Disk cache v3 ref2

net/disk_cache/v3/entry_impl_v3.cc

Index: net/disk_cache/v3/entry_impl_v3.cc
===================================================================
--- net/disk_cache/v3/entry_impl_v3.cc	(revision 232523)
+++ net/disk_cache/v3/entry_impl_v3.cc	(working copy)
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "net/disk_cache/entry_impl.h"
+#include "net/disk_cache/v3/entry_impl_v3.h"
 
 #include "base/hash.h"
 #include "base/message_loop/message_loop.h"
@@ -10,12 +10,14 @@
 #include "base/strings/string_util.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
-#include "net/disk_cache/backend_impl.h"
 #include "net/disk_cache/bitmap.h"
 #include "net/disk_cache/cache_util.h"
 #include "net/disk_cache/histogram_macros.h"
 #include "net/disk_cache/net_log_parameters.h"
-#include "net/disk_cache/sparse_control.h"
+#include "net/disk_cache/storage_block-inl.h"
+#include "net/disk_cache/v3/backend_impl_v3.h"
+#include "net/disk_cache/v3/disk_format_v3.h"
+#include "net/disk_cache/v3/sparse_control_v3.h"
 
 using base::Time;
 using base::TimeDelta;
@@ -23,26 +25,35 @@
 
 namespace {
 
+const int kMinBufferSize = disk_cache::kMaxBlockSize;
 const int kMaxBufferSize = 1024 * 1024;  // 1 MB.
+const int kKeyIndex = 0;
 
 }  // namespace
 
 namespace disk_cache {
 
+typedef StorageBlock<EntryRecord> CacheEntryBlockV3;
+typedef StorageBlock<ShortEntryRecord> CacheShortEntryBlock;
+
 // This class handles individual memory buffers that store data before it is
 // sent to disk. The buffer can start at any offset, but if we try to write to
-// anywhere in the first 16KB of the file (kMaxBlockSize), we set the offset to
+// anywhere in the first 16KB of the file (kMaxBlockSize), we set the offset to jaja
 // zero. The buffer grows up to a size determined by the backend, to keep the
 // total memory used under control.
-class EntryImpl::UserBuffer {
+class EntryImplV3::UserBuffer {
  public:
-  explicit UserBuffer(BackendImpl* backend)
-      : backend_(backend->GetWeakPtr()), offset_(0), grow_allowed_(true) {
-    buffer_.reserve(kMaxBlockSize);
+  explicit UserBuffer(BackendImplV3* backend)
+      : backend_(backend->GetWeakPtr()),
+        offset_(0),
+        grow_allowed_(true),
+        force_size_(false) {
+    buffer_ = new net::GrowableIOBuffer();
+    buffer_->SetCapacity(kMinBufferSize);
   }
   ~UserBuffer() {
     if (backend_)
-      backend_->BufferDeleted(capacity() - kMaxBlockSize);
+      backend_->BufferDeleted(capacity() - kMinBufferSize);
   }
 
   // Returns true if we can handle writing |len| bytes to |offset|.
@@ -63,26 +74,28 @@
   // Read |len| bytes from |buf| at the given |offset|.
   int Read(int offset, IOBuffer* buf, int len);
 
-  // Prepare this buffer for reuse.
-  void Reset();
+  void Rebase();
 
-  char* Data() { return buffer_.size() ? &buffer_[0] : NULL; }
-  int Size() { return static_cast<int>(buffer_.size()); }
+  void ForceSize(bool value);
+
+  net::IOBuffer* Get();
+  int Size() { return static_cast<int>(buffer_->offset()); }
   int Start() { return offset_; }
   int End() { return offset_ + Size(); }
 
  private:
-  int capacity() { return static_cast<int>(buffer_.capacity()); }
+  int capacity() { return buffer_->capacity(); }
   bool GrowBuffer(int required, int limit);
 
-  base::WeakPtr<BackendImpl> backend_;
+  base::WeakPtr<BackendImplV3> backend_;
   int offset_;
-  std::vector<char> buffer_;
+  scoped_refptr<net::GrowableIOBuffer> buffer_;
   bool grow_allowed_;
+  bool force_size_;
   DISALLOW_COPY_AND_ASSIGN(UserBuffer);
 };
 
-bool EntryImpl::UserBuffer::PreWrite(int offset, int len) {
+bool EntryImplV3::UserBuffer::PreWrite(int offset, int len) {
   DCHECK_GE(offset, 0);
   DCHECK_GE(len, 0);
   DCHECK_GE(offset + len, 0);
@@ -95,39 +108,39 @@
   if (offset + len <= capacity())
     return true;
 
-  // If we are writing to the first 16K (kMaxBlockSize), we want to keep the
-  // buffer offset_ at 0.
-  if (!Size() && offset > kMaxBlockSize)
+  if (!Size())
     return GrowBuffer(len, kMaxBufferSize);
 
   int required = offset - offset_ + len;
   return GrowBuffer(required, kMaxBufferSize * 6 / 5);
 }
 
-void EntryImpl::UserBuffer::Truncate(int offset) {
+void EntryImplV3::UserBuffer::Truncate(int offset) {
   DCHECK_GE(offset, 0);
   DCHECK_GE(offset, offset_);
   DVLOG(3) << "Buffer truncate at " << offset << " current " << offset_;
 
   offset -= offset_;
   if (Size() >= offset)
-    buffer_.resize(offset);
+    buffer_->set_offset(offset);
 }
 
-void EntryImpl::UserBuffer::Write(int offset, IOBuffer* buf, int len) {
+void EntryImplV3::UserBuffer::Write(int offset, IOBuffer* buf, int len) {
   DCHECK_GE(offset, 0);
   DCHECK_GE(len, 0);
   DCHECK_GE(offset + len, 0);
   DCHECK_GE(offset, offset_);
   DVLOG(3) << "Buffer write at " << offset << " current " << offset_;
 
-  if (!Size() && offset > kMaxBlockSize)
+  if (!Size())
     offset_ = offset;
 
   offset -= offset_;
 
-  if (offset > Size())
-    buffer_.resize(offset);
+  if (offset > Size()) {
+    memset(buffer_->data(), 0, offset - Size());
+    buffer_->set_offset(offset);
+  }
 
   if (!len)
     return;
@@ -136,17 +149,18 @@
   int valid_len = Size() - offset;
   int copy_len = std::min(valid_len, len);
   if (copy_len) {
-    memcpy(&buffer_[offset], buffer, copy_len);
+    memcpy(buffer_->StartOfBuffer() + offset, buffer, copy_len);
     len -= copy_len;
     buffer += copy_len;
   }
   if (!len)
     return;
 
-  buffer_.insert(buffer_.end(), buffer, buffer + len);
+  memcpy(buffer_->data(), buffer, len);
+  buffer_->set_offset(buffer_->offset() + len);
 }
 
-bool EntryImpl::UserBuffer::PreRead(int eof, int offset, int* len) {
+bool EntryImplV3::UserBuffer::PreRead(int eof, int offset, int* len) {
   DCHECK_GE(offset, 0);
   DCHECK_GT(*len, 0);
 
@@ -171,7 +185,7 @@
   return (offset - offset_ < Size());
 }
 
-int EntryImpl::UserBuffer::Read(int offset, IOBuffer* buf, int len) {
+int EntryImplV3::UserBuffer::Read(int offset, IOBuffer* buf, int len) {
   DCHECK_GE(offset, 0);
   DCHECK_GT(len, 0);
   DCHECK(Size() || offset < offset_);
@@ -192,24 +206,28 @@
   DCHECK_GE(start, 0);
   DCHECK_GE(available, 0);
   len = std::min(len, available);
-  memcpy(buf->data() + clean_bytes, &buffer_[start], len);
+  memcpy(buf->data() + clean_bytes, buffer_->StartOfBuffer() + start, len);
   return len + clean_bytes;
 }
 
-void EntryImpl::UserBuffer::Reset() {
-  if (!grow_allowed_) {
-    if (backend_)
-      backend_->BufferDeleted(capacity() - kMaxBlockSize);
-    grow_allowed_ = true;
-    std::vector<char> tmp;
-    buffer_.swap(tmp);
-    buffer_.reserve(kMaxBlockSize);
-  }
+void EntryImplV3::UserBuffer::Rebase() {
+  DCHECK(!Size());
+  DCHECK(offset_ < capacity());
+  memset(buffer_->data(), 0, offset_);
+  buffer_->set_offset(offset_);
   offset_ = 0;
-  buffer_.clear();
 }
 
-bool EntryImpl::UserBuffer::GrowBuffer(int required, int limit) {
+void EntryImplV3::UserBuffer::ForceSize(bool value) {
+  force_size_ = value;
+}
+
+net::IOBuffer* EntryImplV3::UserBuffer::Get() {
+  buffer_->set_offset(0);
+  return buffer_.get();
+}
+
+bool EntryImplV3::UserBuffer::GrowBuffer(int required, int limit) {
   DCHECK_GE(required, 0);
   int current_size = capacity();
   if (required <= current_size)
@@ -221,169 +239,183 @@
   if (!backend_)
     return false;
 
-  int to_add = std::max(required - current_size, kMaxBlockSize * 4);
+  int to_add = std::max(required - current_size, kMinBufferSize * 4);
   to_add = std::max(current_size, to_add);
   required = std::min(current_size + to_add, limit);
 
