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Side by Side Diff: chrome/browser/safe_browsing/prefix_set.h

Issue 10892016: Strip out safe-browsing prefix-set checksumming code. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Oops, remove unit test for deleted code. Created 8 years, 3 months ago
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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 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 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 // 4 //
5 // A read-only set implementation for |SBPrefix| items. Prefixes are 5 // A read-only set implementation for |SBPrefix| items. Prefixes are
6 // sorted and stored as 16-bit deltas from the previous prefix. An 6 // sorted and stored as 16-bit deltas from the previous prefix. An
7 // index structure provides quick random access, and also handles 7 // index structure provides quick random access, and also handles
8 // cases where 16 bits cannot encode a delta. 8 // cases where 16 bits cannot encode a delta.
9 // 9 //
10 // For example, the sequence {20, 25, 41, 65432, 150000, 160000} would 10 // For example, the sequence {20, 25, 41, 65432, 150000, 160000} would
(...skipping 55 matching lines...) Expand 10 before | Expand all | Expand 10 after
66 bool Exists(SBPrefix prefix) const; 66 bool Exists(SBPrefix prefix) const;
67 67
68 // Persist the set on disk. 68 // Persist the set on disk.
69 static PrefixSet* LoadFile(const FilePath& filter_name); 69 static PrefixSet* LoadFile(const FilePath& filter_name);
70 bool WriteFile(const FilePath& filter_name) const; 70 bool WriteFile(const FilePath& filter_name) const;
71 71
72 // Regenerate the vector of prefixes passed to the constructor into 72 // Regenerate the vector of prefixes passed to the constructor into
73 // |prefixes|. Prefixes will be added in sorted order. 73 // |prefixes|. Prefixes will be added in sorted order.
74 void GetPrefixes(std::vector<SBPrefix>* prefixes) const; 74 void GetPrefixes(std::vector<SBPrefix>* prefixes) const;
75 75
76 // TODO(shess): The following are debugging accessors. Delete once
77 // the encoding problem is figured out.
78
79 size_t IndexBinFor(size_t target_index) const;
80
81 // The number of prefixes represented.
82 size_t GetSize() const;
83
84 // Returns |true| if the element at |target_index| is between items in the
85 // |index_| array.
86 bool IsDeltaAt(size_t target_index) const;
87
88 // Returns the delta used to calculate the element at
89 // |target_index|. Only call if |IsDeltaAt()| returned |true|.
90 uint16 DeltaAt(size_t target_index) const;
91
92 // Check whether |index_| and |deltas_| still match the checksum
93 // generated during construction.
94 bool CheckChecksum() const;
95
96 // Accumulates xor checksum over what GetPrefixes() would return,
97 // without requiring a large temporary structure.
98 SBPrefix GetPrefixesChecksum() const;
99
100 private: 76 private:
101 // Maximum number of consecutive deltas to encode before generating 77 // Maximum number of consecutive deltas to encode before generating
102 // a new index entry. This helps keep the worst-case performance 78 // a new index entry. This helps keep the worst-case performance
103 // for |Exists()| under control. 79 // for |Exists()| under control.
104 static const size_t kMaxRun = 100; 80 static const size_t kMaxRun = 100;
105 81
106 // Helper for |LoadFile()|. Steals the contents of |index| and 82 // Helper for |LoadFile()|. Steals the contents of |index| and
107 // |deltas| using |swap()|. 83 // |deltas| using |swap()|.
108 PrefixSet(std::vector<std::pair<SBPrefix,size_t> > *index, 84 PrefixSet(std::vector<std::pair<SBPrefix,size_t> > *index,
109 std::vector<uint16> *deltas); 85 std::vector<uint16> *deltas);
110 86
111 // Top-level index of prefix to offset in |deltas_|. Each pair 87 // Top-level index of prefix to offset in |deltas_|. Each pair
112 // indicates a base prefix and where the deltas from that prefix 88 // indicates a base prefix and where the deltas from that prefix
113 // begin in |deltas_|. The deltas for a pair end at the next pair's 89 // begin in |deltas_|. The deltas for a pair end at the next pair's
114 // index into |deltas_|. 90 // index into |deltas_|.
115 std::vector<std::pair<SBPrefix,size_t> > index_; 91 std::vector<std::pair<SBPrefix,size_t> > index_;
116 92
117 // Deltas which are added to the prefix in |index_| to generate 93 // Deltas which are added to the prefix in |index_| to generate
118 // prefixes. Deltas are only valid between consecutive items from 94 // prefixes. Deltas are only valid between consecutive items from
119 // |index_|, or the end of |deltas_| for the last |index_| pair. 95 // |index_|, or the end of |deltas_| for the last |index_| pair.
120 std::vector<uint16> deltas_; 96 std::vector<uint16> deltas_;
121 97
122 // For debugging, used to verify that |index_| and |deltas| were not
123 // changed after generation during construction. |checksum_| is
124 // calculated from the data used to construct those vectors.
125 uint32 checksum_;
126
127 DISALLOW_COPY_AND_ASSIGN(PrefixSet); 98 DISALLOW_COPY_AND_ASSIGN(PrefixSet);
128 }; 99 };
129 100
130 } // namespace safe_browsing 101 } // namespace safe_browsing
131 102
132 #endif // CHROME_BROWSER_SAFE_BROWSING_PREFIX_SET_H_ 103 #endif // CHROME_BROWSER_SAFE_BROWSING_PREFIX_SET_H_
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