Disk cache: Reference CL for the implementation of file format version 3.

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_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/block_files.h"
+#include "net/disk_cache/mapped_file.h"
+
+namespace disk_cache {
+
+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 BlockBitmaps(BackendImplV3* backend);
+  ~BlockBitmaps();
+
+  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.
+  void DeleteBlock(Addr address);
+
+  // 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 header number that stores a given address.
+  int GetHeaderNumber(Addr address);
+
+  // Returns the number of entry blocks for the given file type.
+  int EmptyBlocksForType(int first_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);
+
+  BlockFilesBitmaps bitmaps_;
+  BackendImplV3* backend_;
+  int empty_counts_[kFirstAdditionalBlockFileV3];
+
+  DISALLOW_COPY_AND_ASSIGN(BlockBitmaps);
+};
+
+}  // namespace disk_cache
+
+#endif  // NET_DISK_CACHE_V3_BLOCK_BITMAPS_H_