1 /*
   2  * Copyright (c) 2007, 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 class CardTableRS;   // fwd decl
  26 class ConcurrentMarkSweepGeneration;
  27 
  28 // A PermGen implemented with a CMS space, collected by a CMS collector.
  29 class CMSPermGen:  public PermGen {
  30   friend class VMStructs;
  31 
  32  protected:
  33   // The "generation" view.
  34   ConcurrentMarkSweepGeneration* _gen;
  35 
  36   // Override default implementation from PermGen
  37   virtual HeapWord* request_expand_and_allocate(Generation* gen, size_t size,
  38                                                 GCCause::Cause prev_cause);
  39 
  40  public:
  41   CMSPermGen(ReservedSpace rs, size_t initial_byte_size,
  42              CardTableRS* ct, FreeBlockDictionary::DictionaryChoice);
  43 
  44   HeapWord* mem_allocate(size_t size);
  45 
  46   void compute_new_size();
  47 
  48   Generation* as_gen() const { return _gen; }
  49 };
  50 
  51 // This is the "generation" view of a CMSPermGen.
  52 class CMSPermGenGen: public ConcurrentMarkSweepGeneration {
  53   // Abstractly, this is a subtype that gets access to protected fields.
  54   friend class CMSPermGen;
  55 public:
  56   CMSPermGenGen(ReservedSpace rs, size_t initial_byte_size,
  57                        int level, CardTableRS* ct):
  58     // See comments in the constructor for CompactibleFreeListSpace
  59     // regarding not using adaptive free lists for a perm gen.
  60     ConcurrentMarkSweepGeneration(rs, initial_byte_size, // MinPermHeapExapnsion
  61       level, ct, false /* use adaptive freelists */,
  62       (FreeBlockDictionary::DictionaryChoice)CMSDictionaryChoice)
  63   {}
  64 
  65   void initialize_performance_counters();
  66 
  67   const char* name() const {
  68     return "concurrent-mark-sweep perm gen";
  69   }
  70 
  71   const char* short_name() const {
  72     return "CMS Perm";
  73   }
  74 
  75   bool must_be_youngest() const { return false; }
  76   bool must_be_oldest() const { return false; }
  77 };