-  grow_allowed_ = backend_->IsAllocAllowed(current_size, required);
+  grow_allowed_ = backend_->IsAllocAllowed(current_size, required, force_size_);
+  force_size_ = false;
   if (!grow_allowed_)
     return false;
 
   DVLOG(3) << "Buffer grow to " << required;
 
-  buffer_.reserve(required);
+  buffer_->SetCapacity(required);
   return true;
 }
 
 // ------------------------------------------------------------------------
 
-EntryImpl::EntryImpl(BackendImpl* backend, Addr address, bool read_only)
-    : entry_(NULL, Addr(0)), node_(NULL, Addr(0)),
-      backend_(backend->GetWeakPtr()), doomed_(false), read_only_(read_only),
-      dirty_(false) {
-  entry_.LazyInit(backend->File(address), address);
+EntryImplV3::EntryImplV3(BackendImplV3* backend, Addr address, bool read_only)
+    : backend_(backend->GetWeakPtr()),
+      address_(address),
+      num_handles_(0),
+      doomed_(false),
+      read_only_(read_only),
+      dirty_(true),
+      modified_(false),
+      callback_(base::Bind(&EntryImplV3::OnIOComplete,
+                           base::Unretained(this))) {
   for (int i = 0; i < kNumStreams; i++) {
     unreported_size_[i] = 0;
   }
 }
 
-bool EntryImpl::CreateEntry(Addr node_address, const std::string& key,
-                            uint32 hash) {
-  Trace("Create entry In");
-  EntryStore* entry_store = entry_.Data();
-  RankingsNode* node = node_.Data();
-  memset(entry_store, 0, sizeof(EntryStore) * entry_.address().num_blocks());
-  memset(node, 0, sizeof(RankingsNode));
-  if (!node_.LazyInit(backend_->File(node_address), node_address))
-    return false;
+EntryImplV3::EntryImplV3(BackendImplV3* backend,
+                         Addr address,
+                         const std::string& key,
+                         scoped_ptr<EntryRecord> record)
+    : entry_(record.Pass()),
+      backend_(backend->GetWeakPtr()),
+      key_(key),
+      address_(address),
+      num_handles_(0),
+      doomed_(false),
+      read_only_(false),
+      dirty_(false),
+      modified_(false),
+      callback_(base::Bind(&EntryImplV3::OnIOComplete,
+                           base::Unretained(this))) {
+  for (int i = 0; i < kNumStreams; i++) {
+    unreported_size_[i] = 0;
+  }
+}
 
-  entry_store->rankings_node = node_address.value();
-  node->contents = entry_.address().value();
+EntryImplV3::EntryImplV3(BackendImplV3* backend,
+                         Addr address,
+                         const std::string& key,
+                         scoped_ptr<ShortEntryRecord> record)
+    : short_entry_(record.Pass()),
+      backend_(backend->GetWeakPtr()),
+      key_(key),
+      address_(address),
+      num_handles_(0),
+      doomed_(false),
+      read_only_(false),
+      dirty_(false),
+      modified_(false),
+      callback_(base::Bind(&EntryImplV3::OnIOComplete,
+                           base::Unretained(this))) {
+  for (int i = 0; i < kNumStreams; i++) {
+    unreported_size_[i] = 0;
+  }
+}
 
-  entry_store->hash = hash;
-  entry_store->creation_time = Time::Now().ToInternalValue();
-  entry_store->key_len = static_cast<int32>(key.size());
-  if (entry_store->key_len > kMaxInternalKeyLength) {
-    Addr address(0);
-    if (!CreateBlock(entry_store->key_len + 1, &address))
-      return false;
+void EntryImplV3::CreateEntry(const std::string& key, uint32 hash,
+                              ShortEntryRecord* old_info) {
+  Trace("Create entry In");
 
-    entry_store->long_key = address.value();
-    File* key_file = GetBackingFile(address, kKeyFileIndex);
-    key_ = key;
+  key_ = key;
+  entry_.reset(new EntryRecord);
+  memset(entry_.get(), 0, sizeof(*entry_.get()));
+  entry_->key_len = static_cast<int>(key.size());
+  entry_->hash = hash;
+  entry_->creation_time = backend_->GetCurrentTime().ToInternalValue();
+  entry_->last_access_time = entry_->creation_time;
+  entry_->last_modified_time = entry_->creation_time;
+  dirty_ = true;
+  backend_->UpdateRank(this, true);
 
-    size_t offset = 0;
-    if (address.is_block_file())
-      offset = address.start_block() * address.BlockSize() + kBlockHeaderSize;
+  if (old_info) {
+    entry_->reuse_count = old_info->reuse_count;
+    entry_->refetch_count = old_info->refetch_count;
+  }
 
-    if (!key_file || !key_file->Write(key.data(), key.size(), offset)) {
-      DeleteData(address, kKeyFileIndex);
-      return false;
-    }
-
-    if (address.is_separate_file())
-      key_file->SetLength(key.size() + 1);
-  } else {
-    memcpy(entry_store->key, key.data(), key.size());
-    entry_store->key[key.size()] = '\0';
-  }
   backend_->ModifyStorageSize(0, static_cast<int32>(key.size()));
   CACHE_UMA(COUNTS, "KeySize", 0, static_cast<int32>(key.size()));
-  node->dirty = backend_->GetCurrentEntryId();
+
+  WriteKey();
+  num_handles_++;
   Log("Create Entry ");
-  return true;
 }
 
-uint32 EntryImpl::GetHash() {
-  return entry_.Data()->hash;
+void EntryImplV3::OnOpenEntry() {
+  num_handles_++;
 }
 
-bool EntryImpl::IsSameEntry(const std::string& key, uint32 hash) {
-  if (entry_.Data()->hash != hash ||
-      static_cast<size_t>(entry_.Data()->key_len) != key.size())
-    return false;
+scoped_ptr<ShortEntryRecord> EntryImplV3::GetShortEntryRecord() {
+  return short_entry_.Pass();
+}
 
-  return (key.compare(GetKey()) == 0);
+uint32 EntryImplV3::GetHash() const {
+  return entry_->hash;
 }
 
-void EntryImpl::InternalDoom() {
-  net_log_.AddEvent(net::NetLog::TYPE_ENTRY_DOOM);
-  DCHECK(node_.HasData());
-  if (!node_.Data()->dirty) {
-    node_.Data()->dirty = backend_->GetCurrentEntryId();
-    node_.Store();
-  }
-  doomed_ = true;
+Addr EntryImplV3::GetAddress() const {
+  return address_;
 }
 
-// This only includes checks that relate to the first block of the entry (the
-// first 256 bytes), and values that should be set from the entry creation.
-// Basically, even if there is something wrong with this entry, we want to see
-// if it is possible to load the rankings node and delete them together.
-bool EntryImpl::SanityCheck() {
-  if (!entry_.VerifyHash())
-    return false;
+int EntryImplV3::GetReuseCounter() const {
+  return entry_->reuse_count;
+}
 
-  EntryStore* stored = entry_.Data();
-  if (!stored->rankings_node || stored->key_len <= 0)
-    return false;
+void EntryImplV3::SetReuseCounter(int counter) {
+  DCHECK_LT(counter, 256);
+  DCHECK_GE(counter, 0);
+  entry_->reuse_count = static_cast<uint8>(counter);
+  dirty_ = true;
+}
 
-  if (stored->reuse_count < 0 || stored->refetch_count < 0)
-    return false;
+int EntryImplV3::GetRefetchCounter() const {
+  return entry_->refetch_count;
+}
 
-  Addr rankings_addr(stored->rankings_node);
-  if (!rankings_addr.SanityCheckForRankings())
-    return false;
+void EntryImplV3::SetRefetchCounter(int counter) {
+  DCHECK_LT(counter, 256);
+  DCHECK_GE(counter, 0);
+  entry_->refetch_count = static_cast<uint8>(counter);
+  dirty_ = true;
+}
 
-  Addr next_addr(stored->next);
-  if (next_addr.is_initialized() && !next_addr.SanityCheckForEntry()) {
-    STRESS_NOTREACHED();
+bool EntryImplV3::IsSameEntry(const std::string& key, uint32 hash) {
+  if (entry_->hash != hash ||
+      static_cast<size_t>(entry_->key_len) != key.size())
     return false;
-  }
-  STRESS_DCHECK(next_addr.value() != entry_.address().value());
 
-  if (stored->state > ENTRY_DOOMED || stored->state < ENTRY_NORMAL)
-    return false;
+  return (key.compare(GetKey()) == 0);
+}
 
-  Addr key_addr(stored->long_key);
-  if ((stored->key_len <= kMaxInternalKeyLength && key_addr.is_initialized()) ||
-      (stored->key_len > kMaxInternalKeyLength && !key_addr.is_initialized()))
-    return false;
+void EntryImplV3::InternalDoom() {
+  DCHECK(!doomed_);
+  net_log_.AddEvent(net::NetLog::TYPE_ENTRY_DOOM);
+  doomed_ = true;
+  dirty_ = true;
+}
 
-  if (!key_addr.SanityCheck())
-    return false;
+bool EntryImplV3::SanityCheck() {
+  DCHECK(BasicSanityCheck(*entry_.get()));
 
