blob: c7099994d8dfe6ee8f715934399d8461a3535483 (
plain)
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
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/autocomplete/network_action_predictor.h"
#include <math.h>
#include "base/i18n/case_conversion.h"
#include "base/metrics/histogram.h"
#include "base/string_util.h"
#include "base/utf_string_conversions.h"
#include "chrome/browser/autocomplete/autocomplete_match.h"
#include "chrome/browser/history/history.h"
#include "chrome/browser/history/in_memory_database.h"
#include "chrome/browser/prerender/prerender_field_trial.h"
#include "chrome/browser/profiles/profile.h"
namespace {
const float kConfidenceCutoff[] = {
0.8f,
0.5f
};
COMPILE_ASSERT(arraysize(kConfidenceCutoff) ==
NetworkActionPredictor::LAST_PREDICT_ACTION,
ConfidenceCutoff_count_mismatch);
double OriginalAlgorithm(const history::URLRow& url_row) {
const double base_score = 1.0;
// This constant is ln(1/0.65) so we end up decaying to 65% of the base score
// for each week that passes.
const double kLnDecayPercent = 0.43078291609245;
base::TimeDelta time_passed = base::Time::Now() - url_row.last_visit();
// Clamp to 0.
const double decay_exponent = std::max(0.0,
kLnDecayPercent * static_cast<double>(time_passed.InMicroseconds()) /
base::Time::kMicrosecondsPerWeek);
const double kMaxDecaySpeedDivisor = 5.0;
const double kNumUsesPerDecaySpeedDivisorIncrement = 2.0;
const double decay_divisor = std::min(kMaxDecaySpeedDivisor,
(url_row.typed_count() + kNumUsesPerDecaySpeedDivisorIncrement - 1) /
kNumUsesPerDecaySpeedDivisorIncrement);
return base_score / exp(decay_exponent / decay_divisor);
}
double ConservativeAlgorithm(const history::URLRow& url_row) {
const double normalized_typed_count =
std::min(url_row.typed_count() / 5.0, 1.0);
const double base_score = atan(10 * normalized_typed_count) / atan(10.0);
// This constant is ln(1/0.65) so we end up decaying to 65% of the base score
// for each week that passes.
const double kLnDecayPercent = 0.43078291609245;
base::TimeDelta time_passed = base::Time::Now() - url_row.last_visit();
const double decay_exponent = std::max(0.0,
kLnDecayPercent * static_cast<double>(time_passed.InMicroseconds()) /
base::Time::kMicrosecondsPerWeek);
return base_score / exp(decay_exponent);
}
}
NetworkActionPredictor::NetworkActionPredictor(Profile* profile)
: profile_(profile) {
}
NetworkActionPredictor::~NetworkActionPredictor() {
}
// Given a match, return a recommended action.
NetworkActionPredictor::Action
NetworkActionPredictor::RecommendAction(
const string16& user_text, const AutocompleteMatch& match) const {
HistoryService* history_service =
profile_->GetHistoryService(Profile::EXPLICIT_ACCESS);
if (!history_service)
return ACTION_NONE;
history::URLDatabase* url_db = history_service->InMemoryDatabase();
if (!url_db)
return ACTION_NONE;
history::URLRow url_row;
history::URLID url_id = url_db->GetRowForURL(match.destination_url, &url_row);
if (url_id == 0)
return ACTION_NONE;
double confidence = 0.0;
std::string histogram("NetworkActionPredictor.Confidence_");
switch (prerender::GetOmniboxHeuristicToUse()) {
case prerender::OMNIBOX_HEURISTIC_ORIGINAL:
confidence = OriginalAlgorithm(url_row);
histogram += "Original";
break;
case prerender::OMNIBOX_HEURISTIC_CONSERVATIVE:
confidence = ConservativeAlgorithm(url_row);
histogram += "Conservative";
break;
default:
NOTREACHED();
break;
};
CHECK(confidence >= 0.0 && confidence <= 1.0);
UMA_HISTOGRAM_COUNTS_100(histogram.c_str(), confidence * 100);
for (int i = 0; i < LAST_PREDICT_ACTION; ++i)
if (confidence >= kConfidenceCutoff[i])
return static_cast<Action>(i);
return ACTION_NONE;
}
// Return true if the suggestion type warrants a TCP/IP preconnection.
// i.e., it is now quite likely that the user will select the related domain.
// static
bool NetworkActionPredictor::IsPreconnectable(const AutocompleteMatch& match) {
switch (match.type) {
// Matches using the user's default search engine.
case AutocompleteMatch::SEARCH_WHAT_YOU_TYPED:
case AutocompleteMatch::SEARCH_HISTORY:
case AutocompleteMatch::SEARCH_SUGGEST:
// A match that uses a non-default search engine (e.g. for tab-to-search).
case AutocompleteMatch::SEARCH_OTHER_ENGINE:
return true;
default:
return false;
}
}
|
