kc3-lang/SDL/src/thread/stdcpp/SDL_sysmutex.cpp

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• Hash : d59caffe
  Author :
  Date : 2022-12-13T14:03:40
  

  Added support for clang thread-safety analysis
  
  The annotations have been added to SDL_mutex.h and have been made public so applications can enable this for their own code.
  
  Clang assumes that locking and unlocking can't fail, but SDL has the concept of a NULL mutex, so the mutex functions have been changed not to report errors if a mutex hasn't been initialized. We do have mutexes that might be accessed when they are NULL, notably in the event system, so this is an important change.
  
  This commit cleans up a bunch of rare race conditions in the joystick and game controller code so now everything should be completely protected by the joystick lock.
  
  To test this, change the compiler to "clang -Wthread-safety -Werror=thread-safety -DSDL_THREAD_SAFETY_ANALYSIS"
  

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• src/thread/stdcpp/SDL_sysmutex.cpp

• /*
    Simple DirectMedia Layer
    Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
  
    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any damages
    arising from the use of this software.
  
    Permission is granted to anyone to use this software for any purpose,
    including commercial applications, and to alter it and redistribute it
    freely, subject to the following restrictions:
  
    1. The origin of this software must not be misrepresented; you must not
       claim that you wrote the original software. If you use this software
       in a product, an acknowledgment in the product documentation would be
       appreciated but is not required.
    2. Altered source versions must be plainly marked as such, and must not be
       misrepresented as being the original software.
    3. This notice may not be removed or altered from any source distribution.
  */
  #include "../../SDL_internal.h"
  
  extern "C" {
  #include "SDL_thread.h"
  #include "SDL_systhread_c.h"
  }
  
  #include <system_error>
  
  #include "SDL_sysmutex_c.h"
  #include <Windows.h>
  
  /* Create a mutex */
  extern "C" SDL_mutex *
  SDL_CreateMutex(void)
  {
      /* Allocate and initialize the mutex */
      try {
          SDL_mutex *mutex = new SDL_mutex;
          return mutex;
      } catch (std::system_error &ex) {
          SDL_SetError("unable to create a C++ mutex: code=%d; %s", ex.code(), ex.what());
          return NULL;
      } catch (std::bad_alloc &) {
          SDL_OutOfMemory();
          return NULL;
      }
  }
  
  /* Free the mutex */
  extern "C" void
  SDL_DestroyMutex(SDL_mutex *mutex)
  {
      if (mutex != NULL) {
          delete mutex;
      }
  }
  
  /* Lock the mutex */
  extern "C" int
  SDL_LockMutex(SDL_mutex *mutex) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
  {
      if (mutex == NULL) {
          return 0;
      }
  
      try {
          mutex->cpp_mutex.lock();
          return 0;
      } catch (std::system_error &ex) {
          return SDL_SetError("unable to lock a C++ mutex: code=%d; %s", ex.code(), ex.what());
      }
  }
  
  /* TryLock the mutex */
  int SDL_TryLockMutex(SDL_mutex *mutex)
  {
      int retval = 0;
  
      if (mutex == NULL) {
          return 0;
      }
  
      if (mutex->cpp_mutex.try_lock() == false) {
          retval = SDL_MUTEX_TIMEDOUT;
      }
      return retval;
  }
  
  /* Unlock the mutex */
  extern "C" int
  SDL_UnlockMutex(SDL_mutex *mutex) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
  {
      if (mutex == NULL) {
          return 0;
      }
  
      mutex->cpp_mutex.unlock();
      return 0;
  }
  
  /* vi: set ts=4 sw=4 expandtab: */
  

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