net/disk_cache/backend_impl.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/disk_cache/backend_impl.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/file_util.h"
  10 #include "base/files/file_path.h"
  11 #include "base/hash.h"
  12 #include "base/message_loop/message_loop.h"
  13 #include "base/metrics/field_trial.h"
  14 #include "base/metrics/histogram.h"
  15 #include "base/metrics/stats_counters.h"
  16 #include "base/rand_util.h"
  17 #include "base/strings/string_util.h"
  18 #include "base/strings/stringprintf.h"
  19 #include "base/sys_info.h"
  20 #include "base/threading/thread_restrictions.h"
  21 #include "base/time/time.h"
  22 #include "base/timer/timer.h"
  23 #include "net/base/net_errors.h"
  24 #include "net/disk_cache/cache_util.h"
  25 #include "net/disk_cache/disk_format.h"
  26 #include "net/disk_cache/entry_impl.h"
  27 #include "net/disk_cache/errors.h"
  28 #include "net/disk_cache/experiments.h"
  29 #include "net/disk_cache/file.h"
  30
  31 // This has to be defined before including histogram_macros.h from this file.
  32 #define NET_DISK_CACHE_BACKEND_IMPL_CC_
  33 #include "net/disk_cache/histogram_macros.h"
  34
  35 using base::Time;
  36 using base::TimeDelta;
  37 using base::TimeTicks;
  38
  39 namespace {
  40
  41 const char* kIndexName = "index";
  42
  43 // Seems like ~240 MB correspond to less than 50k entries for 99% of the people.
  44 // Note that the actual target is to keep the index table load factor under 55%
  45 // for most users.
  46 const int k64kEntriesStore = 240 * 1000 * 1000;
  47 const int kBaseTableLen = 64 * 1024;
  48 const int kDefaultCacheSize = 80 * 1024 * 1024;
  49
  50 // Avoid trimming the cache for the first 5 minutes (10 timer ticks).
  51 const int kTrimDelay = 10;
  52
  53 int DesiredIndexTableLen(int32 storage_size) {
  54   if (storage_size <= k64kEntriesStore)
  55     return kBaseTableLen;
  56   if (storage_size <= k64kEntriesStore * 2)
  57     return kBaseTableLen * 2;
  58   if (storage_size <= k64kEntriesStore * 4)
  59     return kBaseTableLen * 4;
  60   if (storage_size <= k64kEntriesStore * 8)
  61     return kBaseTableLen * 8;
  62
  63   // The biggest storage_size for int32 requires a 4 MB table.
  64   return kBaseTableLen * 16;
  65 }
  66
  67 int MaxStorageSizeForTable(int table_len) {
  68   return table_len * (k64kEntriesStore / kBaseTableLen);
  69 }
  70
  71 size_t GetIndexSize(int table_len) {
  72   size_t table_size = sizeof(disk_cache::CacheAddr) * table_len;
  73   return sizeof(disk_cache::IndexHeader) + table_size;
  74 }
  75
  76 // ------------------------------------------------------------------------
  77
  78 // Sets group for the current experiment. Returns false if the files should be
  79 // discarded.
  80 bool InitExperiment(disk_cache::IndexHeader* header, bool cache_created) {
  81   if (header->experiment == disk_cache::EXPERIMENT_OLD_FILE1 ||
  82       header->experiment == disk_cache::EXPERIMENT_OLD_FILE2) {
  83     // Discard current cache.
  84     return false;
  85   }
  86
  87   if (base::FieldTrialList::FindFullName("SimpleCacheTrial") ==
  88           "ExperimentControl") {
  89     if (cache_created) {
  90       header->experiment = disk_cache::EXPERIMENT_SIMPLE_CONTROL;
  91       return true;
  92     }
  93     return header->experiment == disk_cache::EXPERIMENT_SIMPLE_CONTROL;
  94   }
  95
  96   header->experiment = disk_cache::NO_EXPERIMENT;
  97   return true;
  98 }
  99
 100 // A callback to perform final cleanup on the background thread.
 101 void FinalCleanupCallback(disk_cache::BackendImpl* backend) {
 102   backend->CleanupCache();
 103 }
 104
 105 }  // namespace
 106
 107 // ------------------------------------------------------------------------
 108
 109 namespace disk_cache {
 110
 111 // Returns the preferred maximum number of bytes for the cache given the
 112 // number of available bytes.
 113 int PreferedCacheSize(int64 available) {
 114   // Return 80% of the available space if there is not enough space to use
 115   // kDefaultCacheSize.
 116   if (available < kDefaultCacheSize * 10 / 8)
 117     return static_cast<int32>(available * 8 / 10);
 118
 119   // Return kDefaultCacheSize if it uses 80% to 10% of the available space.
 120   if (available < kDefaultCacheSize * 10)
 121     return kDefaultCacheSize;
 122
 123   // Return 10% of the available space if the target size
 124   // (2.5 * kDefaultCacheSize) is more than 10%.
 125   if (available < static_cast<int64>(kDefaultCacheSize) * 25)
 126     return static_cast<int32>(available / 10);
 127
 128   // Return the target size (2.5 * kDefaultCacheSize) if it uses 10% to 1%
 129   // of the available space.
 130   if (available < static_cast<int64>(kDefaultCacheSize) * 250)
 131     return kDefaultCacheSize * 5 / 2;
 132
 133   // Return 1% of the available space if it does not exceed kint32max.
 134   if (available < static_cast<int64>(kint32max) * 100)
 135     return static_cast<int32>(available / 100);
 136
 137   return kint32max;
 138 }
 139
 140 // ------------------------------------------------------------------------
 141
 142 BackendImpl::BackendImpl(const base::FilePath& path,
 143                          base::MessageLoopProxy* cache_thread,
 144                          net::NetLog* net_log)
 145     : background_queue_(this, cache_thread),
 146       path_(path),
 147       block_files_(path),
 148       mask_(0),
 149       max_size_(0),
 150       up_ticks_(0),
 151       cache_type_(net::DISK_CACHE),
 152       uma_report_(0),
 153       user_flags_(0),
 154       init_(false),
 155       restarted_(false),
 156       unit_test_(false),
 157       read_only_(false),
 158       disabled_(false),
 159       new_eviction_(false),
 160       first_timer_(true),
 161       user_load_(false),
 162       net_log_(net_log),
 163       done_(true, false),
 164       ptr_factory_(this) {
 165 }
 166
 167 BackendImpl::BackendImpl(const base::FilePath& path,
 168                          uint32 mask,
 169                          base::MessageLoopProxy* cache_thread,
 170                          net::NetLog* net_log)
 171     : background_queue_(this, cache_thread),
 172       path_(path),
 173       block_files_(path),
 174       mask_(mask),
 175       max_size_(0),
 176       up_ticks_(0),
 177       cache_type_(net::DISK_CACHE),
 178       uma_report_(0),
 179       user_flags_(kMask),
 180       init_(false),
 181       restarted_(false),
 182       unit_test_(false),
 183       read_only_(false),
 184       disabled_(false),
 185       new_eviction_(false),
 186       first_timer_(true),
 187       user_load_(false),
 188       net_log_(net_log),
 189       done_(true, false),
 190       ptr_factory_(this) {
 191 }
 192
 193 BackendImpl::~BackendImpl() {
 194   if (user_flags_ & kNoRandom) {
 195     // This is a unit test, so we want to be strict about not leaking entries
 196     // and completing all the work.
 197     background_queue_.WaitForPendingIO();
 198   } else {
 199     // This is most likely not a test, so we want to do as little work as
 200     // possible at this time, at the price of leaving dirty entries behind.
 201     background_queue_.DropPendingIO();
 202   }
 203
 204   if (background_queue_.BackgroundIsCurrentThread()) {
 205     // Unit tests may use the same thread for everything.
 206     CleanupCache();
 207   } else {
 208     background_queue_.background_thread()->PostTask(
 209         FROM_HERE, base::Bind(&FinalCleanupCallback, base::Unretained(this)));
 210     // http://crbug.com/74623
 211     base::ThreadRestrictions::ScopedAllowWait allow_wait;
 212     done_.Wait();
 213   }
 214 }
 215
 216 int BackendImpl::Init(const CompletionCallback& callback) {
 217   background_queue_.Init(callback);
 218   return net::ERR_IO_PENDING;
 219 }
 220
 221 int BackendImpl::SyncInit() {
 222 #if defined(NET_BUILD_STRESS_CACHE)
 223   // Start evictions right away.
 224   up_ticks_ = kTrimDelay * 2;
 225 #endif
 226   DCHECK(!init_);
 227   if (init_)
 228     return net::ERR_FAILED;
 229
 230   bool create_files = false;
 231   if (!InitBackingStore(&create_files)) {
 232     ReportError(ERR_STORAGE_ERROR);
 233     return net::ERR_FAILED;
 234   }
 235
 236   num_refs_ = num_pending_io_ = max_refs_ = 0;
 237   entry_count_ = byte_count_ = 0;
 238
 239   if (!restarted_) {
 240     buffer_bytes_ = 0;
 241     trace_object_ = TraceObject::GetTraceObject();
 242     // Create a recurrent timer of 30 secs.
 243     int timer_delay = unit_test_ ? 1000 : 30000;
 244     timer_.reset(new base::RepeatingTimer<BackendImpl>());
 245     timer_->Start(FROM_HERE, TimeDelta::FromMilliseconds(timer_delay), this,
 246                   &BackendImpl::OnStatsTimer);
 247   }
 248
 249   init_ = true;
 250   Trace("Init");
 251
 252   if (data_->header.experiment != NO_EXPERIMENT &&
 253       cache_type_ != net::DISK_CACHE) {
 254     // No experiment for other caches.
 255     return net::ERR_FAILED;
 256   }
 257
 258   if (!(user_flags_ & kNoRandom)) {
 259     // The unit test controls directly what to test.
 260     new_eviction_ = (cache_type_ == net::DISK_CACHE);
 261   }
 262
 263   if (!CheckIndex()) {
 264     ReportError(ERR_INIT_FAILED);
 265     return net::ERR_FAILED;
 266   }
 267
 268   if (!restarted_ && (create_files || !data_->header.num_entries))
 269     ReportError(ERR_CACHE_CREATED);
 270
 271   if (!(user_flags_ & kNoRandom) && cache_type_ == net::DISK_CACHE &&
 272       !InitExperiment(&data_->header, create_files)) {
 273     return net::ERR_FAILED;
 274   }
 275
 276   // We don't care if the value overflows. The only thing we care about is that
 277   // the id cannot be zero, because that value is used as "not dirty".
