1 /*
   2  * Copyright (c) 2005, 2006, 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 // A Generation that does parallel young-gen collection extended
  26 // for adaptive size policy.
  27 
  28 // Division of generation into spaces
  29 // done by DefNewGeneration::compute_space_boundaries()
  30 //      +---------------+
  31 //      | uncommitted   |
  32 //      |---------------|
  33 //      | ss0           |
  34 //      |---------------|
  35 //      | ss1           |
  36 //      |---------------|
  37 //      |               |
  38 //      | eden          |
  39 //      |               |
  40 //      +---------------+       <-- low end of VirtualSpace
  41 //
  42 class ASParNewGeneration: public ParNewGeneration {
  43 
  44   size_t _min_gen_size;
  45 
  46   // Resize the generation based on the desired sizes of
  47   // the constituent spaces.
  48   bool resize_generation(size_t eden_size, size_t survivor_size);
  49   // Resize the spaces based on their desired sizes but
  50   // respecting the maximum size of the generation.
  51   void resize_spaces(size_t eden_size, size_t survivor_size);
  52   // Return the byte size remaining to the minimum generation size.
  53   size_t available_to_min_gen();
  54   // Return the byte size remaining to the live data in the generation.
  55   size_t available_to_live() const;
  56   // Return the byte size that the generation is allowed to shrink.
  57   size_t limit_gen_shrink(size_t bytes);
  58   // Reset the size of the spaces after a shrink of the generation.
  59   void reset_survivors_after_shrink();
  60 
  61   // Accessor
  62   VirtualSpace* virtual_space() { return &_virtual_space; }
  63 
  64   virtual void adjust_desired_tenuring_threshold();
  65 
  66  public:
  67 
  68   ASParNewGeneration(ReservedSpace rs,
  69                      size_t initial_byte_size,
  70                      size_t min_byte_size,
  71                      int level);
  72 
  73   virtual const char* short_name() const { return "ASParNew"; }
  74   virtual const char* name() const;
  75   virtual Generation::Name kind() { return ASParNew; }
  76 
  77   // Change the sizes of eden and the survivor spaces in
  78   // the generation.  The parameters are desired sizes
  79   // and are not guaranteed to be met.  For example, if
  80   // the total is larger than the generation.
  81   void resize(size_t eden_size, size_t survivor_size);
  82 
  83   virtual void compute_new_size();
  84 
  85   size_t max_gen_size()                 { return _reserved.byte_size(); }
  86   size_t min_gen_size() const           { return _min_gen_size; }
  87 
  88   // Space boundary invariant checker
  89   void space_invariants() PRODUCT_RETURN;
  90 };