/*

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * @test

 * @bug 8059022

 * @modules java.base/jdk.internal.misc:+open

 * @summary Validate barriers after Unsafe getReference, CAS and swap (GetAndSet)

 * @requires vm.gc.Z & !vm.graal.enabled

 */

package compiler.gcbarriers;

import java.lang.reflect.Field;

import java.util.ArrayList;

import java.util.Random;

import sun.misc.Unsafe;

public class UnsafeIntrinsicsTest {

    /*

     * This test triggers the loadbarriers by allocating a lot, keeping the objects alive and then

     * letting them die in a way that maximizes fragmentation.

     *

     * All subtests (OperationType's) could run in parallel.

     */

    static int node_count = 133700;

    static int thread_count = 4;

    static int time = Integer.getInteger("time", 4); // seconds per subtest

    static Runner r = new Runner(null, 1, 1, Runner.OperationType.CAS);

    static Node first_node;

    int epoch = 0;

    public static void main(String[] args) {

        UnsafeIntrinsicsTest t = new UnsafeIntrinsicsTest();

        t.testWithLocalData(Runner.OperationType.CAS);

        t.testWithLocalData(Runner.OperationType.Weak_CAS);

        t.testWithLocalData(Runner.OperationType.CMPX);

        t.testWithSharedData(Runner.OperationType.Swap);

        t.testWithSharedData(Runner.OperationType.Load);

    }

    public UnsafeIntrinsicsTest() {

    }

    public void testWithLocalData(Runner.OperationType optype) {

        System.out.println("Testing " + optype.name() + " with " + thread_count +" thread and " + node_count + " nodes");

        // start mutator threads

        ArrayList<Thread> thread_list = new ArrayList<Thread>();

        Random r = new Random(System.nanoTime());

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

            setup(); // each thread has its own circle of nodes

            Thread t = new Thread(new Runner(first_node, time, r.nextLong(), optype));

            t.start();

            thread_list.add(t);

        }

        waitForCompletion(thread_list);

        countNodes();

    }

    public void testWithSharedData(Runner.OperationType optype) {

        System.out.println("Testing " + optype.name() + " with " + thread_count +" thread and " + node_count + " nodes");

        setup(); // All nodes are shared between threads

        ArrayList<Thread> thread_list = new ArrayList<Thread>();

        Random r = new Random(System.nanoTime());

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

            Thread t = new Thread(new Runner(first_node, time, r.nextLong(), optype));

            t.start();

            thread_list.add(t);

        }

        waitForCompletion(thread_list);

        countNodes();

    }

    public void waitForCompletion(ArrayList<Thread> thread_list) {

        // do some waiting

        try {

            Thread.sleep(time*1000);

        } catch (InterruptedException e) {

            e.printStackTrace();

        }

        // wait for all thread to terminate

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

            try {

                thread_list.get(i).join();

            } catch (InterruptedException e) {

                e.printStackTrace();

            }

        }

    }

    void countNodes() {

        epoch++;

        int count = 0;

        Node node = first_node;

        while (node.number() < epoch) {

            node.setNumber(epoch);

            count++;

            node = node.next();

        }

        System.out.println("Program end, found " + count + " nodes");

    }

    // Create a circular linked list

    public void setup() {

        first_node = new Node();

        Node last_node = first_node;

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

            last_node = new Node(last_node);

        }

        first_node.setNext(last_node);

    }

}

class Runner implements Runnable {

    OperationType type;

    Node current;

    Random r;

    long time;

    long seed;

    long milage = 0;

    long created = 0;

    long skipped = 0;

    int iterations = 0;

    static final jdk.internal.misc.Unsafe UNSAFE;

    static final long offset;

    public enum OperationType {

        Load("Load"),

        Swap("Swap"),

        CAS("CAS"),

        Weak_CAS("Weak-CAS"),

        CMPX("CMPX");

        private String name;

        private OperationType(String name) { this.name = name; }

    }

    static {

        try {

            Field f = jdk.internal.misc.Unsafe.class.getDeclaredField("theUnsafe");

            f.setAccessible(true);

            UNSAFE = (jdk.internal.misc.Unsafe) f.get(null);

            offset = UNSAFE.objectFieldOffset(Node.class.getDeclaredField("next"));

        } catch (Exception e) {

            throw new RuntimeException("Unable to get Unsafe instance.", e);

        }

    }

    public Runner(Node start, int testtime, long seed, OperationType type) {

        current = start;

        time = testtime*1000000000L;

        r = new Random(seed);

        this.type = type;

    }

    @Override

    public void run() {

        long starttime = System.nanoTime();

        while((System.nanoTime() - starttime) < time) {

            iterations++;

            // Run a bit

            int run_length = r.nextInt() & 0xfff;

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

                current = current.next();

                milage++;

            }

            // find a start node

            Node startNode = current;

            Node expectedNext = startNode.next;

            // Run a bit more

            int skip_length = (r.nextInt() & 0xff) + 1;

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

                current = current.next();

                skipped++;

            }

            // create a branch

            int branch_length = (r.nextInt() & 0xff) + 1;

            created += branch_length;

            Node head = makeBranch(current, branch_length);

            // complete circle, but continue to run on old path

            boolean test_fail = ((iterations & 0x1) == 0);

            Node current = merge(startNode, expectedNext, head, test_fail);

        }

        System.out.println("Milage: " + milage + " Skipped: " + skipped + " Created: " + created + " iterations: " + iterations);

    }

    /*

     *  The reason for the duplicated code that is wrapping the unsafe operations is that we want

     *  to test the operations individually. They must not interfere with each other - checking a field

     *  will heal that reference and no operation after can trigger the barrier.

