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Side by Side Diff: components/variations/entropy_provider.h

Issue 1549993003: Switch to standard integer types in components/, part 4 of 4. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 4 years, 12 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 #ifndef COMPONENTS_VARIATIONS_ENTROPY_PROVIDER_H_ 5 #ifndef COMPONENTS_VARIATIONS_ENTROPY_PROVIDER_H_
6 #define COMPONENTS_VARIATIONS_ENTROPY_PROVIDER_H_ 6 #define COMPONENTS_VARIATIONS_ENTROPY_PROVIDER_H_
7 7
8 #include <stddef.h>
9 #include <stdint.h>
10
8 #include <functional> 11 #include <functional>
9 #include <string> 12 #include <string>
10 #include <vector> 13 #include <vector>
11 14
12 #include "base/basictypes.h"
13 #include "base/compiler_specific.h" 15 #include "base/compiler_specific.h"
16 #include "base/macros.h"
14 #include "base/metrics/field_trial.h" 17 #include "base/metrics/field_trial.h"
15 #include "third_party/mt19937ar/mt19937ar.h" 18 #include "third_party/mt19937ar/mt19937ar.h"
16 19
17 namespace metrics { 20 namespace metrics {
18 21
19 // Internals of entropy_provider.cc exposed for testing. 22 // Internals of entropy_provider.cc exposed for testing.
20 namespace internal { 23 namespace internal {
21 24
22 // A functor that generates random numbers based on a seed, using the Mersenne 25 // A functor that generates random numbers based on a seed, using the Mersenne
23 // Twister algorithm. Suitable for use with std::random_shuffle(). 26 // Twister algorithm. Suitable for use with std::random_shuffle().
24 struct SeededRandGenerator : std::unary_function<uint32, uint32> { 27 struct SeededRandGenerator : std::unary_function<uint32_t, uint32_t> {
25 explicit SeededRandGenerator(uint32 seed); 28 explicit SeededRandGenerator(uint32_t seed);
26 ~SeededRandGenerator(); 29 ~SeededRandGenerator();
27 30
28 // Returns a random number in range [0, range). 31 // Returns a random number in range [0, range).
29 uint32 operator()(uint32 range); 32 uint32_t operator()(uint32_t range);
30 33
31 MersenneTwister mersenne_twister_; 34 MersenneTwister mersenne_twister_;
32 }; 35 };
33 36
34 // Fills |mapping| to create a bijection of values in the range of 37 // Fills |mapping| to create a bijection of values in the range of
35 // [0, |mapping.size()|), permuted based on |randomization_seed|. 38 // [0, |mapping.size()|), permuted based on |randomization_seed|.
36 void PermuteMappingUsingRandomizationSeed(uint32 randomization_seed, 39 void PermuteMappingUsingRandomizationSeed(uint32_t randomization_seed,
37 std::vector<uint16>* mapping); 40 std::vector<uint16_t>* mapping);
38 41
39 } // namespace internal 42 } // namespace internal
40 43
41 // SHA1EntropyProvider is an entropy provider suitable for high entropy 44 // SHA1EntropyProvider is an entropy provider suitable for high entropy
42 // sources. It works by taking the first 64 bits of the SHA1 hash of the 45 // sources. It works by taking the first 64 bits of the SHA1 hash of the
43 // entropy source concatenated with the trial name and using that for the 46 // entropy source concatenated with the trial name and using that for the
44 // final entropy value. 47 // final entropy value.
45 class SHA1EntropyProvider : public base::FieldTrial::EntropyProvider { 48 class SHA1EntropyProvider : public base::FieldTrial::EntropyProvider {
46 public: 49 public:
47 // Creates a SHA1EntropyProvider with the given |entropy_source|, which 50 // Creates a SHA1EntropyProvider with the given |entropy_source|, which
48 // should contain a large amount of entropy - for example, a textual 51 // should contain a large amount of entropy - for example, a textual
49 // representation of a persistent randomly-generated 128-bit value. 52 // representation of a persistent randomly-generated 128-bit value.
