kc3-lang/angle/src/common/tls.cpp

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• Author : Jamie Madill
  Date : 2020-09-20 21:59:24
  Hash : cb286073
  Message : 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>

• src/common/tls.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.
  //
  
  // tls.cpp: Simple cross-platform interface for thread local storage.
  
  #include "common/tls.h"
  
  #include "common/debug.h"
  
  #ifdef ANGLE_ENABLE_WINDOWS_UWP
  #    include <map>
  #    include <mutex>
  #    include <set>
  #    include <vector>
  
  #    include <Windows.System.Threading.h>
  #    include <wrl/async.h>
  #    include <wrl/client.h>
  
  using namespace std;
  using namespace Windows::Foundation;
  using namespace ABI::Windows::System::Threading;
  
  // Thread local storage for Windows Store support
  typedef vector<void *> ThreadLocalData;
  
  static __declspec(thread) ThreadLocalData *currentThreadData = nullptr;
  static set<ThreadLocalData *> allThreadData;
  static DWORD nextTlsIndex = 0;
  static vector<DWORD> freeTlsIndices;
  
  #endif
  
  bool gUseAndroidOpenGLTlsSlot = false;
  
  TLSIndex CreateTLSIndex()
  {
      TLSIndex index;
  
  #ifdef ANGLE_PLATFORM_WINDOWS
  #    ifdef ANGLE_ENABLE_WINDOWS_UWP
      if (!freeTlsIndices.empty())
      {
          DWORD result = freeTlsIndices.back();
          freeTlsIndices.pop_back();
          index = result;
      }
      else
      {
          index = nextTlsIndex++;
      }
  #    else
      index = TlsAlloc();
  #    endif
  
  #elif defined(ANGLE_PLATFORM_POSIX)
      // Create global pool key
      if ((pthread_key_create(&index, nullptr)) != 0)
      {
          index = TLS_INVALID_INDEX;
      }
  #endif
  
      ASSERT(index != TLS_INVALID_INDEX &&
             "CreateTLSIndex(): Unable to allocate Thread Local Storage");
      return index;
  }
  
  bool DestroyTLSIndex(TLSIndex index)
  {
      ASSERT(index != TLS_INVALID_INDEX && "DestroyTLSIndex(): Invalid TLS Index");
      if (index == TLS_INVALID_INDEX)
      {
          return false;
      }
  
  #ifdef ANGLE_PLATFORM_WINDOWS
  #    ifdef ANGLE_ENABLE_WINDOWS_UWP
      ASSERT(index < nextTlsIndex);
      ASSERT(find(freeTlsIndices.begin(), freeTlsIndices.end(), index) == freeTlsIndices.end());
  
      freeTlsIndices.push_back(index);
      for (auto threadData : allThreadData)
      {
          if (threadData->size() > index)
          {
              threadData->at(index) = nullptr;
          }
      }
      return true;
  #    else
      return (TlsFree(index) == TRUE);
  #    endif
  #elif defined(ANGLE_PLATFORM_POSIX)
      return (pthread_key_delete(index) == 0);
  #endif
  }
  
  bool SetTLSValue(TLSIndex index, void *value)
  {
      ASSERT(index != TLS_INVALID_INDEX && "SetTLSValue(): Invalid TLS Index");
      if (index == TLS_INVALID_INDEX)
      {
          return false;
      }
  
  #ifdef ANGLE_PLATFORM_WINDOWS
  #    ifdef ANGLE_ENABLE_WINDOWS_UWP
      ThreadLocalData *threadData = currentThreadData;
      if (!threadData)
      {
          threadData = new ThreadLocalData(index + 1, nullptr);
          allThreadData.insert(threadData);
          currentThreadData = threadData;
      }
      else if (threadData->size() <= index)
      {
          threadData->resize(index + 1, nullptr);
      }
  
      threadData->at(index) = value;
      return true;
  #    else
      return (TlsSetValue(index, value) == TRUE);
  #    endif
  #elif defined(ANGLE_PLATFORM_POSIX)
      return (pthread_setspecific(index, value) == 0);
  #endif
  }
  
  void *GetTLSValue(TLSIndex index)
  {
      ASSERT(index != TLS_INVALID_INDEX && "GetTLSValue(): Invalid TLS Index");
      if (index == TLS_INVALID_INDEX)
      {
          return nullptr;
      }
  
  #ifdef ANGLE_PLATFORM_WINDOWS
  #    ifdef ANGLE_ENABLE_WINDOWS_UWP
      ThreadLocalData *threadData = currentThreadData;
      if (threadData && threadData->size() > index)
      {
          return threadData->at(index);
      }
      else
      {
          return nullptr;
      }
  #    else
      return TlsGetValue(index);
  #    endif
  #elif defined(ANGLE_PLATFORM_POSIX)
      return pthread_getspecific(index);
  #endif
  }