chromeos/dbus/metronome_client.cc

   1 // Copyright 2015 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 "chromeos/dbus/metronome_client.h"
   6
   7 #include "base/bind.h"
   8 #include "base/rand_util.h"
   9 #include "base/command_line.h"
  10 #include "base/logging.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "base/observer_list.h"
  13 #include "base/time/time.h"
  14 #include "base/timer/timer.h"
  15 #include "chromeos/chromeos_switches.h"
  16 #include "dbus/bus.h"
  17 #include "dbus/message.h"
  18 #include "dbus/object_path.h"
  19 #include "dbus/object_proxy.h"
  20
  21 // TODO(benchan): Move these DBus constants to system_api.
  22 namespace metronome {
  23
  24 const char kMetronomeInterface[] = "org.chromium.Metronome";
  25 const char kMetronomeServiceName[] = "org.chromium.Metronome";
  26 const char kMetronomeServicePath[] = "/org/chromium/Metronome";
  27 const char kTimestampUpdatedSignal[] = "TimestampUpdated";
  28
  29 }  // namespace metronome
  30
  31 namespace chromeos {
  32
  33 namespace {
  34
  35 ////////////////////////////////////////////////////////////////////////////////
  36
  37 // The MetronomeClient implementation.
  38 class MetronomeClientImpl : public MetronomeClient {
  39  public:
  40   MetronomeClientImpl()
  41       : proxy_(nullptr), signal_connected_(false), weak_ptr_factory_(this) {}
  42
  43   ~MetronomeClientImpl() override {}
  44
  45   // MetronomeClient:
  46   void AddObserver(Observer* observer) override;
  47   void RemoveObserver(Observer* observer) override;
  48
  49  protected:
  50   // DBusClient:
  51   void Init(dbus::Bus* bus) override;
  52
  53  private:
  54   // Handles TimestampUpdated signal and notifies |observers_|.
  55   void OnTimestampUpdated(dbus::Signal* signal);
  56
  57   // Handles the result of signal connection setup.
  58   void OnSignalConnected(const std::string& interface,
  59                          const std::string& signal,
  60                          bool succeeded);
  61
  62   dbus::ObjectProxy* proxy_;
  63
  64   // True when |proxy_| has been connected.
  65   bool signal_connected_;
  66
  67   // List of observers interested in event notifications from us.
  68   base::ObserverList<Observer> observers_;
  69
  70   // Note: This should remain the last member so it'll be destroyed and
  71   // invalidate its weak pointers before any other members are destroyed.
  72   base::WeakPtrFactory<MetronomeClientImpl> weak_ptr_factory_;
  73
  74   DISALLOW_COPY_AND_ASSIGN(MetronomeClientImpl);
  75 };
  76
  77 void MetronomeClientImpl::AddObserver(Observer* observer) {
  78   DCHECK(observer);
  79   if (!signal_connected_) {
  80     signal_connected_ = true;
  81     proxy_->ConnectToSignal(metronome::kMetronomeInterface,
  82                             metronome::kTimestampUpdatedSignal,
  83                             base::Bind(&MetronomeClientImpl::OnTimestampUpdated,
  84                                        weak_ptr_factory_.GetWeakPtr()),
  85                             base::Bind(&MetronomeClientImpl::OnSignalConnected,
  86                                        weak_ptr_factory_.GetWeakPtr()));
  87   }
  88   observers_.AddObserver(observer);
  89 }
  90
  91 void MetronomeClientImpl::RemoveObserver(Observer* observer) {
  92   DCHECK(observer);
  93   observers_.RemoveObserver(observer);
  94 }
  95
  96 void MetronomeClientImpl::Init(dbus::Bus* bus) {
  97   proxy_ =
  98       bus->GetObjectProxy(metronome::kMetronomeServiceName,
  99                           dbus::ObjectPath(metronome::kMetronomeServicePath));
 100 }
 101
 102 void MetronomeClientImpl::OnTimestampUpdated(dbus::Signal* signal) {
 103   dbus::MessageReader reader(signal);
 104   uint64 beacon_timestamp = 0;
 105   uint64 local_timestamp = 0;
 106   if (!reader.PopUint64(&beacon_timestamp) ||
 107       !reader.PopUint64(&local_timestamp)) {
 108     LOG(ERROR) << "Invalid signal: " << signal->ToString();
 109     return;
 110   }
 111   FOR_EACH_OBSERVER(Observer, observers_,
 112                     OnTimestampUpdated(beacon_timestamp, local_timestamp));
 113 }
 114
 115 void MetronomeClientImpl::OnSignalConnected(const std::string& interface,
 116                                             const std::string& signal,
 117                                             bool succeeded) {
 118   LOG_IF(ERROR, !succeeded) << "Connect to " << interface << " " << signal
 119                             << " failed.";
 120 }
 121
 122 ////////////////////////////////////////////////////////////////////////////////
 123
 124 // A fake implementation of MetronomeClient. It does not provide true
 125 // synchronization and only exists to exercise the interfaces.
