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 // See net/disk_cache/disk_cache.h for the public interface. 6 7 #ifndef NET_DISK_CACHE_BLOCKFILE_BLOCK_FILES_H_ 8 #define NET_DISK_CACHE_BLOCKFILE_BLOCK_FILES_H_ 9 10 #include <vector> 11 12 #include "base/files/file_path.h" 13 #include "base/gtest_prod_util.h" 14 #include "base/memory/scoped_ptr.h" 15 #include "net/base/net_export.h" 16 #include "net/disk_cache/blockfile/addr.h" 17 #include "net/disk_cache/blockfile/disk_format_base.h" 18 #include "net/disk_cache/blockfile/mapped_file.h" 19 20 namespace base { 21 class ThreadChecker; 22 } 23 24 namespace disk_cache { 25 26 // An instance of this class represents the header of a block file in memory. 27 // Note that this class doesn't perform any file operation (as in it only deals 28 // with entities in memory). 29 // The header of a block file (and hence, this object) is all that is needed to 30 // perform common operations like allocating or releasing space for storage; 31 // actual access to that storage, however, is not performed through this class. 32 class NET_EXPORT_PRIVATE BlockHeader { 33 public: 34 BlockHeader(); 35 explicit BlockHeader(BlockFileHeader* header); 36 explicit BlockHeader(MappedFile* file); 37 BlockHeader(const BlockHeader& other); 38 ~BlockHeader(); 39 40 // Creates a new entry of |size| blocks on the allocation map, updating the 41 // apropriate counters. 42 bool CreateMapBlock(int size, int* index); 43 44 // Deletes the block pointed by |index|. 45 void DeleteMapBlock(int index, int block_size); 46 47 // Returns true if the specified block is used. 48 bool UsedMapBlock(int index, int size); 49 50 // Restores the "empty counters" and allocation hints. 51 void FixAllocationCounters(); 52 53 // Returns true if the current block file should not be used as-is to store 54 // more records. |block_count| is the number of blocks to allocate. 55 bool NeedToGrowBlockFile(int block_count) const; 56 57 // Returns true if this block file can be used to store an extra record of 58 // size |block_count|. 59 bool CanAllocate(int block_count) const; 60 61 // Returns the number of empty blocks for this file. 62 int EmptyBlocks() const; 63 64 // Returns the minumum number of allocations that can be satisfied. 65 int MinimumAllocations() const; 66 67 // Returns the number of blocks that this file can store. 68 int Capacity() const; 69 70 // Returns true if the counters look OK. 71 bool ValidateCounters() const; 72 73 // Returns the identifiers of this and the next file (0 if there is none). 74 int FileId() const; 75 int NextFileId() const; 76 77 // Returns the size of the wrapped structure (BlockFileHeader). 78 int Size() const; 79 80 // Returns a pointer to the underlying BlockFileHeader. 81 // TODO(rvargas): This may be removed with the support for V2. 82 BlockFileHeader* Header(); 83 84 private: 85 BlockFileHeader* header_; 86 }; 87 88 typedef std::vector<BlockHeader> BlockFilesBitmaps; 89 90 // This class handles the set of block-files open by the disk cache. 91 class NET_EXPORT_PRIVATE BlockFiles { 92 public: 93 explicit BlockFiles(const base::FilePath& path); 94 ~BlockFiles(); 95 96 // Performs the object initialization. create_files indicates if the backing 97 // files should be created or just open. 98 bool Init(bool create_files); 99 100 // Returns the file that stores a given address. 101 MappedFile* GetFile(Addr address); 102 103 // Creates a new entry on a block file. block_type indicates the size of block 104 // to be used (as defined on cache_addr.h), block_count is the number of 105 // blocks to allocate, and block_address is the address of the new entry. 106 bool CreateBlock(FileType block_type, int block_count, Addr* block_address); 107 108 // Removes an entry from the block files. If deep is true, the storage is zero 109 // filled; otherwise the entry is removed but the data is not altered (must be 110 // already zeroed). 111 void DeleteBlock(Addr address, bool deep); 112 113 // Close all the files and set the internal state to be initializad again. The 114 // cache is being purged. 115 void CloseFiles(); 116 117 // Sends UMA stats. 118 void ReportStats(); 119 120 // Returns true if the blocks pointed by a given address are currently used. 121 // This method is only intended for debugging. 122 bool IsValid(Addr address); 123 124 private: 125 // Set force to true to overwrite the file if it exists. 126 bool CreateBlockFile(int index, FileType file_type, bool force); 127 bool OpenBlockFile(int index); 128 129 // Attemp to grow this file. Fails if the file cannot be extended anymore. 130 bool GrowBlockFile(MappedFile* file, BlockFileHeader* header); 131 132 // Returns the appropriate file to use for a new block. 133 MappedFile* FileForNewBlock(FileType block_type, int block_count); 134 135 // Returns the next block file on this chain, creating new files if needed. 136 MappedFile* NextFile(MappedFile* file); 137 138 // Creates an empty block file and returns its index. 139 int CreateNextBlockFile(FileType block_type); 140 141 // Removes a chained block file that is now empty. 142 bool RemoveEmptyFile(FileType block_type); 143 144 // Restores the header of a potentially inconsistent file. 145 bool FixBlockFileHeader(MappedFile* file); 146 147 // Retrieves stats for the given file index. 148 void GetFileStats(int index, int* used_count, int* load); 149 150 // Returns the filename for a given file index. 151 base::FilePath Name(int index); 152 153 bool init_; 154 char* zero_buffer_; // Buffer to speed-up cleaning deleted entries. 155 base::FilePath path_; // Path to the backing folder. 156 std::vector<MappedFile*> block_files_; // The actual files. 157 scoped_ptr<base::ThreadChecker> thread_checker_; 158 159 FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_ZeroSizeFile); 160 FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_TruncatedFile); 161 FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_InvalidFile); 162 FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_Stats); 163 164 DISALLOW_COPY_AND_ASSIGN(BlockFiles); 165 }; 166 167 } // namespace disk_cache 168 169 #endif // NET_DISK_CACHE_BLOCKFILE_BLOCK_FILES_H_ 170