Fix community count computation for long based ids

Co-Authored-By: Paul Horn <paul.horn@neotechnology.com>
neo4j · Jul 28, 2020 · bd2cf24 · bd2cf24
1 parent 0c80df0
commit bd2cf24
Show file tree

Hide file tree

Showing 2 changed files with 19 additions and 1 deletion.
diff --git a/algo-common/src/main/java/org/neo4j/graphalgo/result/AbstractCommunityResultBuilder.java b/algo-common/src/main/java/org/neo4j/graphalgo/result/AbstractCommunityResultBuilder.java
@@ -100,7 +100,7 @@ private void buildCommunityCount() {
         long communityCount = 0L;
 
         SparseNodeMapping componentSizes = buildComponentSizes();
-        for (int communityId = 0; communityId < componentSizes.getCapacity(); communityId++) {
+        for (long communityId = 0; communityId < componentSizes.getCapacity(); communityId++) {
             long communitySize = componentSizes.get(communityId);
             if (communitySize > 0) {
                 communityCount++;

diff --git a/proc/common/src/test/java/org/neo4j/graphalgo/result/AbstractCommunityResultBuilderTest.java b/proc/common/src/test/java/org/neo4j/graphalgo/result/AbstractCommunityResultBuilderTest.java
@@ -176,6 +176,24 @@ void oneCommunityFromHugeMap() {
         assertEquals(4.0, histogram.getValueAtPercentile(100D), 0.01);
     }
 
+    @Test
+    void buildCommunityCountWithHugeCommunityCount() {
+        AbstractCommunityResultBuilder<Void> builder = builder(
+            procedureCallContext("communityCount"),
+            (maybeCommunityCount, maybeHistogram) -> {
+                assertTrue(maybeCommunityCount.isPresent());
+                assertFalse(maybeHistogram.isPresent());
+                long communityCount = maybeCommunityCount.orElse(-1);
+                assertEquals(2L, communityCount, "should build 2 communities");
+            });
+
+        LongUnaryOperator communityFunction = n -> n % 2 == 0 ? 0 : ((long) Integer.MAX_VALUE) + 2;
+        builder
+            .withCommunityFunction(communityFunction)
+            .withNodeCount(2)
+            .build();
+    }
+
     @Test
     void buildCommunityHistogramWithHugeCommunityCount() {
         AbstractCommunityResultBuilder<Void> builder = builder(