1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_VARIATIONS_VARIATIONS_LAYERS_H_
#define COMPONENTS_VARIATIONS_VARIATIONS_LAYERS_H_
#include <map>
#include "base/component_export.h"
#include "base/metrics/field_trial.h"
#include "components/variations/entropy_provider.h"
#include "components/variations/proto/variations_seed.pb.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
namespace variations {
enum class InvalidLayerReason {
kInvalidId = 0,
kNoSlots = 1,
kNoMembers = 2,
kInvalidEntropyMode = 3,
kSlotsDoNotDivideLowEntropyDomain = 4,
kInvalidSlotBounds = 5,
kUnknownFields = 6,
kMaxValue = kUnknownFields,
};
// A view over the layers defined within a variations seed.
//
// A layer defines a collection of mutually exclusive members. For each client,
// at most one member will be assigned as its active member. Studies may be
// conditioned on a particular member being active, in order to avoid overlap
// with studies that require a different member to be active.
class COMPONENT_EXPORT(VARIATIONS) VariationsLayers {
public:
VariationsLayers(const VariationsSeed& seed,
const EntropyProviders& entropy_providers);
VariationsLayers();
~VariationsLayers();
VariationsLayers(const VariationsLayers&) = delete;
VariationsLayers& operator=(const VariationsLayers&) = delete;
// Returns whether the given layer has the given member active.
bool IsLayerMemberActive(uint32_t layer_id, uint32_t member_id) const;
// Returns true if the layer has an active member and is configured to use
// DEFAULT entropy, which means that any study conditioned on it would leak
// information about the client's high entropy source (including whether or
// not the client _has_ a high entropy source).
bool ActiveLayerMemberDependsOnHighEntropy(uint32_t layer_id) const;
// Gets an EntropyProvider for low entropy randomization of studies
// conditioned on the layer's active member.
const base::FieldTrial::EntropyProvider& GetRemainderEntropy(
uint32_t layer_id) const;
private:
struct LayerInfo {
// Which layer member is active in the layer.
uint32_t active_member_id;
// The type of entropy the layer was configured to use.
Layer::EntropyMode entropy_mode;
// If this layer has an active member, this is the remaining entropy from
// that selection, which can be used for uniform randomization of studies
// conditioned on that layer member.
// See ComputeRemainderEntropy() for details.
NormalizedMurmurHashEntropyProvider remainder_entropy;
};
void ConstructLayer(const EntropyProviders& entropy_providers,
const Layer& layer_proto);
NormalizedMurmurHashEntropyProvider nil_entropy;
std::map<uint32_t, LayerInfo> active_member_for_layer_;
};
} // namespace variations
#endif // COMPONENTS_VARIATIONS_VARIATIONS_LAYERS_H_
|
