235c35f292
Using explicit atomic operations permits TSan to understand them and prevents false positives. Downgrading the atomic Load to acquire semantics. This reduces the number of memory barriers inserted from two down to one at most. Also renaming Load/Store to AcquireLoad/ReleaseStore. BUG=chromium:512382 R=dvyukov@chromium.org, glider@chromium.org TBR=tommi@webrtc.org Review URL: https://codereview.webrtc.org/1246073002 Cr-Commit-Position: refs/heads/master@{#9613}
69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
/*
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* Copyright 2011 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_BASE_ATOMICOPS_H_
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#define WEBRTC_BASE_ATOMICOPS_H_
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#if defined(WEBRTC_WIN)
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// Include winsock2.h before including <windows.h> to maintain consistency with
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// win32.h. We can't include win32.h directly here since it pulls in
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// headers such as basictypes.h which causes problems in Chromium where webrtc
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// exists as two separate projects, webrtc and libjingle.
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#include <winsock2.h>
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#include <windows.h>
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#endif // defined(WEBRTC_WIN)
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namespace rtc {
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class AtomicOps {
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public:
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#if defined(WEBRTC_WIN)
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// Assumes sizeof(int) == sizeof(LONG), which it is on Win32 and Win64.
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static int Increment(volatile int* i) {
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return ::InterlockedIncrement(reinterpret_cast<volatile LONG*>(i));
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}
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static int Decrement(volatile int* i) {
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return ::InterlockedDecrement(reinterpret_cast<volatile LONG*>(i));
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}
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static int AcquireLoad(volatile const int* i) {
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return *i;
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}
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static void ReleaseStore(volatile int* i, int value) {
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*i = value;
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}
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static int CompareAndSwap(volatile int* i, int old_value, int new_value) {
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return ::InterlockedCompareExchange(reinterpret_cast<volatile LONG*>(i),
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new_value,
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old_value);
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}
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#else
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static int Increment(volatile int* i) {
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return __sync_add_and_fetch(i, 1);
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}
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static int Decrement(volatile int* i) {
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return __sync_sub_and_fetch(i, 1);
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}
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static int AcquireLoad(volatile const int* i) {
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return __atomic_load_n(i, __ATOMIC_ACQUIRE);
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}
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static void ReleaseStore(volatile int* i, int value) {
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__atomic_store_n(i, value, __ATOMIC_RELEASE);
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}
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static int CompareAndSwap(volatile int* i, int old_value, int new_value) {
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return __sync_val_compare_and_swap(i, old_value, new_value);
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}
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#endif
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};
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}
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#endif // WEBRTC_BASE_ATOMICOPS_H_
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