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

• Show log

  Commit

• Hash : d9d583bf
  Author :
  Date : 2024-04-15T00:24:47
  

  Implement a lock/unlock-only mutex based on futex
  
  Pthread mutexes are expensive due to their numerous features.  When a
  mutex only needs to support lock and unlock, its implementation can be
  much simpler.  The implementation in this change is "inspired" by a
  similar mutex in mesa.
  
  Expected uses of this mutex are:
  
  - Allowing some OpenGL calls to avoid the share group lock and instead
    lock the specific shared object they operate on.
  - Replacing SpinLock in the OpenCL implementation (spin-lock in user
    space is a bad idea [1])
  - Generally anywhere we use std::mutex just to do lock/unlock
  
  Tests based on patch authored by Igor Nazarov <i.nazarov@samsung.com>
  
  [1]:https://www.realworldtech.com/forum/?threadid=189711&curpostid=189723
  
  Bug: angleproject:8667
  Change-Id: I52278c9d19616338c499bbcef6684746caead6ca
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5446558
  Reviewed-by: Roman Lavrov <romanl@google.com>
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  

Download

• src/common/SimpleMutex.cpp

• //
  // Copyright 2024 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.
  //
  // SimpleMutex.cpp:
  //   Implementation of SimpleMutex.h.
  
  #include "common/SimpleMutex.h"
  
  #if ANGLE_USE_FUTEX
  
  #    include <limits.h>
  #    include <stdint.h>
  
  #    if defined(ANGLE_PLATFORM_LINUX) || defined(ANGLE_PLATFORM_ANDROID)
  #        include <linux/futex.h>
  #        include <sys/syscall.h>
  #        include <unistd.h>
  #    endif  // defined(ANGLE_PLATFORM_LINUX) || defined(ANGLE_PLATFORM_ANDROID)
  
  #    if defined(ANGLE_PLATFORM_WINDOWS)
  #        include <errno.h>
  #        include <windows.h>
  #    endif  // defined(ANGLE_PLATFORM_WINDOWS)
  
  namespace angle
  {
  namespace priv
  {
  #    if defined(ANGLE_PLATFORM_LINUX) || defined(ANGLE_PLATFORM_ANDROID)
  namespace
  {
  ANGLE_INLINE void SysFutex(void *addr, int op, int val, int val3)
  {
      syscall(SYS_futex, addr, op, val, nullptr, nullptr, val3);
  }
  }  // anonymous namespace
  
  void MutexOnFutex::futexWait()
  {
      SysFutex(&mState, FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG, kBlocked, FUTEX_BITSET_MATCH_ANY);
  }
  void MutexOnFutex::futexWake()
  {
      SysFutex(&mState, FUTEX_WAKE | FUTEX_PRIVATE_FLAG, kLocked, 0);
  }
  #    endif  // defined(ANGLE_PLATFORM_LINUX) || defined(ANGLE_PLATFORM_ANDROID)
  
  #    if defined(ANGLE_PLATFORM_WINDOWS)
  void MutexOnFutex::futexWait()
  {
      int value = kBlocked;
      WaitOnAddress(&mState, &value, sizeof(value), INFINITE);
  }
  
  void MutexOnFutex::futexWake()
  {
      WakeByAddressSingle(&mState);
  }
  #    endif  // defined(ANGLE_PLATFORM_WINDOWS)
  }  // namespace priv
  }  // namespace angle
  
  #endif  // ANGLE_USE_FUTEX
  

Download