maximum number of temp files allowed to create. This is limited by the
+// implementation of GetTempFileName().
+// "This limits GetTempFileName to a maximum of 65,535 unique file names if the
+// lpPathName and lpPrefixString parameters remain the same."
+// https://msdn.microsoft.com/en-us/library/windows/desktop/aa364991(v=vs.85).aspx
+UINT kMaxFileCreate = 65535;
+
+int main() {
+  // Gets the temp path env string.
+  DWORD temp_path_ret = 0;
+  CHAR temp_folder_path[MAX_PATH];
+  temp_path_ret = ::GetTempPathA(MAX_PATH, temp_folder_path);
+  if (temp_path_ret > MAX_PATH || temp_path_ret == 0) {
+    std::cout << "GetTempPath failed" << std::endl;
+    return 0;
+  }
+
+  // A temporary directory where the new temp files created by GetTempFileName()
+  // are written.
+  std::string temp_dir_gettempfilename(
+      std::string(temp_folder_path).append("TempDirGetTempFileName\\"));
+
+  // A temporary directory where the new temp files created by Guid-based method
+  // are written.
+  std::string temp_dir_guid(
+      std::string(temp_folder_path).append("TempDirGuid\\"));
+
+  UINT file_create_count;
+  std::string user_input;
+
+  while (true) {
+    std::cout << "\nPlease enter # of files to create (maximum "
+              << kMaxFileCreate << "), or \"quit\" to end the program : ";
+    std::getline(std::cin, user_input);
+
+    std::transform(user_input.begin(), user_input.end(), user_input.begin(),
+                   ::tolower);
+    if (user_input == "quit")
+      break;
+
+    std::cout << std::endl;
+    std::stringstream ss(user_input);
+
+    if (ss >> file_create_count && file_create_count <= kMaxFileCreate) {
+      std::cout << "\nPlease select method to create temp file names,\n"
+                << "\"t\" for GetTempFileName \n"
+                << "\"g\" for GUID-based \n"
+                << "\"b\" for both \n"
+                << "or \"quit\" to end the program : ";
+      std::getline(std::cin, user_input);
+
+      std::transform(user_input.begin(), user_input.end(), user_input.begin(),
+                     ::tolower);
+      if (user_input == "quit")
+        break;
+
+      if (user_input == "t" || user_input == "b") {
+        std::cout << "\nGetTempFileName :" << std::endl;
+        if (CreateFilesUsingGetTempFileName(file_create_count,
+                                            temp_dir_gettempfilename.c_str())) {
+          std::cout << "File creation succeeds at " << temp_dir_gettempfilename
+                    << ", now clean all of them!" << std::endl;
+        }
+        DeleteDirectoryAndPrintMsg(temp_dir_gettempfilename.c_str());
+      }
+
+      if (user_input == "g" || user_input == "b") {
+        std::cout << "\nGUID-based :" << std::endl;
+        if (CreateFilesUsingGuid(file_create_count, temp_dir_guid.c_str())) {
+          std::cout << "File creation succeeds at " << temp_dir_guid
+                    << ", now clean all of them!" << std::endl;
+        }
+        DeleteDirectoryAndPrintMsg(temp_dir_guid.c_str());
+      }
+    } else {
+      std::cout << "Input number is invalid, please enter # of files to create "
+                   "(maximum "
+                << kMaxFileCreate << "), or \"quit\" to end the program : ";
+    }
+    std::cout << std::endl;
+  }
+  return 0;
+}
+
+bool CreateFilesUsingGuid(UINT count, const char* dir_path) {
+  if (!IsDirectoryReadyExistedAndEmpty(dir_path))
+    return false;
+
+  LARGE_INTEGER starting_time, ending_time, elapsed_ms;
+  ::QueryPerformanceCounter(&starting_time);
+  LARGE_INTEGER frequency;
+  ::QueryPerformanceFrequency(&frequency);
+
+  for (UINT i = 1; i <= count; ++i) {
+    GUID guid;
+    HRESULT hCreateGuid = ::CoCreateGuid(&guid);
+    char buffer[37];
+    ConvertGuidToString(&guid, buffer);
+    std::string temp_name = std::string(dir_path).append(buffer).append(".tmp");
+
+    HANDLE file_handle =
+        ::CreateFileA(temp_name.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL,
+                      CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+    ::CloseHandle(file_handle);
+
+    if (i % 500 == 0 || i == count) {
+      ::QueryPerformanceCounter(&ending_time);
+      // Convert the elapsed number of ticks to milliseconds.
+      elapsed_ms.QuadPart = (ending_time.QuadPart - starting_time.QuadPart) *
+                            1000 / frequency.QuadPart;
+
+      starting_time = ending_time;
+      std::cout << i << " / " << count << " --- " << elapsed_ms.QuadPart
+                << " ms" << std::endl;
+    }
+  }
+  return true;
+}
+
+bool CreateFilesUsingGetTempFileName(UINT count, const char* dir_path) {
+  if (!IsDirectoryReadyExistedAndEmpty(dir_path))
+    return false;
+
+  CHAR temp_name[MAX_PATH];
+  LARGE_INTEGER starting_time, ending_time, elapsed_ms;
+  ::QueryPerformanceCounter(&starting_time);
+  LARGE_INTEGER frequency;
+  ::QueryPerformanceFrequency(&frequency);
+
+  for (UINT i = 1; i <= count; ++i) {
+    ::GetTempFileNameA(dir_path, "", 0, temp_name);
+    if (i % 500 == 0 || i == count) {
+      ::QueryPerformanceCounter(&ending_time);
+      // Convert the elapsed number of ticks to milliseconds.
+      elapsed_ms.QuadPart = (ending_time.QuadPart - starting_time.QuadPart) *
+                            1000 / frequency.QuadPart;
+
+      starting_time = ending_time;
+      std::cout << i << " / " << count << " --- " << elapsed_ms.QuadPart

