/*

 * Copyright (c) 2016, Oracle 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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 */

#include "precompiled.hpp"

#include "gc/g1/g1Predictions.hpp"

#include "unittest.hpp"

static const double epsilon = 1e-6;

// Some basic formula tests with confidence = 0.0

TEST_VM(G1Predictions, basic_predictions) {

  G1Predictions predictor(0.0);

  TruncatedSeq s;

  double p0 = predictor.get_new_prediction(&s);

  ASSERT_LT(p0, epsilon) << "Initial prediction of empty sequence must be 0.0";

  s.add(5.0);

  double p1 = predictor.get_new_prediction(&s);

  ASSERT_NEAR(p1, 5.0, epsilon);

  for (int i = 0; i < 40; i++) {

    s.add(5.0);

  }

  double p2 = predictor.get_new_prediction(&s);

  ASSERT_NEAR(p2, 5.0, epsilon);

}

// The following tests checks that the initial predictions are based on

// the average of the sequence and not on the stddev (which is 0).

TEST_VM(G1Predictions, average_not_stdev_predictions) {

  G1Predictions predictor(0.5);

  TruncatedSeq s;

  s.add(1.0);

  double p1 = predictor.get_new_prediction(&s);

  ASSERT_GT(p1, s.davg()) << "First prediction must be greater than average";

  s.add(1.0);

  double p2 = predictor.get_new_prediction(&s);

  ASSERT_GT(p1, p2) << "First prediction must be greater than second";

  s.add(1.0);

  double p3 = predictor.get_new_prediction(&s);

  ASSERT_GT(p2, p3) << "Second prediction must be greater than third";

  s.add(1.0);

  s.add(1.0); // Five elements are now in the sequence.

  double p4 = predictor.get_new_prediction(&s);

  ASSERT_LT(p4, p3) << "Fourth prediction must be smaller than third";

  ASSERT_NEAR(p4, 1.0, epsilon);

}

// The following tests checks that initially prediction based on

// the average is used, that gets overridden by the stddev prediction at

// the end.

TEST_VM(G1Predictions, average_stdev_predictions) {

  G1Predictions predictor(0.5);

  TruncatedSeq s;

  s.add(0.5);

  double p1 = predictor.get_new_prediction(&s);

  ASSERT_GT(p1, s.davg()) << "First prediction must be greater than average";

  s.add(0.2);

  double p2 = predictor.get_new_prediction(&s);

  ASSERT_GT(p1, p2) << "First prediction must be greater than second";

  s.add(0.5);

  double p3 = predictor.get_new_prediction(&s);

  ASSERT_GT(p2, p3) << "Second prediction must be greater than third";

  s.add(0.2);

  s.add(2.0);

  double p4 = predictor.get_new_prediction(&s);

  ASSERT_GT(p4, p3) << "Fourth prediction must be greater than third";

}