ShowThreadNames tool to get thread ID/name pairs in a Chrome process

tools/win/ShowThreadNames/ShowThreadNames.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 <stdio.h>
+#include <tchar.h>
+#include <tlhelp32.h>
+
+#include <algorithm>
+#include <iostream>
+#include <iterator>
+#include <map>
+#include <sstream>
+#include <string>
+
+// List all threads in a process specified.
+BOOL ListProcessThreadNames(DWORD dwOwnerPID);
+
+// The GetThreadDescription API is available since Windows 10, version 1607.

[stanisc, 2017/02/23 02:29:59]

Perhaps you should mention why you have to bind to the function this way rather
than just use the SDK.

[chengx, 2017/02/23 03:26:04]

Done.

+typedef HRESULT(WINAPI* GETTHREADDESCRIPTION)(HANDLE hThread,
+                                              PWSTR* threadDescription);
+
+template <typename A, typename B>
+std::pair<B, A> flip_pair(const std::pair<A, B>& p) {
+  return std::pair<B, A>(p.second, p.first);
+}
+
+template <typename A, typename B>
+std::multimap<B, A> flip_map(const std::map<A, B>& src) {
+  std::multimap<B, A> dst;
+  std::transform(src.begin(), src.end(), std::inserter(dst, dst.begin()),
+                 flip_pair<A, B>);
+  return dst;
+}
+
+int main(void) {
+  unsigned int processId;
+  std::string user_input;
+  while (true) {
+    std::cout
+        << "\nPlease enter the process Id, or \"quit\" to end the program : ";
+    std::getline(std::cin, user_input);
+    std::cout << std::endl;
+    if (user_input == "quit")
+      break;
+    std::stringstream ss(user_input);
+    if (ss >> processId) {
+      ListProcessThreadNames(processId);
+    } else {
+      std::cout << "input is invalid" << std::endl;
+    }
+    std::cout << std::endl;
+  }
+  return 0;
+}
+
+BOOL ListProcessThreadNames(DWORD dwOwnerPID) {
+  HMODULE kernel32dll = ::GetModuleHandle(L"Kernel32.dll");
+
+  if (!kernel32dll) {

[brucedawson, 2017/02/23 01:57:26]

I'd skip this error checking 'cause kernel32.dll will always be present.

[chengx, 2017/02/23 03:26:04]

Done.

+    std::cout << "Error: cannot find Kernel32.dll" << std::endl;
+    return (FALSE);
+  }
+
+  auto get_thread_description_func = reinterpret_cast<GETTHREADDESCRIPTION>(
+      ::GetProcAddress(kernel32dll, "GetThreadDescription"));
+
+  if (!get_thread_description_func) {
+    std::cout << "GetThreadDescription API is not available in current OS"
+              << std::endl;
+    return (FALSE);
+  }
+
+  HANDLE hThreadSnap = INVALID_HANDLE_VALUE;

[stanisc, 2017/02/23 02:29:59]

I'd suggest to not use Hungarian notation i.e. handle variable starting with h.
Use Chrome code naming convention instead.

[chengx, 2017/02/23 03:26:03]

Changed to threadSnap.

+  // Take a snapshot of all running threads
+  hThreadSnap = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);
+  if (hThreadSnap == INVALID_HANDLE_VALUE)
+    return (FALSE);
+
+  THREADENTRY32 te32;
+  te32.dwSize = sizeof(THREADENTRY32);
+
+  // Retrieve information about the first thread, and exit if unsuccessful
+  if (!Thread32First(hThreadSnap, &te32)) {
+    std::cout << "Thread32First() call failed" << std::endl;
+    CloseHandle(hThreadSnap);
+    return (FALSE);
+  }
+
+  // Walk the thread list of the system, and display ID and name about each
+  // thread associated with the process specified.
+  std::cout << "thread_ID   thread_name" << std::endl;
+  std::map<DWORD, std::wstring> id_name_map;
+  do {
+    if (te32.th32OwnerProcessID == dwOwnerPID) {
+      HANDLE threadHandle =
+          OpenThread(THREAD_ALL_ACCESS, FALSE, te32.th32ThreadID);

[brucedawson, 2017/02/23 01:57:26]

You can probably use THREAD_QUERY_LIMITED_INFORMATION or
THREAD_QUERY_INFORMATION

[chengx, 2017/02/23 03:26:03]

Done.

+      if (threadHandle) {
+        PWSTR data;
+        HRESULT hr = get_thread_description_func(threadHandle, &data);
+        if (SUCCEEDED(hr)) {
+          std::wstring data_w(data);
+          id_name_map[te32.th32ThreadID] = data_w;
+        } else {
+          std::cout << "GetThreadDescription API call failed" << std::endl;
+        }
+        CloseHandle(threadHandle);
+      }
+    }
+  } while (Thread32Next(hThreadSnap, &te32));
+
+  // reverse the map so now it is sorted by thread name.

[stanisc, 2017/02/23 02:29:59]

Nit: comments are supposed to be complete sentences - start with a capital
letter and end with a period. This applies to some other comments as well.

[chengx, 2017/02/23 03:26:04]

Done.

+  std::multimap<std::wstring, DWORD> name_id_map = flip_map(id_name_map);

[brucedawson, 2017/02/23 01:57:26]

If you're going to put it in a multimap<wstring,DWORD> you should just do that
directly instead of putting it in first in a multimap<DWORD,wstring>.

Or, alternately, append the pairs to a std::vector and then sort it. For
performance critical code this would be better because of much better memory
access patterns, but for this it is highly irrelevant, so do whichever is
simpler.

[chengx, 2017/02/23 03:26:03]

I will use multimap<wstring,DWORD> directly.

+
+  // show thread ID and name.
+  for (auto it = name_id_map.begin(); it != name_id_map.end(); ++it) {
+    std::cout << it->second << "\t";
+    std::wcout << it->first << std::endl;
+  }
+
+  // clean up the snapshot object.
+  CloseHandle(hThreadSnap);

[brucedawson, 2017/02/23 01:57:26]

For tidiness consider closing the handle as soon as you're done with it.

[chengx, 2017/02/23 03:26:04]

Done.

+  return (TRUE);
+}