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

net/disk_cache/v3/backend_worker.cc

Index: net/disk_cache/v3/backend_worker.cc
===================================================================
--- net/disk_cache/v3/backend_worker.cc	(revision 0)
+++ net/disk_cache/v3/backend_worker.cc	(working copy)
@@ -97,48 +97,12 @@
   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)
@@ -164,60 +128,6 @@
       ptr_factory_(this) {
 }
 
-BackendImpl::BackendImpl(const base::FilePath& path,
-                         uint32 mask,
-                         base::MessageLoopProxy* cache_thread,
-                         net::NetLog* net_log)
-    : background_queue_(this, cache_thread),
-      path_(path),
-      block_files_(path),
-      mask_(mask),
-      max_size_(0),
-      up_ticks_(0),
-      cache_type_(net::DISK_CACHE),
-      uma_report_(0),
-      user_flags_(kMask),
-      init_(false),
-      restarted_(false),
-      unit_test_(false),
-      read_only_(false),
-      disabled_(false),
-      new_eviction_(false),
-      first_timer_(true),
-      user_load_(false),
-      net_log_(net_log),
-      done_(true, false),
-      ptr_factory_(this) {
-}
-
-BackendImpl::~BackendImpl() {
-  if (user_flags_ & kNoRandom) {
-    // This is a unit test, so we want to be strict about not leaking entries
-    // and completing all the work.
-    background_queue_.WaitForPendingIO();
-  } else {
-    // This is most likely not a test, so we want to do as little work as
-    // possible at this time, at the price of leaving dirty entries behind.
-    background_queue_.DropPendingIO();
-  }
-
-  if (background_queue_.BackgroundIsCurrentThread()) {
-    // Unit tests may use the same thread for everything.
-    CleanupCache();
-  } else {
-    background_queue_.background_thread()->PostTask(
-        FROM_HERE, base::Bind(&FinalCleanupCallback, base::Unretained(this)));
-    // http://crbug.com/74623
-    base::ThreadRestrictions::ScopedAllowWait allow_wait;
-    done_.Wait();
-  }
-}
-
-int BackendImpl::Init(const CompletionCallback& callback) {
-  background_queue_.Init(callback);
-  return net::ERR_IO_PENDING;
-}
-
 int BackendImpl::SyncInit() {
 #if defined(NET_BUILD_STRESS_CACHE)
   // Start evictions right away.
@@ -323,6 +233,48 @@
   return disabled_ ? net::ERR_FAILED : net::OK;
 }
 
+void BackendImpl::PrepareForRestart() {
+  // Reset the mask_ if it was not given by the user.
+  if (!(user_flags_ & kMask))
+    mask_ = 0;
+
+  if (!(user_flags_ & kNewEviction))
+    new_eviction_ = false;
+
+  disabled_ = true;
+  data_->header.crash = 0;
+  index_->Flush();
+  index_ = NULL;
+  data_ = NULL;
+  block_files_.CloseFiles();
+  rankings_.Reset();
+  init_ = false;
+  restarted_ = true;
+}
+
+BackendImpl::~BackendImpl() {
+  if (user_flags_ & kNoRandom) {
+    // This is a unit test, so we want to be strict about not leaking entries
+    // and completing all the work.
+    background_queue_.WaitForPendingIO();
+  } else {
+    // This is most likely not a test, so we want to do as little work as
+    // possible at this time, at the price of leaving dirty entries behind.
+    background_queue_.DropPendingIO();
+  }
+
+  if (background_queue_.BackgroundIsCurrentThread()) {
+    // Unit tests may use the same thread for everything.
+    CleanupCache();
+  } else {
+    background_queue_.background_thread()->PostTask(
+        FROM_HERE, base::Bind(&FinalCleanupCallback, base::Unretained(this)));
+    // http://crbug.com/74623
+    base::ThreadRestrictions::ScopedAllowWait allow_wait;
+    done_.Wait();
+  }
+}
+
 void BackendImpl::CleanupCache() {
   Trace("Backend Cleanup");
   eviction_.Stop();
@@ -348,323 +300,6 @@
   done_.Signal();
 }
 
