Disk cache v3 ref2

net/disk_cache/v3/backend_worker.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "net/disk_cache/backend_impl.h"
+#include "net/disk_cache/v3/backend_worker.h"
 
 #include "base/bind.h"
-#include "base/bind_helpers.h"
 #include "base/file_util.h"
-#include "base/files/file_path.h"
-#include "base/hash.h"
 #include "base/message_loop/message_loop.h"
-#include "base/metrics/field_trial.h"
-#include "base/metrics/histogram.h"
-#include "base/metrics/stats_counters.h"
-#include "base/rand_util.h"
-#include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
-#include "base/sys_info.h"
-#include "base/threading/thread_restrictions.h"
-#include "base/time/time.h"
-#include "base/timer/timer.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/cache_util.h"
-#include "net/disk_cache/entry_impl.h"
 #include "net/disk_cache/errors.h"
 #include "net/disk_cache/experiments.h"
-#include "net/disk_cache/file.h"
-
-// This has to be defined before including histogram_macros.h from this file.
-#define NET_DISK_CACHE_BACKEND_IMPL_CC_
-#include "net/disk_cache/histogram_macros.h"
+#include "net/disk_cache/mapped_file.h"
+#include "net/disk_cache/v3/backend_work_item.h"
+#include "net/disk_cache/v3/disk_format_v3.h"
 
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
 
 namespace {
 
-const char* kIndexName = "index";
+const char kIndexName[] = "index";
+const char kIndexBackupName[] = "index_bak";
+const char kTable1Name[] = "index_tb1";
+const char kTable2Name[] = "index_tb2";
+const char kTable2TempName[] = "index_tb2_tmp";
+const int kMaxOldFolders = 100;
 
 // Seems like ~240 MB correspond to less than 50k entries for 99% of the people.
 // Note that the actual target is to keep the index table load factor under 55%
 // for most users.
 const int k64kEntriesStore = 240 * 1000 * 1000;
 const int kBaseTableLen = 64 * 1024;
 const int kDefaultCacheSize = 80 * 1024 * 1024;
 
 // Avoid trimming the cache for the first 5 minutes (10 timer ticks).
 const int kTrimDelay = 10;
@@ skipping 10 matching lines @@
 
   // The biggest storage_size for int32 requires a 4 MB table.
   return kBaseTableLen * 16;
 }
 
 int MaxStorageSizeForTable(int table_len) {
   return table_len * (k64kEntriesStore / kBaseTableLen);
 }
 
 size_t GetIndexSize(int table_len) {
-  size_t table_size = sizeof(disk_cache::CacheAddr) * table_len;
-  return sizeof(disk_cache::IndexHeader) + table_size;
+  //  
+  //size_t table_size = sizeof(disk_cache::CacheAddr) * table_len;
+  //return sizeof(disk_cache::IndexHeaderV3) + table_size;
+  return 0;
+}
+
+size_t GetIndexBitmapSize(int table_len) {
+  DCHECK_LT(table_len, 1 << 22);
+  size_t base_bits = disk_cache::kBaseBitmapBytes * 8;
+  if (table_len < static_cast<int>(base_bits))
+    return sizeof(disk_cache::IndexBitmap);
+
+  size_t extra_pages = (table_len / 8) - disk_cache::kBaseBitmapBytes;
+  extra_pages = (extra_pages + 4095) / 4096;
+  return sizeof(disk_cache::IndexBitmap) + extra_pages * 4096;
 }
 
 // ------------------------------------------------------------------------
 
 // 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;
-    }
-  }
-
+bool InitExperiment(disk_cache::IndexHeaderV3* header) {
   header->experiment = disk_cache::NO_EXPERIMENT;
   return true;
 }
 
