Disk cache: Add base files for implementation of file format version 3.

net/disk_cache/v3/backend_impl_v3.cc

Index: net/disk_cache/v3/backend_impl_v3.cc
===================================================================
--- net/disk_cache/v3/backend_impl_v3.cc	(revision 0)
+++ net/disk_cache/v3/backend_impl_v3.cc	(working copy)
@@ -72,73 +72,12 @@
   return sizeof(disk_cache::IndexHeader) + table_size;
 }
 
-// ------------------------------------------------------------------------
-
-// Sets group for the current experiment. Returns false if the files should be
-// discarded.
-bool InitExperiment(disk_cache::IndexHeader* header, bool cache_created) {
-  if (header->experiment == disk_cache::EXPERIMENT_OLD_FILE1 ||
-      header->experiment == disk_cache::EXPERIMENT_OLD_FILE2) {
-    // Discard current cache.
-    return false;
-  }
-
-  if (base::FieldTrialList::FindFullName("SimpleCacheTrial") ==
-          "ExperimentControl") {
-    if (cache_created) {
-      header->experiment = disk_cache::EXPERIMENT_SIMPLE_CONTROL;
-      return true;
-    } else if (header->experiment != disk_cache::EXPERIMENT_SIMPLE_CONTROL) {
-      return false;
-    }
-  }
-
-  header->experiment = disk_cache::NO_EXPERIMENT;
-  return true;
-}
-
-// A callback to perform final cleanup on the background thread.
-void FinalCleanupCallback(disk_cache::BackendImpl* backend) {
-  backend->CleanupCache();
-}
-
 }  // namespace
 
 // ------------------------------------------------------------------------
 
 namespace disk_cache {
 
-// Returns the preferred maximum number of bytes for the cache given the
-// number of available bytes.
-int PreferedCacheSize(int64 available) {
-  // Return 80% of the available space if there is not enough space to use
-  // kDefaultCacheSize.
-  if (available < kDefaultCacheSize * 10 / 8)
-    return static_cast<int32>(available * 8 / 10);
-
-  // Return kDefaultCacheSize if it uses 80% to 10% of the available space.
-  if (available < kDefaultCacheSize * 10)
-    return kDefaultCacheSize;
-
-  // Return 10% of the available space if the target size
-  // (2.5 * kDefaultCacheSize) is more than 10%.
-  if (available < static_cast<int64>(kDefaultCacheSize) * 25)
-    return static_cast<int32>(available / 10);
-
-  // Return the target size (2.5 * kDefaultCacheSize) if it uses 10% to 1%
-  // of the available space.
-  if (available < static_cast<int64>(kDefaultCacheSize) * 250)
-    return kDefaultCacheSize * 5 / 2;
-
-  // Return 1% of the available space if it does not exceed kint32max.
-  if (available < static_cast<int64>(kint32max) * 100)
-    return static_cast<int32>(available / 100);
-
-  return kint32max;
-}
-
-// ------------------------------------------------------------------------
-
 BackendImpl::BackendImpl(const base::FilePath& path,
                          base::MessageLoopProxy* cache_thread,
                          net::NetLog* net_log)
@@ -218,136 +157,6 @@
   return net::ERR_IO_PENDING;
 }
 
-int BackendImpl::SyncInit() {
-#if defined(NET_BUILD_STRESS_CACHE)
-  // Start evictions right away.
-  up_ticks_ = kTrimDelay * 2;
-#endif
-  DCHECK(!init_);
-  if (init_)
-    return net::ERR_FAILED;
-
-  bool create_files = false;
-  if (!InitBackingStore(&create_files)) {
-    ReportError(ERR_STORAGE_ERROR);
-    return net::ERR_FAILED;
-  }
-
-  num_refs_ = num_pending_io_ = max_refs_ = 0;
-  entry_count_ = byte_count_ = 0;
-
-  if (!restarted_) {
-    buffer_bytes_ = 0;
-    trace_object_ = TraceObject::GetTraceObject();
-    // Create a recurrent timer of 30 secs.
-    int timer_delay = unit_test_ ? 1000 : 30000;
-    timer_.reset(new base::RepeatingTimer<BackendImpl>());
-    timer_->Start(FROM_HERE, TimeDelta::FromMilliseconds(timer_delay), this,
-                  &BackendImpl::OnStatsTimer);
-  }
-
-  init_ = true;
-  Trace("Init");
-
-  if (data_->header.experiment != NO_EXPERIMENT &&
-      cache_type_ != net::DISK_CACHE) {
-    // No experiment for other caches.
-    return net::ERR_FAILED;
-  }
-
-  if (!(user_flags_ & kNoRandom)) {
-    // The unit test controls directly what to test.
-    new_eviction_ = (cache_type_ == net::DISK_CACHE);
-  }
-
-  if (!CheckIndex()) {
-    ReportError(ERR_INIT_FAILED);
-    return net::ERR_FAILED;
-  }
-
-  if (!restarted_ && (create_files || !data_->header.num_entries))
-    ReportError(ERR_CACHE_CREATED);
-
-  if (!(user_flags_ & kNoRandom) && cache_type_ == net::DISK_CACHE &&
-      !InitExperiment(&data_->header, create_files)) {
-    return net::ERR_FAILED;
-  }
-
-  // We don't care if the value overflows. The only thing we care about is that
-  // the id cannot be zero, because that value is used as "not dirty".
-  // Increasing the value once per second gives us many years before we start
-  // having collisions.
-  data_->header.this_id++;
-  if (!data_->header.this_id)
-    data_->header.this_id++;
-
-  bool previous_crash = (data_->header.crash != 0);
-  data_->header.crash = 1;
-
-  if (!block_files_.Init(create_files))
-    return net::ERR_FAILED;
-
-  // We want to minimize the changes to cache for an AppCache.
-  if (cache_type() == net::APP_CACHE) {
-    DCHECK(!new_eviction_);
-    read_only_ = true;
-  } else if (cache_type() == net::SHADER_CACHE) {
-    DCHECK(!new_eviction_);
-  }
-
-  eviction_.Init(this);
-
-  // stats_ and rankings_ may end up calling back to us so we better be enabled.
-  disabled_ = false;
-  if (!InitStats())
-    return net::ERR_FAILED;
-
-  disabled_ = !rankings_.Init(this, new_eviction_);
-
-#if defined(STRESS_CACHE_EXTENDED_VALIDATION)
-  trace_object_->EnableTracing(false);
-  int sc = SelfCheck();
-  if (sc < 0 && sc != ERR_NUM_ENTRIES_MISMATCH)
-    NOTREACHED();
-  trace_object_->EnableTracing(true);
-#endif
-
-  if (previous_crash) {
-    ReportError(ERR_PREVIOUS_CRASH);
-  } else if (!restarted_) {
-    ReportError(ERR_NO_ERROR);
-  }
-
-  FlushIndex();
-
-  return disabled_ ? net::ERR_FAILED : net::OK;
-}
-
-void BackendImpl::CleanupCache() {
-  Trace("Backend Cleanup");
-  eviction_.Stop();
-  timer_.reset();
-
-  if (init_) {
-    StoreStats();
-    if (data_)
-      data_->header.crash = 0;
-
-    if (user_flags_ & kNoRandom) {
-      // This is a net_unittest, verify that we are not 'leaking' entries.
-      File::WaitForPendingIO(&num_pending_io_);
-      DCHECK(!num_refs_);
-    } else {
-      File::DropPendingIO();
-    }
-  }
-  block_files_.CloseFiles();
-  FlushIndex();
-  index_ = NULL;
-  ptr_factory_.InvalidateWeakPtrs();
-  done_.Signal();
-}
-
 // ------------------------------------------------------------------------
 
 int BackendImpl::OpenPrevEntry(void** iter, Entry** prev_entry,
@@ -357,291 +166,6 @@
   return net::ERR_IO_PENDING;
 }
 