-  if (key_addr.is_initialized() &&
-      ((stored->key_len < kMaxBlockSize && key_addr.is_separate_file()) ||
-       (stored->key_len >= kMaxBlockSize && key_addr.is_block_file())))
+  if (entry_->reuse_count < 0 || entry_->refetch_count < 0)
     return false;
 
-  int num_blocks = NumBlocksForEntry(stored->key_len);
-  if (entry_.address().num_blocks() != num_blocks)
+  if (entry_->state > ENTRY_USED || entry_->state < ENTRY_NEW)
     return false;
 
   return true;
 }
 
-bool EntryImpl::DataSanityCheck() {
-  EntryStore* stored = entry_.Data();
-  Addr key_addr(stored->long_key);
-
-  // The key must be NULL terminated.
-  if (!key_addr.is_initialized() && stored->key[stored->key_len])
+bool EntryImplV3::DataSanityCheck() {
+  if (entry_->hash != base::Hash(GetKey()))
     return false;
 
-  if (stored->hash != base::Hash(GetKey()))
-    return false;
-
   for (int i = 0; i < kNumStreams; i++) {
-    Addr data_addr(stored->data_addr[i]);
-    int data_size = stored->data_size[i];
+    Addr data_addr(entry_->data_addr[i]);
+    int data_size = entry_->data_size[i];
     if (data_size < 0)
       return false;
     if (!data_size && data_addr.is_initialized())
       return false;
-    if (!data_addr.SanityCheck())
+    if (!data_addr.SanityCheckV3())
       return false;
     if (!data_size)
       continue;
@@ -395,40 +427,76 @@
   return true;
 }
 
-void EntryImpl::FixForDelete() {
-  EntryStore* stored = entry_.Data();
-  Addr key_addr(stored->long_key);
+// Static.
+bool EntryImplV3::BasicSanityCheck(const EntryRecord& record) {
+  CacheEntryBlockV3 entry_block;
+  entry_block.SetData(const_cast<EntryRecord*>(&record));
+  if (!entry_block.VerifyHash())
+    return false;
 
-  if (!key_addr.is_initialized())
-    stored->key[stored->key_len] = '\0';
+  if (record.key_len <= 0 || record.data_size[0] < record.key_len)
+    return false;
 
-  for (int i = 0; i < kNumStreams; i++) {
-    Addr data_addr(stored->data_addr[i]);
-    int data_size = stored->data_size[i];
-    if (data_addr.is_initialized()) {
-      if ((data_size <= kMaxBlockSize && data_addr.is_separate_file()) ||
-          (data_size > kMaxBlockSize && data_addr.is_block_file()) ||
-          !data_addr.SanityCheck()) {
-        STRESS_NOTREACHED();
-        // The address is weird so don't attempt to delete it.
-        stored->data_addr[i] = 0;
-        // In general, trust the stored size as it should be in sync with the
-        // total size tracked by the backend.
-      }
-    }
-    if (data_size < 0)
-      stored->data_size[i] = 0;
-  }
-  entry_.Store();
+  Addr data_addr(record.data_addr[0]);
+  if (!data_addr.is_initialized() || !data_addr.SanityCheckV3())
+    return false;
+
+  if (record.data_size[0] <= kMaxBlockSize && data_addr.is_separate_file())
+    return false;
+
+  if (record.data_size[0] > kMaxBlockSize && data_addr.is_block_file())
+    return false;
+
+  return true;
 }
 
-void EntryImpl::SetTimes(base::Time last_used, base::Time last_modified) {
-  node_.Data()->last_used = last_used.ToInternalValue();
-  node_.Data()->last_modified = last_modified.ToInternalValue();
-  node_.set_modified();
+// Static.
+bool EntryImplV3::DeletedSanityCheck(const ShortEntryRecord& record) {
+  CacheShortEntryBlock entry_block;
+  entry_block.SetData(const_cast<ShortEntryRecord*>(&record));
+  if (!entry_block.VerifyHash())
+    return false;
+
+  if (record.key_len <= 0)
+    return false;
+
+  return true;
 }
 
-void EntryImpl::BeginLogging(net::NetLog* net_log, bool created) {
+void EntryImplV3::FixForDelete() {
+  //EntryStore* stored = entry_.Data();
+  //Addr key_addr(stored->long_key);
+
+  //if (!key_addr.is_initialized())
+  //  stored->key[stored->key_len] = '\0';
+
+  //for (int i = 0; i < kNumStreams; i++) {
+  //  Addr data_addr(stored->data_addr[i]);
+  //  int data_size = stored->data_size[i];
+  //  if (data_addr.is_initialized()) {
+  //    if ((data_size <= kMaxBlockSize && data_addr.is_separate_file()) ||
+  //        (data_size > kMaxBlockSize && data_addr.is_block_file()) ||
+  //        !data_addr.SanityCheck()) {
+  //      STRESS_NOTREACHED();
+  //      // The address is weird so don't attempt to delete it.
+  //      stored->data_addr[i] = 0;
+  //      // In general, trust the stored size as it should be in sync with the
+  //      // total size tracked by the backend.
+  //    }
+  //  }
+  //  if (data_size < 0)
+  //    stored->data_size[i] = 0;
+  //}
+  //entry_.Store();
+}
+
+void EntryImplV3::SetTimes(base::Time last_used, base::Time last_modified) {
+  entry_->last_access_time = last_used.ToInternalValue();
+  entry_->last_modified_time = last_modified.ToInternalValue();
+  dirty_ = true;
+}
+
+void EntryImplV3::BeginLogging(net::NetLog* net_log, bool created) {
   DCHECK(!net_log_.net_log());
   net_log_ = net::BoundNetLog::Make(
       net_log, net::NetLog::SOURCE_DISK_CACHE_ENTRY);
@@ -437,112 +505,92 @@
       CreateNetLogEntryCreationCallback(this, created));
 }
 
-const net::BoundNetLog& EntryImpl::net_log() const {
+const net::BoundNetLog& EntryImplV3::net_log() const {
   return net_log_;
 }
 
+void EntryImplV3::NotifyDestructionForTest(const CompletionCallback& callback) {
+  DCHECK(destruction_callback_.is_null());
+  destruction_callback_ = callback;
+}
+
 // ------------------------------------------------------------------------
 
-void EntryImpl::Doom() {
-  if (background_queue_)
-    background_queue_->DoomEntryImpl(this);
-}
-
-void EntryImpl::DoomImpl() {
+void EntryImplV3::Doom() {
   if (doomed_ || !backend_)
     return;
 
-  SetPointerForInvalidEntry(backend_->GetCurrentEntryId());
   backend_->InternalDoomEntry(this);
 }
 
-void EntryImpl::Close() {
-  if (background_queue_)
-    background_queue_->CloseEntryImpl(this);
+void EntryImplV3::Close() {
+  num_handles_--;
+  if (!num_handles_) {
+    if (sparse_.get())
+      sparse_->Close();
+
+    if (!pending_operations_.empty()) {
+      PendingOperation op =
+          { PENDING_CLEANUP, 0, 0, NULL, 0, CompletionCallback(), false };
+      pending_operations_.push(op);
+    } else {
+      Cleanup();
+    }
+  }
+  Release();
 }
 
-std::string EntryImpl::GetKey() const {
-  CacheEntryBlock* entry = const_cast<CacheEntryBlock*>(&entry_);
-  int key_len = entry->Data()->key_len;
-  if (key_len <= kMaxInternalKeyLength)
-    return std::string(entry->Data()->key);
-
-  // We keep a copy of the key so that we can always return it, even if the
-  // backend is disabled.
-  if (!key_.empty())
-    return key_;
-
-  Addr address(entry->Data()->long_key);
-  DCHECK(address.is_initialized());
-  size_t offset = 0;
-  if (address.is_block_file())
-    offset = address.start_block() * address.BlockSize() + kBlockHeaderSize;
-
-  COMPILE_ASSERT(kNumStreams == kKeyFileIndex, invalid_key_index);
-  File* key_file = const_cast<EntryImpl*>(this)->GetBackingFile(address,
-                                                                kKeyFileIndex);
-  if (!key_file)
-    return std::string();
-
-  ++key_len;  // We store a trailing \0 on disk that we read back below.
-  if (!offset && key_file->GetLength() != static_cast<size_t>(key_len))
-    return std::string();
-
-  if (!key_file->Read(WriteInto(&key_, key_len), key_len, offset))
-    key_.clear();
+std::string EntryImplV3::GetKey() const {
   return key_;
 }
 
-Time EntryImpl::GetLastUsed() const {
-  CacheRankingsBlock* node = const_cast<CacheRankingsBlock*>(&node_);
-  return Time::FromInternalValue(node->Data()->last_used);
+Time EntryImplV3::GetLastUsed() const {
+  return Time::FromInternalValue(entry_->last_access_time);
 }
 
-Time EntryImpl::GetLastModified() const {
-  CacheRankingsBlock* node = const_cast<CacheRankingsBlock*>(&node_);
-  return Time::FromInternalValue(node->Data()->last_modified);
+Time EntryImplV3::GetLastModified() const {
+  return Time::FromInternalValue(entry_->last_modified_time);
 }
 