 }  // namespace
 
 // ------------------------------------------------------------------------
 
 namespace disk_cache {
 
-BackendImpl::BackendImpl(const base::FilePath& path,
-                         base::MessageLoopProxy* cache_thread,
-                         net::NetLog* net_log)
-    : background_queue_(this, cache_thread),
-      path_(path),
-      block_files_(path),
-      mask_(0),
-      max_size_(0),
-      up_ticks_(0),
-      cache_type_(net::DISK_CACHE),
-      uma_report_(0),
-      user_flags_(0),
-      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) {
-}
-
-int BackendImpl::SyncInit() {
-#if defined(NET_BUILD_STRESS_CACHE)
-  // Start evictions right away.
-  up_ticks_ = kTrimDelay * 2;
-#endif
+BackendImplV3::Worker::Worker(const base::FilePath& path,
+                              base::MessageLoopProxy* main_thread)
+      : path_(path),
+        main_thread_(main_thread),
+        cleanup_work_item_(NULL),
+        init_(false),
+        doubling_index_(false),
+        user_flags_(0) {
+}
+
+int BackendImplV3::Worker::Init(uint32 flags, scoped_ptr<InitResult>* result) {
   DCHECK(!init_);
   if (init_)
-    return net::ERR_FAILED;
+    return ERR_INIT_FAILED;
+
+  user_flags_ = flags;
+  result->reset(new InitResult);
 
   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);
-  }
+  if (!InitBackingStore(&create_files))
+    return ERR_STORAGE_ERROR;
 
   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 (!LoadIndex(result->get()))
+    return ERR_INIT_FAILED;
+
+  int rv = ERR_NO_ERROR;
+  IndexHeaderV3* index =
+      reinterpret_cast<IndexHeaderV3*>(index_header_->buffer());
+  if (create_files || !index->num_entries)
+    rv = ERR_CACHE_CREATED;
+
+  if (create_files && (flags & EVICTION_V2)) {
+    index->flags |= CACHE_EVICTION_2;
+  }
+
+  if (!(flags & BASIC_UNIT_TEST) && !InitExperiment(index))
+    return ERR_INIT_FAILED;
+
+  if (index->crash != 0)
+    rv = ERR_PREVIOUS_CRASH;
+  index->crash = 1;
+
+  block_files_.reset(new BlockFiles(path_));
+  if (flags & BASIC_UNIT_TEST)
+    block_files_->UseSmallSizeIncrementsForTest();
+
+  if (!block_files_->Init(create_files, kFirstAdditionalBlockFileV3))
+    return ERR_INIT_FAILED;
+
+  block_files_->GetBitmaps(index->max_block_file,
+                           &result->get()->block_bitmaps);
+  index->max_block_file = static_cast<int>(result->get()->block_bitmaps.size());
+
+  if (!InitStats(index, result->get()))
+    return ERR_INIT_FAILED;
 
