Moving chrome/browser/chromeos/drive/change_list* into components/drive

chrome/browser/chromeos/drive/change_list_loader.h

-// 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.
-
-#ifndef CHROME_BROWSER_CHROMEOS_DRIVE_CHANGE_LIST_LOADER_H_
-#define CHROME_BROWSER_CHROMEOS_DRIVE_CHANGE_LIST_LOADER_H_
-
-#include <string>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/scoped_vector.h"
-#include "base/observer_list.h"
-#include "base/threading/thread_checker.h"
-#include "components/drive/file_errors.h"
-#include "google_apis/drive/drive_api_error_codes.h"
-#include "google_apis/drive/drive_common_callbacks.h"
-
-class GURL;
-
-namespace base {
-class CancellationFlag;
-class ScopedClosureRunner;
-class SequencedTaskRunner;
-class Time;
-}  // namespace base
-
-namespace google_apis {
-class AboutResource;
-}  // namespace google_apis
-
-namespace drive {
-
-class EventLogger;
-class JobScheduler;
-class ResourceEntry;
-
-namespace internal {
-
-class ChangeList;
-class ChangeListLoaderObserver;
-class ChangeListProcessor;
-class DirectoryLoader;
-class ResourceMetadata;
-
-// Delays execution of tasks as long as more than one lock is alive.
-// Used to ensure that ChangeListLoader does not cause race condition by adding
-// new entries created by sync tasks before they do.
-// All code which may add entries found on the server to the local metadata
-// should use this class.
-class LoaderController {
- public:
-  LoaderController();
-  ~LoaderController();
-
-  // Increments the lock count and returns an object which decrements the count
-  // on its destruction.
-  // While the lock count is positive, tasks will be pending.
-  scoped_ptr<base::ScopedClosureRunner> GetLock();
-
-  // Runs the task if the lock count is 0, otherwise it will be pending.
-  void ScheduleRun(const base::Closure& task);
-
- private:
-  // Decrements the lock count.
-  void Unlock();
-
-  int lock_count_;
-  std::vector<base::Closure> pending_tasks_;
-
-  base::ThreadChecker thread_checker_;
-
-  base::WeakPtrFactory<LoaderController> weak_ptr_factory_;
-  DISALLOW_COPY_AND_ASSIGN(LoaderController);
-};
-
-// This class is responsible to load AboutResource from the server and cache it.
-class AboutResourceLoader {
- public:
-  explicit AboutResourceLoader(JobScheduler* scheduler);
-  ~AboutResourceLoader();
-
-  // Returns the cached about resource.
-  // NULL is returned if the cache is not available.
-  const google_apis::AboutResource* cached_about_resource() const {
-    return cached_about_resource_.get();
-  }
-
-  // Gets the 'latest' about resource and asynchronously runs |callback|. I.e.,
-  // 1) If the last call to UpdateAboutResource call is in-flight, wait for it.
-  // 2) Otherwise, if the resource is cached, just returns the cached value.
-  // 3) If neither of the above hold, queries the API server by calling
-  //   |UpdateAboutResource|.
-  void GetAboutResource(const google_apis::AboutResourceCallback& callback);
-
-  // Gets the about resource from the server, and caches it if successful. This
-  // function calls JobScheduler::GetAboutResource internally. The cache will be
-  // used in |GetAboutResource|.
-  void UpdateAboutResource(const google_apis::AboutResourceCallback& callback);
-
- private:
-  // Part of UpdateAboutResource().
-  // This function should be called when the latest about resource is being
-  // fetched from the server. The retrieved about resource is cloned, and one is
-  // cached and the other is passed to callbacks associated with |task_id|.
-  void UpdateAboutResourceAfterGetAbout(
-      int task_id,
-      google_apis::DriveApiErrorCode status,
-      scoped_ptr<google_apis::AboutResource> about_resource);
-
-  JobScheduler* scheduler_;
-  scoped_ptr<google_apis::AboutResource> cached_about_resource_;
-
-  // Identifier to denote the latest UpdateAboutResource call.
-  int current_update_task_id_;
-  // Mapping from each UpdateAboutResource task ID to the corresponding
-  // callbacks. Note that there will be multiple callbacks for a single task
-  // when GetAboutResource is called before the task completes.
-  std::map<int, std::vector<google_apis::AboutResourceCallback> >
-      pending_callbacks_;
-
-  base::ThreadChecker thread_checker_;
-
-  base::WeakPtrFactory<AboutResourceLoader> weak_ptr_factory_;
-  DISALLOW_COPY_AND_ASSIGN(AboutResourceLoader);
-};
-
-// ChangeListLoader is used to load the change list, the full resource list,
-// and directory contents, from Google Drive API.  The class also updates the
-// resource metadata with the change list loaded from the server.
