/*
 * Copyright (c) 2017, Google and/or its affiliates. All rights reserved.
 * 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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 * questions.
 */

package MyPackage;

/**
 * @test
 * @summary Verifies the JVMTI Heap Monitor stack depth handling.
 * @build Frame HeapMonitor
 * @compile HeapMonitorStackDepthTest.java
 * @run main/othervm/native -agentlib:HeapMonitor MyPackage.HeapMonitorStackDepthTest
 */

public class HeapMonitorStackDepthTest {
  private native static double getAverageStackDepth();

  private static double calculateErrorPercentage(double expected, double actual) {
    double error = expected - actual;
    error = error < 0 ? -error : error;
    return error / expected * 100;
  }

  public static void main(String[] args) {
    int[] depths = {10, 100, 500};

    for (int depthIdx = 0; depthIdx < depths.length; depthIdx++) {
      int depth = depths[depthIdx];

      HeapMonitor.enableSampling();
      HeapMonitor.allocate(depth);
      HeapMonitor.disableSampling();

      // baseDepth represents the helper method depth: main, finalWrapper, and helper.
      // To get the requested depth, remove this from the count.
      final int baseDepth = 3;
      double averageDepth = getAverageStackDepth() - baseDepth;
      double errorPercentage = calculateErrorPercentage(depth, averageDepth);

      // 1% error should be close enough.
      if (errorPercentage > 1) {
        throw new RuntimeException("Stack depth average over 5% for depth " + depth + " : " + averageDepth + " , error: " + errorPercentage);
      }
    }

    // Last test is 1024, which is the current maximum.
    HeapMonitor.enableSampling();
    final int maximumDepth = 1024;
    HeapMonitor.allocate(1024);
    HeapMonitor.disableSampling();
    // Because of the extra frames, we should be at (maximumDepth + a few frames). Due to the
    // maximum depth allowed, we hit it and so should still be at an average of 1024.
    double averageDepth = getAverageStackDepth();
    double errorPercentage = calculateErrorPercentage(maximumDepth, averageDepth);

    // 1% error should be close enough.
    if (errorPercentage > 1) {
      throw new RuntimeException("Stack depth average over 5% for depth 1024 : " + averageDepth + " , error: " + errorPercentage);
    }
  }
}