-// ------------------------------------------------------------------------
-
-int BackendImpl::OpenPrevEntry(void** iter, Entry** prev_entry,
-                               const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.OpenPrevEntry(iter, prev_entry, callback);
-  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)
-    return false;
-
-  // Zero size means use the default.
-  if (!max_bytes)
-    return true;
-
-  // Avoid a DCHECK later on.
-  if (max_bytes >= kint32max - kint32max / 10)
-    max_bytes = kint32max - kint32max / 10 - 1;
-
-  user_flags_ |= kMaxSize;
-  max_size_ = max_bytes;
-  return true;
-}
-
-void BackendImpl::SetType(net::CacheType type) {
-  DCHECK_NE(net::MEMORY_CACHE, type);
-  cache_type_ = type;
-}
-
 base::FilePath BackendImpl::GetFileName(Addr address) const {
   if (!address.is_separate_file() || !address.is_initialized()) {
     NOTREACHED();
@@ -675,591 +310,6 @@
   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();
-  Addr entry_addr = entry->entry()->address();
-  bool error;
-  EntryImpl* parent_entry = MatchEntry(key, hash, true, entry_addr, &error);
-  CacheAddr child(entry->GetNextAddress());
-
-  Trace("Doom entry 0x%p", entry);
-
-  if (!entry->doomed()) {
-    // We may have doomed this entry from within MatchEntry.
-    eviction_.OnDoomEntry(entry);
-    entry->InternalDoom();
-    if (!new_eviction_) {
-      DecreaseNumEntries();
-    }
-    stats_.OnEvent(Stats::DOOM_ENTRY);
-  }
-
-  if (parent_entry) {
-    parent_entry->SetNextAddress(Addr(child));
-    parent_entry->Release();
-  } else if (!error) {
-    data_->table[hash & mask_] = child;
-  }
-
-  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())
-    open_entries_.erase(it);
-}
-
-void BackendImpl::OnEntryDestroyEnd() {
-  DecreaseNumRefs();
-  if (data_->header.num_bytes > max_size_ && !read_only_ &&
-      (up_ticks_ > kTrimDelay || user_flags_ & kNoRandom))
-    eviction_.TrimCache(false);
-}
-
-EntryImpl* BackendImpl::GetOpenEntry(CacheRankingsBlock* rankings) const {
-  DCHECK(rankings->HasData());
-  EntriesMap::const_iterator it =
-      open_entries_.find(rankings->Data()->contents);
-  if (it != open_entries_.end()) {
-    // We have this entry in memory.
-    return it->second;
-  }
-
-  return NULL;
-}
-
-int32 BackendImpl::GetCurrentEntryId() const {
-  return data_->header.this_id;
-}
-
-int BackendImpl::MaxFileSize() const {
-  return max_size_ / 8;
-}
-
-void BackendImpl::ModifyStorageSize(int32 old_size, int32 new_size) {
-  if (disabled_ || old_size == new_size)
-    return;
-  if (old_size > new_size)
-    SubstractStorageSize(old_size - new_size);
-  else
-    AddStorageSize(new_size - old_size);
-
-  FlushIndex();
-
-  // Update the usage statistics.
-  stats_.ModifyStorageStats(old_size, new_size);
-}
-
-void BackendImpl::TooMuchStorageRequested(int32 size) {
-  stats_.ModifyStorageStats(0, size);
-}
-
-bool BackendImpl::IsAllocAllowed(int current_size, int new_size) {
-  DCHECK_GT(new_size, current_size);
-  if (user_flags_ & kNoBuffering)
-    return false;
-
-  int to_add = new_size - current_size;
-  if (buffer_bytes_ + to_add > MaxBuffersSize())
-    return false;
-
-  buffer_bytes_ += to_add;
-  CACHE_UMA(COUNTS_50000, "BufferBytes", 0, buffer_bytes_ / 1024);
-  return true;
-}
-
-void BackendImpl::BufferDeleted(int size) {
-  buffer_bytes_ -= size;
-  DCHECK_GE(size, 0);
-}
-
-bool BackendImpl::IsLoaded() const {
-  CACHE_UMA(COUNTS, "PendingIO", 0, num_pending_io_);
-  if (user_flags_ & kNoLoadProtection)
-    return false;
-
-  return (num_pending_io_ > 5 || user_load_);
-}
-
-std::string BackendImpl::HistogramName(const char* name, int experiment) const {
-  if (!experiment)
-    return base::StringPrintf("DiskCache.%d.%s", cache_type_, name);
-  return base::StringPrintf("DiskCache.%d.%s_%d", cache_type_,
-                            name, experiment);
-}
-
-base::WeakPtr<BackendImpl> BackendImpl::GetWeakPtr() {
-  return ptr_factory_.GetWeakPtr();
-}
-
-// We want to remove biases from some histograms so we only send data once per
-// week.
-bool BackendImpl::ShouldReportAgain() {
-  if (uma_report_)
-    return uma_report_ == 2;
-
-  uma_report_++;
-  int64 last_report = stats_.GetCounter(Stats::LAST_REPORT);
-  Time last_time = Time::FromInternalValue(last_report);
-  if (!last_report || (Time::Now() - last_time).InDays() >= 7) {
-    stats_.SetCounter(Stats::LAST_REPORT, Time::Now().ToInternalValue());
-    uma_report_++;
-    return true;
-  }
-  return false;
-}
-
-void BackendImpl::FirstEviction() {
-  DCHECK(data_->header.create_time);
-  if (!GetEntryCount())
-    return;  // This is just for unit tests.
-
-  Time create_time = Time::FromInternalValue(data_->header.create_time);
-  CACHE_UMA(AGE, "FillupAge", 0, create_time);
-
-  int64 use_time = stats_.GetCounter(Stats::TIMER);
-  CACHE_UMA(HOURS, "FillupTime", 0, static_cast<int>(use_time / 120));
-  CACHE_UMA(PERCENTAGE, "FirstHitRatio", 0, stats_.GetHitRatio());
-
-  if (!use_time)
-    use_time = 1;
-  CACHE_UMA(COUNTS_10000, "FirstEntryAccessRate", 0,
-            static_cast<int>(data_->header.num_entries / use_time));
-  CACHE_UMA(COUNTS, "FirstByteIORate", 0,
-            static_cast<int>((data_->header.num_bytes / 1024) / use_time));
-
-  int avg_size = data_->header.num_bytes / GetEntryCount();
-  CACHE_UMA(COUNTS, "FirstEntrySize", 0, avg_size);
-
-  int large_entries_bytes = stats_.GetLargeEntriesSize();
-  int large_ratio = large_entries_bytes * 100 / data_->header.num_bytes;
-  CACHE_UMA(PERCENTAGE, "FirstLargeEntriesRatio", 0, large_ratio);
-
-  if (new_eviction_) {
-    CACHE_UMA(PERCENTAGE, "FirstResurrectRatio", 0, stats_.GetResurrectRatio());
-    CACHE_UMA(PERCENTAGE, "FirstNoUseRatio", 0,
-              data_->header.lru.sizes[0] * 100 / data_->header.num_entries);
-    CACHE_UMA(PERCENTAGE, "FirstLowUseRatio", 0,
