org.opentripplanner.updater.trip.siri.SiriTripPatternCache Maven / Gradle / Ivy
package org.opentripplanner.updater.trip.siri;
import java.time.LocalDate;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;
import org.opentripplanner.transit.model.network.StopPattern;
import org.opentripplanner.transit.model.network.TripPattern;
import org.opentripplanner.transit.model.timetable.Trip;
/**
* Threadsafe mechanism for tracking any TripPatterns added to the graph via SIRI realtime messages.
* This tracks only patterns added by realtime messages, not ones that already existed from the
* scheduled NeTEx. This is a "cache" in the sense that it will keep returning the same TripPattern
* when presented with the same StopPattern, so if realtime messages add many trips passing through
* the same sequence of stops, they will all end up on this same TripPattern.
*
* Note that there are two versions of this class, this one for GTFS-RT and another for SIRI.
* See additional comments in the Javadoc of the GTFS-RT version of this class, whose name is
* simply TripPatternCache.
* TODO RT_AB: To the extent that double SIRI/GTFS implementations are kept, prefix all names
* with GTFS or SIRI or NETEX rather than having no prefix on the GTFS versions.
* TODO RT_TG: There is no clear strategy for what should be in the cache and the transit model and the flow
* between them. The NeTEx and a GTFS version of this should be merged. Having NeTex and GTFS
* specific indexes inside is ok. With the increased usage of DatedServiceJourneys, this should probably
* be part of the main model - not a separate cache. It is possible that this class works when it comes to
* the thread-safety, but just by looking at a few lines of code I see problems - a strategy needs to be
* analysed, designed and documented.
*/
class SiriTripPatternCache {
// TODO RT_AB: Improve documentation. This seems to be the primary collection of added
// TripPatterns, with other collections serving as indexes. Similar to TripPatternCache.cache
// in the GTFS version of this class, but with service date as part of the key.
private final Map cache = new HashMap<>();
// TODO RT_AB: generalize this so we can generate IDs for SIRI or GTFS-RT sources.
private final SiriTripPatternIdGenerator tripPatternIdGenerator;
private final Function getPatternForTrip;
/**
* TODO RT_AB: This class could potentially be reused for both SIRI and GTFS-RT, which may
* involve injecting a different ID generator and pattern fetching method.
*
* @param getPatternForTrip SiriTripPatternCache needs only this one feature of TransitService, so we retain
* only this function reference to effectively narrow the interface. This should also facilitate
* testing.
*/
public SiriTripPatternCache(
SiriTripPatternIdGenerator tripPatternIdGenerator,
Function getPatternForTrip
) {
this.tripPatternIdGenerator = tripPatternIdGenerator;
this.getPatternForTrip = getPatternForTrip;
}
/**
* Get cached trip pattern or create one if it doesn't exist yet.
*
* TODO RT_AB: Improve documentation and/or merge with GTFS version of this class.
* This was clearly derived from a method from TripPatternCache. This is the only non-dead-code
* public method on this class, and mirrors the only public method on the GTFS-RT version of
* TripPatternCache. It also explains why this class is called a "cache". It allows reusing the
* same TripPattern instance when many different trips are created or updated with the same pattern.
*
* @param stopPattern stop pattern to retrieve/create trip pattern
* @param trip Trip containing route of new trip pattern in case a new trip pattern will be
* created
* @return cached or newly created trip pattern
*/
public synchronized TripPattern getOrCreateTripPattern(
final StopPattern stopPattern,
final Trip trip,
LocalDate serviceDate
) {
TripPattern originalTripPattern = getPatternForTrip.apply(trip);
// TODO RT_AB: Verify implementation, which is different than the GTFS-RT version.
// It can return a TripPattern from the scheduled data, but protective copies are handled in
// TimetableSnapshot.update. Better document this aspect of the contract in this method's Javadoc.
if (originalTripPattern.getStopPattern().equals(stopPattern)) {
return originalTripPattern;
}
// Check cache for trip pattern
StopPatternServiceDateKey key = new StopPatternServiceDateKey(stopPattern, serviceDate);
TripPattern tripPattern = cache.get(key);
// Create TripPattern if it doesn't exist yet
if (tripPattern == null) {
var id = tripPatternIdGenerator.generateUniqueTripPatternId(trip);
tripPattern = TripPattern.of(id)
.withRoute(trip.getRoute())
.withMode(trip.getMode())
.withNetexSubmode(trip.getNetexSubMode())
.withStopPattern(stopPattern)
.withCreatedByRealtimeUpdater(true)
.withOriginalTripPattern(originalTripPattern)
.build();
// TODO: Add pattern to timetableRepository index?
// Add pattern to cache
cache.put(key, tripPattern);
}
return tripPattern;
}
}
// TODO RT_AB: move the below classes inside the above class as private static inner classes.
// Defining these additional classes in the same top-level class file is unconventional.
/**
* Serves as the key for the collection of TripPatterns added by realtime messages.
* Must define hashcode and equals to confer semantic identity.
* TODO RT_AB: clarify why each date has a different TripPattern instead of a different Timetable.
* It seems like there's a separate TripPattern instance for each StopPattern and service date,
* rather a single TripPattern instance associated with a separate timetable for each date.
*/
class StopPatternServiceDateKey {
StopPattern stopPattern;
LocalDate serviceDate;
public StopPatternServiceDateKey(StopPattern stopPattern, LocalDate serviceDate) {
this.stopPattern = stopPattern;
this.serviceDate = serviceDate;
}
@Override
public int hashCode() {
return stopPattern.hashCode() + serviceDate.hashCode();
}
@Override
public boolean equals(Object thatObject) {
if (!(thatObject instanceof StopPatternServiceDateKey)) {
return false;
}
StopPatternServiceDateKey that = (StopPatternServiceDateKey) thatObject;
return (this.stopPattern.equals(that.stopPattern) && this.serviceDate.equals(that.serviceDate));
}
}