Disk cache: Introduce BlockBitmaps for V3.

net/disk_cache/v3/block_bitmaps.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.
 
 // See net/disk_cache/disk_cache.h for the public interface.
 
-#ifndef NET_DISK_CACHE_BLOCK_FILES_H_
-#define NET_DISK_CACHE_BLOCK_FILES_H_
-
-#include <vector>
+#ifndef NET_DISK_CACHE_V3_BLOCK_BITMAPS_H_
+#define NET_DISK_CACHE_V3_BLOCK_BITMAPS_H_
 
 #include "base/files/file_path.h"
-#include "base/gtest_prod_util.h"
-#include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
 #include "net/disk_cache/addr.h"
-#include "net/disk_cache/mapped_file.h"
+#include "net/disk_cache/block_files.h"
 
 namespace disk_cache {
 
-// This class handles the set of block-files open by the disk cache.
-class NET_EXPORT_PRIVATE BlockFiles {
+class BackendImplV3;
+
+// This class is the interface in the v3 disk cache to the set of files holding
+// cached data that is small enough to not be efficiently stored in a dedicated
+// file (i.e. < kMaxBlockSize). It is primarily used to allocate and free
+// regions in those files used to store data.
+class NET_EXPORT_PRIVATE BlockBitmaps {
  public:
-  explicit BlockFiles(const base::FilePath& path);
-  ~BlockFiles();
+  BlockBitmaps();
+  ~BlockBitmaps();
 
-  // Performs the object initialization. create_files indicates if the backing
-  // files should be created or just open.
-  bool Init(bool create_files);
+  void Init(const BlockFilesBitmaps& bitmaps);
 
   // Creates a new entry on a block file. block_type indicates the size of block
   // to be used (as defined on cache_addr.h), block_count is the number of
   // blocks to allocate, and block_address is the address of the new entry.
   bool CreateBlock(FileType block_type, int block_count, Addr* block_address);
 
-  // Removes an entry from the block files. If deep is true, the storage is zero
-  // filled; otherwise the entry is removed but the data is not altered (must be
-  // already zeroed).
-  void DeleteBlock(Addr address, bool deep);
+  // Removes an entry from the block files.
+  void DeleteBlock(Addr address);
 
-  // Close all the files and set the internal state to be initializad again. The
-  // cache is being purged.
-  void CloseFiles();
+  // Releases the internal bitmaps. The cache is being purged.
+  void Clear();
 
   // Sends UMA stats.
   void ReportStats();
 
   // Returns true if the blocks pointed by a given address are currently used.
   // This method is only intended for debugging.
   bool IsValid(Addr address);
 
  private:
-  // Returns the file that stores a given address.
-  MappedFile* GetFile(Addr address);
+  // Returns the header number that stores a given address.
+  int GetHeaderNumber(Addr address);
 
-  // Attemp to grow this file. Fails if the file cannot be extended anymore.
-  bool GrowBlockFile(MappedFile* file, BlockFileHeader* header);
-
-  // Returns the appropriate file to use for a new block.
-  MappedFile* FileForNewBlock(FileType block_type, int block_count);
-
-  // Restores the header of a potentially inconsistent file.
-  bool FixBlockFileHeader(MappedFile* file);
+  // Returns the appropriate header to use for a new block.
+  int HeaderNumberForNewBlock(FileType block_type, int block_count);
 
   // Retrieves stats for the given file index.
   void GetFileStats(int index, int* used_count, int* load);
 
-  bool init_;
+  BlockFilesBitmaps bitmaps_;
 
-  DISALLOW_COPY_AND_ASSIGN(BlockFiles);
+  DISALLOW_COPY_AND_ASSIGN(BlockBitmaps);
 };
 
 }  // namespace disk_cache
 
-#endif  // NET_DISK_CACHE_BLOCK_FILES_H_
+#endif  // NET_DISK_CACHE_V3_BLOCK_BITMAPS_H_