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