1 /*
2 * Copyright 2010 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #ifndef GrAllocator_DEFINED
9 #define GrAllocator_DEFINED
10
11 #include "GrConfig.h"
12 #include "GrTypes.h"
13 #include "SkTArray.h"
14 #include "SkTypes.h"
15
16 class GrAllocator : SkNoncopyable {
17 public:
~GrAllocator()18 ~GrAllocator() { this->reset(); }
19
20 /**
21 * Create an allocator
22 *
23 * @param itemSize the size of each item to allocate
24 * @param itemsPerBlock the number of items to allocate at once
25 * @param initialBlock optional memory to use for the first block.
26 * Must be at least itemSize*itemsPerBlock sized.
27 * Caller is responsible for freeing this memory.
28 */
GrAllocator(size_t itemSize,int itemsPerBlock,void * initialBlock)29 GrAllocator(size_t itemSize, int itemsPerBlock, void* initialBlock)
30 : fItemSize(itemSize)
31 , fItemsPerBlock(itemsPerBlock)
32 , fOwnFirstBlock(NULL == initialBlock)
33 , fCount(0)
34 , fInsertionIndexInBlock(0) {
35 SkASSERT(itemsPerBlock > 0);
36 fBlockSize = fItemSize * fItemsPerBlock;
37 if (fOwnFirstBlock) {
38 // This force us to allocate a new block on push_back().
39 fInsertionIndexInBlock = fItemsPerBlock;
40 } else {
41 fBlocks.push_back() = initialBlock;
42 fInsertionIndexInBlock = 0;
43 }
44 }
45
46 /**
47 * Adds an item and returns pointer to it.
48 *
49 * @return pointer to the added item.
50 */
push_back()51 void* push_back() {
52 // we always have at least one block
53 if (fItemsPerBlock == fInsertionIndexInBlock) {
54 fBlocks.push_back() = sk_malloc_throw(fBlockSize);
55 fInsertionIndexInBlock = 0;
56 }
57 void* ret = (char*)fBlocks.back() + fItemSize * fInsertionIndexInBlock;
58 ++fCount;
59 ++fInsertionIndexInBlock;
60 return ret;
61 }
62
63 /**
64 * Remove the last item, only call if count() != 0
65 */
pop_back()66 void pop_back() {
67 SkASSERT(fCount);
68 SkASSERT(fInsertionIndexInBlock > 0);
69 --fInsertionIndexInBlock;
70 --fCount;
71 if (0 == fInsertionIndexInBlock) {
72 // Never delete the first block
73 if (fBlocks.count() > 1) {
74 sk_free(fBlocks.back());
75 fBlocks.pop_back();
76 fInsertionIndexInBlock = fItemsPerBlock;
77 }
78 }
79 }
80
81 /**
82 * Removes all added items.
83 */
reset()84 void reset() {
85 int firstBlockToFree = fOwnFirstBlock ? 0 : 1;
86 for (int i = firstBlockToFree; i < fBlocks.count(); ++i) {
87 sk_free(fBlocks[i]);
88 }
89 if (fOwnFirstBlock) {
90 fBlocks.reset();
91 // This force us to allocate a new block on push_back().
92 fInsertionIndexInBlock = fItemsPerBlock;
93 } else {
94 fBlocks.pop_back_n(fBlocks.count() - 1);
95 fInsertionIndexInBlock = 0;
96 }
97 fCount = 0;
98 }
99
100 /**
101 * Returns the item count.
102 */
count()103 int count() const {
104 return fCount;
105 }
106
107 /**
108 * Is the count 0?
109 */
empty()110 bool empty() const { return 0 == fCount; }
111
112 /**
113 * Access last item, only call if count() != 0
114 */
back()115 void* back() {
116 SkASSERT(fCount);
117 SkASSERT(fInsertionIndexInBlock > 0);
118 return (char*)(fBlocks.back()) + (fInsertionIndexInBlock - 1) * fItemSize;
119 }
120
121 /**
122 * Access last item, only call if count() != 0
123 */
back()124 const void* back() const {
125 SkASSERT(fCount);
126 SkASSERT(fInsertionIndexInBlock > 0);
127 return (const char*)(fBlocks.back()) + (fInsertionIndexInBlock - 1) * fItemSize;
128 }
129
130 /**
131 * Iterates through the allocator. This is faster than using operator[] when walking linearly
132 * through the allocator.
