ShiftingTransformProvider.java
- /* Copyright 2002-2022 CS GROUP
- * Licensed to CS GROUP (CS) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * CS licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package org.orekit.frames;
- import java.io.Serializable;
- import java.util.HashMap;
- import java.util.Map;
- import org.hipparchus.Field;
- import org.hipparchus.CalculusFieldElement;
- import org.hipparchus.util.FastMath;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.time.FieldAbsoluteDate;
- import org.orekit.utils.AngularDerivativesFilter;
- import org.orekit.utils.CartesianDerivativesFilter;
- import org.orekit.utils.GenericTimeStampedCache;
- /** Transform provider using thread-safe shifts on transforms sample.
- * <p>
- * The shifts take derivatives into account, up to user specified order.
- * </p>
- * @see GenericTimeStampedCache
- * @see InterpolatingTransformProvider
- * @since 7.1
- * @author Luc Maisonobe
- */
- public class ShiftingTransformProvider implements TransformProvider {
- /** Serializable UID. */
- private static final long serialVersionUID = 20150601L;
- /** First level cache. */
- private final InterpolatingTransformProvider interpolatingProvider;
- /** Cache for sample points. */
- private final transient GenericTimeStampedCache<Transform> cache;
- /** Field caches for sample points. */
- // we use Object as the value of fieldCaches because despite numerous attempts,
- // we could not find a way to use GenericTimeStampedCache<FieldTransform<? extends CalculusFieldElement<?>>
- // without the compiler complaining
- private final transient Map<Field<? extends CalculusFieldElement<?>>, Object> fieldCaches;
- /** Simple constructor.
- * @param rawProvider provider for raw (non-interpolated) transforms
- * @param cFilter filter for derivatives from the sample to use in interpolation
- * @param aFilter filter for derivatives from the sample to use in interpolation
- * @param gridPoints number of interpolation grid points
- * @param step grid points time step
- * @param maxSlots maximum number of independent cached time slots
- * in the {@link GenericTimeStampedCache time-stamped cache}
- * @param maxSpan maximum duration span in seconds of one slot
- * in the {@link GenericTimeStampedCache time-stamped cache}
- * @param newSlotInterval time interval above which a new slot is created
- * in the {@link GenericTimeStampedCache time-stamped cache}
- * @since 9.1
- */
- public ShiftingTransformProvider(final TransformProvider rawProvider,
- final CartesianDerivativesFilter cFilter,
- final AngularDerivativesFilter aFilter,
- final int gridPoints, final double step,
- final int maxSlots, final double maxSpan, final double newSlotInterval) {
- this(new InterpolatingTransformProvider(rawProvider, cFilter, aFilter,
- gridPoints, step, maxSlots, maxSpan, newSlotInterval),
- maxSlots, maxSpan, newSlotInterval);
- }
- /** Simple constructor.
- * @param interpolatingProvider first level cache provider
- * @param maxSlots maximum number of independent cached time slots
- * in the {@link GenericTimeStampedCache time-stamped cache}
- * @param maxSpan maximum duration span in seconds of one slot
- * in the {@link GenericTimeStampedCache time-stamped cache}
- * @param newSlotInterval time interval above which a new slot is created
- * in the {@link GenericTimeStampedCache time-stamped cache}
- */
- private ShiftingTransformProvider(final InterpolatingTransformProvider interpolatingProvider,
- final int maxSlots, final double maxSpan, final double newSlotInterval) {
- this.interpolatingProvider = interpolatingProvider;
- this.cache = new GenericTimeStampedCache<Transform>(2, maxSlots, maxSpan, newSlotInterval,
- new TransformGenerator(2,
- interpolatingProvider,
- interpolatingProvider.getStep()));
- this.fieldCaches = new HashMap<>();
- }
- /** Get the underlying provider for raw (non-interpolated) transforms.
- * @return provider for raw (non-interpolated) transforms
- */
- public TransformProvider getRawProvider() {
- return interpolatingProvider.getRawProvider();
- }
- /** Get the number of interpolation grid points.