-int BackendImpl::SyncOpenEntry(const std::string& key, Entry** entry) {
-  DCHECK(entry);
-  *entry = OpenEntryImpl(key);
-  return (*entry) ? net::OK : net::ERR_FAILED;
-}
-
-int BackendImpl::SyncCreateEntry(const std::string& key, Entry** entry) {
-  DCHECK(entry);
-  *entry = CreateEntryImpl(key);
-  return (*entry) ? net::OK : net::ERR_FAILED;
-}
-
-int BackendImpl::SyncDoomEntry(const std::string& key) {
-  if (disabled_)
-    return net::ERR_FAILED;
-
-  EntryImpl* entry = OpenEntryImpl(key);
-  if (!entry)
-    return net::ERR_FAILED;
-
-  entry->DoomImpl();
-  entry->Release();
-  return net::OK;
-}
-
-int BackendImpl::SyncDoomAllEntries() {
-  // This is not really an error, but it is an interesting condition.
-  ReportError(ERR_CACHE_DOOMED);
-  stats_.OnEvent(Stats::DOOM_CACHE);
-  if (!num_refs_) {
-    RestartCache(false);
-    return disabled_ ? net::ERR_FAILED : net::OK;
-  } else {
-    if (disabled_)
-      return net::ERR_FAILED;
-
-    eviction_.TrimCache(true);
-    return net::OK;
-  }
-}
-
-int BackendImpl::SyncDoomEntriesBetween(const base::Time initial_time,
-                                        const base::Time end_time) {
-  DCHECK_NE(net::APP_CACHE, cache_type_);
-  if (end_time.is_null())
-    return SyncDoomEntriesSince(initial_time);
-
-  DCHECK(end_time >= initial_time);
-
-  if (disabled_)
-    return net::ERR_FAILED;
-
-  EntryImpl* node;
-  void* iter = NULL;
-  EntryImpl* next = OpenNextEntryImpl(&iter);
-  if (!next)
-    return net::OK;
-
-  while (next) {
-    node = next;
-    next = OpenNextEntryImpl(&iter);
-
-    if (node->GetLastUsed() >= initial_time &&
-        node->GetLastUsed() < end_time) {
-      node->DoomImpl();
-    } else if (node->GetLastUsed() < initial_time) {
-      if (next)
-        next->Release();
-      next = NULL;
-      SyncEndEnumeration(iter);
-    }
-
-    node->Release();
-  }
-
-  return net::OK;
-}
-
-// We use OpenNextEntryImpl to retrieve elements from the cache, until we get
-// entries that are too old.
-int BackendImpl::SyncDoomEntriesSince(const base::Time initial_time) {
-  DCHECK_NE(net::APP_CACHE, cache_type_);
-  if (disabled_)
-    return net::ERR_FAILED;
-
-  stats_.OnEvent(Stats::DOOM_RECENT);
-  for (;;) {
-    void* iter = NULL;
-    EntryImpl* entry = OpenNextEntryImpl(&iter);
-    if (!entry)
-      return net::OK;
-
-    if (initial_time > entry->GetLastUsed()) {
-      entry->Release();
-      SyncEndEnumeration(iter);
-      return net::OK;
-    }
-
-    entry->DoomImpl();
-    entry->Release();
-    SyncEndEnumeration(iter);  // Dooming the entry invalidates the iterator.
-  }
-}
-
-int BackendImpl::SyncOpenNextEntry(void** iter, Entry** next_entry) {
-  *next_entry = OpenNextEntryImpl(iter);
-  return (*next_entry) ? net::OK : net::ERR_FAILED;
-}
-
-int BackendImpl::SyncOpenPrevEntry(void** iter, Entry** prev_entry) {
-  *prev_entry = OpenPrevEntryImpl(iter);
-  return (*prev_entry) ? net::OK : net::ERR_FAILED;
-}
-
-void BackendImpl::SyncEndEnumeration(void* iter) {
-  scoped_ptr<Rankings::Iterator> iterator(
-      reinterpret_cast<Rankings::Iterator*>(iter));
-}
-
-void BackendImpl::SyncOnExternalCacheHit(const std::string& key) {
-  if (disabled_)
-    return;
-
-  uint32 hash = base::Hash(key);
-  bool error;
-  EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
-  if (cache_entry) {
-    if (ENTRY_NORMAL == cache_entry->entry()->Data()->state) {
-      UpdateRank(cache_entry, cache_type() == net::SHADER_CACHE);
-    }
-    cache_entry->Release();
-  }
-}
-
-EntryImpl* BackendImpl::OpenEntryImpl(const std::string& key) {
-  if (disabled_)
-    return NULL;
-
-  TimeTicks start = TimeTicks::Now();
-  uint32 hash = base::Hash(key);
-  Trace("Open hash 0x%x", hash);
-
-  bool error;
-  EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
-  if (cache_entry && ENTRY_NORMAL != cache_entry->entry()->Data()->state) {
-    // The entry was already evicted.
-    cache_entry->Release();
-    cache_entry = NULL;
-  }
-
-  int current_size = data_->header.num_bytes / (1024 * 1024);
-  int64 total_hours = stats_.GetCounter(Stats::TIMER) / 120;
-  int64 no_use_hours = stats_.GetCounter(Stats::LAST_REPORT_TIMER) / 120;
-  int64 use_hours = total_hours - no_use_hours;
-
-  if (!cache_entry) {
-    CACHE_UMA(AGE_MS, "OpenTime.Miss", 0, start);
-    CACHE_UMA(COUNTS_10000, "AllOpenBySize.Miss", 0, current_size);
-    CACHE_UMA(HOURS, "AllOpenByTotalHours.Miss", 0, total_hours);
-    CACHE_UMA(HOURS, "AllOpenByUseHours.Miss", 0, use_hours);
-    stats_.OnEvent(Stats::OPEN_MISS);
-    return NULL;
-  }
-
-  eviction_.OnOpenEntry(cache_entry);
-  entry_count_++;
-
-  Trace("Open hash 0x%x end: 0x%x", hash,
-        cache_entry->entry()->address().value());
-  CACHE_UMA(AGE_MS, "OpenTime", 0, start);
-  CACHE_UMA(COUNTS_10000, "AllOpenBySize.Hit", 0, current_size);
-  CACHE_UMA(HOURS, "AllOpenByTotalHours.Hit", 0, total_hours);
-  CACHE_UMA(HOURS, "AllOpenByUseHours.Hit", 0, use_hours);
-  stats_.OnEvent(Stats::OPEN_HIT);
-  SIMPLE_STATS_COUNTER("disk_cache.hit");
-  return cache_entry;
-}
-
-EntryImpl* BackendImpl::CreateEntryImpl(const std::string& key) {
-  if (disabled_ || key.empty())
-    return NULL;
-
-  TimeTicks start = TimeTicks::Now();
-  uint32 hash = base::Hash(key);
-  Trace("Create hash 0x%x", hash);
-
-  scoped_refptr<EntryImpl> parent;
-  Addr entry_address(data_->table[hash & mask_]);
-  if (entry_address.is_initialized()) {
-    // We have an entry already. It could be the one we are looking for, or just
-    // a hash conflict.
-    bool error;
-    EntryImpl* old_entry = MatchEntry(key, hash, false, Addr(), &error);
-    if (old_entry)
-      return ResurrectEntry(old_entry);
-
-    EntryImpl* parent_entry = MatchEntry(key, hash, true, Addr(), &error);
-    DCHECK(!error);
-    if (parent_entry) {
-      parent.swap(&parent_entry);
-    } else if (data_->table[hash & mask_]) {
-      // We should have corrected the problem.
-      NOTREACHED();
-      return NULL;
-    }
-  }
-
-  // The general flow is to allocate disk space and initialize the entry data,
-  // followed by saving that to disk, then linking the entry though the index
-  // and finally through the lists. If there is a crash in this process, we may
-  // end up with:
-  // a. Used, unreferenced empty blocks on disk (basically just garbage).
-  // b. Used, unreferenced but meaningful data on disk (more garbage).
-  // c. A fully formed entry, reachable only through the index.
-  // d. A fully formed entry, also reachable through the lists, but still dirty.
-  //
-  // Anything after (b) can be automatically cleaned up. We may consider saving
-  // the current operation (as we do while manipulating the lists) so that we
-  // can detect and cleanup (a) and (b).
-
-  int num_blocks = EntryImpl::NumBlocksForEntry(key.size());
-  if (!block_files_.CreateBlock(BLOCK_256, num_blocks, &entry_address)) {
-    LOG(ERROR) << "Create entry failed " << key.c_str();
-    stats_.OnEvent(Stats::CREATE_ERROR);
-    return NULL;
-  }
-
-  Addr node_address(0);
-  if (!block_files_.CreateBlock(RANKINGS, 1, &node_address)) {
-    block_files_.DeleteBlock(entry_address, false);
-    LOG(ERROR) << "Create entry failed " << key.c_str();
-    stats_.OnEvent(Stats::CREATE_ERROR);
-    return NULL;
-  }
-
-  scoped_refptr<EntryImpl> cache_entry(
-      new EntryImpl(this, entry_address, false));
-  IncreaseNumRefs();
-
-  if (!cache_entry->CreateEntry(node_address, key, hash)) {
-    block_files_.DeleteBlock(entry_address, false);
-    block_files_.DeleteBlock(node_address, false);
-    LOG(ERROR) << "Create entry failed " << key.c_str();
-    stats_.OnEvent(Stats::CREATE_ERROR);
-    return NULL;
-  }
-
-  cache_entry->BeginLogging(net_log_, true);
-
-  // We are not failing the operation; let's add this to the map.
-  open_entries_[entry_address.value()] = cache_entry.get();
-
-  // Save the entry.
-  cache_entry->entry()->Store();
-  cache_entry->rankings()->Store();
-  IncreaseNumEntries();
-  entry_count_++;
-
-  // Link this entry through the index.
-  if (parent.get()) {
-    parent->SetNextAddress(entry_address);
-  } else {
-    data_->table[hash & mask_] = entry_address.value();
-  }
-
-  // Link this entry through the lists.
-  eviction_.OnCreateEntry(cache_entry.get());
-
-  CACHE_UMA(AGE_MS, "CreateTime", 0, start);
-  stats_.OnEvent(Stats::CREATE_HIT);
-  SIMPLE_STATS_COUNTER("disk_cache.miss");
-  Trace("create entry hit ");
-  FlushIndex();
-  cache_entry->AddRef();
-  return cache_entry.get();
-}
-
-EntryImpl* BackendImpl::OpenNextEntryImpl(void** iter) {
-  return OpenFollowingEntry(true, iter);
-}
-
-EntryImpl* BackendImpl::OpenPrevEntryImpl(void** iter) {
-  return OpenFollowingEntry(false, iter);
-}
-
 bool BackendImpl::SetMaxSize(int max_bytes) {
   COMPILE_ASSERT(sizeof(max_bytes) == sizeof(max_size_), unsupported_int_model);
   if (max_bytes < 0)
@@ -665,102 +189,17 @@
   cache_type_ = type;
 }
 
