/*
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 * 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.
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 */

/* @test 1.6 07/08/30
 * @bug 4076287
 * @summary Invoking get on a SoftReference shouldn't pin the referent
 * @run main/othervm -ms16m -mx16m Pin
 * @author Peter Jones
 * @author Mark Reinhold
 */


import java.lang.ref.SoftReference;

public class Pin {

    final static int NUM_BLOCKS = 128;
    final static int BLOCK_SIZE = 32768;

    public static void main(String[] args) throws Exception {

	SoftReference[] blocks = new SoftReference[NUM_BLOCKS];

	byte[] block;

	System.err.println("Filling array with " + NUM_BLOCKS +
			   " SoftReferences to blocks of " +
			   BLOCK_SIZE + " bytes.");

	for (int i = 0; i < NUM_BLOCKS; ++ i) {
	    block = new byte[BLOCK_SIZE];
	    SoftReference ref = new SoftReference(block);
	    blocks[i] = ref;
	}
	block = null;

	System.err.println("Allowing SoftReferences to be enqueued.");
	System.gc();
	Thread.sleep(1000);

        /* -- Commenting out the following section will hide the bug -- */
	System.err.println("Invoking get() on SoftReferences.");
	for (int i = 0; i < NUM_BLOCKS; ++ i) {
	    block = (byte[]) blocks[i].get();
	}
	block = null;
	/* -- end -- */

	System.err.println("Forcing desperate garbage collection...");
	java.util.Vector chain = new java.util.Vector();
	try {
	    while (true) {
		System.gc();
		int[] hungry = new int[65536];
		chain.addElement(hungry);
		Thread.sleep(100);		// yield, for what it's worth
	    }
	} catch (OutOfMemoryError e) {
	    System.err.println("Got OutOfMemoryError, as expected.");
	}

	int emptyCount = 0, fullCount = 0;
	System.err.print("Examining contents of array:");
	for (int i = 0; i < NUM_BLOCKS; ++ i) {
	    block = (byte[]) blocks[i].get();
	    if (block == null) {
		emptyCount++;
 	    } else {
		fullCount++;
	    }
	}
	System.err.println(" " + emptyCount + " empty, " +
			   fullCount + " full.");
	if (emptyCount == 0)
	    throw new Exception("No SoftReference instances were cleared");
    }

}