reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2015 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 | |
bungeman | 2c4bd07 | 2016-04-08 06:58:51 -0700 | [diff] [blame] | 8 | #include "SkAtomics.h" |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 9 | #include "SkRWBuffer.h" |
| 10 | #include "SkStream.h" |
| 11 | |
| 12 | // Force small chunks to be a page's worth |
| 13 | static const size_t kMinAllocSize = 4096; |
| 14 | |
| 15 | struct SkBufferBlock { |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 16 | SkBufferBlock* fNext; // updated by the writer |
| 17 | size_t fUsed; // updated by the writer |
| 18 | const size_t fCapacity; |
| 19 | |
| 20 | SkBufferBlock(size_t capacity) : fNext(nullptr), fUsed(0), fCapacity(capacity) {} |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 21 | |
Mike Klein | fc6c37b | 2016-09-27 09:34:10 -0400 | [diff] [blame] | 22 | const void* startData() const { return this + 1; } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 23 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 24 | size_t avail() const { return fCapacity - fUsed; } |
| 25 | void* availData() { return (char*)this->startData() + fUsed; } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 26 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 27 | static SkBufferBlock* Alloc(size_t length) { |
| 28 | size_t capacity = LengthToCapacity(length); |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 29 | void* buffer = sk_malloc_throw(sizeof(SkBufferBlock) + capacity); |
| 30 | return new (buffer) SkBufferBlock(capacity); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 31 | } |
| 32 | |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 33 | // Return number of bytes actually appended. Important that we always completely this block |
| 34 | // before spilling into the next, since the reader uses fCapacity to know how many it can read. |
| 35 | // |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 36 | size_t append(const void* src, size_t length) { |
| 37 | this->validate(); |
| 38 | size_t amount = SkTMin(this->avail(), length); |
| 39 | memcpy(this->availData(), src, amount); |
| 40 | fUsed += amount; |
| 41 | this->validate(); |
| 42 | return amount; |
| 43 | } |
| 44 | |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 45 | // Do not call in the reader thread, since the writer may be updating fUsed. |
| 46 | // (The assertion is still true, but TSAN still may complain about its raciness.) |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 47 | void validate() const { |
| 48 | #ifdef SK_DEBUG |
| 49 | SkASSERT(fCapacity > 0); |
| 50 | SkASSERT(fUsed <= fCapacity); |
| 51 | #endif |
| 52 | } |
| 53 | |
| 54 | private: |
| 55 | static size_t LengthToCapacity(size_t length) { |
| 56 | const size_t minSize = kMinAllocSize - sizeof(SkBufferBlock); |
| 57 | return SkTMax(length, minSize); |
| 58 | } |
| 59 | }; |
| 60 | |
| 61 | struct SkBufferHead { |
| 62 | mutable int32_t fRefCnt; |
| 63 | SkBufferBlock fBlock; |
| 64 | |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 65 | SkBufferHead(size_t capacity) : fRefCnt(1), fBlock(capacity) {} |
| 66 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 67 | static size_t LengthToCapacity(size_t length) { |
| 68 | const size_t minSize = kMinAllocSize - sizeof(SkBufferHead); |
| 69 | return SkTMax(length, minSize); |
| 70 | } |
| 71 | |
| 72 | static SkBufferHead* Alloc(size_t length) { |
| 73 | size_t capacity = LengthToCapacity(length); |
| 74 | size_t size = sizeof(SkBufferHead) + capacity; |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 75 | void* buffer = sk_malloc_throw(size); |
| 76 | return new (buffer) SkBufferHead(capacity); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 77 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 78 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 79 | void ref() const { |
| 80 | SkASSERT(fRefCnt > 0); |
| 81 | sk_atomic_inc(&fRefCnt); |
| 82 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 83 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 84 | void unref() const { |
