Add hdbscan in compute facade

Author: IoannisPanagiotas

algo/src/main/java/org/neo4j/gds/hdbscan/Labels.java

@@ -21,4 +21,7 @@
 
 import org.neo4j.gds.collections.ha.HugeLongArray;
 
-public record Labels(HugeLongArray labels, long numberOfNoisePoints, long numberOfClusters) {}
+public record Labels(HugeLongArray labels, long numberOfNoisePoints, long numberOfClusters) {
+
+    public static Labels EMPTY = new Labels(HugeLongArray.newArray(0),0, 0);
+}

algorithms-compute-facade/src/main/java/org/neo4j/gds/community/CommunityComputeFacade.java

@@ -34,6 +34,9 @@
 import org.neo4j.gds.conductance.ConductanceResult;
 import org.neo4j.gds.core.concurrency.DefaultPool;
 import org.neo4j.gds.core.utils.progress.JobId;
+import org.neo4j.gds.hdbscan.HDBScan;
+import org.neo4j.gds.hdbscan.HDBScanParameters;
+import org.neo4j.gds.hdbscan.Labels;
 import org.neo4j.gds.result.TimedAlgorithmResult;
 import org.neo4j.gds.termination.TerminationFlag;
 
@@ -162,4 +165,35 @@ CompletableFuture<TimedAlgorithmResult<ConductanceResult>> conductance(
         );
     }
 
+    CompletableFuture<TimedAlgorithmResult<Labels>> hdbscan(
+        Graph graph,
+        HDBScanParameters parameters,
+        JobId jobId,
+        boolean logProgress
+    ) {
+
+        if (graph.isEmpty()) {
+            return CompletableFuture.completedFuture(TimedAlgorithmResult.empty(Labels.EMPTY));
+        }
+
+        var progressTracker = progressTrackerFactory.create(
+            tasks.hdbscan(graph),
+            jobId,
+            parameters.concurrency(),
+            logProgress
+        );
+
+        var algorithm = new HDBScan(
+            graph,
+            graph.nodeProperties(parameters.nodeProperty()),
+            parameters,
+            progressTracker,
+            terminationFlag
+        );
+
+        return algorithmCaller.run(
+            algorithm::compute,
+            jobId
+        );
+    }
 }

algorithms-compute-facade/src/test/java/org/neo4j/gds/community/CommunityComputeFacadeEmptyGraphTest.java

@@ -34,6 +34,8 @@
 import org.neo4j.gds.conductance.ConductanceParameters;
 import org.neo4j.gds.conductance.ConductanceResult;
 import org.neo4j.gds.core.utils.progress.JobId;
+import org.neo4j.gds.hdbscan.HDBScanParameters;
+import org.neo4j.gds.hdbscan.Labels;
 import org.neo4j.gds.termination.TerminationFlag;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -114,4 +116,21 @@ void conductance(){
         verifyNoInteractions(algorithmCallerMock);
     }
 
+    @Test
+    void hdbscan(){
+
+        var future = facade.hdbscan(
+            graph,
+            mock(HDBScanParameters.class),
+            jobIdMock,
+            false
+        );
+
+        var results = future.join();
+
+        assertThat(results.result()).isEqualTo(Labels.EMPTY);
+        verifyNoInteractions(progressTrackerFactoryMock);
+        verifyNoInteractions(algorithmCallerMock);
+    }
+
 }

algorithms-compute-facade/src/test/java/org/neo4j/gds/community/CommunityComputeFacadeTest.java

@@ -39,6 +39,7 @@
 import org.neo4j.gds.extension.IdFunction;
 import org.neo4j.gds.extension.Inject;
 import org.neo4j.gds.extension.TestGraph;
+import org.neo4j.gds.hdbscan.HDBScanParameters;
 import org.neo4j.gds.logging.Log;
 import org.neo4j.gds.termination.TerminationFlag;
 
@@ -158,4 +159,25 @@ void conductance(){
         assertThat(results.result().globalAverageConductance()).isGreaterThan(0d);
         assertThat(results.computeMillis()).isNotNegative();
     }
+
+    @Test
+    void hdbscan(){
+        var future = facade.hdbscan(
+            graph,
+            new HDBScanParameters(
+                new Concurrency(4),
+                1,
+                3,
+                1,
+                "prop"
+            ),
+            jobIdMock,
+            false
+        );
+
+        var results = future.join();
+
+        assertThat(results.result().labels().toArray()).hasSize(3);
+        assertThat(results.computeMillis()).isNotNegative();
+    }
 }