javax.safetycritical

Class MissionSequencer<SpecificMission extends Mission>

java.lang.Object

javax.safetycritical.ManagedEventHandler

javax.safetycritical.MissionSequencer<SpecificMission>

All Implemented Interfaces:

ManagedSchedulable

@SCJAllowed
public abstract class MissionSequencer<SpecificMission extends Mission>
extends ManagedEventHandler

A MissionSequencer oversees a sequence of Mission executions. The sequence may include interleaved execution of independent missions and repeated executions of missions.

As a subclass of ManagedEventHandler, MissionSequencer has an execution priority and memory budget as specified by constructor parameters.

The MissionSequencer executes vendor-supplied infrastructure code which invokes user-defined implementations of the method getNextMission, and for each mission the user-defined initialize and cleanUp methods.

During execution of an inner-nested mission, the MissionSequencer remains blocked waiting for the mission to terminate. An invocation of requestSequenceTermination will unblock it so that it can perform an invocation of the running mission's requestTermination method, if the mission is still running and its termination has not already been requested.

Note that if a MissionSequencer object is preallocated by the application, it must be allocated in the same scope as its corresponding Missions.

Version:

1.2; - December 2013

Author:

Anders P. Ravn, Aalborg University, apr@cs.aau.dk,
Hans Søndergaard, VIA University College, Denmark, hso@via.dk

Relative_to_SCJ_Draft_Version_0.94:

- SCJ issue: Why Level 2 only for the following two methods?

• public final void requestSequenceTermination()
  
• public final boolean sequenceTerminationPending()

Constructor Summary

Constructors

Constructor and Description
MissionSequencer(PriorityParameters priority, StorageParameters storage) Constructs a MissionSequencer to run at the priority and with the memory resources specified by its parameters.

Method Summary

Methods

Modifier and Type	Method and Description
void	cleanUp() Runs end-of-mission clean up associated with this schedulable object.
void	handleAsyncEvent() This method is declared final because the implementation is provided by the infrastructure of the SCJ implementation and shall not be overridden.
void	register() Registers this event handler with the current mission.
void	requestSequenceTermination() Invokes the currently running Mission's requestTermination method.
boolean	sequenceTerminationPending() Checks if the current Mission is trying to terminate.

Methods inherited from class javax.safetycritical.ManagedEventHandler

getLastReleaseTime

Methods inherited from class java.lang.Object

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

Constructor Detail

MissionSequencer

@SCJAllowed
@SCJRestricted(value=INITIALIZE)
public MissionSequencer(PriorityParameters priority,
                                                        StorageParameters storage)

Constructs a MissionSequencer to run at the priority and with the memory resources specified by its parameters.

Method Detail

handleAsyncEvent

@SCJAllowed(value=INFRASTRUCTURE)
public final void handleAsyncEvent()

This method is declared final because the implementation is provided by the infrastructure of the SCJ implementation and shall not be overridden.
This method performs all of the activities that correspond to sequencing of Missions by this MissionSequencer.

Specified by:

handleAsyncEvent in class ManagedEventHandler

register

public final void register()

Description copied from class: ManagedEventHandler

Registers this event handler with the current mission.

Specified by:

register in interface ManagedSchedulable

Overrides:

register in class ManagedEventHandler

requestSequenceTermination

@SCJAllowed
public final void requestSequenceTermination()

Invokes the currently running Mission's requestTermination method.
Upon completion of the currently running Mission, this MissionSequencer returns without starting any additional missions.

Note that requestSequenceTermination does not force the sequence to terminate because the currently running Mission must voluntarily relinquish its resources.

sequenceTerminationPending

@SCJAllowed
public final boolean sequenceTerminationPending()

Checks if the current Mission is trying to terminate.

Returns:

True if and only if this MissionSequencer's requestSequenceTermination method has been invoked.

cleanUp

public final void cleanUp()

Description copied from interface: ManagedSchedulable

Runs end-of-mission clean up associated with this schedulable object.

Specified by:

cleanUp in interface ManagedSchedulable

Overrides:

cleanUp in class ManagedEventHandler