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