-              data_->header.lru.sizes[1] * 100 / data_->header.num_entries);
-    CACHE_UMA(PERCENTAGE, "FirstHighUseRatio", 0,
-              data_->header.lru.sizes[2] * 100 / data_->header.num_entries);
-  }
-
-  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);
-}
-
-void BackendImpl::OnRead(int32 bytes) {
-  DCHECK_GE(bytes, 0);
-  byte_count_ += bytes;
-  if (byte_count_ < 0)
-    byte_count_ = kint32max;
-}
-
-void BackendImpl::OnWrite(int32 bytes) {
-  // We use the same implementation as OnRead... just log the number of bytes.
-  OnRead(bytes);
-}
-
-void BackendImpl::OnStatsTimer() {
-  stats_.OnEvent(Stats::TIMER);
-  int64 time = stats_.GetCounter(Stats::TIMER);
-  int64 current = stats_.GetCounter(Stats::OPEN_ENTRIES);
-
-  // OPEN_ENTRIES is a sampled average of the number of open entries, avoiding
-  // the bias towards 0.
-  if (num_refs_ && (current != num_refs_)) {
-    int64 diff = (num_refs_ - current) / 50;
-    if (!diff)
-      diff = num_refs_ > current ? 1 : -1;
-    current = current + diff;
-    stats_.SetCounter(Stats::OPEN_ENTRIES, current);
-    stats_.SetCounter(Stats::MAX_ENTRIES, max_refs_);
-  }
-
-  CACHE_UMA(COUNTS, "NumberOfReferences", 0, num_refs_);
-
-  CACHE_UMA(COUNTS_10000, "EntryAccessRate", 0, entry_count_);
-  CACHE_UMA(COUNTS, "ByteIORate", 0, byte_count_ / 1024);
-
-  // These values cover about 99.5% of the population (Oct 2011).
-  user_load_ = (entry_count_ > 300 || byte_count_ > 7 * 1024 * 1024);
-  entry_count_ = 0;
-  byte_count_ = 0;
-  up_ticks_++;
-
-  if (!data_)
-    first_timer_ = false;
-  if (first_timer_) {
-    first_timer_ = false;
-    if (ShouldReportAgain())
-      ReportStats();
-  }
-
-  // Save stats to disk at 5 min intervals.
-  if (time % 10 == 0)
-    StoreStats();
-}
-
-void BackendImpl::IncrementIoCount() {
-  num_pending_io_++;
-}
-
-void BackendImpl::DecrementIoCount() {
-  num_pending_io_--;
-}
-
-void BackendImpl::SetUnitTestMode() {
-  user_flags_ |= kUnitTestMode;
-  unit_test_ = true;
-}
-
-void BackendImpl::SetUpgradeMode() {
-  user_flags_ |= kUpgradeMode;
-  read_only_ = true;
-}
-
-void BackendImpl::SetNewEviction() {
-  user_flags_ |= kNewEviction;
-  new_eviction_ = true;
-}
-
-void BackendImpl::SetFlags(uint32 flags) {
-  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);
-}
-
-void BackendImpl::TrimDeletedListForTest(bool empty) {
-  eviction_.SetTestMode();
-  eviction_.TrimDeletedList(empty);
-}
-
-int BackendImpl::SelfCheck() {
-  if (!init_) {
-    LOG(ERROR) << "Init failed";
-    return ERR_INIT_FAILED;
-  }
-
-  int num_entries = rankings_.SelfCheck();
-  if (num_entries < 0) {
-    LOG(ERROR) << "Invalid rankings list, error " << num_entries;
-#if !defined(NET_BUILD_STRESS_CACHE)
-    return num_entries;
-#endif
-  }
-
-  if (num_entries != data_->header.num_entries) {
-    LOG(ERROR) << "Number of entries mismatch";
-#if !defined(NET_BUILD_STRESS_CACHE)
-    return ERR_NUM_ENTRIES_MISMATCH;
-#endif
-  }
-
-  return CheckAllEntries();
-}
-
-void BackendImpl::FlushIndex() {
-  if (index_.get() && !disabled_)
-    index_->Flush();
-}
-
-// ------------------------------------------------------------------------
-
-net::CacheType BackendImpl::GetCacheType() const {
-  return cache_type_;
-}
-
-int32 BackendImpl::GetEntryCount() const {
-  if (!index_.get() || disabled_)
-    return 0;
-  // num_entries includes entries already evicted.
-  int32 not_deleted = data_->header.num_entries -
-                      data_->header.lru.sizes[Rankings::DELETED];
-
-  if (not_deleted < 0) {
-    NOTREACHED();
-    not_deleted = 0;
-  }
-
-  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;
-}
-
-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;
-}
-
-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::DoomAllEntries(const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.DoomAllEntries(callback);
-  return net::ERR_IO_PENDING;
-}
-
-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::DoomEntriesSince(const base::Time initial_time,
-                                  const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.DoomEntriesSince(initial_time, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int BackendImpl::OpenNextEntry(void** iter, Entry** next_entry,
-                               const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-  background_queue_.OpenNextEntry(iter, next_entry, callback);
-  return net::ERR_IO_PENDING;
-}
-
-void BackendImpl::EndEnumeration(void** iter) {
-  background_queue_.EndEnumeration(*iter);
-  *iter = NULL;
-}
-
-void BackendImpl::GetStats(StatsItems* stats) {
-  if (disabled_)
-    return;
-
-  std::pair<std::string, std::string> item;
-
-  item.first = "Entries";
-  item.second = base::StringPrintf("%d", data_->header.num_entries);
-  stats->push_back(item);
-
-  item.first = "Pending IO";
-  item.second = base::StringPrintf("%d", num_pending_io_);
-  stats->push_back(item);
-
-  item.first = "Max size";
-  item.second = base::StringPrintf("%d", max_size_);
-  stats->push_back(item);
-
-  item.first = "Current size";
-  item.second = base::StringPrintf("%d", data_->header.num_bytes);
-  stats->push_back(item);
-
-  item.first = "Cache type";
-  item.second = "Blockfile Cache";
-  stats->push_back(item);
-
-  stats_.GetItems(stats);
-}
-
-void BackendImpl::OnExternalCacheHit(const std::string& key) {
-  background_queue_.OnExternalCacheHit(key);
-}
-
-// ------------------------------------------------------------------------
-
 // 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) {
@@ -1321,661 +371,16 @@
   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) {
-  if (max_size_)
-    return;
+void BackendImpl::ReportError(int error) {
+  STRESS_DCHECK(!error || error == ERR_PREVIOUS_CRASH ||
+                error == ERR_CACHE_CREATED);
 
