1 // Copyright 2014 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 #include "components/metrics/cloned_install_detector.h"
6
7 #include "base/bind.h"
8 #include "base/location.h"
9 #include "base/metrics/histogram.h"
10 #include "base/prefs/pref_registry_simple.h"
11 #include "base/prefs/pref_service.h"
12 #include "base/single_thread_task_runner.h"
13 #include "base/task_runner_util.h"
14 #include "components/metrics/cloned_install_detector.h"
15 #include "components/metrics/machine_id_provider.h"
16 #include "components/metrics/metrics_hashes.h"
17 #include "components/metrics/metrics_pref_names.h"
18
19 namespace metrics {
20
21 namespace {
22
HashRawId(const std::string & value)23 uint32 HashRawId(const std::string& value) {
24 uint64 hash = metrics::HashMetricName(value);
25
26 // Only use 24 bits from the 64-bit hash.
27 return hash & ((1 << 24) - 1);
28 }
29
30 // State of the generated machine id in relation to the previously stored value.
31 // Note: UMA histogram enum - don't re-order or remove entries
32 enum MachineIdState {
33 ID_GENERATION_FAILED,
34 ID_NO_STORED_VALUE,
35 ID_CHANGED,
36 ID_UNCHANGED,
37 ID_ENUM_SIZE
38 };
39
40 // Logs the state of generating a machine id and comparing it to a stored value.
LogMachineIdState(MachineIdState state)41 void LogMachineIdState(MachineIdState state) {
42 UMA_HISTOGRAM_ENUMERATION("UMA.MachineIdState", state, ID_ENUM_SIZE);
43 }
44
45 } // namespace
46
ClonedInstallDetector(MachineIdProvider * raw_id_provider)47 ClonedInstallDetector::ClonedInstallDetector(MachineIdProvider* raw_id_provider)
48 : raw_id_provider_(raw_id_provider), weak_ptr_factory_(this) {
49 }
50
~ClonedInstallDetector()51 ClonedInstallDetector::~ClonedInstallDetector() {
52 }
53
CheckForClonedInstall(PrefService * local_state,scoped_refptr<base::SingleThreadTaskRunner> task_runner)54 void ClonedInstallDetector::CheckForClonedInstall(
55 PrefService* local_state,
56 scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
57 base::PostTaskAndReplyWithResult(
58 task_runner.get(),
59 FROM_HERE,
60 base::Bind(&metrics::MachineIdProvider::GetMachineId, raw_id_provider_),
61 base::Bind(&metrics::ClonedInstallDetector::SaveMachineId,
62 weak_ptr_factory_.GetWeakPtr(),
63 local_state));
64 }
65
SaveMachineId(PrefService * local_state,std::string raw_id)66 void ClonedInstallDetector::SaveMachineId(PrefService* local_state,
67 std::string raw_id) {
68 if (raw_id.empty()) {
69 LogMachineIdState(ID_GENERATION_FAILED);
70 local_state->ClearPref(prefs::kMetricsMachineId);
71 return;
72 }
73
74 int hashed_id = HashRawId(raw_id);
75
76 MachineIdState id_state = ID_NO_STORED_VALUE;
77 if (local_state->HasPrefPath(prefs::kMetricsMachineId)) {
78 if (local_state->GetInteger(prefs::kMetricsMachineId) != hashed_id) {
79 id_state = ID_CHANGED;
80 // TODO(jwd): Use a callback to set the reset pref. That way
81 // ClonedInstallDetector doesn't need to know about this pref.
82 local_state->SetBoolean(prefs::kMetricsResetIds, true);
83 } else {
84 id_state = ID_UNCHANGED;
85 }
86 }
87
88 LogMachineIdState(id_state);
89
90 local_state->SetInteger(prefs::kMetricsMachineId, hashed_id);
91 }
92
93 // static
RegisterPrefs(PrefRegistrySimple * registry)94 void ClonedInstallDetector::RegisterPrefs(PrefRegistrySimple* registry) {
95 registry->RegisterIntegerPref(prefs::kMetricsMachineId, 0);
96 }
97
98 } // namespace metrics
99