src/net/http/http_cache.cc

   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
   3 // found in the LICENSE file.
   4
   5 #include "net/http/http_cache.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/compiler_specific.h"
  10
  11 #if defined(OS_POSIX)
  12 #include <unistd.h>
  13 #endif
  14
  15 #include "base/bind.h"
  16 #include "base/bind_helpers.h"
  17 #include "base/callback.h"
  18 #include "base/files/file_util.h"
  19 #include "base/format_macros.h"
  20 #include "base/location.h"
  21 #include "base/memory/ref_counted.h"
  22 #include "base/message_loop/message_loop.h"
  23 #include "base/metrics/field_trial.h"
  24 #include "base/pickle.h"
  25 #include "base/stl_util.h"
  26 #include "base/strings/string_number_conversions.h"
  27 #include "base/strings/string_util.h"
  28 #include "base/strings/stringprintf.h"
  29 #include "base/threading/worker_pool.h"
  30 #include "net/base/cache_type.h"
  31 #include "net/base/io_buffer.h"
  32 #include "net/base/load_flags.h"
  33 #include "net/base/net_errors.h"
  34 #include "net/base/upload_data_stream.h"
  35 #include "net/disk_cache/disk_cache.h"
  36 #include "net/http/disk_based_cert_cache.h"
  37 #include "net/http/disk_cache_based_quic_server_info.h"
  38 #include "net/http/http_cache_transaction.h"
  39 #include "net/http/http_network_layer.h"
  40 #include "net/http/http_network_session.h"
  41 #include "net/http/http_request_info.h"
  42 #include "net/http/http_response_headers.h"
  43 #include "net/http/http_response_info.h"
  44 #include "net/http/http_util.h"
  45 #include "net/quic/crypto/quic_server_info.h"
  46
  47 namespace {
  48
  49 bool UseCertCache() {
  50   return base::FieldTrialList::FindFullName("CertCacheTrial") ==
  51          "ExperimentGroup";
  52 }
  53
  54 // Adaptor to delete a file on a worker thread.
  55 void DeletePath(base::FilePath path) {
  56   base::DeleteFile(path, false);
  57 }
  58
  59 }  // namespace
  60
  61 namespace net {
  62
  63 HttpCache::DefaultBackend::DefaultBackend(
  64     CacheType type,
  65     BackendType backend_type,
  66     const base::FilePath& path,
  67     int max_bytes,
  68     const scoped_refptr<base::SingleThreadTaskRunner>& thread)
  69     : type_(type),
  70       backend_type_(backend_type),
  71       path_(path),
  72       max_bytes_(max_bytes),
  73       thread_(thread) {
  74 }
  75
  76 HttpCache::DefaultBackend::~DefaultBackend() {}
  77
  78 // static
  79 HttpCache::BackendFactory* HttpCache::DefaultBackend::InMemory(int max_bytes) {
  80   return new DefaultBackend(MEMORY_CACHE, net::CACHE_BACKEND_DEFAULT,
  81                             base::FilePath(), max_bytes, NULL);
  82 }
  83
  84 int HttpCache::DefaultBackend::CreateBackend(
  85     NetLog* net_log, scoped_ptr<disk_cache::Backend>* backend,
  86     const CompletionCallback& callback) {
  87   DCHECK_GE(max_bytes_, 0);
  88   return disk_cache::CreateCacheBackend(type_,
  89                                         backend_type_,
  90                                         path_,
  91                                         max_bytes_,
  92                                         true,
  93                                         thread_,
  94                                         net_log,
  95                                         backend,
  96                                         callback);
  97 }
  98
  99 //-----------------------------------------------------------------------------
 100
 101 HttpCache::ActiveEntry::ActiveEntry(disk_cache::Entry* entry)
 102     : disk_entry(entry),
 103       writer(NULL),
 104       will_process_pending_queue(false),
 105       doomed(false) {
 106 }
 107
 108 HttpCache::ActiveEntry::~ActiveEntry() {
 109   if (disk_entry) {
 110     disk_entry->Close();
 111     disk_entry = NULL;
 112   }
 113 }
 114
 115 //-----------------------------------------------------------------------------
 116
 117 // This structure keeps track of work items that are attempting to create or
 118 // open cache entries or the backend itself.
 119 struct HttpCache::PendingOp {
 120   PendingOp() : disk_entry(NULL), writer(NULL) {}
 121   ~PendingOp() {}
 122
 123   disk_cache::Entry* disk_entry;
 124   scoped_ptr<disk_cache::Backend> backend;
 125   WorkItem* writer;
 126   CompletionCallback callback;  // BackendCallback.
 127   WorkItemList pending_queue;
 128 };
 129
 130 //-----------------------------------------------------------------------------
 131
 132 // The type of operation represented by a work item.
 133 enum WorkItemOperation {
 134   WI_CREATE_BACKEND,
 135   WI_OPEN_ENTRY,
 136   WI_CREATE_ENTRY,
 137   WI_DOOM_ENTRY
 138 };
 139
 140 // A work item encapsulates a single request to the backend with all the
 141 // information needed to complete that request.
 142 class HttpCache::WorkItem {
 143  public:
 144   WorkItem(WorkItemOperation operation, Transaction* trans, ActiveEntry** entry)
 145       : operation_(operation),
 146         trans_(trans),
 147         entry_(entry),
 148         backend_(NULL) {}
 149   WorkItem(WorkItemOperation operation, Transaction* trans,
 150            const net::CompletionCallback& cb, disk_cache::Backend** backend)
 151       : operation_(operation),
 152         trans_(trans),
 153         entry_(NULL),
 154         callback_(cb),
 155         backend_(backend) {}
 156   ~WorkItem() {}
 157
 158   // Calls back the transaction with the result of the operation.
