kc3-lang/angle/src/libANGLE/GlobalMutex.h

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• Hash : e5619a5c
  Author :
  Date : 2024-10-15T18:27:00
  

  Use EGL sync global lock for all EGL*sync entrypoint calls
  
  To free EGL sync operations from waiting for other EGL calls
  to finish, we use a separate global lock for EGL*sync entrypoints.
  Below angle::SimpleMutex are added to protect resources that may
  have race condition due to being accessed by EGL*sync calls
  and non EGL*sync calls at the same time:
  
  1. Display::mContextMapMutex that protects Display::mState.contextMap
  
  2. static angle::base::NoDestructor<angle::SimpleMutex>
  anglePlatformDisplayMapMutex that protects static
  angle::base::NoDestructor<ANGLEPlatformDisplayMap> displays
  
  3. static angle::base::NoDestructor<angle::SimpleMutex>
  devicePlatformDisplayMapMutex that protects static
  angle::base::NoDestructor<DevicePlatformDisplayMap> displays
  
  EGL_Terminate() entry point takes both global lock and
  global egl sync lock. This is to protect Display::mSyncMap,
  Display::mSyncPools, and Display::mSyncHandleAllocator being
  get cleared by thread 1 calling eglTerminate, while they are
  still accessed by thread 2 through a call such as eglCreateSync.
  So that we won't have thread 2 finish validating the sync object with
  syncID exists in Display::mSyncMap, but then find the
  mSyncMap.find(syncID) returns a nullptr due to the mSyncMap
  is cleared by thread 1. Same applies to EGL_LabelObjectKHR(),
  EGL_ReleaseThread(), ThreadCleanupCallback().
  
  EGL_Initialize() writes to Display::mInitialized. This is read
  by EGL Sync API validation functions. EGL_Initialize() also takes
  both global lock and global sync lock to prevent race conditions
  between EGL_Initialize() and EGL Sync APIs.
  
  When ANGLE_CAPTURE_ENABLED is enabled, fall back to global lock,
  as the CaptureEGLCallToFrameCapture() touches many resources
  (e.g. mMaxAccessedResourceIDs, mFrameCalls)
  that could lead to race conditions without a global lock.
  
  Bug: b/362604439
  Change-Id: Ic0d54a4cd66743bcd0f48f41f247dd223cff2f5e
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5933570
  Reviewed-by: Roman Lavrov <romanl@google.com>
  Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
  Reviewed-by: Igor Nazarov <i.nazarov@samsung.com>
  Commit-Queue: Yuxin Hu <yuxinhu@google.com>
  

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• src/libANGLE/GlobalMutex.h

• //
  // Copyright 2023 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.
  //
  // GlobalMutex.h: Defines Global Mutex and utilities.
  
  #ifndef LIBANGLE_GLOBAL_MUTEX_H_
  #define LIBANGLE_GLOBAL_MUTEX_H_
  
  #include "common/angleutils.h"
  
  namespace egl
  {
  namespace priv
  {
  class GlobalMutex;
  
  enum class GlobalMutexChoice
  {
      // All EGL entry points except EGL Sync objects
      EGL,
      // Entry points relating to EGL Sync objects
      Sync,
  };
  
  template <GlobalMutexChoice mutexChoice>
  class [[nodiscard]] ScopedGlobalMutexLock final : angle::NonCopyable
  {
    public:
      ScopedGlobalMutexLock();
      ~ScopedGlobalMutexLock();
  
  #if !defined(ANGLE_ENABLE_GLOBAL_MUTEX_LOAD_TIME_ALLOCATE)
    private:
      GlobalMutex *mMutex;
  #endif
  };
  }  // namespace priv
  
  using ScopedGlobalEGLMutexLock = priv::ScopedGlobalMutexLock<priv::GlobalMutexChoice::EGL>;
  using ScopedGlobalEGLSyncObjectMutexLock =
      priv::ScopedGlobalMutexLock<priv::GlobalMutexChoice::Sync>;
  
  // For Context protection where lock is optional. Works slower than ScopedGlobalMutexLock.
  class [[nodiscard]] ScopedOptionalGlobalMutexLock final : angle::NonCopyable
  {
    public:
      explicit ScopedOptionalGlobalMutexLock(bool enabled);
      ~ScopedOptionalGlobalMutexLock();
  
    private:
      priv::GlobalMutex *mMutex;
  };
  
  #if defined(ANGLE_PLATFORM_WINDOWS) && !defined(ANGLE_STATIC)
  void AllocateGlobalMutex();
  void DeallocateGlobalMutex();
  #endif
  
  }  // namespace egl
  
  #endif  // LIBANGLE_GLOBAL_MUTEX_H_
  

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