 126 class MetronomeClientFakeImpl : public MetronomeClient {
 127  public:
 128   MetronomeClientFakeImpl()
 129       : random_offset_(base::RandInt(-1000000, 1000000)) {}
 130
 131   ~MetronomeClientFakeImpl() override { beacon_timer_.Stop(); }
 132
 133   // MetronomeClient:
 134   void AddObserver(Observer* observer) override {
 135     DCHECK(observer);
 136     observers_.AddObserver(observer);
 137   }
 138
 139   void RemoveObserver(Observer* observer) override {
 140     DCHECK(observer);
 141     observers_.RemoveObserver(observer);
 142   }
 143
 144   // DBusClient:
 145   void Init(dbus::Bus* bus) override {
 146     beacon_timer_.Start(FROM_HERE,
 147                         base::TimeDelta::FromMilliseconds(1000),
 148                         this,
 149                         &MetronomeClientFakeImpl::UpdateBeacon);
 150   }
 151
 152  private:
 153   void UpdateBeacon() {
 154     base::Time now_time = base::Time::Now();
 155     base::TimeTicks now_ticks = base::TimeTicks::Now();
 156     uint64 fake_beacon_timestamp = now_time.ToInternalValue() +
 157                                    base::RandInt(-1000, 1000);
 158     uint64 fake_local_timestamp = now_ticks.ToInternalValue() + random_offset_ +
 159                                   base::RandInt(-1000, 1000);
 160     FOR_EACH_OBSERVER(
 161         Observer, observers_,
 162         OnTimestampUpdated(fake_beacon_timestamp, fake_local_timestamp));
 163   }
 164
 165   int64 random_offset_;
 166   base::RepeatingTimer<MetronomeClientFakeImpl> beacon_timer_;
 167
 168   // List of observers interested in event notifications from us.
 169   base::ObserverList<Observer> observers_;
 170
 171   DISALLOW_COPY_AND_ASSIGN(MetronomeClientFakeImpl);
 172 };
 173
 174 ////////////////////////////////////////////////////////////////////////////////
 175
 176 // A stub implementation of MetronomeClient. It allows unit tests to complete.
 177 class MetronomeClientStubImpl : public MetronomeClient {
 178  public:
 179   MetronomeClientStubImpl() {}
 180   ~MetronomeClientStubImpl() override {}
 181
 182   // MetronomeClient:
 183   void AddObserver(Observer* observer) override {}
 184   void RemoveObserver(Observer* observer) override {}
 185
 186   // DBusClient:
 187   void Init(dbus::Bus* bus) override {}
 188
 189  private:
 190   DISALLOW_COPY_AND_ASSIGN(MetronomeClientStubImpl);
 191 };
 192
 193 }  // namespace
 194
 195 ////////////////////////////////////////////////////////////////////////////////
 196
 197 MetronomeClient::MetronomeClient() {
 198 }
 199
 200 MetronomeClient::~MetronomeClient() {
 201 }
 202
 203 // static
 204 MetronomeClient* MetronomeClient::Create(DBusClientImplementationType type) {
 205   if (type == REAL_DBUS_CLIENT_IMPLEMENTATION)
 206     return new MetronomeClientImpl();
 207   DCHECK_EQ(STUB_DBUS_CLIENT_IMPLEMENTATION, type);
 208
 209   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
 210           switches::kTestMetronomeTimer)) {
 211     return new MetronomeClientFakeImpl();
 212   }
 213   return new MetronomeClientStubImpl();
 214 }
 215
 216 }  // namespace chromeos