| 85 | SkASSERT(fRefCnt > 0); |
| 86 | // A release here acts in place of all releases we "should" have been doing in ref(). |
| 87 | if (1 == sk_atomic_fetch_add(&fRefCnt, -1, sk_memory_order_acq_rel)) { |
| 88 | // Like unique(), the acquire is only needed on success. |
| 89 | SkBufferBlock* block = fBlock.fNext; |
| 90 | sk_free((void*)this); |
| 91 | while (block) { |
| 92 | SkBufferBlock* next = block->fNext; |
| 93 | sk_free(block); |
| 94 | block = next; |
| 95 | } |
| 96 | } |
| 97 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 98 | |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 99 | void validate(size_t minUsed, const SkBufferBlock* tail = nullptr) const { |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 100 | #ifdef SK_DEBUG |
| 101 | SkASSERT(fRefCnt > 0); |
| 102 | size_t totalUsed = 0; |
| 103 | const SkBufferBlock* block = &fBlock; |
| 104 | const SkBufferBlock* lastBlock = block; |
| 105 | while (block) { |
| 106 | block->validate(); |
| 107 | totalUsed += block->fUsed; |
| 108 | lastBlock = block; |
| 109 | block = block->fNext; |
| 110 | } |
| 111 | SkASSERT(minUsed <= totalUsed); |
| 112 | if (tail) { |
| 113 | SkASSERT(tail == lastBlock); |
| 114 | } |
| 115 | #endif |
| 116 | } |
| 117 | }; |
| 118 | |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 119 | /////////////////////////////////////////////////////////////////////////////////////////////////// |
| 120 | // The reader can only access block.fCapacity (which never changes), and cannot access |
| 121 | // block.fUsed, which may be updated by the writer. |
| 122 | // |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 123 | SkROBuffer::SkROBuffer(const SkBufferHead* head, size_t available, const SkBufferBlock* tail) |
| 124 | : fHead(head), fAvailable(available), fTail(tail) |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 125 | { |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 126 | if (head) { |
| 127 | fHead->ref(); |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 128 | SkASSERT(available > 0); |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 129 | head->validate(available, tail); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 130 | } else { |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 131 | SkASSERT(0 == available); |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 132 | SkASSERT(!tail); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 133 | } |
| 134 | } |
| 135 | |
| 136 | SkROBuffer::~SkROBuffer() { |
| 137 | if (fHead) { |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 138 | fHead->unref(); |
| 139 | } |
| 140 | } |
| 141 | |
| 142 | SkROBuffer::Iter::Iter(const SkROBuffer* buffer) { |
| 143 | this->reset(buffer); |
| 144 | } |
| 145 | |
| 146 | void SkROBuffer::Iter::reset(const SkROBuffer* buffer) { |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 147 | fBuffer = buffer; |
| 148 | if (buffer && buffer->fHead) { |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 149 | fBlock = &buffer->fHead->fBlock; |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 150 | fRemaining = buffer->fAvailable; |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 151 | } else { |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 152 | fBlock = nullptr; |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 153 | fRemaining = 0; |
| 154 | } |
| 155 | } |
| 156 | |
| 157 | const void* SkROBuffer::Iter::data() const { |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 158 | return fRemaining ? fBlock->startData() : nullptr; |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 159 | } |
| 160 | |
| 161 | size_t SkROBuffer::Iter::size() const { |
scroggo | b512aaa | 2016-01-11 06:38:00 -0800 | [diff] [blame] | 162 | if (!fBlock) { |
| 163 | return 0; |
| 164 | } |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 165 | return SkTMin(fBlock->fCapacity, fRemaining); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 166 | } |
| 167 | |
