GCFakeStackUtil.java

/*
 * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Additionally licensed with:
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.spf4j.stackmonitor;

import javax.annotation.Nullable;

/**
 *
 * @author Zoltan Farkas
 */
public final class GCFakeStackUtil {

  private GCFakeStackUtil() { }

  private static final StackTraceElement[] GC_FAKE_STACK = new StackTraceElement[]{
    new StackTraceElement("java.lang.System", "gc", "System.java", -1)
  };

  @Nullable
  public static SampleNode createFakeGCSamples(final long prevGCTimeMillis, final long gcTimeMillis,
          final long stMs) {
    if (gcTimeMillis > prevGCTimeMillis) {
      int fakeSamples = (int) ((gcTimeMillis - prevGCTimeMillis) / stMs);
      if (fakeSamples > 0) {
        SampleNode node = SampleNode.createSampleNode(GC_FAKE_STACK);
        for (int i = 0; i < fakeSamples; i++) { // can be optimized
          SampleNode.addToSampleNode(node, GC_FAKE_STACK);
        }
        return node;
      } else {
        return null;
      }
    } else {
      return null;
    }
  }

}