-base::FilePath BackendImpl::GetFileName(Addr address) const {
-  if (!address.is_separate_file() || !address.is_initialized()) {
-    NOTREACHED();
-    return base::FilePath();
-  }
-
-  std::string tmp = base::StringPrintf("f_%06x", address.FileNumber());
-  return path_.AppendASCII(tmp);
-}
-
-MappedFile* BackendImpl::File(Addr address) {
-  if (disabled_)
-    return NULL;
-  return block_files_.GetFile(address);
-}
-
-base::WeakPtr<InFlightBackendIO> BackendImpl::GetBackgroundQueue() {
-  return background_queue_.GetWeakPtr();
-}
-
-bool BackendImpl::CreateExternalFile(Addr* address) {
-  int file_number = data_->header.last_file + 1;
-  Addr file_address(0);
-  bool success = false;
-  for (int i = 0; i < 0x0fffffff; i++, file_number++) {
-    if (!file_address.SetFileNumber(file_number)) {
-      file_number = 1;
-      continue;
-    }
-    base::FilePath name = GetFileName(file_address);
-    int flags = base::PLATFORM_FILE_READ |
-                base::PLATFORM_FILE_WRITE |
-                base::PLATFORM_FILE_CREATE |
-                base::PLATFORM_FILE_EXCLUSIVE_WRITE;
-    base::PlatformFileError error;
-    scoped_refptr<disk_cache::File> file(new disk_cache::File(
-        base::CreatePlatformFile(name, flags, NULL, &error)));
-    if (!file->IsValid()) {
-      if (error != base::PLATFORM_FILE_ERROR_EXISTS) {
-        LOG(ERROR) << "Unable to create file: " << error;
-        return false;
-      }
-      continue;
-    }
-
-    success = true;
-    break;
-  }
-
-  DCHECK(success);
-  if (!success)
-    return false;
-
-  data_->header.last_file = file_number;
-  address->set_value(file_address.value());
-  return true;
-}
-
 bool BackendImpl::CreateBlock(FileType block_type, int block_count,
                              Addr* block_address) {
   return block_files_.CreateBlock(block_type, block_count, block_address);
 }
 
-void BackendImpl::DeleteBlock(Addr block_address, bool deep) {
-  block_files_.DeleteBlock(block_address, deep);
-}
-
-LruData* BackendImpl::GetLruData() {
-  return &data_->header.lru;
-}
-
 void BackendImpl::UpdateRank(EntryImpl* entry, bool modified) {
   if (read_only_ || (!modified && cache_type() == net::SHADER_CACHE))
     return;
   eviction_.UpdateRank(entry, modified);
 }
 
