1 /* 2 * Copyright (c) 2000, 2008, 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 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and 26 // enumerate ref fields that have been modified (since the last 27 // enumeration), using a card table. 28 29 class OopClosure; 30 class Generation; 31 32 class ModRefBarrierSet: public BarrierSet { 33 public: 34 35 ModRefBarrierSet() { _kind = BarrierSet::ModRef; } 36 37 bool is_a(BarrierSet::Name bsn) { 38 return bsn == BarrierSet::ModRef; 39 } 40 41 // Barriers only on ref writes. 42 bool has_read_ref_barrier() { return false; } 43 bool has_read_prim_barrier() { return false; } 44 bool has_write_ref_barrier() { return true; } 45 bool has_write_prim_barrier() { return false; } 46 47 bool read_ref_needs_barrier(void* field) { return false; } 48 bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; } 49 virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0; 50 bool write_prim_needs_barrier(HeapWord* field, size_t bytes, 51 juint val1, juint val2) { return false; } 52 53 void write_prim_field(oop obj, size_t offset, size_t bytes, 54 juint val1, juint val2) {} 55 56 void read_ref_field(void* field) {} 57 void read_prim_field(HeapWord* field, size_t bytes) {} 58 protected: 59 virtual void write_ref_field_work(void* field, oop new_val) = 0; 60 public: 61 void write_prim_field(HeapWord* field, size_t bytes, 62 juint val1, juint val2) {} 63 64 bool has_read_ref_array_opt() { return false; } 65 bool has_read_prim_array_opt() { return false; } 66 bool has_write_prim_array_opt() { return false; } 67 68 bool has_read_region_opt() { return false; } 69 70 71 // These operations should assert false unless the correponding operation 72 // above returns true. 73 void read_ref_array(MemRegion mr) { 74 assert(false, "can't call"); 75 } 76 void read_prim_array(MemRegion mr) { 77 assert(false, "can't call"); 78 } 79 void write_prim_array(MemRegion mr) { 80 assert(false, "can't call"); 81 } 82 void read_region(MemRegion mr) { 83 assert(false, "can't call"); 84 } 85 86 // Invoke "cl->do_oop" on (the address of) every possibly-modifed 87 // reference field in objects in "sp". If "clear" is "true", the oops 88 // are no longer considered possibly modified after application of the 89 // closure. If' "before_save_marks" is true, oops in objects allocated 90 // after the last call to "save_marks" on "sp" will not be considered. 91 virtual void mod_oop_in_space_iterate(Space* sp, OopClosure* cl, 92 bool clear = false, 93 bool before_save_marks = false) = 0; 94 95 // Causes all refs in "mr" to be assumed to be modified. If "whole_heap" 96 // is true, the caller asserts that the entire heap is being invalidated, 97 // which may admit an optimized implementation for some barriers. 98 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0; 99 100 // The caller guarantees that "mr" contains no references. (Perhaps it's 101 // objects have been moved elsewhere.) 102 virtual void clear(MemRegion mr) = 0; 103 104 // Pass along the argument to the superclass. 105 ModRefBarrierSet(int max_covered_regions) : 106 BarrierSet(max_covered_regions) {} 107 108 #ifndef PRODUCT 109 // Verifies that the given region contains no modified references. 110 virtual void verify_clean_region(MemRegion mr) = 0; 111 #endif 112 113 };