[sensors](CrOS/Linux) Implement Sensor device manager for sensors

device/generic_sensor/platform_sensor_manager_linux.cc

+// Copyright 2016 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 "device/generic_sensor/platform_sensor_manager_linux.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "device/generic_sensor/linux/platform_sensor_reader_linux.h"
+#include "device/generic_sensor/linux/sensor_data_linux.h"
+#include "device/generic_sensor/platform_sensor_provider_linux.h"
+
+namespace device {
+
+namespace {
+
+std::string StringOrEmptyIfNull(const char* value) {
+  return value ? value : std::string();
+}
+
+}  // namespace
+
+SensorDeviceLinux::SensorDeviceLinux(
+    const std::string& sensor_device_node,
+    double sensor_device_frequency,
+    double sensor_device_scaling_value,
+    double sensor_device_offset_value,
+    mojom::ReportingMode mode,
+    SensorDataLinux::ReaderFunctor scaling_func,
+    std::vector<base::FilePath> device_reading_files)
+    : device_node(sensor_device_node),
+      device_frequency(sensor_device_frequency),
+      device_scaling_value(sensor_device_scaling_value),
+      device_offset_value(sensor_device_offset_value),
+      reporting_mode(mode),
+      apply_scaling_func(scaling_func),
+      device_reading_files(std::move(device_reading_files)) {}
+
+SensorDeviceLinux::~SensorDeviceLinux() = default;
+
+SensorDeviceService::SensorDeviceService(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+    : observer_(this), manager_(nullptr), task_runner_(task_runner) {

[Mikhail, 2016/11/30 12:29:36]

nit: move(task_runner)

[maksims (do not use this acc), 2016/12/05 13:06:59]

not needed any more.

+  thread_checker_.DetachFromThread();
+}
+
+SensorDeviceService::~SensorDeviceService() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void SensorDeviceService::Start(
+    base::WeakPtr<SensorDeviceManager> manager,
+    SensorDeviceManager::OnDeviceAddedCallback device_added_callback,
+    SensorDeviceManager::OnDeviceRemovedCallback device_removed_callback) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  manager_ = manager;
+  device_added_callback_ = device_added_callback;
+  device_removed_callback_ = device_removed_callback;
+
+  DeviceMonitorLinux* monitor = DeviceMonitorLinux::GetInstance();
+  observer_.Add(monitor);
+  monitor->Enumerate(
+      base::Bind(&SensorDeviceService::OnDeviceAdded, base::Unretained(this)));
+
+  task_runner_->PostTask(

[Mikhail, 2016/11/30 12:29:36]

could be done on upper call frame

+      FROM_HERE,
+      base::Bind(&SensorDeviceManager::SetEnumerationReady, manager_));
+}
+
+std::string SensorDeviceService::UdevDeviceGetSubsystem(udev_device* dev) {

[Mikhail, 2016/11/30 12:29:36]

nit: Get..

[maksims (do not use this acc), 2016/12/05 13:06:59]

Done.

+  return StringOrEmptyIfNull(udev_device_get_subsystem(dev));
+}
+
+std::string SensorDeviceService::UdevDeviceGetSyspath(udev_device* dev) {
+  return StringOrEmptyIfNull(udev_device_get_syspath(dev));
+}
+
+std::string SensorDeviceService::UdevDeviceGetSysattrValue(
+    udev_device* dev,
+    const std::string& attribute) {
+  return StringOrEmptyIfNull(
+      udev_device_get_sysattr_value(dev, attribute.c_str()));
+}
+
+std::string SensorDeviceService::UdevDeviceGetDevnode(udev_device* dev) {
+  return StringOrEmptyIfNull(udev_device_get_devnode(dev));
+}
+
+void SensorDeviceService::OnDeviceAdded(udev_device* dev) {
+  const std::string subsystem = UdevDeviceGetSubsystem(dev);
+  if (subsystem.empty() || strcmp(subsystem.c_str(), "iio") != 0)

[Mikhail, 2016/11/30 12:29:36]

subsystem.compare()

[maksims (do not use this acc), 2016/12/05 13:06:59]

Done.

