Transfer smallest update to correct place :see_no_evil

Author: IoannisPanagiotas

algo/src/main/java/org/neo4j/gds/steiner/SteinerBasedDeltaStepping.java

@@ -198,6 +198,7 @@ private boolean ensureShortest(
                 .min()
                 .orElseThrow();
             //return true if the closet terminal is at least as close as the  closest next node
+            System.out.println("hi" + distance + " " + currentMinDistance + " " + (distance <= currentMinDistance) + " " + oldBin + " " + currentBin);
             return distance <= currentMinDistance;
         } else {
             return (distance < currentBin * delta);

algo/src/main/java/org/neo4j/gds/steiner/SteinerBasedDeltaTask.java

@@ -138,7 +138,6 @@ private void relaxNode(long nodeId) {
         graph.forEachRelationship(nodeId, 1.0, (sourceNodeId, targetNodeId, weight) -> {
             if (!mergedToSource.get(targetNodeId)) { //ignore merged vertices
                 tryToUpdate(sourceNodeId, targetNodeId, weight);
-                smallestConsideredDistance = Math.min(weight, smallestConsideredDistance);
             }
             return true;
         });
@@ -165,6 +164,8 @@ private void tryToUpdate(long sourceNodeId, long targetNodeId,double weight) {
             // CAX failed, retry
             oldDist = witness;
         }
+        smallestConsideredDistance = Math.min(newDist, smallestConsideredDistance);
+
         if (uninvisitedTerminal.get(targetNodeId)) {
 
             terminalQueueLock.lock();

algo/src/test/java/org/neo4j/gds/steiner/ShortestPathSteinerAlgorithmExtendedTest.java

@@ -21,6 +21,8 @@
 
 import com.carrotsearch.hppc.BitSet;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 import org.neo4j.gds.Orientation;
 import org.neo4j.gds.core.concurrency.Pools;
 import org.neo4j.gds.core.utils.progress.tasks.ProgressTracker;
@@ -138,15 +140,19 @@ class ShortestPathSteinerAlgorithmExtendedTest {
     @Inject
     private IdFunction triangleIdFunction;
 
-    @Test
-    void shouldWorkCorrectly() {
+    @ParameterizedTest
+    @ValueSource(doubles = {2.0, 5.0, 100.0})
+        //2.0 is the standard one we use everything
+        //5.0 is one such that we can deduce a2 is best without changing bucket
+        //100.0 is a big one where everything takes place inside a single bucket
+    void shouldWorkCorrectly(double delta) {
 
         var a = SteinerTestUtils.getNodes(idFunction, 6);
         var steinerTreeResult = new ShortestPathsSteinerAlgorithm(
             graph,
             a[0],
             List.of(a[2], a[5]),
-            2.0,
+            delta,
             1,
             false,
             Pools.DEFAULT