WatchdogThread.h

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* (c) Copyright 1998-2024 CERN for the benefit of the LHCb and ATLAS collaborations *
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* This software is distributed under the terms of the Apache version 2 licence,     *
* copied verbatim in the file "LICENSE".                                            *
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#pragma once
 
#include <GaudiKernel/Kernel.h> // for GAUDI_API
#include <atomic>
#include <chrono>
#include <future>
 
class GAUDI_API WatchdogThread {
public:
  using clock      = std::chrono::system_clock;
  using time_point = std::chrono::time_point<clock>;
 
  //  @param timeout the time span that can occur between two pings.
  //  @param autostart if set to true, the second thread is started automatically
  //                   on construction, otherwise the user have to call start().
  WatchdogThread( std::chrono::seconds timeout, bool autostart = false );
 
  //  Stop the thread if not done earlier.
  virtual ~WatchdogThread();
 
  void start();
 
  void stop();
 
  inline void ping() {
    m_lastPing.store( clock::now() );
    onPing();
  }
 
  inline void setTimeout( std::chrono::seconds timeout ) { m_timeout = timeout; }
 
  inline std::chrono::seconds getTimeout() const { return m_timeout; }
 
  inline time_point getLastPing() const { return m_lastPing.load(); }
 
protected:
  virtual void action();
 
  virtual void onPing();
 
  virtual void onStart();
 
  virtual void onStop();
 
private:
  std::chrono::seconds m_timeout;
 
  std::atomic<time_point> m_lastPing;
 
  std::thread m_thread;
 
  std::promise<void> m_stop_thread;
};