+    return;
+
+  const std::string sysfs_path = UdevDeviceGetSyspath(dev);
+  if (sysfs_path.empty())
+    return;
+
+  const std::string device_node = UdevDeviceGetDevnode(dev);
+  if (device_node.empty())
+    return;
+
+  const uint32_t first = static_cast<uint32_t>(mojom::SensorType::FIRST);
+  const uint32_t last = static_cast<uint32_t>(mojom::SensorType::LAST);
+  for (uint32_t i = first; i < last; ++i) {
+    SensorDataLinux data;
+    mojom::SensorType type = static_cast<mojom::SensorType>(i);
+    if (!InitSensorData(type, &data)) {
+      continue;
+    }
+
+    std::vector<base::FilePath> sensor_file_names;
+    for (auto const& names : data.sensor_file_names) {
+      for (auto const& name : names) {
+        const std::string value = UdevDeviceGetSysattrValue(dev, name.c_str());
+        if (value.empty())
+          continue;
+        base::FilePath full_path = base::FilePath(sysfs_path).Append(name);
+        sensor_file_names.push_back(full_path);
+        break;
+      }
+    }
+
+    if (sensor_file_names.empty())
+      continue;
+
+    const std::string scaling_value =
+        UdevDeviceGetSysattrValue(dev, data.sensor_scale_name.c_str());
+    // If scaling value is not found, treat it as 1.
+    double sensor_scaling_value = 1;
+    if (!scaling_value.empty())
+      base::StringToDouble(scaling_value, &sensor_scaling_value);
+
+    const std::string offset_vallue =
+        UdevDeviceGetSysattrValue(dev, data.sensor_offset_file_name.c_str());
+    // If offset value is not found, treat it as 0.
+    double sensor_offset_value = 0;
+    if (!offset_vallue.empty())
+      base::StringToDouble(offset_vallue, &sensor_offset_value);
+
+    const std::string frequency_value =
+        UdevDeviceGetSysattrValue(dev, data.sensor_frequency_file_name.c_str());
+    // If frequency is not found, use default one from SensorDataLinux struct.
+    double sensor_frequency_value = data.default_configuration.frequency();
+    // By default, |reporting_mode| is ON_CHANGE. But if platform provides
+    // sampling frequency, the reporting mode is CONTINUOUS.
+    mojom::ReportingMode reporting_mode = mojom::ReportingMode::ON_CHANGE;
+    if (!frequency_value.empty()) {
+      base::StringToDouble(frequency_value, &sensor_frequency_value);
+      reporting_mode = mojom::ReportingMode::CONTINUOUS;
+    }
+
+    // One |dev| can represent more than one sensor.
+    // For example, there is an accelerometer and gyroscope represented by one
+    // |dev| in Chrome OS, kernel < 3.18. Thus, iterate through all possible
+    // types of sensors.
+    std::unique_ptr<SensorDeviceLinux> device(new SensorDeviceLinux(
+        device_node, sensor_frequency_value, sensor_scaling_value,
+        sensor_offset_value, reporting_mode, data.apply_scaling_func,
+        std::move(sensor_file_names)));
+    task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(device_added_callback_, data.type, base::Passed(&device)));
+  }
+}
+
+void SensorDeviceService::OnDeviceRemoved(udev_device* dev) {
+  const char* subsystem = udev_device_get_subsystem(dev);
+  if (!subsystem || strcmp(subsystem, "iio") != 0)
+    return;
+
+  const char* value = udev_device_get_devnode(dev);
+  if (!value)
+    return;
+  const std::string device_node = value;
+
+  const uint32_t first = static_cast<uint32_t>(mojom::SensorType::FIRST);
+  const uint32_t last = static_cast<uint32_t>(mojom::SensorType::LAST);
+  for (uint32_t i = first; i < last; ++i) {

[Mikhail, 2016/11/30 12:29:36]

better to cache sensor nodes instead of running this algorithm again

[maksims (do not use this acc), 2016/12/05 13:06:59]

Done.