-int32 EntryImpl::GetDataSize(int index) const {
+int32 EntryImplV3::GetDataSize(int index) const {
   if (index < 0 || index >= kNumStreams)
     return 0;
 
-  CacheEntryBlock* entry = const_cast<CacheEntryBlock*>(&entry_);
-  return entry->Data()->data_size[index];
+  return GetAdjustedSize(index, entry_->data_size[index]);
 }
 
-int EntryImpl::ReadData(int index, int offset, IOBuffer* buf, int buf_len,
+int32 EntryImplV3::GetAdjustedSize(int index, int real_size) const {
+  DCHECK_GE(index, 0);
+  DCHECK_LE(index, kNumStreams);
+
+  if (index == kKeyIndex)
+    return real_size - key_.size();
+
+  return real_size;
+}
+
+int EntryImplV3::ReadData(int index, int offset, IOBuffer* buf, int buf_len,
                         const CompletionCallback& callback) {
-  if (callback.is_null())
-    return ReadDataImpl(index, offset, buf, buf_len, callback);
-
-  DCHECK(node_.Data()->dirty || read_only_);
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
 
-  int entry_size = entry_.Data()->data_size[index];
-  if (offset >= entry_size || offset < 0 || !buf_len)
-    return 0;
-
   if (buf_len < 0)
     return net::ERR_INVALID_ARGUMENT;
 
-  if (!background_queue_)
-    return net::ERR_UNEXPECTED;
-
-  background_queue_->ReadData(this, index, offset, buf, buf_len, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int EntryImpl::ReadDataImpl(int index, int offset, IOBuffer* buf, int buf_len,
-                            const CompletionCallback& callback) {
+  if (!pending_operations_.empty()) {
+    PendingOperation op =
+        { PENDING_READ, index, offset, buf, buf_len, callback, false };
+    pending_operations_.push(op);
+    return net::ERR_IO_PENDING;
+  }
+  
   if (net_log_.IsLoggingAllEvents()) {
     net_log_.BeginEvent(
         net::NetLog::TYPE_ENTRY_READ_DATA,
         CreateNetLogReadWriteDataCallback(index, offset, buf_len, false));
   }
 
-  int result = InternalReadData(index, offset, buf, buf_len, callback);
+  int result = ReadDataImpl(index, offset, buf, buf_len, NULL, callback);
 
   if (result != net::ERR_IO_PENDING && net_log_.IsLoggingAllEvents()) {
     net_log_.EndEvent(
@@ -552,37 +600,29 @@
   return result;
 }
 
-int EntryImpl::WriteData(int index, int offset, IOBuffer* buf, int buf_len,
+int EntryImplV3::WriteData(int index, int offset, IOBuffer* buf, int buf_len,
                          const CompletionCallback& callback, bool truncate) {
-  if (callback.is_null())
-    return WriteDataImpl(index, offset, buf, buf_len, callback, truncate);
-
-  DCHECK(node_.Data()->dirty || read_only_);
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
 
   if (offset < 0 || buf_len < 0)
     return net::ERR_INVALID_ARGUMENT;
 
-  if (!background_queue_)
-    return net::ERR_UNEXPECTED;
+  if (!pending_operations_.empty()) {
+    PendingOperation op =
+        { PENDING_WRITE, index, offset, buf, buf_len, callback, truncate };
+    pending_operations_.push(op);
+    return net::ERR_IO_PENDING;
+  }
 
-  background_queue_->WriteData(this, index, offset, buf, buf_len, truncate,
-                               callback);
-  return net::ERR_IO_PENDING;
-}
-
-int EntryImpl::WriteDataImpl(int index, int offset, IOBuffer* buf, int buf_len,
-                             const CompletionCallback& callback,
-                             bool truncate) {
   if (net_log_.IsLoggingAllEvents()) {
     net_log_.BeginEvent(
         net::NetLog::TYPE_ENTRY_WRITE_DATA,
         CreateNetLogReadWriteDataCallback(index, offset, buf_len, truncate));
   }
 
-  int result = InternalWriteData(index, offset, buf, buf_len, callback,
-                                 truncate);
+  int result = WriteDataImpl(index, offset, buf, buf_len, NULL, callback,
+                             truncate);
 
   if (result != net::ERR_IO_PENDING && net_log_.IsLoggingAllEvents()) {
     net_log_.EndEvent(
@@ -592,109 +632,58 @@
   return result;
 }
 
-int EntryImpl::ReadSparseData(int64 offset, IOBuffer* buf, int buf_len,
+int EntryImplV3::ReadSparseData(int64 offset, IOBuffer* buf, int buf_len,
                               const CompletionCallback& callback) {
-  if (callback.is_null())
-    return ReadSparseDataImpl(offset, buf, buf_len, callback);
+  if (!sparse_.get())
+     sparse_.reset(new SparseControlV3(this));
 
-  if (!background_queue_)
-    return net::ERR_UNEXPECTED;
-
-  background_queue_->ReadSparseData(this, offset, buf, buf_len, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int EntryImpl::ReadSparseDataImpl(int64 offset, IOBuffer* buf, int buf_len,
-                                  const CompletionCallback& callback) {
-  DCHECK(node_.Data()->dirty || read_only_);
-  int result = InitSparseData();
-  if (net::OK != result)
-    return result;
-
   TimeTicks start = TimeTicks::Now();
-  result = sparse_->StartIO(SparseControl::kReadOperation, offset, buf, buf_len,
-                            callback);
+  int result = sparse_->StartIO(SparseControlV3::kReadOperation, offset, buf,
+                                buf_len, callback);
   ReportIOTime(kSparseRead, start);
   return result;
 }
 
-int EntryImpl::WriteSparseData(int64 offset, IOBuffer* buf, int buf_len,
+int EntryImplV3::WriteSparseData(int64 offset, IOBuffer* buf, int buf_len,
                                const CompletionCallback& callback) {
-  if (callback.is_null())
-    return WriteSparseDataImpl(offset, buf, buf_len, callback);
+  if (!sparse_.get())
+     sparse_.reset(new SparseControlV3(this));
 
-  if (!background_queue_)
-    return net::ERR_UNEXPECTED;
-
-  background_queue_->WriteSparseData(this, offset, buf, buf_len, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int EntryImpl::WriteSparseDataImpl(int64 offset, IOBuffer* buf, int buf_len,
-                                   const CompletionCallback& callback) {
-  DCHECK(node_.Data()->dirty || read_only_);
-  int result = InitSparseData();
-  if (net::OK != result)
-    return result;
-
   TimeTicks start = TimeTicks::Now();
-  result = sparse_->StartIO(SparseControl::kWriteOperation, offset, buf,
-                            buf_len, callback);
+  int result = sparse_->StartIO(SparseControlV3::kWriteOperation, offset, buf,
+                                buf_len, callback);
   ReportIOTime(kSparseWrite, start);
   return result;
 }
 
-int EntryImpl::GetAvailableRange(int64 offset, int len, int64* start,
+int EntryImplV3::GetAvailableRange(int64 offset, int len, int64* start,
                                  const CompletionCallback& callback) {
-  if (!background_queue_)
-    return net::ERR_UNEXPECTED;
+  if (!sparse_.get())
+     sparse_.reset(new SparseControlV3(this));
 
-  background_queue_->GetAvailableRange(this, offset, len, start, callback);
-  return net::ERR_IO_PENDING;
+  return sparse_->GetAvailableRange(offset, len, start, callback);
 }
 
-int EntryImpl::GetAvailableRangeImpl(int64 offset, int len, int64* start) {
-  int result = InitSparseData();
-  if (net::OK != result)
-    return result;
-
-  return sparse_->GetAvailableRange(offset, len, start);
-}
-
-bool EntryImpl::CouldBeSparse() const {
+bool EntryImplV3::CouldBeSparse() const {
   if (sparse_.get())
-    return true;
+    return sparse_->CouldBeSparse();
 
-  scoped_ptr<SparseControl> sparse;
-  sparse.reset(new SparseControl(const_cast<EntryImpl*>(this)));
+  scoped_ptr<SparseControlV3> sparse;
+  sparse.reset(new SparseControlV3(const_cast<EntryImplV3*>(this)));
   return sparse->CouldBeSparse();
 }
 
-void EntryImpl::CancelSparseIO() {
-  if (background_queue_)
-    background_queue_->CancelSparseIO(this);
-}
-
-void EntryImpl::CancelSparseIOImpl() {
+void EntryImplV3::CancelSparseIO() {
   if (!sparse_.get())
     return;
 
   sparse_->CancelIO();
 }
 
-int EntryImpl::ReadyForSparseIO(const CompletionCallback& callback) {
+int EntryImplV3::ReadyForSparseIO(const CompletionCallback& callback) {
   if (!sparse_.get())
     return net::OK;
 
-  if (!background_queue_)
-    return net::ERR_UNEXPECTED;
-
-  background_queue_->ReadyForSparseIO(this, callback);
-  return net::ERR_IO_PENDING;
-}
-
-int EntryImpl::ReadyForSparseIOImpl(const CompletionCallback& callback) {
-  DCHECK(sparse_.get());
   return sparse_->ReadyToUse(callback);
 }
 