| 168 | bool SkROBuffer::Iter::next() { |
| 169 | if (fRemaining) { |
| 170 | fRemaining -= this->size(); |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 171 | if (fBuffer->fTail == fBlock) { |
| 172 | // There are more blocks, but fBuffer does not know about them. |
| 173 | SkASSERT(0 == fRemaining); |
| 174 | fBlock = nullptr; |
| 175 | } else { |
| 176 | fBlock = fBlock->fNext; |
| 177 | } |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 178 | } |
| 179 | return fRemaining != 0; |
| 180 | } |
| 181 | |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 182 | /////////////////////////////////////////////////////////////////////////////////////////////////// |
| 183 | |
fmalita | 2e36e88 | 2016-09-30 10:52:08 -0700 | [diff] [blame] | 184 | SkRWBuffer::SkRWBuffer(size_t initialCapacity) : fHead(nullptr), fTail(nullptr), fTotalUsed(0) { |
| 185 | if (initialCapacity) { |
| 186 | fHead = SkBufferHead::Alloc(initialCapacity); |
| 187 | fTail = &fHead->fBlock; |
| 188 | } |
| 189 | } |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 190 | |
| 191 | SkRWBuffer::~SkRWBuffer() { |
| 192 | this->validate(); |
scroggo | 9dec5d2 | 2016-02-16 06:59:18 -0800 | [diff] [blame] | 193 | if (fHead) { |
| 194 | fHead->unref(); |
| 195 | } |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 196 | } |
| 197 | |
reed | 377add7 | 2016-04-08 12:47:14 -0700 | [diff] [blame] | 198 | // It is important that we always completely fill the current block before spilling over to the |
| 199 | // next, since our reader will be using fCapacity (min'd against its total available) to know how |
| 200 | // many bytes to read from a given block. |
| 201 | // |
fmalita | 5776508 | 2016-09-30 13:34:19 -0700 | [diff] [blame] | 202 | void SkRWBuffer::append(const void* src, size_t length, size_t reserve) { |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 203 | this->validate(); |
| 204 | if (0 == length) { |
| 205 | return; |
| 206 | } |
| 207 | |
| 208 | fTotalUsed += length; |
| 209 | |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 210 | if (nullptr == fHead) { |
fmalita | 5776508 | 2016-09-30 13:34:19 -0700 | [diff] [blame] | 211 | fHead = SkBufferHead::Alloc(length + reserve); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 212 | fTail = &fHead->fBlock; |
| 213 | } |
| 214 | |
| 215 | size_t written = fTail->append(src, length); |
| 216 | SkASSERT(written <= length); |
| 217 | src = (const char*)src + written; |
| 218 | length -= written; |
| 219 | |
| 220 | if (length) { |
fmalita | 5776508 | 2016-09-30 13:34:19 -0700 | [diff] [blame] | 221 | SkBufferBlock* block = SkBufferBlock::Alloc(length + reserve); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 222 | fTail->fNext = block; |
| 223 | fTail = block; |
| 224 | written = fTail->append(src, length); |
| 225 | SkASSERT(written == length); |
| 226 | } |
| 227 | this->validate(); |
| 228 | } |
| 229 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 230 | #ifdef SK_DEBUG |
| 231 | void SkRWBuffer::validate() const { |
| 232 | if (fHead) { |
| 233 | fHead->validate(fTotalUsed, fTail); |
| 234 | } else { |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 235 | SkASSERT(nullptr == fTail); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 236 | SkASSERT(0 == fTotalUsed); |
| 237 | } |
| 238 | } |
| 239 | #endif |
| 240 | |
scroggo | 6351640 | 2016-04-22 06:59:01 -0700 | [diff] [blame] | 241 | SkROBuffer* SkRWBuffer::newRBufferSnapshot() const { |
| 242 | return new SkROBuffer(fHead, fTotalUsed, fTail); |
| 243 | } |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 244 | |
| 245 | /////////////////////////////////////////////////////////////////////////////////////////////////// |
| 246 | |
| 247 | class SkROBufferStreamAsset : public SkStreamAsset { |
| 248 | void validate() const { |
| 249 | #ifdef SK_DEBUG |
| 250 | SkASSERT(fGlobalOffset <= fBuffer->size()); |
| 251 | SkASSERT(fLocalOffset <= fIter.size()); |
| 252 | SkASSERT(fLocalOffset <= fGlobalOffset); |
| 253 | #endif |
| 254 | } |
| 255 | |
| 256 | #ifdef SK_DEBUG |