+    SensorDataLinux data;
+    mojom::SensorType type = static_cast<mojom::SensorType>(i);
+    if (!InitSensorData(type, &data))
+      continue;
+
+    std::vector<base::FilePath> sensor_file_names;
+    for (auto const& names : data.sensor_file_names) {
+      for (auto const& name : names) {
+        const char* value = udev_device_get_sysattr_value(dev, name.c_str());
+        if (value)
+          break;
+      }
+      break;
+    }
+
+    // One |dev| can represent more than one sensor.
+    // For example, there is an accelerometer and gyroscope represented by one
+    // |dev| in Chrome OS, kernel < 3.18. Thus, iterate through all possible
+    // type of sensors.
+    task_runner_->PostTask(FROM_HERE, base::Bind(device_removed_callback_,
+                                                 data.type, device_node));
+  }
+}
+
+SensorDeviceManager::SensorDeviceManager()
+    : task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      enumeration_ready_(false),
+      sensor_device_service_started_(false),
+      weak_factory_(this) {}
+
+SensorDeviceManager::~SensorDeviceManager() {
+  DCHECK(!sensor_device_service_);
+}
+
+void SensorDeviceManager::Shutdown() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  const bool did_post_task = file_task_runner_->DeleteSoon(
+      FROM_HERE, sensor_device_service_.release());
+  DCHECK(did_post_task);
+  enumeration_ready_ = false;
+  sensor_device_service_started_ = false;
+  sensor_device_map_.clear();
+}
+
+void SensorDeviceManager::GetSensorDevice(
+    mojom::SensorType type,
+    const GetSensorDeviceCallback& callback) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (!InitializeService()) {
+    callback.Run(nullptr);
+    return;
+  }
+  // Enumeration is not ready yet.
+  // Store callbacks and run them when ready.
+  if (!enumeration_ready()) {
+    DCHECK(!base::ContainsKey(get_device_callbacks_, type));
+    get_device_callbacks_[type] = callback;
+    return;
+  }
+  SensorDeviceLinux* device = nullptr;
+  if (base::ContainsKey(sensor_device_map_, type))
+    device = sensor_device_map_[type].get();
+  callback.Run(device);
+}
+
+void SensorDeviceManager::GetAllSensorDevices(
+    const GetSensorDeviceCallback& callback) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  // TODO(maksims): implement this method once we have discovery API.
+  NOTIMPLEMENTED();
+}
+
+void SensorDeviceManager::SetSensorDeviceServiceForTesting(
+    std::unique_ptr<SensorDeviceService> service) {
+  Shutdown();
+  sensor_device_service_ = std::move(service);
+}
+
+void SensorDeviceManager::SetBlockingTaskRunner(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
+  file_task_runner_ = task_runner;
+}
+
+bool SensorDeviceManager::InitializeService() {
+  if (!sensor_device_service_) {
+    sensor_device_service_ =
+        base::MakeUnique<SensorDeviceService>(task_runner_);
+  }
+  if (!sensor_device_service_started_) {
+    OnDeviceAddedCallback device_added_callback = base::Bind(
+        &SensorDeviceManager::OnDeviceAdded, weak_factory_.GetWeakPtr());
+    OnDeviceRemovedCallback device_removed_callback = base::Bind(
+        &SensorDeviceManager::OnDeviceRemoved, weak_factory_.GetWeakPtr());
+
+    SetServiceStarted();
+    return file_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&SensorDeviceService::Start,
+                   base::Unretained(sensor_device_service_.get()),
+                   weak_factory_.GetWeakPtr(), std::move(device_added_callback),
+                   std::move(device_removed_callback)));
+  }
+
+  return sensor_device_service_started_;
+}
+
+void SensorDeviceManager::SetServiceStarted() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(!sensor_device_service_started_);
+  sensor_device_service_started_ = true;
+}
+
+void SensorDeviceManager::OnDeviceAdded(
+    mojom::SensorType type,
+    std::unique_ptr<SensorDeviceLinux> sensor_device) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  // At the moment, we support only one device per type.
+  if (base::ContainsKey(sensor_device_map_, type))
+    return;
+  sensor_device_map_[type] = std::move(sensor_device);
+}
+
+void SensorDeviceManager::OnDeviceRemoved(mojom::SensorType type,
+                                          const std::string& device_node) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  auto it = sensor_device_map_.find(type);
+  if (it == sensor_device_map_.end())
+    return;
+  if (it->second->device_node == device_node)
+    sensor_device_map_.erase(it);
+}
+
+void SensorDeviceManager::SetEnumerationReady() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(!enumeration_ready());
+  enumeration_ready_ = true;
+  TriggerCallbacks();
+}
+
+void SensorDeviceManager::TriggerCallbacks() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  CallbackToTypeMap::iterator cb_it = get_device_callbacks_.begin();

[Mikhail, 2016/11/30 12:29:36]

I think we can avoid caching callbacks here, if introduce API like
"is_initialized()" getter and "initialized()" signal. Callbacks from mojo calls
are already initialized in provider, that should be enough.

[maksims (do not use this acc), 2016/12/05 13:06:59]

As long as I've merged this class with the provider class, would you please
check another version?

+  while (cb_it != get_device_callbacks_.end()) {
+    SensorDeviceLinux* device = nullptr;
+    mojom::SensorType type = cb_it->first;
+    auto dev_it = sensor_device_map_.find(type);
+    if (dev_it != sensor_device_map_.end())
+      device = dev_it->second.get();
+
+    GetSensorDeviceCallback cb = cb_it->second;
+    cb_it->second.Reset();
+    if (!cb.is_null())
+      cb.Run(device);
+    ++cb_it;
+  }
+  get_device_callbacks_.clear();
+}
+
+}  // namespace device