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_WEAKHANDLE_HPP
  26 #define SHARE_VM_OOPS_WEAKHANDLE_HPP
  27 
  28 #include "oops/oop.hpp"
  29 #include "runtime/handles.hpp"
  30 
  31 class outputStream;
  32 
  33 class WeakHandle {
  34 private:
  35   oop* _obj;
  36 
  37   WeakHandle(oop* w) : _obj(w) {}
  38 public:
  39   WeakHandle() : _obj(NULL) {} // needed for init
  40 
  41   static WeakHandle create(Handle obj);
  42   oop resolve() const;
  43   oop peek() const;
  44   void release() const;
  45   bool is_null() const { return _obj == NULL; }
  46 
  47   void print() const;
  48   void print_on(outputStream* st) const;
  49 };
  50 
  51 #endif // SHARE_VM_OOPS_WEAKHANDLE_HPP