luni/src/test/java/libcore/java/lang/ref/FinalizeTest.java

/*
 * Copyright (C) 2011 Google Inc.
 *
 * 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 libcore.java.lang.ref;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import junit.framework.TestCase;

public final class FinalizeTest extends TestCase {

    public void testFinalizeIsCalled() throws Exception {
        AtomicBoolean finalized = new AtomicBoolean();
        createFinalizableObject(finalized);

        FinalizationTester.induceFinalization();
        if (!finalized.get()) {
            fail("object not yet finalized");
        }
    }

    /**
     * Test verifies that runFinalization() does not mess up objects
     * that should be finalized later on. http://b/6907299
     */
    public void testInducedFinalization() throws Exception {
        AtomicBoolean finalized1 = new AtomicBoolean();
        AtomicBoolean finalized2 = new AtomicBoolean();
        createFinalizableObject(finalized1);
        createFinalizableObject(finalized2);
        FinalizationTester.induceFinalization();
        if (!finalized1.get() || !finalized2.get()) {
            fail("not yet finalized: " + finalized1.get() + " " + finalized2.get());
        }
    }

    /** Do not inline this method; that could break non-precise GCs. See FinalizationTester. */
    private X createFinalizableObject(final AtomicBoolean finalized) {
        X result = new X() {
            @Override protected void finalize() throws Throwable {
                super.finalize();
                finalized.set(true);
            }
        };
        FinalizationTester.induceFinalization();
        // Dance around a bit to discourage dx from realizing that 'result' is no longer live.
        boolean wasFinalized = finalized.get();
        if (wasFinalized) {
            fail("finalizer called early"); // ...because 'result' is still live until we return.
        }
        // But we don't actually want to return 'result' because then we'd have to worry about
        // the caller accidentally keeping it live.
        return wasFinalized ? result : null;
    }

    static class X {}

    // Helper function since we do not want a vreg to keep the allocated object live.
    // For b/25851249
    private void exceptionInConstructor() {
        try {
            new ConstructionFails();
        } catch (AssertionError expected) {
        }
    }

    // http://b/issue?id=2136462
    public void testBackFromTheDead() throws Exception {
        exceptionInConstructor();
        FinalizationTester.induceFinalization();
        assertTrue("object whose constructor threw was not finalized", ConstructionFails.finalized);
    }

    static class ConstructionFails {
        private static boolean finalized;

        ConstructionFails() {
            throw new AssertionError();
        }

        @Override protected void finalize() throws Throwable {
            finalized = true;
        }
    }

    /**
     * The finalizer watch dog exits the VM if any object takes more than 10 s
     * to finalize. Check that objects near that limit are okay.
     */
    public void testWatchdogDoesNotFailForObjectsThatAreNearTheDeadline() throws Exception {
        CountDownLatch latch = new CountDownLatch(5);
        createSlowFinalizer(   1, latch);
        createSlowFinalizer(1000, latch);
        createSlowFinalizer(2000, latch);
        createSlowFinalizer(4000, latch);
        createSlowFinalizer(8000, latch);
        FinalizationTester.induceFinalization();
        latch.await();
    }

    public void createSlowFinalizer(final long millis, final CountDownLatch latch) {
        new Object() {
            @Override protected void finalize() throws Throwable {
                System.out.println("finalize sleeping " + millis + " ms");
                Thread.sleep(millis);
                latch.countDown();
            }
        };
    }

    /**
     * Make sure that System.runFinalization() returns even if the finalization
     * queue is never completely empty. http://b/4193517
     */
    public void testSystemRunFinalizationReturnsEvenIfQueueIsNonEmpty() throws Exception {
        AtomicInteger count = new AtomicInteger();
        AtomicBoolean keepGoing = new AtomicBoolean(true);
        createChainedFinalizer(count, keepGoing);
        FinalizationTester.induceFinalization();
        keepGoing.set(false);
        assertTrue(count.get() > 0);
    }

    public void createChainedFinalizer(final AtomicInteger counter, final AtomicBoolean keepGoing) {
        new Object() {
            @Override protected void finalize() throws Throwable {
                int count = counter.incrementAndGet();
                System.out.println(count);
                if (keepGoing.get()) {
                    createChainedFinalizer(counter, keepGoing); // recursive!
                }
                System.gc();
                FinalizationTester.enqueueReferences();
            }
        };
    }
}