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// Copyright (c) 2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/lazy_instance.h"
#include "base/at_exit.h"
#include "base/atomicops.h"
#include "base/basictypes.h"
#include "base/platform_thread.h"
namespace base {
void LazyInstanceHelper::EnsureInstance(void* instance,
void (*ctor)(void*),
void (*dtor)(void*)) {
// Try to create the instance, if we're the first, will go from EMPTY
// to CREATING, otherwise we've already been beaten here.
if (base::subtle::Acquire_CompareAndSwap(
&state_, STATE_EMPTY, STATE_CREATING) == STATE_EMPTY) {
// Created the instance in the space provided by |instance|.
ctor(instance);
// Instance is created, go from CREATING to CREATED.
base::subtle::Release_Store(&state_, STATE_CREATED);
// Register the destructor callback with AtExitManager.
base::AtExitManager::RegisterCallback(dtor, instance);
} else {
// It's either in the process of being created, or already created. Spin.
while (base::subtle::NoBarrier_Load(&state_) != STATE_CREATED)
PlatformThread::YieldCurrentThread();
}
}
} // namespace base
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