 278   // Increasing the value once per second gives us many years before we start
 279   // having collisions.
 280   data_->header.this_id++;
 281   if (!data_->header.this_id)
 282     data_->header.this_id++;
 283
 284   bool previous_crash = (data_->header.crash != 0);
 285   data_->header.crash = 1;
 286
 287   if (!block_files_.Init(create_files))
 288     return net::ERR_FAILED;
 289
 290   // We want to minimize the changes to cache for an AppCache.
 291   if (cache_type() == net::APP_CACHE) {
 292     DCHECK(!new_eviction_);
 293     read_only_ = true;
 294   } else if (cache_type() == net::SHADER_CACHE) {
 295     DCHECK(!new_eviction_);
 296   }
 297
 298   eviction_.Init(this);
 299
 300   // stats_ and rankings_ may end up calling back to us so we better be enabled.
 301   disabled_ = false;
 302   if (!InitStats())
 303     return net::ERR_FAILED;
 304
 305   disabled_ = !rankings_.Init(this, new_eviction_);
 306
 307 #if defined(STRESS_CACHE_EXTENDED_VALIDATION)
 308   trace_object_->EnableTracing(false);
 309   int sc = SelfCheck();
 310   if (sc < 0 && sc != ERR_NUM_ENTRIES_MISMATCH)
 311     NOTREACHED();
 312   trace_object_->EnableTracing(true);
 313 #endif
 314
 315   if (previous_crash) {
 316     ReportError(ERR_PREVIOUS_CRASH);
 317   } else if (!restarted_) {
 318     ReportError(ERR_NO_ERROR);
 319   }
 320
 321   FlushIndex();
 322
 323   return disabled_ ? net::ERR_FAILED : net::OK;
 324 }
 325
 326 void BackendImpl::CleanupCache() {
 327   Trace("Backend Cleanup");
 328   eviction_.Stop();
 329   timer_.reset();
 330
 331   if (init_) {
 332     StoreStats();
 333     if (data_)
 334       data_->header.crash = 0;
 335
 336     if (user_flags_ & kNoRandom) {
 337       // This is a net_unittest, verify that we are not 'leaking' entries.
 338       File::WaitForPendingIO(&num_pending_io_);
 339       DCHECK(!num_refs_);
 340     } else {
 341       File::DropPendingIO();
 342     }
 343   }
 344   block_files_.CloseFiles();
 345   FlushIndex();
 346   index_ = NULL;
 347   ptr_factory_.InvalidateWeakPtrs();
 348   done_.Signal();
 349 }
 350
 351 // ------------------------------------------------------------------------
 352
 353 int BackendImpl::OpenPrevEntry(void** iter, Entry** prev_entry,
 354                                const CompletionCallback& callback) {
 355   DCHECK(!callback.is_null());
 356   background_queue_.OpenPrevEntry(iter, prev_entry, callback);
 357   return net::ERR_IO_PENDING;
 358 }
 359
 360 int BackendImpl::SyncOpenEntry(const std::string& key, Entry** entry) {
 361   DCHECK(entry);
 362   *entry = OpenEntryImpl(key);
 363   return (*entry) ? net::OK : net::ERR_FAILED;
 364 }
 365
 366 int BackendImpl::SyncCreateEntry(const std::string& key, Entry** entry) {
 367   DCHECK(entry);
 368   *entry = CreateEntryImpl(key);
 369   return (*entry) ? net::OK : net::ERR_FAILED;
 370 }
 371
 372 int BackendImpl::SyncDoomEntry(const std::string& key) {
 373   if (disabled_)
 374     return net::ERR_FAILED;
 375
 376   EntryImpl* entry = OpenEntryImpl(key);
 377   if (!entry)
 378     return net::ERR_FAILED;
 379
 380   entry->DoomImpl();
 381   entry->Release();
 382   return net::OK;
 383 }
 384
 385 int BackendImpl::SyncDoomAllEntries() {
 386   // This is not really an error, but it is an interesting condition.
 387   ReportError(ERR_CACHE_DOOMED);
 388   stats_.OnEvent(Stats::DOOM_CACHE);
 389   if (!num_refs_) {
 390     RestartCache(false);
 391     return disabled_ ? net::ERR_FAILED : net::OK;
 392   } else {
 393     if (disabled_)
 394       return net::ERR_FAILED;
 395
 396     eviction_.TrimCache(true);
 397     return net::OK;
 398   }
 399 }
 400
 401 int BackendImpl::SyncDoomEntriesBetween(const base::Time initial_time,
 402                                         const base::Time end_time) {
 403   DCHECK_NE(net::APP_CACHE, cache_type_);
 404   if (end_time.is_null())
 405     return SyncDoomEntriesSince(initial_time);
 406
 407   DCHECK(end_time >= initial_time);
 408
 409   if (disabled_)
 410     return net::ERR_FAILED;
 411
 412   EntryImpl* node;
 413   void* iter = NULL;
 414   EntryImpl* next = OpenNextEntryImpl(&iter);
 415   if (!next)
 416     return net::OK;
 417
 418   while (next) {
 419     node = next;
 420     next = OpenNextEntryImpl(&iter);
 421
 422     if (node->GetLastUsed() >= initial_time &&
 423         node->GetLastUsed() < end_time) {
 424       node->DoomImpl();
 425     } else if (node->GetLastUsed() < initial_time) {
 426       if (next)
 427         next->Release();
 428       next = NULL;
 429       SyncEndEnumeration(iter);
 430     }
 431
 432     node->Release();
 433   }
 434
 435   return net::OK;
 436 }
 437
 438 // We use OpenNextEntryImpl to retrieve elements from the cache, until we get
 439 // entries that are too old.
 440 int BackendImpl::SyncDoomEntriesSince(const base::Time initial_time) {
 441   DCHECK_NE(net::APP_CACHE, cache_type_);
 442   if (disabled_)
 443     return net::ERR_FAILED;
 444
 445   stats_.OnEvent(Stats::DOOM_RECENT);
 446   for (;;) {
 447     void* iter = NULL;
 448     EntryImpl* entry = OpenNextEntryImpl(&iter);
 449     if (!entry)
 450       return net::OK;
 451
 452     if (initial_time > entry->GetLastUsed()) {
 453       entry->Release();
 454       SyncEndEnumeration(iter);
 455       return net::OK;
 456     }
 457
 458     entry->DoomImpl();
 459     entry->Release();
 460     SyncEndEnumeration(iter);  // Dooming the entry invalidates the iterator.
 461   }
 462 }
 463
 464 int BackendImpl::SyncOpenNextEntry(void** iter, Entry** next_entry) {
 465   *next_entry = OpenNextEntryImpl(iter);
 466   return (*next_entry) ? net::OK : net::ERR_FAILED;
 467 }
 468
 469 int BackendImpl::SyncOpenPrevEntry(void** iter, Entry** prev_entry) {
 470   *prev_entry = OpenPrevEntryImpl(iter);
 471   return (*prev_entry) ? net::OK : net::ERR_FAILED;
 472 }
 473
 474 void BackendImpl::SyncEndEnumeration(void* iter) {
 475   scoped_ptr<Rankings::Iterator> iterator(
 476       reinterpret_cast<Rankings::Iterator*>(iter));
 477 }
 478
 479 void BackendImpl::SyncOnExternalCacheHit(const std::string& key) {
 480   if (disabled_)
 481     return;
 482
 483   uint32 hash = base::Hash(key);
 484   bool error;
 485   EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
 486   if (cache_entry) {
 487     if (ENTRY_NORMAL == cache_entry->entry()->Data()->state) {
 488       UpdateRank(cache_entry, cache_type() == net::SHADER_CACHE);
 489     }
 490     cache_entry->Release();
 491   }
 492 }
 493
 494 EntryImpl* BackendImpl::OpenEntryImpl(const std::string& key) {
 495   if (disabled_)
 496     return NULL;
 497
 498   TimeTicks start = TimeTicks::Now();
 499   uint32 hash = base::Hash(key);
 500   Trace("Open hash 0x%x", hash);
 501
 502   bool error;
 503   EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
 504   if (cache_entry && ENTRY_NORMAL != cache_entry->entry()->Data()->state) {
 505     // The entry was already evicted.
 506     cache_entry->Release();
 507     cache_entry = NULL;
 508   }
 509
 510   int current_size = data_->header.num_bytes / (1024 * 1024);
 511   int64 total_hours = stats_.GetCounter(Stats::TIMER) / 120;
 512   int64 no_use_hours = stats_.GetCounter(Stats::LAST_REPORT_TIMER) / 120;
 513   int64 use_hours = total_hours - no_use_hours;
 514
 515   if (!cache_entry) {
 516     CACHE_UMA(AGE_MS, "OpenTime.Miss", 0, start);
 517     CACHE_UMA(COUNTS_10000, "AllOpenBySize.Miss", 0, current_size);
 518     CACHE_UMA(HOURS, "AllOpenByTotalHours.Miss", 0, total_hours);
 519     CACHE_UMA(HOURS, "AllOpenByUseHours.Miss", 0, use_hours);
 520     stats_.OnEvent(Stats::OPEN_MISS);
 521     return NULL;
 522   }
 523
 524   eviction_.OnOpenEntry(cache_entry);
 525   entry_count_++;
 526
 527   Trace("Open hash 0x%x end: 0x%x", hash,
 528         cache_entry->entry()->address().value());
 529   CACHE_UMA(AGE_MS, "OpenTime", 0, start);
 530   CACHE_UMA(COUNTS_10000, "AllOpenBySize.Hit", 0, current_size);
 531   CACHE_UMA(HOURS, "AllOpenByTotalHours.Hit", 0, total_hours);
 532   CACHE_UMA(HOURS, "AllOpenByUseHours.Hit", 0, use_hours);
 533   stats_.OnEvent(Stats::OPEN_HIT);
 534   SIMPLE_STATS_COUNTER("disk_cache.hit");
 535   return cache_entry;
 536 }
 537
 538 EntryImpl* BackendImpl::CreateEntryImpl(const std::string& key) {
 539   if (disabled_ || key.empty())
 540     return NULL;
 541
 542   TimeTicks start = TimeTicks::Now();
 543   uint32 hash = base::Hash(key);
 544   Trace("Create hash 0x%x", hash);
 545
 546   scoped_refptr<EntryImpl> parent;
 547   Addr entry_address(data_->table[hash & mask_]);
 548   if (entry_address.is_initialized()) {
 549     // We have an entry already. It could be the one we are looking for, or just
 550     // a hash conflict.
