text: /*
   * Copyright 2018- The Pixie Authors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   * SPDX-License-Identifier: Apache-2.0
   */
  
  #pragma once
  
  #include <chrono>
  #include <functional>
  #include <memory>
  
  namespace px {
  namespace event {
  /**
   * Callback for timer after expiration.
   */
  using TimerCB = std::function<void()>;
  
  /**
   * Timer is an abstract timer event.
   */
  class Timer {
   public:
    virtual ~Timer() = default;
  
    /**
     * Disable pending timeout without destroying the timer.
     */
    virtual void DisableTimer() = 0;
  
    /**
     * Enable a pending timeout. If a timeout is already pending, it will be reset to the new timeout.
     * @param ms supplies the duration of the alarm in milliseconds.
     */
    virtual void EnableTimer(const std::chrono::milliseconds& ms) = 0;
  
    /**
     * Return whether the timer is currently armed.
     */
    virtual bool Enabled() = 0;
  };
  
  using TimerUPtr = std::unique_ptr<Timer>;
  
  }  // namespace event
  }  // namespace px
  