     *

     *  All mergeImpl*-method are prevented from being inlined.

     */

    private Node merge(Node startNode, Node expectedNext, Node head, boolean test_fail) {

        switch (type) {

            case Load:

                return mergeImplLoad(startNode, expectedNext, head);

            case Swap:

                return mergeImplSwap(startNode, expectedNext, head);

            case CAS:

                if (test_fail) {

                    return mergeImplCASFail(startNode, expectedNext, head);

                } else {

                    return mergeImplCAS(startNode, expectedNext, head);

                }

            case Weak_CAS:

                if (test_fail) {

                    return mergeImplWeakCASFail(startNode, expectedNext, head);

                } else {

                    return mergeImplWeakCAS(startNode, expectedNext, head);

                }

            case CMPX:

                if (test_fail) {

                    return mergeImplCMPXFail(startNode, expectedNext, head);

                } else {

                    return mergeImplCMPX(startNode, expectedNext, head);

                }

            default:

            throw new Error("Unimplemented");

        }

    }

    private Node mergeImplLoad(Node startNode, Node expectedNext, Node head) {

        // Atomic load version

        Node temp = (Node) UNSAFE.getReference(startNode, offset);

        startNode.setNext(head);

        return temp;

    }

    private Node mergeImplSwap(Node startNode, Node expectedNext, Node head) {

        // Swap version

        return (Node) UNSAFE.getAndSetReference(startNode, offset, head);

    }

    private Node mergeImplCAS(Node startNode, Node expectedNext, Node head) {

        // CAS - should always be true within a single thread - no other thread can have overwritten

        if (!UNSAFE.compareAndSetReference(startNode, offset, expectedNext, head)) {

            throw new Error("CAS should always succeed on thread local objects, check you barrier implementation");

        }

        return expectedNext; // continue on old circle

    }

    private Node mergeImplCASFail(Node startNode, Node expectedNext, Node head) {

        // Force a fail

        if (UNSAFE.compareAndSetReference(startNode, offset, "fail", head)) {

            throw new Error("This CAS should always fail, check you barrier implementation");

        }

        if (startNode.next() != expectedNext) {

            throw new Error("Shouldn't have changed");

        }

        return current;

    }

    private Node mergeImplWeakCAS(Node startNode, Node expectedNext, Node head) {

        // Weak CAS - should always be true within a single thread - no other thread can have overwritten

        if (!UNSAFE.weakCompareAndSetReference(startNode, offset, expectedNext, head)) {

            throw new Error("Weak CAS should always succeed on thread local objects, check you barrier implementation");

        }

        return expectedNext; // continue on old circle

    }

    private Node mergeImplWeakCASFail(Node startNode, Node expectedNext, Node head) {

        // Force a fail

        if (UNSAFE.weakCompareAndSetReference(startNode, offset, "fail", head)) {

            throw new Error("This weak CAS should always fail, check you barrier implementation");

        }

        if (startNode.next() != expectedNext) {

            throw new Error("Shouldn't have changed");

        }

        return current;

    }

    private Node mergeImplCMPX(Node startNode, Node expectedNext, Node head) {

        // CmpX - should always be true within a single thread - no other thread can have overwritten

        Object res = UNSAFE.compareAndExchangeReference(startNode, offset, expectedNext, head);

        if (!res.equals(expectedNext)) {

            throw new Error("Fail CmpX should always succeed on thread local objects, check you barrier implementation");

        }

        return expectedNext; // continue on old circle

    }

    private Node mergeImplCMPXFail(Node startNode, Node expectedNext, Node head) {

        Object res = UNSAFE.compareAndExchangeReference(startNode, offset, head, head);

        if (startNode.next() != expectedNext) {

            throw new Error("Shouldn't have changed");

        }

        if (head == expectedNext) {

            throw new Error("Test malfunction");

        }

        if (!res.equals(expectedNext)) {

            throw new Error("This CmpX should have returned 'expectedNext' when it failed");

        }

        if (res.equals(head)) {

            throw new Error("This CmpX shouldn't have returned head when it failed. count: "+ iterations);

        }

        return current;

    }

    // Create a new branch that will replace a part of the circle

    public Node makeBranch(Node end_node, int count) {

        Node head = end_node;

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

            head = new Node(head);

        }

        return head;

    }

}

class Node {

    Node next;

    int number = 0;

    public int number() {

        return number;

    }

    public void setNumber(int v) {

        number = v;

    }

    public Node() {

    }

    public Node(Node link) {

        next = link;

    }

    public void setNext(Node next) {

        this.next = next;

    }

    public Node next() {

        return next;

    }

}