 551     bool error;
 552     EntryImpl* old_entry = MatchEntry(key, hash, false, Addr(), &error);
 553     if (old_entry)
 554       return ResurrectEntry(old_entry);
 555
 556     EntryImpl* parent_entry = MatchEntry(key, hash, true, Addr(), &error);
 557     DCHECK(!error);
 558     if (parent_entry) {
 559       parent.swap(&parent_entry);
 560     } else if (data_->table[hash & mask_]) {
 561       // We should have corrected the problem.
 562       NOTREACHED();
 563       return NULL;
 564     }
 565   }
 566
 567   // The general flow is to allocate disk space and initialize the entry data,
 568   // followed by saving that to disk, then linking the entry though the index
 569   // and finally through the lists. If there is a crash in this process, we may
 570   // end up with:
 571   // a. Used, unreferenced empty blocks on disk (basically just garbage).
 572   // b. Used, unreferenced but meaningful data on disk (more garbage).
 573   // c. A fully formed entry, reachable only through the index.
 574   // d. A fully formed entry, also reachable through the lists, but still dirty.
 575   //
 576   // Anything after (b) can be automatically cleaned up. We may consider saving
 577   // the current operation (as we do while manipulating the lists) so that we
 578   // can detect and cleanup (a) and (b).
 579
 580   int num_blocks = EntryImpl::NumBlocksForEntry(key.size());
 581   if (!block_files_.CreateBlock(BLOCK_256, num_blocks, &entry_address)) {
 582     LOG(ERROR) << "Create entry failed " << key.c_str();
 583     stats_.OnEvent(Stats::CREATE_ERROR);
 584     return NULL;
 585   }
 586
 587   Addr node_address(0);
 588   if (!block_files_.CreateBlock(RANKINGS, 1, &node_address)) {
 589     block_files_.DeleteBlock(entry_address, false);
 590     LOG(ERROR) << "Create entry failed " << key.c_str();
 591     stats_.OnEvent(Stats::CREATE_ERROR);
 592     return NULL;
 593   }
 594
 595   scoped_refptr<EntryImpl> cache_entry(
 596       new EntryImpl(this, entry_address, false));
 597   IncreaseNumRefs();
 598
 599   if (!cache_entry->CreateEntry(node_address, key, hash)) {
 600     block_files_.DeleteBlock(entry_address, false);
 601     block_files_.DeleteBlock(node_address, false);
 602     LOG(ERROR) << "Create entry failed " << key.c_str();
 603     stats_.OnEvent(Stats::CREATE_ERROR);
 604     return NULL;
 605   }
 606
 607   cache_entry->BeginLogging(net_log_, true);
 608
 609   // We are not failing the operation; let's add this to the map.
 610   open_entries_[entry_address.value()] = cache_entry.get();
 611
 612   // Save the entry.
 613   cache_entry->entry()->Store();
 614   cache_entry->rankings()->Store();
 615   IncreaseNumEntries();
 616   entry_count_++;
 617
 618   // Link this entry through the index.
 619   if (parent.get()) {
 620     parent->SetNextAddress(entry_address);
 621   } else {
 622     data_->table[hash & mask_] = entry_address.value();
 623   }
 624
 625   // Link this entry through the lists.
 626   eviction_.OnCreateEntry(cache_entry.get());
 627
 628   CACHE_UMA(AGE_MS, "CreateTime", 0, start);
 629   stats_.OnEvent(Stats::CREATE_HIT);
 630   SIMPLE_STATS_COUNTER("disk_cache.miss");
 631   Trace("create entry hit ");
 632   FlushIndex();
 633   cache_entry->AddRef();
 634   return cache_entry.get();
 635 }
 636
 637 EntryImpl* BackendImpl::OpenNextEntryImpl(void** iter) {
 638   return OpenFollowingEntry(true, iter);
 639 }
 640
 641 EntryImpl* BackendImpl::OpenPrevEntryImpl(void** iter) {
 642   return OpenFollowingEntry(false, iter);
 643 }
 644
 645 bool BackendImpl::SetMaxSize(int max_bytes) {
 646   COMPILE_ASSERT(sizeof(max_bytes) == sizeof(max_size_), unsupported_int_model);
 647   if (max_bytes < 0)
 648     return false;
 649
 650   // Zero size means use the default.
 651   if (!max_bytes)
 652     return true;
 653
 654   // Avoid a DCHECK later on.
 655   if (max_bytes >= kint32max - kint32max / 10)
 656     max_bytes = kint32max - kint32max / 10 - 1;
 657
 658   user_flags_ |= kMaxSize;
 659   max_size_ = max_bytes;
 660   return true;
 661 }
 662
 663 void BackendImpl::SetType(net::CacheType type) {
 664   DCHECK_NE(net::MEMORY_CACHE, type);
 665   cache_type_ = type;
 666 }
 667
 668 base::FilePath BackendImpl::GetFileName(Addr address) const {
 669   if (!address.is_separate_file() || !address.is_initialized()) {
 670     NOTREACHED();
 671     return base::FilePath();
 672   }
 673
 674   std::string tmp = base::StringPrintf("f_%06x", address.FileNumber());
 675   return path_.AppendASCII(tmp);
 676 }
 677
 678 MappedFile* BackendImpl::File(Addr address) {
 679   if (disabled_)
 680     return NULL;
 681   return block_files_.GetFile(address);
 682 }
 683
 684 base::WeakPtr<InFlightBackendIO> BackendImpl::GetBackgroundQueue() {
 685   return background_queue_.GetWeakPtr();
 686 }
 687
 688 bool BackendImpl::CreateExternalFile(Addr* address) {
 689   int file_number = data_->header.last_file + 1;
 690   Addr file_address(0);
 691   bool success = false;
 692   for (int i = 0; i < 0x0fffffff; i++, file_number++) {
 693     if (!file_address.SetFileNumber(file_number)) {
 694       file_number = 1;
 695       continue;
 696     }
 697     base::FilePath name = GetFileName(file_address);
 698     int flags = base::PLATFORM_FILE_READ |
 699                 base::PLATFORM_FILE_WRITE |
 700                 base::PLATFORM_FILE_CREATE |
 701                 base::PLATFORM_FILE_EXCLUSIVE_WRITE;
 702     base::PlatformFileError error;
 703     scoped_refptr<disk_cache::File> file(new disk_cache::File(
 704         base::CreatePlatformFile(name, flags, NULL, &error)));
 705     if (!file->IsValid()) {
 706       if (error != base::PLATFORM_FILE_ERROR_EXISTS) {
 707         LOG(ERROR) << "Unable to create file: " << error;
 708         return false;
 709       }
 710       continue;
 711     }
 712
 713     success = true;
 714     break;
 715   }
 716
 717   DCHECK(success);
 718   if (!success)
 719     return false;
 720
 721   data_->header.last_file = file_number;
 722   address->set_value(file_address.value());
 723   return true;
 724 }
 725
 726 bool BackendImpl::CreateBlock(FileType block_type, int block_count,
 727                              Addr* block_address) {
 728   return block_files_.CreateBlock(block_type, block_count, block_address);
 729 }
 730
 731 void BackendImpl::DeleteBlock(Addr block_address, bool deep) {
 732   block_files_.DeleteBlock(block_address, deep);
 733 }
 734
 735 LruData* BackendImpl::GetLruData() {
 736   return &data_->header.lru;
 737 }
 738
 739 void BackendImpl::UpdateRank(EntryImpl* entry, bool modified) {
 740   if (read_only_ || (!modified && cache_type() == net::SHADER_CACHE))
 741     return;
 742   eviction_.UpdateRank(entry, modified);
 743 }
 744
 745 void BackendImpl::RecoveredEntry(CacheRankingsBlock* rankings) {
 746   Addr address(rankings->Data()->contents);
 747   EntryImpl* cache_entry = NULL;
 748   if (NewEntry(address, &cache_entry)) {
 749     STRESS_NOTREACHED();
 750     return;
 751   }
 752
 753   uint32 hash = cache_entry->GetHash();
 754   cache_entry->Release();
 755
 756   // Anything on the table means that this entry is there.
 757   if (data_->table[hash & mask_])
 758     return;
 759
 760   data_->table[hash & mask_] = address.value();
 761   FlushIndex();
 762 }
 763
 764 void BackendImpl::InternalDoomEntry(EntryImpl* entry) {
 765   uint32 hash = entry->GetHash();
 766   std::string key = entry->GetKey();
 767   Addr entry_addr = entry->entry()->address();
 768   bool error;
 769   EntryImpl* parent_entry = MatchEntry(key, hash, true, entry_addr, &error);
 770   CacheAddr child(entry->GetNextAddress());
 771
 772   Trace("Doom entry 0x%p", entry);
 773
 774   if (!entry->doomed()) {
 775     // We may have doomed this entry from within MatchEntry.
 776     eviction_.OnDoomEntry(entry);
 777     entry->InternalDoom();
 778     if (!new_eviction_) {
 779       DecreaseNumEntries();
 780     }
 781     stats_.OnEvent(Stats::DOOM_ENTRY);
 782   }
 783
 784   if (parent_entry) {
 785     parent_entry->SetNextAddress(Addr(child));
 786     parent_entry->Release();
 787   } else if (!error) {
 788     data_->table[hash & mask_] = child;
 789   }
 790
 791   FlushIndex();
 792 }
 793
 794 #if defined(NET_BUILD_STRESS_CACHE)
 795
 796 CacheAddr BackendImpl::GetNextAddr(Addr address) {
 797   EntriesMap::iterator it = open_entries_.find(address.value());
 798   if (it != open_entries_.end()) {
 799     EntryImpl* this_entry = it->second;
 800     return this_entry->GetNextAddress();
 801   }
 802   DCHECK(block_files_.IsValid(address));
 803   DCHECK(!address.is_separate_file() && address.file_type() == BLOCK_256);
 804
 805   CacheEntryBlock entry(File(address), address);
 806   CHECK(entry.Load());
 807   return entry.Data()->next;
 808 }
 809
 810 void BackendImpl::NotLinked(EntryImpl* entry) {
 811   Addr entry_addr = entry->entry()->address();
 812   uint32 i = entry->GetHash() & mask_;
 813   Addr address(data_->table[i]);
 814   if (!address.is_initialized())
 815     return;
 816
 817   for (;;) {
 818     DCHECK(entry_addr.value() != address.value());
 819     address.set_value(GetNextAddr(address));
 820     if (!address.is_initialized())
 821       break;
 822   }
 823 }
 824 #endif  // NET_BUILD_STRESS_CACHE
 825
 826 // An entry may be linked on the DELETED list for a while after being doomed.
