javax.realtime
Class ImportanceParameters

java.lang.Object
  javax.realtime.SchedulingParameters
      javax.realtime.PriorityParameters
          javax.realtime.ImportanceParameters

public class ImportanceParameters

extends PriorityParameters

Importance is an additional scheduling metric that may be used by some priority-based scheduling algorithms during overload conditions to differentiate execution order among threads of the same priority. In some real-time systems an external physical process determines the period of many threads. If rate-monotonic priority assignment is used to assign priorities many of the threads in the system may have the same priority because their periods are the same. However, it is conceivable that some threads may be more important than others and in an overload situation importance can help the scheduler decide which threads to execute first. The base scheduling algorithm represented by PriorityScheduler is not required to use importance. However, the RTSJ strongly suggests to implementers that a fairly simple subclass of PriorityScheduler that uses importance can offer value to some real-time applications.

Author:

Angelo Corsaro

Field Summary

protected int

importance

Fields inherited from class javax.realtime.PriorityParameters

priority

Constructor Summary

ImportanceParameters(int priority, int importance)
Create aninstance of ImportanceParameters.

Method Summary

int	getImportance() Gets the importance value.
void	setImportance(int importance) Sets the importance value.
String	toString()

Methods inherited from class javax.realtime.PriorityParameters

getPriority, setPriority

Methods inherited from class java.lang.Object

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

Field Detail

importance

protected int importance

Constructor Detail

ImportanceParameters

public ImportanceParameters(int priority,
                            int importance)
                     throws IllegalArgumentException

Create aninstance of ImportanceParameters.

Parameters:

priority - The priority assigned to a thread. This value is used in place of the value returned by java.lang.Thread.setPriority(int)

importance - The importance value assigned to a thread.

Throws:

IllegalArgumentException - Thrown if the given priority value is less than the minimum priority of the scheduler of any of the associated threads or greater then the maximum priority of the scheduler of any of the associated threads.

Method Detail

getImportance

public int getImportance()

Gets the importance value.

Returns:

the importance value.

setImportance

public void setImportance(int importance)

Sets the importance value.

Parameters:

importance - the new importance value.

toString

public String toString()

Overrides:

toString in class PriorityParameters