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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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 */

/* @test

 * @bug 8133348

 * @summary Tests if reachabilityFence is working

 *

 * @run main/othervm -Xint                   -Dpremature=false ReachabilityFenceTest

 * @run main/othervm -XX:TieredStopAtLevel=1 -Dpremature=true  ReachabilityFenceTest

 * @run main/othervm -XX:TieredStopAtLevel=2 -Dpremature=true  ReachabilityFenceTest

 * @run main/othervm -XX:TieredStopAtLevel=3 -Dpremature=true  ReachabilityFenceTest

 * @run main/othervm -XX:TieredStopAtLevel=4 -Dpremature=true  ReachabilityFenceTest

 */

import java.lang.ref.Reference;

import java.util.concurrent.atomic.AtomicBoolean;

public class ReachabilityFenceTest {

    /*

     * Implementation notes:

     *

     * This test has positive and negative parts.

     *

     * Negative test is "nonFenced", and it tests that absent of reachabilityFence, the object can

     * be prematurely finalized -- this validates the test itself. Not every VM mode is expected to

     * prematurely finalize the objects, and -Dpremature option communicates that to test. If a VM mode

     * passes the negative test, then our understanding of what could happen is correct, and we can

     * go forward.

     *

     * Positive test is "fenced", and it checks that given the reachabilityFence at the end of the block,

     * the object cannot be finalized. There is no sense running a positive test when premature finalization

     * is not expected. It is a job for negative test to verify that invariant.

     *

     * The test methods should be appropriately compiled, therefore we do several iterations.

     */

    // Enough to OSR and compile

    static final int LOOP_ITERS = Integer.getInteger("LOOP_ITERS", 50000);

    // Enough after which to start triggering GC and finalization

    static final int WARMUP_LOOP_ITERS = LOOP_ITERS - Integer.getInteger("GC_ITERS", 100);

    // Enough to switch from an OSR'ed method to compiled method

    static final int MAIN_ITERS = 3;

    static final boolean PREMATURE_FINALIZATION = Boolean.getBoolean("premature");

    public static void main(String... args) {

        // Negative test

        boolean finalized = false;

        for (int c = 0; !finalized && c < MAIN_ITERS; c++) {

            finalized |= nonFenced();

        }

        if (PREMATURE_FINALIZATION && !finalized) {

            throw new IllegalStateException("The object had never been finalized before timeout reached.");

        }

        if (!PREMATURE_FINALIZATION && finalized) {

            throw new IllegalStateException("The object had been finalized without a fence, even though we don't expect it.");

        }

        if (!PREMATURE_FINALIZATION)

            return;

        // Positive test

        finalized = false;

        for (int c = 0; !finalized && c < MAIN_ITERS; c++) {

            finalized |= fenced();

        }

        if (finalized) {

            throw new IllegalStateException("The object had been prematurely finalized.");

        }

    }

    public static boolean nonFenced() {

        AtomicBoolean finalized = new AtomicBoolean();

        MyFinalizeable o = new MyFinalizeable(finalized);

        for (int i = 0; i < LOOP_ITERS; i++) {

            if (finalized.get()) break;

            if (i > WARMUP_LOOP_ITERS) {

                System.gc();

                System.runFinalization();

            }

        }

        return finalized.get();

    }

    public static boolean fenced() {

        AtomicBoolean finalized = new AtomicBoolean();

        MyFinalizeable o = new MyFinalizeable(finalized);

        for (int i = 0; i < LOOP_ITERS; i++) {

            if (finalized.get()) break;

            if (i > WARMUP_LOOP_ITERS) {

                System.gc();

                System.runFinalization();

            }

        }

        Reference.reachabilityFence(o);

        return finalized.get();

    }

    private static class MyFinalizeable {

        private final AtomicBoolean finalized;

        public MyFinalizeable(AtomicBoolean b) {

            this.finalized = b;

        }

        @Override

        protected void finalize() throws Throwable {

            super.finalize();

            finalized.set(true);

        }

    }

}