 827 // This function is called when we want to remove it.
 828 void BackendImpl::RemoveEntry(EntryImpl* entry) {
 829 #if defined(NET_BUILD_STRESS_CACHE)
 830   NotLinked(entry);
 831 #endif
 832   if (!new_eviction_)
 833     return;
 834
 835   DCHECK_NE(ENTRY_NORMAL, entry->entry()->Data()->state);
 836
 837   Trace("Remove entry 0x%p", entry);
 838   eviction_.OnDestroyEntry(entry);
 839   DecreaseNumEntries();
 840 }
 841
 842 void BackendImpl::OnEntryDestroyBegin(Addr address) {
 843   EntriesMap::iterator it = open_entries_.find(address.value());
 844   if (it != open_entries_.end())
 845     open_entries_.erase(it);
 846 }
 847
 848 void BackendImpl::OnEntryDestroyEnd() {
 849   DecreaseNumRefs();
 850   if (data_->header.num_bytes > max_size_ && !read_only_ &&
 851       (up_ticks_ > kTrimDelay || user_flags_ & kNoRandom))
 852     eviction_.TrimCache(false);
 853 }
 854
 855 EntryImpl* BackendImpl::GetOpenEntry(CacheRankingsBlock* rankings) const {
 856   DCHECK(rankings->HasData());
 857   EntriesMap::const_iterator it =
 858       open_entries_.find(rankings->Data()->contents);
 859   if (it != open_entries_.end()) {
 860     // We have this entry in memory.
 861     return it->second;
 862   }
 863
 864   return NULL;
 865 }
 866
 867 int32 BackendImpl::GetCurrentEntryId() const {
 868   return data_->header.this_id;
 869 }
 870
 871 int BackendImpl::MaxFileSize() const {
 872   return max_size_ / 8;
 873 }
 874
 875 void BackendImpl::ModifyStorageSize(int32 old_size, int32 new_size) {
 876   if (disabled_ || old_size == new_size)
 877     return;
 878   if (old_size > new_size)
 879     SubstractStorageSize(old_size - new_size);
 880   else
 881     AddStorageSize(new_size - old_size);
 882
 883   FlushIndex();
 884
 885   // Update the usage statistics.
 886   stats_.ModifyStorageStats(old_size, new_size);
 887 }
 888
 889 void BackendImpl::TooMuchStorageRequested(int32 size) {
 890   stats_.ModifyStorageStats(0, size);
 891 }
 892
 893 bool BackendImpl::IsAllocAllowed(int current_size, int new_size) {
 894   DCHECK_GT(new_size, current_size);
 895   if (user_flags_ & kNoBuffering)
 896     return false;
 897
 898   int to_add = new_size - current_size;
 899   if (buffer_bytes_ + to_add > MaxBuffersSize())
 900     return false;
 901
 902   buffer_bytes_ += to_add;
 903   CACHE_UMA(COUNTS_50000, "BufferBytes", 0, buffer_bytes_ / 1024);
 904   return true;
 905 }
 906
 907 void BackendImpl::BufferDeleted(int size) {
 908   buffer_bytes_ -= size;
 909   DCHECK_GE(size, 0);
 910 }
 911
 912 bool BackendImpl::IsLoaded() const {
 913   CACHE_UMA(COUNTS, "PendingIO", 0, num_pending_io_);
 914   if (user_flags_ & kNoLoadProtection)
 915     return false;
 916
 917   return (num_pending_io_ > 5 || user_load_);
 918 }
 919
 920 std::string BackendImpl::HistogramName(const char* name, int experiment) const {
 921   if (!experiment)
 922     return base::StringPrintf("DiskCache.%d.%s", cache_type_, name);
 923   return base::StringPrintf("DiskCache.%d.%s_%d", cache_type_,
 924                             name, experiment);
 925 }
 926
 927 base::WeakPtr<BackendImpl> BackendImpl::GetWeakPtr() {
 928   return ptr_factory_.GetWeakPtr();
 929 }
 930
 931 // We want to remove biases from some histograms so we only send data once per
 932 // week.
 933 bool BackendImpl::ShouldReportAgain() {
 934   if (uma_report_)
 935     return uma_report_ == 2;
 936
 937   uma_report_++;
 938   int64 last_report = stats_.GetCounter(Stats::LAST_REPORT);
 939   Time last_time = Time::FromInternalValue(last_report);
 940   if (!last_report || (Time::Now() - last_time).InDays() >= 7) {
 941     stats_.SetCounter(Stats::LAST_REPORT, Time::Now().ToInternalValue());
 942     uma_report_++;
 943     return true;
 944   }
 945   return false;
 946 }
 947
 948 void BackendImpl::FirstEviction() {
 949   DCHECK(data_->header.create_time);
 950   if (!GetEntryCount())
 951     return;  // This is just for unit tests.
 952
 953   Time create_time = Time::FromInternalValue(data_->header.create_time);
 954   CACHE_UMA(AGE, "FillupAge", 0, create_time);
 955
 956   int64 use_time = stats_.GetCounter(Stats::TIMER);
 957   CACHE_UMA(HOURS, "FillupTime", 0, static_cast<int>(use_time / 120));
 958   CACHE_UMA(PERCENTAGE, "FirstHitRatio", 0, stats_.GetHitRatio());
 959
 960   if (!use_time)
 961     use_time = 1;
 962   CACHE_UMA(COUNTS_10000, "FirstEntryAccessRate", 0,
 963             static_cast<int>(data_->header.num_entries / use_time));
 964   CACHE_UMA(COUNTS, "FirstByteIORate", 0,
 965             static_cast<int>((data_->header.num_bytes / 1024) / use_time));
 966
 967   int avg_size = data_->header.num_bytes / GetEntryCount();
 968   CACHE_UMA(COUNTS, "FirstEntrySize", 0, avg_size);
 969
 970   int large_entries_bytes = stats_.GetLargeEntriesSize();
 971   int large_ratio = large_entries_bytes * 100 / data_->header.num_bytes;
 972   CACHE_UMA(PERCENTAGE, "FirstLargeEntriesRatio", 0, large_ratio);
 973
 974   if (new_eviction_) {
 975     CACHE_UMA(PERCENTAGE, "FirstResurrectRatio", 0, stats_.GetResurrectRatio());
 976     CACHE_UMA(PERCENTAGE, "FirstNoUseRatio", 0,
 977               data_->header.lru.sizes[0] * 100 / data_->header.num_entries);
 978     CACHE_UMA(PERCENTAGE, "FirstLowUseRatio", 0,
 979               data_->header.lru.sizes[1] * 100 / data_->header.num_entries);
 980     CACHE_UMA(PERCENTAGE, "FirstHighUseRatio", 0,
 981               data_->header.lru.sizes[2] * 100 / data_->header.num_entries);
 982   }
 983
 984   stats_.ResetRatios();
 985 }
 986
 987 void BackendImpl::CriticalError(int error) {
 988   STRESS_NOTREACHED();
 989   LOG(ERROR) << "Critical error found " << error;
 990   if (disabled_)
 991     return;
 992
 993   stats_.OnEvent(Stats::FATAL_ERROR);
 994   LogStats();
 995   ReportError(error);
 996
 997   // Setting the index table length to an invalid value will force re-creation
 998   // of the cache files.
 999   data_->header.table_len = 1;
1000   disabled_ = true;
1001
1002   if (!num_refs_)
1003     base::MessageLoop::current()->PostTask(
1004         FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
1005 }
1006
1007 void BackendImpl::ReportError(int error) {
1008   STRESS_DCHECK(!error || error == ERR_PREVIOUS_CRASH ||
1009                 error == ERR_CACHE_CREATED);
1010
1011   // We transmit positive numbers, instead of direct error codes.
1012   DCHECK_LE(error, 0);
1013   CACHE_UMA(CACHE_ERROR, "Error", 0, error * -1);
1014 }
1015
1016 void BackendImpl::OnEvent(Stats::Counters an_event) {
1017   stats_.OnEvent(an_event);
1018 }
1019
1020 void BackendImpl::OnRead(int32 bytes) {
1021   DCHECK_GE(bytes, 0);
1022   byte_count_ += bytes;
1023   if (byte_count_ < 0)
1024     byte_count_ = kint32max;
1025 }
1026
1027 void BackendImpl::OnWrite(int32 bytes) {
1028   // We use the same implementation as OnRead... just log the number of bytes.
1029   OnRead(bytes);
1030 }
1031
1032 void BackendImpl::OnStatsTimer() {
1033   stats_.OnEvent(Stats::TIMER);
1034   int64 time = stats_.GetCounter(Stats::TIMER);
1035   int64 current = stats_.GetCounter(Stats::OPEN_ENTRIES);
1036
1037   // OPEN_ENTRIES is a sampled average of the number of open entries, avoiding
1038   // the bias towards 0.
1039   if (num_refs_ && (current != num_refs_)) {
1040     int64 diff = (num_refs_ - current) / 50;
1041     if (!diff)
1042       diff = num_refs_ > current ? 1 : -1;
1043     current = current + diff;
1044     stats_.SetCounter(Stats::OPEN_ENTRIES, current);
1045     stats_.SetCounter(Stats::MAX_ENTRIES, max_refs_);
1046   }
1047
1048   CACHE_UMA(COUNTS, "NumberOfReferences", 0, num_refs_);
1049
1050   CACHE_UMA(COUNTS_10000, "EntryAccessRate", 0, entry_count_);
1051   CACHE_UMA(COUNTS, "ByteIORate", 0, byte_count_ / 1024);
1052
1053   // These values cover about 99.5% of the population (Oct 2011).
