agi.foundation.segmentpropagation

(agi.foundation.models-2024r2.jar)

Class SegmentPropagator

java.lang.Object

agi.foundation.segmentpropagation.SegmentPropagator

All Implemented Interfaces:

IDisposable, ICloneWithContext, IThreadAware, AutoCloseable

Direct Known Subclasses:

SegmentListPropagator

public abstract class SegmentPropagator
extends Object
implements IThreadAware, IDisposable

The abstract type for a segment's propagator. This will perform the propagation and produce SegmentResults.

There are two types of propagation that need to be supported. There is the normal SegmentPropagator.propagateSegment(SegmentListResults,SegmentConfiguration,ITrackCalculationProgress) call that will start from where the previous segment stopped. There is also the SegmentPropagator.propagateTo(agi.foundation.segmentpropagation.SegmentResults, agi.foundation.time.JulianDate) method that is needed for when a segment propagated after this one needs to back up for some reason. Propagation forwards and backwards must be handled as well.

See the Segments topic for more details about using segments.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SegmentPropagator(SegmentDefinition previousSegment, SegmentDefinition creator, EvaluatorGroup group) Initializes a new instance.
protected	SegmentPropagator(SegmentPropagator existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.

Method Summary

Modifier and Type	Method and Description
void	addPropagationFinishedEvent(EventHandler<SegmentPropagationEventArgs> value) An event that gets raised when propagation finishes.
void	applyResults(SegmentResults results) This method sets propagator's state via the input results.
abstract Object	clone(CopyContext context) Clones this object using the specified context.
protected void	defaultStateAdaptation(ITimeBasedState initialState, ITimeBasedState finalState) Performs the default adaptation of the elements in the initialState into the finalState.
void	dispose() Releases any resources associated with this instance.
protected void	dispose(boolean disposing) Releases any resources associated with this instance.
List<StateElementAdapter>	getAdapters() Gets a list of the StateElementAdapters that this segment can use in its propagation.
SegmentDefinition	getIdentifier() Gets the definition that created this propagator.
boolean	getIsThreadSafe() Gets a value indicating whether the methods on this instance are safe to call from multiple threads simultaneously.
String	getName() Gets the name of this SegmentPropagator.
SegmentConfiguration	getOriginalConfiguration() Gets the original configuration for this segment.
IntegrationSense	getPropagationDirection() Gets the initial direction of propagation.
StateForNextSegmentBehavior	getStateForNextSegmentBehavior() Gets which state should be passed to the next SegmentPropagator.
SegmentResults	propagate() Propagates the segment assuming no initial state is passed in.
SegmentResults	propagate(ITimeBasedState initialState) Propagates the segment starting from the initialState.
SegmentResults	propagate(ITimeBasedState initialState, ITrackCalculationProgress progressTracker) Propagates the segment starting from the initialState.
SegmentResults	propagate(ITimeBasedState initialState, SegmentListResults cumulativeResults) Propagates the segment starting from the initialState.
SegmentResults	propagate(SegmentConfiguration editedConfiguration, ITrackCalculationProgress progressTracker) Propagates the segment.
SegmentResults	propagate(SegmentListResults cumulativeResults) Propagates the segment.
SegmentResults	propagate(SegmentListResults cumulativeResults, SegmentConfiguration editedConfiguration, ITrackCalculationProgress progressTracker) Propagates the segment with the given parameters.
protected abstract SegmentResults	propagateSegment(SegmentListResults cumulativeResults, SegmentConfiguration editedConfiguration, ITrackCalculationProgress progressTracker) The method that actually propagates the segment.
abstract ITimeBasedState	propagateTo(SegmentResults results, JulianDate dateToPropagateTo) Propagates a segment to the time or independent variable specified in the dateToPropagateTo.
void	removePropagationFinishedEvent(EventHandler<SegmentPropagationEventArgs> value) An event that gets raised when propagation finishes.
protected void	setOriginalConfiguration(SegmentConfiguration value) Sets the original configuration for this segment.
String	toString() Returns a string representation of the object.
static boolean	updateProgressTrackerAndReturnIfCanceled(ITrackCalculationProgress progressTracker) A helper method to handle the progress tracker that the various SegmentPropagator.propagate() methods have.