@@ -706,67 +695,99 @@
 // read partial information from an entry (don't have to worry about returning
 // data related to a previous cache entry because the range was not fully
 // written before).
-EntryImpl::~EntryImpl() {
-  if (!backend_) {
-    entry_.clear_modified();
-    node_.clear_modified();
+EntryImplV3::~EntryImplV3() {
+  if (!backend_)
     return;
-  }
-  Log("~EntryImpl in");
+  Log("~EntryImplV3 in");
 
-  // Save the sparse info to disk. This will generate IO for this entry and
-  // maybe for a child entry, so it is important to do it before deleting this
-  // entry.
-  sparse_.reset();
+  DCHECK(!dirty_);
 
   // Remove this entry from the list of open entries.
-  backend_->OnEntryDestroyBegin(entry_.address());
+  backend_->OnEntryDestroyBegin(address_);
 
+  Trace("~EntryImplV3 out 0x%p", reinterpret_cast<void*>(this));
+  net_log_.EndEvent(net::NetLog::TYPE_DISK_CACHE_ENTRY_IMPL);
+  backend_->OnEntryDestroyEnd();
+
+  if (!destruction_callback_.is_null())
+    destruction_callback_.Run(net::OK);
+}
+
+void EntryImplV3::Cleanup() {
+  if (!backend_ || !dirty_)
+    return;
+
+  Log("Cleanup in");
+
+  bool success = true;
   if (doomed_) {
-    DeleteEntryData(true);
+    success = DeleteEntryData();
   } else {
 #if defined(NET_BUILD_STRESS_CACHE)
     SanityCheck();
 #endif
     net_log_.AddEvent(net::NetLog::TYPE_ENTRY_CLOSE);
-    bool ret = true;
     for (int index = 0; index < kNumStreams; index++) {
       if (user_buffers_[index].get()) {
-        if (!(ret = Flush(index, 0)))
-          LOG(ERROR) << "Failed to save user data";
+        int rv = Flush(index, 0);
+        if (rv != net::OK) {
+          DCHECK_EQ(rv, net::ERR_IO_PENDING);
+          PendingOperation op =
+              { PENDING_DONE, 0, 0, NULL, 0, CompletionCallback(), false };
+          pending_operations_.push(op);
+        }
       }
+      Addr address(entry_->data_addr[index]);
+      if (address.is_separate_file())
+        backend_->Close(this, address);
       if (unreported_size_[index]) {
         backend_->ModifyStorageSize(
-            entry_.Data()->data_size[index] - unreported_size_[index],
-            entry_.Data()->data_size[index]);
+            entry_->data_size[index] - unreported_size_[index],
+            entry_->data_size[index]);
       }
     }
 
-    if (!ret) {
-      // There was a failure writing the actual data. Mark the entry as dirty.
-      int current_id = backend_->GetCurrentEntryId();
-      node_.Data()->dirty = current_id == 1 ? -1 : current_id - 1;
-      node_.Store();
-    } else if (node_.HasData() && !dirty_ && node_.Data()->dirty) {
-      node_.Data()->dirty = 0;
-      node_.Store();
+    if (dirty_) {
+      entry_->state = ENTRY_USED;
+      WriteEntryData();
     }
+
+    backend_->OnEntryCleanup(this);
   }
 
-  Trace("~EntryImpl out 0x%p", reinterpret_cast<void*>(this));
-  net_log_.EndEvent(net::NetLog::TYPE_DISK_CACHE_ENTRY_IMPL);
-  backend_->OnEntryDestroyEnd();
+  if (success)
+    dirty_ = false;
+  Trace("~Cleanup out 0x%p", reinterpret_cast<void*>(this));
 }
 
-int EntryImpl::InternalReadData(int index, int offset,
-                                IOBuffer* buf, int buf_len,
-                                const CompletionCallback& callback) {
-  DCHECK(node_.Data()->dirty || read_only_);
+void EntryImplV3::WriteKey() {
+  DCHECK(!user_buffers_[kKeyIndex]);
+  DCHECK(!entry_->data_addr[kKeyIndex]);
+  DCHECK(!entry_->data_size[kKeyIndex]);
+
+  user_buffers_[kKeyIndex].reset(new UserBuffer(backend_.get()));
+  scoped_refptr<net::IOBuffer> buffer(new net::WrappedIOBuffer(key_.data()));
+
+  user_buffers_[kKeyIndex]->ForceSize(true);
+  bool rv = user_buffers_[kKeyIndex]->PreWrite(0, key_.size() + 1024);
+  DCHECK(rv);
+  user_buffers_[kKeyIndex]->ForceSize(false);
+  user_buffers_[kKeyIndex]->Write(0, buffer, key_.size());
+  UpdateSize(kKeyIndex, 0,  key_.size());
+}
+
+int EntryImplV3::ReadDataImpl(int index, int offset,
+                              IOBuffer* buf, int buf_len,
+                              PendingOperation* operation,
+                              const CompletionCallback& callback) {
   DVLOG(2) << "Read from " << index << " at " << offset << " : " << buf_len;
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
 
-  int entry_size = entry_.Data()->data_size[index];
+  if (index == kKeyIndex)
+    offset += key_.size();
+
+  int entry_size = entry_->data_size[index];
   if (offset >= entry_size || offset < 0 || !buf_len)
     return 0;
 
@@ -781,12 +802,15 @@
   if (offset + buf_len > entry_size)
     buf_len = entry_size - offset;
 
+  if (!buf_len)
+    return 0;
+
   UpdateRank(false);
 
   backend_->OnEvent(Stats::READ_DATA);
   backend_->OnRead(buf_len);
 
-  Addr address(entry_.Data()->data_addr[index]);
+  Addr address(entry_->data_addr[index]);
   int eof = address.is_initialized() ? entry_size : 0;
   if (user_buffers_[index].get() &&
       user_buffers_[index]->PreRead(eof, offset, &buf_len)) {
@@ -796,58 +820,24 @@
     return buf_len;
   }
 
-  address.set_value(entry_.Data()->data_addr[index]);
+  address.set_value(entry_->data_addr[index]);//? again?
   DCHECK(address.is_initialized());
   if (!address.is_initialized()) {
-    DoomImpl();
+    Doom();//?
     return net::ERR_FAILED;
   }
 
-  File* file = GetBackingFile(address, index);
-  if (!file) {
-    DoomImpl();
-    LOG(ERROR) << "No file for " << std::hex << address.value();
-    return net::ERR_FILE_NOT_FOUND;
-  }
-
-  size_t file_offset = offset;
-  if (address.is_block_file()) {
-    DCHECK_LE(offset + buf_len, kMaxBlockSize);
-    file_offset += address.start_block() * address.BlockSize() +
-                   kBlockHeaderSize;
-  }
-
-  SyncCallback* io_callback = NULL;
-  if (!callback.is_null()) {
-    io_callback = new SyncCallback(this, buf, callback,
-                                   net::NetLog::TYPE_ENTRY_READ_DATA);
-  }
-
-  TimeTicks start_async = TimeTicks::Now();
-
-  bool completed;
-  if (!file->Read(buf->data(), buf_len, file_offset, io_callback, &completed)) {
-    if (io_callback)
-      io_callback->Discard();
-    DoomImpl();
-    return net::ERR_CACHE_READ_FAILURE;
-  }
-
-  if (io_callback && completed)
-    io_callback->Discard();
-
-  if (io_callback)
-    ReportIOTime(kReadAsync1, start_async);
-
-  ReportIOTime(kRead, start);
-  return (completed || callback.is_null()) ? buf_len : net::ERR_IO_PENDING;
+  if (operation)
+    operation->action = PENDING_DONE;
+  backend_->ReadData(this, address, offset, buf, buf_len, callback);
+  return net::ERR_IO_PENDING;
 }
 
-int EntryImpl::InternalWriteData(int index, int offset,
-                                 IOBuffer* buf, int buf_len,
-                                 const CompletionCallback& callback,
-                                 bool truncate) {
-  DCHECK(node_.Data()->dirty || read_only_);
+int EntryImplV3::WriteDataImpl(int index, int offset,
+                               IOBuffer* buf, int buf_len,
+                               PendingOperation* operation,
+                               const CompletionCallback& callback,
+                               bool truncate) {
   DVLOG(2) << "Write to " << index << " at " << offset << " : " << buf_len;
   if (index < 0 || index >= kNumStreams)
     return net::ERR_INVALID_ARGUMENT;
@@ -870,114 +860,109 @@
     return net::ERR_FAILED;
   }
 
+  int actual_offset = (index == kKeyIndex) ? offset + key_.size() : offset;
+  
   TimeTicks start = TimeTicks::Now();
 
   // Read the size at this point (it may change inside prepare).
-  int entry_size = entry_.Data()->data_size[index];
-  bool extending = entry_size < offset + buf_len;
-  truncate = truncate && entry_size > offset + buf_len;
-  Trace("To PrepareTarget 0x%x", entry_.address().value());
-  if (!PrepareTarget(index, offset, buf_len, truncate))
-    return net::ERR_FAILED;
+  int entry_size = entry_->data_size[index];
+  bool extending = entry_size < actual_offset + buf_len;
+  truncate = truncate && entry_size > actual_offset + buf_len;
+  Trace("To PrepareTarget 0x%x", address_.value());
 