 #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::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();
+  return rv;
+}
+
+int BackendImplV3::Worker::Restart(uint32 flags,
+                                   scoped_ptr<InitResult>* result) {
+  Trace("Worker::Restart");
+  if (init_) {
+    init_ = false;
+  }
+
+  CloseFiles();
+  DeleteCache(path_, false);
+
+  return Init(flags, result);
+}
+
+int BackendImplV3::Worker::GrowIndex(uint32 flags,
+                                     scoped_ptr<InitResult>* result) {
+  Trace("Worker::GrowIndex, flags 0x%x", flags);
+  if (!init_)
+    return ERR_OPERATION_FAILED;
+
+  if (flags & WorkItem::WORK_COMPLETE) {
+    index_header_ = big_index_header_;
+    big_index_header_ = NULL;
+    if (big_main_table_) {
+      main_table_ = big_main_table_;
+      big_main_table_ = NULL;
+    }
+    if (!big_extra_temp_table_)
+      extra_table_ = big_extra_table_;
+    big_extra_table_ = NULL;
+
+    // If the index takes time to move the cells, it creates a new work item to
+    // notify completion, which executes this code.
+    if (big_extra_temp_table_)
+      return GrowDone();
+
+    return ERR_NO_ERROR;
+  }
+
+  IndexHeaderV3* header =
+      reinterpret_cast<IndexHeaderV3*>(index_header_->buffer());
+
+  int current_main_len = header->table_len / kBaseTableLen * kBaseTableLen;
+  int step_size = std::min(8192, current_main_len / 8);
+  if (user_flags_ & BASIC_UNIT_TEST)
+    step_size = 8;
+  if ((user_flags_ & UNIT_TEST_MODE) && !doubling_index_)
+    step_size = (header->table_len * 3 / 2) & 0x7ffffff0;
+  int new_len = header->table_len + step_size;
+
+  bool double_index = false;
+  if (!doubling_index_) {
+    DCHECK(!big_extra_table_);
+    DCHECK(!big_main_table_);
+    double_index = (new_len / kBaseTableLen !=
+                    header->table_len / kBaseTableLen);
+  }
+
+  int extra_len = new_len - kBaseTableLen;
+  if (double_index) {
+    // We double the table when the extra table is about to reach the size of
+    // the main table. That means that right after this, the new extra table
+    // should be between 19% and 23% of the main table so we start with 25%.
+    extra_len = std::min(8192, current_main_len / 4);
+    extra_len = (user_flags_ & BASIC_UNIT_TEST) ? 128 : extra_len;
+    int main_len = (header->table_len / kBaseTableLen + 1) * kBaseTableLen;
+    new_len = main_len + extra_len;
+
+    if (!CreateExtraTable(extra_len * kBytesPerCell))
+      return ERR_OPERATION_FAILED;
+
+    if (!main_table_->SetLength(main_len * kBytesPerCell))
+      return ERR_OPERATION_FAILED;
+  } else if (doubling_index_) {
+    if (!big_extra_temp_table_->SetLength(extra_len * kBytesPerCell))
+      return ERR_OPERATION_FAILED;
+  } else {
+    if (!extra_table_->SetLength(extra_len * kBytesPerCell))
+      return ERR_OPERATION_FAILED;
+  }
+
+  if (!index_header_->SetLength(GetIndexBitmapSize(new_len)))
+    return ERR_OPERATION_FAILED;
+
+  scoped_refptr<MappedFile> big_index_header = new MappedFile();
+  if (!big_index_header->Init(path_.AppendASCII(kIndexName), 0)) {
+    LOG(ERROR) << "Unable to remap index";
+    return ERR_OPERATION_FAILED;
+  }
+
+  scoped_refptr<MappedFile> big_extra_table = new MappedFile();
+  const char* extra_name = (double_index || doubling_index_) ? kTable2TempName :
+                                                               kTable2Name;
+  if (!big_extra_table->Init(path_.AppendASCII(extra_name), 0)) {
+    LOG(ERROR) << "Unable to remap index_tb2";
+    return ERR_OPERATION_FAILED;
+  }
+
+  if (double_index) {
+    scoped_refptr<MappedFile> big_main_table = new MappedFile();
+    if (!big_main_table->Init(path_.AppendASCII(kTable1Name), 0)) {
+      LOG(ERROR) << "Unable to remap index_tb1";
+      return ERR_OPERATION_FAILED;
+    }
+    big_main_table_.swap(big_main_table);
+
+    // Grab an extra reference to the new extra table that can be used for an
+    // extended period, while the index is being rebuilt. The normal reference
+    // (big_extra_table_) will be released when the work item is completed, but
+    // that doesn't mean the index is done with it.
+    // Note that we are able to process slow grow requests even when the index
+    // is being doubled.
+    big_extra_temp_table_ = big_extra_table;
+  }
+  big_index_header_.swap(big_index_header);
+  big_extra_table_.swap(big_extra_table);
+
+  header = reinterpret_cast<IndexHeaderV3*>(big_index_header_->buffer());
+  header->table_len = new_len;
+
+  result->reset(new InitResult);
+  result->get()->index_data.main_table = NULL;
+
+  result->get()->index_data.index_bitmap =
+      reinterpret_cast<IndexBitmap*>(big_index_header_->buffer());
+  result->get()->index_data.extra_table =