Methods inherited from class java.lang.Object

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

Methods inherited from interface agi.foundation.compatibility.IDisposable

close

Constructor Detail

SegmentPropagator

protected SegmentPropagator(@Nullable
                            SegmentDefinition previousSegment,
                            @Nonnull
                            SegmentDefinition creator,
                            @Nonnull
                            EvaluatorGroup group)

Initializes a new instance.

Parameters:

previousSegment - The previous segment. If a SegmentListPropagator is creating its children propagators, it should pass in its previous segment to its first child segment. A valid SegmentPropagator should be returned even if this parameter is null.

creator - The SegmentDefinition creating this propagator.

group - The EvaluatorGroup to use when creating evaluators.

SegmentPropagator

protected SegmentPropagator(@Nonnull
                            SegmentPropagator existingInstance,
                            @Nonnull
                            CopyContext context)

Initializes a new instance as a copy of an existing instance.

See ICloneWithContext.clone(CopyContext) for more information about how to implement this constructor in a derived class.

Parameters:

existingInstance - The existing instance to copy.

context - A CopyContext that controls the depth of the copy.

Throws:

ArgumentNullException - Thrown when existingInstance or context is null.

Method Detail

clone

public abstract Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

dispose

public final void dispose()

Releases any resources associated with this instance.

Specified by:

dispose in interface IDisposable

dispose

protected void dispose(boolean disposing)

Releases any resources associated with this instance.

Parameters:

disposing - true to release both managed and unmanaged resources; false to release only unmanaged resources.

getIsThreadSafe

public boolean getIsThreadSafe()

Gets a value indicating whether the methods on this instance are safe to call from multiple threads simultaneously.

If this property is true, all methods and properties are guaranteed to be thread safe. Conceptually, an object that returns true for this method acts as if there is a lock protecting each method and property such that only one thread at a time can be inside any method or property in the class. In reality, such locks are generally not used and are in fact discouraged. However, the user must not experience any exceptions or inconsistent behavior that would not be experienced if such locks were used.

If this property is false, the behavior when using this class from multiple threads simultaneously is undefined and may include inconsistent results and exceptions. Clients wishing to use multiple threads should call CopyForAnotherThread.copy(T) to get a separate instance of the object for each thread.

Specified by:

getIsThreadSafe in interface IThreadAware

updateProgressTrackerAndReturnIfCanceled

public static boolean updateProgressTrackerAndReturnIfCanceled(@Nullable
                                                               ITrackCalculationProgress progressTracker)

A helper method to handle the progress tracker that the various SegmentPropagator.propagate() methods have. Because how long propagation will take cannot be known ahead of time, the progress is reported as -1. You can however use the progress tracker to cancel propagation.

Parameters:

progressTracker - The progress tracker that can be used to cancel propagation.

Returns:

true if propagation should stop; otherwise false.

addPropagationFinishedEvent

public final void addPropagationFinishedEvent(EventHandler<SegmentPropagationEventArgs> value)

An event that gets raised when propagation finishes. This event gets raised in this base type; it should not be run in the SegmentPropagator.propagateSegment(SegmentListResults,SegmentConfiguration,ITrackCalculationProgress) method.

removePropagationFinishedEvent

public final void removePropagationFinishedEvent(EventHandler<SegmentPropagationEventArgs> value)

An event that gets raised when propagation finishes. This event gets raised in this base type; it should not be run in the SegmentPropagator.propagateSegment(SegmentListResults,SegmentConfiguration,ITrackCalculationProgress) method.

getIdentifier

@Nonnull
public final SegmentDefinition getIdentifier()

Gets the definition that created this propagator. This is to only be used as an identifier.

getPropagationDirection

@Nonnull
public final IntegrationSense getPropagationDirection()

Gets the initial direction of propagation.

toString

public String toString()

Description copied from class: java.lang.Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.

getAdapters

@Nonnull
public final List<StateElementAdapter> getAdapters()

Gets a list of the StateElementAdapters that this segment can use in its propagation.

getName

public final String getName()

Gets the name of this SegmentPropagator.

getStateForNextSegmentBehavior

@Nonnull
public final StateForNextSegmentBehavior getStateForNextSegmentBehavior()

Gets which state should be passed to the next SegmentPropagator.

defaultStateAdaptation

protected final void defaultStateAdaptation(ITimeBasedState initialState,
                                            ITimeBasedState finalState)

Performs the default adaptation of the elements in the initialState into the finalState. Note that elements that do not exist in both states will not be adapted.

