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 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_PARALLEL_ADJOININGVIRTUALSPACES_HPP 26 #define SHARE_VM_GC_PARALLEL_ADJOININGVIRTUALSPACES_HPP 27 28 #include "gc/parallel/psVirtualspace.hpp" 29 30 31 // Contains two virtual spaces that each can individually span 32 // most of the reserved region but committed parts of which 33 // cannot overlap. 34 // 35 // +-------+ <--- high_boundary for H 36 // | | 37 // | H | 38 // | | 39 // | | 40 // | | 41 // --------- <--- low for H 42 // | | 43 // ========= <--- low_boundary for H, high_boundary for L 44 // | | 45 // | | 46 // | | 47 // --------- <--- high for L 48 // | | 49 // | L | 50 // | | 51 // | | 52 // | | 53 // +-------+ <--- low_boundary for L 54 // 55 // Each virtual space in the AdjoiningVirtualSpaces grows and shrink 56 // within its reserved region (between the low_boundary and the 57 // boundary) independently. If L want to grow above its high_boundary, 58 // then the high_boundary of L and the low_boundary of H must be 59 // moved up consistently. AdjoiningVirtualSpaces provide the 60 // interfaces for moving the this boundary. 61 62 class AdjoiningVirtualSpaces { 63 // space at the high end and the low end, respectively 64 PSVirtualSpace* _high; 65 PSVirtualSpace* _low; 66 67 // The reserved space spanned by the two spaces. 68 ReservedSpace _reserved_space; 69 70 // The minimum byte size for the low space. It will not 71 // be shrunk below this value. 72 size_t _min_low_byte_size; 73 // Same for the high space 74 size_t _min_high_byte_size; 75 76 const size_t _alignment; 77 78 public: 79 // Allocates two virtual spaces that will be located at the 80 // high and low ends. Does no initialization. 81 AdjoiningVirtualSpaces(ReservedSpace rs, 82 size_t min_low_byte_size, 83 size_t min_high_byte_size, 84 size_t alignment); 85 86 // accessors 87 PSVirtualSpace* high() { return _high; } 88 PSVirtualSpace* low() { return _low; } 89 ReservedSpace reserved_space() { return _reserved_space; } 90 size_t min_low_byte_size() { return _min_low_byte_size; } 91 size_t min_high_byte_size() { return _min_high_byte_size; } 92 size_t alignment() const { return _alignment; } 93 94 // move boundary between the two spaces up 95 bool adjust_boundary_up(size_t size_in_bytes); 96 // and down 97 bool adjust_boundary_down(size_t size_in_bytes); 98 99 // Maximum byte size for the high space. 100 size_t high_byte_size_limit() { 101 return _reserved_space.size() - _min_low_byte_size; 102 } 103 // Maximum byte size for the low space. 104 size_t low_byte_size_limit() { 105 return _reserved_space.size() - _min_high_byte_size; 106 } 107 108 // Sets the boundaries for the virtual spaces and commits and 109 // initial size; 110 void initialize(size_t max_low_byte_size, 111 size_t init_low_byte_size, 112 size_t init_high_byte_size); 113 }; 114 115 #endif // SHARE_VM_GC_PARALLEL_ADJOININGVIRTUALSPACES_HPP