133 */
134 class Iter {
135 public:
136 /**
137 * Initializes the iterator. next() must be called before get().
138 */
Iter(const GrAllocator * allocator)139 Iter(const GrAllocator* allocator)
140 : fAllocator(allocator)
141 , fBlockIndex(-1)
142 , fIndexInBlock(allocator->fItemsPerBlock - 1)
143 , fItemIndex(-1) {}
144
145 /**
146 * Advances the iterator. Iteration is finished when next() returns false.
147 */
next()148 bool next() {
149 ++fIndexInBlock;
150 ++fItemIndex;
151 if (fIndexInBlock == fAllocator->fItemsPerBlock) {
152 ++fBlockIndex;
153 fIndexInBlock = 0;
154 }
155 return fItemIndex < fAllocator->fCount;
156 }
157
158 /**
159 * Gets the current iterator value. Call next() at least once before calling. Don't call
160 * after next() returns false.
161 */
get()162 void* get() const {
163 SkASSERT(fItemIndex >= 0 && fItemIndex < fAllocator->fCount);
164 return (char*) fAllocator->fBlocks[fBlockIndex] + fIndexInBlock * fAllocator->fItemSize;
165 }
166
167 private:
168 const GrAllocator* fAllocator;
169 int fBlockIndex;
170 int fIndexInBlock;
171 int fItemIndex;
172 };
173
174 /**
175 * Access item by index.
176 */
177 void* operator[] (int i) {
178 SkASSERT(i >= 0 && i < fCount);
179 return (char*)fBlocks[i / fItemsPerBlock] +
180 fItemSize * (i % fItemsPerBlock);
181 }
182
183 /**
184 * Access item by index.
185 */
186 const void* operator[] (int i) const {
187 SkASSERT(i >= 0 && i < fCount);
188 return (const char*)fBlocks[i / fItemsPerBlock] +
189 fItemSize * (i % fItemsPerBlock);
190 }
191
192 protected:
193 /**
194 * Set first block of memory to write into. Must be called before any other methods.
195 * This requires that you have passed NULL in the constructor.
196 *
197 * @param initialBlock optional memory to use for the first block.
198 * Must be at least itemSize*itemsPerBlock sized.
199 * Caller is responsible for freeing this memory.
200 */
setInitialBlock(void * initialBlock)201 void setInitialBlock(void* initialBlock) {
202 SkASSERT(0 == fCount);
203 SkASSERT(0 == fBlocks.count());
204 SkASSERT(fItemsPerBlock == fInsertionIndexInBlock);
205 fOwnFirstBlock = false;
206 fBlocks.push_back() = initialBlock;
207 fInsertionIndexInBlock = 0;
208 }
209
210 // For access to above function.
211 template <typename T> friend class GrTAllocator;
212
213 private:
214 static const int NUM_INIT_BLOCK_PTRS = 8;
215
216 SkSTArray<NUM_INIT_BLOCK_PTRS, void*, true> fBlocks;
217 size_t fBlockSize;
218 size_t fItemSize;
219 int fItemsPerBlock;
220 bool fOwnFirstBlock;
221 int fCount;
222 int fInsertionIndexInBlock;
223
224 typedef SkNoncopyable INHERITED;
225 };
226
227 template <typename T> class GrTAllocator;
228 template <typename T> void* operator new(size_t, GrTAllocator<T>*);
229
230 template <typename T> class GrTAllocator : SkNoncopyable {
231 public:
~GrTAllocator()232 virtual ~GrTAllocator() { this->reset(); };
233
234 /**
235 * Create an allocator
236 *
237 * @param itemsPerBlock the number of items to allocate at once
238 */
GrTAllocator(int itemsPerBlock)239 explicit GrTAllocator(int itemsPerBlock)
240 : fAllocator(sizeof(T), itemsPerBlock, NULL) {}
241
242 /**
243 * Adds an item and returns it.
244 *
245 * @return the added item.
