src/chrome/browser/chromeos/session_length_limiter.cc

   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
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/chromeos/session_length_limiter.h"
   6
   7 #include <algorithm>
   8
   9 #include "ash/shell.h"
  10 #include "ash/wm/user_activity_detector.h"
  11 #include "base/bind.h"
  12 #include "base/bind_helpers.h"
  13 #include "base/location.h"
  14 #include "base/logging.h"
  15 #include "base/prefs/pref_registry_simple.h"
  16 #include "base/prefs/pref_service.h"
  17 #include "chrome/browser/browser_process.h"
  18 #include "chrome/browser/lifetime/application_lifetime.h"
  19 #include "chrome/common/pref_names.h"
  20 #include "ui/events/event.h"
  21
  22 namespace chromeos {
  23
  24 namespace {
  25
  26 // The minimum session time limit that can be set.
  27 const int kSessionLengthLimitMinMs = 30 * 1000; // 30 seconds.
  28
  29 // The maximum session time limit that can be set.
  30 const int kSessionLengthLimitMaxMs = 24 * 60 * 60 * 1000; // 24 hours.
  31
  32 // A default delegate implementation that returns the current time and does end
  33 // the current user's session when requested. This can be replaced with a mock
  34 // in tests.
  35 class SessionLengthLimiterDelegateImpl : public SessionLengthLimiter::Delegate {
  36  public:
  37   SessionLengthLimiterDelegateImpl();
  38   virtual ~SessionLengthLimiterDelegateImpl();
  39
  40   virtual const base::TimeTicks GetCurrentTime() const OVERRIDE;
  41   virtual void StopSession() OVERRIDE;
  42
  43  private:
  44   DISALLOW_COPY_AND_ASSIGN(SessionLengthLimiterDelegateImpl);
  45 };
  46
  47 SessionLengthLimiterDelegateImpl::SessionLengthLimiterDelegateImpl() {
  48 }
  49
  50 SessionLengthLimiterDelegateImpl::~SessionLengthLimiterDelegateImpl() {
  51 }
  52
  53 const base::TimeTicks SessionLengthLimiterDelegateImpl::GetCurrentTime() const {
  54   return base::TimeTicks::Now();
  55 }
  56
  57 void SessionLengthLimiterDelegateImpl::StopSession() {
  58   chrome::AttemptUserExit();
  59 }
  60
  61 }  // namespace
  62
  63 SessionLengthLimiter::Delegate::~Delegate() {
  64 }
  65
  66 // static
  67 void SessionLengthLimiter::RegisterPrefs(PrefRegistrySimple* registry) {
  68   registry->RegisterBooleanPref(prefs::kSessionUserActivitySeen, false);
  69   registry->RegisterInt64Pref(prefs::kSessionStartTime, 0);
  70   registry->RegisterIntegerPref(prefs::kSessionLengthLimit, 0);
  71   registry->RegisterBooleanPref(prefs::kSessionWaitForInitialUserActivity,
  72                                 false);
  73 }
  74
  75 SessionLengthLimiter::SessionLengthLimiter(Delegate* delegate,
  76                                            bool browser_restarted)
  77     : delegate_(delegate ? delegate : new SessionLengthLimiterDelegateImpl),
  78       user_activity_seen_(false) {
  79   DCHECK(thread_checker_.CalledOnValidThread());
  80
  81   PrefService* local_state = g_browser_process->local_state();
  82   pref_change_registrar_.Init(local_state);
  83   pref_change_registrar_.Add(prefs::kSessionLengthLimit,
  84                              base::Bind(&SessionLengthLimiter::UpdateLimit,
  85                                         base::Unretained(this)));
  86   pref_change_registrar_.Add(
  87       prefs::kSessionWaitForInitialUserActivity,
  88       base::Bind(&SessionLengthLimiter::UpdateSessionStartTime,
  89                  base::Unretained(this)));
  90
  91   // If this is a browser restart after a crash, try to restore the session
  92   // start time and the boolean indicating user activity from local state. If
  93   // this is not a browser restart after a crash or the attempt to restore
  94   // fails, set  the session start time to the current time and clear the
  95   // boolean indicating user activity.
