1 /* 2 * Copyright (c) 2003, 2018, 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 : public CHeapObj<mtGC> { 63 // space at the high end and the low end, respectively 64 PSVirtualSpace* _high; 65 PSVirtualSpace* _low; 66 67 protected: 68 // The reserved space spanned by the two spaces. 69 ReservedSpace _reserved_space; 70 71 // The minimum byte size for the low space. It will not 72 // be shrunk below this value. 73 size_t _min_low_byte_size; 74 // Same for the high space 75 size_t _min_high_byte_size; 76 77 const size_t _alignment; 78 79 public: 80 // Allocates two virtual spaces that will be located at the 81 // high and low ends. Does no initialization. 82 AdjoiningVirtualSpaces(ReservedSpace rs, 83 size_t min_low_byte_size, 84 size_t min_high_byte_size, 85 size_t alignment); 86 87 // accessors 88 virtual PSVirtualSpace* high() { return _high; } 89 virtual PSVirtualSpace* low() { return _low; } 90 ReservedSpace reserved_space() { return _reserved_space; } 91 size_t min_low_byte_size() { return _min_low_byte_size; } 92 size_t min_high_byte_size() { return _min_high_byte_size; } 93 size_t alignment() const { return _alignment; } 94 95 // move boundary between the two spaces up 96 virtual bool adjust_boundary_up(size_t size_in_bytes); 97 // and down 98 virtual bool adjust_boundary_down(size_t size_in_bytes); 99 100 // Maximum byte size for the high space. 101 size_t high_byte_size_limit() { 102 return _reserved_space.size() - _min_low_byte_size; 103 } 104 // Maximum byte size for the low space. 105 size_t low_byte_size_limit() { 106 return _reserved_space.size() - _min_high_byte_size; 107 } 108 109 // Sets the boundaries for the virtual spaces and commits and 110 // initial size; 111 void initialize(size_t max_low_byte_size, 112 size_t init_low_byte_size, 113 size_t init_high_byte_size); 114 }; 115 #endif // SHARE_VM_GC_PARALLEL_ADJOININGVIRTUALSPACES_HPP