Battery Status API: implementation for Linux.

content/browser/battery_status/battery_status_manager_linux.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/battery_status/battery_status_manager_linux.h"
+
+#include "base/macros.h"
+#include "base/threading/thread.h"
+#include "base/values.h"
+#include "content/public/browser/browser_thread.h"
+#include "dbus/bus.h"
+#include "dbus/message.h"
+#include "dbus/object_path.h"
+#include "dbus/object_proxy.h"
+#include "dbus/values_util.h"
+#include "third_party/WebKit/public/platform/WebBatteryStatus.h"
+
+namespace content {
+
+namespace {
+
+const char kUPowerServiceName[] = "org.freedesktop.UPower";
+const char kUPowerDeviceName[] = "org.freedesktop.UPower.Device";
+const char kUPowerPath[] = "/org/freedesktop/UPower";
+const char kUPowerDeviceSignalChanged[] = "Changed";
+const char kBatteryWatcherThreadName[] = "BatteryStatusWatcher";
+const char kDBusPropertiesInterface[] = "org.freedesktop.DBus.Properties";
+const char kDBusPropertiesGetAll[] = "GetAll";
+
+// intended for unit32, int64, uint64, double.

[Michael van Ouwerkerk, 2014/08/08 14:54:59]

s/unit32/uint32/

[timvolodine, 2014/08/08 18:46:45]

Done.

+template<typename T>
+T GetProperty(const base::DictionaryValue& dictionary,
+              const std::string& property_name,
+              T default_value) {
+  double value;
+  return dictionary.GetDouble(property_name, &value) ? value : default_value;

[stevenjb, 2014/08/08 16:18:16]

static_cast<T>(value)

[timvolodine, 2014/08/08 18:46:45]

Done.

+}
+
+// bool
+template<>
+bool GetProperty(const base::DictionaryValue& dictionary,
+                 const std::string& property_name,
+                 bool default_value) {
+  bool value;
+  return dictionary.GetBoolean(property_name, &value) ? value : default_value;
+}
+
+scoped_ptr<base::DictionaryValue> GetPropertiesAsDictionary(
+    dbus::ObjectProxy* proxy) {
+  dbus::MethodCall method_call(kDBusPropertiesInterface,
+                               kDBusPropertiesGetAll);
+  dbus::MessageWriter builder(&method_call);
+  builder.AppendString(kUPowerDeviceName);
+
+  scoped_ptr<dbus::Response> response(
+      proxy->CallMethodAndBlock(&method_call,
+                                dbus::ObjectProxy::TIMEOUT_USE_DEFAULT));
+  if (response) {

[stevenjb, 2014/08/08 16:18:16]

We should probably return NULL on failure to read the property and handle that
in the callers. Also, early exit if !response.

[timvolodine, 2014/08/08 18:46:45]

the idea here is to return an empty dictionary, which does not cause special
cases like NULL later.
early exit does not look possible because of another if later on.

+    dbus::MessageReader reader(response.get());
+    scoped_ptr<base::Value> value(dbus::PopDataAsValue(&reader));
+    base::DictionaryValue* dictionary_value = NULL;
+    if (value && value->GetAsDictionary(&dictionary_value)) {
+      ignore_result(value.release());
+      return scoped_ptr<base::DictionaryValue>(dictionary_value);
+    }
+  }
+  return scoped_ptr<base::DictionaryValue>(new base::DictionaryValue());
+}
+
+void GetPowerSourcesPaths(dbus::ObjectProxy* proxy,
+                          std::vector<dbus::ObjectPath>& paths) {
+  if (!proxy)
+    return;
+
+  dbus::MethodCall method_call(kUPowerServiceName, "EnumerateDevices");
+  scoped_ptr<dbus::Response> response(proxy->CallMethodAndBlock(&method_call,
+      dbus::ObjectProxy::TIMEOUT_USE_DEFAULT));
+
+  if (response) {
+    dbus::MessageReader reader(response.get());
+    if (reader.PopArrayOfObjectPaths(&paths))
+      return;
+  }
+  paths.clear();
+}
+
+class BatteryStatusNotificationThread : public base::Thread {
+ public:
+  BatteryStatusNotificationThread(
+      const BatteryStatusService::BatteryUpdateCallback& callback)
+      : base::Thread(kBatteryWatcherThreadName),
+        callback_(callback),
+        battery_proxy_(0) {}
+
+  virtual ~BatteryStatusNotificationThread() {
+    if (system_bus_)
+      ShutdownDBusConnection();
+    Stop();
+  }
+
+  void StartListening() {
+    DCHECK(OnWatcherThread());
+
+    if (system_bus_)
+      return;
+
+    InitDBus();
+    dbus::ObjectProxy* power_proxy =
+        system_bus_->GetObjectProxy(kUPowerServiceName,
+                                    dbus::ObjectPath(kUPowerPath));
+    std::vector<dbus::ObjectPath> device_paths;
+    GetPowerSourcesPaths(power_proxy, device_paths);
+
+    for (size_t i = 0; i < device_paths.size(); ++i) {
+      const dbus::ObjectPath& device_path = device_paths[i];
+      dbus::ObjectProxy* device_proxy = system_bus_->GetObjectProxy(
+          kUPowerServiceName, device_path);
+      scoped_ptr<base::DictionaryValue> dictionary =
+          GetPropertiesAsDictionary(device_proxy);
+
+      bool is_present = GetProperty<bool>(*dictionary, "IsPresent", false);
+      uint32 type = GetProperty<uint32>(*dictionary, "Type", 0);
+
+      if (is_present && type == 2 /* battery */) {

