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 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
 * 
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * The contents of this file are subject to the terms of either the Universal Permissive License
 * v 1.0 as shown at http://oss.oracle.com/licenses/upl
 *
 * or the following license:
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions
 * and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 * 
 * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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 */
package scratch;

import java.util.HashSet;
import java.util.Random;

/**
 */
public class MemLeakExample {

	private static final int MAX_DATA_SIZE = 100000;

	private Random random;

	private String[] data;

	private HashSet<String> goodCache = new HashSet<>();
	private HashSet<String> badCache = new HashSet<>();

	public static void main(String args[]) {
		MemLeakExample mt = new MemLeakExample();
		mt.run();
	}

	private void run() {
		random = new Random(1234);

		for (int i = 0;; i++) {
			if (i % 8 == 0) {
				initData();
			}

			sleep(10);

			exerciseData();

			sleep(10);

			if (badCache.size() % 100 == 0) {
				System.out.println("badCache.size() = " + badCache.size());
			}
		}
	}

	private void initData() {
		int dataSize = random.nextInt(MAX_DATA_SIZE);
		data = new String[dataSize];
		for (int i = 0; i < dataSize; i++) {
			data[i] = i + "Foo Bar Baz Boooooooooooooo " + random.nextInt();
		}
	}

	private void exerciseData() {
		int dataToCache = data.length / 5;

		for (int i = 0; i < dataToCache; i++) {
			goodCache.add(data[i]);
			badCache.add(data[i]);
		}

		sleep(1);

		int lastIdx = dataToCache - 5;
		if (lastIdx < 0) {
			lastIdx = dataToCache;
		}
		for (int i = 0; i < lastIdx; i++) {
			badCache.remove(data[i]);
		}

		goodCache.clear();
	}

	private static void sleep(int ms) {
		try {
			Thread.sleep(ms);
		} catch (InterruptedException ex) {
		}
	}
}
