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