/*

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file:

 *

 * Written by Martin Buchholz with assistance from members of JCP

 * JSR-166 Expert Group and released to the public domain, as

 * explained at http://creativecommons.org/publicdomain/zero/1.0/

 */

/*

 * @test

 * @bug 8054446 8137184 8137185

 * @summary Regression test for memory leak in remove(Object)

 */

import java.lang.reflect.AccessibleObject;

import java.lang.reflect.Array;

import java.lang.reflect.Field;

import java.lang.reflect.Modifier;

import java.util.ArrayDeque;

import java.util.Collection;

import java.util.Collections;

import java.util.IdentityHashMap;

import java.util.Set;

import java.util.concurrent.ArrayBlockingQueue;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ConcurrentLinkedDeque;

import java.util.concurrent.ConcurrentLinkedQueue;

import java.util.concurrent.LinkedBlockingDeque;

import java.util.concurrent.LinkedBlockingQueue;

import java.util.concurrent.LinkedTransferQueue;

import java.util.concurrent.PriorityBlockingQueue;

public class RemoveLeak {

    public static void main(String[] args) throws Throwable {

        new RemoveLeak().main();

    }

    void main() throws Throwable {

        test(new ConcurrentLinkedDeque());

        test(new ConcurrentLinkedQueue());

        test(new LinkedBlockingDeque(10));

        test(new LinkedBlockingQueue(10));

        test(new LinkedTransferQueue());

        test(new ArrayBlockingQueue(10));

        test(new PriorityBlockingQueue());

    }

    void test(Collection c) throws Throwable {

        assertNoLeak(c, () -> addRemove(c));

        // A demo that the leak detection infrastructure works

        // assertNoLeak(c, () -> c.add(1));

        // printRetainedObjects(c);

    }

    static void addRemove(Collection c) {

        c.add(1);

        c.remove(1);

    }

    // -------- leak detection infrastructure ---------------

    void assertNoLeak(Object root, Runnable r) {

        int prev = retainedObjects(root).size();

        for (int i = 0; i < 3; i++) {

            for (int j = 0; j < 3; j++) r.run();

            int next = retainedObjects(root).size();

            if (next <= prev)

                return;

            prev = next;

        }

        throw new AssertionError(

            String.format("probable memory leak in %s: %s",

                          root.getClass().getSimpleName(), root));

    }

    ConcurrentHashMap<Class<?>, Collection<Field>> classFields

        = new ConcurrentHashMap<Class<?>, Collection<Field>>();

    Collection<Field> referenceFieldsOf(Class<?> k) {

        Collection<Field> fields = classFields.get(k);

        if (fields == null) {

            fields = new ArrayDeque<Field>();

            ArrayDeque<Field> allFields = new ArrayDeque<Field>();

            for (Class<?> c = k; c != null; c = c.getSuperclass())

                for (Field field : c.getDeclaredFields())

                    if (!Modifier.isStatic(field.getModifiers())

                        && !field.getType().isPrimitive())

                        fields.add(field);

            AccessibleObject.setAccessible(

                fields.toArray(new AccessibleObject[0]), true);

            classFields.put(k, fields);

        }

        return fields;

    }

    static Object get(Field field, Object x) {

        try { return field.get(x); }

        catch (IllegalAccessException ex) { throw new AssertionError(ex); }

    }

    Set<Object> retainedObjects(Object x) {

        ArrayDeque<Object> todo = new ArrayDeque<Object>() {

            public void push(Object x) { if (x != null) super.push(x); }};

        Set<Object> uniqueObjects = Collections.newSetFromMap(

            new IdentityHashMap<Object, Boolean>());

        todo.push(x);

        while (!todo.isEmpty()) {

            Object y = todo.pop();

            if (uniqueObjects.contains(y))

                continue;

            uniqueObjects.add(y);

            Class<?> k = y.getClass();

            if (k.isArray() && !k.getComponentType().isPrimitive()) {

                for (int i = 0, len = Array.getLength(y); i < len; i++)

                    todo.push(Array.get(y, i));

            } else {

                for (Field field : referenceFieldsOf(k))

                    todo.push(get(field, y));

            }

        }

        return uniqueObjects;

    }

    /** for debugging the retained object graph */

    void printRetainedObjects(Object x) {

        for (Object y : retainedObjects(x))

            System.out.printf("%s : %s%n", y.getClass().getSimpleName(), y);

    }

}