199 lines
8.8 KiB
C++
199 lines
8.8 KiB
C++
// Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2012
|
|
// Google Inc. All rights reserved.
|
|
//
|
|
// Redistribution and use in source and binary forms, with or without
|
|
// modification, are permitted provided that the following conditions are
|
|
// met:
|
|
//
|
|
// * Redistributions of source code must retain the above copyright
|
|
// notice, this list of conditions and the following disclaimer.
|
|
// * Redistributions in binary form must reproduce the above
|
|
// copyright notice, this list of conditions and the following disclaimer
|
|
// in the documentation and/or other materials provided with the
|
|
// distribution.
|
|
// * Neither the name of Google Inc. nor the name Chromium Embedded
|
|
// Framework nor the names of its contributors may be used to endorse
|
|
// or promote products derived from this software without specific prior
|
|
// written permission.
|
|
//
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
// For atomic operations on reference counts, see cef_atomic_ref_count.h.
|
|
|
|
// The routines exported by this module are subtle. If you use them, even if
|
|
// you get the code right, it will depend on careful reasoning about atomicity
|
|
// and memory ordering; it will be less readable, and harder to maintain. If
|
|
// you plan to use these routines, you should have a good reason, such as solid
|
|
// evidence that performance would otherwise suffer, or there being no
|
|
// alternative. You should assume only properties explicitly guaranteed by the
|
|
// specifications in this file. You are almost certainly _not_ writing code
|
|
// just for the x86; if you assume x86 semantics, x86 hardware bugs and
|
|
// implementations on other archtectures will cause your code to break. If you
|
|
// do not know what you are doing, avoid these routines, and use a Mutex.
|
|
//
|
|
// It is incorrect to make direct assignments to/from an atomic variable.
|
|
// You should use one of the Load or Store routines. The NoBarrier
|
|
// versions are provided when no barriers are needed:
|
|
// NoBarrier_Store()
|
|
// NoBarrier_Load()
|
|
// Although there are currently no compiler enforcement, you are encouraged
|
|
// to use these.
|
|
//
|
|
|
|
#ifndef CEF_INCLUDE_BASE_CEF_ATOMICOPS_H_
|
|
#define CEF_INCLUDE_BASE_CEF_ATOMICOPS_H_
|
|
#pragma once
|
|
|
|
#if defined(BASE_ATOMICOPS_H_)
|
|
// Do nothing if the Chromium header has already been included.
|
|
// This can happen in cases where Chromium code is used directly by the
|
|
// client application. When using Chromium code directly always include
|
|
// the Chromium header first to avoid type conflicts.
|
|
#elif defined(BUILDING_CEF_SHARED)
|
|
// When building CEF include the Chromium header directly.
|
|
#include "base/atomicops.h"
|
|
#else // !BUILDING_CEF_SHARED
|
|
// The following is substantially similar to the Chromium implementation.
|
|
// If the Chromium implementation diverges the below implementation should be
|
|
// updated to match.
|
|
|
|
#include <stdint.h>
|
|
|
|
#include "include/base/cef_build.h"
|
|
|
|
#if defined(OS_WIN) && defined(ARCH_CPU_64_BITS)
|
|
// windows.h #defines this (only on x64). This causes problems because the
|
|
// public API also uses MemoryBarrier at the public name for this fence. So, on
|
|
// X64, undef it, and call its documented
|
|
// (http://msdn.microsoft.com/en-us/library/windows/desktop/ms684208.aspx)
|
|
// implementation directly.
|
|
#undef MemoryBarrier
|
|
#endif
|
|
|
|
namespace base {
|
|
namespace subtle {
|
|
|
|
typedef int32_t Atomic32;
|
|
#ifdef ARCH_CPU_64_BITS
|
|
// We need to be able to go between Atomic64 and AtomicWord implicitly. This
|
|
// means Atomic64 and AtomicWord should be the same type on 64-bit.
|
|
#if defined(__ILP32__) || defined(OS_NACL)
|
|
// NaCl's intptr_t is not actually 64-bits on 64-bit!
|
|
// http://code.google.com/p/nativeclient/issues/detail?id=1162
|
|
typedef int64_t Atomic64;
|
|
#else
|
|
typedef intptr_t Atomic64;
|
|
#endif
|
|
#endif
|
|
|
|
// Use AtomicWord for a machine-sized pointer. It will use the Atomic32 or
|
|
// Atomic64 routines below, depending on your architecture.
