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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // This file declares a HttpTransactionFactory implementation that can be | 5 // This file declares a HttpTransactionFactory implementation that can be |
6 // layered on top of another HttpTransactionFactory to add HTTP caching. The | 6 // layered on top of another HttpTransactionFactory to add HTTP caching. The |
7 // caching logic follows RFC 7234 (any exceptions are called out in the code). | 7 // caching logic follows RFC 7234 (any exceptions are called out in the code). |
8 // | 8 // |
9 // The HttpCache takes a disk_cache::Backend as a parameter, and uses that for | 9 // The HttpCache takes a disk_cache::Backend as a parameter, and uses that for |
10 // the cache storage. | 10 // the cache storage. |
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237 }; | 237 }; |
238 | 238 |
239 class MetadataWriter; | 239 class MetadataWriter; |
240 class QuicServerInfoFactoryAdaptor; | 240 class QuicServerInfoFactoryAdaptor; |
241 class Transaction; | 241 class Transaction; |
242 class WorkItem; | 242 class WorkItem; |
243 friend class Transaction; | 243 friend class Transaction; |
244 friend class ViewCacheHelper; | 244 friend class ViewCacheHelper; |
245 struct PendingOp; // Info for an entry under construction. | 245 struct PendingOp; // Info for an entry under construction. |
246 | 246 |
| 247 // To help with testing. |
| 248 friend class MockHttpCache; |
| 249 |
247 using TransactionList = std::list<Transaction*>; | 250 using TransactionList = std::list<Transaction*>; |
248 using TransactionSet = std::unordered_set<Transaction*>; | 251 using TransactionSet = std::unordered_set<Transaction*>; |
249 typedef std::list<std::unique_ptr<WorkItem>> WorkItemList; | 252 typedef std::list<std::unique_ptr<WorkItem>> WorkItemList; |
250 | 253 |
| 254 // We implement a basic reader/writer lock for the disk cache entry. If there |
| 255 // is a writer, then all transactions must wait to read the body. But the |
| 256 // waiting transactions can start their headers phase in parallel. Headers |
| 257 // phase is allowed for one transaction at a time so that if it doesn't match |
| 258 // the existing headers, remaining transactions do not also try to match the |
| 259 // existing entry in parallel leading to wasted network requests. If the |
| 260 // headers do not match, this entry will be doomed. |
| 261 // |
| 262 // A transaction goes through these state transitions. |
| 263 // |
| 264 // Write mode transactions: |
| 265 // add_to_entry_queue-> headers_transaction -> writer |
| 266 // add_to_entry_queue-> headers_transaction -> done_headers_queue -> readers |
| 267 // (once the data is written to the cache by another writer) |
| 268 // |
| 269 // Read only transactions: |
| 270 // add_to_entry_queue-> headers_transaction -> done_headers_queue -> readers |
| 271 // (once the data is written to the cache by the writer) |
| 272 |
251 struct ActiveEntry { | 273 struct ActiveEntry { |
252 explicit ActiveEntry(disk_cache::Entry* entry); | 274 explicit ActiveEntry(disk_cache::Entry* entry); |
253 ~ActiveEntry(); | 275 ~ActiveEntry(); |
254 size_t EstimateMemoryUsage() const; | 276 size_t EstimateMemoryUsage() const; |
255 | 277 |
256 // Returns true if no transactions are associated with this entry. | 278 // Returns true if no transactions are associated with this entry. |
257 bool HasNoTransactions(); | 279 bool HasNoTransactions(); |
258 | 280 |
259 disk_cache::Entry* disk_entry; | 281 // Returns true if no active readers/writer transactions are associated |
260 Transaction* writer; | 282 // with this entry. |
| 283 bool HasNoActiveTransactions(); |
| 284 |
| 285 disk_cache::Entry* disk_entry = nullptr; |
| 286 |
| 287 // Transactions waiting to be added to entry. |
| 288 TransactionList add_to_entry_queue; |
| 289 |
| 290 // Transaction currently in the headers phase, either validating the |
| 291 // response or getting new headers. This can exist simultaneously with |
| 292 // writer or readers while validating existing headers. |
| 293 Transaction* headers_transaction = nullptr; |
| 294 |
| 295 // Transactions that have completed their headers phase and are waiting |
| 296 // to read the response body or write the response body. |
| 297 TransactionList done_headers_queue; |
| 298 |
| 299 // Transaction currently reading from the network and writing to the cache. |
| 300 Transaction* writer = nullptr; |
| 301 |
| 302 // Transactions that can only read from the cache. Only one of writer or |
| 303 // readers can exist at a time. |
261 TransactionSet readers; | 304 TransactionSet readers; |
262 TransactionList pending_queue; | 305 |
263 bool will_process_pending_queue; | 306 // The following variables are true if OnProcessQueuedTransactions is posted |
264 bool doomed; | 307 bool will_process_queued_transactions = false; |
| 308 |
| 309 // True if entry is doomed. |
| 310 bool doomed = false; |
265 }; | 311 }; |
