1 /*
   2  * Copyright (c) 2003, 2015, 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
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  24 
  25 #ifndef SHARE_VM_GC_PARALLEL_ADJOININGGENERATIONS_HPP
  26 #define SHARE_VM_GC_PARALLEL_ADJOININGGENERATIONS_HPP
  27 
  28 #include "gc/parallel/adjoiningVirtualSpaces.hpp"
  29 #include "gc/parallel/asPSOldGen.hpp"
  30 #include "gc/parallel/asPSYoungGen.hpp"
  31 #include "gc/parallel/generationSizer.hpp"
  32 
  33 
  34 // Contains two generations that both use an AdjoiningVirtualSpaces.
  35 // The two generations are adjacent in the reserved space for the
  36 // heap.  Each generation has a virtual space and shrinking and
  37 // expanding of the generations can still be down with that
  38 // virtual space as was previously done.  If expanding of reserved
  39 // size of a generation is required, the adjacent generation
  40 // must be shrunk.  Adjusting the boundary between the generations
  41 // is called for in this class.
  42 
  43 class AdjoiningGenerations : public CHeapObj<mtGC> {
  44   friend class VMStructs;
  45  private:
  46   // The young generation and old generation, respectively
  47   PSYoungGen* _young_gen;
  48   PSOldGen* _old_gen;
  49 
  50   // The spaces used by the two generations.
  51   AdjoiningVirtualSpaces _virtual_spaces;
  52 
  53   // Move boundary up to expand old gen.  Checks are made to
  54   // determine if the move can be done with specified limits.
  55   void request_old_gen_expansion(size_t desired_change_in_bytes);
  56   // Move boundary down to expand young gen.
  57   bool request_young_gen_expansion(size_t desired_change_in_bytes);
  58 
  59  public:
  60   AdjoiningGenerations(ReservedSpace rs, GenerationSizer* policy, size_t alignment);
  61 
  62   // Accessors
  63   PSYoungGen* young_gen() { return _young_gen; }
  64   PSOldGen* old_gen() { return _old_gen; }
  65 
  66   AdjoiningVirtualSpaces* virtual_spaces() { return &_virtual_spaces; }
  67 
  68   // Additional space is needed in the old generation.  Check
  69   // the available space and attempt to move the boundary if more space
  70   // is needed.  The growth is not guaranteed to occur.
  71   void adjust_boundary_for_old_gen_needs(size_t desired_change_in_bytes);
  72   // Similarly for a growth of the young generation.
  73   void adjust_boundary_for_young_gen_needs(size_t eden_size, size_t survivor_size);
  74 
  75   // Return the total byte size of the reserved space
  76   // for the adjoining generations.
  77   size_t reserved_byte_size();
  78 };
  79 
  80 #endif // SHARE_VM_GC_PARALLEL_ADJOININGGENERATIONS_HPP