 159   void NotifyTransaction(int result, ActiveEntry* entry) {
 160     DCHECK(!entry || entry->disk_entry);
 161     if (entry_)
 162       *entry_ = entry;
 163     if (trans_)
 164       trans_->io_callback().Run(result);
 165   }
 166
 167   // Notifies the caller about the operation completion. Returns true if the
 168   // callback was invoked.
 169   bool DoCallback(int result, disk_cache::Backend* backend) {
 170     if (backend_)
 171       *backend_ = backend;
 172     if (!callback_.is_null()) {
 173       callback_.Run(result);
 174       return true;
 175     }
 176     return false;
 177   }
 178
 179   WorkItemOperation operation() { return operation_; }
 180   void ClearTransaction() { trans_ = NULL; }
 181   void ClearEntry() { entry_ = NULL; }
 182   void ClearCallback() { callback_.Reset(); }
 183   bool Matches(Transaction* trans) const { return trans == trans_; }
 184   bool IsValid() const { return trans_ || entry_ || !callback_.is_null(); }
 185
 186  private:
 187   WorkItemOperation operation_;
 188   Transaction* trans_;
 189   ActiveEntry** entry_;
 190   net::CompletionCallback callback_;  // User callback.
 191   disk_cache::Backend** backend_;
 192 };
 193
 194 //-----------------------------------------------------------------------------
 195
 196 // This class encapsulates a transaction whose only purpose is to write metadata
 197 // to a given entry.
 198 class HttpCache::MetadataWriter {
 199  public:
 200   explicit MetadataWriter(HttpCache::Transaction* trans)
 201       : transaction_(trans),
 202         verified_(false),
 203         buf_len_(0) {
 204   }
 205
 206   ~MetadataWriter() {}
 207
 208   // Implements the bulk of HttpCache::WriteMetadata.
 209   void Write(const GURL& url, base::Time expected_response_time, IOBuffer* buf,
 210              int buf_len);
 211
 212  private:
 213   void VerifyResponse(int result);
 214   void SelfDestroy();
 215   void OnIOComplete(int result);
 216
 217   scoped_ptr<HttpCache::Transaction> transaction_;
 218   bool verified_;
 219   scoped_refptr<IOBuffer> buf_;
 220   int buf_len_;
 221   base::Time expected_response_time_;
 222   HttpRequestInfo request_info_;
 223   DISALLOW_COPY_AND_ASSIGN(MetadataWriter);
 224 };
 225
 226 void HttpCache::MetadataWriter::Write(const GURL& url,
 227                                       base::Time expected_response_time,
 228                                       IOBuffer* buf, int buf_len) {
 229   DCHECK_GT(buf_len, 0);
 230   DCHECK(buf);
 231   DCHECK(buf->data());
 232   request_info_.url = url;
 233   request_info_.method = "GET";
 234   request_info_.load_flags = LOAD_ONLY_FROM_CACHE;
 235
 236   expected_response_time_ = expected_response_time;
 237   buf_ = buf;
 238   buf_len_ = buf_len;
 239   verified_ = false;
 240
 241   int rv = transaction_->Start(
 242       &request_info_,
 243       base::Bind(&MetadataWriter::OnIOComplete, base::Unretained(this)),
 244       BoundNetLog());
 245   if (rv != ERR_IO_PENDING)
 246     VerifyResponse(rv);
 247 }
 248
 249 void HttpCache::MetadataWriter::VerifyResponse(int result) {
 250   verified_ = true;
 251   if (result != OK)
 252     return SelfDestroy();
 253
 254   const HttpResponseInfo* response_info = transaction_->GetResponseInfo();
 255   DCHECK(response_info->was_cached);
 256   if (response_info->response_time != expected_response_time_)
 257     return SelfDestroy();
 258
 259   result = transaction_->WriteMetadata(
 260       buf_.get(),
 261       buf_len_,
 262       base::Bind(&MetadataWriter::OnIOComplete, base::Unretained(this)));
 263   if (result != ERR_IO_PENDING)
 264     SelfDestroy();
 265 }
 266
 267 void HttpCache::MetadataWriter::SelfDestroy() {
 268   delete this;
 269 }
 270
 271 void HttpCache::MetadataWriter::OnIOComplete(int result) {
 272   if (!verified_)
 273     return VerifyResponse(result);
 274   SelfDestroy();
 275 }
 276
 277 //-----------------------------------------------------------------------------
 278
 279 class HttpCache::QuicServerInfoFactoryAdaptor : public QuicServerInfoFactory {
 280  public:
 281   QuicServerInfoFactoryAdaptor(HttpCache* http_cache)
 282       : http_cache_(http_cache) {
 283   }
 284
 285   virtual QuicServerInfo* GetForServer(
 286       const QuicServerId& server_id) OVERRIDE {
 287     return new DiskCacheBasedQuicServerInfo(server_id, http_cache_);
 288   }
 289
 290  private:
 291   HttpCache* const http_cache_;
 292 };
 293
 294 //-----------------------------------------------------------------------------
 295 HttpCache::HttpCache(const net::HttpNetworkSession::Params& params,
 296                      BackendFactory* backend_factory)
 297     : net_log_(params.net_log),
 298       backend_factory_(backend_factory),
 299       building_backend_(false),
 300       bypass_lock_for_test_(false),
 301       mode_(NORMAL),
 302       network_layer_(new HttpNetworkLayer(new HttpNetworkSession(params))),
 303       weak_factory_(this) {
 304   SetupQuicServerInfoFactory(network_layer_->GetSession());
 305 }
 306
 307
 308 // This call doesn't change the shared |session|'s QuicServerInfoFactory because
 309 // |session| is shared.
