michael@0: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_ATOMIC_SEQUENCE_NUM_H_
michael@0: #define BASE_ATOMIC_SEQUENCE_NUM_H_
michael@0: 
michael@0: #include "base/atomicops.h"
michael@0: #include "base/basictypes.h"
michael@0: 
michael@0: namespace base {
michael@0: 
michael@0: class AtomicSequenceNumber {
michael@0:  public:
michael@0:   AtomicSequenceNumber() : seq_(0) { }
michael@0:   explicit AtomicSequenceNumber(base::LinkerInitialized x) { /* seq_ is 0 */ }
michael@0: 
michael@0:   int GetNext() {
michael@0:     return static_cast<int>(
michael@0:         base::subtle::NoBarrier_AtomicIncrement(&seq_, 1) - 1);
michael@0:   }
michael@0: 
michael@0:  private:
michael@0:   base::subtle::Atomic32 seq_;
michael@0:   DISALLOW_COPY_AND_ASSIGN(AtomicSequenceNumber);
michael@0: };
michael@0: 
michael@0: }  // namespace base
michael@0: 
michael@0: #endif  // BASE_ATOMIC_SEQUENCE_NUM_H_