1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/ipc/chromium/src/base/lazy_instance.cc Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,34 @@
1.4 +// Copyright (c) 2008 The Chromium Authors. All rights reserved.
1.5 +// Use of this source code is governed by a BSD-style license that can be
1.6 +// found in the LICENSE file.
1.7 +
1.8 +#include "base/lazy_instance.h"
1.9 +
1.10 +#include "base/at_exit.h"
1.11 +#include "base/atomicops.h"
1.12 +#include "base/basictypes.h"
1.13 +#include "base/platform_thread.h"
1.14 +
1.15 +namespace base {
1.16 +
1.17 +void LazyInstanceHelper::EnsureInstance(void* instance,
1.18 + void (*ctor)(void*),
1.19 + void (*dtor)(void*)) {
1.20 + // Try to create the instance, if we're the first, will go from EMPTY
1.21 + // to CREATING, otherwise we've already been beaten here.
1.22 + if (base::subtle::Acquire_CompareAndSwap(
1.23 + &state_, STATE_EMPTY, STATE_CREATING) == STATE_EMPTY) {
1.24 + // Created the instance in the space provided by |instance|.
1.25 + ctor(instance);
1.26 + // Instance is created, go from CREATING to CREATED.
1.27 + base::subtle::Release_Store(&state_, STATE_CREATED);
1.28 + // Register the destructor callback with AtExitManager.
1.29 + base::AtExitManager::RegisterCallback(dtor, instance);
1.30 + } else {
1.31 + // It's either in the process of being created, or already created. Spin.
1.32 + while (base::subtle::NoBarrier_Load(&state_) != STATE_CREATED)
1.33 + PlatformThread::YieldCurrentThread();
1.34 + }
1.35 +}
1.36 +
1.37 +} // namespace base