-  // If table_len is provided, the index file exists.
-  DCHECK(!table_len || data_->header.magic);
-
-  // The user is not setting the size, let's figure it out.
-  int64 available = base::SysInfo::AmountOfFreeDiskSpace(path_);
-  if (available < 0) {
-    max_size_ = kDefaultCacheSize;
-    return;
-  }
-
-  if (table_len)
-    available += data_->header.num_bytes;
-
-  max_size_ = PreferedCacheSize(available);
-
-  // Let's not use more than the default size while we tune-up the performance
-  // of bigger caches. TODO(rvargas): remove this limit.
-  if (max_size_ > kDefaultCacheSize * 4)
-    max_size_ = kDefaultCacheSize * 4;
-
-  if (!table_len)
-    return;
-
-  // If we already have a table, adjust the size to it.
-  int current_max_size = MaxStorageSizeForTable(table_len);
-  if (max_size_ > current_max_size)
-    max_size_= current_max_size;
+  // We transmit positive numbers, instead of direct error codes.
+  DCHECK_LE(error, 0);
+  CACHE_UMA(CACHE_ERROR, "Error", 0, error * -1);
 }
 
-bool BackendImpl::InitStats() {
-  Addr address(data_->header.stats);
-  int size = stats_.StorageSize();
 
-  if (!address.is_initialized()) {
-    FileType file_type = Addr::RequiredFileType(size);
-    DCHECK_NE(file_type, EXTERNAL);
-    int num_blocks = Addr::RequiredBlocks(size, file_type);
-
-    if (!CreateBlock(file_type, num_blocks, &address))
-      return false;
-    return stats_.Init(NULL, 0, address);
-  }
-
-  if (!address.is_block_file()) {
-    NOTREACHED();
-    return false;
-  }
-
-  // Load the required data.
-  size = address.num_blocks() * address.BlockSize();
-  MappedFile* file = File(address);
-  if (!file)
-    return false;
-
-  scoped_ptr<char[]> data(new char[size]);
-  size_t offset = address.start_block() * address.BlockSize() +
-                  kBlockHeaderSize;
-  if (!file->Read(data.get(), size, offset))
-    return false;
-
-  if (!stats_.Init(data.get(), size, address))
-    return false;
-  if (cache_type_ == net::DISK_CACHE && ShouldReportAgain())
-    stats_.InitSizeHistogram();
-  return true;
-}
-
-void BackendImpl::StoreStats() {
-  int size = stats_.StorageSize();
-  scoped_ptr<char[]> data(new char[size]);
-  Addr address;
-  size = stats_.SerializeStats(data.get(), size, &address);
-  DCHECK(size);
-  if (!address.is_initialized())
-    return;
-
-  MappedFile* file = File(address);
-  if (!file)
-    return;
-
-  size_t offset = address.start_block() * address.BlockSize() +
-                  kBlockHeaderSize;
-  file->Write(data.get(), size, offset);  // ignore result.
-}
-
-void BackendImpl::RestartCache(bool failure) {
-  int64 errors = stats_.GetCounter(Stats::FATAL_ERROR);
-  int64 full_dooms = stats_.GetCounter(Stats::DOOM_CACHE);
-  int64 partial_dooms = stats_.GetCounter(Stats::DOOM_RECENT);
-  int64 last_report = stats_.GetCounter(Stats::LAST_REPORT);
-
-  PrepareForRestart();
-  if (failure) {
-    DCHECK(!num_refs_);
-    DCHECK(!open_entries_.size());
-    DelayedCacheCleanup(path_);
-  } else {
-    DeleteCache(path_, false);
-  }
-
-  // Don't call Init() if directed by the unit test: we are simulating a failure
-  // trying to re-enable the cache.
-  if (unit_test_)
-    init_ = true;  // Let the destructor do proper cleanup.
-  else if (SyncInit() == net::OK) {
-    stats_.SetCounter(Stats::FATAL_ERROR, errors);
-    stats_.SetCounter(Stats::DOOM_CACHE, full_dooms);
-    stats_.SetCounter(Stats::DOOM_RECENT, partial_dooms);
-    stats_.SetCounter(Stats::LAST_REPORT, last_report);
-  }
-}
-
-void BackendImpl::PrepareForRestart() {
-  // Reset the mask_ if it was not given by the user.
-  if (!(user_flags_ & kMask))
-    mask_ = 0;
-
-  if (!(user_flags_ & kNewEviction))
-    new_eviction_ = false;
-
-  disabled_ = true;
-  data_->header.crash = 0;
-  index_->Flush();
-  index_ = NULL;
-  data_ = NULL;
-  block_files_.CloseFiles();
-  rankings_.Reset();
-  init_ = false;
-  restarted_ = true;
-}
-
-int BackendImpl::NewEntry(Addr address, EntryImpl** entry) {
-  EntriesMap::iterator it = open_entries_.find(address.value());
-  if (it != open_entries_.end()) {
-    // Easy job. This entry is already in memory.