1054   user_load_ = (entry_count_ > 300 || byte_count_ > 7 * 1024 * 1024);
1055   entry_count_ = 0;
1056   byte_count_ = 0;
1057   up_ticks_++;
1058
1059   if (!data_)
1060     first_timer_ = false;
1061   if (first_timer_) {
1062     first_timer_ = false;
1063     if (ShouldReportAgain())
1064       ReportStats();
1065   }
1066
1067   // Save stats to disk at 5 min intervals.
1068   if (time % 10 == 0)
1069     StoreStats();
1070 }
1071
1072 void BackendImpl::IncrementIoCount() {
1073   num_pending_io_++;
1074 }
1075
1076 void BackendImpl::DecrementIoCount() {
1077   num_pending_io_--;
1078 }
1079
1080 void BackendImpl::SetUnitTestMode() {
1081   user_flags_ |= kUnitTestMode;
1082   unit_test_ = true;
1083 }
1084
1085 void BackendImpl::SetUpgradeMode() {
1086   user_flags_ |= kUpgradeMode;
1087   read_only_ = true;
1088 }
1089
1090 void BackendImpl::SetNewEviction() {
1091   user_flags_ |= kNewEviction;
1092   new_eviction_ = true;
1093 }
1094
1095 void BackendImpl::SetFlags(uint32 flags) {
1096   user_flags_ |= flags;
1097 }
1098
1099 void BackendImpl::ClearRefCountForTest() {
1100   num_refs_ = 0;
1101 }
1102
1103 int BackendImpl::FlushQueueForTest(const CompletionCallback& callback) {
1104   background_queue_.FlushQueue(callback);
1105   return net::ERR_IO_PENDING;
1106 }
1107
1108 int BackendImpl::RunTaskForTest(const base::Closure& task,
1109                                 const CompletionCallback& callback) {
1110   background_queue_.RunTask(task, callback);
1111   return net::ERR_IO_PENDING;
1112 }
1113
1114 void BackendImpl::TrimForTest(bool empty) {
1115   eviction_.SetTestMode();
1116   eviction_.TrimCache(empty);
1117 }
1118
1119 void BackendImpl::TrimDeletedListForTest(bool empty) {
1120   eviction_.SetTestMode();
1121   eviction_.TrimDeletedList(empty);
1122 }
1123
1124 int BackendImpl::SelfCheck() {
1125   if (!init_) {
1126     LOG(ERROR) << "Init failed";
1127     return ERR_INIT_FAILED;
1128   }
1129
1130   int num_entries = rankings_.SelfCheck();
1131   if (num_entries < 0) {
1132     LOG(ERROR) << "Invalid rankings list, error " << num_entries;
1133 #if !defined(NET_BUILD_STRESS_CACHE)
1134     return num_entries;
1135 #endif
1136   }
1137
1138   if (num_entries != data_->header.num_entries) {
1139     LOG(ERROR) << "Number of entries mismatch";
1140 #if !defined(NET_BUILD_STRESS_CACHE)
1141     return ERR_NUM_ENTRIES_MISMATCH;
1142 #endif
1143   }
1144
1145   return CheckAllEntries();
1146 }
1147
1148 void BackendImpl::FlushIndex() {
1149   if (index_.get() && !disabled_)
1150     index_->Flush();
1151 }
1152
1153 // ------------------------------------------------------------------------
1154
1155 net::CacheType BackendImpl::GetCacheType() const {
1156   return cache_type_;
1157 }
1158
1159 int32 BackendImpl::GetEntryCount() const {
1160   if (!index_.get() || disabled_)
1161     return 0;
1162   // num_entries includes entries already evicted.
1163   int32 not_deleted = data_->header.num_entries -
1164                       data_->header.lru.sizes[Rankings::DELETED];
1165
1166   if (not_deleted < 0) {
1167     NOTREACHED();
1168     not_deleted = 0;
1169   }
1170
1171   return not_deleted;
1172 }
1173
1174 int BackendImpl::OpenEntry(const std::string& key, Entry** entry,
1175                            const CompletionCallback& callback) {
1176   DCHECK(!callback.is_null());
1177   background_queue_.OpenEntry(key, entry, callback);
1178   return net::ERR_IO_PENDING;
1179 }
1180
1181 int BackendImpl::CreateEntry(const std::string& key, Entry** entry,
1182                              const CompletionCallback& callback) {
1183   DCHECK(!callback.is_null());
1184   background_queue_.CreateEntry(key, entry, callback);
1185   return net::ERR_IO_PENDING;
1186 }
1187
1188 int BackendImpl::DoomEntry(const std::string& key,
1189                            const CompletionCallback& callback) {
1190   DCHECK(!callback.is_null());
1191   background_queue_.DoomEntry(key, callback);
1192   return net::ERR_IO_PENDING;
1193 }
1194
1195 int BackendImpl::DoomAllEntries(const CompletionCallback& callback) {
1196   DCHECK(!callback.is_null());
1197   background_queue_.DoomAllEntries(callback);
1198   return net::ERR_IO_PENDING;
1199 }
1200
1201 int BackendImpl::DoomEntriesBetween(const base::Time initial_time,
1202                                     const base::Time end_time,
1203                                     const CompletionCallback& callback) {
1204   DCHECK(!callback.is_null());
1205   background_queue_.DoomEntriesBetween(initial_time, end_time, callback);
1206   return net::ERR_IO_PENDING;
1207 }
1208
1209 int BackendImpl::DoomEntriesSince(const base::Time initial_time,
1210                                   const CompletionCallback& callback) {
1211   DCHECK(!callback.is_null());
1212   background_queue_.DoomEntriesSince(initial_time, callback);
1213   return net::ERR_IO_PENDING;
1214 }
1215
1216 int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
1217                                const CompletionCallback& callback) {
1218   DCHECK(!callback.is_null());
1219   background_queue_.OpenNextEntry(iter, next_entry, callback);
1220   return net::ERR_IO_PENDING;
1221 }
1222
1223 void BackendImpl::EndEnumeration(void** iter) {
1224   background_queue_.EndEnumeration(*iter);
1225   *iter = NULL;
1226 }
1227
1228 void BackendImpl::GetStats(StatsItems* stats) {
1229   if (disabled_)
1230     return;
1231
1232   std::pair<std::string, std::string> item;
1233
1234   item.first = "Entries";
1235   item.second = base::StringPrintf("%d", data_->header.num_entries);
1236   stats->push_back(item);
1237
1238   item.first = "Pending IO";
1239   item.second = base::StringPrintf("%d", num_pending_io_);
1240   stats->push_back(item);
1241
1242   item.first = "Max size";
1243   item.second = base::StringPrintf("%d", max_size_);
1244   stats->push_back(item);
1245
1246   item.first = "Current size";
1247   item.second = base::StringPrintf("%d", data_->header.num_bytes);
1248   stats->push_back(item);
1249
1250   item.first = "Cache type";
1251   item.second = "Blockfile Cache";
1252   stats->push_back(item);
1253
1254   stats_.GetItems(stats);
1255 }
1256
1257 void BackendImpl::OnExternalCacheHit(const std::string& key) {
1258   background_queue_.OnExternalCacheHit(key);
1259 }
1260
1261 // ------------------------------------------------------------------------
1262
1263 // We just created a new file so we're going to write the header and set the
1264 // file length to include the hash table (zero filled).
1265 bool BackendImpl::CreateBackingStore(disk_cache::File* file) {
1266   AdjustMaxCacheSize(0);
1267
1268   IndexHeader header;
1269   header.table_len = DesiredIndexTableLen(max_size_);
1270
1271   // We need file version 2.1 for the new eviction algorithm.
1272   if (new_eviction_)
1273     header.version = 0x20001;
1274
1275   header.create_time = Time::Now().ToInternalValue();
1276
1277   if (!file->Write(&header, sizeof(header), 0))
1278     return false;
1279
1280   return file->SetLength(GetIndexSize(header.table_len));
1281 }
1282
1283 bool BackendImpl::InitBackingStore(bool* file_created) {
1284   if (!file_util::CreateDirectory(path_))
1285     return false;
1286
1287   base::FilePath index_name = path_.AppendASCII(kIndexName);
1288
1289   int flags = base::PLATFORM_FILE_READ |
1290               base::PLATFORM_FILE_WRITE |
1291               base::PLATFORM_FILE_OPEN_ALWAYS |
1292               base::PLATFORM_FILE_EXCLUSIVE_WRITE;
1293   scoped_refptr<disk_cache::File> file(new disk_cache::File(
1294       base::CreatePlatformFile(index_name, flags, file_created, NULL)));
1295
1296   if (!file->IsValid())
1297     return false;
1298
1299   bool ret = true;
1300   if (*file_created)
1301     ret = CreateBackingStore(file.get());
1302
1303   file = NULL;
1304   if (!ret)
1305     return false;
1306
1307   index_ = new MappedFile();
1308   data_ = reinterpret_cast<Index*>(index_->Init(index_name, 0));
1309   if (!data_) {
1310     LOG(ERROR) << "Unable to map Index file";
1311     return false;
1312   }
1313
1314   if (index_->GetLength() < sizeof(Index)) {
1315     // We verify this again on CheckIndex() but it's easier to make sure now
1316     // that the header is there.
1317     LOG(ERROR) << "Corrupt Index file";
1318     return false;
1319   }
1320
1321   return true;
1322 }
1323
1324 // The maximum cache size will be either set explicitly by the caller, or
1325 // calculated by this code.
1326 void BackendImpl::AdjustMaxCacheSize(int table_len) {
1327   if (max_size_)
1328     return;
1329
1330   // If table_len is provided, the index file exists.
1331   DCHECK(!table_len || data_->header.magic);
1332
1333   // The user is not setting the size, let's figure it out.
1334   int64 available = base::SysInfo::AmountOfFreeDiskSpace(path_);
1335   if (available < 0) {
1336     max_size_ = kDefaultCacheSize;
1337     return;
1338   }
1339
1340   if (table_len)
1341     available += data_->header.num_bytes;
1342
1343   max_size_ = PreferedCacheSize(available);
1344
1345   // Let's not use more than the default size while we tune-up the performance
1346   // of bigger caches. TODO(rvargas): remove this limit.
1347   if (max_size_ > kDefaultCacheSize * 4)
1348     max_size_ = kDefaultCacheSize * 4;
1349
1350   if (!table_len)
1351     return;
1352
1353   // If we already have a table, adjust the size to it.
