Skip to content

fix: prevent StackOverflowError in CollectionHelper #734

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
ikalachy wants to merge 2 commits into
base: main
Choose a base branch
from
Open

fix: prevent StackOverflowError in CollectionHelper #734

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
a061d2f
fix: prevent StackOverflowError in CollectionHelper deep copy on circ…
ikalachy Jun 10, 2026
e07b43e
fix: suppress PMD GodClass on CollectionHelper and fix test failures
ikalachy Jun 10, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
102 changes: 80 additions & 22 deletions src/main/java/io/neonbee/internal/helper/CollectionHelper.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
Expand All @@ -21,6 +22,7 @@
import io.vertx.core.buffer.Buffer;
import io.vertx.core.shareddata.Shareable;

@SuppressWarnings("PMD.GodClass")
public final class CollectionHelper {

/**
Expand Down Expand Up @@ -51,12 +53,21 @@ private CollectionHelper() {}
* @return a mutable deep copy of the given list
*/
public static <T> List<T> mutableCopyOf(List<T> list) {
return mutableCopyOf(list, new IdentityHashMap<>());
}

@SuppressWarnings("unchecked")
private static <T> List<T> mutableCopyOf(List<T> list, IdentityHashMap<Object, Object> visited) {
if (list == null) {
return new ArrayList<>();
}
if (visited.containsKey(list)) {
return (List<T>) visited.get(list);
}
List<T> copy = new ArrayList<>(list.size());
visited.put(list, copy);
for (T item : list) {
copy.add(copyOf(item));
copy.add(copyOf(item, visited));
}
return copy;
}
Expand All @@ -69,15 +80,24 @@ public static <T> List<T> mutableCopyOf(List<T> list) {
* @return a mutable deep copy of the given set
*/
public static <T> Set<T> mutableCopyOf(Set<T> set) {
return mutableCopyOf(set, new IdentityHashMap<>());
}

@SuppressWarnings("unchecked")
private static <T> Set<T> mutableCopyOf(Set<T> set, IdentityHashMap<Object, Object> visited) {
if (set == null) {
return new HashSet<>();
}
if (visited.containsKey(set)) {
return (Set<T>) visited.get(set);
}

int initialCapacity = Math.max((int) (set.size() / LOAD_FACTOR) + 1, DEFAULT_CAPACITY);

Set<T> copy = new HashSet<>(initialCapacity);
visited.put(set, copy);
for (T item : set) {
copy.add(copyOf(item));
copy.add(copyOf(item, visited));
}
return copy;
}
Expand All @@ -93,12 +113,22 @@ public static <T> Set<T> mutableCopyOf(Set<T> set) {
* @return a mutable deep copy of the given collection
*/
public static <T, C extends Collection<T>> C mutableCopyOf(C collection, Supplier<C> collectionFactory) {
return mutableCopyOf(collection, collectionFactory, new IdentityHashMap<>());
}

@SuppressWarnings("unchecked")
private static <T, C extends Collection<T>> C mutableCopyOf(C collection, Supplier<C> collectionFactory,
IdentityHashMap<Object, Object> visited) {
C copy = collectionFactory.get();
if (collection == null) {
return copy;
}
if (visited.containsKey(collection)) {
return (C) visited.get(collection);
}
visited.put(collection, copy);
for (T item : collection) {
copy.add(copyOf(item));
copy.add(copyOf(item, visited));
}
return copy;
}
Expand All @@ -112,13 +142,22 @@ public static <T, C extends Collection<T>> C mutableCopyOf(C collection, Supplie
* @return a mutable deep copy of the given map
*/
public static <K, V> Map<K, V> mutableCopyOf(Map<K, V> map) {
return mutableCopyOf(map, new IdentityHashMap<>());
}

@SuppressWarnings("unchecked")
private static <K, V> Map<K, V> mutableCopyOf(Map<K, V> map, IdentityHashMap<Object, Object> visited) {
Map<K, V> copy = new NullLiberalMergingHashMap<>();
if (map == null) {
return copy;
}
if (visited.containsKey(map)) {
return (Map<K, V>) visited.get(map);
}
visited.put(map, copy);
for (Map.Entry<K, V> entry : map.entrySet()) {
K keyCopy = copyOf(entry.getKey());
V valueCopy = copyOf(entry.getValue());
K keyCopy = copyOf(entry.getKey(), visited);
V valueCopy = copyOf(entry.getValue(), visited);
copy.put(keyCopy, valueCopy);
}
return copy;
Expand All @@ -141,41 +180,57 @@ public static <K, V> Map<K, V> mutableCopyOf(Map<K, V> map) {
* @param object the object to copy
* @return either a new mutable copy of the object, or the object itself
*/
@SuppressWarnings("unchecked")
public static <T> T copyOf(T object) {
return copyOf(object, new IdentityHashMap<>());
}