[stanisc, 2017/04/14 23:30:54]

Printing out to the console takes some non-trivial time. It would be better to
take a new time snapshot after this line to exclude the console printing time.

[chengx, 2017/04/17 19:00:57]

You're right! Done.

[stanisc, 2017/04/17 22:36:09]

The same issue still exists in CreateFilesUsingGuid

[chengx, 2017/04/17 23:12:16]

Ah, I forgot. Now it's fixed.

+                << " ms" << std::endl;
+    }
+  }
+  return true;
+}
+
+char* ConvertGuidToString(const GUID* id, char* out) {
+  int i;
+  char* ret = out;
+  out += sprintf(out, "%.8lX-%.4hX-%.4hX-", id->Data1, id->Data2, id->Data3);
+  for (i = 0; i < sizeof(id->Data4); ++i) {
+    out += sprintf(out, "%.2hhX", id->Data4[i]);
+    if (i == 1)
+      *(out++) = '-';
+  }
+  return ret;
+}
+
+bool IsDirectoryReadyExistedAndEmpty(const char* folder_path) {

[stanisc, 2017/04/14 23:30:54]

The function name is somewhat confusing. Please consider renaming it something
like CreateOrValidateTempDirectory.

[chengx, 2017/04/17 19:00:57]

Done.

+  if (::PathFileExistsA(folder_path)) {
+    if (!::PathIsDirectoryEmptyA(folder_path)) {
+      std::cout << folder_path
+                << " directory is not empty, please remove all its content.";
+      return false;
+    }
+    return true;
+  } else if (::CreateDirectoryA(folder_path, NULL) == 0) {
+    std::cout << folder_path << "directory creation fails.";
+    return false;
+  } else {
+    return true;
+  }
+}
+
+void DeleteDirectoryContent(const char* folder_path) {
+  char fileFound[256];

[stanisc, 2017/04/14 23:30:54]

Use MAX_PATH instead.

[chengx, 2017/04/17 19:00:57]

Done.

+  WIN32_FIND_DATAA info;
+  HANDLE hp;
+  sprintf(fileFound, "%s\\*.*", folder_path);
+  hp = ::FindFirstFileA(fileFound, &info);
+  do {
+    if (!((strcmp(info.cFileName, ".") == 0) ||
+          (strcmp(info.cFileName, "..") == 0))) {

[stanisc, 2017/04/14 23:30:55]

I suggest using a pattern where you skip these files and continue i.e.
if (strcmp(info.cFileName, ".") == 0 ||
    strcmp(info.cFileName, "..") == 0) {
  continue;
}
Also this doesn't need some of the parenthesis. 

[chengx, 2017/04/17 19:00:57]

Done.

+      if ((info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) ==
+          FILE_ATTRIBUTE_DIRECTORY) {

[stanisc, 2017/04/14 23:30:55]

Do you really expect nested directories there? You tool doesn't create any
nested directories so perhaps it shouldn't delete them. Also since your tool
creates only *.tmp file perhaps it should delete only files with that extension.
Better be safe when deleting anything from the disk.

[brucedawson, 2017/04/14 23:36:15]

Or, when creating files track the names and then delete exactly the files that
you created.
A std::vector<std::string> that you resize to 65536 at the beginning should not
affect the results significantly (and should have a constant-time effect anyway)
and would then make the deletion code trivial.

[chengx, 2017/04/17 19:00:57]

Agree that sub-directories won't be created, so I will remove the related code.
Since all the .tmp files are created in a temporary folder created by this
program, I'll just delete the folder including all its contents. It won't delete
anything not created by this program.

+        std::string subFolder = folder_path;
+        subFolder.append("\\");
+        subFolder.append(info.cFileName);
+        DeleteDirectoryContent(subFolder.c_str());
+        ::RemoveDirectoryA(subFolder.c_str());
+      } else {
+        sprintf(fileFound, "%s\\%s", folder_path, info.cFileName);
+        BOOL retVal = ::DeleteFileA(fileFound);
+      }
+    }
+
+  } while (::FindNextFileA(hp, &info));
+  FindClose(hp);
+}
+
+bool DeleteDirectory(const char* folder_path) {
+  DeleteDirectoryContent(folder_path);
+  return ::RemoveDirectoryA(folder_path) != 0;
+}
+
+void DeleteDirectoryAndPrintMsg(const char* folder_path) {
+  if (DeleteDirectory(folder_path)) {
+    std::cout << folder_path << " directory is deleted!" << std::endl;
+  } else {
+    std::cout << "[Attention] " << folder_path
+              << " directory's deletion fails, please take a look by yourself!"
+              << std::endl;
+  }
+}