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// 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.
#ifndef DEVICE_USB_USB_SERVICE_H_
#define DEVICE_USB_USB_SERVICE_H_
#include <memory>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include "base/bind_helpers.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/observer_list.h"
#include "base/sequenced_task_runner.h"
#include "base/single_thread_task_runner.h"
#include "base/task_scheduler/task_traits.h"
#include "base/threading/non_thread_safe.h"
namespace device {
class UsbDevice;
// The USB service handles creating and managing an event handler thread that is
// used to manage and dispatch USB events. It is also responsible for device
// discovery on the system, which allows it to re-use device handles to prevent
// competition for the same USB device.
class UsbService : public base::NonThreadSafe {
public:
using GetDevicesCallback =
base::Callback<void(const std::vector<scoped_refptr<UsbDevice>>&)>;
class Observer {
public:
virtual ~Observer();
// These events are delivered from the thread on which the UsbService object
// was created.
virtual void OnDeviceAdded(scoped_refptr<UsbDevice> device);
virtual void OnDeviceRemoved(scoped_refptr<UsbDevice> device);
// For observers that need to process device removal after others have run.
// Should not depend on any other service's knowledge of connected devices.
virtual void OnDeviceRemovedCleanup(scoped_refptr<UsbDevice> device);
// Notifies the observer that the UsbService it depends on is shutting down.
virtual void WillDestroyUsbService();
};
// These task traits are to be used for posting blocking tasks to the task
// scheduler.
static constexpr base::TaskTraits kBlockingTaskTraits = {
base::MayBlock(), base::TaskPriority::USER_VISIBLE,
base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN};
// Returns nullptr when initialization fails.
static std::unique_ptr<UsbService> Create();
// Creates a SequencedTaskRunner with kBlockingTaskTraits.
static scoped_refptr<base::SequencedTaskRunner> CreateBlockingTaskRunner();
virtual ~UsbService();
scoped_refptr<UsbDevice> GetDevice(const std::string& guid);
// Enumerates available devices.
virtual void GetDevices(const GetDevicesCallback& callback);
void AddObserver(Observer* observer);
void RemoveObserver(Observer* observer);
// Methods to add and remove devices for testing purposes. Only a device added
// by this method can be removed by RemoveDeviceForTesting().
void AddDeviceForTesting(scoped_refptr<UsbDevice> device);
void RemoveDeviceForTesting(const std::string& device_guid);
void GetTestDevices(std::vector<scoped_refptr<UsbDevice>>* devices);
protected:
UsbService(scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
void NotifyDeviceAdded(scoped_refptr<UsbDevice> device);
void NotifyDeviceRemoved(scoped_refptr<UsbDevice> device);
const scoped_refptr<base::SingleThreadTaskRunner>& task_runner() const {
return task_runner_;
}
const scoped_refptr<base::SequencedTaskRunner>& blocking_task_runner() const {
return blocking_task_runner_;
}
std::unordered_map<std::string, scoped_refptr<UsbDevice>>& devices() {
return devices_;
}
private:
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
std::unordered_map<std::string, scoped_refptr<UsbDevice>> devices_;
std::unordered_set<std::string> testing_devices_;
base::ObserverList<Observer, true> observer_list_;
DISALLOW_COPY_AND_ASSIGN(UsbService);
};
} // namespace device
#endif // DEVICE_USB_USB_SERVICE_H_
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