Adds metronome time sync dbus client

chromeos/dbus/metronome_client.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.

[dtapuska, 2015/02/18 13:59:12]

Copyrights should be 2015.

[varkha, 2015/02/18 18:21:17]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chromeos/dbus/metronome_client.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "dbus/bus.h"
+#include "dbus/message.h"
+#include "dbus/object_path.h"
+#include "dbus/object_proxy.h"
+
+// TODO(benchan): Move these DBus constants to system_api.
+namespace metronome {
+
+const char kMetronomeInterface[] = "org.chromium.Metronome";
+const char kMetronomeServiceName[] = "org.chromium.Metronome";
+const char kMetronomeServicePath[] = "/org/chromium/Metronome";
+const char kTimestampUpdatedSignal[] = "TimestampUpdated";
+
+}  // namespace metronome
+
+namespace chromeos {
+
+namespace {
+
+////////////////////////////////////////////////////////////////////////////////
+
+// The MetronomeClient implementation.
+class MetronomeClientImpl : public MetronomeClient {
+ public:
+  MetronomeClientImpl() : proxy_(NULL), weak_ptr_factory_(this) {}
+
+  virtual ~MetronomeClientImpl() {}
+
+  // MetronomeClient override.
+  virtual void SetTimestampUpdatedHandler(

[dtapuska, 2015/02/18 13:59:12]

Remove the virtual

[varkha, 2015/02/18 18:21:17]

Done.

+      const TimestampUpdatedHandler& timestamp_updated_handler) override {
+    proxy_->ConnectToSignal(
+        metronome::kMetronomeInterface, metronome::kTimestampUpdatedSignal,
+        base::Bind(&MetronomeClientImpl::OnTimestampUpdated,
+                   weak_ptr_factory_.GetWeakPtr(), timestamp_updated_handler),
+        base::Bind(&MetronomeClientImpl::OnSignalConnected,
+                   weak_ptr_factory_.GetWeakPtr()));
+  }
+
+ protected:
+  virtual void Init(dbus::Bus* bus) override {

[dtapuska, 2015/02/18 13:59:12]

Remove the virtual

[varkha, 2015/02/18 18:21:17]

Done.

+    proxy_ =
+        bus->GetObjectProxy(metronome::kMetronomeServiceName,
+                            dbus::ObjectPath(metronome::kMetronomeServicePath));
+  }
+
+ private:
+  // Handles TimestampUpdated signal and calls |handler|.
+  void OnTimestampUpdated(TimestampUpdatedHandler handler,
+                          dbus::Signal* signal) {
+    dbus::MessageReader reader(signal);
+    uint64 beacon_timestamp = 0;
+    uint64 mac_timestamp = 0;
+    if (!reader.PopUint64(&beacon_timestamp) ||
+        !reader.PopUint64(&mac_timestamp)) {
+      LOG(ERROR) << "Invalid signal: " << signal->ToString();
+      return;
+    }
+    handler.Run(beacon_timestamp, mac_timestamp);
+  }
+
+  // Handles the result of signal connection setup.
+  void OnSignalConnected(const std::string& interface,
+                         const std::string& signal,
+                         bool succeeded) {
+    LOG_IF(ERROR, !succeeded) << "Connect to " << interface << " " << signal
+                              << " failed.";
+  }
+
+  dbus::ObjectProxy* proxy_;
+
+  // Note: This should remain the last member so it'll be destroyed and
+  // invalidate its weak pointers before any other members are destroyed.
+  base::WeakPtrFactory<MetronomeClientImpl> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(MetronomeClientImpl);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+// A stub implementation of MetronomeClient.
+class MetronomeClientStubImpl : public MetronomeClient {
+ public:
+  MetronomeClientStubImpl() : weak_ptr_factory_(this), timer_(true, true) {}
+
+  virtual ~MetronomeClientStubImpl() { timer_.Stop(); }
+
+  // MetronomeClient overrides:
+  virtual void Init(dbus::Bus* bus) override {
+    timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(1000),
+                 base::Bind(&MetronomeClientStubImpl::OnTimer,
+                            weak_ptr_factory_.GetWeakPtr()));
+  }
+
+  virtual void SetTimestampUpdatedHandler(
+      const TimestampUpdatedHandler& timestamp_updated_handler) override {
+    timestamp_updated_handler_ = timestamp_updated_handler;
+  }
+
+  void OnTimer() {
+    base::Time now_time = base::Time::Now();

[dtapuska, 2015/02/18 13:59:12]

I don't get why we are using the wall clock anywhere... Wall clock is subject to
offset and adjustment by other processes.

[varkha, 2015/02/18 18:21:17]

Right. For now this is just a stub implementation to allow debugging although we
could wire that to the ptp and maybe implement software sync this way.

+    base::TimeTicks now_ticks = base::TimeTicks::Now();
+    uint64 fake_beacon_timestamp = now_time.ToInternalValue();
+    uint64 fake_mac_timestamp = now_ticks.ToInternalValue();
+    timestamp_updated_handler_.Run(fake_beacon_timestamp, fake_mac_timestamp);
+  }
+
+ private:
+  TimestampUpdatedHandler timestamp_updated_handler_;
+  base::WeakPtrFactory<MetronomeClientStubImpl> weak_ptr_factory_;

[dtapuska, 2015/02/18 13:59:12]

I thought Weak Ptr Factories should be listed towards the end of the class so
they are destructed first.

[varkha, 2015/02/18 18:21:17]

Done.

+  base::Timer timer_;
+
+  DISALLOW_COPY_AND_ASSIGN(MetronomeClientStubImpl);
+};
+
+}  // namespace
+
+////////////////////////////////////////////////////////////////////////////////
+
+MetronomeClient::MetronomeClient() {
+}
+
+MetronomeClient::~MetronomeClient() {
+}
+
+// static
+MetronomeClient* MetronomeClient::Create(DBusClientImplementationType type) {
+  //  if (type == REAL_DBUS_CLIENT_IMPLEMENTATION)
+  //    return new MetronomeClientImpl();
+  //
+  //  DCHECK_EQ(STUB_DBUS_CLIENT_IMPLEMENTATION, type);
+  return new MetronomeClientStubImpl();
+}
+
+}  // namespace chromeos