50 explicit SHA1EntropyProvider(const std::string& entropy_source); 53 explicit SHA1EntropyProvider(const std::string& entropy_source);
51 ~SHA1EntropyProvider() override; 54 ~SHA1EntropyProvider() override;
52 55
53 // base::FieldTrial::EntropyProvider implementation: 56 // base::FieldTrial::EntropyProvider implementation:
54 double GetEntropyForTrial(const std::string& trial_name, 57 double GetEntropyForTrial(const std::string& trial_name,
55 uint32 randomization_seed) const override; 58 uint32_t randomization_seed) const override;
56 59
57 private: 60 private:
58 std::string entropy_source_; 61 std::string entropy_source_;
59 62
60 DISALLOW_COPY_AND_ASSIGN(SHA1EntropyProvider); 63 DISALLOW_COPY_AND_ASSIGN(SHA1EntropyProvider);
61 }; 64 };
62 65
63 // PermutedEntropyProvider is an entropy provider suitable for low entropy 66 // PermutedEntropyProvider is an entropy provider suitable for low entropy
64 // sources (below 16 bits). It uses the field trial name to generate a 67 // sources (below 16 bits). It uses the field trial name to generate a
65 // permutation of a mapping array from an initial entropy value to a new value. 68 // permutation of a mapping array from an initial entropy value to a new value.
66 // Note: This provider's performance is O(2^n), where n is the number of bits 69 // Note: This provider's performance is O(2^n), where n is the number of bits
67 // in the entropy source. 70 // in the entropy source.
68 class PermutedEntropyProvider : public base::FieldTrial::EntropyProvider { 71 class PermutedEntropyProvider : public base::FieldTrial::EntropyProvider {
69 public: 72 public:
70 // Creates a PermutedEntropyProvider with the given |low_entropy_source|, 73 // Creates a PermutedEntropyProvider with the given |low_entropy_source|,
71 // which should have a value in the range of [0, low_entropy_source_max). 74 // which should have a value in the range of [0, low_entropy_source_max).
72 PermutedEntropyProvider(uint16 low_entropy_source, 75 PermutedEntropyProvider(uint16_t low_entropy_source,
73 size_t low_entropy_source_max); 76 size_t low_entropy_source_max);
74 ~PermutedEntropyProvider() override; 77 ~PermutedEntropyProvider() override;
75 78
76 // base::FieldTrial::EntropyProvider implementation: 79 // base::FieldTrial::EntropyProvider implementation:
77 double GetEntropyForTrial(const std::string& trial_name, 80 double GetEntropyForTrial(const std::string& trial_name,
78 uint32 randomization_seed) const override; 81 uint32_t randomization_seed) const override;
79 82
80 protected: 83 protected:
81 // Performs the permutation algorithm and returns the permuted value that 84 // Performs the permutation algorithm and returns the permuted value that
82 // corresponds to |low_entropy_source_|. 85 // corresponds to |low_entropy_source_|.
83 virtual uint16 GetPermutedValue(uint32 randomization_seed) const; 86 virtual uint16_t GetPermutedValue(uint32_t randomization_seed) const;
84 87
85 private: 88 private:
86 uint16 low_entropy_source_; 89 uint16_t low_entropy_source_;
87 size_t low_entropy_source_max_; 90 size_t low_entropy_source_max_;
88 91
89 DISALLOW_COPY_AND_ASSIGN(PermutedEntropyProvider); 92 DISALLOW_COPY_AND_ASSIGN(PermutedEntropyProvider);
90 }; 93 };
91 94
92 } // namespace metrics 95 } // namespace metrics
93 96
94 #endif // COMPONENTS_VARIATIONS_ENTROPY_PROVIDER_H_ 97 #endif // COMPONENTS_VARIATIONS_ENTROPY_PROVIDER_H_
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