-    EntryImpl* this_entry = it->second;
-    this_entry->AddRef();
-    *entry = this_entry;
-    return 0;
-  }
-
-  STRESS_DCHECK(block_files_.IsValid(address));
-
-  if (!address.SanityCheckForEntry()) {
-    LOG(WARNING) << "Wrong entry address.";
-    STRESS_NOTREACHED();
-    return ERR_INVALID_ADDRESS;
-  }
-
-  scoped_refptr<EntryImpl> cache_entry(
-      new EntryImpl(this, address, read_only_));
-  IncreaseNumRefs();
-  *entry = NULL;
-
-  TimeTicks start = TimeTicks::Now();
-  if (!cache_entry->entry()->Load())
-    return ERR_READ_FAILURE;
-
-  if (IsLoaded()) {
-    CACHE_UMA(AGE_MS, "LoadTime", 0, start);
-  }
-
-  if (!cache_entry->SanityCheck()) {
-    LOG(WARNING) << "Messed up entry found.";
-    STRESS_NOTREACHED();
-    return ERR_INVALID_ENTRY;
-  }
-
-  STRESS_DCHECK(block_files_.IsValid(
-                    Addr(cache_entry->entry()->Data()->rankings_node)));
-
-  if (!cache_entry->LoadNodeAddress())
-    return ERR_READ_FAILURE;
-
-  if (!rankings_.SanityCheck(cache_entry->rankings(), false)) {
-    STRESS_NOTREACHED();
-    cache_entry->SetDirtyFlag(0);
-    // Don't remove this from the list (it is not linked properly). Instead,
-    // break the link back to the entry because it is going away, and leave the
-    // rankings node to be deleted if we find it through a list.
-    rankings_.SetContents(cache_entry->rankings(), 0);
-  } else if (!rankings_.DataSanityCheck(cache_entry->rankings(), false)) {
-    STRESS_NOTREACHED();
-    cache_entry->SetDirtyFlag(0);
-    rankings_.SetContents(cache_entry->rankings(), address.value());
-  }
-
-  if (!cache_entry->DataSanityCheck()) {
-    LOG(WARNING) << "Messed up entry found.";
-    cache_entry->SetDirtyFlag(0);
-    cache_entry->FixForDelete();
-  }
-
-  // Prevent overwriting the dirty flag on the destructor.
-  cache_entry->SetDirtyFlag(GetCurrentEntryId());
-
-  if (cache_entry->dirty()) {
-    Trace("Dirty entry 0x%p 0x%x", reinterpret_cast<void*>(cache_entry.get()),
-          address.value());
-  }
-
-  open_entries_[address.value()] = cache_entry.get();
-
-  cache_entry->BeginLogging(net_log_, false);
-  cache_entry.swap(entry);
-  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_)
-    return NULL;
-
-  DCHECK(iter);
-
-  const int kListsToSearch = 3;
-  scoped_refptr<EntryImpl> entries[kListsToSearch];
-  scoped_ptr<Rankings::Iterator> iterator(
-      reinterpret_cast<Rankings::Iterator*>(*iter));
-  *iter = NULL;
-
-  if (!iterator.get()) {
-    iterator.reset(new Rankings::Iterator(&rankings_));
-    bool ret = false;
-
-    // Get an entry from each list.
-    for (int i = 0; i < kListsToSearch; i++) {
-      EntryImpl* temp = NULL;
-      ret |= OpenFollowingEntryFromList(forward, static_cast<Rankings::List>(i),
-                                        &iterator->nodes[i], &temp);
-      entries[i].swap(&temp);  // The entry was already addref'd.
-    }
-    if (!ret)
-      return NULL;
-  } else {
-    // Get the next entry from the last list, and the actual entries for the
-    // elements on the other lists.
-    for (int i = 0; i < kListsToSearch; i++) {
-      EntryImpl* temp = NULL;
-      if (iterator->list == i) {
-          OpenFollowingEntryFromList(forward, iterator->list,
-                                     &iterator->nodes[i], &temp);
-      } else {
-        temp = GetEnumeratedEntry(iterator->nodes[i],
-                                  static_cast<Rankings::List>(i));
-      }
-
-      entries[i].swap(&temp);  // The entry was already addref'd.
-    }
-  }
-
-  int newest = -1;
-  int oldest = -1;
-  Time access_times[kListsToSearch];
-  for (int i = 0; i < kListsToSearch; i++) {
-    if (entries[i].get()) {
-      access_times[i] = entries[i]->GetLastUsed();
-      if (newest < 0) {
-        DCHECK_LT(oldest, 0);
-        newest = oldest = i;
-        continue;
-      }
-      if (access_times[i] > access_times[newest])
-        newest = i;
-      if (access_times[i] < access_times[oldest])
-        oldest = i;
-    }
-  }
-
-  if (newest < 0 || oldest < 0)
-    return NULL;
-
-  EntryImpl* next_entry;
-  if (forward) {
-    next_entry = entries[newest].get();