- * @return number of interpolation grid points
- */
- public int getGridPoints() {
- return interpolatingProvider.getGridPoints();
- }
- /** Get the grid points time step.
- * @return grid points time step
- */
- public double getStep() {
- return interpolatingProvider.getStep();
- }
- /** {@inheritDoc} */
- public Transform getTransform(final AbsoluteDate date) {
- // retrieve a sample from the thread-safe cache
- final Transform closest = cache.getNeighbors(date).reduce((t0, t1) ->
- FastMath.abs(date.durationFrom(t0.getDate())) < FastMath.abs(date.durationFrom(t1.getDate())) ? t0 : t1
- ).get();
- return closest.shiftedBy(date.durationFrom(closest.getDate()));
- }
- /** {@inheritDoc} */
- public <T extends CalculusFieldElement<T>> FieldTransform<T> getTransform(final FieldAbsoluteDate<T> date) {
- @SuppressWarnings("unchecked")
- GenericTimeStampedCache<FieldTransform<T>> fieldCache =
- (GenericTimeStampedCache<FieldTransform<T>>) fieldCaches.get(date.getField());
- if (fieldCache == null) {
- fieldCache =
- new GenericTimeStampedCache<FieldTransform<T>>(cache.getNeighborsSize(),
- cache.getMaxSlots(),
- cache.getMaxSpan(),
- cache.getNewSlotQuantumGap(),
- new FieldTransformGenerator<>(date.getField(),
- cache.getNeighborsSize(),
- interpolatingProvider,
- interpolatingProvider.getStep()));
- fieldCaches.put(date.getField(), fieldCache);
- }
- // retrieve a sample from the thread-safe cache
- final FieldTransform<T> closest = fieldCache.getNeighbors(date.toAbsoluteDate()).reduce((t0, t1) ->
- date.durationFrom(t0.getDate()).abs().getReal() < date.durationFrom(t1.getDate()).abs().getReal() ?
- t0 : t1
- ).get();
- return closest.shiftedBy(date.durationFrom(closest.getDate()));
- }
- /** Replace the instance with a data transfer object for serialization.
- * <p>
- * This intermediate class serializes only the data needed for generation,
- * but does <em>not</em> serializes the cache itself (in fact the cache is
- * not serializable).
- * </p>
- * @return data transfer object that will be serialized
- */
- private Object writeReplace() {
- return new DTO(interpolatingProvider,
- cache.getMaxSlots(), cache.getMaxSpan(), cache.getNewSlotQuantumGap());
- }
- /** Internal class used only for serialization. */
- private static class DTO implements Serializable {
- /** Serializable UID. */
- private static final long serialVersionUID = 20150601L;
- /** Provider for raw (non-interpolated) transforms. */
- private final InterpolatingTransformProvider interpolatingProvider;
- /** Maximum number of independent cached time slots. */
- private final int maxSlots;
- /** Maximum duration span in seconds of one slot. */
- private final double maxSpan;
- /** Time interval above which a new slot is created. */
- private final double newSlotInterval;
- /** Simple constructor.
- * @param interpolatingProvider first level cache provider
- * @param maxSlots maximum number of independent cached time slots
- * in the {@link GenericTimeStampedCache time-stamped cache}
- * @param maxSpan maximum duration span in seconds of one slot
- * in the {@link GenericTimeStampedCache time-stamped cache}
- * @param newSlotInterval time interval above which a new slot is created
- * in the {@link GenericTimeStampedCache time-stamped cache}
- */
- private DTO(final InterpolatingTransformProvider interpolatingProvider,
- final int maxSlots, final double maxSpan, final double newSlotInterval) {
- this.interpolatingProvider = interpolatingProvider;
- this.maxSlots = maxSlots;
- this.maxSpan = maxSpan;
- this.newSlotInterval = newSlotInterval;
- }
- /** Replace the deserialized data transfer object with a {@link ShiftingTransformProvider}.
- * @return replacement {@link ShiftingTransformProvider}
- */
- private Object readResolve() {
- // build a new provider, with an empty cache
- return new ShiftingTransformProvider(interpolatingProvider,
- maxSlots, maxSpan, newSlotInterval);
- }
- }
- }