Copilot commented on code in PR #2138:
URL: https://github.com/apache/maven-resolver/pull/2138#discussion_r4480596986
##########
maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectResult.java:
##########
@@ -37,9 +37,9 @@ public final class CollectResult {
private final CollectRequest request;
- private List<Exception> exceptions;
+ private final List<Exception> exceptions = new CopyOnWriteArrayList<>();
- private List<DependencyCycle> cycles;
+ private final List<DependencyCycle> cycles = new CopyOnWriteArrayList<>();
Review Comment:
The PR description says access is synchronized (`synchronize get/add`), but
the implementation uses `CopyOnWriteArrayList` instead of synchronization.
Please either (a) update the PR description to reflect the actual approach
(copy-on-write + unmodifiable views), or (b) change the implementation to
explicit synchronization to match the description.
##########
maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectResult.java:
##########
@@ -66,10 +64,10 @@ public CollectRequest getRequest() {
/**
* Gets the exceptions that occurred while building the dependency graph.
*
- * @return The exceptions that occurred, never {@code null}.
+ * @return An unmodifiable list of the exceptions that occurred, never
{@code null}.
*/
public List<Exception> getExceptions() {
- return exceptions;
+ return Collections.unmodifiableList(exceptions);
}
Review Comment:
Returning an unmodifiable list is a behavioral change: callers that
previously mutated the returned lists (e.g., `clear()`, `add(...)`) will now
get `UnsupportedOperationException`. If this API is consumed externally,
consider preserving backward compatibility by continuing to return a modifiable
thread-safe list (e.g., return the `CopyOnWriteArrayList` directly), or
introduce a new unmodifiable-view accessor while keeping the existing behavior
(and deprecate it if needed).
##########
maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectResult.java:
##########
@@ -18,9 +18,9 @@
*/
package org.eclipse.aether.collection;
-import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
Review Comment:
The PR description says access is synchronized (`synchronize get/add`), but
the implementation uses `CopyOnWriteArrayList` instead of synchronization.
Please either (a) update the PR description to reflect the actual approach
(copy-on-write + unmodifiable views), or (b) change the implementation to
explicit synchronization to match the description.
##########
maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectResult.java:
##########
@@ -18,9 +18,9 @@
*/
package org.eclipse.aether.collection;
Review Comment:
`CopyOnWriteArrayList` makes every `add(...)` copy the backing array, which
can become expensive if exceptions/cycles are recorded frequently.
Additionally, `Collections.unmodifiableList(...)` allocates a new wrapper on
every getter call. If write frequency can be non-trivial, consider using a
different concurrency strategy (e.g., `Collections.synchronizedList(new
ArrayList<>())` with appropriate locking) and/or cache the unmodifiable views
in final fields so the getters don't repeatedly allocate wrappers.
##########
maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectResult.java:
##########
@@ -37,9 +37,9 @@ public final class CollectResult {
private final CollectRequest request;
- private List<Exception> exceptions;
+ private final List<Exception> exceptions = new CopyOnWriteArrayList<>();
Review Comment:
`CopyOnWriteArrayList` makes every `add(...)` copy the backing array, which
can become expensive if exceptions/cycles are recorded frequently.
Additionally, `Collections.unmodifiableList(...)` allocates a new wrapper on
every getter call. If write frequency can be non-trivial, consider using a
different concurrency strategy (e.g., `Collections.synchronizedList(new
ArrayList<>())` with appropriate locking) and/or cache the unmodifiable views
in final fields so the getters don't repeatedly allocate wrappers.
##########
maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectResult.java:
##########
@@ -91,23 +86,20 @@ public CollectResult addException(Exception exception) {
/**
* Gets the dependency cycles that were encountered while building the
dependency graph.
*
- * @return The dependency cycles in the (raw) graph, never {@code null}.
+ * @return An unmodifiable list of the dependency cycles, never {@code
null}.
*/
public List<DependencyCycle> getCycles() {
- return cycles;
+ return Collections.unmodifiableList(cycles);
Review Comment:
`CopyOnWriteArrayList` makes every `add(...)` copy the backing array, which
can become expensive if exceptions/cycles are recorded frequently.
Additionally, `Collections.unmodifiableList(...)` allocates a new wrapper on
every getter call. If write frequency can be non-trivial, consider using a
different concurrency strategy (e.g., `Collections.synchronizedList(new
ArrayList<>())` with appropriate locking) and/or cache the unmodifiable views
in final fields so the getters don't repeatedly allocate wrappers.
##########
maven-resolver-api/src/main/java/org/eclipse/aether/collection/CollectResult.java:
##########
@@ -91,23 +86,20 @@ public CollectResult addException(Exception exception) {
/**
* Gets the dependency cycles that were encountered while building the
dependency graph.
*
- * @return The dependency cycles in the (raw) graph, never {@code null}.
+ * @return An unmodifiable list of the dependency cycles, never {@code
null}.
*/
public List<DependencyCycle> getCycles() {
- return cycles;
+ return Collections.unmodifiableList(cycles);
}
Review Comment:
Returning an unmodifiable list is a behavioral change: callers that
previously mutated the returned lists (e.g., `clear()`, `add(...)`) will now
get `UnsupportedOperationException`. If this API is consumed externally,
consider preserving backward compatibility by continuing to return a modifiable
thread-safe list (e.g., return the `CopyOnWriteArrayList` directly), or
introduce a new unmodifiable-view accessor while keeping the existing behavior
(and deprecate it if needed).
##########
maven-resolver-api/src/test/java/org/eclipse/aether/collection/CollectResultTest.java:
##########
@@ -0,0 +1,201 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.eclipse.aether.collection;
+
+import java.util.Iterator;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+import org.eclipse.aether.graph.DependencyCycle;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.mock;
+
+class CollectResultTest {
+
+ @Test
+ void testConcurrentAddException() throws Exception {
+ CollectResult result = new CollectResult(new CollectRequest());
+
+ int threads = 10;
+ int additionsPerThread = 100;
+
+ ExecutorService executor = Executors.newFixedThreadPool(threads);
+ CountDownLatch start = new CountDownLatch(1);
+
+ try {
+ Future<?>[] futures = new Future<?>[threads];
+
+ for (int i = 0; i < threads; i++) {
+ futures[i] = executor.submit(() -> {
+ start.await();
+
+ for (int j = 0; j < additionsPerThread; j++) {
+ result.addException(new Exception());
+ }
+ return null;
+ });
+ }
+
+ start.countDown();
+
+ for (Future<?> future : futures) {
+ future.get(30, TimeUnit.SECONDS);
+ }
+
+ assertEquals(threads * additionsPerThread,
result.getExceptions().size());
+ } finally {
+ executor.shutdownNow();
+ }
Review Comment:
Using `shutdownNow()` in tests can interrupt tasks and potentially mask
issues or introduce flakiness if execution timing changes. Prefer calling
`executor.shutdown()` and then `awaitTermination(...)` (with a bounded timeout)
to ensure clean termination without forced interruption, especially in
concurrency regression tests.
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