components/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 COMPONENTS_DRIVE_FILE_CACHE_H_
   6 #define COMPONENTS_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 "base/threading/thread_checker.h"
  16 #include "components/drive/file_errors.h"
  17 #include "components/drive/resource_metadata_storage.h"
  18
  19 namespace base {
  20 class ScopedClosureRunner;
  21 class SequencedTaskRunner;
  22 }  // namespace base
  23
  24 namespace drive {
  25
  26 namespace internal {
  27
  28 // Interface class used for getting the free disk space. Tests can inject an
  29 // implementation that reports fake free disk space.
  30 class FreeDiskSpaceGetterInterface {
  31  public:
  32   virtual ~FreeDiskSpaceGetterInterface() {}
  33   virtual int64 AmountOfFreeDiskSpace() = 0;
  34 };
  35
  36 // FileCache is used to maintain cache states of FileSystem.
  37 //
  38 // All non-static public member functions, unless mentioned otherwise (see
  39 // GetCacheFilePath() for example), should be run with |blocking_task_runner|.
  40 class FileCache {
  41  public:
  42   // Enum defining type of file operation e.g. copy or move, etc.
  43   enum FileOperationType {
  44     FILE_OPERATION_MOVE = 0,
  45     FILE_OPERATION_COPY,
  46   };
  47
  48   // |cache_file_directory| stores cached files.
  49   //
  50   // |blocking_task_runner| indicates the blocking worker pool for cache
  51   // operations. All operations on this FileCache must be run on this runner.
  52   // Must not be null.
  53   //
  54   // |free_disk_space_getter| is used to inject a custom free disk space
  55   // getter for testing. NULL must be passed for production code.
  56   //
  57   // Must be called on the UI thread.
  58   FileCache(ResourceMetadataStorage* storage,
  59             const base::FilePath& cache_file_directory,
  60             base::SequencedTaskRunner* blocking_task_runner,
  61             FreeDiskSpaceGetterInterface* free_disk_space_getter);
  62
  63   // Returns true if the given path is under drive cache directory, i.e.
  64   // <user_profile_dir>/GCache/v1
  65   //
  66   // Can be called on any thread.
  67   bool IsUnderFileCacheDirectory(const base::FilePath& path) const;
  68
  69   // Frees up disk space to store a file with |num_bytes| size content, while
  70   // keeping cryptohome::kMinFreeSpaceInBytes bytes on the disk, if needed.
  71   // Returns true if we successfully manage to have enough space, otherwise
  72   // false.
  73   bool FreeDiskSpaceIfNeededFor(int64 num_bytes);
  74
  75   // Checks if file corresponding to |id| exists in cache, and returns
  76   // FILE_ERROR_OK with |cache_file_path| storing the path to the file.
  77   // |cache_file_path| must not be null.
  78   FileError GetFile(const std::string& id, base::FilePath* cache_file_path);
  79
  80   // Stores |source_path| as a cache of the remote content of the file
  81   // with |id| and |md5|.
  82   // Pass an empty string as MD5 to mark the entry as dirty.
  83   FileError Store(const std::string& id,
  84                   const std::string& md5,
  85                   const base::FilePath& source_path,
  86                   FileOperationType file_operation_type);
  87
  88   // Pins the specified entry.
  89   FileError Pin(const std::string& id);
  90
  91   // Unpins the specified entry.
  92   FileError Unpin(const std::string& id);
  93
  94   // Sets the state of the cache entry corresponding to |id| as mounted.
  95   FileError MarkAsMounted(const std::string& id,
  96                           base::FilePath* cache_file_path);
  97
  98   // Sets the state of the cache entry corresponding to file_path as unmounted.
  99   FileError MarkAsUnmounted(const base::FilePath& file_path);
 100
 101   // Opens the cache file corresponding to |id| for write. |file_closer| should
 102   // be kept alive until writing finishes.
 103   // This method must be called before writing to cache files.
 104   FileError OpenForWrite(const std::string& id,
 105                          scoped_ptr<base::ScopedClosureRunner>* file_closer);
 106
 107   // Returns true if the cache file corresponding to |id| is write-opened.
 108   bool IsOpenedForWrite(const std::string& id);
 109
 110   // Calculates MD5 of the cache file and updates the stored value.
 111   FileError UpdateMd5(const std::string& id);
 112
 113   // Clears dirty state of the specified entry.
 114   FileError ClearDirty(const std::string& id);
 115
 116   // Removes the specified cache entry and delete cache files if available.
 117   FileError Remove(const std::string& id);
 118
 119   // Removes all the files in the cache directory.
 120   bool ClearAll();
 121
 122   // Initializes the cache. Returns true on success.
 123   bool Initialize();
 124
 125   // Destroys this cache. This function posts a task to the blocking task
 126   // runner to safely delete the object.
 127   // Must be called on the UI thread.
 128   void Destroy();
 129
 130   // Moves files in the cache directory which are not managed by FileCache to
 131   // |dest_directory|.
 132   // |recovered_cache_info| should contain cache info recovered from the trashed
 133   // metadata DB. It is used to ignore non-dirty files.
 134   bool RecoverFilesFromCacheDirectory(
 135       const base::FilePath& dest_directory,
 136       const ResourceMetadataStorage::RecoveredCacheInfoMap&
 137           recovered_cache_info);
 138
 139  private:
 140   friend class FileCacheTest;
 141
 142   ~FileCache();
 143
 144   // Returns absolute path of the file if it were cached or to be cached.
 145   //
 146   // Can be called on any thread.
 147   base::FilePath GetCacheFilePath(const std::string& id) const;
 148
 149   // Checks whether the current thread is on the right sequenced worker pool
 150   // with the right sequence ID. If not, DCHECK will fail.
 151   void AssertOnSequencedWorkerPool();
 152
 153   // Destroys the cache on the blocking pool.
 154   void DestroyOnBlockingPool();
 155
 156   // Returns true if we have sufficient space to store the given number of
 157   // bytes, while keeping cryptohome::kMinFreeSpaceInBytes bytes on the disk.
 158   bool HasEnoughSpaceFor(int64 num_bytes, const base::FilePath& path);
 159
 160   // Renames cache files from old "prefix:id.md5" format to the new format.
 161   // TODO(hashimoto): Remove this method at some point.
 162   bool RenameCacheFilesToNewFormat();
 163
 164   // This method must be called after writing to a cache file.
 165   // Used to implement OpenForWrite().
 166   void CloseForWrite(const std::string& id);
 167
 168   const base::FilePath cache_file_directory_;
 169
 170   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 171
 172   base::CancellationFlag in_shutdown_;
 173
 174   ResourceMetadataStorage* storage_;
 175
 176   FreeDiskSpaceGetterInterface* free_disk_space_getter_;  // Not owned.
 177
 178   // IDs of files being write-opened.
 179   std::map<std::string, int> write_opened_files_;
 180
 181   // IDs of files marked mounted.
 182   std::set<std::string> mounted_files_;
 183
 184   base::ThreadChecker thread_checker_;
 185
 186   // Note: This should remain the last member so it'll be destroyed and
 187   // invalidate its weak pointers before any other members are destroyed.
 188   // This object should be accessed only on |blocking_task_runner_|.
 189   base::WeakPtrFactory<FileCache> weak_ptr_factory_;
 190   DISALLOW_COPY_AND_ASSIGN(FileCache);
 191 };
 192
 193 }  // namespace internal
 194 }  // namespace drive
 195
 196 #endif  // COMPONENTS_DRIVE_FILE_CACHE_H_