1 /* 2 * Copyright (c) 2001, 2012, 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_MEMORY_GENREMSET_HPP 26 #define SHARE_VM_MEMORY_GENREMSET_HPP 27 28 #include "oops/oop.hpp" 29 30 // A GenRemSet provides ways of iterating over pointers accross generations. 31 // (This is especially useful for older-to-younger.) 32 33 class Generation; 34 class BarrierSet; 35 class OopsInGenClosure; 36 class CardTableRS; 37 38 // Helper to remember modified oops in all klasses. 39 class KlassRemSet { 40 bool _accumulate_modified_oops; 41 public: 42 KlassRemSet() : _accumulate_modified_oops(false) {} 43 void set_accumulate_modified_oops(bool value) { _accumulate_modified_oops = value; } 44 bool accumulate_modified_oops() { return _accumulate_modified_oops; } 45 bool mod_union_is_clear(); 46 void clear_mod_union(); 47 }; 48 49 class GenRemSet: public CHeapObj<mtGC> { 50 friend class Generation; 51 52 BarrierSet* _bs; 53 KlassRemSet _klass_rem_set; 54 55 public: 56 enum Name { 57 CardTable, 58 Other 59 }; 60 61 GenRemSet(BarrierSet * bs) : _bs(bs) {} 62 GenRemSet() : _bs(NULL) {} 63 64 virtual Name rs_kind() = 0; 65 66 // These are for dynamic downcasts. Unfortunately that it names the 67 // possible subtypes (but not that they are subtypes!) Return NULL if 68 // the cast is invalide. 69 virtual CardTableRS* as_CardTableRS() { return NULL; } 70 71 // Return the barrier set associated with "this." 72 BarrierSet* bs() { return _bs; } 73 74 // Set the barrier set. 75 void set_bs(BarrierSet* bs) { _bs = bs; } 76 77 KlassRemSet* klass_rem_set() { return &_klass_rem_set; } 78 79 // Do any (sequential) processing necessary to prepare for (possibly 80 // "parallel", if that arg is true) calls to younger_refs_iterate. 81 virtual void prepare_for_younger_refs_iterate(bool parallel) = 0; 82 83 // Apply the "do_oop" method of "blk" to (exactly) all oop locations 84 // 1) that are in objects allocated in "g" at the time of the last call 85 // to "save_Marks", and 86 // 2) that point to objects in younger generations. 87 virtual void younger_refs_iterate(Generation* g, OopsInGenClosure* blk) = 0; 88 89 virtual void younger_refs_in_space_iterate(Space* sp, 90 OopsInGenClosure* cl) = 0; 91 92 // This method is used to notify the remembered set that "new_val" has 93 // been written into "field" by the garbage collector. 94 void write_ref_field_gc(void* field, oop new_val); 95 protected: 96 virtual void write_ref_field_gc_work(void* field, oop new_val) = 0; 97 public: 98 99 // A version of the above suitable for use by parallel collectors. 100 virtual void write_ref_field_gc_par(void* field, oop new_val) = 0; 101 102 // Resize one of the regions covered by the remembered set. 103 virtual void resize_covered_region(MemRegion new_region) = 0; 104 105 // If the rem set imposes any alignment restrictions on boundaries 106 // within the heap, this function tells whether they are met. 107 virtual bool is_aligned(HeapWord* addr) = 0; 108 109 // If the RS (or BS) imposes an aligment constraint on maximum heap size. 110 // (This must be static, and dispatch on "nm", because it is called 111 // before an RS is created.) 112 static uintx max_alignment_constraint(Name nm); 113 114 virtual void verify() = 0; 115 116 // Verify that the remembered set has no entries for 117 // the heap interval denoted by mr. If there are any 118 // alignment constraints on the remembered set, only the 119 // part of the region that is aligned is checked. 120 // 121 // alignment boundaries 122 // +--------+-------+--------+-------+ 123 // [ region mr ) 124 // [ part checked ) 125 virtual void verify_aligned_region_empty(MemRegion mr) = 0; 126 127 // If appropriate, print some information about the remset on "tty". 128 virtual void print() {} 129 130 // Informs the RS that the given memregion contains no references to 131 // younger generations. 132 virtual void clear(MemRegion mr) = 0; 133 134 // Informs the RS that there are no references to generations 135 // younger than gen from generations gen and older. 136 // The parameter clear_perm indicates if the perm_gen's 137 // remembered set should also be processed/cleared. 138 virtual void clear_into_younger(Generation* old_gen) = 0; 139 140 // Informs the RS that refs in the given "mr" may have changed 141 // arbitrarily, and therefore may contain old-to-young pointers. 142 // If "whole heap" is true, then this invalidation is part of an 143 // invalidation of the whole heap, which an implementation might 144 // handle differently than that of a sub-part of the heap. 145 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0; 146 147 // Informs the RS that refs in this generation 148 // may have changed arbitrarily, and therefore may contain 149 // old-to-young pointers in arbitrary locations. 150 virtual void invalidate_or_clear(Generation* old_gen) = 0; 151 }; 152 153 #endif // SHARE_VM_MEMORY_GENREMSET_HPP