kc3-lang/angle/src/libGLESv2/global_state.cpp

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• Hash : cb286073
  Author :
  Date : 2020-09-20T21:59:24
  

  Use c++ thread_local for current thread.
  
  This solves a race condition using the global context.
  Sadly we can't use an unprotected variable safely because
  it can be written/read from multiple threads doing MakeCurrent.
  
  Has about a 2 ns regression when tested in Linux/Release per
  call. "null" benchmark test went from 27 -> 29 ns/iteration.
  
  Fixes a TSAN warning that popped up in angle_end2end_tests.
  
  Test: DrawCallPerfBenchmark.Run/vulkan_null
  Test: EGLContextASANTest.DestroyContextInUse/ES3_Vulkan
  Bug: b/168744561
  Change-Id: Ic56f3faae81c1087b942a3cfc0e011b9ab439e0f
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2419641
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Commit-Queue: Jamie Madill <jmadill@chromium.org>
  

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• src/libGLESv2/global_state.cpp

• //
  // Copyright 2014 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  // global_state.cpp : Implements functions for querying the thread-local GL and EGL state.
  
  #include "libGLESv2/global_state.h"
  
  #include "common/debug.h"
  #include "common/platform.h"
  #include "common/system_utils.h"
  #include "libGLESv2/resource.h"
  
  #include <atomic>
  
  namespace egl
  {
  namespace
  {
  Debug *g_Debug = nullptr;
  
  ANGLE_REQUIRE_CONSTANT_INIT std::atomic<angle::GlobalMutex *> g_Mutex(nullptr);
  static_assert(std::is_trivially_destructible<decltype(g_Mutex)>::value,
                "global mutex is not trivially destructible");
  
  void SetContextToAndroidOpenGLTLSSlot(gl::Context *value)
  {
  #if defined(ANGLE_PLATFORM_ANDROID)
      if (angle::gUseAndroidOpenGLTlsSlot)
      {
          ANGLE_ANDROID_GET_GL_TLS()[angle::kAndroidOpenGLTlsSlot] = static_cast<void *>(value);
      }
  #endif
  }
  
  Thread *AllocateCurrentThread()
  {
      gCurrentThread = new Thread();
  
      // Initialize fast TLS slot
      SetContextToAndroidOpenGLTLSSlot(nullptr);
      gl::gCurrentValidContext = nullptr;
  
      return gCurrentThread;
  }
  
  void AllocateDebug()
  {
      // All EGL calls use a global lock, this is thread safe
      if (g_Debug == nullptr)
      {
          g_Debug = new Debug();
      }
  }
  
  void AllocateMutex()
  {
      if (g_Mutex == nullptr)
      {
          std::unique_ptr<angle::GlobalMutex> newMutex(new angle::GlobalMutex());
          angle::GlobalMutex *expected = nullptr;
          if (g_Mutex.compare_exchange_strong(expected, newMutex.get()))
          {
              newMutex.release();
          }
      }
  }
  
  }  // anonymous namespace
  
  thread_local Thread *gCurrentThread = nullptr;
  
  angle::GlobalMutex &GetGlobalMutex()
  {
      AllocateMutex();
      return *g_Mutex;
  }
  
  Thread *GetCurrentThread()
  {
      Thread *current = gCurrentThread;
      return (current ? current : AllocateCurrentThread());
  }
  
  Debug *GetDebug()
  {
      AllocateDebug();
      return g_Debug;
  }
  
  void SetContextCurrent(Thread *thread, gl::Context *context)
  {
      ASSERT(gCurrentThread);
      gCurrentThread->setCurrent(context);
      SetContextToAndroidOpenGLTLSSlot(context);
      gl::gCurrentValidContext = context;
  }
  }  // namespace egl
  
  #ifdef ANGLE_PLATFORM_WINDOWS
  namespace egl
  {
  
  namespace
  {
  
  void DeallocateCurrentThread()
  {
      SafeDelete(gCurrentThread);
  }
  
  void DeallocateDebug()
  {
      SafeDelete(g_Debug);
  }
  
  void DeallocateMutex()
  {
      angle::GlobalMutex *mutex = g_Mutex.exchange(nullptr);
      {
          // Wait for the mutex to become released by other threads before deleting.
          std::lock_guard<angle::GlobalMutex> lock(*mutex);
      }
      SafeDelete(mutex);
  }
  
  bool InitializeProcess()
  {
      ASSERT(g_Debug == nullptr);
      AllocateDebug();
      AllocateMutex();
      return AllocateCurrentThread() != nullptr;
  }
  
  void TerminateProcess()
  {
      DeallocateDebug();
      DeallocateMutex();
      DeallocateCurrentThread();
  }
  
  }  // anonymous namespace
  
  }  // namespace egl
  
  namespace
  {
  // The following WaitForDebugger code is based on SwiftShader. See:
  // https://cs.chromium.org/chromium/src/third_party/swiftshader/src/Vulkan/main.cpp
  #    if defined(ANGLE_ENABLE_ASSERTS) && !defined(ANGLE_ENABLE_WINDOWS_UWP)
  INT_PTR CALLBACK DebuggerWaitDialogProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
  {
      RECT rect;
  
      switch (uMsg)
      {
          case WM_INITDIALOG:
              ::GetWindowRect(GetDesktopWindow(), &rect);
              ::SetWindowPos(hwnd, HWND_TOP, rect.right / 2, rect.bottom / 2, 0, 0, SWP_NOSIZE);
              ::SetTimer(hwnd, 1, 100, NULL);
              return TRUE;
          case WM_COMMAND:
              if (LOWORD(wParam) == IDCANCEL)
              {
                  ::EndDialog(hwnd, 0);
              }
              break;
          case WM_TIMER:
              if (angle::IsDebuggerAttached())
              {
                  ::EndDialog(hwnd, 0);
              }
      }
  
      return FALSE;
  }
  
  void WaitForDebugger(HINSTANCE instance)
  {
      if (angle::IsDebuggerAttached())
          return;
  
      HRSRC dialog = ::FindResourceA(instance, MAKEINTRESOURCEA(IDD_DIALOG1), MAKEINTRESOURCEA(5));
      if (!dialog)
      {
          printf("Error finding wait for debugger dialog. Error %lu.\n", ::GetLastError());
          return;
      }
  
      DLGTEMPLATE *dialogTemplate = reinterpret_cast<DLGTEMPLATE *>(::LoadResource(instance, dialog));
      ::DialogBoxIndirectA(instance, dialogTemplate, NULL, DebuggerWaitDialogProc);
  }
  #    else
  void WaitForDebugger(HINSTANCE instance) {}
  #    endif  // defined(ANGLE_ENABLE_ASSERTS) && !defined(ANGLE_ENABLE_WINDOWS_UWP)
  }  // namespace
  
  extern "C" BOOL WINAPI DllMain(HINSTANCE instance, DWORD reason, LPVOID)
  {
      switch (reason)
      {
          case DLL_PROCESS_ATTACH:
              if (angle::GetEnvironmentVar("ANGLE_WAIT_FOR_DEBUGGER") == "1")
              {
                  WaitForDebugger(instance);
              }
              return static_cast<BOOL>(egl::InitializeProcess());
  
          case DLL_THREAD_ATTACH:
              return static_cast<BOOL>(egl::AllocateCurrentThread() != nullptr);
  
          case DLL_THREAD_DETACH:
              egl::DeallocateCurrentThread();
              break;
  
          case DLL_PROCESS_DETACH:
              egl::TerminateProcess();
              break;
      }
  
      return TRUE;
  }
  #endif  // ANGLE_PLATFORM_WINDOWS
  

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