-void BackendImpl::RecoveredEntry(CacheRankingsBlock* rankings) {
-  Addr address(rankings->Data()->contents);
-  EntryImpl* cache_entry = NULL;
-  if (NewEntry(address, &cache_entry)) {
-    STRESS_NOTREACHED();
-    return;
-  }
-
-  uint32 hash = cache_entry->GetHash();
-  cache_entry->Release();
-
-  // Anything on the table means that this entry is there.
-  if (data_->table[hash & mask_])
-    return;
-
-  data_->table[hash & mask_] = address.value();
-  FlushIndex();
-}
-
 void BackendImpl::InternalDoomEntry(EntryImpl* entry) {
   uint32 hash = entry->GetHash();
   std::string key = entry->GetKey();
@@ -791,54 +230,6 @@
   FlushIndex();
 }
 
-#if defined(NET_BUILD_STRESS_CACHE)
-
-CacheAddr BackendImpl::GetNextAddr(Addr address) {
-  EntriesMap::iterator it = open_entries_.find(address.value());
-  if (it != open_entries_.end()) {
-    EntryImpl* this_entry = it->second;
-    return this_entry->GetNextAddress();
-  }
-  DCHECK(block_files_.IsValid(address));
-  DCHECK(!address.is_separate_file() && address.file_type() == BLOCK_256);
-
-  CacheEntryBlock entry(File(address), address);
-  CHECK(entry.Load());
-  return entry.Data()->next;
-}
-
-void BackendImpl::NotLinked(EntryImpl* entry) {
-  Addr entry_addr = entry->entry()->address();
-  uint32 i = entry->GetHash() & mask_;
-  Addr address(data_->table[i]);
-  if (!address.is_initialized())
-    return;
-
-  for (;;) {
-    DCHECK(entry_addr.value() != address.value());
-    address.set_value(GetNextAddr(address));
-    if (!address.is_initialized())
-      break;
-  }
-}
-#endif  // NET_BUILD_STRESS_CACHE
-
-// An entry may be linked on the DELETED list for a while after being doomed.
-// This function is called when we want to remove it.
-void BackendImpl::RemoveEntry(EntryImpl* entry) {
-#if defined(NET_BUILD_STRESS_CACHE)
-  NotLinked(entry);
-#endif
-  if (!new_eviction_)
-    return;
-
-  DCHECK_NE(ENTRY_NORMAL, entry->entry()->Data()->state);
-
-  Trace("Remove entry 0x%p", entry);
-  eviction_.OnDestroyEntry(entry);
-  DecreaseNumEntries();
-}
-
 void BackendImpl::OnEntryDestroyBegin(Addr address) {
   EntriesMap::iterator it = open_entries_.find(address.value());
   if (it != open_entries_.end())
@@ -864,10 +255,6 @@
   return NULL;
 }
 
-int32 BackendImpl::GetCurrentEntryId() const {
-  return data_->header.this_id;
-}
-
 int BackendImpl::MaxFileSize() const {
   return max_size_ / 8;
 }
@@ -984,35 +371,6 @@
   stats_.ResetRatios();
 }
 
-void BackendImpl::CriticalError(int error) {
-  STRESS_NOTREACHED();
-  LOG(ERROR) << "Critical error found " << error;
-  if (disabled_)
-    return;
-
-  stats_.OnEvent(Stats::FATAL_ERROR);
-  LogStats();
-  ReportError(error);
-
-  // Setting the index table length to an invalid value will force re-creation
-  // of the cache files.
-  data_->header.table_len = 1;
-  disabled_ = true;
-
-  if (!num_refs_)
-    base::MessageLoop::current()->PostTask(
-        FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
-}
-
-void BackendImpl::ReportError(int error) {
-  STRESS_DCHECK(!error || error == ERR_PREVIOUS_CRASH ||
-                error == ERR_CACHE_CREATED);
-
-  // We transmit positive numbers, instead of direct error codes.
-  DCHECK_LE(error, 0);
-  CACHE_UMA(CACHE_ERROR, "Error", 0, error * -1);
-}
-
 void BackendImpl::OnEvent(Stats::Counters an_event) {
   stats_.OnEvent(an_event);
 }
@@ -1069,14 +427,6 @@
     StoreStats();
 }
 
-void BackendImpl::IncrementIoCount() {
-  num_pending_io_++;
-}
-
-void BackendImpl::DecrementIoCount() {
-  num_pending_io_--;
-}
-
 void BackendImpl::SetUnitTestMode() {
   user_flags_ |= kUnitTestMode;
   unit_test_ = true;
@@ -1096,21 +446,11 @@
   user_flags_ |= flags;
 }
 
-void BackendImpl::ClearRefCountForTest() {
-  num_refs_ = 0;
-}
-
 int BackendImpl::FlushQueueForTest(const CompletionCallback& callback) {
   background_queue_.FlushQueue(callback);
   return net::ERR_IO_PENDING;
 }
 
-int BackendImpl::RunTaskForTest(const base::Closure& task,
-                                const CompletionCallback& callback) {
-  background_queue_.RunTask(task, callback);
-  return net::ERR_IO_PENDING;
-}
-
 void BackendImpl::TrimForTest(bool empty) {
   eviction_.SetTestMode();
   eviction_.TrimCache(empty);
@@ -1145,11 +485,6 @@
   return CheckAllEntries();
 }
 
-void BackendImpl::FlushIndex() {
-  if (index_.get() && !disabled_)
-    index_->Flush();
-}
-
 // ------------------------------------------------------------------------
 
 net::CacheType BackendImpl::GetCacheType() const {
@@ -1171,46 +506,238 @@
   return not_deleted;
 }
 
-int BackendImpl::OpenEntry(const std::string& key, Entry** entry,
-                           const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.OpenEntry(key, entry, callback);
-  return net::ERR_IO_PENDING;
+EntryImpl* BackendImpl::OpenEntryImpl(const std::string& key) {
+  if (disabled_)
+    return NULL;
+
+  TimeTicks start = TimeTicks::Now();
+  uint32 hash = base::Hash(key);
+  Trace("Open hash 0x%x", hash);
+
+  bool error;
+  EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
+  if (cache_entry && ENTRY_NORMAL != cache_entry->entry()->Data()->state) {
+    // The entry was already evicted.
+    cache_entry->Release();
+    cache_entry = NULL;
+  }
+
+  int current_size = data_->header.num_bytes / (1024 * 1024);
+  int64 total_hours = stats_.GetCounter(Stats::TIMER) / 120;
+  int64 no_use_hours = stats_.GetCounter(Stats::LAST_REPORT_TIMER) / 120;
+  int64 use_hours = total_hours - no_use_hours;
+
+  if (!cache_entry) {
+    CACHE_UMA(AGE_MS, "OpenTime.Miss", 0, start);
+    CACHE_UMA(COUNTS_10000, "AllOpenBySize.Miss", 0, current_size);
+    CACHE_UMA(HOURS, "AllOpenByTotalHours.Miss", 0, total_hours);
+    CACHE_UMA(HOURS, "AllOpenByUseHours.Miss", 0, use_hours);
+    stats_.OnEvent(Stats::OPEN_MISS);
+    return NULL;
+  }
+
+  eviction_.OnOpenEntry(cache_entry);
+  entry_count_++;
+
+  Trace("Open hash 0x%x end: 0x%x", hash,
+        cache_entry->entry()->address().value());
+  CACHE_UMA(AGE_MS, "OpenTime", 0, start);
+  CACHE_UMA(COUNTS_10000, "AllOpenBySize.Hit", 0, current_size);
+  CACHE_UMA(HOURS, "AllOpenByTotalHours.Hit", 0, total_hours);
+  CACHE_UMA(HOURS, "AllOpenByUseHours.Hit", 0, use_hours);
+  stats_.OnEvent(Stats::OPEN_HIT);
+  SIMPLE_STATS_COUNTER("disk_cache.hit");
+  return cache_entry;
 }
 
