security/sandbox/chromium/base/atomic_sequence_num.h@6474c204b198 (annotated)
security/sandbox/chromium/base/atomic_sequence_num.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| michael@0 | 2 | // Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 3 | // found in the LICENSE file. |
| michael@0 | 4 | |
| michael@0 | 5 | #ifndef BASE_ATOMIC_SEQUENCE_NUM_H_ |
| michael@0 | 6 | #define BASE_ATOMIC_SEQUENCE_NUM_H_ |
| michael@0 | 7 | |
| michael@0 | 8 | #include "base/atomicops.h" |
| michael@0 | 9 | #include "base/basictypes.h" |
| michael@0 | 10 | |
| michael@0 | 11 | namespace base { |
| michael@0 | 12 | |
| michael@0 | 13 | class AtomicSequenceNumber; |
| michael@0 | 14 | |
| michael@0 | 15 | // Static (POD) AtomicSequenceNumber that MUST be used in global scope (or |
| michael@0 | 16 | // non-function scope) ONLY. This implementation does not generate any static |
| michael@0 | 17 | // initializer. Note that it does not implement any constructor which means |
| michael@0 | 18 | // that its fields are not initialized except when it is stored in the global |
| michael@0 | 19 | // data section (.data in ELF). If you want to allocate an atomic sequence |
| michael@0 | 20 | // number on the stack (or heap), please use the AtomicSequenceNumber class |
| michael@0 | 21 | // declared below. |
| michael@0 | 22 | class StaticAtomicSequenceNumber { |
| michael@0 | 23 | public: |
| michael@0 | 24 | inline int GetNext() { |
| michael@0 | 25 | return static_cast<int>( |
| michael@0 | 26 | base::subtle::NoBarrier_AtomicIncrement(&seq_, 1) - 1); |
| michael@0 | 27 | } |
| michael@0 | 28 | |
| michael@0 | 29 | private: |
| michael@0 | 30 | friend class AtomicSequenceNumber; |
| michael@0 | 31 | |
| michael@0 | 32 | inline void Reset() { |
| michael@0 | 33 | base::subtle::Release_Store(&seq_, 0); |
| michael@0 | 34 | } |
| michael@0 | 35 | |
| michael@0 | 36 | base::subtle::Atomic32 seq_; |
| michael@0 | 37 | }; |
| michael@0 | 38 | |
| michael@0 | 39 | // AtomicSequenceNumber that can be stored and used safely (i.e. its fields are |
| michael@0 | 40 | // always initialized as opposed to StaticAtomicSequenceNumber declared above). |
| michael@0 | 41 | // Please use StaticAtomicSequenceNumber if you want to declare an atomic |
| michael@0 | 42 | // sequence number in the global scope. |
| michael@0 | 43 | class AtomicSequenceNumber { |
| michael@0 | 44 | public: |
| michael@0 | 45 | AtomicSequenceNumber() { |
| michael@0 | 46 | seq_.Reset(); |
| michael@0 | 47 | } |
| michael@0 | 48 | |
| michael@0 | 49 | inline int GetNext() { |
| michael@0 | 50 | return seq_.GetNext(); |
| michael@0 | 51 | } |
| michael@0 | 52 | |
| michael@0 | 53 | private: |
| michael@0 | 54 | StaticAtomicSequenceNumber seq_; |
| michael@0 | 55 | DISALLOW_COPY_AND_ASSIGN(AtomicSequenceNumber); |
| michael@0 | 56 | }; |
| michael@0 | 57 | |
| michael@0 | 58 | } // namespace base |
| michael@0 | 59 | |
| michael@0 | 60 | #endif // BASE_ATOMIC_SEQUENCE_NUM_H_ |
