Disk cache: Reference CL for the implementation of file format version 3.

net/disk_cache/v3/backend_work_item.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/v3/backend_work_item.h"
+
+#include "base/hash.h"
+#include "base/sha1.h"
+#include "net/base/net_errors.h"
+#include "net/disk_cache/errors.h"
+#include "net/disk_cache/file.h"
+#include "net/disk_cache/storage_block-inl.h"
+#include "net/disk_cache/v3/backend_worker.h"
+#include "net/disk_cache/v3/entry_impl_v3.h"
+
+namespace {
+
+// Simple adaptor for the sha1 interface.       
+void ComputeCryptoHash(const std::string& source,
+                       disk_cache::ShortEntryRecord* record) {
+  DCHECK(!source.empty());
+  base::SHA1HashBytes(reinterpret_cast<const unsigned char*>(source.data()),
+                      source.size(),
+                      reinterpret_cast<unsigned char*>(record->long_hash));
+}
+
+bool CryptoHashMatches(const std::string& source,
+                       const disk_cache::ShortEntryRecord& record) {
+  DCHECK(!source.empty());
+  unsigned char result[20];
+  base::SHA1HashBytes(reinterpret_cast<const unsigned char*>(source.data()),    
+                      source.size(), result);
+
+  return !memcmp(result, record.long_hash, sizeof(result));
+}
+
+}  // namespace
+
+// ------------------------------------------------------------------------
+
+namespace disk_cache {
+
+class BackendImplV3::IOCallback : public disk_cache::FileIOCallback {
+ public:
+  explicit IOCallback(BackendImplV3::WorkItem* work_item);
+  virtual ~IOCallback() {}
+
+  // FileIOCallback implementation.
+  virtual void OnFileIOComplete(int bytes_copied) OVERRIDE;
+  void Discard();
+
+ private:
+  // Even though we need the work item alive until the operation completes, we
+  // don't grab an extra reference because the work item itself keeps an extra
+  // reference until it reaches the main thread again.
+  BackendImplV3::WorkItem* work_item_;
+
+  DISALLOW_COPY_AND_ASSIGN(IOCallback);
+};
+
+BackendImplV3::IOCallback::IOCallback(BackendImplV3::WorkItem* work_item)
+    : work_item_(work_item) {
+}
+
+void BackendImplV3::IOCallback::OnFileIOComplete(int bytes_copied) {
+  if (work_item_)
+    work_item_->DoLoop(bytes_copied);
+
+  delete this;
+}
+
+void BackendImplV3::IOCallback::Discard() {
+  work_item_ = NULL;
+  OnFileIOComplete(0);
+}
+
+// ------------------------------------------------------------------------
+
+BackendImplV3::WorkItem::WorkItem(WorkType type)
+  : type_(type),
+    result_(0),
+    flags_(0) {//init everything
+}
+
+void BackendImplV3::WorkItem::Start(BackendImplV3::Worker* worker) {
+  Trace("Work 0x%p %d", this, type());
+  worker_ = worker;
+  switch (type_) {
+    case WORK_INIT:
+      return CompleteItem(worker_->Init(flags_, &init_result_));
+    case WORK_RESTART:
+      return CompleteItem(worker_->Restart(flags_, &init_result_));
+    case WORK_GROW_INDEX:
+      return CompleteItem(worker_->GrowIndex(flags_, &init_result_));
+    case WORK_GROW_FILES:
+      return CompleteItem(worker_->GrowFiles(flags_, &init_result_));
+    case WORK_NONE:
+      return CompleteItem(ERR_NO_ERROR);
+    case WORK_OPEN_ENTRY:
+      next_state_ = STATE_OPEN_ENTRY;
+      break;
+    case WORK_READ_DATA:
+      next_state_ = STATE_READ_DATA;
+      break;
+    case WORK_WRITE_DATA:
+      next_state_ = STATE_WRITE_DATA;
+      break;
+    case WORK_MOVE_DATA:
+      next_state_ = STATE_MOVE_DATA;
+      break;
+    case WORK_TRUNCATE:
+      next_state_ = STATE_TRUNCATE_DATA;
+      break;
+    case WORK_DELETE:
+      return CompleteItem(worker_->Delete(address_));
