device/sensors/device_sensor_service.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 "device/sensors/device_sensor_service.h"

#include "base/bind.h"
#include "base/logging.h"
#include "base/memory/singleton.h"
#include "base/trace_event/trace_event.h"
#include "device/sensors/data_fetcher_shared_memory.h"

namespace device {

DeviceSensorService::DeviceSensorService()
    : num_motion_readers_(0),
      num_orientation_readers_(0),
      num_orientation_absolute_readers_(0),
      is_shutdown_(false) {
  base::MessageLoop::current()->AddDestructionObserver(this);
}

DeviceSensorService::~DeviceSensorService() {}

DeviceSensorService* DeviceSensorService::GetInstance() {
  return base::Singleton<DeviceSensorService, base::LeakySingletonTraits<
                                                  DeviceSensorService>>::get();
}

void DeviceSensorService::AddConsumer(ConsumerType consumer_type) {
  if (!ChangeNumberConsumers(consumer_type, 1))
    return;

  DCHECK(GetNumberConsumers(consumer_type));

  if (!data_fetcher_)
    data_fetcher_.reset(new DataFetcherSharedMemory);
  data_fetcher_->StartFetchingDeviceData(consumer_type);
}

void DeviceSensorService::RemoveConsumer(ConsumerType consumer_type) {
  if (!ChangeNumberConsumers(consumer_type, -1))
    return;

  if (GetNumberConsumers(consumer_type) == 0)
    data_fetcher_->StopFetchingDeviceData(consumer_type);
}

bool DeviceSensorService::ChangeNumberConsumers(ConsumerType consumer_type,
                                                int delta) {
  DCHECK(thread_checker_.CalledOnValidThread());
  if (is_shutdown_)
    return false;

  switch (consumer_type) {
    case CONSUMER_TYPE_MOTION:
      num_motion_readers_ += delta;
      DCHECK_GE(num_motion_readers_, 0);
      return true;
    case CONSUMER_TYPE_ORIENTATION:
      num_orientation_readers_ += delta;
      DCHECK_GE(num_orientation_readers_, 0);
      return true;
    case CONSUMER_TYPE_ORIENTATION_ABSOLUTE:
      num_orientation_absolute_readers_ += delta;
      DCHECK_GE(num_orientation_absolute_readers_, 0);
      return true;
    default:
      NOTREACHED();
  }
  return false;
}

int DeviceSensorService::GetNumberConsumers(ConsumerType consumer_type) const {
  switch (consumer_type) {
    case CONSUMER_TYPE_MOTION:
      return num_motion_readers_;
    case CONSUMER_TYPE_ORIENTATION:
      return num_orientation_readers_;
    case CONSUMER_TYPE_ORIENTATION_ABSOLUTE:
      return num_orientation_absolute_readers_;
    default:
      NOTREACHED();
  }
  return 0;
}

mojo::ScopedSharedBufferHandle DeviceSensorService::GetSharedMemoryHandle(
    ConsumerType consumer_type) {
  DCHECK(thread_checker_.CalledOnValidThread());
  return data_fetcher_->GetSharedMemoryHandle(consumer_type);
}

void DeviceSensorService::WillDestroyCurrentMessageLoop() {
  base::MessageLoop::current()->RemoveDestructionObserver(this);
  TRACE_EVENT0("shutdown", "DeviceSensorService::Subsystem:SensorService");
  Shutdown();
}

void DeviceSensorService::Shutdown() {
  if (data_fetcher_) {
    data_fetcher_->Shutdown();
    data_fetcher_.reset();
  }
  is_shutdown_ = true;
}

void DeviceSensorService::SetDataFetcherForTesting(
    DataFetcherSharedMemory* test_data_fetcher) {
  if (data_fetcher_)
    data_fetcher_->Shutdown();
  data_fetcher_.reset(test_data_fetcher);
}

}  // namespace device