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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 (this is not added to | |
266 // done_headers_queue for performance and consumer's expectations to be | |
267 // synchronous in knowing that headers have been received) | |
268 // add_to_entry_queue-> headers_transaction -> done_headers_queue -> readers | |
269 // (once the data is written to the cache by another writer) | |
270 // | |
271 // Read only transactions: | |
272 // add_to_entry_queue-> headers_transaction -> done_headers_queue -> readers | |
273 // (once the data is written to the cache by the writer) | |
274 | |
251 struct ActiveEntry { | 275 struct ActiveEntry { |
252 explicit ActiveEntry(disk_cache::Entry* entry); | 276 explicit ActiveEntry(disk_cache::Entry* entry); |
253 ~ActiveEntry(); | 277 ~ActiveEntry(); |
254 size_t EstimateMemoryUsage() const; | 278 size_t EstimateMemoryUsage() const; |
255 | 279 |
256 // Returns true if no transactions are associated with this entry. | 280 // Returns true if no transactions are associated with this entry. |
257 bool HasNoTransactions(); | 281 bool HasNoTransactions(); |
258 | 282 |
259 disk_cache::Entry* disk_entry; | 283 // Returns true if no active readers/writer transactions are associated |
260 Transaction* writer; | 284 // with this entry. |
285 bool HasNoActiveTransactions(); | |
286 | |
287 disk_cache::Entry* disk_entry = nullptr; | |
288 | |
289 // Transactions waiting to be added to entry. | |
290 TransactionList add_to_entry_queue; | |
291 | |
292 // Transaction currently in the headers phase, either validating the | |
293 // response or getting new headers. This can exist simultaneously with | |
294 // writer or readers while validating existing headers. | |
295 Transaction* headers_transaction = nullptr; | |
296 | |
297 // Transactions that have completed their headers phase and are waiting | |
298 // to read the response body or write the response body. | |
299 TransactionList done_headers_queue; | |
300 | |
301 // Transaction currently reading from the network and writing to the cache. | |
302 Transaction* writer = nullptr; | |
303 | |
304 // Transactions that can only read from the cache. Only one of writer or | |
305 // readers can exist at a time. | |
261 TransactionSet readers; | 306 TransactionSet readers; |
262 TransactionList pending_queue; | 307 |
263 bool will_process_pending_queue; | 308 // The following variables are true if OnProcessQueuedTransactions is posted |
264 bool doomed; | 309 bool will_process_queued_transactions = false; |
310 | |
311 // True if entry is doomed. | |
312 bool doomed = false; | |
265 }; | 313 }; |
266 | 314 |
267 using ActiveEntriesMap = | 315 using ActiveEntriesMap = |
268 std::unordered_map<std::string, std::unique_ptr<ActiveEntry>>; | 316 std::unordered_map<std::string, std::unique_ptr<ActiveEntry>>; |
269 using PendingOpsMap = std::unordered_map<std::string, PendingOp*>; | 317 using PendingOpsMap = std::unordered_map<std::string, PendingOp*>; |
270 using ActiveEntriesSet = std::map<ActiveEntry*, std::unique_ptr<ActiveEntry>>; | 318 using ActiveEntriesSet = std::map<ActiveEntry*, std::unique_ptr<ActiveEntry>>; |
271 using PlaybackCacheMap = std::unordered_map<std::string, int>; | 319 using PlaybackCacheMap = std::unordered_map<std::string, int>; |
272 | 320 |
273 // Methods ------------------------------------------------------------------ | 321 // Methods ------------------------------------------------------------------ |
274 | 322 |
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335 | 383 |
336 // Creates the disk cache entry associated with |key|, returning an | 384 // Creates the disk cache entry associated with |key|, returning an |
337 // ActiveEntry in |*entry|. |trans| will be notified via its IO callback if | 385 // ActiveEntry in |*entry|. |trans| will be notified via its IO callback if |
338 // this method returns ERR_IO_PENDING. | 386 // this method returns ERR_IO_PENDING. |
339 int CreateEntry(const std::string& key, ActiveEntry** entry, | 387 int CreateEntry(const std::string& key, ActiveEntry** entry, |
340 Transaction* trans); | 388 Transaction* trans); |
341 | 389 |
342 // Destroys an ActiveEntry (active or doomed). | 390 // Destroys an ActiveEntry (active or doomed). |
343 void DestroyEntry(ActiveEntry* entry); | 391 void DestroyEntry(ActiveEntry* entry); |
344 | 392 |
345 // Adds a transaction to an ActiveEntry. If this method returns ERR_IO_PENDING | 393 // 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 | 394 // 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 | 395 // 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 | 396 int AddTransactionToEntry(ActiveEntry* entry, Transaction* transaction); |
349 // one (in this case, the entry is no longer valid). | 397 |
350 int AddTransactionToEntry(ActiveEntry* entry, Transaction* trans); | 398 // Transaction invokes this when its response headers phase is complete |
399 // If the transaction is responsible for writing the response body, | |
400 // it becomes the writer and returns OK. In other cases the transaction it | |
Randy Smith (Not in Mondays)
2017/04/19 17:26:34
nit: Remove "it".