  96   if (!browser_restarted || !RestoreStateAfterCrash()) {
  97     local_state->ClearPref(prefs::kSessionUserActivitySeen);
  98     UpdateSessionStartTime();
  99   }
 100
 101   if (!user_activity_seen_ && ash::Shell::HasInstance())
 102     ash::Shell::GetInstance()->user_activity_detector()->AddObserver(this);
 103 }
 104
 105 SessionLengthLimiter::~SessionLengthLimiter() {
 106   if (!user_activity_seen_ && ash::Shell::HasInstance())
 107     ash::Shell::GetInstance()->user_activity_detector()->RemoveObserver(this);
 108 }
 109
 110 void SessionLengthLimiter::OnUserActivity(const ui::Event* event) {
 111   if (user_activity_seen_)
 112     return;
 113   if (ash::Shell::HasInstance())
 114     ash::Shell::GetInstance()->user_activity_detector()->RemoveObserver(this);
 115   user_activity_seen_ = true;
 116
 117   PrefService* local_state = g_browser_process->local_state();
 118   local_state->SetBoolean(prefs::kSessionUserActivitySeen, true);
 119   if (session_start_time_.is_null()) {
 120     // If instructed to wait for initial user activity and this is the first
 121     // activity in the session, set the session start time to the current time
 122     // and persist it in local state.
 123     session_start_time_ = delegate_->GetCurrentTime();
 124     local_state->SetInt64(prefs::kSessionStartTime,
 125                           session_start_time_.ToInternalValue());
 126   }
 127   local_state->CommitPendingWrite();
 128
 129   UpdateLimit();
 130 }
 131
 132 bool SessionLengthLimiter::RestoreStateAfterCrash() {
 133   PrefService* local_state = g_browser_process->local_state();
 134   const base::TimeTicks session_start_time =
 135       base::TimeTicks::FromInternalValue(
 136           local_state->GetInt64(prefs::kSessionStartTime));
 137   if (session_start_time.is_null() ||
 138       session_start_time >= delegate_->GetCurrentTime()) {
 139     return false;
 140   }
 141
 142   session_start_time_ = session_start_time;
 143   user_activity_seen_ =
 144       local_state->GetBoolean(prefs::kSessionUserActivitySeen);
 145
 146   UpdateLimit();
 147   return true;
 148 }
 149
 150 void SessionLengthLimiter::UpdateSessionStartTime() {
 151   DCHECK(thread_checker_.CalledOnValidThread());
 152
 153   if (user_activity_seen_)
 154     return;
 155
 156   PrefService* local_state = g_browser_process->local_state();
 157   if (local_state->GetBoolean(prefs::kSessionWaitForInitialUserActivity)) {
 158     session_start_time_ = base::TimeTicks();
 159     local_state->ClearPref(prefs::kSessionStartTime);
 160   } else {
 161     session_start_time_ = delegate_->GetCurrentTime();
 162     local_state->SetInt64(prefs::kSessionStartTime,
 163                           session_start_time_.ToInternalValue());
 164   }
 165   local_state->CommitPendingWrite();
 166
 167   UpdateLimit();
 168 }
 169
 170 void SessionLengthLimiter::UpdateLimit() {
 171   DCHECK(thread_checker_.CalledOnValidThread());
 172
 173   // Stop any currently running timer.
 174   timer_.reset();
 175
 176   // If instructed to wait for initial user activity and no user activity has
 177   // occurred yet, do not start a timer.
 178   if (session_start_time_.is_null())
 179     return;
 180
 181   // If no session length limit is set, do not start a timer.
 182   int limit;
 183   const PrefService::Preference* session_length_limit_pref =
 184       pref_change_registrar_.prefs()->
 185           FindPreference(prefs::kSessionLengthLimit);
 186   if (session_length_limit_pref->IsDefaultValue() ||
 187       !session_length_limit_pref->GetValue()->GetAsInteger(&limit)) {
 188     return;
 189   }
 190
 191   // Clamp the session length limit to the valid range.
 192   const base::TimeDelta session_length_limit =
 193       base::TimeDelta::FromMilliseconds(std::min(std::max(
 194           limit, kSessionLengthLimitMinMs), kSessionLengthLimitMaxMs));
 195
 196   // Calculate the remaining session time.
 197   const base::TimeDelta remaining = session_length_limit -
 198       (delegate_->GetCurrentTime() - session_start_time_);
 199
 200   // Log out the user immediately if the session length limit has been reached
 201   // or exceeded.
 202   if (remaining <= base::TimeDelta()) {
 203     delegate_->StopSession();
 204     return;
 205   }
 206
 207   // Set a timer to log out the user when the session length limit is reached.
 208   timer_.reset(new base::OneShotTimer<SessionLengthLimiter::Delegate>);
 209   timer_->Start(FROM_HERE, remaining, delegate_.get(),
 210                 &SessionLengthLimiter::Delegate::StopSession);
 211 }
 212
 213 }  // namespace chromeos