-int BackendImpl::CreateEntry(const std::string& key, Entry** entry,
-                             const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.CreateEntry(key, entry, callback);
-  return net::ERR_IO_PENDING;
+EntryImpl* BackendImpl::CreateEntryImpl(const std::string& key) {
+  if (disabled_ || key.empty())
+    return NULL;
+
+  TimeTicks start = TimeTicks::Now();
+  Trace("Create hash 0x%x", hash);
+
+  scoped_refptr<EntryImpl> parent;
+  Addr entry_address(data_->table[hash & mask_]);
+  if (entry_address.is_initialized()) {
+    // We have an entry already. It could be the one we are looking for, or just
+    // a hash conflict.
+    bool error;
+    EntryImpl* old_entry = MatchEntry(key, hash, false, Addr(), &error);
+    if (old_entry)
+      return ResurrectEntry(old_entry);
+
+    EntryImpl* parent_entry = MatchEntry(key, hash, true, Addr(), &error);
+    DCHECK(!error);
+    if (parent_entry) {
+      parent.swap(&parent_entry);
+    } else if (data_->table[hash & mask_]) {
+      // We should have corrected the problem.
+      NOTREACHED();
+      return NULL;
+    }
+  }
+
+  // The general flow is to allocate disk space and initialize the entry data,
+  // followed by saving that to disk, then linking the entry though the index
+  // and finally through the lists. If there is a crash in this process, we may
+  // end up with:
+  // a. Used, unreferenced empty blocks on disk (basically just garbage).
+  // b. Used, unreferenced but meaningful data on disk (more garbage).
+  // c. A fully formed entry, reachable only through the index.
+  // d. A fully formed entry, also reachable through the lists, but still dirty.
+  //
+  // Anything after (b) can be automatically cleaned up. We may consider saving
+  // the current operation (as we do while manipulating the lists) so that we
+  // can detect and cleanup (a) and (b).
+
+  int num_blocks = EntryImpl::NumBlocksForEntry(key.size());
+  if (!block_files_.CreateBlock(BLOCK_256, num_blocks, &entry_address)) {
+    LOG(ERROR) << "Create entry failed " << key.c_str();
+    stats_.OnEvent(Stats::CREATE_ERROR);
+    return NULL;
+  }
+
+  Addr node_address(0);
+  if (!block_files_.CreateBlock(RANKINGS, 1, &node_address)) {
+    block_files_.DeleteBlock(entry_address, false);
+    LOG(ERROR) << "Create entry failed " << key.c_str();
+    stats_.OnEvent(Stats::CREATE_ERROR);
+    return NULL;
+  }
+
+  scoped_refptr<EntryImpl> cache_entry(
+      new EntryImpl(this, entry_address, false));
+  IncreaseNumRefs();
+
+  if (!cache_entry->CreateEntry(node_address, key, hash)) {
+    block_files_.DeleteBlock(entry_address, false);
+    block_files_.DeleteBlock(node_address, false);
+    LOG(ERROR) << "Create entry failed " << key.c_str();
+    stats_.OnEvent(Stats::CREATE_ERROR);
+    return NULL;
+  }
+
+  cache_entry->BeginLogging(net_log_, true);
+
+  // We are not failing the operation; let's add this to the map.
+  open_entries_[entry_address.value()] = cache_entry.get();
+
+  // Save the entry.
+  cache_entry->entry()->Store();
+  cache_entry->rankings()->Store();
+  IncreaseNumEntries();
+  entry_count_++;
+
+  // Link this entry through the index.
+  if (parent.get()) {
+    parent->SetNextAddress(entry_address);
+  } else {
+    data_->table[hash & mask_] = entry_address.value();
+  }
+
+  // Link this entry through the lists.
+  eviction_.OnCreateEntry(cache_entry.get());
+
+  CACHE_UMA(AGE_MS, "CreateTime", 0, start);
+  stats_.OnEvent(Stats::CREATE_HIT);
+  SIMPLE_STATS_COUNTER("disk_cache.miss");
+  Trace("create entry hit ");
+  FlushIndex();
+  cache_entry->AddRef();
+  return cache_entry.get();
 }
 
-int BackendImpl::DoomEntry(const std::string& key,
-                           const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.DoomEntry(key, callback);
-  return net::ERR_IO_PENDING;
+int BackendImpl::SyncDoomEntry(const std::string& key) {
+  if (disabled_)
+    return net::ERR_FAILED;
+
+  EntryImpl* entry = OpenEntryImpl(key);
+  if (!entry)
+    return net::ERR_FAILED;
+
+  entry->DoomImpl();
+  entry->Release();
+  return net::OK;
 }
 
-int BackendImpl::DoomAllEntries(const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.DoomAllEntries(callback);
-  return net::ERR_IO_PENDING;
+int BackendImpl::SyncDoomAllEntries() {
+  // This is not really an error, but it is an interesting condition.
+  ReportError(ERR_CACHE_DOOMED);
+  stats_.OnEvent(Stats::DOOM_CACHE);
+  if (!num_refs_) {
+    RestartCache(false);
+    return disabled_ ? net::ERR_FAILED : net::OK;
+  } else {
+    if (disabled_)
+      return net::ERR_FAILED;
+
+    eviction_.TrimCache(true);
+    return net::OK;
+  }
 }
 
-int BackendImpl::DoomEntriesBetween(const base::Time initial_time,
-                                    const base::Time end_time,
-                                    const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.DoomEntriesBetween(initial_time, end_time, callback);
-  return net::ERR_IO_PENDING;
+int BackendImpl::SyncDoomEntriesBetween(const base::Time initial_time,
+                                        const base::Time end_time) {
+  DCHECK_NE(net::APP_CACHE, cache_type_);
+  if (end_time.is_null())
+    return SyncDoomEntriesSince(initial_time);
+
+  DCHECK(end_time >= initial_time);
+
+  if (disabled_)
+    return net::ERR_FAILED;
+
+  EntryImpl* node;
+  void* iter = NULL;
+  EntryImpl* next = OpenNextEntryImpl(&iter);
+  if (!next)
+    return net::OK;
+
+  while (next) {
+    node = next;
+    next = OpenNextEntryImpl(&iter);
+
+    if (node->GetLastUsed() >= initial_time &&
+        node->GetLastUsed() < end_time) {
+      node->DoomImpl();
+    } else if (node->GetLastUsed() < initial_time) {
+      if (next)
+        next->Release();
+      next = NULL;
+      SyncEndEnumeration(iter);
+    }
+
+    node->Release();
+  }
+
+  return net::OK;
 }
 
