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// This is an internal class that handles the address of a cache record.
6// See net/disk_cache/disk_cache.h for the public interface of the cache.
7
8#ifndef NET_DISK_CACHE_ADDR_H_
9#define NET_DISK_CACHE_ADDR_H_
10
11#include "net/base/net_export.h"
12#include "net/disk_cache/disk_format_base.h"
13
14namespace disk_cache {
15
16enum FileType {
17  EXTERNAL = 0,
18  RANKINGS = 1,
19  BLOCK_256 = 2,
20  BLOCK_1K = 3,
21  BLOCK_4K = 4,
22  BLOCK_FILES = 5,
23  BLOCK_ENTRIES = 6,
24  BLOCK_EVICTED = 7
25};
26
27const int kMaxBlockSize = 4096 * 4;
28const int kMaxBlockFile = 255;
29const int kMaxNumBlocks = 4;
30const int kFirstAdditionalBlockFile = 4;
31const int kFirstAdditionalBlockFileV3 = 7;
32
33// Defines a storage address for a cache record
34//
35// Header:
36//   1000 0000 0000 0000 0000 0000 0000 0000 : initialized bit
37//   0111 0000 0000 0000 0000 0000 0000 0000 : file type
38//
39// File type values:
40//   0 = separate file on disk
41//   1 = rankings block file
42//   2 = 256 byte block file
43//   3 = 1k byte block file
44//   4 = 4k byte block file
45//   5 = external files block file
46//   6 = active entries block file
47//   7 = evicted entries block file
48//
49// If separate file:
50//   0000 1111 1111 1111 1111 1111 1111 1111 : file#  0 - 268,435,456 (2^28)
51//
52// If block file:
53//   0000 1100 0000 0000 0000 0000 0000 0000 : reserved bits
54//   0000 0011 0000 0000 0000 0000 0000 0000 : number of contiguous blocks 1-4
55//   0000 0000 1111 1111 0000 0000 0000 0000 : file selector 0 - 255
56//   0000 0000 0000 0000 1111 1111 1111 1111 : block#  0 - 65,535 (2^16)
57class NET_EXPORT_PRIVATE Addr {
58 public:
59  Addr() : value_(0) {}
60  explicit Addr(CacheAddr address) : value_(address) {}
61  Addr(FileType file_type, int max_blocks, int block_file, int index) {
62    value_ = ((file_type << kFileTypeOffset) & kFileTypeMask) |
63             (((max_blocks - 1) << kNumBlocksOffset) & kNumBlocksMask) |
64             ((block_file << kFileSelectorOffset) & kFileSelectorMask) |
65             (index  & kStartBlockMask) | kInitializedMask;
66  }
67
68  CacheAddr value() const { return value_; }
69  void set_value(CacheAddr address) {
70    value_ = address;
71  }
72
73  bool is_initialized() const {
74    return (value_ & kInitializedMask) != 0;
75  }
76
77  bool is_separate_file() const {
78    return (value_ & kFileTypeMask) == 0;
79  }
80
81  bool is_block_file() const {
82    return !is_separate_file();
83  }
84
85  FileType file_type() const {
86    return static_cast<FileType>((value_ & kFileTypeMask) >> kFileTypeOffset);
87  }
88
89  int FileNumber() const {
90    if (is_separate_file())
91      return value_ & kFileNameMask;
92    else
93      return ((value_ & kFileSelectorMask) >> kFileSelectorOffset);
94  }
95
96  int start_block() const;
97  int num_blocks() const;
98  bool SetFileNumber(int file_number);
99  int BlockSize() const {
100    return BlockSizeForFileType(file_type());
101  }
102
103  bool operator==(Addr other) const {
104    return value_ == other.value_;
105  }
106
107  bool operator!=(Addr other) const {
108    return value_ != other.value_;
109  }
110
111  static Addr FromEntryAddress(uint32 value) {
112    return Addr(kInitializedMask + (BLOCK_ENTRIES << kFileTypeOffset) + value);
113  }
114
115  static Addr FromEvictedAddress(uint32 value) {
116    return Addr(kInitializedMask + (BLOCK_EVICTED << kFileTypeOffset) + value);
117  }
118
119  static int BlockSizeForFileType(FileType file_type) {
120    switch (file_type) {
121      case RANKINGS:
122        return 36;
123      case BLOCK_256:
124        return 256;
125      case BLOCK_1K:
126        return 1024;
127      case BLOCK_4K:
128        return 4096;
129      case BLOCK_FILES:
130        return 8;
131      case BLOCK_ENTRIES:
132        return 104;
133      case BLOCK_EVICTED:
134        return 48;
135      default:
136        return 0;
137    }
138  }
139
140  static FileType RequiredFileType(int size) {
141    if (size < 1024)
142      return BLOCK_256;
143    else if (size < 4096)
144      return BLOCK_1K;
145    else if (size <= 4096 * 4)
146      return BLOCK_4K;
147    else
148      return EXTERNAL;
149  }
150
151  static int RequiredBlocks(int size, FileType file_type) {
152    int block_size = BlockSizeForFileType(file_type);
153    return (size + block_size - 1) / block_size;
154  }
155
156  // Returns true if this address looks like a valid one.
157  bool SanityCheckV2() const;
158  bool SanityCheckV3() const;
159  bool SanityCheckForEntryV2() const;
160  bool SanityCheckForEntryV3() const;
161  bool SanityCheckForRankings() const;
162
163 private:
164  uint32 reserved_bits() const {
165    return value_ & kReservedBitsMask;
166  }
167
168  static const uint32 kInitializedMask    = 0x80000000;
169  static const uint32 kFileTypeMask       = 0x70000000;
170  static const uint32 kFileTypeOffset     = 28;
171  static const uint32 kReservedBitsMask   = 0x0c000000;
172  static const uint32 kNumBlocksMask      = 0x03000000;
173  static const uint32 kNumBlocksOffset    = 24;
174  static const uint32 kFileSelectorMask   = 0x00ff0000;
175  static const uint32 kFileSelectorOffset = 16;
176  static const uint32 kStartBlockMask     = 0x0000FFFF;
177  static const uint32 kFileNameMask       = 0x0FFFFFFF;
178
179  CacheAddr value_;
180};
181
182}  // namespace disk_cache
183
184#endif  // NET_DISK_CACHE_ADDR_H_
185