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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_BLOCKFILE_ADDR_H_ | |
9 #define NET_DISK_CACHE_BLOCKFILE_ADDR_H_ | |
10 | |
11 #include "net/base/net_export.h" | |
12 #include "net/disk_cache/blockfile/disk_format_base.h" | |
13 | |
14 namespace disk_cache { | |
15 | |
16 enum 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 | |
27 const int kMaxBlockSize = 4096 * 4; | |
28 const int16 kMaxBlockFile = 255; | |
29 const int kMaxNumBlocks = 4; | |
30 const int16 kFirstAdditionalBlockFile = 4; | |
31 const size_t 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) | |
57 // | |
58 // Note that an Addr can be used to "point" to a variety of different objects, | |
59 // from a given type of entry to random blobs of data. Conceptually, an Addr is | |
60 // just a number that someone can inspect to find out how to locate the desired | |
61 // record. Most users will not care about the specific bits inside Addr, for | |
62 // example, what parts of it point to a file number; only the code that has to | |
63 // select a specific file would care about those specific bits. | |
64 // | |
65 // From a general point of view, an Addr has a total capacity of 2^24 entities, | |
66 // in that it has 24 bits that can identify individual records. Note that the | |
67 // address space is bigger for independent files (2^28), but that would not be | |
68 // the general case. | |
69 class NET_EXPORT_PRIVATE Addr { | |
70 public: | |
71 Addr() : value_(0) {} | |
72 explicit Addr(CacheAddr address) : value_(address) {} | |
73 Addr(FileType file_type, int max_blocks, int block_file, int index) { | |
74 value_ = ((file_type << kFileTypeOffset) & kFileTypeMask) | | |
75 (((max_blocks - 1) << kNumBlocksOffset) & kNumBlocksMask) | | |
76 ((block_file << kFileSelectorOffset) & kFileSelectorMask) | | |
77 (index & kStartBlockMask) | kInitializedMask; | |
78 } | |
79 | |
80 CacheAddr value() const { return value_; } | |
81 void set_value(CacheAddr address) { | |
82 value_ = address; | |
83 } | |
84 | |
85 bool is_initialized() const { | |
86 return (value_ & kInitializedMask) != 0; | |
87 } | |
88 | |
89 bool is_separate_file() const { | |
90 return (value_ & kFileTypeMask) == 0; | |
91 } | |
92 | |
93 bool is_block_file() const { | |
94 return !is_separate_file(); | |
95 } | |
96 | |
97 FileType file_type() const { | |
98 return static_cast<FileType>((value_ & kFileTypeMask) >> kFileTypeOffset); | |
99 } | |
100 | |
101 int FileNumber() const { | |
102 if (is_separate_file()) | |
103 return value_ & kFileNameMask; | |
104 else | |
105 return ((value_ & kFileSelectorMask) >> kFileSelectorOffset); | |
106 } | |
107 | |
108 int start_block() const; | |
109 int num_blocks() const; | |
110 bool SetFileNumber(int file_number); | |
111 int BlockSize() const { | |
112 return BlockSizeForFileType(file_type()); | |
113 } | |
114 | |
115 bool operator==(Addr other) const { | |
116 return value_ == other.value_; | |
117 } | |
118 | |
119 bool operator!=(Addr other) const { | |
120 return value_ != other.value_; | |
121 } | |
122 | |
123 static int BlockSizeForFileType(FileType file_type) { | |
124 switch (file_type) { | |
125 case RANKINGS: | |
126 return 36; | |
127 case BLOCK_256: | |
128 return 256; | |
129 case BLOCK_1K: | |
130 return 1024; | |
131 case BLOCK_4K: | |
132 return 4096; | |
133 case BLOCK_FILES: | |
134 return 8; | |
135 case BLOCK_ENTRIES: | |
136 return 104; | |
137 case BLOCK_EVICTED: | |
138 return 48; | |
139 default: | |
140 return 0; | |
141 } | |
142 } | |
143 | |
144 static FileType RequiredFileType(int size) { | |
145 if (size < 1024) | |
146 return BLOCK_256; | |
147 else if (size < 4096) | |
148 return BLOCK_1K; | |
149 else if (size <= 4096 * 4) | |
150 return BLOCK_4K; | |
151 else | |
152 return EXTERNAL; | |
153 } | |
154 | |
155 static int RequiredBlocks(int size, FileType file_type) { | |
156 int block_size = BlockSizeForFileType(file_type); | |
157 return (size + block_size - 1) / block_size; | |
158 } | |
159 | |
160 // Returns true if this address looks like a valid one. | |
161 bool SanityCheckV2() const; | |
162 bool SanityCheckV3() const; | |
163 bool SanityCheckForEntryV2() const; | |
164 bool SanityCheckForEntryV3() const; | |
165 bool SanityCheckForRankings() const; | |
166 | |
167 private: | |
168 uint32 reserved_bits() const { | |
169 return value_ & kReservedBitsMask; | |
170 } | |
171 | |
172 static const uint32 kInitializedMask = 0x80000000; | |
173 static const uint32 kFileTypeMask = 0x70000000; | |
174 static const uint32 kFileTypeOffset = 28; | |
175 static const uint32 kReservedBitsMask = 0x0c000000; | |
176 static const uint32 kNumBlocksMask = 0x03000000; | |
177 static const uint32 kNumBlocksOffset = 24; | |
178 static const uint32 kFileSelectorMask = 0x00ff0000; | |
179 static const uint32 kFileSelectorOffset = 16; | |
180 static const uint32 kStartBlockMask = 0x0000FFFF; | |
181 static const uint32 kFileNameMask = 0x0FFFFFFF; | |
182 | |
183 CacheAddr value_; | |
184 }; | |
185 | |
186 } // namespace disk_cache | |
187 | |
188 #endif // NET_DISK_CACHE_BLOCKFILE_ADDR_H_ | |
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