chrome/browser/chromeos/drive/file_cache.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_FILE_CACHE_H_
#define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_H_

#include <string>
#include <vector>

#include "base/callback_forward.h"
#include "base/files/file_path.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "chrome/browser/chromeos/drive/file_cache_metadata.h"
#include "chrome/browser/chromeos/drive/file_errors.h"

class Profile;

namespace base {

class SequencedTaskRunner;

}  // namespace base

namespace drive {

class FileCacheEntry;

// Callback for GetCacheEntry.
// |success| indicates if the operation was successful.
// |cache_entry| is the obtained cache entry. On failure, |cache_state| is
// set to TEST_CACHE_STATE_NONE.
typedef base::Callback<void(bool success, const FileCacheEntry& cache_entry)>
    GetCacheEntryCallback;

namespace internal {

class FileCacheMetadata;
class FileCacheObserver;

// Callback for GetFileFromCache.
typedef base::Callback<void(FileError error,
                            const base::FilePath& cache_file_path)>
    GetFileFromCacheCallback;

// Callback for RequestInitialize.
// |success| indicates if the operation was successful.
// TODO(satorux): Change this to FileError when it becomes necessary.
typedef base::Callback<void(bool success)>
    InitializeCacheCallback;

// Interface class used for getting the free disk space. Tests can inject an
// implementation that reports fake free disk space.
class FreeDiskSpaceGetterInterface {
 public:
  virtual ~FreeDiskSpaceGetterInterface() {}
  virtual int64 AmountOfFreeDiskSpace() = 0;
};

// FileCache is used to maintain cache states of FileSystem.
//
// All non-static public member functions, unless mentioned otherwise (see
// GetCacheFilePath() for example), should be run with |blocking_task_runner|.
class FileCache {
 public:
  // Enum defining GCache subdirectory location.
  // This indexes into |FileCache::cache_paths_| vector.
  enum CacheSubDirectoryType {
    CACHE_TYPE_META = 0,       // Downloaded feeds.
    CACHE_TYPE_PERSISTENT,     // Files that are pinned or modified locally,
                               // not evictable, hopefully.
    CACHE_TYPE_TMP,            // Files that don't meet criteria to be in
                               // persistent dir, and hence evictable.
    CACHE_TYPE_TMP_DOWNLOADS,  // Downloaded files.
    CACHE_TYPE_TMP_DOCUMENTS,  // Temporary JSON files for hosted documents.
    NUM_CACHE_TYPES,           // This must be at the end.
  };

  // Enum defining type of file operation e.g. copy or move, etc.
  enum FileOperationType {
    FILE_OPERATION_MOVE = 0,
    FILE_OPERATION_COPY,
  };

  // |cache_root_path| specifies the root directory for the cache. Sub
  // directories will be created under the root directory.
  //
  // |blocking_task_runner| is used to post a task to the blocking worker
  // pool for file operations. Must not be null.
  //
  // |free_disk_space_getter| is used to inject a custom free disk space
  // getter for testing. NULL must be passed for production code.
  //
  // Must be called on the UI thread.
  FileCache(const base::FilePath& cache_root_path,
            base::SequencedTaskRunner* blocking_task_runner,
            FreeDiskSpaceGetterInterface* free_disk_space_getter);

  // Returns the sub-directory under drive cache directory for the given sub
  // directory type. Example:  <user_profile_dir>/GCache/v1/tmp
  //
  // Can be called on any thread.
  base::FilePath GetCacheDirectoryPath(
      CacheSubDirectoryType sub_dir_type) const;

  // Returns true if the given path is under drive cache directory, i.e.
  // <user_profile_dir>/GCache/v1
  //
  // Can be called on any thread.
  bool IsUnderFileCacheDirectory(const base::FilePath& path) const;

  // Adds observer.
  // Must be called on the UI thread.
  void AddObserver(FileCacheObserver* observer);

  // Removes observer.
  // Must be called on the UI thread.
  void RemoveObserver(FileCacheObserver* observer);

  // Gets the cache entry for file corresponding to |resource_id| and |md5|
  // and runs |callback| with true and the entry found if entry exists in cache
  // map.  Otherwise, runs |callback| with false.
  // |md5| can be empty if only matching |resource_id| is desired.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void GetCacheEntryOnUIThread(const std::string& resource_id,
                               const std::string& md5,
                               const GetCacheEntryCallback& callback);

  // Gets the cache entry by the given resource ID and MD5.
  // See also GetCacheEntryOnUIThread().
  bool GetCacheEntry(const std::string& resource_id,
                     const std::string& md5,
                     FileCacheEntry* entry);

  // Runs Iterate() with |iteration_callback| on |blocking_task_runner_| and
  // runs |completion_callback| upon completion.
  // Must be called on UI thread.
  void IterateOnUIThread(const CacheIterateCallback& iteration_callback,
                         const base::Closure& completion_callback);

