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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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 invalid.
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