+    case WORK_CLOSE:
+      return CompleteItem(worker_->Close(address_));
+    default: NOTREACHED();
+  }
+  DoLoop(ERR_NO_ERROR);
+}
+
+void BackendImplV3::WorkItem::DoLoop(int result) {
+  DCHECK(next_state_ != STATE_NONE);
+  if (!worker_->IsValid())
+    return CompleteItem(result);
+
+  int rv = result;
+  do {
+    State state = next_state_;
+    next_state_ = STATE_NONE;
+    switch (state) {
+      case STATE_OPEN_ENTRY:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoOpenEntry();
+        break;
+      case STATE_OPEN_ENTRY_COMPLETE:
+        rv = DoOpenEntryComplete(rv);
+        break;
+      case STATE_READ_KEY:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoReadKey();
+        break;
+      case STATE_READ_KEY_COMPLETE:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoReadKeyComplete();
+        break;
+      case STATE_READ_DATA:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoReadData();
+        break;
+      case STATE_READ_DATA_COMPLETE:
+        rv = DoReadDataComplete(rv);
+        break;
+      case STATE_WRITE_DATA:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoWriteData();
+        break;
+      case STATE_WRITE_DATA_COMPLETE:
+        rv = DoWriteDataComplete(rv);
+        break;
+      case STATE_MOVE_DATA:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoMoveData();
+        break;
+      case STATE_TRUNCATE_DATA:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoTruncateData();
+        break;
+      case STATE_COPY_ENTRY:
+        DCHECK_EQ(ERR_NO_ERROR, rv);
+        rv = DoCopyEntry();
+        break;
+      case STATE_COPY_ENTRY_COMPLETE:
+        rv = DoCopyEntryComplete(rv);
+        break;
+    }
+  } while (rv != ERR_PENDING && next_state_ != STATE_NONE);
+
+  if (rv != ERR_PENDING)
+    CompleteItem(rv);
+}
+
+void BackendImplV3::WorkItem::OnDone() {
+  closure_.Run(this);
+}
+
+// ------------------------------------------------------------------------
+
+BackendImplV3::WorkItem::~WorkItem() {
+}
+
+void BackendImplV3::WorkItem::CompleteItem(int result) {
+  Trace("Work done 0x%p %d %d", this, type(), result);
+  result_ = result;
+  entry_block_.reset();  // Release resources while on the worker thread.
+  worker_->DoneWithItem(this);
+}
+
+int BackendImplV3::WorkItem::DoOpenEntry() {
+  next_state_ = STATE_OPEN_ENTRY_COMPLETE;
+  for (; entries_.current < entries_.cells.size(); entries_.current++) {
+    Addr address = entries_.cells[entries_.current].GetAddress();
+    if (entries_.cells[entries_.current].group() == ENTRY_EVICTED) {
+      if (flags_ & WORK_FOR_RESURRECT)
+        return LoadShortEntryBlock(address);
+      continue;
+    }
+
+    if (flags_ & WORK_FOR_RESURRECT)
+      continue;
+    return LoadEntryBlock(address);
+  }
+  next_state_ = STATE_NONE;
+  return ERR_OPERATION_FAILED;
+}
+
+int BackendImplV3::WorkItem::DoOpenEntryComplete(int result) {
+  if (entries_.cells[entries_.current].group() == ENTRY_EVICTED) {
+    if (result != static_cast<int>(sizeof(ShortEntryRecord)))
+      return ERR_READ_FAILURE;
+
+    if (!EntryImplV3::DeletedSanityCheck(*short_entry_block_->Data()))
+      return ERR_INVALID_ENTRY;
+  } else {
+    if (result != static_cast<int>(sizeof(EntryRecord)))
+      return ERR_READ_FAILURE;
+
+    if (!EntryImplV3::BasicSanityCheck(*entry_block_->Data()))
+      return ERR_INVALID_ENTRY;
+  }
+
+  if (entries_.cells[entries_.current].group() == ENTRY_EVICTED) {
+    DCHECK(!(flags_ & WORK_FOR_EVICT));
+    if (CryptoHashMatches(key_, *short_entry_block_->Data())) {
+      // We have a match.
