Package trclib.robotcore

Class TrcWatchdogMgr.Watchdog

java.lang.Object

trclib.robotcore.TrcWatchdogMgr.Watchdog

Enclosing class:

TrcWatchdogMgr

public static class TrcWatchdogMgr.Watchdog
extends Object

This class encapsulates the state of the watchdog. A watchdog has an identifiable name, an associated thread, a maximum time interval between which the heart beat must be received and the next heart beat expiraton time.

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	expired
private double	heartBeatExpiredTime
private final double	heartBeatThreshold
private final String	name
private boolean	paused
private final Thread	thread

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Watchdog(String name, Thread thread, double heartBeatThreshold, boolean paused)	Constructor: Creates an instance of the object.

Method Summary

Modifier and Type	Method	Description
private boolean	checkForExpiration()	This method checks if the watchdog has expired.
double	getHeartBeatThreshold()	This method returns the heart beat threshold time for the watchdog.
void	pauseWatch()	This method is called to pause watchdog monitoring.
void	resumeWatch()	This method is called to resume watchdog monitoring.
void	sendHeartBeat()	This method is called by the thread that registered the watchdog to send a heart beat.
String	toString()	This method returns the string containing the info of the watchdog.
boolean	unregister()	This method unregisters this watchdog from Watchdog Manager.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

name

private final String name

heartBeatThreshold

private final double heartBeatThreshold

thread

private final Thread thread

heartBeatExpiredTime

private volatile double heartBeatExpiredTime

expired

private volatile boolean expired

paused

private volatile boolean paused

Constructor Details

Watchdog

private Watchdog(String name,
 Thread thread,
 double heartBeatThreshold,
 boolean paused)

Constructor: Creates an instance of the object.

Parameters:

name - specifies the name of the watchdog.

thread - specifies the thread the watchdog is monitoring.

heartBeatThreshold - specifies the maximum heart beat interval in seconds.

paused - specifies true to create the watchdog in paused mode, false otherwise.

Method Details

pauseWatch

public void pauseWatch()

This method is called to pause watchdog monitoring. It is useful for a thread to call this before going into sleep or a wait knowing it won't be able to send periodic heartbeat to prevent a watchdog timeout.

resumeWatch

public void resumeWatch()

This method is called to resume watchdog monitoring. It is useful for a thread to call this right after waking up from a sleep or a wait so watchdog monitoring will be resumed.

sendHeartBeat

public void sendHeartBeat()

This method is called by the thread that registered the watchdog to send a heart beat. This will update the next heart beat expiration time.

checkForExpiration

private boolean checkForExpiration()

This method checks if the watchdog has expired.

Returns:

true if no heartbeat has been received for the specified threshold period, false otherwise.

unregister

public boolean unregister()

This method unregisters this watchdog from Watchdog Manager. Important: this method must be called in the thread the watchdog is monitoring. In other words, the caller's thread must be the owner of the watchdog.

Returns:

true if watchdog is unregistered successfully, false if watchdog does not exist.

toString

public String toString()

This method returns the string containing the info of the watchdog.

Overrides:

toString in class Object

Returns:

string form of the watchdog info.

getHeartBeatThreshold

public double getHeartBeatThreshold()

This method returns the heart beat threshold time for the watchdog.

Returns:

watchdog heart beat threshold time in seconds.