246 */
push_back()247 T& push_back() {
248 void* item = fAllocator.push_back();
249 SkASSERT(item);
250 SkNEW_PLACEMENT(item, T);
251 return *(T*)item;
252 }
253
push_back(const T & t)254 T& push_back(const T& t) {
255 void* item = fAllocator.push_back();
256 SkASSERT(item);
257 SkNEW_PLACEMENT_ARGS(item, T, (t));
258 return *(T*)item;
259 }
260
261 /**
262 * Remove the last item, only call if count() != 0
263 */
pop_back()264 void pop_back() {
265 this->back().~T();
266 fAllocator.pop_back();
267 }
268
269 /**
270 * Removes all added items.
271 */
reset()272 void reset() {
273 int c = fAllocator.count();
274 for (int i = 0; i < c; ++i) {
275 ((T*)fAllocator[i])->~T();
276 }
277 fAllocator.reset();
278 }
279
280 /**
281 * Returns the item count.
282 */
count()283 int count() const {
284 return fAllocator.count();
285 }
286
287 /**
288 * Is the count 0?
289 */
empty()290 bool empty() const { return fAllocator.empty(); }
291
292 /**
293 * Access last item, only call if count() != 0
294 */
back()295 T& back() {
296 return *(T*)fAllocator.back();
297 }
298
299 /**
300 * Access last item, only call if count() != 0
301 */
back()302 const T& back() const {
303 return *(const T*)fAllocator.back();
304 }
305
306 /**
307 * Iterates through the allocator. This is faster than using operator[] when walking linearly
308 * through the allocator.
309 */
310 class Iter {
311 public:
312 /**
313 * Initializes the iterator. next() must be called before get() or ops * and ->.
314 */
Iter(const GrTAllocator * allocator)315 Iter(const GrTAllocator* allocator) : fImpl(&allocator->fAllocator) {}
316
317 /**
318 * Advances the iterator. Iteration is finished when next() returns false.
319 */
next()320 bool next() { return fImpl.next(); }
321
322 /**
323 * Gets the current iterator value. Call next() at least once before calling. Don't call
324 * after next() returns false.
325 */
get()326 T* get() const { return (T*) fImpl.get(); }
327
328 /**
329 * Convenience operators. Same rules for calling apply as get().
330 */
331 T& operator*() const { return *this->get(); }
332 T* operator->() const { return this->get(); }
333
334 private:
335 GrAllocator::Iter fImpl;
336 };
337
338 /**
339 * Access item by index.
340 */
341 T& operator[] (int i) {
342 return *(T*)(fAllocator[i]);
343 }
344
345 /**
346 * Access item by index.
347 */
348 const T& operator[] (int i) const {
349 return *(const T*)(fAllocator[i]);
350 }
351
352 protected:
353 /*
354 * Set first block of memory to write into. Must be called before any other methods.
355 *
356 * @param initialBlock optional memory to use for the first block.
357 * Must be at least size(T)*itemsPerBlock sized.
358 * Caller is responsible for freeing this memory.
359 */
setInitialBlock(void * initialBlock)360 void setInitialBlock(void* initialBlock) {
361 fAllocator.setInitialBlock(initialBlock);
362 }
363
364 private:
365 friend void* operator new<T>(size_t, GrTAllocator*);
366
367 GrAllocator fAllocator;
368 typedef SkNoncopyable INHERITED;
369 };
370
371 template <int N, typename T> class GrSTAllocator : public GrTAllocator<T> {
372 private:
373 typedef GrTAllocator<T> INHERITED;
374
375 public:
GrSTAllocator()376 GrSTAllocator() : INHERITED(N) {
377 this->setInitialBlock(fStorage.get());
378 }
379
380 private:
381 SkAlignedSTStorage<N, T> fStorage;
382 };
383
new(size_t size,GrTAllocator<T> * allocator)384 template <typename T> void* operator new(size_t size, GrTAllocator<T>* allocator) {
385 return allocator->fAllocator.push_back();
386 }
387
388 // Skia doesn't use C++ exceptions but it may be compiled with them enabled. Having an op delete
389 // to match the op new silences warnings about missing op delete when a constructor throws an
390 // exception.
delete(void *,GrTAllocator<T> *)391 template <typename T> void operator delete(void*, GrTAllocator<T>*) {
392 SK_CRASH();
393 }
394
395 #define GrNEW_APPEND_TO_ALLOCATOR(allocator_ptr, type_name, args) \
396 new (allocator_ptr) type_name args
397
398 #endif
399