+      reinterpret_cast<IndexBucket*>(big_extra_table_->buffer());
+
+  if (double_index) {
+    result->get()->index_data.main_table =
+      reinterpret_cast<IndexBucket*>(big_main_table_->buffer());
+    doubling_index_ = true;
+  }
+
+  return ERR_NO_ERROR;
+}
+
+int BackendImplV3::Worker::GrowFiles(uint32 flags,
+                                     scoped_ptr<InitResult>* result) {
+  Trace("Worker::GrowFiles, flags 0x%x", flags);
+  if (!init_)
+    return ERR_OPERATION_FAILED;
+
+  if (flags & WorkItem::WORK_COMPLETE) {
+    block_files_.reset();
+    block_files_.swap(big_block_files_);
+    return ERR_NO_ERROR;
+  }
+
+  big_block_files_.reset(new BlockFiles(path_));
+  if (user_flags_ & BASIC_UNIT_TEST)
+    big_block_files_->UseSmallSizeIncrementsForTest();
+
+  if (!big_block_files_->Init(false, kFirstAdditionalBlockFileV3))
+    return ERR_INIT_FAILED;
+
+  IndexHeaderV3* index =
+      reinterpret_cast<IndexHeaderV3*>(index_header_->buffer());
+
+  result->reset(new InitResult);
+  big_block_files_->GetBitmaps(index->max_block_file,
+                               &result->get()->block_bitmaps);
+  index->max_block_file = static_cast<int>(result->get()->block_bitmaps.size());
+  return ERR_NO_ERROR;
+}
+
+int BackendImplV3::Worker::Delete(Addr address) {
+  if (address.is_block_file())
+    return ERR_OPERATION_FAILED;
+
+  if (DeleteCacheFile(GetFileName(address))) 
+    return ERR_NO_ERROR;
+
+  return ERR_OPERATION_FAILED;
+}
+
+int BackendImplV3::Worker::Close(Addr address) {
+  if (address.is_block_file())
+    return ERR_OPERATION_FAILED;
+
+  FilesMap::iterator it = files_.find(address.value());
+  if (it != files_.end())
+    files_.erase(it);
+
+  return ERR_NO_ERROR;
+}
+
+void BackendImplV3::Worker::OnDoWork(WorkItem* work_item) {
+  if (work_item->type() == WorkItem::WORK_CLEANUP)
+    return Cleanup(work_item);
+
+  work_item->Start(this);
+}
+
+void BackendImplV3::Worker::DoneWithItem(WorkItem* work_item) {
+  bool rv = main_thread_->PostTask(FROM_HERE,
+                                   base::Bind(&WorkItem::OnDone, work_item));
+  DCHECK(rv);
+}
+
+File* BackendImplV3::Worker::GetBackingFile(Addr address, bool for_write) {
+  disk_cache::File* file;
+  if (address.is_separate_file())
+    file = GetExternalFile(address, for_write);
+  else
+    file = block_files_->GetFile(address);
+  return file;
+}
+
+File* BackendImplV3::Worker::GetBackupIndexFile() {
+  DCHECK(!index_backup_.get());
+  index_backup_ = new MappedFile();
+  index_backup_->set_force_creation();
+  if (!index_backup_->InitNoMap(path_.AppendASCII(kIndexBackupName))) {
+    LOG(ERROR) << "Unable to open index_bak";
+    return NULL;
+  }
+  return index_backup_.get();
+}
+
+void BackendImplV3::Worker::CloseBackupIndexFile() {
+  index_backup_ = NULL;
+}
+
+bool BackendImplV3::Worker::IsValid() {
+  return init_;
+}
+
+// ------------------------------------------------------------------------
+
+BackendImplV3::Worker::~Worker() {
+  if (cleanup_work_item_)
+    main_thread_->PostTask(FROM_HERE,
+                           base::Bind(&WorkItem::OnDone, cleanup_work_item_));
+}
+
+void BackendImplV3::Worker::Cleanup(WorkItem* work_item) {
+  Trace("Worker::Cleanup");
+  if (!work_item->user_callback().is_null())
+    cleanup_work_item_ = work_item;
+
+  if (init_) {
+    IndexHeaderV3* index =
+      reinterpret_cast<IndexHeaderV3*>(index_header_->buffer());
+    index->crash = 0;
+  }
+
+  CloseFiles();
   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();
-  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();
-}
-
-base::FilePath BackendImpl::GetFileName(Addr address) const {
+
+  if (work_item->user_callback().is_null()) {
+    // This is the only message we don't return to the main thread, we are done
+    // with the work item for good.
+    work_item->Release();
+  }
+}
+
+void BackendImplV3::Worker::CloseFiles() {
+  index_header_ = NULL;
+  main_table_ = NULL;
+  extra_table_ = NULL;
+  index_backup_ = NULL;
+  block_files_->CloseFiles();
+  files_.clear();
+
+  big_index_header_ = NULL;
+  big_main_table_ = NULL;
+  big_extra_table_ = NULL;
+  big_extra_temp_table_ = NULL;
+  if (big_block_files_.get())
+    big_block_files_->CloseFiles();
+}
+
+File* BackendImplV3::Worker::GetExternalFile(Addr address, bool for_write) {
+  FilesMap::iterator it = files_.find(address.value());
+  if (it != files_.end())
+    return it->second;
+
+  scoped_refptr<disk_cache::File> file(new disk_cache::File(false));
+  if (for_write)
+    file->set_force_creation();
+  if (file->Init(GetFileName(address)))
+    files_[address.value()] = file.get();
+  else
+    file = NULL;
+
+  return file;
+}
+
+base::FilePath BackendImplV3::Worker::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);
 }
 
