ShiftingTransformProvider.java
- /* Copyright 2002-2016 CS Systèmes d'Information
- * Licensed to CS Systèmes d'Information (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.ArrayList;
- import java.util.List;
- import org.apache.commons.math3.util.FastMath;
- import org.orekit.errors.OrekitException;
- import org.orekit.errors.OrekitExceptionWrapper;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.utils.AngularDerivativesFilter;
- import org.orekit.utils.CartesianDerivativesFilter;
- import org.orekit.utils.GenericTimeStampedCache;
- import org.orekit.utils.TimeStampedGenerator;
- /** 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;
- /** 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 earliest earliest supported date
- * @param latest latest supported date
- * @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}
- */
- public ShiftingTransformProvider(final TransformProvider rawProvider,
- final CartesianDerivativesFilter cFilter,
- final AngularDerivativesFilter aFilter,
- final AbsoluteDate earliest, final AbsoluteDate latest,
- final int gridPoints, final double step,
- final int maxSlots, final double maxSpan, final double newSlotInterval) {
- this(new InterpolatingTransformProvider(rawProvider, cFilter, aFilter,
- earliest, latest, 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 Generator(), Transform.class);
- }
- /** 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) throws OrekitException {
- try {
- // retrieve a sample from the thread-safe cache
- final List<Transform> sample = cache.getNeighbors(date);
- final double dt0 = date.durationFrom(sample.get(0).getDate());
- final double dt1 = date.durationFrom(sample.get(1).getDate());
- if (FastMath.abs(dt0) < FastMath.abs(dt1)) {
- return sample.get(0).shiftedBy(dt0);
- } else {
- return sample.get(1).shiftedBy(dt1);
- }
- } catch (OrekitExceptionWrapper oew) {
- // something went wrong while generating the sample,
- // we just forward the exception up
- throw oew.getException();
- }
- }
- /** 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);
- }
- }
- /** Local generator for thread-safe cache. */
- private class Generator implements TimeStampedGenerator<Transform> {
- /** {@inheritDoc} */
- public List<Transform> generate(final Transform existing, final AbsoluteDate date) {
- try {
- final List<Transform> generated = new ArrayList<Transform>();
- if (existing == null) {
- // no prior existing transforms, just generate a first set
- for (int i = 0; i < cache.getNeighborsSize(); ++i) {
- generated.add(interpolatingProvider.getTransform(date.shiftedBy(i * interpolatingProvider.getStep())));
- }
- } else {
- // some transforms have already been generated
- // add the missing ones up to specified date
- AbsoluteDate t = existing.getDate();
- if (date.compareTo(t) > 0) {
- // forward generation
- do {
- t = t.shiftedBy(interpolatingProvider.getStep());
- generated.add(generated.size(), interpolatingProvider.getTransform(t));
- } while (t.compareTo(date) <= 0);
- } else {
- // backward generation
- do {
- t = t.shiftedBy(-interpolatingProvider.getStep());
- generated.add(0, interpolatingProvider.getTransform(t));
- } while (t.compareTo(date) >= 0);
- }
- }
- // return the generated transforms
- return generated;
- } catch (OrekitException oe) {
- throw new OrekitExceptionWrapper(oe);
- }
- }
- }
- }