Package trclib.robotcore

Class TrcWatchdogMgr

java.lang.Object

trclib.robotcore.TrcWatchdogMgr

public class TrcWatchdogMgr
extends Object

This class is a singleton. It manages a list of watchdogs. Watchdogs are typically used for detecting thread deadlocks. A thread can register a watchdog with the Watchdog manager and periodically sends a heartbeat to it. If a heart beat is not sent within the heart beat threshold time, a stack trace for the thread will be dump to the trace log. This allows us to catch thread deadlocks quite easily. Since watchdog is designed per thread, only one watchdog needs to be registered for each thread.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	TrcWatchdogMgr.Watchdog	This class encapsulates the state of the watchdog.

Field Summary

Fields

Modifier and Type	Field	Description
private static final double	DEF_HEARTBEAT_THRESHOLD
private static final double	DEF_TASK_INTERVAL
private static TrcWatchdogMgr	instance
static final String	moduleName
static final TrcDbgTrace	staticTracer
private static final ArrayList<TrcWatchdogMgr.Watchdog>	watchdogList
private static final HashMap<Thread,TrcWatchdogMgr.Watchdog>	watchdogMap

Constructor Summary

Constructors

Modifier	Constructor	Description
private	TrcWatchdogMgr(double taskInterval)	Constructor: Creates an instance of the object.

Method Summary

Modifier and Type	Method	Description
static TrcWatchdogMgr	getInstance()	This method should only be called once.
static TrcWatchdogMgr	getInstance(double taskInterval)	This method should only be called once.
static TrcWatchdogMgr.Watchdog	getWatchdog()	This method returns the watchdog associated with the current thread.
static TrcWatchdogMgr.Watchdog	registerWatchdog(String name)	This method registers a new watchdog for the current thread if one is not already registered.
static TrcWatchdogMgr.Watchdog	registerWatchdog(String name, boolean paused)	This method registers a new watchdog for the current thread if one is not already registered.
static TrcWatchdogMgr.Watchdog	registerWatchdog(String name, double heartBeatThreshold, boolean paused)	This method registers a new watchdog for the current thread if one is not already registered.
static boolean	unregisterWatchdog(TrcWatchdogMgr.Watchdog watchdog)	This method removes the watchdog from the watchdog list and map.
private void	watchdogTask(TrcTaskMgr.TaskType taskType, TrcRobot.RunMode runMode, boolean slowPeriodicLoop)	This method runs periodically to check for watchdog timeouts.

Methods inherited from class java.lang.Object

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

Field Details

moduleName

public static final String moduleName

staticTracer

public static final TrcDbgTrace staticTracer

DEF_TASK_INTERVAL

private static final double DEF_TASK_INTERVAL

See Also:

• Constant Field Values

DEF_HEARTBEAT_THRESHOLD

private static final double DEF_HEARTBEAT_THRESHOLD

See Also:

• Constant Field Values

instance

private static TrcWatchdogMgr instance

watchdogList

private static final ArrayList<TrcWatchdogMgr.Watchdog> watchdogList

watchdogMap

private static final HashMap<Thread,TrcWatchdogMgr.Watchdog> watchdogMap

Constructor Details

TrcWatchdogMgr

private TrcWatchdogMgr(double taskInterval)

Constructor: Creates an instance of the object.

Parameters:

taskInterval - specifies the watchdog task interval.

Method Details

getInstance

public static TrcWatchdogMgr getInstance(double taskInterval)

This method should only be called once. It creates a singleton of the Watchdog Manager. If it is called again, it will just return the Watchdog Manager instance created previously.

Parameters:

taskInterval - specifies the watchdog task interval.

Returns:

Watchdog Manager instance.

getInstance

public static TrcWatchdogMgr getInstance()

This method should only be called once. It creates a singleton of the Watchdog Manager. If it is called again, it will just return the Watchdog Manager instance created previously.

Returns:

Watchdog Manager instance.

registerWatchdog

public static TrcWatchdogMgr.Watchdog registerWatchdog(String name,
 double heartBeatThreshold,
 boolean paused)

This method registers a new watchdog for the current thread if one is not already registered. Important: this method must be called in the thread the watchdog is monitoring.

Parameters:

name - specifies the name of the watchdog.

heartBeatThreshold - specifies the maximum heart beat interval in seconds.

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

Returns:

newly created watchdog.

registerWatchdog

public static TrcWatchdogMgr.Watchdog registerWatchdog(String name,
 boolean paused)

This method registers a new watchdog for the current thread if one is not already registered. Important: this method must be called in the thread the watchdog is monitoring.

Parameters:

name - specifies the name of the watchdog.

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

Returns:

newly created watchdog.

registerWatchdog

public static TrcWatchdogMgr.Watchdog registerWatchdog(String name)

This method registers a new watchdog for the current thread if one is not already registered. Important: this method must be called in the thread the watchdog is monitoring.

Parameters:

name - specifies the name of the watchdog.

Returns:

newly created watchdog.

unregisterWatchdog

public static boolean unregisterWatchdog(TrcWatchdogMgr.Watchdog watchdog)

This method removes the watchdog from the watchdog list and map. It can be called from any thread as long as it provides the watchdog to be unregistered.

Parameters:

watchdog - specifies the watchdog to be removed.

Returns:

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

getWatchdog

public static TrcWatchdogMgr.Watchdog getWatchdog()

This method returns the watchdog associated with the current thread.

Returns:

watchdog associated with the current thread.

watchdogTask

private void watchdogTask(TrcTaskMgr.TaskType taskType,
 TrcRobot.RunMode runMode,
 boolean slowPeriodicLoop)

This method runs periodically to check for watchdog timeouts.

Parameters:

taskType - specifies the type of task being run.

runMode - specifies the current robot run mode.

slowPeriodicLoop - specifies true if it is running the slow periodic loop on the main robot thread, false otherwise.