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| 1 /* | 1 /* |
| 2 * Copyright 2011 The WebRTC Project Authors. All rights reserved. | 2 * Copyright 2011 The WebRTC Project Authors. All rights reserved. |
| 3 * | 3 * |
| 4 * Use of this source code is governed by a BSD-style license | 4 * Use of this source code is governed by a BSD-style license |
| 5 * that can be found in the LICENSE file in the root of the source | 5 * that can be found in the LICENSE file in the root of the source |
| 6 * tree. An additional intellectual property rights grant can be found | 6 * tree. An additional intellectual property rights grant can be found |
| 7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
| 8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
| 9 */ | 9 */ |
| 10 | 10 |
| 11 #ifndef WEBRTC_BASE_ATOMICOPS_H_ | 11 #ifndef WEBRTC_BASE_ATOMICOPS_H_ |
| 12 #define WEBRTC_BASE_ATOMICOPS_H_ | 12 #define WEBRTC_BASE_ATOMICOPS_H_ |
| 13 | 13 |
| 14 #if defined(WEBRTC_WIN) | 14 #if defined(WEBRTC_WIN) |
| 15 // Include winsock2.h before including <windows.h> to maintain consistency with | 15 // Include winsock2.h before including <windows.h> to maintain consistency with |
| 16 // win32.h. We can't include win32.h directly here since it pulls in | 16 // win32.h. We can't include win32.h directly here since it pulls in |
| 17 // headers such as basictypes.h which causes problems in Chromium where webrtc | 17 // headers such as basictypes.h which causes problems in Chromium where webrtc |
| 18 // exists as two separate projects, webrtc and libjingle. | 18 // exists as two separate projects, webrtc and libjingle. |
| 19 #include <winsock2.h> | 19 #include <winsock2.h> |
| 20 #include <windows.h> | 20 #include <windows.h> |
| 21 #endif // defined(WEBRTC_WIN) | 21 #endif // defined(WEBRTC_WIN) |
| 22 | 22 |
| 23 namespace rtc { | 23 namespace rtc { |
| 24 | |
| 25 class AtomicOps { | 24 class AtomicOps { |
| 26 public: | 25 public: |
| 27 #if defined(WEBRTC_WIN) | 26 #if defined(WEBRTC_WIN) |
| 28 // Assumes sizeof(int) == sizeof(LONG), which it is on Win32 and Win64. | 27 // Assumes sizeof(int) == sizeof(LONG), which it is on Win32 and Win64. |
| 29 static int Increment(volatile int* i) { | 28 static int Increment(volatile int* i) { |
| 30 return ::InterlockedIncrement(reinterpret_cast<volatile LONG*>(i)); | 29 return ::InterlockedIncrement(reinterpret_cast<volatile LONG*>(i)); |
| 31 } | 30 } |
| 32 static int Decrement(volatile int* i) { | 31 static int Decrement(volatile int* i) { |
| 33 return ::InterlockedDecrement(reinterpret_cast<volatile LONG*>(i)); | 32 return ::InterlockedDecrement(reinterpret_cast<volatile LONG*>(i)); |
| 34 } | 33 } |
| (...skipping 20 matching lines...) Expand all Loading... | |
| 55 } | 54 } |
| 56 static void ReleaseStore(volatile int* i, int value) { | 55 static void ReleaseStore(volatile int* i, int value) { |
| 57 __atomic_store_n(i, value, __ATOMIC_RELEASE); | 56 __atomic_store_n(i, value, __ATOMIC_RELEASE); |
| 58 } | 57 } |
| 59 static int CompareAndSwap(volatile int* i, int old_value, int new_value) { | 58 static int CompareAndSwap(volatile int* i, int old_value, int new_value) { |
| 60 return __sync_val_compare_and_swap(i, old_value, new_value); | 59 return __sync_val_compare_and_swap(i, old_value, new_value); |
| 61 } | 60 } |
| 62 #endif | 61 #endif |
| 63 }; | 62 }; |
| 64 | 63 |
| 65 // POD struct version of AtomicOps, prevents accidental non-atomic operator | |
| 66 // usage (such as ++, -- or =). Functions are static, so that the AtomicInt:: | |
| 67 // prefix must be present in the code, clearly labeling the operations as | |
| 68 // atomic. | |
| 69 // Do not copy-initialize, since that performs non-atomic reads of value_. The | |
| 70 // copy constructor needs to be present for brace initialization. | |
| 71 struct AtomicInt { | |
| 72 AtomicInt() = delete; | |
|
pbos-webrtc
2015/12/07 22:33:35
Might be relandable without constructors removed (
| |
| 73 // TODO(pbos): When MSVC allows brace initialization (or we move to | |
| 74 // std::atomic), remove copy constructor (or have it implicitly removed by | |
| 75 // std::atomic). | |
| 76 void operator=(const AtomicInt&) = delete; | |
| 77 | 64 |
| 78 // value_ is public to permit brace initialization. Should not be accessed | |
| 79 // directly. | |
| 80 volatile int value_; | |
| 81 | 65 |
| 82 // Atomically increments |i|, returns the resulting incremented value. | |
| 83 static int Increment(AtomicInt* i) { | |
| 84 return AtomicOps::Increment(&i->value_); | |
| 85 } | |
| 86 | |
| 87 // Atomically decrements |i|, returns the resulting decremented value. | |
| 88 static int Decrement(AtomicInt* i) { | |
| 89 return AtomicOps::Decrement(&i->value_); | |
| 90 } | |
| 91 | |
| 92 // Atomically loads |i|. | |
| 93 static int AcquireLoad(const AtomicInt* i) { | |
| 94 return AtomicOps::AcquireLoad(&i->value_); | |
| 95 } | |
| 96 | |
| 97 // Atomically stores |value| in |i|. | |
| 98 static void ReleaseStore(AtomicInt* i, int value) { | |
| 99 AtomicOps::ReleaseStore(&i->value_, value); | |
| 100 } | |
| 101 | |
| 102 // Attempts to compare-and-swaps |old_value| for |new_value| in |i| , returns | |
| 103 // |i|'s initial value. If equal to |old_value|, then the CAS succeeded, | |
| 104 // otherwise no operation is performed. | |
| 105 static int CompareAndSwap(AtomicInt* i, int old_value, int new_value) { | |
| 106 return AtomicOps::CompareAndSwap(&i->value_, old_value, new_value); | |
| 107 } | |
| 108 }; | |
| 109 } | 66 } |
| 110 | 67 |
| 111 #endif // WEBRTC_BASE_ATOMICOPS_H_ | 68 #endif // WEBRTC_BASE_ATOMICOPS_H_ |
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