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Unified Diff: src/lazy-instance.h

Issue 9836108: Rollback of r11015, r11014, r11011, r11010 in trunk branch. (Closed) Base URL: https://v8.googlecode.com/svn/trunk
Patch Set: Finish file upload Created 8 years, 9 months ago
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Index: src/lazy-instance.h
diff --git a/src/lazy-instance.h b/src/lazy-instance.h
deleted file mode 100644
index 09dfe2154dc2992305a0b04787d8c3cca3391193..0000000000000000000000000000000000000000
--- a/src/lazy-instance.h
+++ /dev/null
@@ -1,216 +0,0 @@
-// Copyright 2012 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-// * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-// * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following
-// disclaimer in the documentation and/or other materials provided
-// with the distribution.
-// * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived
-// from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// The LazyInstance<Type, Traits> class manages a single instance of Type,
-// which will be lazily created on the first time it's accessed. This class is
-// useful for places you would normally use a function-level static, but you
-// need to have guaranteed thread-safety. The Type constructor will only ever
-// be called once, even if two threads are racing to create the object. Get()
-// and Pointer() will always return the same, completely initialized instance.
-//
-// LazyInstance is completely thread safe, assuming that you create it safely.
-// The class was designed to be POD initialized, so it shouldn't require a
-// static constructor. It really only makes sense to declare a LazyInstance as
-// a global variable using the LAZY_INSTANCE_INITIALIZER initializer.
-//
-// LazyInstance is similar to Singleton, except it does not have the singleton
-// property. You can have multiple LazyInstance's of the same type, and each
-// will manage a unique instance. It also preallocates the space for Type, as
-// to avoid allocating the Type instance on the heap. This may help with the
-// performance of creating the instance, and reducing heap fragmentation. This
-// requires that Type be a complete type so we can determine the size. See
-// notes for advanced users below for more explanations.
-//
-// Example usage:
-// static LazyInstance<MyClass>::type my_instance = LAZY_INSTANCE_INITIALIZER;
-// void SomeMethod() {
-// my_instance.Get().SomeMethod(); // MyClass::SomeMethod()
-//
-// MyClass* ptr = my_instance.Pointer();
-// ptr->DoDoDo(); // MyClass::DoDoDo
-// }
-//
-// Additionally you can override the way your instance is constructed by
-// providing your own trait:
-// Example usage:
-// struct MyCreateTrait {
-// static void Construct(MyClass* allocated_ptr) {
-// new (allocated_ptr) MyClass(/* extra parameters... */);
-// }
-// };
-// static LazyInstance<MyClass, MyCreateTrait>::type my_instance =
-// LAZY_INSTANCE_INITIALIZER;
-//
-// Notes for advanced users:
-// LazyInstance can actually be used in two different ways:
-//
-// - "Static mode" which is the default mode since it is the most efficient
-// (no extra heap allocation). In this mode, the instance is statically
-// allocated (stored in the global data section at compile time).
-// The macro LAZY_STATIC_INSTANCE_INITIALIZER (= LAZY_INSTANCE_INITIALIZER)
-// must be used to initialize static lazy instances.
-//
-// - "Dynamic mode". In this mode, the instance is dynamically allocated and
-// constructed (using new) by default. This mode is useful if you have to
-// deal with some code already allocating the instance for you (e.g.
-// OS::Mutex() which returns a new private OS-dependent subclass of Mutex).
-// The macro LAZY_DYNAMIC_INSTANCE_INITIALIZER must be used to initialize
-// dynamic lazy instances.
-
-#ifndef V8_LAZY_INSTANCE_H_
-#define V8_LAZY_INSTANCE_H_
-
-#include "once.h"
-
-namespace v8 {
-namespace internal {
-
-#define LAZY_STATIC_INSTANCE_INITIALIZER { V8_ONCE_INIT, {} }
-#define LAZY_DYNAMIC_INSTANCE_INITIALIZER { V8_ONCE_INIT, 0 }
-
-// Default to static mode.
-#define LAZY_INSTANCE_INITIALIZER LAZY_STATIC_INSTANCE_INITIALIZER
-
-
-template <typename T>
-struct LeakyInstanceTrait {
- static void Destroy(T* /* instance */) {}
-};
-
-
-// Traits that define how an instance is allocated and accessed.
-
-template <typename T>
-struct StaticallyAllocatedInstanceTrait {
- typedef char StorageType[sizeof(T)];
-
- static T* MutableInstance(StorageType* storage) {
- return reinterpret_cast<T*>(storage);
- }
-
- template <typename ConstructTrait>
- static void InitStorageUsingTrait(StorageType* storage) {
- ConstructTrait::Construct(MutableInstance(storage));
- }
-};
-
-
-template <typename T>
-struct DynamicallyAllocatedInstanceTrait {
- typedef T* StorageType;
-
- static T* MutableInstance(StorageType* storage) {
- return *storage;
- }
-
- template <typename CreateTrait>
- static void InitStorageUsingTrait(StorageType* storage) {
- *storage = CreateTrait::Create();
- }
-};
-
-
-template <typename T>
-struct DefaultConstructTrait {
- // Constructs the provided object which was already allocated.
- static void Construct(T* allocated_ptr) {
- new(allocated_ptr) T();
- }
-};
-
-
-template <typename T>
-struct DefaultCreateTrait {
- static T* Create() {
- return new T();
- }
-};
-
-
-// TODO(pliard): Handle instances destruction (using global destructors).
-template <typename T, typename AllocationTrait, typename CreateTrait,
- typename DestroyTrait /* not used yet. */ >
-struct LazyInstanceImpl {
- public:
- typedef typename AllocationTrait::StorageType StorageType;
-
- private:
- static void InitInstance(StorageType* storage) {
- AllocationTrait::template InitStorageUsingTrait<CreateTrait>(storage);
- }
-
- void Init() const {
- CallOnce(&once_, &InitInstance, &storage_);
- }
-
- public:
- T* Pointer() {
- Init();
- return AllocationTrait::MutableInstance(&storage_);
- }
-
- const T& Get() const {
- Init();
- return *AllocationTrait::MutableInstance(&storage_);
- }
-
- mutable OnceType once_;
- // Note that the previous field, OnceType, is an AtomicWord which guarantees
- // the correct alignment of the storage field below.
- mutable StorageType storage_;
-};
-
-
-template <typename T,
- typename CreateTrait = DefaultConstructTrait<T>,
- typename DestroyTrait = LeakyInstanceTrait<T> >
-struct LazyStaticInstance {
- typedef LazyInstanceImpl<T, StaticallyAllocatedInstanceTrait<T>, CreateTrait,
- DestroyTrait> type;
-};
-
-
-template <typename T,
- typename CreateTrait = DefaultConstructTrait<T>,
- typename DestroyTrait = LeakyInstanceTrait<T> >
-struct LazyInstance {
- // A LazyInstance is a LazyStaticInstance.
- typedef typename LazyStaticInstance<T, CreateTrait, DestroyTrait>::type type;
-};
-
-
-template <typename T,
- typename CreateTrait = DefaultConstructTrait<T>,
- typename DestroyTrait = LeakyInstanceTrait<T> >
-struct LazyDynamicInstance {
- typedef LazyInstanceImpl<T, DynamicallyAllocatedInstanceTrait<T>, CreateTrait,
- DestroyTrait> type;
-};
-
-} } // namespace v8::internal
-
-#endif // V8_LAZY_INSTANCE_H_
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