/*
 * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
 *
 * 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 RefprocSanity
 * @summary Test that null references/referents work fine
 *
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g                                                             RefprocSanity
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g -XX:+ShenandoahVerify                                       RefprocSanity
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g                       -XX:ShenandoahGCHeuristics=aggressive RefprocSanity
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g -XX:+ShenandoahVerify -XX:ShenandoahGCHeuristics=traversal  RefprocSanity
 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx1g -Xms1g                       -XX:ShenandoahGCHeuristics=traversal  RefprocSanity
 */

import java.lang.ref.*;

public class RefprocSanity {

  static final long TARGET_MB = Long.getLong("target", 10_000); // 10 Gb allocation
  static final int WINDOW = 10_000;

  static final Reference<MyObject>[] refs = new Reference[WINDOW];

  public static void main(String[] args) throws Exception {
    long count = TARGET_MB * 1024 * 1024 / 32;
    int rIdx = 0;

    ReferenceQueue rq = new ReferenceQueue();

    for (int c = 0; c < WINDOW; c++) {
      refs[c] = select(c, new MyObject(c), rq);
    }

    for (int c = 0; c < count; c++) {
      verifyRefAt(rIdx);
      refs[rIdx] = select(c, new MyObject(rIdx), rq);

      rIdx++;
      if (rIdx >= WINDOW) {
        rIdx = 0;
      }
      while (rq.poll() != null) {} // drain
    }
  }

  static Reference<MyObject> select(int v, MyObject ext, ReferenceQueue rq) {
    switch (v % 10) {
      case  0: return new SoftReference<MyObject>(null);
      case  1: return new SoftReference<MyObject>(null,  rq);
      case  2: return new SoftReference<MyObject>(ext);
      case  3: return new SoftReference<MyObject>(ext,  rq);

      case  4: return new WeakReference<MyObject>(null);
      case  5: return new WeakReference<MyObject>(null,  rq);
      case  6: return new WeakReference<MyObject>(ext);
      case  7: return new WeakReference<MyObject>(ext,  rq);

      case  8: return new PhantomReference<MyObject>(null, rq);
      case  9: return new PhantomReference<MyObject>(ext,  rq);

      default: throw new IllegalStateException();
    }
  }

  static void verifyRefAt(int idx) {
    Reference<MyObject> ref = refs[idx];
    MyObject mo = ref.get();
    if (mo != null && mo.x != idx) {
      throw new IllegalStateException("Referent tag is incorrect: " + mo.x + ", should be " + idx);
    }
  }

  static class MyObject {
    final int x;
    public MyObject(int x) { this.x = x; }
  }

}