  // Iterates all files in the cache and calls |iteration_callback| for each
  // file. |completion_callback| is run upon completion.
  // TODO(hashimoto): Stop using callbacks for this method. crbug.com/242818
  void Iterate(const CacheIterateCallback& iteration_callback);


  // Runs FreeDiskSpaceIfNeededFor() on |blocking_task_runner_|, and calls
  // |callback| with the result asynchronously.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void FreeDiskSpaceIfNeededForOnUIThread(
      int64 num_bytes,
      const InitializeCacheCallback& callback);

  // Frees up disk space to store a file with |num_bytes| size content, while
  // keeping kMinFreeSpace bytes on the disk, if needed.
  // Returns true if we successfully manage to have enough space, otherwise
  // false.
  bool FreeDiskSpaceIfNeededFor(int64 num_bytes);

  // Runs GetFile() on |blocking_task_runner_|, and calls |callback| with
  // the result asynchronously.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void GetFileOnUIThread(const std::string& resource_id,
                         const std::string& md5,
                         const GetFileFromCacheCallback& callback);

  // Checks if file corresponding to |resource_id| and |md5| exists in cache,
  // and returns FILE_ERROR_OK with |cache_file_path| storing the path to
  // the file.
  // |cache_file_path| must not be null.
  FileError GetFile(const std::string& resource_id,
                    const std::string& md5,
                    base::FilePath* cache_file_path);

  // Runs Store() on |blocking_task_runner_|, and calls |callback| with
  // the result asynchronously.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void StoreOnUIThread(const std::string& resource_id,
                       const std::string& md5,
                       const base::FilePath& source_path,
                       FileOperationType file_operation_type,
                       const FileOperationCallback& callback);

  // Stores |source_path| as a cache of the remote content of the file
  // with |resource_id| and |md5|.
  FileError Store(const std::string& resource_Id,
                  const std::string& md5,
                  const base::FilePath& source_path,
                  FileOperationType file_operation_type);

  // Stores |source_path| to the cache and mark it as dirty, i.e., needs to be
  // uploaded to the remove server for syncing.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void StoreLocallyModifiedOnUIThread(const std::string& resource_id,
                                      const std::string& md5,
                                      const base::FilePath& source_path,
                                      FileOperationType file_operation_type,
                                      const FileOperationCallback& callback);

  // Pins the specified entry.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void PinOnUIThread(const std::string& resource_id,
                     const std::string& md5,
                     const FileOperationCallback& callback);

  // Runs Unpin() on |blocking_task_runner_|, and calls |callback| with the
  // result asynchronously.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void UnpinOnUIThread(const std::string& resource_id,
                       const std::string& md5,
                       const FileOperationCallback& callback);

  // Unpins the specified entry.
  FileError Unpin(const std::string& resource_id, const std::string& md5);

  // Sets the state of the cache entry corresponding to |resource_id| and |md5|
  // as mounted.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void MarkAsMountedOnUIThread(const std::string& resource_id,
                               const std::string& md5,
                               const GetFileFromCacheCallback& callback);

  // Set the state of the cache entry corresponding to file_path as unmounted.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void MarkAsUnmountedOnUIThread(const base::FilePath& file_path,
                                 const FileOperationCallback& callback);

  // Marks the specified entry dirty.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void MarkDirtyOnUIThread(const std::string& resource_id,
                           const std::string& md5,
                           const FileOperationCallback& callback);

  // Commits changes for the specified dirty entry.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void CommitDirtyOnUIThread(const std::string& resource_id,
                             const std::string& md5,
                             const FileOperationCallback& callback);

  // Clears dirty state of the specified entry.
  FileError ClearDirty(const std::string& resource_id,
                       const std::string& md5);

  // Runs Remove() on |blocking_task_runner_| and runs |callback| with the
  // result.
  // Must be called on the UI thread.
  void RemoveOnUIThread(const std::string& resource_id,
                        const FileOperationCallback& callback);

  // Removes the specified cache entry and delete cache files if available.
  // Synchronous version of RemoveOnUIThread().
  FileError Remove(const std::string& resource_id);

  // Does the following:
  // - remove all the files in the cache directory.
  // - re-create the |metadata_| instance.
  // |callback| must not be null.
  // Must be called on the UI thread.
  void ClearAllOnUIThread(const InitializeCacheCallback& callback);

  // Utility method to call Initialize on UI thread. |callback| is called on
  // UI thread when the initialization is complete.
  // |callback| must not be null.
  void RequestInitialize(const InitializeCacheCallback& callback);

  // Utility method to call InitializeForTesting on UI thread.
  void RequestInitializeForTesting();

  // Destroys this cache. This function posts a task to the blocking task
  // runner to safely delete the object.
  // Must be called on the UI thread.
  void Destroy();