-    iterator->list = static_cast<Rankings::List>(newest);
-  } else {
-    next_entry = entries[oldest].get();
-    iterator->list = static_cast<Rankings::List>(oldest);
-  }
-
-  *iter = iterator.release();
-  next_entry->AddRef();
-  return next_entry;
-}
-
-bool BackendImpl::OpenFollowingEntryFromList(bool forward, Rankings::List list,
-                                             CacheRankingsBlock** from_entry,
-                                             EntryImpl** next_entry) {
-  if (disabled_)
-    return false;
-
-  if (!new_eviction_ && Rankings::NO_USE != list)
-    return false;
-
-  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;
-
-  *next_entry = GetEnumeratedEntry(next.get(), list);
-  if (!*next_entry)
-    return false;
-
-  *from_entry = next.release();
-  return true;
-}
-
-EntryImpl* BackendImpl::GetEnumeratedEntry(CacheRankingsBlock* next,
-                                           Rankings::List list) {
-  if (!next || disabled_)
-    return NULL;
-
-  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;
-  }
-
-  if (entry->dirty()) {
-    // We cannot trust this entry.
-    InternalDoomEntry(entry);
-    entry->Release();
-    return NULL;
-  }
-
-  if (!entry->Update()) {
-    STRESS_NOTREACHED();
-    entry->Release();
-    return NULL;
-  }
-
-  // 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.
-
-  // Make sure that we save the key for later.
-  entry->GetKey();
-
-  return entry;
-}
-
-EntryImpl* BackendImpl::ResurrectEntry(EntryImpl* deleted_entry) {
-  if (ENTRY_NORMAL == deleted_entry->entry()->Data()->state) {
-    deleted_entry->Release();
-    stats_.OnEvent(Stats::CREATE_MISS);
-    Trace("create entry miss ");
-    return NULL;
-  }
-
-  // We are attempting to create an entry and found out that the entry was
-  // previously deleted.
-
-  eviction_.OnCreateEntry(deleted_entry);
-  entry_count_++;
-
-  stats_.OnEvent(Stats::RESURRECT_HIT);
-  Trace("Resurrect entry hit ");
-  return deleted_entry;
-}
-
-void BackendImpl::DestroyInvalidEntry(EntryImpl* entry) {
-  LOG(WARNING) << "Destroying invalid entry.";
-  Trace("Destroying invalid entry 0x%p", entry);
-
-  entry->SetPointerForInvalidEntry(GetCurrentEntryId());
-
-  eviction_.OnDoomEntry(entry);
-  entry->InternalDoom();
-
-  if (!new_eviction_)
-    DecreaseNumEntries();
-  stats_.OnEvent(Stats::INVALID_ENTRY);
-}
-
-void BackendImpl::AddStorageSize(int32 bytes) {
-  data_->header.num_bytes += bytes;
-  DCHECK_GE(data_->header.num_bytes, 0);
-}
-
-void BackendImpl::SubstractStorageSize(int32 bytes) {
-  data_->header.num_bytes -= bytes;
-  DCHECK_GE(data_->header.num_bytes, 0);
-}
-
-void BackendImpl::IncreaseNumRefs() {
-  num_refs_++;
-  if (max_refs_ < num_refs_)
-    max_refs_ = num_refs_;
-}
-
-void BackendImpl::DecreaseNumRefs() {
-  DCHECK(num_refs_);
-  num_refs_--;
-
-  if (!num_refs_ && disabled_)
-    base::MessageLoop::current()->PostTask(
-        FROM_HERE, base::Bind(&BackendImpl::RestartCache, GetWeakPtr(), true));
-}
-
-void BackendImpl::IncreaseNumEntries() {
-  data_->header.num_entries++;
-  DCHECK_GT(data_->header.num_entries, 0);
-}
-
-void BackendImpl::DecreaseNumEntries() {
-  data_->header.num_entries--;
-  if (data_->header.num_entries < 0) {
-    NOTREACHED();
-    data_->header.num_entries = 0;
-  }
-}
-
-void BackendImpl::LogStats() {
-  StatsItems stats;
-  GetStats(&stats);
-
-  for (size_t index = 0; index < stats.size(); index++)
-    VLOG(1) << stats[index].first << ": " << stats[index].second;
-}
-
-void BackendImpl::ReportStats() {
-  CACHE_UMA(COUNTS, "Entries", 0, data_->header.num_entries);
-
-  int current_size = data_->header.num_bytes / (1024 * 1024);
-  int max_size = max_size_ / (1024 * 1024);
-  int hit_ratio_as_percentage = stats_.GetHitRatio();
-
-  CACHE_UMA(COUNTS_10000, "Size2", 0, current_size);
-  // For any bin in HitRatioBySize2, the hit ratio of caches of that size is the
-  // ratio of that bin's total count to the count in the same bin in the Size2
-  // histogram.
-  if (base::RandInt(0, 99) < hit_ratio_as_percentage)
-    CACHE_UMA(COUNTS_10000, "HitRatioBySize2", 0, current_size);
-  CACHE_UMA(COUNTS_10000, "MaxSize2", 0, max_size);