 // 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;
+bool BackendImplV3::Worker::CreateBackingStore(disk_cache::File* file) {
+  IndexHeaderV3 header;
+  memset(&header, 0, sizeof(header));
+  header.magic = kIndexMagicV3;
+  header.version = kVersion3;
+  header.max_block_file = kFirstAdditionalBlockFileV3;
+  
+  // Start with 12.5% of the size of the main table.
+  int extra_len = (user_flags_ & BASIC_UNIT_TEST) ? 8 : kBaseTableLen / 8;
+  header.table_len = kBaseTableLen + extra_len;
+  header.max_bucket = kBaseTableLen / 4 - 1;
+  header.flags = SMALL_CACHE;
 
   header.create_time = Time::Now().ToInternalValue();
+  header.base_time = (Time::Now() - TimeDelta::FromDays(20)).ToInternalValue();
 
   if (!file->Write(&header, sizeof(header), 0))
     return false;
 
-  return file->SetLength(GetIndexSize(header.table_len));
+  if (!file->SetLength(GetIndexBitmapSize(header.table_len)))
+    return false;
+
+  int flags = base::PLATFORM_FILE_READ |
+              base::PLATFORM_FILE_WRITE |
+              base::PLATFORM_FILE_CREATE |
+              base::PLATFORM_FILE_EXCLUSIVE_WRITE;
+
+  base::FilePath name = path_.AppendASCII(kIndexBackupName);
+  scoped_refptr<disk_cache::File> file2(new disk_cache::File(
+      base::CreatePlatformFile(name, flags, NULL, NULL)));
+
+  if (!file2->IsValid())
+    return false;
+
+  if (!file2->Write(&header, sizeof(header), 0))
+    return false;
+
+  if (!file2->SetLength(GetIndexBitmapSize(header.table_len)))
+    return false;
+
+  name = path_.AppendASCII(kTable1Name);
+  file2 = new disk_cache::File(base::CreatePlatformFile(name, flags, NULL,
+                                                        NULL));
+  if (!file2->IsValid())
+    return false;
+
+  if (!file2->SetLength(kBaseTableLen * kBytesPerCell))
+    return false;
+
+  name = path_.AppendASCII(kTable2Name);
+  file2 = new disk_cache::File(base::CreatePlatformFile(name, flags, NULL,
+                                                        NULL));
+  if (!file2->IsValid())
+    return false;
+
+  if (!file2->SetLength(extra_len * kBytesPerCell))
+    return false;
+
+  return true;
 }
 
-bool BackendImpl::InitBackingStore(bool* file_created) {
+bool BackendImplV3::Worker::CreateExtraTable(int extra_len) {
+  int flags = base::PLATFORM_FILE_READ |
+              base::PLATFORM_FILE_WRITE |
+              base::PLATFORM_FILE_CREATE |
+              base::PLATFORM_FILE_EXCLUSIVE_WRITE;
+
+  base::FilePath name = path_.AppendASCII(kTable2TempName);
+  scoped_refptr<disk_cache::File> file(new disk_cache::File(
+      base::CreatePlatformFile(name, flags, NULL, NULL)));
+  if (!file->IsValid())
+    return false;
+
+  if (!file->SetLength(extra_len * kBytesPerCell))
+    return false;
+
+  return true;
+}
+
+bool BackendImplV3::Worker::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());
+    ret = CreateBackingStore(file);
 
