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Public Member Functions | Protected Member Functions | Private Member Functions | Private Attributes | List of all members
WatchdogThread Class Reference

Simple class for asynchronous check of time-out. More...

`#include <WatchdogThread.h>`

Collaboration diagram for WatchdogThread:
[legend]

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

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

## Private Member Functions
void | i_run ()
| Core function of the secondary thread.

## Private Attributes
boost::posix_time::time_duration | m_timeout
| Number of seconds allowed between pings.
boost::system_time | m_lastPing
| When the last ping was received.
std::auto_ptr< boost::thread > | m_thread
| Pointer to the running thread;.
bool | m_running
| Flag to mark the thread as running/stopped (avoid possible race conditions).
boost::mutex | m_lastPingMutex
| Mutex for the access to the m_lastPing data member.

## 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 25 of file WatchdogThread.h.

## Constructor & Destructor Documentation

WatchdogThread::WatchdogThread | ( | boost::posix_time::time_duration | timeout,
|  | bool | autostart = `false`
| ) |  |

Constructor.

Definition at line 12 of file WatchdogThread.cpp.

:
m_timeout(timeout), m_running(false)
{
// Start the thread immediately if requested.
if (autostart) start();
}

WatchdogThread::~WatchdogThread | ( |  | ) |
| virtual

Destructor.

Definition at line 19 of file WatchdogThread.cpp.

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

## Member Function Documentation

void WatchdogThread::action | ( |  | ) |
| protected virtual

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

Definition at line 79 of file WatchdogThread.cpp.

{
}

boost::system_time WatchdogThread::getLastPing | ( |  | ) | const
| inline

Get the time of latest ping.

Definition at line 61 of file WatchdogThread.h.

{
boost::mutex::scoped_lock lock(m_lastPingMutex);
return m_lastPing;
}

boost::posix_time::time_duration WatchdogThread::getTimeout | ( |  | ) | const
| inline

Get the current time-out value.

Definition at line 56 of file WatchdogThread.h.

{
return m_timeout;
}

void WatchdogThread::i_run | ( |  | ) |
| private

Core function of the secondary thread.

Definition at line 48 of file WatchdogThread.cpp.

{
// Copy of the last ping
boost::system_time lastPing = getLastPing();
// set initial check time
boost::system_time nextCheck = lastPing + getTimeout();
try {
// enter infinite loop
while (m_running) {
// Wait until the next check point time is reached.
// An early exit must be triggered by a call to this->interrupt(), which
// will produce an exception during the sleep.
boost::thread::sleep(nextCheck);
// 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 = boost::get_system_time() + getTimeout();
} else { // there was a ping
// schedule the next check for last_access + dt
nextCheck = lastPing = getLastPing();
nextCheck += getTimeout();
}
}
}
// Ignore the exception since it is used only to exit from the loop.
catch (boost::thread_interrupted&) {}
}

void WatchdogThread::onPing | ( |  | ) |
| protected virtual

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

Definition at line 83 of file WatchdogThread.cpp.

{
}

void WatchdogThread::onStart | ( |  | ) |
| protected virtual

User implemented function that will be called when starting.

Definition at line 87 of file WatchdogThread.cpp.

{
}

void WatchdogThread::onStop | ( |  | ) |
| protected virtual

User implemented function that will be called when stopping.

Definition at line 91 of file WatchdogThread.cpp.

{
}

void WatchdogThread::ping | ( |  | ) |
| inline

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

Definition at line 44 of file WatchdogThread.h.

{
boost::mutex::scoped_lock lock(m_lastPingMutex);
m_lastPing = boost::get_system_time();
onPing();
}

void WatchdogThread::setTimeout | ( | boost::posix_time::time_duration | timeout | ) |
| inline

Change the duration of the time-out.

Definition at line 51 of file WatchdogThread.h.

{
m_timeout = timeout;
}

void WatchdogThread::start | ( |  | ) |

Start the watchdog thread.

Definition at line 24 of file WatchdogThread.cpp.

{
if (!m_thread.get()) { // can be started only if the thread is not yet started
m_running = true;
// 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::auto_ptr<boost::thread>(new boost::thread(std::mem_fun(&WatchdogThread::i_run), this));
}
}

void WatchdogThread::stop | ( |  | ) |

Signal the watchdog thread to stop and wait for it.

Definition at line 36 of file WatchdogThread.cpp.

{
if (m_thread.get()) {
m_running = false; // mark the thread as stopped (interrupt doesn't work if the thread is not sleeping)
Gaudi::NanoSleep(1000000); // Wait a bit (1ms) to be sure that the interrupt happens during the sleep
m_thread->interrupt(); // tell the thread to stop (if it is waiting)
m_thread->join(); // wait for it
m_thread.reset(); // delete it
// call user-defined function
onStop();
}
}

## Member Data Documentation

boost::system_time WatchdogThread::m_lastPing
| private

When the last ping was received.

Definition at line 84 of file WatchdogThread.h.

boost::mutex WatchdogThread::m_lastPingMutex
| mutable private

Mutex for the access to the m_lastPing data member.

Definition at line 98 of file WatchdogThread.h.

bool WatchdogThread::m_running
| private

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

Definition at line 90 of file WatchdogThread.h.

std::auto_ptr<boost::thread> WatchdogThread::m_thread
| private

Pointer to the running thread;.

Definition at line 87 of file WatchdogThread.h.

boost::posix_time::time_duration WatchdogThread::m_timeout
| private

Number of seconds allowed between pings.

Definition at line 81 of file WatchdogThread.h.

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

- /afs/cern.ch/sw/Gaudi/releases/GAUDI/GAUDI_v25r0/GaudiKernel/GaudiKernel/WatchdogThread.h
- /afs/cern.ch/sw/Gaudi/releases/GAUDI/GAUDI_v25r0/GaudiKernel/src/Lib/WatchdogThread.cpp