1 /*

     2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_OOPS_OOPHANDLE_HPP

    26 #define SHARE_VM_OOPS_OOPHANDLE_HPP

    27 

    28 #include "oops/oop.hpp"

    29 #include "runtime/atomic.hpp"

    30 #include "runtime/orderAccess.hpp"

    31 

    32 // Simple class for encapsulating oop pointers stored in metadata.

    33 // These are different from Handle.  The Handle class stores pointers

    34 // to oops on the stack, and manages the allocation from a thread local

    35 // area in the constructor.

    36 // This assumes that the caller will allocate the handle in the appropriate

    37 // area.  The reason for the encapsulation is to help with naming and to allow

    38 // future uses for read barriers.

    39 

    40 class OopHandle {

    41 private:

    42   oop* _obj;

    43 

    44 public:

    45   OopHandle() : _obj(NULL) {}

    46   OopHandle(oop* w) : _obj(w) {}

    47 

    48   oop resolve() const { return (_obj == NULL) ? (oop)NULL : *_obj; }

    49 };

    50 

    51 #endif // SHARE_VM_OOPS_OOPHANDLE_HPP