1 /* 2 * Copyright (c) 2001, 2020, 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_GC_PARALLEL_PSYOUNGGEN_HPP 26 #define SHARE_GC_PARALLEL_PSYOUNGGEN_HPP 27 28 #include "gc/parallel/mutableSpace.hpp" 29 #include "gc/parallel/objectStartArray.hpp" 30 #include "gc/parallel/psGenerationCounters.hpp" 31 #include "gc/parallel/psVirtualspace.hpp" 32 #include "gc/parallel/spaceCounters.hpp" 33 34 class PSYoungGen : public CHeapObj<mtGC> { 35 friend class VMStructs; 36 friend class ParallelScavengeHeap; 37 friend class AdjoiningGenerations; 38 39 private: 40 MemRegion _reserved; 41 PSVirtualSpace* _virtual_space; 42 43 // Spaces 44 MutableSpace* _eden_space; 45 MutableSpace* _from_space; 46 MutableSpace* _to_space; 47 48 // Sizing information, in bytes, set in constructor 49 const size_t _init_gen_size; 50 const size_t _min_gen_size; 51 const size_t _max_gen_size; 52 53 // Performance counters 54 PSGenerationCounters* _gen_counters; 55 SpaceCounters* _eden_counters; 56 SpaceCounters* _from_counters; 57 SpaceCounters* _to_counters; 58 59 // Initialize the space boundaries 60 void compute_initial_space_boundaries(); 61 62 // Space boundary helper 63 void set_space_boundaries(size_t eden_size, size_t survivor_size); 64 65 bool resize_generation(size_t eden_size, size_t survivor_size); 66 void resize_spaces(size_t eden_size, size_t survivor_size); 67 68 // Adjust the spaces to be consistent with the virtual space. 69 void post_resize(); 70 71 // Given a desired shrinkage in the size of the young generation, 72 // return the actual size available for shrinkage. 73 size_t limit_gen_shrink(size_t desired_change); 74 // returns the number of bytes available from the current size 75 // down to the minimum generation size. 76 size_t available_to_min_gen(); 77 // Return the number of bytes available for shrinkage considering 78 // the location the live data in the generation. 79 size_t available_to_live(); 80 81 void initialize(ReservedSpace rs, size_t alignment); 82 void initialize_work(); 83 void initialize_virtual_space(ReservedSpace rs, size_t alignment); 84 85 public: 86 // Initialize the generation. 87 PSYoungGen(ReservedSpace rs, 88 size_t initial_byte_size, 89 size_t minimum_byte_size, 90 size_t maximum_byte_size); 91 92 MemRegion reserved() const { return _reserved; } 93 94 bool is_in(const void* p) const { 95 return _virtual_space->contains((void *)p); 96 } 97 98 bool is_in_reserved(const void* p) const { 99 return reserved().contains((void *)p); 100 } 101 102 MutableSpace* eden_space() const { return _eden_space; } 103 MutableSpace* from_space() const { return _from_space; } 104 MutableSpace* to_space() const { return _to_space; } 105 PSVirtualSpace* virtual_space() const { return _virtual_space; } 106 107 // Called during/after GC 108 void swap_spaces(); 109 110 // Resize generation using suggested free space size and survivor size 111 // NOTE: "eden_size" and "survivor_size" are suggestions only. Current 112 // heap layout (particularly, live objects in from space) might 113 // not allow us to use these values. 114 void resize(size_t eden_size, size_t survivor_size); 115 116 // Size info 117 size_t capacity_in_bytes() const; 118 size_t used_in_bytes() const; 119 size_t free_in_bytes() const; 120 121 size_t capacity_in_words() const; 122 size_t used_in_words() const; 123 size_t free_in_words() const; 124 125 size_t min_gen_size() const { return _min_gen_size; } 126 size_t max_gen_size() const { return _max_gen_size; } 127 128 bool is_maximal_no_gc() const { 129 return true; // Never expands except at a GC 130 } 131 132 // Allocation 133 HeapWord* allocate(size_t word_size) { 134 HeapWord* result = eden_space()->cas_allocate(word_size); 135 return result; 136 } 137 138 HeapWord* volatile* top_addr() const { return eden_space()->top_addr(); } 139 HeapWord** end_addr() const { return eden_space()->end_addr(); } 140 141 // Iteration. 142 void oop_iterate(OopIterateClosure* cl); 143 void object_iterate(ObjectClosure* cl); 144 145 void reset_survivors_after_shrink(); 146 147 // Performance Counter support 148 void update_counters(); 149 150 // Debugging - do not use for time critical operations 151 void print() const; 152 virtual void print_on(outputStream* st) const; 153 const char* name() const { return "PSYoungGen"; } 154 155 void verify(); 156 157 // Space boundary invariant checker 158 void space_invariants() PRODUCT_RETURN; 159 160 // Helper for mangling survivor spaces. 161 void mangle_survivors(MutableSpace* s1, 162 MemRegion s1MR, 163 MutableSpace* s2, 164 MemRegion s2MR) PRODUCT_RETURN; 165 166 void record_spaces_top() PRODUCT_RETURN; 167 }; 168 169 #endif // SHARE_GC_PARALLEL_PSYOUNGGEN_HPP