refactor: Add logging of wholes in the stop-index.

src/main/java/org/opentripplanner/transit/service/StopModelIndex.java

@@ -1,8 +1,11 @@
 package org.opentripplanner.transit.service;
 
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
+import javax.annotation.Nullable;
 import org.locationtech.jts.geom.Envelope;
 import org.opentripplanner.framework.collection.CollectionsView;
 import org.opentripplanner.framework.geometry.HashGridSpatialIndex;
@@ -12,6 +15,9 @@
 import org.opentripplanner.transit.model.site.RegularStop;
 import org.opentripplanner.transit.model.site.Station;
 import org.opentripplanner.transit.model.site.StopLocation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.slf4j.event.Level;
 
 /**
  * Indexed access to Stop entities.
@@ -20,6 +26,8 @@
  */
 class StopModelIndex {
 
+  private static final Logger LOG = LoggerFactory.getLogger(StopModelIndex.class);
+
   private final HashGridSpatialIndex<RegularStop> regularStopSpatialIndex = new HashGridSpatialIndex<>();
   private final Map<Station, MultiModalStation> multiModalStationForStations = new HashMap<>();
   private final HashGridSpatialIndex<AreaStop> locationIndex = new HashGridSpatialIndex<>();
@@ -58,6 +66,8 @@ class StopModelIndex {
     // Trim the sizes of the indices
     regularStopSpatialIndex.compact();
     locationIndex.compact();
+
+    logWholesInIndex();
   }
 
   /**
@@ -71,6 +81,7 @@ MultiModalStation getMultiModalStationForStation(Station station) {
     return multiModalStationForStations.get(station);
   }
 
+  @Nullable
   StopLocation stopByIndex(int index) {
     return stopsByIndex[index];
   }
@@ -82,4 +93,19 @@ int stopIndexSize() {
   Collection<AreaStop> findAreaStops(Envelope envelope) {
     return locationIndex.query(envelope);
   }
+
+  /**
+   * A small number of wholes in the stop-index is ok, but if there are many, it will affect
+   * the Raptor performance.
+   */
+  private void logWholesInIndex() {
+    int c = (int) Arrays.stream(stopsByIndex).filter(Objects::isNull).count();
+    if (c > 0) {
+      double p = (100.0 * c) / stopsByIndex.length;
+      // Log this as warning is more than 5% of the space is null
+      LOG
+        .atLevel(p >= 5.0 ? Level.WARN : Level.INFO)
+        .log("The stop index contains wholes in it. {} of {} is null.", c, stopsByIndex.length);
+    }
+  }
 }