-  if (!max_size)
-    max_size++;
-  CACHE_UMA(PERCENTAGE, "UsedSpace", 0, current_size * 100 / max_size);
-
-  CACHE_UMA(COUNTS_10000, "AverageOpenEntries2", 0,
-            static_cast<int>(stats_.GetCounter(Stats::OPEN_ENTRIES)));
-  CACHE_UMA(COUNTS_10000, "MaxOpenEntries2", 0,
-            static_cast<int>(stats_.GetCounter(Stats::MAX_ENTRIES)));
-  stats_.SetCounter(Stats::MAX_ENTRIES, 0);
-
-  CACHE_UMA(COUNTS_10000, "TotalFatalErrors", 0,
-            static_cast<int>(stats_.GetCounter(Stats::FATAL_ERROR)));
-  CACHE_UMA(COUNTS_10000, "TotalDoomCache", 0,
-            static_cast<int>(stats_.GetCounter(Stats::DOOM_CACHE)));
-  CACHE_UMA(COUNTS_10000, "TotalDoomRecentEntries", 0,
-            static_cast<int>(stats_.GetCounter(Stats::DOOM_RECENT)));
-  stats_.SetCounter(Stats::FATAL_ERROR, 0);
-  stats_.SetCounter(Stats::DOOM_CACHE, 0);
-  stats_.SetCounter(Stats::DOOM_RECENT, 0);
-
-  int64 total_hours = stats_.GetCounter(Stats::TIMER) / 120;
-  if (!data_->header.create_time || !data_->header.lru.filled) {
-    int cause = data_->header.create_time ? 0 : 1;
-    if (!data_->header.lru.filled)
-      cause |= 2;
-    CACHE_UMA(CACHE_ERROR, "ShortReport", 0, cause);
-    CACHE_UMA(HOURS, "TotalTimeNotFull", 0, static_cast<int>(total_hours));
-    return;
-  }
-
-  // This is an up to date client that will report FirstEviction() data. After
-  // that event, start reporting this:
-
-  CACHE_UMA(HOURS, "TotalTime", 0, static_cast<int>(total_hours));
-  // For any bin in HitRatioByTotalTime, the hit ratio of caches of that total
-  // time is the ratio of that bin's total count to the count in the same bin in
-  // the TotalTime histogram.
-  if (base::RandInt(0, 99) < hit_ratio_as_percentage)
-    CACHE_UMA(HOURS, "HitRatioByTotalTime", 0, implicit_cast<int>(total_hours));
-
-  int64 use_hours = stats_.GetCounter(Stats::LAST_REPORT_TIMER) / 120;
-  stats_.SetCounter(Stats::LAST_REPORT_TIMER, stats_.GetCounter(Stats::TIMER));
-
-  // We may see users with no use_hours at this point if this is the first time
-  // we are running this code.
-  if (use_hours)
-    use_hours = total_hours - use_hours;
-
-  if (!use_hours || !GetEntryCount() || !data_->header.num_bytes)
-    return;
-
-  CACHE_UMA(HOURS, "UseTime", 0, static_cast<int>(use_hours));
-  // For any bin in HitRatioByUseTime, the hit ratio of caches of that use time
-  // is the ratio of that bin's total count to the count in the same bin in the
-  // UseTime histogram.
-  if (base::RandInt(0, 99) < hit_ratio_as_percentage)
-    CACHE_UMA(HOURS, "HitRatioByUseTime", 0, implicit_cast<int>(use_hours));
-  CACHE_UMA(PERCENTAGE, "HitRatio", 0, hit_ratio_as_percentage);
-
-  int64 trim_rate = stats_.GetCounter(Stats::TRIM_ENTRY) / use_hours;
-  CACHE_UMA(COUNTS, "TrimRate", 0, static_cast<int>(trim_rate));
-
-  int avg_size = data_->header.num_bytes / GetEntryCount();
-  CACHE_UMA(COUNTS, "EntrySize", 0, avg_size);
-  CACHE_UMA(COUNTS, "EntriesFull", 0, data_->header.num_entries);
-
-  CACHE_UMA(PERCENTAGE, "IndexLoad", 0,
-            data_->header.num_entries * 100 / (mask_ + 1));
-
-  int large_entries_bytes = stats_.GetLargeEntriesSize();
-  int large_ratio = large_entries_bytes * 100 / data_->header.num_bytes;
-  CACHE_UMA(PERCENTAGE, "LargeEntriesRatio", 0, large_ratio);
-
-  if (new_eviction_) {
-    CACHE_UMA(PERCENTAGE, "ResurrectRatio", 0, stats_.GetResurrectRatio());
-    CACHE_UMA(PERCENTAGE, "NoUseRatio", 0,
-              data_->header.lru.sizes[0] * 100 / data_->header.num_entries);
-    CACHE_UMA(PERCENTAGE, "LowUseRatio", 0,
-              data_->header.lru.sizes[1] * 100 / data_->header.num_entries);
-    CACHE_UMA(PERCENTAGE, "HighUseRatio", 0,
-              data_->header.lru.sizes[2] * 100 / data_->header.num_entries);
-    CACHE_UMA(PERCENTAGE, "DeletedRatio", 0,
-              data_->header.lru.sizes[4] * 100 / data_->header.num_entries);
-  }
-
-  stats_.ResetRatios();
-  stats_.SetCounter(Stats::TRIM_ENTRY, 0);
-
-  if (cache_type_ == net::DISK_CACHE)
-    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;
-}
-
 bool BackendImpl::CheckIndex() {
   DCHECK(data_);
 