 310 HttpCache::HttpCache(HttpNetworkSession* session,
 311                      BackendFactory* backend_factory)
 312     : net_log_(session->net_log()),
 313       backend_factory_(backend_factory),
 314       building_backend_(false),
 315       bypass_lock_for_test_(false),
 316       mode_(NORMAL),
 317       network_layer_(new HttpNetworkLayer(session)),
 318       weak_factory_(this) {
 319 }
 320
 321 HttpCache::HttpCache(HttpTransactionFactory* network_layer,
 322                      NetLog* net_log,
 323                      BackendFactory* backend_factory)
 324     : net_log_(net_log),
 325       backend_factory_(backend_factory),
 326       building_backend_(false),
 327       bypass_lock_for_test_(false),
 328       mode_(NORMAL),
 329       network_layer_(network_layer),
 330       weak_factory_(this) {
 331   SetupQuicServerInfoFactory(network_layer_->GetSession());
 332 }
 333
 334 HttpCache::~HttpCache() {
 335   // Transactions should see an invalid cache after this point; otherwise they
 336   // could see an inconsistent object (half destroyed).
 337   weak_factory_.InvalidateWeakPtrs();
 338
 339   // If we have any active entries remaining, then we need to deactivate them.
 340   // We may have some pending calls to OnProcessPendingQueue, but since those
 341   // won't run (due to our destruction), we can simply ignore the corresponding
 342   // will_process_pending_queue flag.
 343   while (!active_entries_.empty()) {
 344     ActiveEntry* entry = active_entries_.begin()->second;
 345     entry->will_process_pending_queue = false;
 346     entry->pending_queue.clear();
 347     entry->readers.clear();
 348     entry->writer = NULL;
 349     DeactivateEntry(entry);
 350   }
 351
 352   STLDeleteElements(&doomed_entries_);
 353
 354   // Before deleting pending_ops_, we have to make sure that the disk cache is
 355   // done with said operations, or it will attempt to use deleted data.
 356   cert_cache_.reset();
 357   disk_cache_.reset();
 358
 359   PendingOpsMap::iterator pending_it = pending_ops_.begin();
 360   for (; pending_it != pending_ops_.end(); ++pending_it) {
 361     // We are not notifying the transactions about the cache going away, even
 362     // though they are waiting for a callback that will never fire.
 363     PendingOp* pending_op = pending_it->second;
 364     delete pending_op->writer;
 365     bool delete_pending_op = true;
 366     if (building_backend_) {
 367       // If we don't have a backend, when its construction finishes it will
 368       // deliver the callbacks.
 369       if (!pending_op->callback.is_null()) {
 370         // If not null, the callback will delete the pending operation later.
 371         delete_pending_op = false;
 372       }
 373     } else {
 374       pending_op->callback.Reset();
 375     }
 376
 377     STLDeleteElements(&pending_op->pending_queue);
 378     if (delete_pending_op)
 379       delete pending_op;
 380   }
 381 }
 382
 383 int HttpCache::GetBackend(disk_cache::Backend** backend,
 384                           const CompletionCallback& callback) {
 385   DCHECK(!callback.is_null());
 386
 387   if (disk_cache_.get()) {
 388     *backend = disk_cache_.get();
 389     return OK;
 390   }
 391
 392   return CreateBackend(backend, callback);
 393 }
 394
 395 disk_cache::Backend* HttpCache::GetCurrentBackend() const {
 396   return disk_cache_.get();
 397 }
 398
 399 // static
 400 bool HttpCache::ParseResponseInfo(const char* data, int len,
 401                                   HttpResponseInfo* response_info,
 402                                   bool* response_truncated) {
 403   Pickle pickle(data, len);
 404   return response_info->InitFromPickle(pickle, response_truncated);
 405 }
 406
 407 void HttpCache::WriteMetadata(const GURL& url,
 408                               RequestPriority priority,
 409                               base::Time expected_response_time,
 410                               IOBuffer* buf,
 411                               int buf_len) {
 412   if (!buf_len)
 413     return;
 414
 415   // Do lazy initialization of disk cache if needed.
 416   if (!disk_cache_.get()) {
 417     // We don't care about the result.
 418     CreateBackend(NULL, net::CompletionCallback());
 419   }
 420
 421   HttpCache::Transaction* trans =
 422       new HttpCache::Transaction(priority, this);
 423   MetadataWriter* writer = new MetadataWriter(trans);
 424
 425   // The writer will self destruct when done.
 426   writer->Write(url, expected_response_time, buf, buf_len);
 427 }
 428
 429 void HttpCache::CloseAllConnections() {
 430   HttpNetworkSession* session = GetSession();
 431   if (session)
 432     session->CloseAllConnections();
 433 }
 434
 435 void HttpCache::CloseIdleConnections() {
 436   HttpNetworkSession* session = GetSession();
 437   if (session)
 438     session->CloseIdleConnections();
 439 }
 440
 441 void HttpCache::OnExternalCacheHit(const GURL& url,
 442                                    const std::string& http_method) {
 443   if (!disk_cache_.get())
 444     return;
 445
 446   HttpRequestInfo request_info;
 447   request_info.url = url;
 448   request_info.method = http_method;
 449   std::string key = GenerateCacheKey(&request_info);
 450   disk_cache_->OnExternalCacheHit(key);
 451 }
 452
 453 void HttpCache::InitializeInfiniteCache(const base::FilePath& path) {
 454   if (base::FieldTrialList::FindFullName("InfiniteCache") != "Yes")
 455     return;
 456   base::WorkerPool::PostTask(FROM_HERE, base::Bind(&DeletePath, path), true);
 457 }
 458
 459 int HttpCache::CreateTransaction(RequestPriority priority,
 460                                  scoped_ptr<HttpTransaction>* trans) {
 461   // Do lazy initialization of disk cache if needed.
 462   if (!disk_cache_.get()) {
 463     // We don't care about the result.