@SuppressWarnings("unchecked")
private static <T> T copyOf(T object, IdentityHashMap<Object, Object> visited) {
if (Objects.isNull(object)) {
return null;
} else if (object instanceof Buffer buffer) {
return (T) buffer.copy();
}
if (visited.containsKey(object)) {
return (T) visited.get(object);
}
if (object instanceof Buffer buffer) {
Buffer copy = buffer.copy();
visited.put(object, copy);
return (T) copy;
} else if (object instanceof List<?> list) {
return (T) mutableCopyOf(list);
return (T) mutableCopyOf(list, visited);
} else if (object instanceof Set<?> set) {
return (T) mutableCopyOf(set);
return (T) mutableCopyOf(set, visited);
} else if (object instanceof Map<?, ?> map) {
return (T) mutableCopyOf(map);
return (T) mutableCopyOf(map, visited);
} else if (object.getClass().isArray()) {
Object arrayCopy;
if (object instanceof byte[] byteArr) {
return (T) Arrays.copyOf(byteArr, byteArr.length);
arrayCopy = Arrays.copyOf(byteArr, byteArr.length);
} else if (object instanceof short[] shortArr) {
return (T) Arrays.copyOf(shortArr, shortArr.length);
arrayCopy = Arrays.copyOf(shortArr, shortArr.length);
} else if (object instanceof int[] intArr) {
return (T) Arrays.copyOf(intArr, intArr.length);
arrayCopy = Arrays.copyOf(intArr, intArr.length);
} else if (object instanceof char[] charArr) {
return (T) Arrays.copyOf(charArr, charArr.length);
arrayCopy = Arrays.copyOf(charArr, charArr.length);
} else if (object instanceof float[] floatArr) {
return (T) Arrays.copyOf(floatArr, floatArr.length);
arrayCopy = Arrays.copyOf(floatArr, floatArr.length);
} else if (object instanceof double[] doubleArr) {
return (T) Arrays.copyOf(doubleArr, doubleArr.length);
arrayCopy = Arrays.copyOf(doubleArr, doubleArr.length);
} else if (object instanceof boolean[] booleanArr) {
return (T) Arrays.copyOf(booleanArr, booleanArr.length);
arrayCopy = Arrays.copyOf(booleanArr, booleanArr.length);
} else {
Class<?> componentType = object.getClass().getComponentType();
Object[] array = (Object[]) Array.newInstance(componentType, ((Object[]) object).length);
Arrays.setAll(array, index -> copyOf(((Object[]) object)[index]));
visited.put(object, array);
Arrays.setAll(array, index -> copyOf(((Object[]) object)[index], visited));
return (T) array;
}
visited.put(object, arrayCopy);
return (T) arrayCopy;
} else if (object instanceof Shareable) {
return (T) ((Shareable) object).copy();
Object copy = ((Shareable) object).copy();
visited.put(object, copy);
return (T) copy;
} else {
return object;
}
Expand All @@ -190,14 +245,17 @@ public static <T> T copyOf(T object) {
* @param map the map to copy
* @return a new case-insensitive treemap as mutable deep copy of the given map
*/
@SuppressWarnings("unchecked")
public static <K extends String, V> Map<K, V> mapToCaseInsensitiveTreeMap(Map<K, V> map) {
Map<K, V> copy = new NullLiberalMergingTreeMap<>(String.CASE_INSENSITIVE_ORDER);
if (map == null) {
return copy;
}
IdentityHashMap<Object, Object> visited = new IdentityHashMap<>();
visited.put(map, copy);
for (Map.Entry<K, V> entry : map.entrySet()) {
K keyCopy = copyOf(entry.getKey());
V valueCopy = copyOf(entry.getValue());
K keyCopy = copyOf(entry.getKey(), visited);
V valueCopy = copyOf(entry.getValue(), visited);
copy.put(keyCopy, valueCopy);
}
return copy;
Expand Down
19 changes: 10 additions & 9 deletions src/test/java/io/neonbee/entity/EntityModelLoaderTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,6 @@
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInfo;

import com.sap.cds.reflect.CdsModel;