Parameters:

initialState - The initial state whose Motions will be transformed in some way by the Adapters (get) and set in the finalState.

finalState - The state that will be set with the adapted values from the initialState.

applyResults

public void applyResults(@Nonnull
                         SegmentResults results)

This method sets propagator's state via the input results. For SegmentPropagators that have state, there may be times when that state should be manually set (sometimes for performance considerations, when the propagator will be called multiple times and it should start from where it left off).

Parameters:

results - The results to apply.

getOriginalConfiguration

@Nonnull
public final SegmentConfiguration getOriginalConfiguration()

Gets the original configuration for this segment. This must be set when the propagator is constructed. This should be ignored during propagation if a configuration is passed into the SegmentPropagator.propagateSegment(SegmentListResults,SegmentConfiguration,ITrackCalculationProgress) method.

setOriginalConfiguration

protected final void setOriginalConfiguration(@Nonnull
                                              SegmentConfiguration value)

Sets the original configuration for this segment. This must be set when the propagator is constructed. This should be ignored during propagation if a configuration is passed into the SegmentPropagator.propagateSegment(SegmentListResults,SegmentConfiguration,ITrackCalculationProgress) method.

propagate

@Nonnull
public SegmentResults propagate(@Nullable
                                          SegmentListResults cumulativeResults,
                                          @Nullable
                                          SegmentConfiguration editedConfiguration,
                                          @Nullable
                                          ITrackCalculationProgress progressTracker)

Propagates the segment with the given parameters.

Parameters:

cumulativeResults - The results of propagation up to this point.

editedConfiguration - The segment configuration that some other segment has determined that this segment should run. If it is null then use this segments OriginalConfiguration (get / set).

progressTracker - An optional progress tracker. How long the segment will take to propagate generally is not known ahead of time, so the reported progress completed is set to -1. However you can cancel propagation with the tracker.

Returns:

This segments propagation results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagate

@Nonnull
public SegmentResults propagate()

Propagates the segment assuming no initial state is passed in. Some segments do not require an initial state to be passed in. However other segments do; such types should override this method and provide a detailed error message in a proper RuntimeException in such a case.

Depending on the segment type being propagated the SegmentResults returned can be safely cast to a more specific type. See the class documentation for the derived type for more information.

Returns:

This segments propagation results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagate

@Nonnull
public final SegmentResults propagate(@Nullable
                                                SegmentListResults cumulativeResults)

Propagates the segment.

Parameters:

cumulativeResults - The results of all propagation up to this point. This may be null if this segment is not being propagated in a SegmentListPropagator.

Returns:

This segments propagation results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagate

@Nonnull
public final SegmentResults propagate(ITimeBasedState initialState)

Propagates the segment starting from the initialState.

Parameters:

initialState - The initial state for this segment to propagate from. This is akin to the final state of the previous segment; it will be processed by the Adapters (get) before being propagated.

Returns:

This segments propagation results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagate

@Nonnull
public final SegmentResults propagate(ITimeBasedState initialState,
                                                @Nullable
                                                SegmentListResults cumulativeResults)

Propagates the segment starting from the initialState.

Parameters:

initialState - The initial state for this segment to propagate from. This is usually the final state of the previous segment. It will be processed by any the Adapters (get) before being propagated.

cumulativeResults - The results of the SegmentListPropagator that contains this segment. This may be null if this segment is being propagated independent of a SegmentListPropagator. In the simple case, this is only needed to provide the StateForNextSegment (get) that this SegmentPropagator should start propagating from. However, if the concrete SegmentPropagator will propagate multiple segments, then the StateForNextSegment (get) must be set after each individual SegmentPropagator is propagated. You may also need to maintain the SegmentResults (get) collection to avoid having the same SegmentResults included twice (the SegmentResults for each SegmentPropagator gets added automatically to the cumulativeResults when it is propagated). Also, if there is even the possibility of the SegmentPropagator needing to back up into a previous segment, the SegmentListResults.regenerateEphemerisForOverallTrajectory() method after each child SegmentPropagator is propagated.