 464     CreateBackend(NULL, net::CompletionCallback());
 465   }
 466
 467    HttpCache::Transaction* transaction =
 468       new HttpCache::Transaction(priority, this);
 469    if (bypass_lock_for_test_)
 470     transaction->BypassLockForTest();
 471
 472   trans->reset(transaction);
 473   return OK;
 474 }
 475
 476 HttpCache* HttpCache::GetCache() {
 477   return this;
 478 }
 479
 480 HttpNetworkSession* HttpCache::GetSession() {
 481   return network_layer_->GetSession();
 482 }
 483
 484 scoped_ptr<HttpTransactionFactory>
 485 HttpCache::SetHttpNetworkTransactionFactoryForTesting(
 486     scoped_ptr<HttpTransactionFactory> new_network_layer) {
 487   scoped_ptr<HttpTransactionFactory> old_network_layer(network_layer_.Pass());
 488   network_layer_ = new_network_layer.Pass();
 489   return old_network_layer.Pass();
 490 }
 491
 492 //-----------------------------------------------------------------------------
 493
 494 int HttpCache::CreateBackend(disk_cache::Backend** backend,
 495                              const net::CompletionCallback& callback) {
 496   if (!backend_factory_.get())
 497     return ERR_FAILED;
 498
 499   building_backend_ = true;
 500
 501   scoped_ptr<WorkItem> item(new WorkItem(WI_CREATE_BACKEND, NULL, callback,
 502                                          backend));
 503
 504   // This is the only operation that we can do that is not related to any given
 505   // entry, so we use an empty key for it.
 506   PendingOp* pending_op = GetPendingOp(std::string());
 507   if (pending_op->writer) {
 508     if (!callback.is_null())
 509       pending_op->pending_queue.push_back(item.release());
 510     return ERR_IO_PENDING;
 511   }
 512
 513   DCHECK(pending_op->pending_queue.empty());
 514
 515   pending_op->writer = item.release();
 516   pending_op->callback = base::Bind(&HttpCache::OnPendingOpComplete,
 517                                     GetWeakPtr(), pending_op);
 518
 519   int rv = backend_factory_->CreateBackend(net_log_, &pending_op->backend,
 520                                            pending_op->callback);
 521   if (rv != ERR_IO_PENDING) {
 522     pending_op->writer->ClearCallback();
 523     pending_op->callback.Run(rv);
 524   }
 525
 526   return rv;
 527 }
 528
 529 int HttpCache::GetBackendForTransaction(Transaction* trans) {
 530   if (disk_cache_.get())
 531     return OK;
 532
 533   if (!building_backend_)
 534     return ERR_FAILED;
 535
 536   WorkItem* item = new WorkItem(
 537       WI_CREATE_BACKEND, trans, net::CompletionCallback(), NULL);
 538   PendingOp* pending_op = GetPendingOp(std::string());
 539   DCHECK(pending_op->writer);
 540   pending_op->pending_queue.push_back(item);
 541   return ERR_IO_PENDING;
 542 }
 543
 544 // Generate a key that can be used inside the cache.
 545 std::string HttpCache::GenerateCacheKey(const HttpRequestInfo* request) {
 546   // Strip out the reference, username, and password sections of the URL.
 547   std::string url = HttpUtil::SpecForRequest(request->url);
 548
 549   DCHECK(mode_ != DISABLE);
 550   if (mode_ == NORMAL) {
 551     // No valid URL can begin with numerals, so we should not have to worry
 552     // about collisions with normal URLs.
 553     if (request->upload_data_stream &&
 554         request->upload_data_stream->identifier()) {
 555       url.insert(0, base::StringPrintf(
 556           "%" PRId64 "/", request->upload_data_stream->identifier()));
 557     }
 558     return url;
 559   }
 560
 561   // In playback and record mode, we cache everything.
 562
 563   // Lazily initialize.
 564   if (playback_cache_map_ == NULL)
 565     playback_cache_map_.reset(new PlaybackCacheMap());
 566
 567   // Each time we request an item from the cache, we tag it with a
 568   // generation number.  During playback, multiple fetches for the same
 569   // item will use the same generation number and pull the proper
 570   // instance of an URL from the cache.
 571   int generation = 0;
 572   DCHECK(playback_cache_map_ != NULL);
 573   if (playback_cache_map_->find(url) != playback_cache_map_->end())
 574     generation = (*playback_cache_map_)[url];
 575   (*playback_cache_map_)[url] = generation + 1;
 576
 577   // The key into the cache is GENERATION # + METHOD + URL.
 578   std::string result = base::IntToString(generation);
 579   result.append(request->method);
 580   result.append(url);
 581   return result;
 582 }
 583
 584 void HttpCache::DoomActiveEntry(const std::string& key) {
 585   ActiveEntriesMap::iterator it = active_entries_.find(key);
 586   if (it == active_entries_.end())
 587     return;
 588
 589   // This is not a performance critical operation, this is handling an error
 590   // condition so it is OK to look up the entry again.
 591   int rv = DoomEntry(key, NULL);
 592   DCHECK_EQ(OK, rv);
 593 }
 594
 595 int HttpCache::DoomEntry(const std::string& key, Transaction* trans) {
 596   // Need to abandon the ActiveEntry, but any transaction attached to the entry
 597   // should not be impacted.  Dooming an entry only means that it will no
 598   // longer be returned by FindActiveEntry (and it will also be destroyed once
 599   // all consumers are finished with the entry).
 600   ActiveEntriesMap::iterator it = active_entries_.find(key);
 601   if (it == active_entries_.end()) {
 602     DCHECK(trans);
 603     return AsyncDoomEntry(key, trans);
 604   }
 605
 606   ActiveEntry* entry = it->second;
 607   active_entries_.erase(it);
 608
 609   // We keep track of doomed entries so that we can ensure that they are
 610   // cleaned up properly when the cache is destroyed.