-int BackendImpl::DoomEntriesSince(const base::Time initial_time,
-                                  const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.DoomEntriesSince(initial_time, callback);
-  return net::ERR_IO_PENDING;
+// We use OpenNextEntryImpl to retrieve elements from the cache, until we get
+// entries that are too old.
+int BackendImpl::SyncDoomEntriesSince(const base::Time initial_time) {
+  DCHECK_NE(net::APP_CACHE, cache_type_);
+  if (disabled_)
+    return net::ERR_FAILED;
+
+  stats_.OnEvent(Stats::DOOM_RECENT);
+  for (;;) {
+    void* iter = NULL;
+    EntryImpl* entry = OpenNextEntryImpl(&iter);
+    if (!entry)
+      return net::OK;
+
+    if (initial_time > entry->GetLastUsed()) {
+      entry->Release();
+      SyncEndEnumeration(iter);
+      return net::OK;
+    }
+
+    entry->DoomImpl();
+    entry->Release();
+    SyncEndEnumeration(iter);  // Dooming the entry invalidates the iterator.
+  }
 }
 
 int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
@@ -1254,73 +781,23 @@
   stats_.GetItems(stats);
 }
 
-void BackendImpl::OnExternalCacheHit(const std::string& key) {
-  background_queue_.OnExternalCacheHit(key);
-}
+void BackendImpl::SyncOnExternalCacheHit(const std::string& key) {
+  if (disabled_)
+    return;
 
-// ------------------------------------------------------------------------
-
-// We just created a new file so we're going to write the header and set the
-// file length to include the hash table (zero filled).
-bool BackendImpl::CreateBackingStore(disk_cache::File* file) {
-  AdjustMaxCacheSize(0);
-
-  IndexHeader header;
-  header.table_len = DesiredIndexTableLen(max_size_);
-
-  // We need file version 2.1 for the new eviction algorithm.
-  if (new_eviction_)
-    header.version = 0x20001;
-
-  header.create_time = Time::Now().ToInternalValue();
-
-  if (!file->Write(&header, sizeof(header), 0))
-    return false;
-
-  return file->SetLength(GetIndexSize(header.table_len));
-}
-
-bool BackendImpl::InitBackingStore(bool* file_created) {
-  if (!file_util::CreateDirectory(path_))
-    return false;
-
-  base::FilePath index_name = path_.AppendASCII(kIndexName);
-
-  int flags = base::PLATFORM_FILE_READ |
-              base::PLATFORM_FILE_WRITE |
-              base::PLATFORM_FILE_OPEN_ALWAYS |
-              base::PLATFORM_FILE_EXCLUSIVE_WRITE;
-  scoped_refptr<disk_cache::File> file(new disk_cache::File(
-      base::CreatePlatformFile(index_name, flags, file_created, NULL)));
-
-  if (!file->IsValid())
-    return false;
-
-  bool ret = true;
-  if (*file_created)
-    ret = CreateBackingStore(file.get());
-
-  file = NULL;
-  if (!ret)
-    return false;
-
-  index_ = new MappedFile();
-  data_ = reinterpret_cast<Index*>(index_->Init(index_name, 0));
-  if (!data_) {
-    LOG(ERROR) << "Unable to map Index file";
-    return false;
+  uint32 hash = base::Hash(key);
+  bool error;
+  EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
+  if (cache_entry) {
+    if (ENTRY_NORMAL == cache_entry->entry()->Data()->state) {
+      UpdateRank(cache_entry, cache_type() == net::SHADER_CACHE);
+    }
+    cache_entry->Release();
   }
-
-  if (index_->GetLength() < sizeof(Index)) {
-    // We verify this again on CheckIndex() but it's easier to make sure now
-    // that the header is there.
-    LOG(ERROR) << "Corrupt Index file";
-    return false;
-  }
-
-  return true;
 }
 
+// ------------------------------------------------------------------------
+
 // The maximum cache size will be either set explicitly by the caller, or
 // calculated by this code.
 void BackendImpl::AdjustMaxCacheSize(int table_len) {
@@ -1458,6 +935,31 @@
   restarted_ = true;
 }
 
+void BackendImpl::CleanupCache() {
+  Trace("Backend Cleanup");
+  eviction_.Stop();
+  timer_.reset();
+
+  if (init_) {
+    StoreStats();
+    if (data_)
+      data_->header.crash = 0;
+
+    if (user_flags_ & kNoRandom) {
+      // This is a net_unittest, verify that we are not 'leaking' entries.
+      File::WaitForPendingIO(&num_pending_io_);
+      DCHECK(!num_refs_);
+    } else {
+      File::DropPendingIO();
+    }
+  }
+  block_files_.CloseFiles();
+  FlushIndex();
+  index_ = NULL;
+  ptr_factory_.InvalidateWeakPtrs();
+  done_.Signal();
+}
+
 int BackendImpl::NewEntry(Addr address, EntryImpl** entry) {
   EntriesMap::iterator it = open_entries_.find(address.value());
   if (it != open_entries_.end()) {
@@ -1535,108 +1037,6 @@
   return 0;
 }
 
-EntryImpl* BackendImpl::MatchEntry(const std::string& key, uint32 hash,
-                                   bool find_parent, Addr entry_addr,
-                                   bool* match_error) {
-  Addr address(data_->table[hash & mask_]);
-  scoped_refptr<EntryImpl> cache_entry, parent_entry;
-  EntryImpl* tmp = NULL;
-  bool found = false;
-  std::set<CacheAddr> visited;
-  *match_error = false;
-
-  for (;;) {
-    if (disabled_)
-      break;
-
-    if (visited.find(address.value()) != visited.end()) {
-      // It's possible for a buggy version of the code to write a loop. Just
-      // break it.
-      Trace("Hash collision loop 0x%x", address.value());
-      address.set_value(0);
-      parent_entry->SetNextAddress(address);
-    }
-    visited.insert(address.value());
-
-    if (!address.is_initialized()) {
-      if (find_parent)
-        found = true;
-      break;
-    }
-
-    int error = NewEntry(address, &tmp);
-    cache_entry.swap(&tmp);
-
-    if (error || cache_entry->dirty()) {
-      // This entry is dirty on disk (it was not properly closed): we cannot
-      // trust it.
-      Addr child(0);
-      if (!error)
-        child.set_value(cache_entry->GetNextAddress());
-
-      if (parent_entry.get()) {
-        parent_entry->SetNextAddress(child);
-        parent_entry = NULL;
-      } else {
-        data_->table[hash & mask_] = child.value();
-      }
-
-      Trace("MatchEntry dirty %d 0x%x 0x%x", find_parent, entry_addr.value(),
-            address.value());
-
-      if (!error) {
-        // It is important to call DestroyInvalidEntry after removing this
-        // entry from the table.
-        DestroyInvalidEntry(cache_entry.get());
-        cache_entry = NULL;
-      } else {
-        Trace("NewEntry failed on MatchEntry 0x%x", address.value());
-      }
-
-      // Restart the search.
-      address.set_value(data_->table[hash & mask_]);
-      visited.clear();
-      continue;
-    }
-
-    DCHECK_EQ(hash & mask_, cache_entry->entry()->Data()->hash & mask_);
-    if (cache_entry->IsSameEntry(key, hash)) {
-      if (!cache_entry->Update())
-        cache_entry = NULL;
-      found = true;
-      if (find_parent && entry_addr.value() != address.value()) {
-        Trace("Entry not on the index 0x%x", address.value());
-        *match_error = true;
-        parent_entry = NULL;
-      }
-      break;
-    }
-    if (!cache_entry->Update())
-      cache_entry = NULL;
-    parent_entry = cache_entry;
-    cache_entry = NULL;
-    if (!parent_entry.get())
-      break;
-
-    address.set_value(parent_entry->GetNextAddress());
-  }
-
-  if (parent_entry.get() && (!find_parent || !found))
-    parent_entry = NULL;
-
-  if (find_parent && entry_addr.is_initialized() && !cache_entry.get()) {
-    *match_error = true;
-    parent_entry = NULL;
-  }
-
-  if (cache_entry.get() && (find_parent || !found))
-    cache_entry = NULL;
-
-  find_parent ? parent_entry.swap(&tmp) : cache_entry.swap(&tmp);
-  FlushIndex();
-  return tmp;
-}
-
 // This is the actual implementation for OpenNextEntry and OpenPrevEntry.
 EntryImpl* BackendImpl::OpenFollowingEntry(bool forward, void** iter) {
   if (disabled_)
@@ -1715,72 +1115,147 @@
   return next_entry;
 }
 
