1 /*
2 * Copyright (c) 2001, 2010, 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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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 class GenRemSet: public CHeapObj {
39 friend class Generation;
40
41 BarrierSet* _bs;
42
43 public:
44 enum Name {
45 CardTable,
46 Other
47 };
48
49 GenRemSet(BarrierSet * bs) : _bs(bs) {}
50 GenRemSet() : _bs(NULL) {}
51
52 virtual Name rs_kind() = 0;
53
54 // These are for dynamic downcasts. Unfortunately that it names the
55 // possible subtypes (but not that they are subtypes!) Return NULL if
56 // the cast is invalide.
57 virtual CardTableRS* as_CardTableRS() { return NULL; }
58
59 // Return the barrier set associated with "this."
60 BarrierSet* bs() { return _bs; }
61
62 // Set the barrier set.
63 void set_bs(BarrierSet* bs) { _bs = bs; }
64
65 // Do any (sequential) processing necessary to prepare for (possibly
66 // "parallel", if that arg is true) calls to younger_refs_iterate.
67 virtual void prepare_for_younger_refs_iterate(bool parallel) = 0;
68
69 // Apply the "do_oop" method of "blk" to (exactly) all oop locations
70 // 1) that are in objects allocated in "g" at the time of the last call
71 // to "save_Marks", and
72 // 2) that point to objects in younger generations.
73 virtual void younger_refs_iterate(Generation* g, OopsInGenClosure* blk) = 0;
74
75 virtual void younger_refs_in_space_iterate(Space* sp,
76 OopsInGenClosure* cl) = 0;
77
78 // This method is used to notify the remembered set that "new_val" has
79 // been written into "field" by the garbage collector.
80 void write_ref_field_gc(void* field, oop new_val);
81 protected:
82 virtual void write_ref_field_gc_work(void* field, oop new_val) = 0;
83 public:
84
85 // A version of the above suitable for use by parallel collectors.
86 virtual void write_ref_field_gc_par(void* field, oop new_val) = 0;
87
88 // Resize one of the regions covered by the remembered set.
89 virtual void resize_covered_region(MemRegion new_region) = 0;
90
91 // If the rem set imposes any alignment restrictions on boundaries
92 // within the heap, this function tells whether they are met.
93 virtual bool is_aligned(HeapWord* addr) = 0;
94
95 // If the RS (or BS) imposes an aligment constraint on maximum heap size.
96 // (This must be static, and dispatch on "nm", because it is called
97 // before an RS is created.)
98 static uintx max_alignment_constraint(Name nm);
99
100 virtual void verify() = 0;
101
102 // Verify that the remembered set has no entries for
103 // the heap interval denoted by mr. If there are any
104 // alignment constraints on the remembered set, only the
105 // part of the region that is aligned is checked.
106 //
107 // alignment boundaries
108 // +--------+-------+--------+-------+
109 // [ region mr )
110 // [ part checked )
111 virtual void verify_aligned_region_empty(MemRegion mr) = 0;
112
113 // If appropriate, print some information about the remset on "tty".
114 virtual void print() {}
115
116 // Informs the RS that the given memregion contains no references to
117 // younger generations.
118 virtual void clear(MemRegion mr) = 0;
119
120 // Informs the RS that there are no references to generations
121 // younger than gen from generations gen and older.
122 // The parameter clear_perm indicates if the perm_gen's
123 // remembered set should also be processed/cleared.
124 virtual void clear_into_younger(Generation* gen, bool clear_perm) = 0;
125
126 // Informs the RS that refs in the given "mr" may have changed
127 // arbitrarily, and therefore may contain old-to-young pointers.
128 // If "whole heap" is true, then this invalidation is part of an
129 // invalidation of the whole heap, which an implementation might
130 // handle differently than that of a sub-part of the heap.
131 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0;
132
133 // Informs the RS that refs in this generation
134 // may have changed arbitrarily, and therefore may contain
135 // old-to-young pointers in arbitrary locations. The parameter
136 // younger indicates if the same should be done for younger generations
137 // as well. The parameter perm indicates if the same should be done for
138 // perm gen as well.
139 virtual void invalidate_or_clear(Generation* gen, bool younger, bool perm) = 0;
140 };
141
142 #endif // SHARE_VM_MEMORY_GENREMSET_HPP