| 257 | class AutoValidate { |
| 258 | SkROBufferStreamAsset* fStream; |
| 259 | public: |
| 260 | AutoValidate(SkROBufferStreamAsset* stream) : fStream(stream) { stream->validate(); } |
| 261 | ~AutoValidate() { fStream->validate(); } |
| 262 | }; |
| 263 | #define AUTO_VALIDATE AutoValidate av(this); |
| 264 | #else |
| 265 | #define AUTO_VALIDATE |
| 266 | #endif |
| 267 | |
| 268 | public: |
| 269 | SkROBufferStreamAsset(const SkROBuffer* buffer) : fBuffer(SkRef(buffer)), fIter(buffer) { |
| 270 | fGlobalOffset = fLocalOffset = 0; |
| 271 | } |
| 272 | |
| 273 | virtual ~SkROBufferStreamAsset() { fBuffer->unref(); } |
| 274 | |
| 275 | size_t getLength() const override { return fBuffer->size(); } |
| 276 | |
| 277 | bool rewind() override { |
| 278 | AUTO_VALIDATE |
| 279 | fIter.reset(fBuffer); |
| 280 | fGlobalOffset = fLocalOffset = 0; |
| 281 | return true; |
| 282 | } |
| 283 | |
| 284 | size_t read(void* dst, size_t request) override { |
| 285 | AUTO_VALIDATE |
| 286 | size_t bytesRead = 0; |
| 287 | for (;;) { |
| 288 | size_t size = fIter.size(); |
| 289 | SkASSERT(fLocalOffset <= size); |
| 290 | size_t avail = SkTMin(size - fLocalOffset, request - bytesRead); |
| 291 | if (dst) { |
| 292 | memcpy(dst, (const char*)fIter.data() + fLocalOffset, avail); |
| 293 | dst = (char*)dst + avail; |
| 294 | } |
| 295 | bytesRead += avail; |
| 296 | fLocalOffset += avail; |
| 297 | SkASSERT(bytesRead <= request); |
| 298 | if (bytesRead == request) { |
| 299 | break; |
| 300 | } |
| 301 | // If we get here, we've exhausted the current iter |
| 302 | SkASSERT(fLocalOffset == size); |
| 303 | fLocalOffset = 0; |
| 304 | if (!fIter.next()) { |
| 305 | break; // ran out of data |
| 306 | } |
| 307 | } |
| 308 | fGlobalOffset += bytesRead; |
| 309 | SkASSERT(fGlobalOffset <= fBuffer->size()); |
| 310 | return bytesRead; |
| 311 | } |
| 312 | |
| 313 | bool isAtEnd() const override { |
| 314 | return fBuffer->size() == fGlobalOffset; |
| 315 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 316 | |
halcanary | 385fe4d | 2015-08-26 13:07:48 -0700 | [diff] [blame] | 317 | SkStreamAsset* duplicate() const override { return new SkROBufferStreamAsset(fBuffer); } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 318 | |
| 319 | size_t getPosition() const override { |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 320 | return fGlobalOffset; |
| 321 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 322 | |
| 323 | bool seek(size_t position) override { |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 324 | AUTO_VALIDATE |
| 325 | if (position < fGlobalOffset) { |
| 326 | this->rewind(); |
| 327 | } |
| 328 | (void)this->skip(position - fGlobalOffset); |
| 329 | return true; |
| 330 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 331 | |
| 332 | bool move(long offset) override{ |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 333 | AUTO_VALIDATE |
| 334 | offset += fGlobalOffset; |
| 335 | if (offset <= 0) { |
| 336 | this->rewind(); |
| 337 | } else { |
| 338 | (void)this->seek(SkToSizeT(offset)); |
| 339 | } |
| 340 | return true; |
| 341 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 342 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 343 | SkStreamAsset* fork() const override { |
| 344 | SkStreamAsset* clone = this->duplicate(); |
| 345 | clone->seek(this->getPosition()); |
| 346 | return clone; |
| 347 | } |
mtklein | f059900 | 2015-07-13 06:18:39 -0700 | [diff] [blame] | 348 | |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 349 | |
| 350 | private: |
| 351 | const SkROBuffer* fBuffer; |
| 352 | SkROBuffer::Iter fIter; |
| 353 | size_t fLocalOffset; |
| 354 | size_t fGlobalOffset; |
| 355 | }; |
| 356 | |
| 357 | SkStreamAsset* SkRWBuffer::newStreamSnapshot() const { |
| 358 | SkAutoTUnref<SkROBuffer> buffer(this->newRBufferSnapshot()); |
halcanary | 385fe4d | 2015-08-26 13:07:48 -0700 | [diff] [blame] | 359 | return new SkROBufferStreamAsset(buffer); |
reed | 5b6db07 | 2015-04-28 17:50:31 -0700 | [diff] [blame] | 360 | } |