-bool BackendImpl::OpenFollowingEntryFromList(bool forward, Rankings::List list,
-                                             CacheRankingsBlock** from_entry,
-                                             EntryImpl** next_entry) {
-  if (disabled_)
-    return false;
+void BackendImpl::AddStorageSize(int32 bytes) {
+  data_->header.num_bytes += bytes;
+  DCHECK_GE(data_->header.num_bytes, 0);
+}
 
-  if (!new_eviction_ && Rankings::NO_USE != list)
-    return false;
+void BackendImpl::SubstractStorageSize(int32 bytes) {
+  data_->header.num_bytes -= bytes;
+  DCHECK_GE(data_->header.num_bytes, 0);
+}
 
-  Rankings::ScopedRankingsBlock rankings(&rankings_, *from_entry);
-  CacheRankingsBlock* next_block = forward ?
-      rankings_.GetNext(rankings.get(), list) :
-      rankings_.GetPrev(rankings.get(), list);
-  Rankings::ScopedRankingsBlock next(&rankings_, next_block);
-  *from_entry = NULL;
+void BackendImpl::IncreaseNumRefs() {
+  num_refs_++;
+  if (max_refs_ < num_refs_)
+    max_refs_ = num_refs_;
+}
 
-  *next_entry = GetEnumeratedEntry(next.get(), list);
-  if (!*next_entry)
-    return false;
+void BackendImpl::DecreaseNumRefs() {
+  DCHECK(num_refs_);
+  num_refs_--;
 
-  *from_entry = next.release();
-  return true;
+  if (!num_refs_ && disabled_)
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
 }
 
-EntryImpl* BackendImpl::GetEnumeratedEntry(CacheRankingsBlock* next,
-                                           Rankings::List list) {
-  if (!next || disabled_)
-    return NULL;
+void BackendImpl::IncreaseNumEntries() {
+  data_->header.num_entries++;
+  DCHECK_GT(data_->header.num_entries, 0);
+}
 
-  EntryImpl* entry;
-  int rv = NewEntry(Addr(next->Data()->contents), &entry);
-  if (rv) {
-    STRESS_NOTREACHED();
-    rankings_.Remove(next, list, false);
-    if (rv == ERR_INVALID_ADDRESS) {
-      // There is nothing linked from the index. Delete the rankings node.
-      DeleteBlock(next->address(), true);
-    }
-    return NULL;
+void BackendImpl::DecreaseNumEntries() {
+  data_->header.num_entries--;
+  if (data_->header.num_entries < 0) {
+    NOTREACHED();
+    data_->header.num_entries = 0;
   }
+}
 
-  if (entry->dirty()) {
-    // We cannot trust this entry.
-    InternalDoomEntry(entry);
-    entry->Release();
-    return NULL;
+int BackendImpl::SyncInit() {
+#if defined(NET_BUILD_STRESS_CACHE)
+  // Start evictions right away.
+  up_ticks_ = kTrimDelay * 2;
+#endif
+  DCHECK(!init_);
+  if (init_)
+    return net::ERR_FAILED;
+
+  bool create_files = false;
+  if (!InitBackingStore(&create_files)) {
+    ReportError(ERR_STORAGE_ERROR);
+    return net::ERR_FAILED;
   }
 
-  if (!entry->Update()) {
-    STRESS_NOTREACHED();
-    entry->Release();
-    return NULL;
+  num_refs_ = num_pending_io_ = max_refs_ = 0;
+  entry_count_ = byte_count_ = 0;
+
+  if (!restarted_) {
+    buffer_bytes_ = 0;
+    trace_object_ = TraceObject::GetTraceObject();
+    // Create a recurrent timer of 30 secs.
+    int timer_delay = unit_test_ ? 1000 : 30000;
+    timer_.reset(new base::RepeatingTimer<BackendImpl>());
+    timer_->Start(FROM_HERE, TimeDelta::FromMilliseconds(timer_delay), this,
+                  &BackendImpl::OnStatsTimer);
   }
 
-  // Note that it is unfortunate (but possible) for this entry to be clean, but
-  // not actually the real entry. In other words, we could have lost this entry
-  // from the index, and it could have been replaced with a newer one. It's not
-  // worth checking that this entry is "the real one", so we just return it and
-  // let the enumeration continue; this entry will be evicted at some point, and
-  // the regular path will work with the real entry. With time, this problem
-  // will disasappear because this scenario is just a bug.
+  init_ = true;
+  Trace("Init");
 
-  // Make sure that we save the key for later.
-  entry->GetKey();
+  if (data_->header.experiment != NO_EXPERIMENT &&
+      cache_type_ != net::DISK_CACHE) {
+    // No experiment for other caches.
+    return net::ERR_FAILED;
+  }
 
-  return entry;
+  if (!(user_flags_ & kNoRandom)) {
+    // The unit test controls directly what to test.
+    new_eviction_ = (cache_type_ == net::DISK_CACHE);
+  }
+
+  if (!CheckIndex()) {
+    ReportError(ERR_INIT_FAILED);
+    return net::ERR_FAILED;
+  }
+
+  if (!restarted_ && (create_files || !data_->header.num_entries))
+    ReportError(ERR_CACHE_CREATED);
+
+  if (!(user_flags_ & kNoRandom) && cache_type_ == net::DISK_CACHE &&
+      !InitExperiment(&data_->header, create_files)) {
+    return net::ERR_FAILED;
+  }
+
+  // We don't care if the value overflows. The only thing we care about is that
+  // the id cannot be zero, because that value is used as "not dirty".
+  // Increasing the value once per second gives us many years before we start
+  // having collisions.
+  data_->header.this_id++;
+  if (!data_->header.this_id)
+    data_->header.this_id++;
+
+  bool previous_crash = (data_->header.crash != 0);
+  data_->header.crash = 1;
+
+  if (!block_files_.Init(create_files))
+    return net::ERR_FAILED;
+
+  // We want to minimize the changes to cache for an AppCache.
+  if (cache_type() == net::APP_CACHE) {
+    DCHECK(!new_eviction_);
+    read_only_ = true;
+  } else if (cache_type() == net::SHADER_CACHE) {
+    DCHECK(!new_eviction_);
+  }
+
+  eviction_.Init(this);
+
+  // stats_ and rankings_ may end up calling back to us so we better be enabled.
+  disabled_ = false;
+  if (!InitStats())
+    return net::ERR_FAILED;
+
+  disabled_ = !rankings_.Init(this, new_eviction_);
+
+#if defined(STRESS_CACHE_EXTENDED_VALIDATION)
+  trace_object_->EnableTracing(false);
+  int sc = SelfCheck();
+  if (sc < 0 && sc != ERR_NUM_ENTRIES_MISMATCH)
+    NOTREACHED();
+  trace_object_->EnableTracing(true);
+#endif
+
+  if (previous_crash) {
+    ReportError(ERR_PREVIOUS_CRASH);
+  } else if (!restarted_) {
+    ReportError(ERR_NO_ERROR);
+  }
+
+  FlushIndex();
+
+  return disabled_ ? net::ERR_FAILED : net::OK;
 }
 
