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From: cvs at opencores.org<cvs@o...>
Date: Mon Jan 28 16:49:33 CET 2008
Subject: [cvs-checkins] MODIFIED: jop ...
Date: 00/08/01 28:16:49

Added: jop/java/target/src/test/gctest GCTest11.java
Log:
A test to check if the GC is correctly collecting objects when

there are integers on the stack which are *not* actual references

(plain integers) but which may have, by chance,

the same values as actual handlers.




Revision Changes Path
1.1 jop/java/target/src/test/gctest/GCTest11.java

http://www.opencores.org/cvsweb.shtml/jop/java/target/src/test/gctest/GCTest11.java?rev=1.1&content-type=text/x-cvsweb-markup

Index: GCTest11.java
===================================================================
/*******************************************************************************

An implementation of the Java Debug Wire Protocol (JDWP) for JOP
Copyright (C) 2007 Paulo Abadie Guedes

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
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

*******************************************************************************/

package gctest;

import com.jopdesign.sys.*;

/**
* GCTest11.java
*
* A test to check if the GC is correctly collecting objects when
* there are integers on the stack which are *not* actual references
* (plain integers) but which may have, by chance,
* the same values as actual handlers.
*
* If this test fails, it shows it's necessary to use type information
* also for the stack. Otherwise it may cause floating garbage in some
* (maybe rare?) cases.
*
* This test is based on class GCTest9.
* Check also GC.push().
*
* @author Paulo Abadie Guedes
*
* 28/01/2008 - 12:03:02
*
*/
public class GCTest11
{
// this dummy value is necessary to make the object use
// some memory when created.
public int dummyValue;

public static void main(String s[])
{
// variables to hold memory levels during the test.
int free1, free2, free3, free4;
int i;

GC.gc();
System.out.println("GC");
System.out.print("Free memory 1: before -> ");
free1 = GC.freeMemory();
System.out.println(free1);

Object object = new GCTest11();

// get the object handle and assign it to an int.
// this is NOT a real object reference and should be ignored
// by the GC during garbage collection. It's just a plain int.
i = Native.toInt(object);

System.out.print("Object handle: ");
System.out.println(i);

// now GC should not recycle it.
GC.gc();

System.out.print("Free memory 2: object is still reachable -> ");
free2 = GC.freeMemory();
System.out.println(free2);
if(free1 <= free2)
{ System.out.println("FAIL. free memory 2 should be less than 1."); } // cut the reference here object = null; // now GC should recycle it! GC.gc(); System.out.print("Free memory 3: should be equals to free memory 1. ->"); free3 = GC.freeMemory(); System.out.println(free3); if(free3 != free1) { System.out.println("FAIL. the object should have been collected."); } // now if the following line makes GC collect the object, GC is wrong! i = 0; // GC should have recycle it already! GC.gc(); System.out.print("Free memory 4: "); free4 = GC.freeMemory(); System.out.println(free4); if(free3 != free4) { System.out.println("FAIL. Free memory in 3) and 4) should be the same."); } } }