Use object pooling instead of threadlocal

src/main/java/org/entur/lamassu/service/impl/GeoUtils.java

@@ -18,6 +18,8 @@
 
 package org.entur.lamassu.service.impl;
 
+import java.util.LinkedList;
+import java.util.Queue;
 import org.entur.lamassu.service.BoundingBoxQueryParameters;
 import org.entur.lamassu.service.RangeQueryParameters;
 import org.geotools.api.referencing.operation.TransformException;
@@ -30,6 +32,7 @@
 import org.locationtech.jts.geom.CoordinateXY;
 
 public class GeoUtils {
+
  private GeoUtils() {}
 
  /**
@@ -78,28 +81,53 @@ private GeoUtils() {}
  * @return
  */
  private static double getDiameter(ReferencedEnvelope envelope) {
+ double distance = 0.0;
  try {
- GeodeticCalculator gc = GeodeticCalculatorSingleton.getInstance();
+ GeodeticCalculator gc = GeodeticCalculatorPoolManager.get();
  Coordinate start = new CoordinateXY(envelope.getMinX(), envelope.getMinY());
  Coordinate end = new CoordinateXY(envelope.getMaxX(), envelope.getMaxY());
  gc.setStartingPosition(JTS.toDirectPosition(start, DefaultGeographicCRS.WGS84));
  gc.setDestinationPosition(JTS.toDirectPosition(end, DefaultGeographicCRS.WGS84));
- return gc.getOrthodromicDistance();
+ distance = gc.getOrthodromicDistance();
+ GeodeticCalculatorPoolManager.release(gc);
  } catch (TransformException e) {
  throw new IllegalArgumentException(e);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ }
+
+ if (distance == 0.0) {
+ throw new IllegalStateException();
  }
+
+ return distance;
  }
 
- // GeodeticCalculator not thread-safe, so we make thread-local singletons
- private static class GeodeticCalculatorSingleton {
+ private static class GeodeticCalculatorPoolManager {
 
- private GeodeticCalculatorSingleton() {}
+ private static final Queue<GeodeticCalculator> QUEUE = new LinkedList<>();
+ private static final int POOL_SIZE = 10;
 
- private static final ThreadLocal<GeodeticCalculator> _threadLocal =
- ThreadLocal.withInitial(() -> new GeodeticCalculator(DefaultGeographicCRS.WGS84));
+ static {
+ for (int i = 0; i < POOL_SIZE; i++) {
+ QUEUE.add(new GeodeticCalculator(DefaultGeographicCRS.WGS84));
+ }
+ }
+
+ private static GeodeticCalculator get() throws InterruptedException {
+ synchronized (QUEUE) {
+ while (QUEUE.isEmpty()) {
+ QUEUE.wait();
+ }
+ return QUEUE.poll();
+ }
+ }
 
- public static GeodeticCalculator getInstance() {
- return _threadLocal.get();
+ private static void release(GeodeticCalculator gc) {
+ synchronized (QUEUE) {
+ QUEUE.offer(gc);
+ QUEUE.notifyAll();
+ }
  }
  }
 }