   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";
+  index_header_ = new MappedFile();
+  if (!index_header_->Init(index_name, 0)) {
+    LOG(ERROR) << "Unable to map index";
     return false;
   }
 
-  if (index_->GetLength() < sizeof(Index)) {
+  if (index_header_->GetLength() < sizeof(IndexBitmap)) {
     // We verify this again on CheckIndex() but it's easier to make sure now
     // that the header is there.
-    LOG(ERROR) << "Corrupt Index file";
+    LOG(ERROR) << "Corrupt index file";
+    return false;
+  }
+
+  main_table_ = new MappedFile();
+  if (!main_table_->Init(path_.AppendASCII(kTable1Name), 0)) {
+    LOG(ERROR) << "Unable to map index_tb1";
+    return false;
+  }
+
+  extra_table_ = new MappedFile();
+  if (!extra_table_->Init(path_.AppendASCII(kTable2Name), 0)) {
+    LOG(ERROR) << "Unable to map index_tb2";
+    return false;
+  }
+
+  index_backup_ = new MappedFile();
+  if (!index_backup_->Init(path_.AppendASCII(kIndexBackupName), 0)) {
+    LOG(ERROR) << "Unable to map index_bak";
     return false;
   }
 
   return true;
 }
 
-void BackendImpl::ReportError(int error) {
-  STRESS_DCHECK(!error || error == ERR_PREVIOUS_CRASH ||
-                error == ERR_CACHE_CREATED);
+bool BackendImplV3::Worker::LoadIndex(InitResult* init_result) {
+  init_result->index_data.index_bitmap =
+      reinterpret_cast<IndexBitmap*>(index_header_->buffer());
+  init_result->index_data.main_table =
+      reinterpret_cast<IndexBucket*>(main_table_->buffer());
+  init_result->index_data.extra_table =
+      reinterpret_cast<IndexBucket*>(extra_table_->buffer());
 
-  // We transmit positive numbers, instead of direct error codes.
-  DCHECK_LE(error, 0);
-  CACHE_UMA(CACHE_ERROR, "Error", 0, error * -1);
+  if (!CheckIndexFile(index_header_))
+    return false;
+
+  if (!CheckIndexFile(index_backup_))
+    return false;
+
+  IndexHeaderV3& header = init_result->index_data.index_bitmap->header;
+
+  size_t extra_table_len = header.table_len % kBaseTableLen;
+  size_t main_table_len = (kBaseTableLen - extra_table_len) * kBytesPerCell;
+  extra_table_len *= kBytesPerCell;
+
+  if (main_table_->GetLength() < main_table_len ||
+      extra_table_->GetLength() < extra_table_len) {
+    LOG(ERROR) << "Truncated table";
+    return false;
+  }
+
+  IndexBitmap* index = reinterpret_cast<IndexBitmap*>(index_backup_->buffer());
+
+  init_result->index_data.backup_header.reset(new IndexHeaderV3);
+  memcpy(init_result->index_data.backup_header.get(), &index->header,
+         sizeof(index->header));
+
+  size_t bitmap_len = GetIndexBitmapSize(index->header.table_len) -
+                      sizeof(index->header);
+  init_result->index_data.backup_bitmap.reset(new uint32[bitmap_len / 4]);
+  memcpy(init_result->index_data.backup_bitmap.get(), &index->bitmap,
+         bitmap_len);
+
+  // Close the backup.
+  index_backup_ = NULL;
+  return true;
 }
 
-
-bool BackendImpl::CheckIndex() {
-  DCHECK(data_);
-
-  size_t current_size = index_->GetLength();
-  if (current_size < sizeof(Index)) {
+bool BackendImplV3::Worker::CheckIndexFile(MappedFile* file) {
+  size_t current_size = file->GetLength();
+  if (current_size < sizeof(IndexBitmap)) {
     LOG(ERROR) << "Corrupt Index file";
     return false;
   }
 
