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1 /*
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2 * Copyright 2003 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25
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26 // Contains two generations that both use an AdjoiningVirtualSpaces.
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27 // The two generations are adjacent in the reserved space for the
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28 // heap. Each generation has a virtual space and shrinking and
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29 // expanding of the generations can still be down with that
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30 // virtual space as was previously done. If expanding of reserved
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31 // size of a generation is required, the adjacent generation
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32 // must be shrunk. Adjusting the boundary between the generations
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33 // is called for in this class.
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34
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35 class AdjoiningGenerations : public CHeapObj {
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36 friend class VMStructs;
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37 private:
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38 // The young generation and old generation, respectively
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39 PSYoungGen* _young_gen;
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40 PSOldGen* _old_gen;
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41
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42 // The spaces used by the two generations.
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43 AdjoiningVirtualSpaces _virtual_spaces;
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44
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45 // Move boundary up to expand old gen. Checks are made to
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46 // determine if the move can be done with specified limits.
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47 void request_old_gen_expansion(size_t desired_change_in_bytes);
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48 // Move boundary down to expand young gen.
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49 bool request_young_gen_expansion(size_t desired_change_in_bytes);
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50
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51 public:
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52 AdjoiningGenerations(ReservedSpace rs,
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53 size_t init_low_byte_size,
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54 size_t min_low_byte_size,
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55 size_t max_low_byte_size,
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56 size_t init_high_byte_size,
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57 size_t min_high_byte_size,
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58 size_t max_high_bytes_size,
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59 size_t alignment);
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60
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61 // Accessors
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62 PSYoungGen* young_gen() { return _young_gen; }
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63 PSOldGen* old_gen() { return _old_gen; }
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64
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65 AdjoiningVirtualSpaces* virtual_spaces() { return &_virtual_spaces; }
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66
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67 // Additional space is needed in the old generation. Check
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68 // the available space and attempt to move the boundary if more space
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69 // is needed. The growth is not guaranteed to occur.
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70 void adjust_boundary_for_old_gen_needs(size_t desired_change_in_bytes);
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71 // Similary for a growth of the young generation.
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72 void adjust_boundary_for_young_gen_needs(size_t eden_size, size_t survivor_size);
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73
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74 // Return the total byte size of the reserved space
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75 // for the adjoining generations.
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76 size_t reserved_byte_size();
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77 };
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