 611   doomed_entries_.insert(entry);
 612
 613   entry->disk_entry->Doom();
 614   entry->doomed = true;
 615
 616   DCHECK(entry->writer || !entry->readers.empty() ||
 617          entry->will_process_pending_queue);
 618   return OK;
 619 }
 620
 621 int HttpCache::AsyncDoomEntry(const std::string& key, Transaction* trans) {
 622   WorkItem* item = new WorkItem(WI_DOOM_ENTRY, trans, NULL);
 623   PendingOp* pending_op = GetPendingOp(key);
 624   if (pending_op->writer) {
 625     pending_op->pending_queue.push_back(item);
 626     return ERR_IO_PENDING;
 627   }
 628
 629   DCHECK(pending_op->pending_queue.empty());
 630
 631   pending_op->writer = item;
 632   pending_op->callback = base::Bind(&HttpCache::OnPendingOpComplete,
 633                                     GetWeakPtr(), pending_op);
 634
 635   int rv = disk_cache_->DoomEntry(key, pending_op->callback);
 636   if (rv != ERR_IO_PENDING) {
 637     item->ClearTransaction();
 638     pending_op->callback.Run(rv);
 639   }
 640
 641   return rv;
 642 }
 643
 644 void HttpCache::DoomMainEntryForUrl(const GURL& url) {
 645   if (!disk_cache_)
 646     return;
 647
 648   HttpRequestInfo temp_info;
 649   temp_info.url = url;
 650   temp_info.method = "GET";
 651   std::string key = GenerateCacheKey(&temp_info);
 652
 653   // Defer to DoomEntry if there is an active entry, otherwise call
 654   // AsyncDoomEntry without triggering a callback.
 655   if (active_entries_.count(key))
 656     DoomEntry(key, NULL);
 657   else
 658     AsyncDoomEntry(key, NULL);
 659 }
 660
 661 void HttpCache::FinalizeDoomedEntry(ActiveEntry* entry) {
 662   DCHECK(entry->doomed);
 663   DCHECK(!entry->writer);
 664   DCHECK(entry->readers.empty());
 665   DCHECK(entry->pending_queue.empty());
 666
 667   ActiveEntriesSet::iterator it = doomed_entries_.find(entry);
 668   DCHECK(it != doomed_entries_.end());
 669   doomed_entries_.erase(it);
 670
 671   delete entry;
 672 }
 673
 674 HttpCache::ActiveEntry* HttpCache::FindActiveEntry(const std::string& key) {
 675   ActiveEntriesMap::const_iterator it = active_entries_.find(key);
 676   return it != active_entries_.end() ? it->second : NULL;
 677 }
 678
 679 HttpCache::ActiveEntry* HttpCache::ActivateEntry(
 680     disk_cache::Entry* disk_entry) {
 681   DCHECK(!FindActiveEntry(disk_entry->GetKey()));
 682   ActiveEntry* entry = new ActiveEntry(disk_entry);
 683   active_entries_[disk_entry->GetKey()] = entry;
 684   return entry;
 685 }
 686
 687 void HttpCache::DeactivateEntry(ActiveEntry* entry) {
 688   DCHECK(!entry->will_process_pending_queue);
 689   DCHECK(!entry->doomed);
 690   DCHECK(!entry->writer);
 691   DCHECK(entry->disk_entry);
 692   DCHECK(entry->readers.empty());
 693   DCHECK(entry->pending_queue.empty());
 694
 695   std::string key = entry->disk_entry->GetKey();
 696   if (key.empty())
 697     return SlowDeactivateEntry(entry);
 698
 699   ActiveEntriesMap::iterator it = active_entries_.find(key);
 700   DCHECK(it != active_entries_.end());
 701   DCHECK(it->second == entry);
 702
 703   active_entries_.erase(it);
 704   delete entry;
 705 }
 706
 707 // We don't know this entry's key so we have to find it without it.
 708 void HttpCache::SlowDeactivateEntry(ActiveEntry* entry) {
 709   for (ActiveEntriesMap::iterator it = active_entries_.begin();
 710        it != active_entries_.end(); ++it) {
 711     if (it->second == entry) {
 712       active_entries_.erase(it);
 713       delete entry;
 714       break;
 715     }
 716   }
 717 }
 718
 719 HttpCache::PendingOp* HttpCache::GetPendingOp(const std::string& key) {
 720   DCHECK(!FindActiveEntry(key));
 721
 722   PendingOpsMap::const_iterator it = pending_ops_.find(key);
 723   if (it != pending_ops_.end())
 724     return it->second;
 725
 726   PendingOp* operation = new PendingOp();
 727   pending_ops_[key] = operation;
 728   return operation;
 729 }
 730
 731 void HttpCache::DeletePendingOp(PendingOp* pending_op) {
 732   std::string key;
 733   if (pending_op->disk_entry)
 734     key = pending_op->disk_entry->GetKey();
 735
 736   if (!key.empty()) {
 737     PendingOpsMap::iterator it = pending_ops_.find(key);
 738     DCHECK(it != pending_ops_.end());
 739     pending_ops_.erase(it);
 740   } else {
 741     for (PendingOpsMap::iterator it = pending_ops_.begin();
 742          it != pending_ops_.end(); ++it) {
 743       if (it->second == pending_op) {
 744         pending_ops_.erase(it);
 745         break;
 746       }
 747     }
 748   }
 749   DCHECK(pending_op->pending_queue.empty());
 750
 751   delete pending_op;
 752 }
 753
 754 int HttpCache::OpenEntry(const std::string& key, ActiveEntry** entry,
 755                          Transaction* trans) {
 756   ActiveEntry* active_entry = FindActiveEntry(key);
 757   if (active_entry) {
 758     *entry = active_entry;
 759     return OK;
 760   }
 761
 762   WorkItem* item = new WorkItem(WI_OPEN_ENTRY, trans, entry);
 763   PendingOp* pending_op = GetPendingOp(key);
 764   if (pending_op->writer) {
