EventsLogger.java
/* Copyright 2002-2025 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.propagation.events;
import java.util.ArrayList;
import java.util.List;
import org.hipparchus.ode.events.Action;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.events.handlers.EventHandler;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.TimeStamped;
/** This class logs events detectors events during propagation.
*
* <p>As {@link EventDetector events detectors} are triggered during
* orbit propagation, an event specific {@link
* EventHandler#eventOccurred(SpacecraftState, EventDetector, boolean) eventOccurred}
* method is called. This class can be used to add a global logging
* feature registering all events with their corresponding states in
* a chronological sequence (or reverse-chronological if propagation
* occurs backward).
* <p>This class works by wrapping user-provided {@link EventDetector
* events detectors} before they are registered to the propagator. The
* wrapper monitor the calls to {@link
* EventHandler#eventOccurred(SpacecraftState, EventDetector, boolean) eventOccurred}
* and store the corresponding events as {@link LoggedEvent} instances.
* After propagation is complete, the user can retrieve all the events
* that have occurred at once by calling method {@link #getLoggedEvents()}.</p>
*
* @author Luc Maisonobe
*/
public class EventsLogger {
/** List of occurred events. */
private final List<LoggedEvent> log;
/** Flag to save reset states. */
private final boolean logResetStates;
/** Constructor from existing log with flag to keep reset states.
* @param logResetStates flag to turn on the storage of reset states (if false, getter in event is set to null)
* @param inputLog log to be kept at start
* <p>
* Build an non-empty logger for events detectors.
* </p>
* @since 14.0
*/
public EventsLogger(final boolean logResetStates, final List<LoggedEvent> inputLog) {
this.logResetStates = logResetStates;
this.log = new ArrayList<>(inputLog);
}
/** Constructor from existing log.
* @param inputLog log to be kept at start
* <p>
* Build an non-empty logger for events detectors.
* </p>
* @since 14.0
*/
public EventsLogger(final List<LoggedEvent> inputLog) {
this(inputLog.stream().anyMatch(loggedEvent -> loggedEvent.getResetState() != null), inputLog);
}
/** Simple constructor.
* <p>
* Build an empty logger for events detectors.
* </p>
*/
public EventsLogger() {
this(true, new ArrayList<>());
}
/** Monitor an event detector.
* <p>
* In order to monitor an event detector, it must be wrapped thanks to
* this method as follows:
* </p>
* <pre>
* Propagator propagator = new XyzPropagator(...);
* EventsLogger logger = new EventsLogger();
* EventDetector detector = new UvwDetector(...);
* propagator.addEventDetector(logger.monitorDetector(detector));
* </pre>
* <p>
* Note that the event detector returned by the {@link
* LoggedEvent#getEventDetector() getEventDetector} method in
* {@link LoggedEvent LoggedEvent} instances returned by {@link
* #getLoggedEvents()} are the {@code monitoredDetector} instances
* themselves, not the wrapping detector returned by this method.
* </p>
* @param monitoredDetector event detector to monitor
* @return the wrapping detector to add to the propagator
* @param <T> class type for the generic version
*/
public <T extends EventDetector> EventDetector monitorDetector(final T monitoredDetector) {
return new LoggingWrapper(monitoredDetector);
}
/** Clear the logged events.
*/
public void clearLoggedEvents() {
log.clear();
}
/** Get an immutable copy of the logged events.
* <p>
* The copy is independent of the logger. It is preserved
* event if the {@link #clearLoggedEvents() clearLoggedEvents} method
* is called and the logger reused in another propagation.
* </p>
* @return an immutable copy of the logged events
*/
public List<LoggedEvent> getLoggedEvents() {
return new ArrayList<>(log);
}
/** Class for logged events entries. */
public static class LoggedEvent implements TimeStamped {
/** Event detector triggered. */
private final EventDetector detector;
/** Triggering state. */
private final SpacecraftState state;
/** Increasing/decreasing status. */
private final boolean increasing;
/** State after reset if any, otherwise same than triggering state. */
private final SpacecraftState resetState;
/** Action registered by event handler. */
private final Action action;
/** Constructor.
* @param detector detector for event that was triggered
* @param state state at event trigger date
* @param resetState state after reset if any, otherwise same as event state
* @param increasing indicator if the event switching function was increasing
* or decreasing at event occurrence date
* @param action action from handler
* @since 14.0
*/
private LoggedEvent(final EventDetector detector, final SpacecraftState state,
final SpacecraftState resetState, final boolean increasing, final Action action) {
this.detector = detector;
this.state = state;
this.resetState = resetState;
this.increasing = increasing;
this.action = action;
}
/** Get the event detector triggered.
* @return event detector triggered
*/
public EventDetector getEventDetector() {
return detector;
}
/** {@inheritDoc} */
@Override
public AbsoluteDate getDate() {
return state.getDate();
}
/** Get the triggering state.
* @return triggering state
* @see EventHandler#eventOccurred(SpacecraftState, EventDetector, boolean)
*/
public SpacecraftState getState() {
return state;
}
/** Get the reset state. Can be null if not stored.
* @return reset state
* @see EventHandler#resetState(EventDetector, SpacecraftState)
* @since 13.1
*/
public SpacecraftState getResetState() {
return resetState;
}
/** Get the Increasing/decreasing status of the event.
* @return increasing/decreasing status of the event
* @see EventHandler#eventOccurred(SpacecraftState, EventDetector, boolean)
*/
public boolean isIncreasing() {
return increasing;
}
/**
* Getter for the action from handler.
* @return action
* @since 14.0
*/
public Action getAction() {
return action;
}
}
/** Internal wrapper for events detectors. */
private class LoggingWrapper implements DetectorModifier {
/** Wrapped event detector. */
private final EventDetector wrappedDetector;
/** Simple constructor.
* @param detector events detector to wrap
*/
LoggingWrapper(final EventDetector detector) {
this.wrappedDetector = detector;
}
/** Log an event.
* @param state state at event trigger date
* @param resetState state after reset if any, otherwise event state and null if not logged
* @param increasing indicator if the event switching function was increasing
* @param action action from handler
*/
void logEvent(final SpacecraftState state, final SpacecraftState resetState, final boolean increasing,
final Action action) {
log.add(new LoggedEvent(getDetector(), state, resetState, increasing, action));
}
/** {@inheritDoc} */
@Override
public EventDetector getDetector() {
return wrappedDetector;
}
/** {@inheritDoc} */
@Override
public EventHandler getHandler() {
final EventHandler handler = getDetector().getHandler();
return new EventHandler() {
@Override
public void init(final SpacecraftState initialState, final AbsoluteDate target, final EventDetector detector) {
handler.init(initialState, target, getDetector());
}
/** {@inheritDoc} */
@Override
public Action eventOccurred(final SpacecraftState s, final EventDetector d, final boolean increasing) {
final Action action = handler.eventOccurred(s, getDetector(), increasing);
final boolean resettingState = action == Action.RESET_STATE;
logEvent(s, logResetStates && resettingState ? resetState(getDetector(), s) : null, increasing, action);
return action;
}
@Override
public SpacecraftState resetState(final EventDetector detector, final SpacecraftState oldState) {
return handler.resetState(getDetector(), oldState);
}
@Override
public void finish(final SpacecraftState finalState, final EventDetector detector) {
handler.finish(finalState, getDetector());
}
};
}
}
}