Merge pull request #742 from Netflix/250618.throw-null-ptr-null-pkey

throw null ptr exception when constructing null pkey idx

Author: kvoli

hollow/src/main/java/com/netflix/hollow/core/index/HollowPrimaryKeyIndex.java

@@ -625,6 +625,7 @@ private int fieldHash(int ordinal, int fieldIdx) {
         HollowObjectTypeReadState typeState = this.typeState;
         HollowObjectSchema schema = typeState.getSchema();
 
+        int parentOrdinal = ordinal;
         int lastFieldPath = fieldPathIndexes[fieldIdx].length - 1;
         for(int i=0;i<lastFieldPath;i++) {
             int fieldPosition = fieldPathIndexes[fieldIdx][i];
@@ -633,6 +634,13 @@ private int fieldHash(int ordinal, int fieldIdx) {
             schema = typeState.getSchema();
         }
 
+        if (ordinal == ORDINAL_NONE) {
+            HollowObjectSchema parentSchema =  this.typeState.getSchema();
+            throw new NullPointerException("Cannot hash null field " +
+                    parentSchema.getFieldName(fieldIdx) + " in type " +
+                    parentSchema.getName() + " at ordinal " + parentOrdinal);
+        }
+
         int hashCode = HollowReadFieldUtils.fieldHashCode(typeState, ordinal, fieldPathIndexes[fieldIdx][lastFieldPath]);
 
         switch(fieldTypes[fieldIdx]) {

hollow/src/test/java/com/netflix/hollow/core/index/HollowPrimaryKeyIndexTest.java

@@ -335,6 +335,19 @@ public void testNotBindable() throws IOException {
         Assert.assertEquals(0, validPki.getMatchingOrdinal(1L));
     }
 
+
+    @Test
+    public void testNullPKeyIdx() throws IOException {
+        HollowObjectMapper mapper = new HollowObjectMapper(writeStateEngine);
+        mapper.add(new TypeNullPKey());
+        roundTripSnapshot();
+
+        try {
+            HollowPrimaryKeyIndex invalidPkIdx = new HollowPrimaryKeyIndex(this.readStateEngine, "TypeNullPKey", "id");
+            fail("Index on type with null fields is expected to fail construction");
+        } catch (NullPointerException e) {}
+    }
+
     private static void addDataForDupTesting(HollowWriteStateEngine writeStateEngine, int a1Start, double a2, int size) {
         TypeB typeB = new TypeB("commonTypeB");
         HollowObjectMapper mapper = new HollowObjectMapper(writeStateEngine);
@@ -380,6 +393,15 @@ public TypeB(String b1, boolean isDuplicate) {
         }
     }
 
+    @HollowPrimaryKey(fields = {"id"})
+    private static class TypeNullPKey {
+        private final Long id;
+
+        public TypeNullPKey() {
+            this.id = null;
+        }
+    }
+
     @Override
     protected void initializeTypeStates() { }