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Side by Side Diff: sky/engine/platform/PODArena.h

Issue 705373003: Remove PODIntervalTree and machinery. (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 6 years, 1 month ago
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1 /*
2 * Copyright (C) 2010 Google 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 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
18 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
21 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #ifndef PODArena_h
27 #define PODArena_h
28
29 #include <stdint.h>
30 #include "wtf/Assertions.h"
31 #include "wtf/FastMalloc.h"
32 #include "wtf/Noncopyable.h"
33 #include "wtf/OwnPtr.h"
34 #include "wtf/PassOwnPtr.h"
35 #include "wtf/RefCounted.h"
36 #include "wtf/Vector.h"
37
38 namespace blink {
39
40 // An arena which allocates only Plain Old Data (POD), or classes and
41 // structs bottoming out in Plain Old Data. NOTE: the constructors of
42 // the objects allocated in this arena are called, but _not_ their
43 // destructors.
44
45 class PODArena final : public RefCounted<PODArena> {
46 public:
47 // The arena is configured with an allocator, which is responsible
48 // for allocating and freeing chunks of memory at a time.
49 class Allocator : public RefCounted<Allocator> {
50 public:
51 virtual void* allocate(size_t size) = 0;
52 virtual void free(void* ptr) = 0;
53 protected:
54 virtual ~Allocator() { }
55 friend class WTF::RefCounted<Allocator>;
56 };
57
58 // The Arena's default allocator, which uses fastMalloc and
59 // fastFree to allocate chunks of storage.
60 class FastMallocAllocator : public Allocator {
61 public:
62 static PassRefPtr<FastMallocAllocator> create()
63 {
64 return adoptRef(new FastMallocAllocator);
65 }
66
67 virtual void* allocate(size_t size) override { return fastMalloc(size); }
68 virtual void free(void* ptr) override { fastFree(ptr); }
69
70 protected:
71 FastMallocAllocator() { }
72 };
73
74 // Creates a new PODArena configured with a FastMallocAllocator.
75 static PassRefPtr<PODArena> create()
76 {
77 return adoptRef(new PODArena);
78 }
79
80 // Creates a new PODArena configured with the given Allocator.
81 static PassRefPtr<PODArena> create(PassRefPtr<Allocator> allocator)
82 {
83 return adoptRef(new PODArena(allocator));
84 }
85
86 // Allocates an object from the arena.
87 template<class T> T* allocateObject()
88 {
89 return new (allocateBase<T>()) T();
90 }
91
92 // Allocates an object from the arena, calling a single-argument constructor .
93 template<class T, class Argument1Type> T* allocateObject(const Argument1Type & argument1)
94 {
95 return new (allocateBase<T>()) T(argument1);
96 }
97
98 // The initial size of allocated chunks; increases as necessary to
99 // satisfy large allocations. Mainly public for unit tests.
100 enum {
101 DefaultChunkSize = 16384
102 };
103
104 protected:
105 friend class WTF::RefCounted<PODArena>;
106
107 PODArena()
108 : m_allocator(FastMallocAllocator::create())
109 , m_current(0)
110 , m_currentChunkSize(DefaultChunkSize) { }
111
112 explicit PODArena(PassRefPtr<Allocator> allocator)
113 : m_allocator(allocator)
114 , m_current(0)
115 , m_currentChunkSize(DefaultChunkSize) { }
116
117 // Returns the alignment requirement for classes and structs on the
118 // current platform.
119 template <class T> static size_t minAlignment()
120 {
121 return WTF_ALIGN_OF(T);
122 }
123
124 template<class T> void* allocateBase()
125 {
126 void* ptr = 0;
127 size_t roundedSize = roundUp(sizeof(T), minAlignment<T>());
128 if (m_current)
129 ptr = m_current->allocate(roundedSize);
130
131 if (!ptr) {
132 if (roundedSize > m_currentChunkSize)
133 m_currentChunkSize = roundedSize;
134 m_chunks.append(adoptPtr(new Chunk(m_allocator.get(), m_currentChunk Size)));
135 m_current = m_chunks.last().get();
136 ptr = m_current->allocate(roundedSize);
137 }
138 return ptr;
139 }
140
141 // Rounds up the given allocation size to the specified alignment.
142 size_t roundUp(size_t size, size_t alignment)
143 {
144 ASSERT(!(alignment % 2));
145 return (size + alignment - 1) & ~(alignment - 1);
146 }
147
148 // Manages a chunk of memory and individual allocations out of it.
149 class Chunk final {
150 WTF_MAKE_NONCOPYABLE(Chunk);
151 public:
152 // Allocates a block of memory of the given size from the passed
153 // Allocator.
154 Chunk(Allocator* allocator, size_t size)
155 : m_allocator(allocator)
156 , m_size(size)
157 , m_currentOffset(0)
158 {
159 m_base = static_cast<uint8_t*>(m_allocator->allocate(size));
160 }
161
162 // Frees the memory allocated from the Allocator in the
163 // constructor.
164 ~Chunk()
165 {
166 m_allocator->free(m_base);
167 }
168
169 // Returns a pointer to "size" bytes of storage, or 0 if this
170 // Chunk could not satisfy the allocation.
171 void* allocate(size_t size)
172 {
173 // Check for overflow
174 if (m_currentOffset + size < m_currentOffset)
175 return 0;
176
177 if (m_currentOffset + size > m_size)
178 return 0;
179
180 void* result = m_base + m_currentOffset;
181 m_currentOffset += size;
182 return result;
183 }
184
185 protected:
186 Allocator* m_allocator;
187 uint8_t* m_base;
188 size_t m_size;
189 size_t m_currentOffset;
190 };
191
192 RefPtr<Allocator> m_allocator;
193 Chunk* m_current;
194 size_t m_currentChunkSize;
195 Vector<OwnPtr<Chunk> > m_chunks;
196 };
197
198 } // namespace blink
199
200 #endif // PODArena_h
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