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/*
* Copyright (c) 2014, 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 gc.g1.unloading.keepref;
import gc.g1.unloading.check.cleanup.CleanupAction;
import gc.g1.unloading.loading.LibLoader;
/**
* This holder keeps reference through JNI local reference.
*/
public class JNILocalRefHolder implements RefHolder {
static {
//Force loading library
new LibLoader().hashCode();
}
// We use this field to transfer object into native JNI call. Idea is to avoid transferring link through method
// arguments.
private Object objectToKeep;
private native void holdWithJNILocalReference(Object syncObject);
@Override
public Object hold(Object object) {
objectToKeep = object;
final Object syncObject = new Object();
Thread keepingThread = new Thread(new Runnable() {
@Override
public void run() {
synchronized (syncObject) {
holdWithJNILocalReference(syncObject);
}
}
});
keepingThread.setDaemon(true);
keepingThread.start();
return new CleanupAction() {
@Override
public void cleanup() throws Exception {
synchronized (syncObject) {
syncObject.notify();
}
}
};
}
}
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