[Storage] Blob Storage Refactoring pt 1

storage/common/blob/shareable_file_reference.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 "storage/common/blob/shareable_file_reference.h"
-
-#include <map>
-
-#include "base/lazy_instance.h"
-#include "base/message_loop/message_loop_proxy.h"
-#include "base/task_runner.h"
-#include "base/threading/non_thread_safe.h"
-
-namespace storage {
-
-namespace {
-
-// A shareable file map with enforcement of thread checker.
-class ShareableFileMap : public base::NonThreadSafe {
- public:
-  typedef std::map<base::FilePath, ShareableFileReference*> FileMap;
-  typedef FileMap::iterator iterator;
-  typedef FileMap::key_type key_type;
-  typedef FileMap::value_type value_type;
-
-  ShareableFileMap() {}
-
-  ~ShareableFileMap() {
-    DetachFromThread();
-  }
-
-  iterator Find(key_type key) {
-    DCHECK(CalledOnValidThread());
-    return file_map_.find(key);
-  }
-
-  iterator End() {
-    DCHECK(CalledOnValidThread());
-    return file_map_.end();
-  }
-
-  std::pair<iterator, bool> Insert(value_type value) {
-    DCHECK(CalledOnValidThread());
-    return file_map_.insert(value);
-  }
-
-  void Erase(key_type key) {
-    DCHECK(CalledOnValidThread());
-    file_map_.erase(key);
-  }
-
- private:
-  FileMap file_map_;
-  DISALLOW_COPY_AND_ASSIGN(ShareableFileMap);
-};
-
-base::LazyInstance<ShareableFileMap> g_file_map = LAZY_INSTANCE_INITIALIZER;
-
-}  // namespace
-
-// static
-scoped_refptr<ShareableFileReference> ShareableFileReference::Get(
-    const base::FilePath& path) {
-  ShareableFileMap::iterator found = g_file_map.Get().Find(path);
-  ShareableFileReference* reference =
-      (found == g_file_map.Get().End()) ? NULL : found->second;
-  return scoped_refptr<ShareableFileReference>(reference);
-}
-
-// static
-scoped_refptr<ShareableFileReference> ShareableFileReference::GetOrCreate(
-    const base::FilePath& path,
-    FinalReleasePolicy policy,
-    base::TaskRunner* file_task_runner) {
-  return GetOrCreate(
-      ScopedFile(path, static_cast<ScopedFile::ScopeOutPolicy>(policy),
-                 file_task_runner));
-}
-
-// static
-scoped_refptr<ShareableFileReference> ShareableFileReference::GetOrCreate(
-    ScopedFile scoped_file) {
-  if (scoped_file.path().empty())
-    return scoped_refptr<ShareableFileReference>();
-
-  typedef std::pair<ShareableFileMap::iterator, bool> InsertResult;
-  // Required for VS2010:
-  // http://connect.microsoft.com/VisualStudio/feedback/
-  // details/520043/error-converting-from-null-to-a-pointer-type-in-std-pair
-  storage::ShareableFileReference* null_reference = NULL;
-  InsertResult result = g_file_map.Get().Insert(
-      ShareableFileMap::value_type(scoped_file.path(), null_reference));
-  if (result.second == false) {
-    scoped_file.Release();
-    return scoped_refptr<ShareableFileReference>(result.first->second);
-  }
-
-  // Wasn't in the map, create a new reference and store the pointer.
-  scoped_refptr<ShareableFileReference> reference(
-      new ShareableFileReference(scoped_file.Pass()));
-  result.first->second = reference.get();
-  return reference;
-}
-
-void ShareableFileReference::AddFinalReleaseCallback(
-    const FinalReleaseCallback& callback) {
-  DCHECK(g_file_map.Get().CalledOnValidThread());
-  scoped_file_.AddScopeOutCallback(callback, NULL);
-}
-
-ShareableFileReference::ShareableFileReference(ScopedFile scoped_file)
-    : scoped_file_(scoped_file.Pass()) {
-  DCHECK(g_file_map.Get().Find(path())->second == NULL);
-}
-
-ShareableFileReference::~ShareableFileReference() {
-  DCHECK(g_file_map.Get().Find(path())->second == this);
-  g_file_map.Get().Erase(path());
-}
-
-}  // namespace storage