1 : // Copyright (c) 2008 The Chromium Authors. All rights reserved.
2 : // Use of this source code is governed by a BSD-style license that can be
3 : // found in the LICENSE file.
4 :
5 : #include "base/lazy_instance.h"
6 :
7 : #include "base/at_exit.h"
8 : #include "base/atomicops.h"
9 : #include "base/basictypes.h"
10 : #include "base/platform_thread.h"
11 :
12 : namespace base {
13 :
14 4260 : void LazyInstanceHelper::EnsureInstance(void* instance,
15 : void (*ctor)(void*),
16 : void (*dtor)(void*)) {
17 : // Try to create the instance, if we're the first, will go from EMPTY
18 : // to CREATING, otherwise we've already been beaten here.
19 4260 : if (base::subtle::Acquire_CompareAndSwap(
20 4260 : &state_, STATE_EMPTY, STATE_CREATING) == STATE_EMPTY) {
21 : // Created the instance in the space provided by |instance|.
22 4260 : ctor(instance);
23 : // Instance is created, go from CREATING to CREATED.
24 4260 : base::subtle::Release_Store(&state_, STATE_CREATED);
25 : // Register the destructor callback with AtExitManager.
26 4260 : base::AtExitManager::RegisterCallback(dtor, instance);
27 : } else {
28 : // It's either in the process of being created, or already created. Spin.
29 0 : while (base::subtle::NoBarrier_Load(&state_) != STATE_CREATED)
30 0 : PlatformThread::YieldCurrentThread();
31 : }
32 4260 : }
33 :
34 : } // namespace base
|