@@ -2039,80 +444,42 @@
   return index_->Read(buf.get(), current_size, 0);
 }
 
-int BackendImpl::CheckAllEntries() {
-  int num_dirty = 0;
-  int num_entries = 0;
-  DCHECK(mask_ < kuint32max);
-  for (unsigned int i = 0; i <= mask_; i++) {
-    Addr address(data_->table[i]);
-    if (!address.is_initialized())
-      continue;
-    for (;;) {
-      EntryImpl* tmp;
-      int ret = NewEntry(address, &tmp);
-      if (ret) {
-        STRESS_NOTREACHED();
-        return ret;
-      }
-      scoped_refptr<EntryImpl> cache_entry;
-      cache_entry.swap(&tmp);
+bool BackendImpl::InitStats() {
+  Addr address(data_->header.stats);
+  int size = stats_.StorageSize();
 
-      if (cache_entry->dirty())
-        num_dirty++;
-      else if (CheckEntry(cache_entry.get()))
-        num_entries++;
-      else
-        return ERR_INVALID_ENTRY;
+  if (!address.is_initialized()) {
+    FileType file_type = Addr::RequiredFileType(size);
+    DCHECK_NE(file_type, EXTERNAL);
+    int num_blocks = Addr::RequiredBlocks(size, file_type);
 
-      DCHECK_EQ(i, cache_entry->entry()->Data()->hash & mask_);
-      address.set_value(cache_entry->GetNextAddress());
-      if (!address.is_initialized())
-        break;
-    }
+    if (!CreateBlock(file_type, num_blocks, &address))
+      return false;
+    return stats_.Init(NULL, 0, address);
   }
 
-  Trace("CheckAllEntries End");
-  if (num_entries + num_dirty != data_->header.num_entries) {
-    LOG(ERROR) << "Number of entries " << num_entries << " " << num_dirty <<
-                  " " << data_->header.num_entries;
-    DCHECK_LT(num_entries, data_->header.num_entries);
-    return ERR_NUM_ENTRIES_MISMATCH;
+  if (!address.is_block_file()) {
+    NOTREACHED();
+    return false;
   }
 
-  return num_dirty;
-}
+  // Load the required data.
+  size = address.num_blocks() * address.BlockSize();
+  MappedFile* file = File(address);
+  if (!file)
+    return false;
 
-bool BackendImpl::CheckEntry(EntryImpl* cache_entry) {
-  bool ok = block_files_.IsValid(cache_entry->entry()->address());
-  ok = ok && block_files_.IsValid(cache_entry->rankings()->address());
-  EntryStore* data = cache_entry->entry()->Data();
-  for (size_t i = 0; i < arraysize(data->data_addr); i++) {
-    if (data->data_addr[i]) {
-      Addr address(data->data_addr[i]);
-      if (address.is_block_file())
-        ok = ok && block_files_.IsValid(address);
-    }
-  }
+  scoped_ptr<char[]> data(new char[size]);
+  size_t offset = address.start_block() * address.BlockSize() +
+                  kBlockHeaderSize;
+  if (!file->Read(data.get(), size, offset))
+    return false;
 
-  return ok && cache_entry->rankings()->VerifyHash();
+  if (!stats_.Init(data.get(), size, address))
+    return false;
+  if (cache_type_ == net::DISK_CACHE && ShouldReportAgain())
+    stats_.InitSizeHistogram();
+  return true;
 }
 
-int BackendImpl::MaxBuffersSize() {
-  static int64 total_memory = base::SysInfo::AmountOfPhysicalMemory();
-  static bool done = false;
-
-  if (!done) {
-    const int kMaxBuffersSize = 30 * 1024 * 1024;
-
-    // We want to use up to 2% of the computer's memory.
-    total_memory = total_memory * 2 / 100;
-    if (total_memory > kMaxBuffersSize || total_memory <= 0)
-      total_memory = kMaxBuffersSize;
-
-    done = true;
-  }
-
-  return static_cast<int>(total_memory);
-}
-
 }  // namespace disk_cache