chrome/browser/chromeos/drive/file_cache.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_H_
   6 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_H_
   7
   8 #include <set>
   9 #include <string>
  10
  11 #include "base/files/file_path.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/memory/weak_ptr.h"
  14 #include "base/synchronization/cancellation_flag.h"
  15 #include "chrome/browser/chromeos/drive/file_errors.h"
  16 #include "chrome/browser/chromeos/drive/resource_metadata_storage.h"
  17
  18 namespace base {
  19 class ScopedClosureRunner;
  20 class SequencedTaskRunner;
  21 }  // namespace base
  22
  23 namespace drive {
  24
  25 namespace internal {
  26
  27 // Interface class used for getting the free disk space. Tests can inject an
  28 // implementation that reports fake free disk space.
  29 class FreeDiskSpaceGetterInterface {
  30  public:
  31   virtual ~FreeDiskSpaceGetterInterface() {}
  32   virtual int64 AmountOfFreeDiskSpace() = 0;
  33 };
  34
  35 // FileCache is used to maintain cache states of FileSystem.
  36 //
  37 // All non-static public member functions, unless mentioned otherwise (see
  38 // GetCacheFilePath() for example), should be run with |blocking_task_runner|.
  39 class FileCache {
  40  public:
  41   // Enum defining type of file operation e.g. copy or move, etc.
  42   enum FileOperationType {
  43     FILE_OPERATION_MOVE = 0,
  44     FILE_OPERATION_COPY,
  45   };
  46
  47   // |cache_file_directory| stores cached files.
  48   //
  49   // |blocking_task_runner| indicates the blocking worker pool for cache
  50   // operations. All operations on this FileCache must be run on this runner.
  51   // Must not be null.
  52   //
  53   // |free_disk_space_getter| is used to inject a custom free disk space
  54   // getter for testing. NULL must be passed for production code.
  55   //
  56   // Must be called on the UI thread.
  57   FileCache(ResourceMetadataStorage* storage,
  58             const base::FilePath& cache_file_directory,
  59             base::SequencedTaskRunner* blocking_task_runner,
  60             FreeDiskSpaceGetterInterface* free_disk_space_getter);
  61
  62   // Returns true if the given path is under drive cache directory, i.e.
  63   // <user_profile_dir>/GCache/v1
  64   //
  65   // Can be called on any thread.
  66   bool IsUnderFileCacheDirectory(const base::FilePath& path) const;
  67
  68   // Frees up disk space to store a file with |num_bytes| size content, while
  69   // keeping cryptohome::kMinFreeSpaceInBytes bytes on the disk, if needed.
  70   // Returns true if we successfully manage to have enough space, otherwise
  71   // false.
  72   bool FreeDiskSpaceIfNeededFor(int64 num_bytes);
  73
  74   // Checks if file corresponding to |id| exists in cache, and returns
  75   // FILE_ERROR_OK with |cache_file_path| storing the path to the file.
  76   // |cache_file_path| must not be null.
  77   FileError GetFile(const std::string& id, base::FilePath* cache_file_path);
  78
  79   // Stores |source_path| as a cache of the remote content of the file
  80   // with |id| and |md5|.
  81   // Pass an empty string as MD5 to mark the entry as dirty.
  82   FileError Store(const std::string& id,
  83                   const std::string& md5,
  84                   const base::FilePath& source_path,
  85                   FileOperationType file_operation_type);
  86
  87   // Pins the specified entry.
  88   FileError Pin(const std::string& id);
  89
  90   // Unpins the specified entry.
  91   FileError Unpin(const std::string& id);
  92
  93   // Sets the state of the cache entry corresponding to |id| as mounted.
  94   FileError MarkAsMounted(const std::string& id,
  95                           base::FilePath* cache_file_path);
  96
  97   // Sets the state of the cache entry corresponding to file_path as unmounted.
  98   FileError MarkAsUnmounted(const base::FilePath& file_path);
  99
 100   // Opens the cache file corresponding to |id| for write. |file_closer| should
 101   // be kept alive until writing finishes.
 102   // This method must be called before writing to cache files.
 103   FileError OpenForWrite(const std::string& id,
 104                          scoped_ptr<base::ScopedClosureRunner>* file_closer);
 105
 106   // Returns true if the cache file corresponding to |id| is write-opened.
 107   bool IsOpenedForWrite(const std::string& id);
 108
 109   // Calculates MD5 of the cache file and updates the stored value.
 110   FileError UpdateMd5(const std::string& id);
 111
 112   // Clears dirty state of the specified entry.
 113   FileError ClearDirty(const std::string& id);
 114
 115   // Removes the specified cache entry and delete cache files if available.
 116   FileError Remove(const std::string& id);
 117
 118   // Removes all the files in the cache directory.
 119   bool ClearAll();
 120
 121   // Initializes the cache. Returns true on success.
 122   bool Initialize();
 123
 124   // Destroys this cache. This function posts a task to the blocking task
 125   // runner to safely delete the object.
 126   // Must be called on the UI thread.
 127   void Destroy();
 128
 129   // Moves files in the cache directory which are not managed by FileCache to
 130   // |dest_directory|.
 131   // |recovered_cache_info| should contain cache info recovered from the trashed
 132   // metadata DB. It is used to ignore non-dirty files.
 133   bool RecoverFilesFromCacheDirectory(
 134       const base::FilePath& dest_directory,
 135       const ResourceMetadataStorage::RecoveredCacheInfoMap&
 136           recovered_cache_info);
 137
 138  private:
 139   friend class FileCacheTest;
 140
 141   ~FileCache();
 142
 143   // Returns absolute path of the file if it were cached or to be cached.
 144   //
 145   // Can be called on any thread.
 146   base::FilePath GetCacheFilePath(const std::string& id) const;
 147
 148   // Checks whether the current thread is on the right sequenced worker pool
 149   // with the right sequence ID. If not, DCHECK will fail.
 150   void AssertOnSequencedWorkerPool();
 151
 152   // Destroys the cache on the blocking pool.
 153   void DestroyOnBlockingPool();
 154
 155   // Returns true if we have sufficient space to store the given number of
 156   // bytes, while keeping cryptohome::kMinFreeSpaceInBytes bytes on the disk.
 157   bool HasEnoughSpaceFor(int64 num_bytes, const base::FilePath& path);
 158
 159   // Renames cache files from old "prefix:id.md5" format to the new format.
 160   // TODO(hashimoto): Remove this method at some point.
 161   bool RenameCacheFilesToNewFormat();
 162
 163   // This method must be called after writing to a cache file.
 164   // Used to implement OpenForWrite().
 165   void CloseForWrite(const std::string& id);
 166
 167   const base::FilePath cache_file_directory_;
 168
 169   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 170
 171   base::CancellationFlag in_shutdown_;
 172
 173   ResourceMetadataStorage* storage_;
 174
 175   FreeDiskSpaceGetterInterface* free_disk_space_getter_;  // Not owned.
 176
 177   // IDs of files being write-opened.
 178   std::map<std::string, int> write_opened_files_;
 179
 180   // IDs of files marked mounted.
 181   std::set<std::string> mounted_files_;
 182
 183   // Note: This should remain the last member so it'll be destroyed and
 184   // invalidate its weak pointers before any other members are destroyed.
 185   // This object should be accessed only on |blocking_task_runner_|.
 186   base::WeakPtrFactory<FileCache> weak_ptr_factory_;
 187   DISALLOW_COPY_AND_ASSIGN(FileCache);
 188 };
 189
 190 }  // namespace internal
 191 }  // namespace drive
 192
 193 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_H_