1354   int current_max_size = MaxStorageSizeForTable(table_len);
1355   if (max_size_ > current_max_size)
1356     max_size_= current_max_size;
1357 }
1358
1359 bool BackendImpl::InitStats() {
1360   Addr address(data_->header.stats);
1361   int size = stats_.StorageSize();
1362
1363   if (!address.is_initialized()) {
1364     FileType file_type = Addr::RequiredFileType(size);
1365     DCHECK_NE(file_type, EXTERNAL);
1366     int num_blocks = Addr::RequiredBlocks(size, file_type);
1367
1368     if (!CreateBlock(file_type, num_blocks, &address))
1369       return false;
1370
1371     data_->header.stats = address.value();
1372     return stats_.Init(NULL, 0, address);
1373   }
1374
1375   if (!address.is_block_file()) {
1376     NOTREACHED();
1377     return false;
1378   }
1379
1380   // Load the required data.
1381   size = address.num_blocks() * address.BlockSize();
1382   MappedFile* file = File(address);
1383   if (!file)
1384     return false;
1385
1386   scoped_ptr<char[]> data(new char[size]);
1387   size_t offset = address.start_block() * address.BlockSize() +
1388                   kBlockHeaderSize;
1389   if (!file->Read(data.get(), size, offset))
1390     return false;
1391
1392   if (!stats_.Init(data.get(), size, address))
1393     return false;
1394   if (cache_type_ == net::DISK_CACHE && ShouldReportAgain())
1395     stats_.InitSizeHistogram();
1396   return true;
1397 }
1398
1399 void BackendImpl::StoreStats() {
1400   int size = stats_.StorageSize();
1401   scoped_ptr<char[]> data(new char[size]);
1402   Addr address;
1403   size = stats_.SerializeStats(data.get(), size, &address);
1404   DCHECK(size);
1405   if (!address.is_initialized())
1406     return;
1407
1408   MappedFile* file = File(address);
1409   if (!file)
1410     return;
1411
1412   size_t offset = address.start_block() * address.BlockSize() +
1413                   kBlockHeaderSize;
1414   file->Write(data.get(), size, offset);  // ignore result.
1415 }
1416
1417 void BackendImpl::RestartCache(bool failure) {
1418   int64 errors = stats_.GetCounter(Stats::FATAL_ERROR);
1419   int64 full_dooms = stats_.GetCounter(Stats::DOOM_CACHE);
1420   int64 partial_dooms = stats_.GetCounter(Stats::DOOM_RECENT);
1421   int64 last_report = stats_.GetCounter(Stats::LAST_REPORT);
1422
1423   PrepareForRestart();
1424   if (failure) {
1425     DCHECK(!num_refs_);
1426     DCHECK(!open_entries_.size());
1427     DelayedCacheCleanup(path_);
1428   } else {
1429     DeleteCache(path_, false);
1430   }
1431
1432   // Don't call Init() if directed by the unit test: we are simulating a failure
1433   // trying to re-enable the cache.
1434   if (unit_test_)
1435     init_ = true;  // Let the destructor do proper cleanup.
1436   else if (SyncInit() == net::OK) {
1437     stats_.SetCounter(Stats::FATAL_ERROR, errors);
1438     stats_.SetCounter(Stats::DOOM_CACHE, full_dooms);
1439     stats_.SetCounter(Stats::DOOM_RECENT, partial_dooms);
1440     stats_.SetCounter(Stats::LAST_REPORT, last_report);
1441   }
1442 }
1443
1444 void BackendImpl::PrepareForRestart() {
1445   // Reset the mask_ if it was not given by the user.
1446   if (!(user_flags_ & kMask))
1447     mask_ = 0;
1448
1449   if (!(user_flags_ & kNewEviction))
1450     new_eviction_ = false;
1451
1452   disabled_ = true;
1453   data_->header.crash = 0;
1454   index_->Flush();
1455   index_ = NULL;
1456   data_ = NULL;
1457   block_files_.CloseFiles();
1458   rankings_.Reset();
1459   init_ = false;
1460   restarted_ = true;
1461 }
1462
1463 int BackendImpl::NewEntry(Addr address, EntryImpl** entry) {
1464   EntriesMap::iterator it = open_entries_.find(address.value());
1465   if (it != open_entries_.end()) {
1466     // Easy job. This entry is already in memory.
1467     EntryImpl* this_entry = it->second;
1468     this_entry->AddRef();
1469     *entry = this_entry;
1470     return 0;
1471   }
1472
1473   STRESS_DCHECK(block_files_.IsValid(address));
1474
1475   if (!address.SanityCheckForEntryV2()) {
1476     LOG(WARNING) << "Wrong entry address.";
1477     STRESS_NOTREACHED();
1478     return ERR_INVALID_ADDRESS;
1479   }
1480
1481   scoped_refptr<EntryImpl> cache_entry(
1482       new EntryImpl(this, address, read_only_));
1483   IncreaseNumRefs();
1484   *entry = NULL;
1485
1486   TimeTicks start = TimeTicks::Now();
1487   if (!cache_entry->entry()->Load())
1488     return ERR_READ_FAILURE;
1489
1490   if (IsLoaded()) {
1491     CACHE_UMA(AGE_MS, "LoadTime", 0, start);
1492   }
1493
1494   if (!cache_entry->SanityCheck()) {
1495     LOG(WARNING) << "Messed up entry found.";
1496     STRESS_NOTREACHED();
1497     return ERR_INVALID_ENTRY;
1498   }
1499
1500   STRESS_DCHECK(block_files_.IsValid(
1501                     Addr(cache_entry->entry()->Data()->rankings_node)));
1502
1503   if (!cache_entry->LoadNodeAddress())
1504     return ERR_READ_FAILURE;
1505
1506   if (!rankings_.SanityCheck(cache_entry->rankings(), false)) {
1507     STRESS_NOTREACHED();
1508     cache_entry->SetDirtyFlag(0);
1509     // Don't remove this from the list (it is not linked properly). Instead,
1510     // break the link back to the entry because it is going away, and leave the
1511     // rankings node to be deleted if we find it through a list.
1512     rankings_.SetContents(cache_entry->rankings(), 0);
1513   } else if (!rankings_.DataSanityCheck(cache_entry->rankings(), false)) {
1514     STRESS_NOTREACHED();
1515     cache_entry->SetDirtyFlag(0);
1516     rankings_.SetContents(cache_entry->rankings(), address.value());
1517   }
1518
1519   if (!cache_entry->DataSanityCheck()) {
1520     LOG(WARNING) << "Messed up entry found.";
1521     cache_entry->SetDirtyFlag(0);
1522     cache_entry->FixForDelete();
1523   }
1524
1525   // Prevent overwriting the dirty flag on the destructor.
1526   cache_entry->SetDirtyFlag(GetCurrentEntryId());
1527
1528   if (cache_entry->dirty()) {
1529     Trace("Dirty entry 0x%p 0x%x", reinterpret_cast<void*>(cache_entry.get()),
1530           address.value());
1531   }
1532
1533   open_entries_[address.value()] = cache_entry.get();
1534
1535   cache_entry->BeginLogging(net_log_, false);
1536   cache_entry.swap(entry);
1537   return 0;
1538 }
1539
1540 EntryImpl* BackendImpl::MatchEntry(const std::string& key, uint32 hash,
1541                                    bool find_parent, Addr entry_addr,
1542                                    bool* match_error) {
1543   Addr address(data_->table[hash & mask_]);
1544   scoped_refptr<EntryImpl> cache_entry, parent_entry;
1545   EntryImpl* tmp = NULL;
1546   bool found = false;
1547   std::set<CacheAddr> visited;
1548   *match_error = false;
1549
1550   for (;;) {
1551     if (disabled_)
1552       break;
1553
1554     if (visited.find(address.value()) != visited.end()) {
1555       // It's possible for a buggy version of the code to write a loop. Just
1556       // break it.
1557       Trace("Hash collision loop 0x%x", address.value());
1558       address.set_value(0);
1559       parent_entry->SetNextAddress(address);
1560     }
1561     visited.insert(address.value());
1562
1563     if (!address.is_initialized()) {
1564       if (find_parent)
1565         found = true;
1566       break;
1567     }
1568
1569     int error = NewEntry(address, &tmp);
1570     cache_entry.swap(&tmp);
1571
1572     if (error || cache_entry->dirty()) {
1573       // This entry is dirty on disk (it was not properly closed): we cannot
1574       // trust it.
1575       Addr child(0);
1576       if (!error)
1577         child.set_value(cache_entry->GetNextAddress());
1578
1579       if (parent_entry.get()) {
1580         parent_entry->SetNextAddress(child);
1581         parent_entry = NULL;
1582       } else {
1583         data_->table[hash & mask_] = child.value();
1584       }
1585
1586       Trace("MatchEntry dirty %d 0x%x 0x%x", find_parent, entry_addr.value(),
1587             address.value());
1588
1589       if (!error) {
1590         // It is important to call DestroyInvalidEntry after removing this
1591         // entry from the table.
1592         DestroyInvalidEntry(cache_entry.get());
1593         cache_entry = NULL;
1594       } else {
1595         Trace("NewEntry failed on MatchEntry 0x%x", address.value());
1596       }
1597
1598       // Restart the search.
1599       address.set_value(data_->table[hash & mask_]);
1600       visited.clear();
1601       continue;
1602     }
1603
1604     DCHECK_EQ(hash & mask_, cache_entry->entry()->Data()->hash & mask_);
1605     if (cache_entry->IsSameEntry(key, hash)) {
1606       if (!cache_entry->Update())
1607         cache_entry = NULL;
1608       found = true;
1609       if (find_parent && entry_addr.value() != address.value()) {
1610         Trace("Entry not on the index 0x%x", address.value());
1611         *match_error = true;
1612         parent_entry = NULL;
1613       }
1614       break;
1615     }
1616     if (!cache_entry->Update())
1617       cache_entry = NULL;
1618     parent_entry = cache_entry;
1619     cache_entry = NULL;
1620     if (!parent_entry.get())
1621       break;
1622
1623     address.set_value(parent_entry->GetNextAddress());
1624   }
1625
1626   if (parent_entry.get() && (!find_parent || !found))
1627     parent_entry = NULL;
1628
1629   if (find_parent && entry_addr.is_initialized() && !cache_entry.get()) {
1630     *match_error = true;
1631     parent_entry = NULL;
1632   }
1633
1634   if (cache_entry.get() && (find_parent || !found))
1635     cache_entry = NULL;
1636
1637   find_parent ? parent_entry.swap(&tmp) : cache_entry.swap(&tmp);
1638   FlushIndex();
1639   return tmp;
1640 }
1641
1642 // This is the actual implementation for OpenNextEntry and OpenPrevEntry.
