/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */

import java.io.PrintStream;
import org.jikesrvm.mm.mminterface.MemoryManager;
import org.vmmagic.pragma.NoInline;

class Exhaust {

  private static final PrintStream o = System.out;

  static Object [] first;
  static Object [] last;
  static final int itemSize = 64;
  static double growthFactor = 10.0;
  static int rounds = 5;
  static long tot = 0;          // total # allocated
  static long wasAllocating;            // How much were we allocating?


  public static void main(String[] args) {
    long mhs = MemoryManager.getMaxHeapSize().toLong();

    o.println("Max heap size: " + mhs + " bytes");
    if (mhs > 1024 * 1024)
      o.println("  that's " + mhs / (1024.0 * 1024.0) + " megabytes");
    if (mhs > 1024 * 1024 * 1024)
      o.println("  that's " + mhs / (1024.0 * 1024 * 1024) + " gigabytes");
    runTest();

    System.exit(0);
  }

  @NoInline
  public static int doInner(int size) {
    while (true) {
      wasAllocating = size;
      Object [] next = new Object[size / 4];
      last[0] = next;
      last = next;
      tot += size;
      wasAllocating = 0;
    }
  }

  @NoInline
  public static void runTest() {
    int size = itemSize;
    for (int i = 1; i <= rounds; i++) {
      o.println("Starting round " + i + " with size = " + size);

      first = new Object[1];
      last = first;
      tot = 0;

      o.println("  Allocating until exception thrown");
      try {
        doInner(size);
      } catch (OutOfMemoryError e) {
        first = last = null;  // kills everything
        o.println("  Caught OutOfMemory - freeing now");  // this allocates; must follow nulling

        //        o.println("  Maximum size reached is " + size);

        o.println("  Had " + tot + " bytes allocated; failed trying to allocate " + wasAllocating + " bytes");
      }

      size *= growthFactor;
    }
    System.out.println("ALL TESTS PASSED");
  }
}