266 | 312 |
267 using ActiveEntriesMap = | 313 using ActiveEntriesMap = |
268 std::unordered_map<std::string, std::unique_ptr<ActiveEntry>>; | 314 std::unordered_map<std::string, std::unique_ptr<ActiveEntry>>; |
269 using PendingOpsMap = std::unordered_map<std::string, PendingOp*>; | 315 using PendingOpsMap = std::unordered_map<std::string, PendingOp*>; |
270 using ActiveEntriesSet = std::map<ActiveEntry*, std::unique_ptr<ActiveEntry>>; | 316 using ActiveEntriesSet = std::map<ActiveEntry*, std::unique_ptr<ActiveEntry>>; |
271 using PlaybackCacheMap = std::unordered_map<std::string, int>; | 317 using PlaybackCacheMap = std::unordered_map<std::string, int>; |
272 | 318 |
273 // Methods ------------------------------------------------------------------ | 319 // Methods ------------------------------------------------------------------ |
274 | 320 |
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335 | 381 |
336 // Creates the disk cache entry associated with |key|, returning an | 382 // Creates the disk cache entry associated with |key|, returning an |
337 // ActiveEntry in |*entry|. |trans| will be notified via its IO callback if | 383 // ActiveEntry in |*entry|. |trans| will be notified via its IO callback if |
338 // this method returns ERR_IO_PENDING. | 384 // this method returns ERR_IO_PENDING. |
339 int CreateEntry(const std::string& key, ActiveEntry** entry, | 385 int CreateEntry(const std::string& key, ActiveEntry** entry, |
340 Transaction* trans); | 386 Transaction* trans); |
341 | 387 |
342 // Destroys an ActiveEntry (active or doomed). | 388 // Destroys an ActiveEntry (active or doomed). |
343 void DestroyEntry(ActiveEntry* entry); | 389 void DestroyEntry(ActiveEntry* entry); |
344 | 390 |
345 // Adds a transaction to an ActiveEntry. If this method returns ERR_IO_PENDING | 391 // Adds a transaction to an ActiveEntry. This method returns ERR_IO_PENDING |
346 // the transaction will be notified about completion via its IO callback. This | 392 // and the transaction will be notified about completion via its IO callback. |
347 // method returns ERR_CACHE_RACE to signal the transaction that it cannot be | 393 // In a failure case, the callback will be invoked with ERR_CACHE_RACE. |
348 // added to the provided entry, and it should retry the process with another | 394 int AddTransactionToEntry(ActiveEntry* entry, Transaction* transaction); |
349 // one (in this case, the entry is no longer valid). | 395 |
350 int AddTransactionToEntry(ActiveEntry* entry, Transaction* trans); | 396 // Transaction invokes this when its response headers phase is complete |
| 397 // If the transaction is responsible for writing the response body, |
| 398 // it becomes the writer and returns OK. In other cases ERR_IO_PENDING is |
| 399 // returned and the transaction will be notified about completion via its |
| 400 // IO callback. In a failure case, the callback will be invoked with |
| 401 // ERR_CACHE_RACE. |
| 402 int DoneWithResponseHeaders(ActiveEntry* entry, |
| 403 Transaction* transaction, |
| 404 bool is_partial); |
351 | 405 |
352 // Called when the transaction has finished working with this entry. |cancel| | 406 // Called when the transaction has finished working with this entry. |cancel| |
353 // is true if the operation was cancelled by the caller instead of running | 407 // is true if the operation was cancelled by the caller instead of running |
354 // to completion. | 408 // to completion. |
355 void DoneWithEntry(ActiveEntry* entry, Transaction* trans, bool cancel); | 409 void DoneWithEntry(ActiveEntry* entry, Transaction* transaction, bool cancel); |
356 | 410 |
357 // Called when the transaction has finished writing to this entry. |success| | 411 // Called when the transaction has finished writing to this entry. |success| |
358 // is false if the cache entry should be deleted. | 412 // is false if the cache entry should be deleted. |
359 void DoneWritingToEntry(ActiveEntry* entry, bool success); | 413 void DoneWritingToEntry(ActiveEntry* entry, |
| 414 bool success, |
| 415 Transaction* transaction); |
360 | 416 |
361 // Called when the transaction has finished reading from this entry. | 417 // Called when the transaction has finished reading from this entry. |
362 void DoneReadingFromEntry(ActiveEntry* entry, Transaction* trans); | 418 void DoneReadingFromEntry(ActiveEntry* entry, Transaction* transaction); |
363 | 419 |
364 // Converts the active writer transaction to a reader so that other | 420 // Removes and returns all queued transactions in |entry| in FIFO order. This |
365 // transactions can start reading from this entry. | 421 // includes transactions that have completed the headers phase and those that |
366 void ConvertWriterToReader(ActiveEntry* entry); | 422 // have not been added to the entry yet in that order. |list| is the output |
| 423 // argument. |
| 424 void RemoveAllQueuedTransactions(ActiveEntry* entry, TransactionList* list); |
| 425 |