Returns:

This segments propagation results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagate

@Nonnull
public final SegmentResults propagate(ITimeBasedState initialState,
                                                @Nullable
                                                ITrackCalculationProgress progressTracker)

Propagates the segment starting from the initialState.

Parameters:

initialState - The initial state for this segment to propagate from. This is usually the final state of the previous segment. It will be processed by any the Adapters (get) before being propagated.

progressTracker - An optional progress tracker. How long the segment will take to propagate generally is not known ahead of time, so the reported progress completed is set to -1. However you can cancel propagation with the tracker.

Returns:

This segments propagation results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagate

@Nonnull
public final SegmentResults propagate(@Nonnull
                                                SegmentConfiguration editedConfiguration,
                                                @Nullable
                                                ITrackCalculationProgress progressTracker)

Propagates the segment.

Parameters:

editedConfiguration - The segment configuration that some other segment has determined that this segment should run. If it is null then use the segments original configuration.

progressTracker - An optional progress tracker. How long the segment will take to propagate generally is not known ahead of time, so the reported progress completed is set to -1. However you can cancel propagation with the tracker.

Returns:

This segments propagation results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagateSegment

@Nonnull
protected abstract SegmentResults propagateSegment(@Nullable
                                                             SegmentListResults cumulativeResults,
                                                             @Nullable
                                                             SegmentConfiguration editedConfiguration,
                                                             @Nullable
                                                             ITrackCalculationProgress progressTracker)

The method that actually propagates the segment. This should never be called directly; instead call whatever SegmentPropagator.propagate() method most appropriate to your problem.

Parameters:

cumulativeResults - The results of the SegmentListPropagator that contains this segment. This may be null if this segment is being propagated independent of a SegmentListPropagator. In the simple case, this is only needed to provide the StateForNextSegment (get) that this SegmentPropagator should start propagating from. However, if the concrete SegmentPropagator will propagate multiple segments, then the StateForNextSegment (get) must be set after each individual SegmentPropagator is propagated. You may also need to maintain the SegmentResults (get) collection to avoid having the same SegmentResults included twice (the SegmentResults for each SegmentPropagator gets added automatically to the cumulativeResults when it is propagated). Also, if there is even the possibility of the SegmentPropagator needing to back up into a previous segment, the SegmentListResults.regenerateEphemerisForOverallTrajectory() method after each child SegmentPropagator is propagated.

editedConfiguration - The segment configuration that some other segment has determined that this segment should run. If it is null then use the segments OriginalConfiguration (get / set).

progressTracker - An optional progress tracker. How long the segment will take to propagate generally is not known ahead of time, so the reported progress completed is set to -1. However you can cancel propagation with the tracker.

Returns:

This segments propagation results. This method must fill in all of the relevant properties in the returned results. See the documentation of the derived type to determine if these SegmentResults may be cast to a more specific type.

propagateTo

@Nullable
public abstract ITimeBasedState propagateTo(@Nonnull
                                                       SegmentResults results,
                                                       @Nonnull
                                                       JulianDate dateToPropagateTo)

Propagates a segment to the time or independent variable specified in the dateToPropagateTo. This method is needed to assist the case when segments might overlap. If a later segment realizes that it needs to find a different final state from this SegmentPropagator, this method should be used to find that new final state.

Consider calling SegmentListResults.propagateToAssumingTimeBasedStates(agi.foundation.time.JulianDate, agi.foundation.segmentpropagation.SegmentResults, agi.foundation.segmentpropagation.SegmentListResults) instead of this method directly.

For segments that happen instantaneously then this should just return the state computed (although generally this method should never need to be called on such segments since there is no "when" to propagate to, you can pull the state from the results directly). For a segment that produces an ephemeris, this should find the state right before the offset's independent variable and take one step to that independent variable. If the segment returns two states at the same time, PropagationDirection (get) should be checked, and if propagation is IntegrationSense.INCREASING the final state should be returned, or the initial state if propagation is backwards.

Parameters:

results - The results previously computed by this SegmentPropagator. When used with a SegmentListPropagator, the results of the actual nested SegmentPropagator should be passed in.

dateToPropagateTo - The date of the returned state.

Returns:

The state at dateToPropagateTo.