1643 EntryImpl* BackendImpl::OpenFollowingEntry(bool forward, void** iter) {
1644   if (disabled_)
1645     return NULL;
1646
1647   DCHECK(iter);
1648
1649   const int kListsToSearch = 3;
1650   scoped_refptr<EntryImpl> entries[kListsToSearch];
1651   scoped_ptr<Rankings::Iterator> iterator(
1652       reinterpret_cast<Rankings::Iterator*>(*iter));
1653   *iter = NULL;
1654
1655   if (!iterator.get()) {
1656     iterator.reset(new Rankings::Iterator(&rankings_));
1657     bool ret = false;
1658
1659     // Get an entry from each list.
1660     for (int i = 0; i < kListsToSearch; i++) {
1661       EntryImpl* temp = NULL;
1662       ret |= OpenFollowingEntryFromList(forward, static_cast<Rankings::List>(i),
1663                                         &iterator->nodes[i], &temp);
1664       entries[i].swap(&temp);  // The entry was already addref'd.
1665     }
1666     if (!ret)
1667       return NULL;
1668   } else {
1669     // Get the next entry from the last list, and the actual entries for the
1670     // elements on the other lists.
1671     for (int i = 0; i < kListsToSearch; i++) {
1672       EntryImpl* temp = NULL;
1673       if (iterator->list == i) {
1674           OpenFollowingEntryFromList(forward, iterator->list,
1675                                      &iterator->nodes[i], &temp);
1676       } else {
1677         temp = GetEnumeratedEntry(iterator->nodes[i],
1678                                   static_cast<Rankings::List>(i));
1679       }
1680
1681       entries[i].swap(&temp);  // The entry was already addref'd.
1682     }
1683   }
1684
1685   int newest = -1;
1686   int oldest = -1;
1687   Time access_times[kListsToSearch];
1688   for (int i = 0; i < kListsToSearch; i++) {
1689     if (entries[i].get()) {
1690       access_times[i] = entries[i]->GetLastUsed();
1691       if (newest < 0) {
1692         DCHECK_LT(oldest, 0);
1693         newest = oldest = i;
1694         continue;
1695       }
1696       if (access_times[i] > access_times[newest])
1697         newest = i;
1698       if (access_times[i] < access_times[oldest])
1699         oldest = i;
1700     }
1701   }
1702
1703   if (newest < 0 || oldest < 0)
1704     return NULL;
1705
1706   EntryImpl* next_entry;
1707   if (forward) {
1708     next_entry = entries[newest].get();
1709     iterator->list = static_cast<Rankings::List>(newest);
1710   } else {
1711     next_entry = entries[oldest].get();
1712     iterator->list = static_cast<Rankings::List>(oldest);
1713   }
1714
1715   *iter = iterator.release();
1716   next_entry->AddRef();
1717   return next_entry;
1718 }
1719
1720 bool BackendImpl::OpenFollowingEntryFromList(bool forward, Rankings::List list,
1721                                              CacheRankingsBlock** from_entry,
1722                                              EntryImpl** next_entry) {
1723   if (disabled_)
1724     return false;
1725
1726   if (!new_eviction_ && Rankings::NO_USE != list)
1727     return false;
1728
1729   Rankings::ScopedRankingsBlock rankings(&rankings_, *from_entry);
1730   CacheRankingsBlock* next_block = forward ?
1731       rankings_.GetNext(rankings.get(), list) :
1732       rankings_.GetPrev(rankings.get(), list);
1733   Rankings::ScopedRankingsBlock next(&rankings_, next_block);
1734   *from_entry = NULL;
1735
1736   *next_entry = GetEnumeratedEntry(next.get(), list);
1737   if (!*next_entry)
1738     return false;
1739
1740   *from_entry = next.release();
1741   return true;
1742 }
1743
1744 EntryImpl* BackendImpl::GetEnumeratedEntry(CacheRankingsBlock* next,
1745                                            Rankings::List list) {
1746   if (!next || disabled_)
1747     return NULL;
1748
1749   EntryImpl* entry;
1750   int rv = NewEntry(Addr(next->Data()->contents), &entry);
1751   if (rv) {
1752     STRESS_NOTREACHED();
1753     rankings_.Remove(next, list, false);
1754     if (rv == ERR_INVALID_ADDRESS) {
1755       // There is nothing linked from the index. Delete the rankings node.
1756       DeleteBlock(next->address(), true);
1757     }
1758     return NULL;
1759   }
1760
1761   if (entry->dirty()) {
1762     // We cannot trust this entry.
1763     InternalDoomEntry(entry);
1764     entry->Release();
1765     return NULL;
1766   }
1767
1768   if (!entry->Update()) {
1769     STRESS_NOTREACHED();
1770     entry->Release();
1771     return NULL;
1772   }
1773
1774   // Note that it is unfortunate (but possible) for this entry to be clean, but
1775   // not actually the real entry. In other words, we could have lost this entry
1776   // from the index, and it could have been replaced with a newer one. It's not
1777   // worth checking that this entry is "the real one", so we just return it and
1778   // let the enumeration continue; this entry will be evicted at some point, and
1779   // the regular path will work with the real entry. With time, this problem
1780   // will disasappear because this scenario is just a bug.
1781
1782   // Make sure that we save the key for later.
1783   entry->GetKey();
1784
1785   return entry;
1786 }
1787
1788 EntryImpl* BackendImpl::ResurrectEntry(EntryImpl* deleted_entry) {
1789   if (ENTRY_NORMAL == deleted_entry->entry()->Data()->state) {
1790     deleted_entry->Release();
1791     stats_.OnEvent(Stats::CREATE_MISS);
1792     Trace("create entry miss ");
1793     return NULL;
1794   }
1795
1796   // We are attempting to create an entry and found out that the entry was
1797   // previously deleted.
1798
1799   eviction_.OnCreateEntry(deleted_entry);
1800   entry_count_++;
1801
1802   stats_.OnEvent(Stats::RESURRECT_HIT);
1803   Trace("Resurrect entry hit ");
1804   return deleted_entry;
1805 }
1806
1807 void BackendImpl::DestroyInvalidEntry(EntryImpl* entry) {
1808   LOG(WARNING) << "Destroying invalid entry.";
1809   Trace("Destroying invalid entry 0x%p", entry);
1810
1811   entry->SetPointerForInvalidEntry(GetCurrentEntryId());
1812
1813   eviction_.OnDoomEntry(entry);
1814   entry->InternalDoom();
1815
1816   if (!new_eviction_)
1817     DecreaseNumEntries();
1818   stats_.OnEvent(Stats::INVALID_ENTRY);
1819 }
1820
1821 void BackendImpl::AddStorageSize(int32 bytes) {
1822   data_->header.num_bytes += bytes;
1823   DCHECK_GE(data_->header.num_bytes, 0);
1824 }
1825
1826 void BackendImpl::SubstractStorageSize(int32 bytes) {
1827   data_->header.num_bytes -= bytes;
1828   DCHECK_GE(data_->header.num_bytes, 0);
1829 }
1830
1831 void BackendImpl::IncreaseNumRefs() {
1832   num_refs_++;
1833   if (max_refs_ < num_refs_)
1834     max_refs_ = num_refs_;
1835 }
1836
1837 void BackendImpl::DecreaseNumRefs() {
1838   DCHECK(num_refs_);
1839   num_refs_--;
1840
1841   if (!num_refs_ && disabled_)
1842     base::MessageLoop::current()->PostTask(
1843         FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
1844 }
1845
1846 void BackendImpl::IncreaseNumEntries() {
1847   data_->header.num_entries++;
1848   DCHECK_GT(data_->header.num_entries, 0);
1849 }
1850
1851 void BackendImpl::DecreaseNumEntries() {
1852   data_->header.num_entries--;
1853   if (data_->header.num_entries < 0) {
1854     NOTREACHED();
1855     data_->header.num_entries = 0;
1856   }
1857 }
1858
1859 void BackendImpl::LogStats() {
1860   StatsItems stats;
1861   GetStats(&stats);
1862
1863   for (size_t index = 0; index < stats.size(); index++)
1864     VLOG(1) << stats[index].first << ": " << stats[index].second;
1865 }
1866
1867 void BackendImpl::ReportStats() {
1868   CACHE_UMA(COUNTS, "Entries", 0, data_->header.num_entries);
1869
1870   int current_size = data_->header.num_bytes / (1024 * 1024);
1871   int max_size = max_size_ / (1024 * 1024);
1872   int hit_ratio_as_percentage = stats_.GetHitRatio();
1873
1874   CACHE_UMA(COUNTS_10000, "Size2", 0, current_size);
1875   // For any bin in HitRatioBySize2, the hit ratio of caches of that size is the
1876   // ratio of that bin's total count to the count in the same bin in the Size2
1877   // histogram.