| 426 // Processes either writer's failure to write response body or |
| 427 // headers_transactions's failure to write headers. Also invoked when headers |
| 428 // transaction's validation result is not a match. |
| 429 void ProcessEntryFailure(ActiveEntry* entry); |
| 430 |
| 431 // Resumes processing the queued transactions of |entry|. |
| 432 void ProcessQueuedTransactions(ActiveEntry* entry); |
| 433 |
| 434 // Checks if a transaction can be added to the entry. If yes, it will |
| 435 // invoke the IO callback of the transaction. This is a helper function for |
| 436 // OnProcessQueuedTransactions. It will take a transaction from |
| 437 // add_to_entry_queue and make it a headers_transaction, if one doesn't exist |
| 438 // already. |
| 439 void ProcessAddToEntryQueue(ActiveEntry* entry); |
| 440 |
| 441 // Invoked when a transaction that has already completed the response headers |
| 442 // phase can resume reading/writing the response body. It will invoke the IO |
| 443 // callback of the transaction. This is a helper function for |
| 444 // OnProcessQueuedTransactions. |
| 445 void ProcessDoneHeadersQueue(ActiveEntry* entry); |
| 446 |
| 447 // Returns true if this transaction can write headers to the entry. |
| 448 bool CanTransactionWriteResponseHeaders(ActiveEntry* entry, |
| 449 Transaction* transaction, |
| 450 bool is_match) const; |
| 451 |
| 452 // Returns true if |transaction| is about to start writing response body or |
| 453 // already started but not yet finished. |
| 454 bool IsTransactionWritingIncomplete(ActiveEntry* entry, |
| 455 Transaction* transaction, |
| 456 const std::string& method) const; |
| 457 |
| 458 // Returns true if a transaction is currently writing the response body. |
| 459 bool IsWritingInProgress(ActiveEntry* entry) const; |
367 | 460 |
368 // Returns the LoadState of the provided pending transaction. | 461 // Returns the LoadState of the provided pending transaction. |
369 LoadState GetLoadStateForPendingTransaction(const Transaction* trans); | 462 LoadState GetLoadStateForPendingTransaction(const Transaction* trans); |
370 | 463 |
371 // Removes the transaction |trans|, from the pending list of an entry | 464 // Removes the transaction |trans|, from the pending list of an entry |
372 // (PendingOp, active or doomed entry). | 465 // (PendingOp, active or doomed entry). |
373 void RemovePendingTransaction(Transaction* trans); | 466 void RemovePendingTransaction(Transaction* trans); |
374 | 467 |
375 // Removes the transaction |trans|, from the pending list of |entry|. | 468 // Removes the transaction |trans|, from the pending list of |entry|. |
376 bool RemovePendingTransactionFromEntry(ActiveEntry* entry, | 469 bool RemovePendingTransactionFromEntry(ActiveEntry* entry, |
377 Transaction* trans); | 470 Transaction* trans); |
378 | 471 |
379 // Removes the transaction |trans|, from the pending list of |pending_op|. | 472 // Removes the transaction |trans|, from the pending list of |pending_op|. |
380 bool RemovePendingTransactionFromPendingOp(PendingOp* pending_op, | 473 bool RemovePendingTransactionFromPendingOp(PendingOp* pending_op, |
381 Transaction* trans); | 474 Transaction* trans); |
382 // Resumes processing the pending list of |entry|. | |
383 void ProcessPendingQueue(ActiveEntry* entry); | |
384 | 475 |
385 // Events (called via PostTask) --------------------------------------------- | 476 // Events (called via PostTask) --------------------------------------------- |
386 | 477 |
387 void OnProcessPendingQueue(ActiveEntry* entry); | 478 void OnProcessQueuedTransactions(ActiveEntry* entry); |
388 | 479 |
389 // Callbacks ---------------------------------------------------------------- | 480 // Callbacks ---------------------------------------------------------------- |
390 | 481 |
391 // Processes BackendCallback notifications. | 482 // Processes BackendCallback notifications. |
392 void OnIOComplete(int result, PendingOp* entry); | 483 void OnIOComplete(int result, PendingOp* entry); |
393 | 484 |
394 // Helper to conditionally delete |pending_op| if the HttpCache object it | 485 // Helper to conditionally delete |pending_op| if the HttpCache object it |
395 // is meant for has been deleted. | 486 // is meant for has been deleted. |
396 // | 487 // |
397 // TODO(ajwong): The PendingOp lifetime management is very tricky. It might | 488 // TODO(ajwong): The PendingOp lifetime management is very tricky. It might |
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435 std::unique_ptr<base::Clock> clock_; | 526 std::unique_ptr<base::Clock> clock_; |
436 | 527 |
437 base::WeakPtrFactory<HttpCache> weak_factory_; | 528 base::WeakPtrFactory<HttpCache> weak_factory_; |
438 | 529 |
439 DISALLOW_COPY_AND_ASSIGN(HttpCache); | 530 DISALLOW_COPY_AND_ASSIGN(HttpCache); |
440 }; | 531 }; |
441 | 532 |
442 } // namespace net | 533 } // namespace net |
443 | 534 |
444 #endif // NET_HTTP_HTTP_CACHE_H_ | 535 #endif // NET_HTTP_HTTP_CACHE_H_ |
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