components/input/timeout_monitor.h

// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_INPUT_TIMEOUT_MONITOR_H_
#define COMPONENTS_INPUT_TIMEOUT_MONITOR_H_

#include "base/functional/callback.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "base/component_export.h"

namespace input {

// Utility class for handling a timeout callback with periodic starts and stops.
class COMPONENT_EXPORT(INPUT) TimeoutMonitor {
 public:
  typedef base::RepeatingClosure TimeoutHandler;
  // |task_runner| must run tasks on the same sequence which TimeoutMonitor is
  // constructed on.
  explicit TimeoutMonitor(const TimeoutHandler& timeout_handler,
                          scoped_refptr<base::SequencedTaskRunner> task_runner);

  TimeoutMonitor(const TimeoutMonitor&) = delete;
  TimeoutMonitor& operator=(const TimeoutMonitor&) = delete;

  ~TimeoutMonitor();

  // Schedule the timeout timer to fire at |delay| into the future. If a timeout
  // has already been scheduled, reschedule only if |delay| is sooner than the
  // currently scheduled timeout time.
  void Start(base::TimeDelta delay);

  void Restart(base::TimeDelta delay);
  void Stop();
  bool IsRunning() const;

  base::TimeDelta GetCurrentDelay();

 private:
  void StartImpl(base::TimeDelta delay);
  void CheckTimedOut();

  TimeoutHandler timeout_handler_;

  // Indicates a time in the future when we would consider the input as
  // having timed out, if it does not receive an appropriate stop request.
  base::TimeTicks time_when_considered_timed_out_;

  // This timer runs to check if |time_when_considered_timed_out_| has past.
  base::OneShotTimer timeout_timer_;
};

}  // namespace input

#endif  // COMPONENTS_INPUT_TIMEOUT_MONITOR_H_