 765     pending_op->pending_queue.push_back(item);
 766     return ERR_IO_PENDING;
 767   }
 768
 769   DCHECK(pending_op->pending_queue.empty());
 770
 771   pending_op->writer = item;
 772   pending_op->callback = base::Bind(&HttpCache::OnPendingOpComplete,
 773                                     GetWeakPtr(), pending_op);
 774
 775   int rv = disk_cache_->OpenEntry(key, &(pending_op->disk_entry),
 776                                   pending_op->callback);
 777   if (rv != ERR_IO_PENDING) {
 778     item->ClearTransaction();
 779     pending_op->callback.Run(rv);
 780   }
 781
 782   return rv;
 783 }
 784
 785 int HttpCache::CreateEntry(const std::string& key, ActiveEntry** entry,
 786                            Transaction* trans) {
 787   if (FindActiveEntry(key)) {
 788     return ERR_CACHE_RACE;
 789   }
 790
 791   WorkItem* item = new WorkItem(WI_CREATE_ENTRY, trans, entry);
 792   PendingOp* pending_op = GetPendingOp(key);
 793   if (pending_op->writer) {
 794     pending_op->pending_queue.push_back(item);
 795     return ERR_IO_PENDING;
 796   }
 797
 798   DCHECK(pending_op->pending_queue.empty());
 799
 800   pending_op->writer = item;
 801   pending_op->callback = base::Bind(&HttpCache::OnPendingOpComplete,
 802                                     GetWeakPtr(), pending_op);
 803
 804   int rv = disk_cache_->CreateEntry(key, &(pending_op->disk_entry),
 805                                     pending_op->callback);
 806   if (rv != ERR_IO_PENDING) {
 807     item->ClearTransaction();
 808     pending_op->callback.Run(rv);
 809   }
 810
 811   return rv;
 812 }
 813
 814 void HttpCache::DestroyEntry(ActiveEntry* entry) {
 815   if (entry->doomed) {
 816     FinalizeDoomedEntry(entry);
 817   } else {
 818     DeactivateEntry(entry);
 819   }
 820 }
 821
 822 int HttpCache::AddTransactionToEntry(ActiveEntry* entry, Transaction* trans) {
 823   DCHECK(entry);
 824   DCHECK(entry->disk_entry);
 825
 826   // We implement a basic reader/writer lock for the disk cache entry.  If
 827   // there is already a writer, then everyone has to wait for the writer to
 828   // finish before they can access the cache entry.  There can be multiple
 829   // readers.
 830   //
 831   // NOTE: If the transaction can only write, then the entry should not be in
 832   // use (since any existing entry should have already been doomed).
 833
 834   if (entry->writer || entry->will_process_pending_queue) {
 835     entry->pending_queue.push_back(trans);
 836     return ERR_IO_PENDING;
 837   }
 838
 839   if (trans->mode() & Transaction::WRITE) {
 840     // transaction needs exclusive access to the entry
 841     if (entry->readers.empty()) {
 842       entry->writer = trans;
 843     } else {
 844       entry->pending_queue.push_back(trans);
 845       return ERR_IO_PENDING;
 846     }
 847   } else {
 848     // transaction needs read access to the entry
 849     entry->readers.push_back(trans);
 850   }
 851
 852   // We do this before calling EntryAvailable to force any further calls to
 853   // AddTransactionToEntry to add their transaction to the pending queue, which
 854   // ensures FIFO ordering.
 855   if (!entry->writer && !entry->pending_queue.empty())
 856     ProcessPendingQueue(entry);
 857
 858   return OK;
 859 }
 860
 861 void HttpCache::DoneWithEntry(ActiveEntry* entry, Transaction* trans,
 862                               bool cancel) {
 863   // If we already posted a task to move on to the next transaction and this was
 864   // the writer, there is nothing to cancel.
 865   if (entry->will_process_pending_queue && entry->readers.empty())
 866     return;
 867
 868   if (entry->writer) {
 869     DCHECK(trans == entry->writer);
 870
 871     // Assume there was a failure.
 872     bool success = false;
 873     if (cancel) {
 874       DCHECK(entry->disk_entry);
 875       // This is a successful operation in the sense that we want to keep the
 876       // entry.
 877       success = trans->AddTruncatedFlag();
 878       // The previous operation may have deleted the entry.
 879       if (!trans->entry())
 880         return;
 881     }
 882     DoneWritingToEntry(entry, success);
 883   } else {
 884     DoneReadingFromEntry(entry, trans);
 885   }
 886 }
 887
 888 void HttpCache::DoneWritingToEntry(ActiveEntry* entry, bool success) {
 889   DCHECK(entry->readers.empty());
 890
 891   entry->writer = NULL;
 892
 893   if (success) {
 894     ProcessPendingQueue(entry);
 895   } else {
 896     DCHECK(!entry->will_process_pending_queue);
 897
 898     // We failed to create this entry.
 899     TransactionList pending_queue;
 900     pending_queue.swap(entry->pending_queue);
 901
 902     entry->disk_entry->Doom();
 903     DestroyEntry(entry);
 904
 905     // We need to do something about these pending entries, which now need to
 906     // be added to a new entry.
 907     while (!pending_queue.empty()) {
 908       // ERR_CACHE_RACE causes the transaction to restart the whole process.