-  Trace("From PrepareTarget 0x%x", entry_.address().value());
+  int rv = PrepareTarget(index, actual_offset, buf_len, truncate);
+  if (rv == net::ERR_IO_PENDING) {   
+    if (operation) {
+      DCHECK_EQ(operation->action, PENDING_WRITE);
+      operation->action = PENDING_FLUSH;
+    } else {
+      PendingOperation op =
+          { PENDING_FLUSH, index, offset, buf, buf_len, callback, truncate };
+      pending_operations_.push(op);
+    }
+    return rv;
+  }
+
+  if (rv != net::OK)
+    return rv;
+
+  Trace("From PrepareTarget 0x%x", address_.value());
   if (extending || truncate)
-    UpdateSize(index, entry_size, offset + buf_len);
+    UpdateSize(index, entry_size, actual_offset + buf_len);
 
   UpdateRank(true);
+  OnEntryModified();
 
   backend_->OnEvent(Stats::WRITE_DATA);
   backend_->OnWrite(buf_len);
 
   if (user_buffers_[index].get()) {
     // Complete the operation locally.
-    user_buffers_[index]->Write(offset, buf, buf_len);
+    user_buffers_[index]->Write(actual_offset, buf, buf_len);
     ReportIOTime(kWrite, start);
     return buf_len;
   }
 
-  Addr address(entry_.Data()->data_addr[index]);
-  if (offset + buf_len == 0) {
+  Addr address(entry_->data_addr[index]);
+  if (actual_offset + buf_len == 0) {
     if (truncate) {
       DCHECK(!address.is_initialized());
     }
     return 0;
   }
 
-  File* file = GetBackingFile(address, index);
-  if (!file)
-    return net::ERR_FILE_NOT_FOUND;
+  if (address.is_separate_file() && (truncate || (extending && !buf_len)))
+    backend_->Truncate(this, address, actual_offset + buf_len);
 
-  size_t file_offset = offset;
-  if (address.is_block_file()) {
-    DCHECK_LE(offset + buf_len, kMaxBlockSize);
-    file_offset += address.start_block() * address.BlockSize() +
-                   kBlockHeaderSize;
-  } else if (truncate || (extending && !buf_len)) {
-    if (!file->SetLength(offset + buf_len))
-      return net::ERR_FAILED;
-  }
-
   if (!buf_len)
     return 0;
 
-  SyncCallback* io_callback = NULL;
-  if (!callback.is_null()) {
-    io_callback = new SyncCallback(this, buf, callback,
-                                   net::NetLog::TYPE_ENTRY_WRITE_DATA);
-  }
-
-  TimeTicks start_async = TimeTicks::Now();
-
-  bool completed;
-  if (!file->Write(buf->data(), buf_len, file_offset, io_callback,
-                   &completed)) {
-    if (io_callback)
-      io_callback->Discard();
-    return net::ERR_CACHE_WRITE_FAILURE;
-  }
-
-  if (io_callback && completed)
-    io_callback->Discard();
-
-  if (io_callback)
-    ReportIOTime(kWriteAsync1, start_async);
-
-  ReportIOTime(kWrite, start);
-  return (completed || callback.is_null()) ? buf_len : net::ERR_IO_PENDING;
+  if (operation)
+    operation->action = PENDING_DONE;
+  backend_->WriteData(this, address, actual_offset, buf, buf_len, callback);
+  return net::ERR_IO_PENDING;
 }
 
 // ------------------------------------------------------------------------
 
-bool EntryImpl::CreateDataBlock(int index, int size) {
+bool EntryImplV3::CreateDataBlock(int index, int size) {
   DCHECK(index >= 0 && index < kNumStreams);
 
-  Addr address(entry_.Data()->data_addr[index]);
+  Addr address(entry_->data_addr[index]);
   if (!CreateBlock(size, &address))
     return false;
 
-  entry_.Data()->data_addr[index] = address.value();
-  entry_.Store();
+  entry_->data_addr[index] = address.value();
   return true;
 }
 
-bool EntryImpl::CreateBlock(int size, Addr* address) {
+bool EntryImplV3::CreateBlock(int size, Addr* address) {
   DCHECK(!address->is_initialized());
   if (!backend_)
     return false;
 
   FileType file_type = Addr::RequiredFileType(size);
-  if (EXTERNAL == file_type) {
-    if (size > backend_->MaxFileSize())
-      return false;
-    if (!backend_->CreateExternalFile(address))
-      return false;
-  } else {
-    int num_blocks = Addr::RequiredBlocks(size, file_type);
+  if (EXTERNAL != file_type) {
+    int num_blocks = (size + Addr::BlockSizeForFileType(file_type) - 1) /
+                     Addr::BlockSizeForFileType(file_type);
 
-    if (!backend_->CreateBlock(file_type, num_blocks, address))
-      return false;
+    return backend_->CreateBlock(file_type, num_blocks, address);
   }
+
+  if (size > backend_->MaxFileSize())
+    return false;
+
+  Addr block_address;
+  if (!backend_->CreateBlock(BLOCK_FILES, 1, &block_address))
+    return false;
+  *address = block_address.AsExternal();
+
+  scoped_refptr<net::IOBufferWithSize> buffer(
+    new net::IOBufferWithSize(2 * sizeof(uint32)));
+  memcpy(buffer->data(), &entry_->hash, buffer->size());
+
+  backend_->WriteData(this, block_address, 0, buffer, buffer->size(),
+                      CompletionCallback());
   return true;
 }
 
@@ -987,47 +972,37 @@
 // entry will be left dirty... and at some point it will be discarded; it is
 // important that the entry doesn't keep a reference to this address, or we'll
 // end up deleting the contents of |address| once again.
-void EntryImpl::DeleteData(Addr address, int index) {
+void EntryImplV3::DeleteData(Addr address) {
   DCHECK(backend_);
   if (!address.is_initialized())
     return;
-  if (address.is_separate_file()) {
-    int failure = !DeleteCacheFile(backend_->GetFileName(address));
-    CACHE_UMA(COUNTS, "DeleteFailed", 0, failure);
-    if (failure) {
-      LOG(ERROR) << "Failed to delete " <<
-          backend_->GetFileName(address).value() << " from the cache.";
-    }
-    if (files_[index])
-      files_[index] = NULL;  // Releases the object.
-  } else {
-    backend_->DeleteBlock(address, true);
-  }
+  backend_->Delete(this, address);
 }
 
-void EntryImpl::UpdateRank(bool modified) {
+void EntryImplV3::UpdateRank(bool modified) {
   if (!backend_)
     return;
 
+  Time current = backend_->GetCurrentTime();
+  entry_->last_access_time = current.ToInternalValue();
+
+  if (modified)
+    entry_->last_modified_time = current.ToInternalValue();
+
   if (!doomed_) {
-    // Everything is handled by the backend.
     backend_->UpdateRank(this, modified);
     return;
   }
-
-  Time current = Time::Now();
-  node_.Data()->last_used = current.ToInternalValue();
-
-  if (modified)
-    node_.Data()->last_modified = current.ToInternalValue();
 }
 
-void EntryImpl::DeleteEntryData(bool everything) {
-  DCHECK(doomed_ || !everything);
+bool EntryImplV3::DeleteEntryData() {
+  DCHECK(doomed_);
+  if (!backend_->ShouldDeleteNow(this))
+    return false;
 
   if (GetEntryFlags() & PARENT_ENTRY) {
     // We have some child entries that must go away.
-    SparseControl::DeleteChildren(this);
+    SparseControlV3::DeleteChildren(this);
   }
 
   if (GetDataSize(0))
@@ -1035,37 +1010,23 @@
   if (GetDataSize(1))
     CACHE_UMA(COUNTS, "DeleteData", 0, GetDataSize(1));
   for (int index = 0; index < kNumStreams; index++) {
-    Addr address(entry_.Data()->data_addr[index]);
+    Addr address(entry_->data_addr[index]);
     if (address.is_initialized()) {
-      backend_->ModifyStorageSize(entry_.Data()->data_size[index] -
+      backend_->ModifyStorageSize(entry_->data_size[index] -
                                       unreported_size_[index], 0);
-      entry_.Data()->data_addr[index] = 0;
-      entry_.Data()->data_size[index] = 0;
-      entry_.Store();
-      DeleteData(address, index);
+      entry_->data_addr[index] = 0;
+      entry_->data_size[index] = 0;
+      dirty_ = true;
+      //entry_.Store();
+      DeleteData(address);
     }
   }
 
-  if (!everything)
-    return;
-
-  // Remove all traces of this entry.
-  backend_->RemoveEntry(this);
-
   // Note that at this point node_ and entry_ are just two blocks of data, and
   // even if they reference each other, nobody should be referencing them.
 