-  if (new_eviction_) {
-    // We support versions 2.0 and 2.1, upgrading 2.0 to 2.1.
-    if (kIndexMagic != data_->header.magic ||
-        kCurrentVersion >> 16 != data_->header.version >> 16) {
-      LOG(ERROR) << "Invalid file version or magic";
-      return false;
-    }
-    if (kCurrentVersion == data_->header.version) {
-      // We need file version 2.1 for the new eviction algorithm.
-      UpgradeTo2_1();
-    }
-  } else {
-    if (kIndexMagic != data_->header.magic ||
-        kCurrentVersion != data_->header.version) {
-      LOG(ERROR) << "Invalid file version or magic";
-      return false;
-    }
+  IndexHeaderV3* header = reinterpret_cast<IndexHeaderV3*>(file->buffer());
+
+  if (kIndexMagicV3 != header->magic || kVersion3 != header->version) {
+    LOG(ERROR) << "Invalid file version or magic";
+    return false;
   }
 
-  if (!data_->header.table_len) {
+  if (header->table_len <= 0 || header->table_len > 1 << 22) {
     LOG(ERROR) << "Invalid table size";
     return false;
   }
 
-  if (current_size < GetIndexSize(data_->header.table_len) ||
-      data_->header.table_len & (kBaseTableLen - 1)) {
+  int min_mask = (user_flags_ & BASIC_UNIT_TEST) ? 0x3 : 0xff;
+  if (current_size < GetIndexBitmapSize(header->table_len) ||
+      header->table_len & (min_mask)) {
     LOG(ERROR) << "Corrupt Index file";
     return false;
   }
 
-  AdjustMaxCacheSize(data_->header.table_len);
+  //AdjustMaxCacheSize(header->table_len);
 
 #if !defined(NET_BUILD_STRESS_CACHE)
-  if (data_->header.num_bytes < 0 ||
-      (max_size_ < kint32max - kDefaultCacheSize &&
-       data_->header.num_bytes > max_size_ + kDefaultCacheSize)) {
-    LOG(ERROR) << "Invalid cache (current) size";
+  if (header->num_bytes < 0 || header->max_bytes < 0 ||
+      header->num_bytes > header->max_bytes + kDefaultCacheSize) {
+    LOG(ERROR) << "Invalid cache size";
     return false;
   }
 #endif
 
-  if (data_->header.num_entries < 0) {
+  if (header->num_entries < 0) {
     LOG(ERROR) << "Invalid number of entries";
     return false;
   }
 
-  if (!mask_)
-    mask_ = data_->header.table_len - 1;
-
   // Load the table into memory with a single read.
-  scoped_ptr<char[]> buf(new char[current_size]);
-  return index_->Read(buf.get(), current_size, 0);
+  //scoped_array<char> buf(new char[current_size]);
+  //return index_->Read(buf.get(), current_size, 0);
+  
+  return true;
 }
 
-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);
-  }
+bool BackendImplV3::Worker::InitStats(IndexHeaderV3* index,
+                                      InitResult* result) {
+  Addr address(index->stats);
+  if (!address.is_initialized())
+    return true;
 
   if (!address.is_block_file()) {
     NOTREACHED();
     return false;
   }
 
+  int size = address.num_blocks() * address.BlockSize();
+
   // Load the required data.
-  size = address.num_blocks() * address.BlockSize();
-  MappedFile* file = File(address);
+  MappedFile* file = GetMappedFile(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();
+  result->stats_data = data.Pass();
   return true;
 }
 
+int BackendImplV3::Worker::GrowDone() {
+  Trace("Worker::GrowDone");
+  if (!init_)
+    return ERR_OPERATION_FAILED;
+
+  DCHECK(doubling_index_);
+  doubling_index_ = false;
+
+  extra_table_ = big_extra_temp_table_;
+  big_extra_temp_table_ = NULL;
+
+  return ERR_NO_ERROR;
+}
+
 }  // namespace disk_cache