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| 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 #include "base/lazy_instance.h" | 5 #include "base/lazy_instance.h" |
| 6 | 6 |
| 7 #include "base/at_exit.h" | 7 #include "base/at_exit.h" |
| 8 #include "base/atomicops.h" | 8 #include "base/atomicops.h" |
| 9 #include "base/basictypes.h" | 9 #include "base/basictypes.h" |
| 10 #include "base/threading/platform_thread.h" | 10 #include "base/threading/platform_thread.h" |
| 11 #include "base/third_party/dynamic_annotations/dynamic_annotations.h" | |
| 12 | 11 |
| 13 namespace base { | 12 namespace base { |
| 14 namespace internal { | 13 namespace internal { |
| 15 | 14 |
| 16 // TODO(joth): This function could be shared with Singleton, in place of its | 15 // TODO(joth): This function could be shared with Singleton, in place of its |
| 17 // WaitForInstance() call. | 16 // WaitForInstance() call. |
| 18 bool NeedsLazyInstance(subtle::AtomicWord* state) { | 17 bool NeedsLazyInstance(subtle::AtomicWord* state) { |
| 19 // Try to create the instance, if we're the first, will go from 0 to | 18 // Try to create the instance, if we're the first, will go from 0 to |
| 20 // kLazyInstanceStateCreating, otherwise we've already been beaten here. | 19 // kLazyInstanceStateCreating, otherwise we've already been beaten here. |
| 21 // The memory access has no memory ordering as state 0 and | 20 // The memory access has no memory ordering as state 0 and |
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| 35 PlatformThread::YieldCurrentThread(); | 34 PlatformThread::YieldCurrentThread(); |
| 36 } | 35 } |
| 37 // Someone else created the instance. | 36 // Someone else created the instance. |
| 38 return false; | 37 return false; |
| 39 } | 38 } |
| 40 | 39 |
| 41 void CompleteLazyInstance(subtle::AtomicWord* state, | 40 void CompleteLazyInstance(subtle::AtomicWord* state, |
| 42 subtle::AtomicWord new_instance, | 41 subtle::AtomicWord new_instance, |
| 43 void* lazy_instance, | 42 void* lazy_instance, |
| 44 void (*dtor)(void*)) { | 43 void (*dtor)(void*)) { |
| 45 // See the comment to the corresponding HAPPENS_AFTER in Pointer(). | |
| 46 ANNOTATE_HAPPENS_BEFORE(state); | |
| 47 | |
| 48 // Instance is created, go from CREATING to CREATED. | 44 // Instance is created, go from CREATING to CREATED. |
| 49 // Releases visibility over private_buf_ to readers. Pairing Acquire_Load's | 45 // Releases visibility over private_buf_ to readers. Pairing Acquire_Load's |
| 50 // are in NeedsInstance() and Pointer(). | 46 // are in NeedsInstance() and Pointer(). |
| 51 subtle::Release_Store(state, new_instance); | 47 subtle::Release_Store(state, new_instance); |
| 52 | 48 |
| 53 // Make sure that the lazily instantiated object will get destroyed at exit. | 49 // Make sure that the lazily instantiated object will get destroyed at exit. |
| 54 if (dtor) | 50 if (dtor) |
| 55 AtExitManager::RegisterCallback(dtor, lazy_instance); | 51 AtExitManager::RegisterCallback(dtor, lazy_instance); |
| 56 } | 52 } |
| 57 | 53 |
| 58 } // namespace internal | 54 } // namespace internal |
| 59 } // namespace base | 55 } // namespace base |
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