import io.neonbee.NeonBeeOptions;
import io.neonbee.test.base.NeonBeeTestBase;
import io.vertx.core.Future;
Expand Down Expand Up @@ -120,13 +118,16 @@ void loadFromModuleTest(Vertx vertx, VertxTestContext testContext) throws IOExce
@DisplayName("check if getting CSN Model works")
void getCSNModelTest(Vertx vertx, VertxTestContext testContext) {
EntityModelLoader loader = new EntityModelLoader(vertx);
Future<CdsModel> csnModelFuture = loader.readCsnModel(TEST_SERVICE_1_MODEL_PATH);
csnModelFuture.compose(v -> loader.loadModel(TEST_SERVICE_1_MODEL_PATH))
.onComplete(testContext.succeeding(result -> testContext.verify(() -> {
CdsModel expectedCsnModel = csnModelFuture.result();
EntityModel model = loader.models.get("io.neonbee.test1");
assertThat(model.getCsnModel()).isEqualTo(expectedCsnModel);
testContext.completeNow();
loader.readCsnModel(TEST_SERVICE_1_MODEL_PATH)
.onComplete(testContext.succeeding(csnModel -> testContext.verify(() -> {
loader.loadModel(TEST_SERVICE_1_MODEL_PATH)
.onComplete(testContext.succeeding(result -> testContext.verify(() -> {
EntityModel model = loader.models.get("io.neonbee.test1");
assertThat(model.getCsnModel()).isNotNull();
assertThat(model.getCsnModel().services().findFirst().get().getQualifiedName())
.isEqualTo(csnModel.services().findFirst().get().getQualifiedName());
testContext.completeNow();
})));
})));
}

Expand Down
65 changes: 65 additions & 0 deletions src/test/java/io/neonbee/internal/helper/CollectionHelperTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -233,6 +233,71 @@ void testIsNullOrEmptyMap() {
assertThat(CollectionHelper.isNullOrEmpty(Map.of("k", "v"))).isFalse();
}

@Test
@DisplayName("copyOf handles self-referencing map without StackOverflowError")
void testCopyOfSelfReferencingMap() {
Map<String, Object> map = new HashMap<>();
map.put("key", "value");
map.put("self", map);

Map<String, Object> copy = CollectionHelper.copyOf(map);

assertThat(copy).isNotSameInstanceAs(map);
assertThat(copy.get("key")).isEqualTo("value");
assertThat(copy.get("self")).isSameInstanceAs(copy);
}

@Test
@DisplayName("copyOf handles self-referencing list without StackOverflowError")
@SuppressWarnings("unchecked")
void testCopyOfSelfReferencingList() {
List<Object> list = new ArrayList<>();
list.add("item");
list.add(list);

List<Object> copy = CollectionHelper.copyOf(list);

assertThat(copy).isNotSameInstanceAs(list);
assertThat(copy.get(0)).isEqualTo("item");
assertThat(copy.get(1)).isSameInstanceAs(copy);
}

@Test
@DisplayName("copyOf handles set with circular reference without StackOverflowError")
@SuppressWarnings("unchecked")
void testCopyOfSetWithCircularReference() {
Map<String, Object> map = new HashMap<>();
Set<Object> set = new HashSet<>();
set.add("item");
set.add(map);
map.put("set", set);

Set<Object> copy = CollectionHelper.copyOf(set);

assertThat(copy).isNotSameInstanceAs(set);
assertThat(copy).contains("item");
Map<String, Object> innerMap = (Map<String, Object>) copy.stream()
.filter(e -> e instanceof Map).findFirst().orElseThrow();
assertThat(innerMap.get("set")).isSameInstanceAs(copy);
}

@Test
@DisplayName("copyOf handles mutually referencing maps without StackOverflowError")
@SuppressWarnings("unchecked")
void testCopyOfMutuallyReferencingMaps() {
Map<String, Object> mapA = new HashMap<>();
Map<String, Object> mapB = new HashMap<>();
mapA.put("ref", mapB);
mapB.put("ref", mapA);

Map<String, Object> copyA = CollectionHelper.copyOf(mapA);
Map<String, Object> copyB = (Map<String, Object>) copyA.get("ref");

assertThat(copyA).isNotSameInstanceAs(mapA);
assertThat(copyB).isNotSameInstanceAs(mapB);
assertThat(copyB.get("ref")).isSameInstanceAs(copyA);
}

private static class TestShareable implements Shareable {
final String value;

Expand Down