+      short_entry_record_.reset(short_entry_block_->ReleaseData());
+      return ERR_NO_ERROR;
+    }
+  } else {
+    next_state_ = STATE_READ_KEY;
+    return ERR_NO_ERROR;
+  }
+
+  next_state_ = STATE_OPEN_ENTRY;
+  entries_.current++;
+  return ERR_NO_ERROR;
+}
+
+int BackendImplV3::WorkItem::DoReadKey() {
+  address_.set_value(entry_block_->Data()->data_addr[0]);
+  offset_ = 0;
+  buffer_ = new net::IOBuffer(entry_block_->Data()->key_len);
+  buffer_len_ = entry_block_->Data()->key_len;
+
+  next_state_ = STATE_READ_DATA;
+  return ERR_NO_ERROR;
+}
+
+int BackendImplV3::WorkItem::DoReadKeyComplete() {
+  std::string key(buffer_->data(), buffer_len_);
+  uint32 hash = base::Hash(key);
+  Trace("DoReadKeyComplete hash 0x%x, 0x%p", hash, this);
+  DCHECK_EQ(hash, entries_.cells[entries_.current].hash());
+  if (flags() & WORK_FOR_ITERATION)
+    key_ = key;
+
+  if (flags_ & WORK_FOR_EVICT) {
+    key_ = key;
+    if (!(flags_ & WORK_NO_COPY)) {
+      next_state_ = STATE_COPY_ENTRY;
+      return ERR_NO_ERROR;
+    }
+  }
+
+  if (key == key_) {
+    // We have a match.
+    entry_record_.reset(entry_block_->ReleaseData());
+    return ERR_NO_ERROR;
+  }
+
+  next_state_ = STATE_OPEN_ENTRY;
+  entries_.current++;
+  return ERR_NO_ERROR;
+}
+
+int BackendImplV3::WorkItem::DoReadData() {
+  disk_cache::File* file = worker_->GetBackingFile(address_, false);
+  if (!file)
+    return net::ERR_FILE_NOT_FOUND;
+
+
+  size_t file_offset = offset_;
+  if (address_.is_block_file()) {
+    DCHECK_LE(offset_ + buffer_len_, kMaxBlockSize);
+    file_offset += address_.start_block() * address_.BlockSize();
+  }
+  DCHECK(buffer_len_);
+
+  bool completed;
+  IOCallback* callback = new IOCallback(this);
+
+  if (!file->Read(buffer_->data(), buffer_len_, file_offset, callback,
+                  &completed)) {
+    callback->Discard();
+    return net::ERR_CACHE_READ_FAILURE;
+  }
+  next_state_ = STATE_READ_DATA_COMPLETE;
+
+  if (completed) {
+    callback->Discard();
+    return NO_ERROR;
+  }
+
+  return ERR_PENDING;
+}
+
+int BackendImplV3::WorkItem::DoReadDataComplete(int result) {
+  if (result != buffer_len_)
+    return net::ERR_CACHE_READ_FAILURE;
+
+  if (type() == WORK_OPEN_ENTRY) {
+    next_state_ = STATE_READ_KEY_COMPLETE;
+    return ERR_NO_ERROR;
+  }
+
+  return result;
+}
+
+int BackendImplV3::WorkItem::DoWriteData() {
+  disk_cache::File* file = worker_->GetBackingFile(address_, true);
+  if (!file)
+    return net::ERR_CACHE_WRITE_FAILURE;
+
+  DCHECK(buffer_len_);
+
+  size_t file_offset = offset_;
+  if (address_.is_block_file()) {
+    DCHECK_LE(offset_ + buffer_len_, kMaxBlockSize);
+    file_offset += address_.start_block() * address_.BlockSize();
+  }
+
+  bool completed;
+  IOCallback* callback = new IOCallback(this);
+
+  if (!file->Write(buffer_->data(), buffer_len_, file_offset, callback,
+                   &completed)) {
+    callback->Discard();
+    return net::ERR_CACHE_WRITE_FAILURE;
+  }
+  next_state_ = STATE_WRITE_DATA_COMPLETE;
+
+  if (completed) {
+    callback->Discard();
+    return NO_ERROR;
+  }
+
+  return ERR_PENDING;
+}
+
+int BackendImplV3::WorkItem::DoWriteDataComplete(int result) {
+  if (result != buffer_len_)
+    return net::ERR_CACHE_WRITE_FAILURE;
+
+  return result;
+}
+
+int BackendImplV3::WorkItem::DoMoveData() {
+  disk_cache::File* file = worker_->GetBackingFile(address_, false);
+  if (!file)
+    return ERR_OPERATION_FAILED;
+
+  DCHECK(buffer_len_);
+
+  if (!address_.is_block_file()) {
+    NOTREACHED();
+    return ERR_OPERATION_FAILED;
+  }
+
+  offset_ = 0;
+  size_t file_offset = 0;
+  DCHECK_LE(buffer_len_, kMaxBlockSize);
+  file_offset += address_.start_block() * address_.BlockSize();
+
+  buffer_ = new net::IOBufferWithSize(buffer_len_);
+
+  // We could optimize this to be an async read, but we'd have to do that from
+  // the main thread, not from here.
