1 /* 2 * Copyright (C) 2011 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #ifndef PODFreeListArena_h 27 #define PODFreeListArena_h 28 29 #include "platform/PODArena.h" 30 31 namespace WebCore { 32 33 template <class T> 34 class PODFreeListArena : public RefCounted<PODFreeListArena<T> > { 35 public: create()36 static PassRefPtr<PODFreeListArena> create() 37 { 38 return adoptRef(new PODFreeListArena); 39 } 40 41 // Creates a new PODFreeListArena configured with the given Allocator. create(PassRefPtr<PODArena::Allocator> allocator)42 static PassRefPtr<PODFreeListArena> create(PassRefPtr<PODArena::Allocator> allocator) 43 { 44 return adoptRef(new PODFreeListArena(allocator)); 45 } 46 47 // Allocates an object from the arena. allocateObject()48 T* allocateObject() 49 { 50 void* ptr = allocateFromFreeList(); 51 52 if (ptr) { 53 // Use placement operator new to allocate a T at this location. 54 new(ptr) T(); 55 return static_cast<T*>(ptr); 56 } 57 58 // PODArena::allocateObject calls T's constructor. 59 return static_cast<T*>(m_arena->allocateObject<T>()); 60 } 61 allocateObject(const Argument1Type & argument1)62 template<class Argument1Type> T* allocateObject(const Argument1Type& argument1) 63 { 64 void* ptr = allocateFromFreeList(); 65 66 if (ptr) { 67 // Use placement operator new to allocate a T at this location. 68 new(ptr) T(argument1); 69 return static_cast<T*>(ptr); 70 } 71 72 // PODArena::allocateObject calls T's constructor. 73 return static_cast<T*>(m_arena->allocateObject<T>(argument1)); 74 } 75 freeObject(T * ptr)76 void freeObject(T* ptr) 77 { 78 FixedSizeMemoryChunk* oldFreeList = m_freeList; 79 80 m_freeList = reinterpret_cast<FixedSizeMemoryChunk*>(ptr); 81 m_freeList->next = oldFreeList; 82 } 83 84 private: PODFreeListArena()85 PODFreeListArena() 86 : m_arena(PODArena::create()), m_freeList(0) { } 87 PODFreeListArena(PassRefPtr<PODArena::Allocator> allocator)88 explicit PODFreeListArena(PassRefPtr<PODArena::Allocator> allocator) 89 : m_arena(PODArena::create(allocator)), m_freeList(0) { } 90 ~PODFreeListArena()91 ~PODFreeListArena() { } 92 allocateFromFreeList()93 void* allocateFromFreeList() 94 { 95 if (m_freeList) { 96 void* memory = m_freeList; 97 m_freeList = m_freeList->next; 98 return memory; 99 } 100 return 0; 101 } 102 getFreeListSizeForTesting()103 int getFreeListSizeForTesting() const 104 { 105 int total = 0; 106 for (FixedSizeMemoryChunk* cur = m_freeList; cur; cur = cur->next) { 107 total++; 108 } 109 return total; 110 } 111 112 RefPtr<PODArena> m_arena; 113 114 // This free list contains pointers within every chunk that's been allocated so 115 // far. None of the individual chunks can be freed until the arena is 116 // destroyed. 117 struct FixedSizeMemoryChunk { 118 FixedSizeMemoryChunk* next; 119 }; 120 FixedSizeMemoryChunk* m_freeList; 121 122 COMPILE_ASSERT(sizeof(T) >= sizeof(FixedSizeMemoryChunk), PODFreeListArena_type_should_be_larger); 123 124 friend class WTF::RefCounted<PODFreeListArena>; 125 friend class PODFreeListArenaTest; 126 }; 127 128 } // namespace WebCore 129 130 #endif 131