#pragma once

#include "envoy/common/pure.h"

#include "envoy/event/dispatcher.h"

#include "envoy/server/watchdog.h"

namespace Envoy {

namespace Server {

/**

 * The GuardDog runs a background thread which scans a number of shared WatchDog

 * objects periodically to verify that they have been recently touched. If some

 * of the watched items have not responded the GuardDog will take action ranging

 * from stats counter increments to killing the entire process (if a deadlock is

 * suspected).

 *

 * The lifespan of the GuardDog thread is tied to the lifespan of this object.

 */

class GuardDog {

public:

  /**

   * Get a WatchDog object pointer to a new WatchDog.

   *

   * After this method returns the WatchDog object must be touched periodically

   * to avoid triggering the GuardDog. If no longer needed use the

   * stopWatching() method to remove it from the list of watched objects.

   *

   * @param thread_id a Thread::ThreadId containing the system thread id

   * @param thread_name supplies the name of the thread which is used for per-thread miss stats.

   * @param dispatcher dispatcher responsible for petting the watchdog.

   */

  virtual WatchDogSharedPtr createWatchDog(Thread::ThreadId thread_id,

                                           const std::string& thread_name,

                                           Event::Dispatcher& dispatcher) PURE;

  /**

   * Tell the GuardDog to forget about this WatchDog.

   * After calling this method it is no longer necessary to touch the WatchDog

   * object.

   *

   * @param wd A WatchDogSharedPtr obtained from createWatchDog.

   */

  virtual void stopWatching(WatchDogSharedPtr wd) PURE;

};

} // namespace Server

} // namespace Envoy