 EntryImpl* BackendImpl::ResurrectEntry(EntryImpl* deleted_entry) {
@@ -1802,56 +1277,102 @@
   return deleted_entry;
 }
 
-void BackendImpl::DestroyInvalidEntry(EntryImpl* entry) {
-  LOG(WARNING) << "Destroying invalid entry.";
-  Trace("Destroying invalid entry 0x%p", entry);
+EntryImpl* BackendImpl::CreateEntryImpl(const std::string& key) {
+  if (disabled_ || key.empty())
+    return NULL;
 
-  entry->SetPointerForInvalidEntry(GetCurrentEntryId());
+  TimeTicks start = TimeTicks::Now();
+  Trace("Create hash 0x%x", hash);
 
-  eviction_.OnDoomEntry(entry);
-  entry->InternalDoom();
+  scoped_refptr<EntryImpl> parent;
+  Addr entry_address(data_->table[hash & mask_]);
+  if (entry_address.is_initialized()) {
+    // We have an entry already. It could be the one we are looking for, or just
+    // a hash conflict.
+    bool error;
+    EntryImpl* old_entry = MatchEntry(key, hash, false, Addr(), &error);
+    if (old_entry)
+      return ResurrectEntry(old_entry);
 
-  if (!new_eviction_)
-    DecreaseNumEntries();
-  stats_.OnEvent(Stats::INVALID_ENTRY);
-}
+    EntryImpl* parent_entry = MatchEntry(key, hash, true, Addr(), &error);
+    DCHECK(!error);
+    if (parent_entry) {
+      parent.swap(&parent_entry);
+    } else if (data_->table[hash & mask_]) {
+      // We should have corrected the problem.
+      NOTREACHED();
+      return NULL;
+    }
+  }
 
-void BackendImpl::AddStorageSize(int32 bytes) {
-  data_->header.num_bytes += bytes;
-  DCHECK_GE(data_->header.num_bytes, 0);
-}
+  // The general flow is to allocate disk space and initialize the entry data,
+  // followed by saving that to disk, then linking the entry though the index
+  // and finally through the lists. If there is a crash in this process, we may
+  // end up with:
+  // a. Used, unreferenced empty blocks on disk (basically just garbage).
+  // b. Used, unreferenced but meaningful data on disk (more garbage).
+  // c. A fully formed entry, reachable only through the index.
+  // d. A fully formed entry, also reachable through the lists, but still dirty.
+  //
+  // Anything after (b) can be automatically cleaned up. We may consider saving
+  // the current operation (as we do while manipulating the lists) so that we
+  // can detect and cleanup (a) and (b).
 
-void BackendImpl::SubstractStorageSize(int32 bytes) {
-  data_->header.num_bytes -= bytes;
-  DCHECK_GE(data_->header.num_bytes, 0);
-}
+  int num_blocks = EntryImpl::NumBlocksForEntry(key.size());
+  if (!block_files_.CreateBlock(BLOCK_256, num_blocks, &entry_address)) {
+    LOG(ERROR) << "Create entry failed " << key.c_str();
+    stats_.OnEvent(Stats::CREATE_ERROR);
+    return NULL;
+  }
 
-void BackendImpl::IncreaseNumRefs() {
-  num_refs_++;
-  if (max_refs_ < num_refs_)
-    max_refs_ = num_refs_;
-}
+  Addr node_address(0);
+  if (!block_files_.CreateBlock(RANKINGS, 1, &node_address)) {
+    block_files_.DeleteBlock(entry_address, false);
+    LOG(ERROR) << "Create entry failed " << key.c_str();
+    stats_.OnEvent(Stats::CREATE_ERROR);
+    return NULL;
+  }
 
-void BackendImpl::DecreaseNumRefs() {
-  DCHECK(num_refs_);
-  num_refs_--;
+  scoped_refptr<EntryImpl> cache_entry(
+      new EntryImpl(this, entry_address, false));
+  IncreaseNumRefs();
 
-  if (!num_refs_ && disabled_)
-    base::MessageLoop::current()->PostTask(
-        FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
-}
+  if (!cache_entry->CreateEntry(node_address, key, hash)) {
+    block_files_.DeleteBlock(entry_address, false);
+    block_files_.DeleteBlock(node_address, false);
+    LOG(ERROR) << "Create entry failed " << key.c_str();
+    stats_.OnEvent(Stats::CREATE_ERROR);
+    return NULL;
+  }
 
-void BackendImpl::IncreaseNumEntries() {
-  data_->header.num_entries++;
-  DCHECK_GT(data_->header.num_entries, 0);
-}
+  cache_entry->BeginLogging(net_log_, true);
 
-void BackendImpl::DecreaseNumEntries() {
-  data_->header.num_entries--;
-  if (data_->header.num_entries < 0) {
-    NOTREACHED();
-    data_->header.num_entries = 0;
+  // We are not failing the operation; let's add this to the map.
+  open_entries_[entry_address.value()] = cache_entry;
+
+  // Save the entry.
+  cache_entry->entry()->Store();
+  cache_entry->rankings()->Store();
+  IncreaseNumEntries();
+  entry_count_++;
+
+  // Link this entry through the index.
+  if (parent.get()) {
+    parent->SetNextAddress(entry_address);
+  } else {
+    data_->table[hash & mask_] = entry_address.value();
   }
+
+  // Link this entry through the lists.
+  eviction_.OnCreateEntry(cache_entry);
+
+  CACHE_UMA(AGE_MS, "CreateTime", 0, start);
+  stats_.OnEvent(Stats::CREATE_HIT);
+  SIMPLE_STATS_COUNTER("disk_cache.miss");
+  Trace("create entry hit ");
+  FlushIndex();
+  cache_entry->AddRef();
+  return cache_entry.get();
 }
 
 void BackendImpl::LogStats() {
@@ -1968,12 +1489,13 @@
     block_files_.ReportStats();
 }
 
-void BackendImpl::UpgradeTo2_1() {
-  // 2.1 is basically the same as 2.0, except that new fields are actually
-  // updated by the new eviction algorithm.
-  DCHECK(0x20000 == data_->header.version);
-  data_->header.version = 0x20001;
-  data_->header.lru.sizes[Rankings::NO_USE] = data_->header.num_entries;
+void BackendImpl::ReportError(int error) {
+  STRESS_DCHECK(!error || error == ERR_PREVIOUS_CRASH ||
+                error == ERR_CACHE_CREATED);
+
+  // We transmit positive numbers, instead of direct error codes.
+  DCHECK_LE(error, 0);
+  CACHE_UMA(CACHE_ERROR, "Error", 0, error * -1);
 }
 
 bool BackendImpl::CheckIndex() {