 909       pending_queue.front()->io_callback().Run(ERR_CACHE_RACE);
 910       pending_queue.pop_front();
 911     }
 912   }
 913 }
 914
 915 void HttpCache::DoneReadingFromEntry(ActiveEntry* entry, Transaction* trans) {
 916   DCHECK(!entry->writer);
 917
 918   TransactionList::iterator it =
 919       std::find(entry->readers.begin(), entry->readers.end(), trans);
 920   DCHECK(it != entry->readers.end());
 921
 922   entry->readers.erase(it);
 923
 924   ProcessPendingQueue(entry);
 925 }
 926
 927 void HttpCache::ConvertWriterToReader(ActiveEntry* entry) {
 928   DCHECK(entry->writer);
 929   DCHECK(entry->writer->mode() == Transaction::READ_WRITE);
 930   DCHECK(entry->readers.empty());
 931
 932   Transaction* trans = entry->writer;
 933
 934   entry->writer = NULL;
 935   entry->readers.push_back(trans);
 936
 937   ProcessPendingQueue(entry);
 938 }
 939
 940 LoadState HttpCache::GetLoadStateForPendingTransaction(
 941       const Transaction* trans) {
 942   ActiveEntriesMap::const_iterator i = active_entries_.find(trans->key());
 943   if (i == active_entries_.end()) {
 944     // If this is really a pending transaction, and it is not part of
 945     // active_entries_, we should be creating the backend or the entry.
 946     return LOAD_STATE_WAITING_FOR_CACHE;
 947   }
 948
 949   Transaction* writer = i->second->writer;
 950   return writer ? writer->GetWriterLoadState() : LOAD_STATE_WAITING_FOR_CACHE;
 951 }
 952
 953 void HttpCache::RemovePendingTransaction(Transaction* trans) {
 954   ActiveEntriesMap::const_iterator i = active_entries_.find(trans->key());
 955   bool found = false;
 956   if (i != active_entries_.end())
 957     found = RemovePendingTransactionFromEntry(i->second, trans);
 958
 959   if (found)
 960     return;
 961
 962   if (building_backend_) {
 963     PendingOpsMap::const_iterator j = pending_ops_.find(std::string());
 964     if (j != pending_ops_.end())
 965       found = RemovePendingTransactionFromPendingOp(j->second, trans);
 966
 967     if (found)
 968       return;
 969   }
 970
 971   PendingOpsMap::const_iterator j = pending_ops_.find(trans->key());
 972   if (j != pending_ops_.end())
 973     found = RemovePendingTransactionFromPendingOp(j->second, trans);
 974
 975   if (found)
 976     return;
 977
 978   ActiveEntriesSet::iterator k = doomed_entries_.begin();
 979   for (; k != doomed_entries_.end() && !found; ++k)
 980     found = RemovePendingTransactionFromEntry(*k, trans);
 981
 982   DCHECK(found) << "Pending transaction not found";
 983 }
 984
 985 bool HttpCache::RemovePendingTransactionFromEntry(ActiveEntry* entry,
 986                                                   Transaction* trans) {
 987   TransactionList& pending_queue = entry->pending_queue;
 988
 989   TransactionList::iterator j =
 990       find(pending_queue.begin(), pending_queue.end(), trans);
 991   if (j == pending_queue.end())
 992     return false;
 993
 994   pending_queue.erase(j);
 995   return true;
 996 }
 997
 998 bool HttpCache::RemovePendingTransactionFromPendingOp(PendingOp* pending_op,
 999                                                       Transaction* trans) {
1000   if (pending_op->writer->Matches(trans)) {
1001     pending_op->writer->ClearTransaction();
1002     pending_op->writer->ClearEntry();
1003     return true;
1004   }
1005   WorkItemList& pending_queue = pending_op->pending_queue;
1006
1007   WorkItemList::iterator it = pending_queue.begin();
1008   for (; it != pending_queue.end(); ++it) {
1009     if ((*it)->Matches(trans)) {
1010       delete *it;
1011       pending_queue.erase(it);
1012       return true;
1013     }
1014   }
1015   return false;
1016 }
1017
1018 void HttpCache::SetupQuicServerInfoFactory(HttpNetworkSession* session) {
1019   if (session &&
1020       !session->quic_stream_factory()->has_quic_server_info_factory()) {
1021     DCHECK(!quic_server_info_factory_);
1022     quic_server_info_factory_.reset(new QuicServerInfoFactoryAdaptor(this));
1023     session->quic_stream_factory()->set_quic_server_info_factory(
1024         quic_server_info_factory_.get());
1025   }
1026 }
1027
1028 void HttpCache::ProcessPendingQueue(ActiveEntry* entry) {
1029   // Multiple readers may finish with an entry at once, so we want to batch up
1030   // calls to OnProcessPendingQueue.  This flag also tells us that we should
1031   // not delete the entry before OnProcessPendingQueue runs.
1032   if (entry->will_process_pending_queue)
1033     return;
1034   entry->will_process_pending_queue = true;
1035
1036   base::MessageLoop::current()->PostTask(
1037       FROM_HERE,
1038       base::Bind(&HttpCache::OnProcessPendingQueue, GetWeakPtr(), entry));
1039 }
1040
1041 void HttpCache::OnProcessPendingQueue(ActiveEntry* entry) {
1042   entry->will_process_pending_queue = false;
1043   DCHECK(!entry->writer);
1044
1045   // If no one is interested in this entry, then we can deactivate it.
1046   if (entry->pending_queue.empty()) {
1047     if (entry->readers.empty())
1048       DestroyEntry(entry);
1049     return;
1050   }
1051
1052   // Promote next transaction from the pending queue.
1053   Transaction* next = entry->pending_queue.front();
1054   if ((next->mode() & Transaction::WRITE) && !entry->readers.empty())
1055     return;  // Have to wait.
1056
1057   entry->pending_queue.erase(entry->pending_queue.begin());
1058
1059   int rv = AddTransactionToEntry(entry, next);
1060   if (rv != ERR_IO_PENDING) {
1061     next->io_callback().Run(rv);
1062   }
1063 }
1064
1065 void HttpCache::OnIOComplete(int result, PendingOp* pending_op) {
1066   WorkItemOperation op = pending_op->writer->operation();
1067
1068   // Completing the creation of the backend is simpler than the other cases.