-  Addr address(entry_.Data()->long_key);
-  DeleteData(address, kKeyFileIndex);
-  backend_->ModifyStorageSize(entry_.Data()->key_len, 0);
-
-  backend_->DeleteBlock(entry_.address(), true);
-  entry_.Discard();
-
-  if (!LeaveRankingsBehind()) {
-    backend_->DeleteBlock(node_.address(), true);
-    node_.Discard();
-  }
+  backend_->Delete(this, address_);
+  return true;
 }
 
 // We keep a memory buffer for everything that ends up stored on a block file
@@ -1081,27 +1042,17 @@
 // reuse it for the new data. Keep in mind that the normal use pattern is quite
 // simple (write sequentially from the beginning), so we optimize for handling
 // that case.
-bool EntryImpl::PrepareTarget(int index, int offset, int buf_len,
-                              bool truncate) {
+int EntryImplV3::PrepareTarget(int index, int offset, int buf_len,
+                               bool truncate) {
   if (truncate)
     return HandleTruncation(index, offset, buf_len);
 
   if (!offset && !buf_len)
-    return true;
+    return net::OK;
 
-  Addr address(entry_.Data()->data_addr[index]);
-  if (address.is_initialized()) {
-    if (address.is_block_file() && !MoveToLocalBuffer(index))
-      return false;
+  if (!IsSimpleWrite(index, offset, buf_len))
+    return HandleOldData(index, offset, buf_len);
 
-    if (!user_buffers_[index].get() && offset < kMaxBlockSize) {
-      // We are about to create a buffer for the first 16KB, make sure that we
-      // preserve existing data.
-      if (!CopyToLocalBuffer(index))
-        return false;
-    }
-  }
-
   if (!user_buffers_[index].get())
     user_buffers_[index].reset(new UserBuffer(backend_.get()));
 
@@ -1111,23 +1062,25 @@
 // We get to this function with some data already stored. If there is a
 // truncation that results on data stored internally, we'll explicitly
 // handle the case here.
-bool EntryImpl::HandleTruncation(int index, int offset, int buf_len) {
-  Addr address(entry_.Data()->data_addr[index]);
+int EntryImplV3::HandleTruncation(int index, int offset, int buf_len) {
+  Addr address(entry_->data_addr[index]);
 
-  int current_size = entry_.Data()->data_size[index];
+  int current_size = entry_->data_size[index];
   int new_size = offset + buf_len;
+  DCHECK_LT(new_size, current_size);
 
   if (!new_size) {
     // This is by far the most common scenario.
-    backend_->ModifyStorageSize(current_size - unreported_size_[index], 0);
-    entry_.Data()->data_addr[index] = 0;
-    entry_.Data()->data_size[index] = 0;
+    backend_->ModifyStorageSize(current_size - unreported_size_[index], 0);//updatesize()
+    entry_->data_addr[index] = 0;
+    entry_->data_size[index] = 0;
     unreported_size_[index] = 0;
-    entry_.Store();
-    DeleteData(address, index);
+    OnEntryModified();
+    //entry_->Store();
+    DeleteData(address);
 
     user_buffers_[index].reset();
-    return true;
+    return net::OK;
   }
 
   // We never postpone truncating a file, if there is one, but we may postpone
@@ -1140,21 +1093,24 @@
         // Just truncate our buffer.
         DCHECK_LT(new_size, user_buffers_[index]->End());
         user_buffers_[index]->Truncate(new_size);
-        return true;
+        return net::OK;
       }
 
       // Just discard our buffer.
-      user_buffers_[index]->Reset();
+      user_buffers_[index].reset();
       return PrepareBuffer(index, offset, buf_len);
     }
 
     // There is some overlap or we need to extend the file before the
     // truncation.
-    if (offset > user_buffers_[index]->Start())
-      user_buffers_[index]->Truncate(new_size);
-    UpdateSize(index, current_size, new_size);
-    if (!Flush(index, 0))
-      return false;
+    if (new_size > user_buffers_[index]->Start()) {
+      if (offset > user_buffers_[index]->Start())
+        user_buffers_[index]->Truncate(new_size);
+      UpdateSize(index, current_size, new_size);
+      int rv = Flush(index, 0);
+      if (rv != net::OK)
+        return rv;
+    }
     user_buffers_[index].reset();
   }
 
@@ -1162,80 +1118,96 @@
   DCHECK(!user_buffers_[index].get());
   DCHECK(address.is_initialized());
 
-  if (new_size > kMaxBlockSize)
-    return true;  // Let the operation go directly to disk.
+  if (!IsSimpleWrite(index, offset, buf_len))
+    return net::OK;  // Let the operation go directly to disk.
 
-  return ImportSeparateFile(index, offset + buf_len);
+  if (address.is_separate_file())
+    backend_->Truncate(this, address, offset + buf_len);
+
+  if (!user_buffers_[index].get())
+    user_buffers_[index].reset(new UserBuffer(backend_.get()));
+
+  return PrepareBuffer(index, offset, buf_len);
 }
 
-bool EntryImpl::CopyToLocalBuffer(int index) {
-  Addr address(entry_.Data()->data_addr[index]);
-  DCHECK(!user_buffers_[index].get());
-  DCHECK(address.is_initialized());
+bool EntryImplV3::IsSimpleWrite(int index, int offset, int buf_len) {
+  Addr address(entry_->data_addr[index]);
+  if (!address.is_initialized())
+    return true;
 
-  int len = std::min(entry_.Data()->data_size[index], kMaxBlockSize);
-  user_buffers_[index].reset(new UserBuffer(backend_.get()));
-  user_buffers_[index]->Write(len, NULL, 0);
+  if (address.is_block_file() && (offset + buf_len > kMaxBlockSize))// check limit
+    return false;
 
-  File* file = GetBackingFile(address, index);
-  int offset = 0;
+  if (!user_buffers_[index].get())
+    return true;
 
-  if (address.is_block_file())
-    offset = address.start_block() * address.BlockSize() + kBlockHeaderSize;
+  if ((offset >= user_buffers_[index]->Start()) &&
+      (offset <= user_buffers_[index]->End())) {
+    return true;
+  }
 
-  if (!file ||
-      !file->Read(user_buffers_[index]->Data(), len, offset, NULL, NULL)) {
-    user_buffers_[index].reset();
-    return false;
-  }
-  return true;
+  return offset > entry_->data_size[index];
 }
 
-bool EntryImpl::MoveToLocalBuffer(int index) {
-  if (!CopyToLocalBuffer(index))
-    return false;
+int EntryImplV3::HandleOldData(int index, int offset, int buf_len) {
+  Addr address(entry_->data_addr[index]);
+  DCHECK(address.is_initialized());
 
-  Addr address(entry_.Data()->data_addr[index]);
-  entry_.Data()->data_addr[index] = 0;
-  entry_.Store();
-  DeleteData(address, index);
+  if (address.is_block_file() && (offset + buf_len > kMaxBlockSize)) {// check limit
+    if (!GetAdjustedSize(index, offset) || !GetDataSize(index)) {
+      // There's nothing to save from the old data.
+      user_buffers_[index].reset();
+      DCHECK(!user_buffers_[kKeyIndex]);
+      DeleteData(address);
+      entry_->data_addr[kKeyIndex] = 0;
+      entry_->data_size[kKeyIndex] = 0;
+      WriteKey();
+      return PrepareBuffer(index, offset, buf_len);
+    }
+    // We have to move the data to a new file.
+    Addr new_address;
+    if (!CreateBlock(kMaxBlockSize * 2, &new_address))
+      return net::ERR_FAILED;
 
-  // If we lose this entry we'll see it as zero sized.
-  int len = entry_.Data()->data_size[index];
-  backend_->ModifyStorageSize(len - unreported_size_[index], 0);
-  unreported_size_[index] = len;
-  return true;
-}
+    backend_->MoveData(this, address, new_address, entry_->data_size[index],
+                        callback_);
+    entry_->data_addr[index] = new_address.value();
+    return net::ERR_IO_PENDING;
+  }
 
-bool EntryImpl::ImportSeparateFile(int index, int new_size) {
-  if (entry_.Data()->data_size[index] > new_size)
-    UpdateSize(index, entry_.Data()->data_size[index], new_size);
+  int rv = Flush(index, 0);
+  if (rv != net::OK)
+    return rv;
 
-  return MoveToLocalBuffer(index);
+  user_buffers_[index].reset();  // Don't use a local buffer.
+  return net::OK;
 }
 
-bool EntryImpl::PrepareBuffer(int index, int offset, int buf_len) {
+int EntryImplV3::PrepareBuffer(int index, int offset, int buf_len) {
   DCHECK(user_buffers_[index].get());
+  int rv = net::OK;
   if ((user_buffers_[index]->End() && offset > user_buffers_[index]->End()) ||
-      offset > entry_.Data()->data_size[index]) {
+      offset > entry_->data_size[index]) {
     // We are about to extend the buffer or the file (with zeros), so make sure
     // that we are not overwriting anything.
-    Addr address(entry_.Data()->data_addr[index]);
+    Addr address(entry_->data_addr[index]);
     if (address.is_initialized() && address.is_separate_file()) {
-      if (!Flush(index, 0))
-        return false;
+      rv = Flush(index, 0);
+      if (rv != net::OK)
+        return rv;
       // There is an actual file already, and we don't want to keep track of
       // its length so we let this operation go straight to disk.
       // The only case when a buffer is allowed to extend the file (as in fill
       // with zeros before the start) is when there is no file yet to extend.
       user_buffers_[index].reset();
-      return true;
+      return rv;
     }
   }
 
   if (!user_buffers_[index]->PreWrite(offset, buf_len)) {
-    if (!Flush(index, offset + buf_len))
-      return false;
+    rv = Flush(index, offset + buf_len);
+    if (rv != net::OK)
+      return rv;
 