-//
-// Note that the difference between "resource list" and "change list" is
-// subtle hence the two words are often used interchangeably. To be precise,
-// "resource list" refers to metadata from the server when fetching the full
-// resource metadata, or fetching directory contents, whereas "change list"
-// refers to metadata from the server when fetching changes (delta).
-class ChangeListLoader {
- public:
-  // Resource feed fetcher from the server.
-  class FeedFetcher;
-
-  ChangeListLoader(EventLogger* logger,
-                   base::SequencedTaskRunner* blocking_task_runner,
-                   ResourceMetadata* resource_metadata,
-                   JobScheduler* scheduler,
-                   AboutResourceLoader* about_resource_loader,
-                   LoaderController* apply_task_controller);
-  ~ChangeListLoader();
-
-  // Indicates whether there is a request for full resource list or change
-  // list fetching is in flight (i.e. directory contents fetching does not
-  // count).
-  bool IsRefreshing() const;
-
-  // Adds and removes the observer.
-  void AddObserver(ChangeListLoaderObserver* observer);
-  void RemoveObserver(ChangeListLoaderObserver* observer);
-
-  // Checks for updates on the server. Does nothing if the change list is now
-  // being loaded or refreshed. |callback| must not be null.
-  // Note: |callback| will be called if the check for updates actually
-  // runs, i.e. it may NOT be called if the checking is ignored.
-  void CheckForUpdates(const FileOperationCallback& callback);
-
-  // Starts the change list loading if needed. If the locally stored metadata is
-  // available, runs |callback| immediately and starts checking server for
-  // updates in background. If the locally stored metadata is not available,
-  // starts loading from the server, and runs |callback| to tell the result to
-  // the caller when it is finished.
-  //
-  // |callback| must not be null.
-  void LoadIfNeeded(const FileOperationCallback& callback);
-
- private:
-  // Starts the resource metadata loading and calls |callback| when it's done.
-  void Load(const FileOperationCallback& callback);
-  void LoadAfterGetLargestChangestamp(bool is_initial_load,
-                                      const int64* local_changestamp,
-                                      FileError error);
-  void LoadAfterGetAboutResource(
-      int64 local_changestamp,
-      google_apis::DriveApiErrorCode status,
-      scoped_ptr<google_apis::AboutResource> about_resource);
-
-  // Part of Load().
-  // This function should be called when the change list load is complete.
-  // Flushes the callbacks for change list loading and all directory loading.
-  void OnChangeListLoadComplete(FileError error);
-
-  // Called when the loading about_resource_loader_->UpdateAboutResource is
-  // completed.
-  void OnAboutResourceUpdated(google_apis::DriveApiErrorCode error,
-                              scoped_ptr<google_apis::AboutResource> resource);
-
-  // ================= Implementation for change list loading =================
-
-  // Part of LoadFromServerIfNeeded().
-  // Starts loading the change list since |start_changestamp|, or the full
-  // resource list if |start_changestamp| is zero.
-  void LoadChangeListFromServer(int64 start_changestamp);
-
-  // Part of LoadChangeListFromServer().
-  // Called when the entire change list is loaded.
-  void LoadChangeListFromServerAfterLoadChangeList(
-      scoped_ptr<google_apis::AboutResource> about_resource,
-      bool is_delta_update,
-      FileError error,
-      ScopedVector<ChangeList> change_lists);
-
-  // Part of LoadChangeListFromServer().
-  // Called when the resource metadata is updated.
-  void LoadChangeListFromServerAfterUpdate(
-      ChangeListProcessor* change_list_processor,
-      bool should_notify_changed_directories,
-      const base::Time& start_time,
-      FileError error);
-
-  EventLogger* logger_;  // Not owned.
-  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
-  scoped_ptr<base::CancellationFlag> in_shutdown_;
-  ResourceMetadata* resource_metadata_;  // Not owned.
-  JobScheduler* scheduler_;  // Not owned.
-  AboutResourceLoader* about_resource_loader_;  // Not owned.
-  LoaderController* loader_controller_;  // Not owned.
-  base::ObserverList<ChangeListLoaderObserver> observers_;
-  std::vector<FileOperationCallback> pending_load_callback_;
-  FileOperationCallback pending_update_check_callback_;
-
-  // Running feed fetcher.
-  scoped_ptr<FeedFetcher> change_feed_fetcher_;
-
-  // True if the full resource list is loaded (i.e. the resource metadata is
-  // stored locally).
-  bool loaded_;
-
-  base::ThreadChecker thread_checker_;
-
-  // Note: This should remain the last member so it'll be destroyed and
-  // invalidate its weak pointers before any other members are destroyed.
-  base::WeakPtrFactory<ChangeListLoader> weak_ptr_factory_;
-  DISALLOW_COPY_AND_ASSIGN(ChangeListLoader);
-};
-
-}  // namespace internal
-}  // namespace drive
-
-#endif  // CHROME_BROWSER_CHROMEOS_DRIVE_CHANGE_LIST_LOADER_H_