Fix potential race-condition _beginthread

ppapi/tests/pp_thread.h

 /* Copyright (c) 2011 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.
  */
 
 #ifndef PPAPI_TESTS_PP_THREAD_H_
 #define PPAPI_TESTS_PP_THREAD_H_
 
 #include "ppapi/c/pp_macros.h"
 #include "ppapi/tests/test_utils.h"
@@ skipping 15 matching lines @@
  * Client). Apps that use PPAPI only with Native Client should generally use the
  * Native Client POSIX implementation instead.
  *
  * TODO(dmichael): Move this file to ppapi/c and delete this comment, if we end
  * up needing platform independent threads in PPAPI C or C++. This file was
  * written using inline functions and PPAPI naming conventions with the intent
  * of making it possible to put it in to ppapi/c. Currently, however, it's only
  * used in ppapi/tests, so is not part of the published API.
  */
 
+typedef void (PP_ThreadFunction)(void* data);
+
 #if defined(PPAPI_POSIX)
 typedef pthread_t PP_ThreadType;
 #elif defined(PPAPI_OS_WIN)
-typedef uintptr_t PP_ThreadType;
+struct PP_ThreadType {

[bbudge, 2014/09/05 17:22:59]

Given that this is now a struct, PP_ThreadType doesn't seem like a great name.
How about PP_Thread? I think it's available, though you'd have to change 2 more
files that reference this.

+  HANDLE handle;
+  PP_ThreadFunction* thread_func;
+  void* thread_arg;
+};
 #endif
 
-typedef void (PP_ThreadFunction)(void* data);
-
 PP_INLINE bool PP_CreateThread(PP_ThreadType* thread,
                                PP_ThreadFunction function,
                                void* thread_arg);
 PP_INLINE void PP_JoinThread(PP_ThreadType thread);
 
 #if defined(PPAPI_POSIX)
 /* Because POSIX thread functions return void* and Windows thread functions do
  * not, we make PPAPI thread functions have the least capability (no returns).
  * This struct wraps the user data & function so that we can use the correct
  * function type on POSIX platforms.
@@ skipping 23 matching lines @@
                          PP_POSIXThreadFunctionThunk,
                          arg_wrapper) == 0);
 }
 
 PP_INLINE void PP_JoinThread(PP_ThreadType thread) {
   void* exit_status;
   pthread_join(thread, &exit_status);
 }
 
 #elif defined(PPAPI_OS_WIN)
 typedef DWORD (PP_WindowsThreadFunction)(void* data);

[bbudge, 2014/09/05 17:22:59]

This typedef doesn't appear to be used anywhere.

 
+PP_INLINE unsigned int __stdcall ProxyThreadFunc(void* param) {

[bbudge, 2014/09/05 17:22:59]

This is really an adapter or 'thunk' for the thread function. Could you name it
PP_WindowsThreadFunction? Also, I think the return type should be DWORD or just
unsigned.
http://msdn.microsoft.com/en-us/library/kdzttdcb.aspx

+  PP_ThreadType* params = reinterpret_cast<PP_ThreadType*>(param);
+  params->thread_func(params->thread_arg);
+  return 0;
+}
+
 PP_INLINE bool PP_CreateThread(PP_ThreadType* thread,
                                PP_ThreadFunction function,
                                void* thread_arg) {
   if (!thread)
     return false;
-  *thread = ::_beginthread(function,
-                           0,  /* Use default stack size. */
-                           thread_arg);
-  return (*thread != NULL);
+  thread->thread_func = function;
+  thread->thread_arg = thread_arg;
+  uintptr_t raw_handle = ::_beginthreadex(NULL,
+                                    0,  /* Use default stack size. */

[bbudge, 2014/09/05 17:22:59]

nit: indent is strange

+                                    &ProxyThreadFunc,
+                                    thread,
+                                    0,
+                                    NULL);
+  thread->handle = reinterpret_cast<HANDLE>(raw_handle);
+  return (thread->handle != NULL);
 }
 
-PP_INLINE void PP_JoinThread(PP_ThreadType thread) {
-  ::WaitForSingleObject((HANDLE)thread, INFINITE);
+PP_INLINE void PP_JoinThread(PP_ThreadType thread_info) {
+  ::WaitForSingleObject(thread_info.handle, INFINITE);
+  ::CloseHandle(thread_info.handle);
 }
 
 #endif
 
 
 /**
  * @}
  */
 
 #endif  /* PPAPI_TESTS_PP_THREAD_H_ */