+  if (!file->Read(buffer_->data(), buffer_len_, file_offset))
+    return ERR_WRITE_FAILURE;
+
+  address_ = address2_;
+  next_state_ = STATE_WRITE_DATA;
+  return NO_ERROR;
+}
+
+int BackendImplV3::WorkItem::DoTruncateData() {
+  if (address_.is_block_file())
+    return ERR_OPERATION_FAILED;
+
+  disk_cache::File* file = worker_->GetBackingFile(address_, false);
+  if (!file)
+    return ERR_OPERATION_FAILED;
+
+  if (!file->SetLength(offset_))
+    return ERR_OPERATION_FAILED;
+  
+  return ERR_NO_ERROR;
+}
+
+int BackendImplV3::WorkItem::DoCopyEntry() {
+  next_state_ = STATE_COPY_ENTRY_COMPLETE;
+  Addr address = entries_.cells[1].GetAddress();
+  short_entry_block_.reset(
+      new CacheShortEntryBlock(worker_->GetMappedFile(address), address));
+
+  ShortEntryRecord* short_record = short_entry_block_->Data();
+  EntryRecord* long_record = entry_block_->Data();
+
+  short_record->hash = long_record->hash;
+  short_record->reuse_count = long_record->reuse_count;
+  short_record->refetch_count = long_record->refetch_count;
+  short_record->refetch_count = long_record->refetch_count;
+  short_record->key_len = long_record->key_len;
+  short_record->last_access_time = long_record->last_access_time;
+  ComputeCryptoHash(key_, short_record);
+
+  bool completed;
+  IOCallback* callback = new IOCallback(this);
+  if (!short_entry_block_->Store(callback, &completed)) {
+    callback->Discard();
+    next_state_ = STATE_NONE;
+    return ERR_OPERATION_FAILED;
+  }
+
+  if (completed) {
+    callback->Discard();
+    return ERR_NO_ERROR;
+  }
+
+  return ERR_PENDING;
+}
+
+int BackendImplV3::WorkItem::DoCopyEntryComplete(int result) {
+  if (result != static_cast<int>(sizeof(ShortEntryRecord)))
+    return ERR_READ_FAILURE;
+
+  entry_record_.reset(entry_block_->ReleaseData());
+  return ERR_NO_ERROR;
+}
+
+int BackendImplV3::WorkItem::LoadEntryBlock(Addr address) {
+  entry_block_.reset(new CacheEntryBlockV3(worker_->GetMappedFile(address),
+                                           address));
+  bool completed;
+  IOCallback* callback = new IOCallback(this);
+  if (!entry_block_->Load(callback, &completed)) {
+    callback->Discard();
+    next_state_ = STATE_NONE;
+    return ERR_OPERATION_FAILED;
+  }
+
+  if (completed) {
+    callback->Discard();
+    return ERR_NO_ERROR;
+  }
+
+  return ERR_PENDING;
+}
+
+int BackendImplV3::WorkItem::LoadShortEntryBlock(Addr address) {
+  short_entry_block_.reset(
+      new CacheShortEntryBlock(worker_->GetMappedFile(address), address));
+  bool completed;
+  IOCallback* callback = new IOCallback(this);
+  if (!short_entry_block_->Load(callback, &completed)) {
+    callback->Discard();
+    next_state_ = STATE_NONE;
+    return ERR_OPERATION_FAILED;
+  }
+
+  if (completed) {
+    callback->Discard();
+    return ERR_NO_ERROR;
+  }
+
+  return ERR_PENDING;
+}
+
+}  // namespace disk_cache