     // Lets try again.
     if (offset > user_buffers_[index]->End() ||
@@ -1246,89 +1218,99 @@
       user_buffers_[index].reset();
     }
   }
-  return true;
+  return rv;
 }
 
-bool EntryImpl::Flush(int index, int min_len) {
-  Addr address(entry_.Data()->data_addr[index]);
-  DCHECK(user_buffers_[index].get());
-  DCHECK(!address.is_initialized() || address.is_separate_file());
+int EntryImplV3::Flush(int index, int min_len) {
+  Addr address(entry_->data_addr[index]);
+  if (!user_buffers_[index].get())
+    return net::OK;
+
+  //DCHECK(!address.is_initialized() || address.is_separate_file());
   DVLOG(3) << "Flush";
 
-  int size = std::max(entry_.Data()->data_size[index], min_len);
+  int size = std::max(entry_->data_size[index], min_len);
   if (size && !address.is_initialized() && !CreateDataBlock(index, size))
-    return false;
+    return net::ERR_FAILED;
 
-  if (!entry_.Data()->data_size[index]) {
+  if (!entry_->data_size[index]) {
     DCHECK(!user_buffers_[index]->Size());
-    return true;
+    return net::OK;
   }
 
-  address.set_value(entry_.Data()->data_addr[index]);
+  address.set_value(entry_->data_addr[index]);
 
   int len = user_buffers_[index]->Size();
   int offset = user_buffers_[index]->Start();
   if (!len && !offset)
-    return true;
+    return net::OK;
 
-  if (address.is_block_file()) {
-    DCHECK_EQ(len, entry_.Data()->data_size[index]);
-    DCHECK(!offset);
-    offset = address.start_block() * address.BlockSize() + kBlockHeaderSize;
+  if (!len) {
+    if (address.is_separate_file()) {
+      backend_->Truncate(this, address, offset);
+      return net::OK;
+    }
+    user_buffers_[index]->Rebase();
+    len = offset;
+    offset = 0;
   }
 
-  File* file = GetBackingFile(address, index);
-  if (!file)
-    return false;
-
-  if (!file->Write(user_buffers_[index]->Data(), len, offset, NULL, NULL))
-    return false;
-  user_buffers_[index]->Reset();
-
-  return true;
+  backend_->WriteData(this, address, offset, user_buffers_[index]->Get(),
+                      len, callback_);
+  user_buffers_[index].reset();
+  return net::ERR_IO_PENDING;
 }
 
-void EntryImpl::UpdateSize(int index, int old_size, int new_size) {
-  if (entry_.Data()->data_size[index] == new_size)
+void EntryImplV3::UpdateSize(int index, int old_size, int new_size) {
+  if (entry_->data_size[index] == new_size)
     return;
 
   unreported_size_[index] += new_size - old_size;
-  entry_.Data()->data_size[index] = new_size;
-  entry_.set_modified();
+  entry_->data_size[index] = new_size;
+  OnEntryModified();
 }
 
-int EntryImpl::InitSparseData() {
-  if (sparse_.get())
-    return net::OK;
+void EntryImplV3::WriteEntryData() {
+  CacheEntryBlockV3 entry_block;
+  entry_block.SetData(entry_.get());
+  entry_block.UpdateHash();
 
-  // Use a local variable so that sparse_ never goes from 'valid' to NULL.
-  scoped_ptr<SparseControl> sparse(new SparseControl(this));
-  int result = sparse->Init();
-  if (net::OK == result)
-    sparse_.swap(sparse);
+  scoped_refptr<net::IOBufferWithSize> buffer(
+      new net::IOBufferWithSize(sizeof(EntryRecord)));
+  memcpy(buffer->data(), entry_.get(), buffer->size());
 
-  return result;
+  backend_->WriteData(this, address_, 0, buffer, buffer->size(),
+                      CompletionCallback());
 }
 
-void EntryImpl::SetEntryFlags(uint32 flags) {
-  entry_.Data()->flags |= flags;
-  entry_.set_modified();
+void EntryImplV3::SetEntryFlags(uint32 flags) {
+  entry_->flags |= flags;
+  dirty_ = true;
 }
 
-uint32 EntryImpl::GetEntryFlags() {
-  return entry_.Data()->flags;
+uint32 EntryImplV3::GetEntryFlags() {
+  return entry_->flags;
 }
 
-void EntryImpl::GetData(int index, char** buffer, Addr* address) {
+void EntryImplV3::OnEntryModified() {
+  if (modified_)
+    return;
+  DCHECK(!read_only_);
+  dirty_ = true;
+  modified_ = true;
+  if (backend_)
+    backend_->OnEntryModified(this);
+}
+
+void EntryImplV3::GetData(int index, scoped_refptr<IOBuffer>* buffer, Addr* address) {
   DCHECK(backend_);
   if (user_buffers_[index].get() && user_buffers_[index]->Size() &&
       !user_buffers_[index]->Start()) {
     // The data is already in memory, just copy it and we're done.
-    int data_len = entry_.Data()->data_size[index];
+    int data_len = entry_->data_size[index];
     if (data_len <= user_buffers_[index]->Size()) {
       DCHECK(!user_buffers_[index]->Start());
-      *buffer = new char[data_len];
-      memcpy(*buffer, user_buffers_[index]->Data(), data_len);
+      *buffer = user_buffers_[index]->Get();
       return;
     }
   }
@@ -1336,17 +1318,17 @@
   // Bad news: we'd have to read the info from disk so instead we'll just tell
   // the caller where to read from.
   *buffer = NULL;
-  address->set_value(entry_.Data()->data_addr[index]);
+  address->set_value(entry_->data_addr[index]);
   if (address->is_initialized()) {
     // Prevent us from deleting the block from the backing store.
-    backend_->ModifyStorageSize(entry_.Data()->data_size[index] -
+    backend_->ModifyStorageSize(entry_->data_size[index] -
                                     unreported_size_[index], 0);
-    entry_.Data()->data_addr[index] = 0;
-    entry_.Data()->data_size[index] = 0;
+    entry_->data_addr[index] = 0;
+    entry_->data_size[index] = 0;
   }
 }
 
-void EntryImpl::ReportIOTime(Operation op, const base::TimeTicks& start) {
+void EntryImplV3::ReportIOTime(Operation op, const base::TimeTicks& start) {
   if (!backend_)
     return;
 
@@ -1377,19 +1359,69 @@
   }
 }
 
-void EntryImpl::Log(const char* msg) {
-  int dirty = 0;
-  if (node_.HasData()) {
-    dirty = node_.Data()->dirty;
-  }
+void EntryImplV3::Log(const char* msg) {
+  Trace("%s 0x%p 0x%x", msg, reinterpret_cast<void*>(this), address_);
+  Trace("  data: 0x%x 0x%x", entry_->data_addr[0], entry_->data_addr[1]);
+  Trace("  doomed: %d", doomed_);
+}
 
-  Trace("%s 0x%p 0x%x 0x%x", msg, reinterpret_cast<void*>(this),
-        entry_.address().value(), node_.address().value());
+void EntryImplV3::OnIOComplete(int result) {
+  DCHECK_NE(result, net::ERR_IO_PENDING);
+  DCHECK(!pending_operations_.empty());
+  while (result != net::ERR_IO_PENDING) {
+    bool finished = false;
+    PendingOperation& next = pending_operations_.front();
+    switch (next.action) {
+      case PENDING_FLUSH:
+        if (result < 0)
+          finished = true;
+        next.action = PENDING_WRITE;
+        break;
+      case PENDING_READ:
+        result = ReadDataImpl(next.index, next.offset, next.buf,
+                              next.buf_len, &next, callback_);
+        if (result != net::ERR_IO_PENDING)
+          finished = true;
+        break;
+      case PENDING_WRITE:
+        result = WriteDataImpl(next.index, next.offset, next.buf,
+                               next.buf_len, &next, callback_,
+                               next.truncate);
+        if (result != net::ERR_IO_PENDING)
+          finished = true;
+        break;
+      case PENDING_CLEANUP:
+        Cleanup();
+        finished = true;
+        break;
+      case PENDING_DONE:
+        finished = true;
+        break;
+      default: NOTREACHED();
+    }
+    if (finished) {
+      next.buf = NULL;
+      if (!next.callback.is_null())
+        next.callback.Run(result);
+      pending_operations_.pop();
 
-  Trace("  data: 0x%x 0x%x 0x%x", entry_.Data()->data_addr[0],
-        entry_.Data()->data_addr[1], entry_.Data()->long_key);
+      if (pending_operations_.empty()) {
+        if (dirty_ && HasOneRef()) {
+          // One of the pending operations modified this entry after the last
+          // Close... issue an extra cleanup.
+          Cleanup();
+        }
+        break;
+      }
 
-  Trace("  doomed: %d 0x%x", doomed_, dirty);
+      // Cleanup may issue multiple flushes so there may be multiple pending
+      // callbacks already in flight. Make sure we wait for them.
+      next = pending_operations_.front();
+      DCHECK_NE(next.action, PENDING_FLUSH);
+      if (next.action == PENDING_DONE)
+        break;
+    }
+  }
 }
 
 }  // namespace disk_cache