guava-testlib/test/com/google/common/testing/GcFinalizationTest.java - master - githubmirror/guava

guava-testlib/test/com/google/common/testing/GcFinalizationTest.java
280 строк9 KB
cpovirk
Adapt to the once and future TODO style.
28 июл 2026, 23:37
28 июл 2026, 23:373b1c731
/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed 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 com.google.common.testing;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertThrows;
import static org.junit.Assert.assertTrue;

import com.google.common.util.concurrent.SettableFuture;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.WeakHashMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;
import org.junit.Test;

/**
 * Tests for {@link GcFinalization}.
 *
 * @author Martin Buchholz
 * @author mike nonemacher
 */
@NullUnmarked
public class GcFinalizationTest {

  // ----------------------------------------------------------------
  // Ordinary tests of successful method execution
  // ----------------------------------------------------------------

  @Test
  public void await_countDownLatch() {
    CountDownLatch latch = new CountDownLatch(1);
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/487687332
          @Override
          protected void finalize() {
            latch.countDown();
          }
        };
    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.await(latch);
    assertEquals(0, latch.getCount());
  }

  @Test
  public void awaitDone_future() {
    SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/487687332
          @Override
          protected void finalize() {
            future.set(null);
          }
        };
    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.awaitDone(future);
    assertTrue(future.isDone());
    assertFalse(future.isCancelled());
  }

  @Test
  public void awaitDone_future_cancel() {
    SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/487687332
          @Override
          protected void finalize() {
            future.cancel(false);
          }
        };
    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.awaitDone(future);
    assertTrue(future.isDone());
    assertTrue(future.isCancelled());
  }

  @Test
  public void awaitClear() {
    WeakReference<Object> ref = createWeakReference();
    GcFinalization.awaitClear(ref);
    assertThat(ref.get()).isNull();
  }

  private WeakReference<Object> createWeakReference() {
    return new WeakReference<>(new Object());
  }

  @Test
  public void awaitDone_finalizationPredicate() {
    WeakHashMap<Object, Object> map = new WeakHashMap<>();
    map.put(new Object(), Boolean.TRUE);
    GcFinalization.awaitDone(map::isEmpty);
    assertTrue(map.isEmpty());
  }

  // ----------------------------------------------------------------
  // Test that interrupts result in RuntimeException, not InterruptedException.
  // Trickier than it looks, because runFinalization swallows interrupts.
  // ----------------------------------------------------------------

  static final class Interruptenator extends Thread {
    final AtomicBoolean shutdown;

    Interruptenator(Thread interruptee) {
      this(interruptee, new AtomicBoolean(false));
    }

    @SuppressWarnings("ThreadPriorityCheck") // TODO(b/175898629): Consider onSpinWait.
    Interruptenator(Thread interruptee, AtomicBoolean shutdown) {
      super(
          () -> {
            while (!shutdown.get()) {
              interruptee.interrupt();
              Thread.yield();
            }
          });
      this.shutdown = shutdown;
      start();
    }

    @SuppressWarnings("ThreadPriorityCheck") // TODO(b/175898629): Consider onSpinWait.
    void shutdown() {
      shutdown.set(true);
      while (this.isAlive()) {
        Thread.yield();
      }
    }
  }

  void assertWrapsInterruptedException(RuntimeException e) {
    assertThat(e).hasMessageThat().contains("Unexpected interrupt");
    assertThat(e).hasCauseThat().isInstanceOf(InterruptedException.class);
  }

  @Test
  public void await_countDownLatch_interrupted() {
    Interruptenator interruptenator = new Interruptenator(Thread.currentThread());
    try {
      CountDownLatch latch = new CountDownLatch(1);
      RuntimeException expected =
          assertThrows(RuntimeException.class, () -> GcFinalization.await(latch));
      assertWrapsInterruptedException(expected);
    } finally {
      interruptenator.shutdown();
      Thread.interrupted();
    }
  }

  @Test
  public void awaitDone_future_interrupted_interrupted() {
    Interruptenator interruptenator = new Interruptenator(Thread.currentThread());
    try {
      SettableFuture<@Nullable Void> future = SettableFuture.create();
      RuntimeException expected =
          assertThrows(RuntimeException.class, () -> GcFinalization.awaitDone(future));
      assertWrapsInterruptedException(expected);
    } finally {
      interruptenator.shutdown();
      Thread.interrupted();
    }
  }

  @Test
  public void awaitClear_interrupted() {
    Interruptenator interruptenator = new Interruptenator(Thread.currentThread());
    Foo foo = new Foo();
    try {
      WeakReference<Object> ref = new WeakReference<>(foo);
      RuntimeException expected =
          assertThrows(RuntimeException.class, () -> GcFinalization.awaitClear(ref));
      assertWrapsInterruptedException(expected);
    } finally {
      reachabilityFence(foo);
      interruptenator.shutdown();
      Thread.interrupted();
    }
  }

  private static final class Foo {}

  @Test
  public void awaitDone_finalizationPredicate_interrupted() {
    Interruptenator interruptenator = new Interruptenator(Thread.currentThread());
    try {
      RuntimeException expected =
          assertThrows(RuntimeException.class, () -> GcFinalization.awaitDone(() -> false));
      assertWrapsInterruptedException(expected);
    } finally {
      interruptenator.shutdown();
      Thread.interrupted();
    }
  }

  /**
   * awaitFullGc() is not quite as reliable a way to ensure calling of a specific finalize method as
   * the more direct await* methods, but should be reliable enough in practice to avoid flakiness of
   * this test. (And if it isn't, we'd like to know about it first!)
   */
  @Test
  public void awaitFullGc() {
    CountDownLatch finalizerRan = new CountDownLatch(1);
    WeakReference<Object> ref = createWeakReferenceWithFinalizer(finalizerRan);

    // Don't copy this into your own test!
    // Use e.g. awaitClear or await(CountDownLatch) instead.
    GcFinalization.awaitFullGc();

    // Attempt to help with some flakiness that we've seen: b/387521512.
    GcFinalization.awaitFullGc();

    assertEquals(0, finalizerRan.getCount());
    assertThat(ref.get()).isNull();
  }

  private WeakReference<Object> createWeakReferenceWithFinalizer(CountDownLatch finalizerRan) {
    return new WeakReference<>(
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/487687332
          @Override
          protected void finalize() {
            finalizerRan.countDown();
          }
        });
  }

  // We call the method only after checking that it's present.
  @IgnoreJRERequirement
  @SuppressWarnings({
    "Java8ApiChecker",
    // This method is a helper, which we call from a `finally` block, as recommended.
    "ReachabilityFenceUsage",
  })
  static void reachabilityFence(@Nullable Object o) {
    if (IS_REACHABILITY_FENCE_METHOD_USABLE) {
      Reference.reachabilityFence(o);
    }
  }

  private static final boolean IS_REACHABILITY_FENCE_METHOD_USABLE =
      computeIsReachabilityFenceMethodUsable();

  private static boolean computeIsReachabilityFenceMethodUsable() {
    try {
      Method method = Reference.class.getMethod("reachabilityFence", Object.class);
      method.invoke(null, GcFinalizationTest.class); // to make sure the method is accessible
      return true;
    } catch (NoSuchMethodException | IllegalAccessException probablyBeforeJava9OrAndroid28) {
      /*
       * It's theoretically possible for Reference.reachabilityFence to exist under older VMs in an
       * inaccessible form.
       */
      return false;
    } catch (InvocationTargetException e) {
      throw new AssertionError(e.getCause());
    }
  }
}