/*
 * Copyright (c) 2019, 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.
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 */

package sun.jvm.hotspot.oops;

import sun.jvm.hotspot.debugger.Address;
import sun.jvm.hotspot.debugger.OopHandle;
import sun.jvm.hotspot.runtime.VM;
import sun.jvm.hotspot.runtime.VMObject;
import sun.jvm.hotspot.types.AddressField;
import sun.jvm.hotspot.types.Type;
import sun.jvm.hotspot.types.TypeDataBase;

public class VMOopHandle extends VMObject {
    private static AddressField objField;

    static {
        VM.registerVMInitializedObserver((o, d) -> initialize(VM.getVM().getTypeDataBase()));
    }

    private static synchronized void initialize(TypeDataBase db) {
        Type type = db.lookupType("OopHandle");

        objField = type.getAddressField("_obj");
    }

    public VMOopHandle(Address addr) {
        super(addr);
    }

    public Address getObj() {
    	return objField.getValue(addr);
    }

    public Instance resolve() {
        Address handle = getObj();
        if (handle != null) {
          // Load through the handle
          OopHandle refs = VM.getVM().getUniverse().heap().oop_load_in_native(handle);
          return (Instance)VM.getVM().getObjectHeap().newOop(refs);
        }
        return null;
    }
}