shivanisha
2017/04/21 23:06:00
done
| |
401 // returns ERR_IO_PENDING and the transaction will be notified about | |
402 // completion via its IO callback. In a failure case, the callback will be | |
403 // invoked with ERR_CACHE_RACE. | |
404 int DoneWithResponseHeaders(ActiveEntry* entry, Transaction* transaction); | |
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 int response_code) 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; | |
367 | 457 |
368 // Returns the LoadState of the provided pending transaction. | 458 // Returns the LoadState of the provided pending transaction. |
369 LoadState GetLoadStateForPendingTransaction(const Transaction* trans); | 459 LoadState GetLoadStateForPendingTransaction(const Transaction* trans); |
370 | 460 |
371 // Removes the transaction |trans|, from the pending list of an entry | 461 // Removes the transaction |trans|, from the pending list of an entry |
372 // (PendingOp, active or doomed entry). | 462 // (PendingOp, active or doomed entry). |
373 void RemovePendingTransaction(Transaction* trans); | 463 void RemovePendingTransaction(Transaction* trans); |
374 | 464 |
375 // Removes the transaction |trans|, from the pending list of |entry|. | 465 // Removes the transaction |trans|, from the pending list of |entry|. |
376 bool RemovePendingTransactionFromEntry(ActiveEntry* entry, | 466 bool RemovePendingTransactionFromEntry(ActiveEntry* entry, |
377 Transaction* trans); | 467 Transaction* trans); |
378 | 468 |
379 // Removes the transaction |trans|, from the pending list of |pending_op|. | 469 // Removes the transaction |trans|, from the pending list of |pending_op|. |
380 bool RemovePendingTransactionFromPendingOp(PendingOp* pending_op, | 470 bool RemovePendingTransactionFromPendingOp(PendingOp* pending_op, |
381 Transaction* trans); | 471 Transaction* trans); |
382 // Resumes processing the pending list of |entry|. | |
383 void ProcessPendingQueue(ActiveEntry* entry); | |
384 | 472 |
385 // Events (called via PostTask) --------------------------------------------- | 473 // Events (called via PostTask) --------------------------------------------- |
386 | 474 |
387 void OnProcessPendingQueue(ActiveEntry* entry); | 475 void OnProcessQueuedTransactions(ActiveEntry* entry); |
388 | 476 |
389 // Callbacks ---------------------------------------------------------------- | 477 // Callbacks ---------------------------------------------------------------- |
390 | 478 |
391 // Processes BackendCallback notifications. | 479 // Processes BackendCallback notifications. |
392 void OnIOComplete(int result, PendingOp* entry); | 480 void OnIOComplete(int result, PendingOp* entry); |
393 | 481 |
394 // Helper to conditionally delete |pending_op| if the HttpCache object it | 482 // Helper to conditionally delete |pending_op| if the HttpCache object it |
395 // is meant for has been deleted. | 483 // is meant for has been deleted. |
396 // | 484 // |
397 // TODO(ajwong): The PendingOp lifetime management is very tricky. It might | 485 // TODO(ajwong): The PendingOp lifetime management is very tricky. It might |
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435 std::unique_ptr<base::Clock> clock_; | 523 std::unique_ptr<base::Clock> clock_; |
436 | 524 |
437 base::WeakPtrFactory<HttpCache> weak_factory_; | 525 base::WeakPtrFactory<HttpCache> weak_factory_; |
438 | 526 |
439 DISALLOW_COPY_AND_ASSIGN(HttpCache); | 527 DISALLOW_COPY_AND_ASSIGN(HttpCache); |
440 }; | 528 }; |
441 | 529 |
442 } // namespace net | 530 } // namespace net |
443 | 531 |
444 #endif // NET_HTTP_HTTP_CACHE_H_ | 532 #endif // NET_HTTP_HTTP_CACHE_H_ |
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