  // Returns file paths for all the cache sub directories under
  // |cache_root_path|.
  static std::vector<base::FilePath> GetCachePaths(
      const base::FilePath& cache_root_path);

  // Creates cache directory and its sub-directories if they don't exist.
  // TODO(glotov): take care of this when the setup and cleanup part is
  // landed, noting that these directories need to be created for development
  // in linux box and unittest. (http://crosbug.com/27577)
  static bool CreateCacheDirectories(
      const std::vector<base::FilePath>& paths_to_create);

  // Returns the type of the sub directory where the cache file is stored.
  static CacheSubDirectoryType GetSubDirectoryType(
      const FileCacheEntry& cache_entry);

 private:
  friend class FileCacheTest;

  // Enum defining origin of a cached file.
  enum CachedFileOrigin {
    CACHED_FILE_FROM_SERVER = 0,
    CACHED_FILE_LOCALLY_MODIFIED,
    CACHED_FILE_MOUNTED,
  };

  ~FileCache();

  // Returns absolute path of the file if it were cached or to be cached.
  //
  // Can be called on any thread.
  base::FilePath GetCacheFilePath(const std::string& resource_id,
                                  const std::string& md5,
                                  CacheSubDirectoryType sub_dir_type,
                                  CachedFileOrigin file_origin) const;


  // Checks whether the current thread is on the right sequenced worker pool
  // with the right sequence ID. If not, DCHECK will fail.
  void AssertOnSequencedWorkerPool();

  // Initializes the cache. Returns true on success.
  bool InitializeOnBlockingPool();

  // Initializes the cache with in-memory cache for testing.
  // The in-memory cache is used since it's faster than the db.
  void InitializeOnBlockingPoolForTesting();

  // Destroys the cache on the blocking pool.
  void DestroyOnBlockingPool();

  // Used to implement Store and StoreLocallyModifiedOnUIThread.
  // TODO(hidehiko): Merge this method with Store(), after
  // StoreLocallyModifiedOnUIThread is removed.
  FileError StoreInternal(const std::string& resource_id,
                          const std::string& md5,
                          const base::FilePath& source_path,
                          FileOperationType file_operation_type,
                          CachedFileOrigin origin);

  // Used to implement PinOnUIThread.
  FileError Pin(const std::string& resource_id,
                const std::string& md5);

  // Used to implement MarkAsMountedOnUIThread.
  FileError MarkAsMounted(const std::string& resource_id,
                          const std::string& md5,
                          base::FilePath* cache_file_path);

  // Used to implement MarkAsUnmountedOnUIThread.
  FileError MarkAsUnmounted(const base::FilePath& file_path);

  // Used to implement MarkDirtyOnUIThread.
  FileError MarkDirty(const std::string& resource_id,
                      const std::string& md5);

  // Used to implement ClearAllOnUIThread.
  bool ClearAll();

  // Runs callback and notifies the observers when file is pinned.
  void OnPinned(const std::string& resource_id,
                const std::string& md5,
                const FileOperationCallback& callback,
                FileError error);

  // Runs callback and notifies the observers when file is unpinned.
  void OnUnpinned(const std::string& resource_id,
                  const std::string& md5,
                  const FileOperationCallback& callback,
                  FileError error);

  // Runs callback and notifies the observers when file is committed.
  void OnCommitDirty(const std::string& resource_id,
                     const FileOperationCallback& callback,
                     FileError error);

  // Returns true if we have sufficient space to store the given number of
  // bytes, while keeping kMinFreeSpace bytes on the disk.
  bool HasEnoughSpaceFor(int64 num_bytes, const base::FilePath& path);

  // The root directory of the cache (i.e. <user_profile_dir>/GCache/v1).
  const base::FilePath cache_root_path_;
  // Paths for all subdirectories of GCache, one for each
  // FileCache::CacheSubDirectoryType enum.
  const std::vector<base::FilePath> cache_paths_;
  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;

  // The cache state data. This member must be access only on the blocking pool.
  scoped_ptr<FileCacheMetadata> metadata_;

  // List of observers, this member must be accessed on UI thread.
  ObserverList<FileCacheObserver> observers_;

  FreeDiskSpaceGetterInterface* free_disk_space_getter_;  // Not owned.

  // 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<FileCache> weak_ptr_factory_;
  DISALLOW_COPY_AND_ASSIGN(FileCache);
};

// The minimum free space to keep. FileSystem::GetFileByPath() returns
// GDATA_FILE_ERROR_NO_SPACE if the available space is smaller than
// this value.
//
// Copied from cryptohome/homedirs.h.
// TODO(satorux): Share the constant.
const int64 kMinFreeSpace = 512 * 1LL << 20;

}  // namespace internal
}  // namespace drive

#endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_H_