test/hotspot/jtreg/serviceability/tmtools/jstat/utils/GeneratedClassProducer.java

/*
 * Copyright (c) 2015, 2018, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package utils;

import jdk.test.lib.classloader.GeneratingClassLoader;

/**
 * Garbage producer that creates classes loaded with GeneratingClassLoader.
 *
 * Note: this class is not thread-safe.
 */
class GeneratedClassProducer {

    private int number;
    private String className;
    private StringBuilder sb = new StringBuilder();
    private int minPerClassLoader = 50;
    private int maxPerClassLoader = 150;
    private int count;
    private GeneratingClassLoader loader = new GeneratingClassLoader();

    GeneratedClassProducer() {
        this(GeneratingClassLoader.DEFAULT_CLASSNAME);
    }

    GeneratedClassProducer(String className) {
        this.className = className;
    }

    String getNewName() {
        sb.delete(0, sb.length());
        sb.append("Class");
        sb.append(number);
        int n = loader.getNameLength() - sb.length();
        for (int i = 0; i < n; ++i) {
            sb.append('_');
        }
        return sb.toString();
    }

    Class create(long memory) {
        try {
            if (number++ > maxPerClassLoader || loader == null) {
                loader = new GeneratingClassLoader(className);
                count = 50;
                number = 0;
            }
            return loader.loadClass(getNewName());
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }
    }
}