diff -r 000000000000 -r 6474c204b198 ipc/chromium/src/base/lazy_instance.cc --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ipc/chromium/src/base/lazy_instance.cc Wed Dec 31 06:09:35 2014 +0100 @@ -0,0 +1,34 @@ +// 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