|
|
typedef intptr_t AtomicWord;
|
|
|
|
// Atomically execute:
|
|
// result = *ptr;
|
|
// if (*ptr == old_value)
|
|
// *ptr = new_value;
|
|
// return result;
|
|
//
|
|
// I.e., replace "*ptr" with "new_value" if "*ptr" used to be "old_value".
|
|
// Always return the old value of "*ptr"
|
|
//
|
|
// This routine implies no memory barriers.
|
|
Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
|
|
Atomic32 old_value,
|
|
Atomic32 new_value);
|
|
|
|
// Atomically store new_value into *ptr, returning the previous value held in
|
|
// *ptr. This routine implies no memory barriers.
|
|
Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr, Atomic32 new_value);
|
|
|
|
// Atomically increment *ptr by "increment". Returns the new value of
|
|
// *ptr with the increment applied. This routine implies no memory barriers.
|
|
Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr, Atomic32 increment);
|
|
|
|
Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
|
|
Atomic32 increment);
|
|
|
|
// These following lower-level operations are typically useful only to people
|
|
// implementing higher-level synchronization operations like spinlocks,
|
|
// mutexes, and condition-variables. They combine CompareAndSwap(), a load, or
|
|
// a store with appropriate memory-ordering instructions. "Acquire" operations
|
|
// ensure that no later memory access can be reordered ahead of the operation.
|
|
// "Release" operations ensure that no previous memory access can be reordered
|
|
// after the operation. "Barrier" operations have both "Acquire" and "Release"
|
|
// semantics. A MemoryBarrier() has "Barrier" semantics, but does no memory
|
|
// access.
|
|
Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
|
|
Atomic32 old_value,
|
|
Atomic32 new_value);
|
|
Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
|
|
Atomic32 old_value,
|
|
Atomic32 new_value);
|
|
|
|
void MemoryBarrier();
|
|
void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value);
|
|
void Acquire_Store(volatile Atomic32* ptr, Atomic32 value);
|
|
void Release_Store(volatile Atomic32* ptr, Atomic32 value);
|
|
|
|
Atomic32 NoBarrier_Load(volatile const Atomic32* ptr);
|
|
Atomic32 Acquire_Load(volatile const Atomic32* ptr);
|
|
Atomic32 Release_Load(volatile const Atomic32* ptr);
|
|
|
|
// 64-bit atomic operations (only available on 64-bit processors).
|
|
#ifdef ARCH_CPU_64_BITS
|
|
Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
|
|
Atomic64 old_value,
|
|
Atomic64 new_value);
|
|
Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr, Atomic64 new_value);
|
|
Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment);
|
|
Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment);
|
|
|
|
Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
|
|
Atomic64 old_value,
|
|
Atomic64 new_value);
|
|
Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
|
|
Atomic64 old_value,
|
|
Atomic64 new_value);
|
|
void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value);
|
|
void Acquire_Store(volatile Atomic64* ptr, Atomic64 value);
|
|
void Release_Store(volatile Atomic64* ptr, Atomic64 value);
|
|
Atomic64 NoBarrier_Load(volatile const Atomic64* ptr);
|
|
Atomic64 Acquire_Load(volatile const Atomic64* ptr);
|
|
Atomic64 Release_Load(volatile const Atomic64* ptr);
|
|
#endif // ARCH_CPU_64_BITS
|
|
|
|
} // namespace subtle
|
|
} // namespace base
|
|
|
|
// Include our platform specific implementation.
|
|
#if defined(OS_WIN) && defined(COMPILER_MSVC) && defined(ARCH_CPU_X86_FAMILY)
|
|
#include "include/base/internal/cef_atomicops_x86_msvc.h"
|
|
#elif defined(OS_MACOSX)
|
|
#include "include/base/internal/cef_atomicops_mac.h"
|
|
#elif defined(COMPILER_GCC) && defined(ARCH_CPU_X86_FAMILY)
|
|
#include "include/base/internal/cef_atomicops_x86_gcc.h"
|
|
#else
|
|
#error "Atomic operations are not supported on your platform"
|
|
#endif
|
|
|
|
// On some platforms we need additional declarations to make
|
|
// AtomicWord compatible with our other Atomic* types.
|
|
#if defined(OS_MACOSX) || defined(OS_OPENBSD)
|
|
#include "include/base/internal/cef_atomicops_atomicword_compat.h"
|
|
#endif
|
|
|
|
#endif // !BUILDING_CEF_SHARED
|
|
|
|
#endif // CEF_INCLUDE_BASE_CEF_ATOMICOPS_H_
|