1 /*
   2  * Copyright (c) 2013, 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_CLASSFILE_METADATAONSTACKMARK_HPP
  26 #define SHARE_VM_CLASSFILE_METADATAONSTACKMARK_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "utilities/chunkedList.hpp"
  30 
  31 class Metadata;
  32 
  33 typedef ChunkedList<Metadata*, mtInternal> MetadataOnStackBuffer;
  34 
  35 // Helper class to mark and unmark metadata used on the stack as either handles
  36 // or executing methods, so that it can't be deleted during class redefinition
  37 // and class unloading.
  38 // This is also used for other things that can be deallocated, like class
  39 // metadata during parsing, relocated methods, and methods in backtraces.
  40 class MetadataOnStackMark : public StackObj {
  41   NOT_PRODUCT(static bool _is_active;)
  42 
  43   static volatile MetadataOnStackBuffer* _used_buffers;
  44   static volatile MetadataOnStackBuffer* _free_buffers;
  45 
  46   static MetadataOnStackBuffer* allocate_buffer();
  47   static void retire_buffer(MetadataOnStackBuffer* buffer);
  48 
  49  public:
  50   MetadataOnStackMark(bool visit_code_cache);
  51    ~MetadataOnStackMark();
  52 
  53   static void record(Metadata* m, Thread* thread);
  54   static void retire_buffer_for_thread(Thread* thread);
  55   static bool has_buffer_for_thread(Thread* thread);
  56 };
  57 
  58 #endif // SHARE_VM_CLASSFILE_METADATAONSTACKMARK_HPP