1878   if (base::RandInt(0, 99) < hit_ratio_as_percentage)
1879     CACHE_UMA(COUNTS_10000, "HitRatioBySize2", 0, current_size);
1880   CACHE_UMA(COUNTS_10000, "MaxSize2", 0, max_size);
1881   if (!max_size)
1882     max_size++;
1883   CACHE_UMA(PERCENTAGE, "UsedSpace", 0, current_size * 100 / max_size);
1884
1885   CACHE_UMA(COUNTS_10000, "AverageOpenEntries2", 0,
1886             static_cast<int>(stats_.GetCounter(Stats::OPEN_ENTRIES)));
1887   CACHE_UMA(COUNTS_10000, "MaxOpenEntries2", 0,
1888             static_cast<int>(stats_.GetCounter(Stats::MAX_ENTRIES)));
1889   stats_.SetCounter(Stats::MAX_ENTRIES, 0);
1890
1891   CACHE_UMA(COUNTS_10000, "TotalFatalErrors", 0,
1892             static_cast<int>(stats_.GetCounter(Stats::FATAL_ERROR)));
1893   CACHE_UMA(COUNTS_10000, "TotalDoomCache", 0,
1894             static_cast<int>(stats_.GetCounter(Stats::DOOM_CACHE)));
1895   CACHE_UMA(COUNTS_10000, "TotalDoomRecentEntries", 0,
1896             static_cast<int>(stats_.GetCounter(Stats::DOOM_RECENT)));
1897   stats_.SetCounter(Stats::FATAL_ERROR, 0);
1898   stats_.SetCounter(Stats::DOOM_CACHE, 0);
1899   stats_.SetCounter(Stats::DOOM_RECENT, 0);
1900
1901   int64 total_hours = stats_.GetCounter(Stats::TIMER) / 120;
1902   if (!data_->header.create_time || !data_->header.lru.filled) {
1903     int cause = data_->header.create_time ? 0 : 1;
1904     if (!data_->header.lru.filled)
1905       cause |= 2;
1906     CACHE_UMA(CACHE_ERROR, "ShortReport", 0, cause);
1907     CACHE_UMA(HOURS, "TotalTimeNotFull", 0, static_cast<int>(total_hours));
1908     return;
1909   }
1910
1911   // This is an up to date client that will report FirstEviction() data. After
1912   // that event, start reporting this:
1913
1914   CACHE_UMA(HOURS, "TotalTime", 0, static_cast<int>(total_hours));
1915   // For any bin in HitRatioByTotalTime, the hit ratio of caches of that total
1916   // time is the ratio of that bin's total count to the count in the same bin in
1917   // the TotalTime histogram.
1918   if (base::RandInt(0, 99) < hit_ratio_as_percentage)
1919     CACHE_UMA(HOURS, "HitRatioByTotalTime", 0, implicit_cast<int>(total_hours));
1920
1921   int64 use_hours = stats_.GetCounter(Stats::LAST_REPORT_TIMER) / 120;
1922   stats_.SetCounter(Stats::LAST_REPORT_TIMER, stats_.GetCounter(Stats::TIMER));
1923
1924   // We may see users with no use_hours at this point if this is the first time
1925   // we are running this code.
1926   if (use_hours)
1927     use_hours = total_hours - use_hours;
1928
1929   if (!use_hours || !GetEntryCount() || !data_->header.num_bytes)
1930     return;
1931
1932   CACHE_UMA(HOURS, "UseTime", 0, static_cast<int>(use_hours));
1933   // For any bin in HitRatioByUseTime, the hit ratio of caches of that use time
1934   // is the ratio of that bin's total count to the count in the same bin in the
1935   // UseTime histogram.
1936   if (base::RandInt(0, 99) < hit_ratio_as_percentage)
1937     CACHE_UMA(HOURS, "HitRatioByUseTime", 0, implicit_cast<int>(use_hours));
1938   CACHE_UMA(PERCENTAGE, "HitRatio", 0, hit_ratio_as_percentage);
1939
1940   int64 trim_rate = stats_.GetCounter(Stats::TRIM_ENTRY) / use_hours;
1941   CACHE_UMA(COUNTS, "TrimRate", 0, static_cast<int>(trim_rate));
1942
1943   int avg_size = data_->header.num_bytes / GetEntryCount();
1944   CACHE_UMA(COUNTS, "EntrySize", 0, avg_size);
1945   CACHE_UMA(COUNTS, "EntriesFull", 0, data_->header.num_entries);
1946
1947   CACHE_UMA(PERCENTAGE, "IndexLoad", 0,
1948             data_->header.num_entries * 100 / (mask_ + 1));
1949
1950   int large_entries_bytes = stats_.GetLargeEntriesSize();
1951   int large_ratio = large_entries_bytes * 100 / data_->header.num_bytes;
1952   CACHE_UMA(PERCENTAGE, "LargeEntriesRatio", 0, large_ratio);
1953
1954   if (new_eviction_) {
1955     CACHE_UMA(PERCENTAGE, "ResurrectRatio", 0, stats_.GetResurrectRatio());
1956     CACHE_UMA(PERCENTAGE, "NoUseRatio", 0,
1957               data_->header.lru.sizes[0] * 100 / data_->header.num_entries);
1958     CACHE_UMA(PERCENTAGE, "LowUseRatio", 0,
1959               data_->header.lru.sizes[1] * 100 / data_->header.num_entries);
1960     CACHE_UMA(PERCENTAGE, "HighUseRatio", 0,
1961               data_->header.lru.sizes[2] * 100 / data_->header.num_entries);
1962     CACHE_UMA(PERCENTAGE, "DeletedRatio", 0,
1963               data_->header.lru.sizes[4] * 100 / data_->header.num_entries);
1964   }
1965
1966   stats_.ResetRatios();
1967   stats_.SetCounter(Stats::TRIM_ENTRY, 0);
1968
1969   if (cache_type_ == net::DISK_CACHE)
1970     block_files_.ReportStats();
1971 }
1972
1973 void BackendImpl::UpgradeTo2_1() {
1974   // 2.1 is basically the same as 2.0, except that new fields are actually
1975   // updated by the new eviction algorithm.
1976   DCHECK(0x20000 == data_->header.version);
1977   data_->header.version = 0x20001;
1978   data_->header.lru.sizes[Rankings::NO_USE] = data_->header.num_entries;
1979 }
1980
1981 bool BackendImpl::CheckIndex() {
1982   DCHECK(data_);
1983
1984   size_t current_size = index_->GetLength();
1985   if (current_size < sizeof(Index)) {
1986     LOG(ERROR) << "Corrupt Index file";
1987     return false;
1988   }
1989
1990   if (new_eviction_) {
1991     // We support versions 2.0 and 2.1, upgrading 2.0 to 2.1.
1992     if (kIndexMagic != data_->header.magic ||
1993         kCurrentVersion >> 16 != data_->header.version >> 16) {
1994       LOG(ERROR) << "Invalid file version or magic";
1995       return false;
1996     }
1997     if (kCurrentVersion == data_->header.version) {
1998       // We need file version 2.1 for the new eviction algorithm.
1999       UpgradeTo2_1();
2000     }
2001   } else {
2002     if (kIndexMagic != data_->header.magic ||
2003         kCurrentVersion != data_->header.version) {
2004       LOG(ERROR) << "Invalid file version or magic";
2005       return false;
2006     }
2007   }
2008
2009   if (!data_->header.table_len) {
2010     LOG(ERROR) << "Invalid table size";
2011     return false;
2012   }
2013
2014   if (current_size < GetIndexSize(data_->header.table_len) ||
2015       data_->header.table_len & (kBaseTableLen - 1)) {
2016     LOG(ERROR) << "Corrupt Index file";
2017     return false;
2018   }
2019
2020   AdjustMaxCacheSize(data_->header.table_len);
2021
2022 #if !defined(NET_BUILD_STRESS_CACHE)
2023   if (data_->header.num_bytes < 0 ||
2024       (max_size_ < kint32max - kDefaultCacheSize &&
2025        data_->header.num_bytes > max_size_ + kDefaultCacheSize)) {
2026     LOG(ERROR) << "Invalid cache (current) size";
2027     return false;
2028   }
2029 #endif
2030
2031   if (data_->header.num_entries < 0) {
2032     LOG(ERROR) << "Invalid number of entries";
2033     return false;
2034   }
2035
2036   if (!mask_)
2037     mask_ = data_->header.table_len - 1;
2038
2039   // Load the table into memory with a single read.
2040   scoped_ptr<char[]> buf(new char[current_size]);
2041   return index_->Read(buf.get(), current_size, 0);
2042 }
2043
2044 int BackendImpl::CheckAllEntries() {
2045   int num_dirty = 0;
2046   int num_entries = 0;
2047   DCHECK(mask_ < kuint32max);
2048   for (unsigned int i = 0; i <= mask_; i++) {
2049     Addr address(data_->table[i]);
2050     if (!address.is_initialized())
2051       continue;
2052     for (;;) {
2053       EntryImpl* tmp;
2054       int ret = NewEntry(address, &tmp);
2055       if (ret) {
2056         STRESS_NOTREACHED();
2057         return ret;
2058       }
2059       scoped_refptr<EntryImpl> cache_entry;
2060       cache_entry.swap(&tmp);
2061
2062       if (cache_entry->dirty())
2063         num_dirty++;
2064       else if (CheckEntry(cache_entry.get()))
2065         num_entries++;
2066       else
2067         return ERR_INVALID_ENTRY;
2068
2069       DCHECK_EQ(i, cache_entry->entry()->Data()->hash & mask_);
2070       address.set_value(cache_entry->GetNextAddress());
2071       if (!address.is_initialized())
2072         break;
2073     }
2074   }
2075
2076   Trace("CheckAllEntries End");
2077   if (num_entries + num_dirty != data_->header.num_entries) {
2078     LOG(ERROR) << "Number of entries " << num_entries << " " << num_dirty <<
2079                   " " << data_->header.num_entries;
2080     DCHECK_LT(num_entries, data_->header.num_entries);
2081     return ERR_NUM_ENTRIES_MISMATCH;
2082   }
2083
2084   return num_dirty;
2085 }
2086
2087 bool BackendImpl::CheckEntry(EntryImpl* cache_entry) {
2088   bool ok = block_files_.IsValid(cache_entry->entry()->address());
2089   ok = ok && block_files_.IsValid(cache_entry->rankings()->address());
2090   EntryStore* data = cache_entry->entry()->Data();
2091   for (size_t i = 0; i < arraysize(data->data_addr); i++) {
2092     if (data->data_addr[i]) {
2093       Addr address(data->data_addr[i]);
2094       if (address.is_block_file())
2095         ok = ok && block_files_.IsValid(address);
2096     }
2097   }
2098
2099   return ok && cache_entry->rankings()->VerifyHash();
2100 }
2101
2102 int BackendImpl::MaxBuffersSize() {
2103   static int64 total_memory = base::SysInfo::AmountOfPhysicalMemory();
2104   static bool done = false;
2105
2106   if (!done) {
2107     const int kMaxBuffersSize = 30 * 1024 * 1024;
2108
2109     // We want to use up to 2% of the computer's memory.
2110     total_memory = total_memory * 2 / 100;
2111     if (total_memory > kMaxBuffersSize || total_memory <= 0)
2112       total_memory = kMaxBuffersSize;
2113
2114     done = true;
2115   }
2116
2117   return static_cast<int>(total_memory);
2118 }
2119
2120 }  // namespace disk_cache