[mlamouri (slow - plz ping), 2014/08/07 16:17:04]

Could you add an enum for that too? Sorry for not catching it before.

[stevenjb, 2014/08/08 16:18:16]

nit: if (!is_present || type != TYPE_BATTERY) continue;

[timvolodine, 2014/08/08 18:46:45]

Done.

[timvolodine, 2014/08/08 18:46:45]

Done.

+        if (battery_proxy_) {
+          // TODO(timvolodine): add support for multiple batteries. Currently we
+          // only collect information from the first battery we encounter
+          // (crbug.com/400780).
+          // TODO(timvolodine): add UMA logging for this case.
+          LOG(WARNING) << "multiple batteries found, "
+                       << "using status data of the first battery only.";
+        } else {
+          battery_proxy_ = device_proxy;
+        }
+      }
+    }
+
+    if (!battery_proxy_) {
+      callback_.Run(blink::WebBatteryStatus());
+      return;
+    }
+
+    battery_proxy_->ConnectToSignal(
+        kUPowerDeviceName,
+        kUPowerDeviceSignalChanged,
+        base::Bind(&BatteryStatusNotificationThread::BatteryChanged,
+                   base::Unretained(this)),
+        base::Bind(&BatteryStatusNotificationThread::OnSignalConnected,
+                   base::Unretained(this)));
+  }
+
+  void StopListening() {
+    DCHECK(OnWatcherThread());
+
+    if (!system_bus_)
+      return;
+
+    ShutdownDBusConnection();
+  }
+
+ private:
+
+  bool OnWatcherThread() {
+    return std::string(base::PlatformThread::GetName()).compare(
+        kBatteryWatcherThreadName) == 0;
+  }
+
+  void InitDBus() {
+    DCHECK(OnWatcherThread());
+
+    dbus::Bus::Options options;
+    options.bus_type = dbus::Bus::SYSTEM;
+    options.connection_type = dbus::Bus::PRIVATE;
+    system_bus_ = new dbus::Bus(options);
+  }
+
+  void ShutdownDBusConnection() {
+    // Shutdown DBus connection later because there may be pending tasks on
+    // this thread.
+    message_loop()->PostTask(FROM_HERE,
+                             base::Bind(&dbus::Bus::ShutdownAndBlock,
+                                        system_bus_));
+    system_bus_ = 0;
+    battery_proxy_ = 0;
+  }
+
+  void OnSignalConnected(const std::string& interface_name,
+                         const std::string& signal_name,
+                         bool success) {
+    DCHECK(OnWatcherThread());
+
+    if (interface_name.compare(kUPowerDeviceName) != 0 ||
+        signal_name.compare(kUPowerDeviceSignalChanged) != 0) {
+      return;
+    }
+
+    if (!system_bus_)
+      return;
+
+    if (success) {
+      BatteryChanged(0);
+    } else {
+      // Failed to register for "Changed" signal, execute callback with the
+      // default values.
+      callback_.Run(blink::WebBatteryStatus());
+    }
+  }
+
+  void BatteryChanged(dbus::Signal* signal /* unsused */) {
+    DCHECK(OnWatcherThread());
+    blink::WebBatteryStatus status;
+    scoped_ptr<base::DictionaryValue> dictionary =
+        GetPropertiesAsDictionary(battery_proxy_);
+    ComputeWebBatteryStatus(*dictionary, status);
+    callback_.Run(status);

[mlamouri (slow - plz ping), 2014/08/07 16:17:04]

This block needs some empty lines. It's quite dense.

