device/udev_linux/udev_watcher.h

// Copyright 2017 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_UDEV_LINUX_UDEV_WATCHER_H_
#define DEVICE_UDEV_LINUX_UDEV_WATCHER_H_

#include <memory>

#include "base/files/file_descriptor_watcher_posix.h"
#include "base/macros.h"
#include "base/sequence_checker.h"
#include "device/udev_linux/scoped_udev.h"

namespace device {

// This class wraps an instance of udev_monitor, watching for devices that are
// added and removed from the system. This class has sequence affinity.
class UdevWatcher {
 public:
  class Observer {
   public:
    virtual ~Observer();
    virtual void OnDeviceAdded(ScopedUdevDevicePtr device);
    virtual void OnDeviceRemoved(ScopedUdevDevicePtr device);
  };

  static std::unique_ptr<UdevWatcher> StartWatching(Observer* observer);

  ~UdevWatcher();

  // Synchronously enumerates the all devices known to udev, calling
  // OnDeviceAdded on the provided Observer for each.
  void EnumerateExistingDevices();

 private:
  UdevWatcher(ScopedUdevPtr udev,
              ScopedUdevMonitorPtr udev_monitor,
              int monitor_fd,
              Observer* observer);

  void OnMonitorReadable();

  ScopedUdevPtr udev_;
  ScopedUdevMonitorPtr udev_monitor_;
  Observer* observer_;
  std::unique_ptr<base::FileDescriptorWatcher::Controller> file_watcher_;
  base::SequenceChecker sequence_checker_;

  DISALLOW_COPY_AND_ASSIGN(UdevWatcher);
};

}  // namespace device

#endif  // DEVICE_UDEV_LINUX_UDEV_WATCHER_H_