1069   if (op == WI_CREATE_BACKEND)
1070     return OnBackendCreated(result, pending_op);
1071
1072   scoped_ptr<WorkItem> item(pending_op->writer);
1073   bool fail_requests = false;
1074
1075   ActiveEntry* entry = NULL;
1076   std::string key;
1077   if (result == OK) {
1078     if (op == WI_DOOM_ENTRY) {
1079       // Anything after a Doom has to be restarted.
1080       fail_requests = true;
1081     } else if (item->IsValid()) {
1082       key = pending_op->disk_entry->GetKey();
1083       entry = ActivateEntry(pending_op->disk_entry);
1084     } else {
1085       // The writer transaction is gone.
1086       if (op == WI_CREATE_ENTRY)
1087         pending_op->disk_entry->Doom();
1088       pending_op->disk_entry->Close();
1089       pending_op->disk_entry = NULL;
1090       fail_requests = true;
1091     }
1092   }
1093
1094   // We are about to notify a bunch of transactions, and they may decide to
1095   // re-issue a request (or send a different one). If we don't delete
1096   // pending_op, the new request will be appended to the end of the list, and
1097   // we'll see it again from this point before it has a chance to complete (and
1098   // we'll be messing out the request order). The down side is that if for some
1099   // reason notifying request A ends up cancelling request B (for the same key),
1100   // we won't find request B anywhere (because it would be in a local variable
1101   // here) and that's bad. If there is a chance for that to happen, we'll have
1102   // to move the callback used to be a CancelableCallback. By the way, for this
1103   // to happen the action (to cancel B) has to be synchronous to the
1104   // notification for request A.
1105   WorkItemList pending_items;
1106   pending_items.swap(pending_op->pending_queue);
1107   DeletePendingOp(pending_op);
1108
1109   item->NotifyTransaction(result, entry);
1110
1111   while (!pending_items.empty()) {
1112     item.reset(pending_items.front());
1113     pending_items.pop_front();
1114
1115     if (item->operation() == WI_DOOM_ENTRY) {
1116       // A queued doom request is always a race.
1117       fail_requests = true;
1118     } else if (result == OK) {
1119       entry = FindActiveEntry(key);
1120       if (!entry)
1121         fail_requests = true;
1122     }
1123
1124     if (fail_requests) {
1125       item->NotifyTransaction(ERR_CACHE_RACE, NULL);
1126       continue;
1127     }
1128
1129     if (item->operation() == WI_CREATE_ENTRY) {
1130       if (result == OK) {
1131         // A second Create request, but the first request succeeded.
1132         item->NotifyTransaction(ERR_CACHE_CREATE_FAILURE, NULL);
1133       } else {
1134         if (op != WI_CREATE_ENTRY) {
1135           // Failed Open followed by a Create.
1136           item->NotifyTransaction(ERR_CACHE_RACE, NULL);
1137           fail_requests = true;
1138         } else {
1139           item->NotifyTransaction(result, entry);
1140         }
1141       }
1142     } else {
1143       if (op == WI_CREATE_ENTRY && result != OK) {
1144         // Failed Create followed by an Open.
1145         item->NotifyTransaction(ERR_CACHE_RACE, NULL);
1146         fail_requests = true;
1147       } else {
1148         item->NotifyTransaction(result, entry);
1149       }
1150     }
1151   }
1152 }
1153
1154 // static
1155 void HttpCache::OnPendingOpComplete(const base::WeakPtr<HttpCache>& cache,
1156                                     PendingOp* pending_op,
1157                                     int rv) {
1158   if (cache.get()) {
1159     cache->OnIOComplete(rv, pending_op);
1160   } else {
1161     // The callback was cancelled so we should delete the pending_op that
1162     // was used with this callback.
1163     delete pending_op;
1164   }
1165 }
1166
1167 void HttpCache::OnBackendCreated(int result, PendingOp* pending_op) {
1168   scoped_ptr<WorkItem> item(pending_op->writer);
1169   WorkItemOperation op = item->operation();
1170   DCHECK_EQ(WI_CREATE_BACKEND, op);
1171
1172   // We don't need the callback anymore.
1173   pending_op->callback.Reset();
1174
1175   if (backend_factory_.get()) {
1176     // We may end up calling OnBackendCreated multiple times if we have pending
1177     // work items. The first call saves the backend and releases the factory,
1178     // and the last call clears building_backend_.
1179     backend_factory_.reset();  // Reclaim memory.
1180     if (result == OK) {
1181       disk_cache_ = pending_op->backend.Pass();
1182       if (UseCertCache())
1183         cert_cache_.reset(new DiskBasedCertCache(disk_cache_.get()));
1184     }
1185   }
1186
1187   if (!pending_op->pending_queue.empty()) {
1188     WorkItem* pending_item = pending_op->pending_queue.front();
1189     pending_op->pending_queue.pop_front();
1190     DCHECK_EQ(WI_CREATE_BACKEND, pending_item->operation());
1191
1192     // We want to process a single callback at a time, because the cache may
1193     // go away from the callback.
1194     pending_op->writer = pending_item;
1195
1196     base::MessageLoop::current()->PostTask(
1197         FROM_HERE,
1198         base::Bind(&HttpCache::OnBackendCreated, GetWeakPtr(),
1199                    result, pending_op));
1200   } else {
1201     building_backend_ = false;
1202     DeletePendingOp(pending_op);
1203   }
1204
1205   // The cache may be gone when we return from the callback.
1206   if (!item->DoCallback(result, disk_cache_.get()))
1207     item->NotifyTransaction(result, NULL);
1208 }
1209
1210 }  // namespace net