WatchdogThread Class Reference

#include </builds/gaudi/Gaudi/GaudiKernel/include/GaudiKernel/WatchdogThread.h>

Collaboration diagram for WatchdogThread:

Public Types
using	clock = std::chrono::system_clock
using	time_point = std::chrono::time_point< clock >

Public Member Functions
	WatchdogThread (std::chrono::seconds timeout, bool autostart=false)
	Constructor. More...
virtual	~WatchdogThread ()
	Destructor. More...
void	start ()
	Start the watchdog thread. More...
void	stop ()
	Signal the watchdog thread to stop and wait for it. More...
void	ping ()
	Function to call to notify the watchdog thread that we are still alive. More...
void	setTimeout (std::chrono::seconds timeout)
	Change the duration of the time-out. More...
std::chrono::seconds	getTimeout () const
	Get the current time-out value. More...
time_point	getLastPing () const
	Get the time of latest ping. More...

Protected Member Functions
virtual void	action ()
	User implemented function that will be called if the time-out is reached. More...
virtual void	onPing ()
	User implemented function that will be called when ping is called. More...
virtual void	onStart ()
	User implemented function that will be called when starting. More...
virtual void	onStop ()
	User implemented function that will be called when stopping. More...

Private Attributes
std::chrono::seconds	m_timeout
	Number of seconds allowed between pings. More...
std::atomic< time_point >	m_lastPing
	When the last ping was received. More...
std::thread	m_thread
	Running thread;. More...
std::promise< void >	m_stop_thread
	Flag to mark the thread as running/stopped (avoid possible race conditions). More...

Detailed Description

Simple class for asynchronous check of time-out.

The user must provide a callable with the action to be performed when the time-out occurs.

Author

Marco Clemencic

Date

2010-02-23

Definition at line 27 of file WatchdogThread.h.

Member Typedef Documentation

clock

using WatchdogThread::clock = std::chrono::system_clock

Definition at line 29 of file WatchdogThread.h.

time_point

using WatchdogThread::time_point = std::chrono::time_point<clock>

Definition at line 30 of file WatchdogThread.h.

Constructor & Destructor Documentation

WatchdogThread()

WatchdogThread::WatchdogThread	(	std::chrono::seconds	timeout,
		bool	autostart = false
	)

Constructor.

Definition at line 18 of file WatchdogThread.cpp.

                                                                         : m_timeout( std::move( timeout ) ) {
  // Start the thread immediately if requested.
  if ( autostart ) start();
}

~WatchdogThread()

WatchdogThread::~WatchdogThread ( )

virtual

Destructor.

Definition at line 23 of file WatchdogThread.cpp.

                                {
  // Make sure the thread is stopped before exiting.
  stop();
}

Member Function Documentation

action()

void WatchdogThread::action ( )

protectedvirtual

User implemented function that will be called if the time-out is reached.

Definition at line 70 of file WatchdogThread.cpp.

{}

getLastPing()

time_point WatchdogThread::getLastPing ( ) const

inline

Get the time of latest ping.

Definition at line 61 of file WatchdogThread.h.

{ return m_lastPing.load(); }

getTimeout()

std::chrono::seconds WatchdogThread::getTimeout ( ) const

inline

Get the current time-out value.

Definition at line 58 of file WatchdogThread.h.

{ return m_timeout; }

onPing()

void WatchdogThread::onPing ( )

protectedvirtual

User implemented function that will be called when ping is called.

Definition at line 73 of file WatchdogThread.cpp.

{}

onStart()

void WatchdogThread::onStart ( )

protectedvirtual

User implemented function that will be called when starting.

Definition at line 76 of file WatchdogThread.cpp.

{}

onStop()

void WatchdogThread::onStop ( )

protectedvirtual

User implemented function that will be called when stopping.

Definition at line 79 of file WatchdogThread.cpp.

{}

ping()

void WatchdogThread::ping ( )

inline

Function to call to notify the watchdog thread that we are still alive.

Definition at line 49 of file WatchdogThread.h.

                     {
    m_lastPing.store( clock::now() );
    onPing();
  }

setTimeout()

void WatchdogThread::setTimeout ( std::chrono::seconds  timeout )

inline

Change the duration of the time-out.

Definition at line 55 of file WatchdogThread.h.

{ m_timeout = timeout; }

start()

void WatchdogThread::start

(

)

Start the watchdog thread.

Definition at line 28 of file WatchdogThread.cpp.

                           {
  if ( !m_thread.joinable() ) { // can be started only if the thread is not yet started
    // call user-defined function
    onStart();
    // Initialize the first "last ping"
    ping();
    // Start a new thread telling it to call the member function i_run()
    m_thread = std::thread{ [this, is_stopped = m_stop_thread.get_future()]() {
      // Copy of the last ping
      auto lastPing = getLastPing();
 
      // set initial check time
      auto nextCheck = lastPing + getTimeout();
 
      // enter infinite loop
      // Wait until the next check point time is reached.
      while ( is_stopped.wait_until( nextCheck ) == std::future_status::timeout ) {
        // Check if there was a ping while we were sleeping
        if ( lastPing == getLastPing() ) { // no further accesses
          action();
          // schedule the next check for now + dt (seems a good estimate)
          nextCheck = clock::now() + getTimeout();
        } else { // there was a ping
          // schedule the next check for last_access + dt
          lastPing  = getLastPing();
          nextCheck = lastPing + getTimeout();
        }
      }
    } };
  }
}

stop()

void WatchdogThread::stop

(

)

Signal the watchdog thread to stop and wait for it.

Definition at line 60 of file WatchdogThread.cpp.

                          {
  if ( m_thread.joinable() ) {
    m_stop_thread.set_value(); // tell the thread to stop
    m_thread.join();           // wait for it
    // call user-defined function
    onStop();
  }
}

Member Data Documentation

m_lastPing

std::atomic<time_point> WatchdogThread::m_lastPing

private

When the last ping was received.

Definition at line 81 of file WatchdogThread.h.

m_stop_thread

std::promise<void> WatchdogThread::m_stop_thread

private

Flag to mark the thread as running/stopped (avoid possible race conditions).

Definition at line 87 of file WatchdogThread.h.

m_thread

std::thread WatchdogThread::m_thread

private

Running thread;.

Definition at line 84 of file WatchdogThread.h.

m_timeout

std::chrono::seconds WatchdogThread::m_timeout

private

Number of seconds allowed between pings.

Definition at line 78 of file WatchdogThread.h.

---

The documentation for this class was generated from the following files:

• GaudiKernel/include/GaudiKernel/WatchdogThread.h
• GaudiKernel/src/Lib/WatchdogThread.cpp