[timvolodine, 2014/08/08 18:46:45]

Done.

+  }
+
+  BatteryStatusService::BatteryUpdateCallback callback_;
+  scoped_refptr<dbus::Bus> system_bus_;
+  dbus::ObjectProxy* battery_proxy_;  // owned by dbus
+
+  DISALLOW_COPY_AND_ASSIGN(BatteryStatusNotificationThread);
+};
+
+class BatteryStatusManagerLinux : public BatteryStatusManager {
+ public:
+  explicit BatteryStatusManagerLinux(
+      const BatteryStatusService::BatteryUpdateCallback& callback)
+      : callback_(callback) {}
+
+  virtual ~BatteryStatusManagerLinux() {}
+
+ private:
+  // BatteryStatusManager:
+  virtual bool StartListeningBatteryChange() OVERRIDE {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+    if (!notifier_thread_) {
+      base::Thread::Options thread_options(base::MessageLoop::TYPE_IO, 0);
+      notifier_thread_.reset(new BatteryStatusNotificationThread(callback_));
+      if (!notifier_thread_->StartWithOptions(thread_options)) {
+        notifier_thread_.reset();
+        LOG(ERROR) << "Could not start the " << kBatteryWatcherThreadName
+                   << "thread";
+        return false;
+      }
+    }

[stevenjb, 2014/08/08 16:18:16]

This bit should probably be moved to a helper method, e.g.
if (!NotifierThreadStarted())
  return false;

[timvolodine, 2014/08/08 18:46:45]

Done.

+
+    notifier_thread_->message_loop()->PostTask(
+        FROM_HERE,
+        base::Bind(&BatteryStatusNotificationThread::StartListening,
+                   base::Unretained(notifier_thread_.get())));
+    return true;
+  }
+
+  virtual void StopListeningBatteryChange() OVERRIDE {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+    notifier_thread_->message_loop()->PostTask(
+        FROM_HERE,
+        base::Bind(&BatteryStatusNotificationThread::StopListening,
+                   base::Unretained(notifier_thread_.get())));
+  }
+
+  BatteryStatusService::BatteryUpdateCallback callback_;
+  scoped_ptr<BatteryStatusNotificationThread> notifier_thread_;
+
+  DISALLOW_COPY_AND_ASSIGN(BatteryStatusManagerLinux);
+};
+
+}  // namespace
+
+// Computes and sets the WebBatteryStatus values where possible based on the
+// passed dictionary.
+void ComputeWebBatteryStatus(const base::DictionaryValue& dictionary,
+                             blink::WebBatteryStatus& status) {
+  if (!dictionary.HasKey("State"))
+    return;
+  uint32 state = GetProperty<uint32>(dictionary, "State",
+                                     UPOWER_DEVICE_STATE_UNKNOWN);
+  status.charging = state != UPOWER_DEVICE_STATE_DISCHARGING;
+  double percentage = GetProperty<double>(dictionary, "Percentage", 100);
+  // Convert percentage to a value between 0 and 1 with 3 digits of precision.
+  status.level = round(percentage * 10) / 1000.f;

[mlamouri (slow - plz ping), 2014/08/07 16:17:04]

Could you add a test with "Percentage" = 13.37 and check that it is rounded to
"0.113".

[timvolodine, 2014/08/08 18:46:45]

Done.

+
+  switch (state) {
+    case UPOWER_DEVICE_STATE_CHARGING : {
+      int64 time_to_full = GetProperty<int64>(dictionary, "TimeToFull", 0);
+      status.chargingTime =
+          (time_to_full > 0) ? time_to_full
+                             : std::numeric_limits<double>::infinity();
+      break;
+    }
+    case UPOWER_DEVICE_STATE_DISCHARGING : {
+      int64 time_to_empty = GetProperty<int64>(dictionary, "TimeToEmpty", 0);
+      // Set dischargingTime if it's available. Otherwise leave the default
+      // value which is +infinity.
+      if (time_to_empty > 0)
+        status.dischargingTime = time_to_empty;
+      status.chargingTime = std::numeric_limits<double>::infinity();
+      break;
+    }
+    case UPOWER_DEVICE_STATE_FULL : {
+      break;
+    }
+    default: {
+      status.chargingTime = std::numeric_limits<double>::infinity();
+    }
+  }
+}
+
+// static
+scoped_ptr<BatteryStatusManager> BatteryStatusManager::Create(
+    const BatteryStatusService::BatteryUpdateCallback& callback) {
+  return scoped_ptr<BatteryStatusManager>(
+      new BatteryStatusManagerLinux(callback));
+}
+
+}  // namespace content