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
19namespace metrics {
20
21namespace {
22
23uint32 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
32enum 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.
41void LogMachineIdState(MachineIdState state) {
42  UMA_HISTOGRAM_ENUMERATION("UMA.MachineIdState", state, ID_ENUM_SIZE);
43}
44
45}  // namespace
46
47ClonedInstallDetector::ClonedInstallDetector(MachineIdProvider* raw_id_provider)
48    : raw_id_provider_(raw_id_provider), weak_ptr_factory_(this) {
49}
50
51ClonedInstallDetector::~ClonedInstallDetector() {
52}
53
54void 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
66void 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
94void ClonedInstallDetector::RegisterPrefs(PrefRegistrySimple* registry) {
95  registry->RegisterIntegerPref(prefs::kMetricsMachineId, 0);
96}
97
98}  // namespace metrics
99