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comparison src/share/vm/gc_implementation/shared/spaceDecorator.hpp @ 269:850fdf70db2b

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Merge
author jmasa
date Mon, 28 Jul 2008 15:30:23 -0700
parents 12eea04c8b06
children 9ee9cf798b59
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238:3df2fe7c4451 269:850fdf70db2b
1 /*
2 * Copyright 2002-2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 class SpaceDecorator: public AllStatic {
26 public:
27 // Initialization flags.
28 static const bool Clear = true;
29 static const bool DontClear = false;
30 static const bool Mangle = true;
31 static const bool DontMangle = false;
32 };
33
34 // Functionality for use with class Space and class MutableSpace.
35 // The approach taken with the mangling is to mangle all
36 // the space initially and then to mangle areas that have
37 // been allocated since the last collection. Mangling is
38 // done in the context of a generation and in the context
39 // of a space.
40 // The space in a generation is mangled when it is first
41 // initialized and when the generation grows. The spaces
42 // are not necessarily up-to-date when this mangling occurs
43 // and the method mangle_region() is used.
44 // After allocations have been done in a space, the space generally
45 // need to be remangled. Remangling is only done on the
46 // recently allocated regions in the space. Typically, that is
47 // the region between the new top and the top just before a
48 // garbage collection.
49 // An exception to the usual mangling in a space is done when the
50 // space is used for an extraordinary purpose. Specifically, when
51 // to-space is used as scratch space for a mark-sweep-compact
52 // collection.
53 // Spaces are mangled after a collection. If the generation
54 // grows after a collection, the added space is mangled as part of
55 // the growth of the generation. No additional mangling is needed when the
56 // spaces are resized after an expansion.
57 // The class SpaceMangler keeps a pointer to the top of the allocated
58 // area and provides the methods for doing the piece meal mangling.
59 // Methods for doing sparces and full checking of the mangling are
60 // included. The full checking is done if DEBUG_MANGLING is defined.
61 // GenSpaceMangler is used with the GenCollectedHeap collectors and
62 // MutableSpaceMangler is used with the ParallelScavengeHeap collectors.
63 // These subclasses abstract the differences in the types of spaces used
64 // by each heap.
65
66 class SpaceMangler: public CHeapObj {
67 friend class VMStructs;
68
69 // High water mark for allocations. Typically, the space above
70 // this point have been mangle previously and don't need to be
71 // touched again. Space belows this point has been allocated
72 // and remangling is needed between the current top and this
73 // high water mark.
74 HeapWord* _top_for_allocations;
75 HeapWord* top_for_allocations() { return _top_for_allocations; }
76
77 public:
78
79 // Setting _top_for_allocations to NULL at initialization
80 // makes it always below top so that mangling done as part
81 // of the initialize() call of a space does nothing (as it
82 // should since the mangling is done as part of the constructor
83 // for the space.
84 SpaceMangler() : _top_for_allocations(NULL) {}
85
86 // Methods for top and end that delegate to the specific
87 // space type.
88 virtual HeapWord* top() const = 0;
89 virtual HeapWord* end() const = 0;
90
91 // Return true if q matches the mangled pattern.
92 static bool is_mangled(HeapWord* q) PRODUCT_RETURN0;
93
94 // Used to save the an address in a space for later use during mangling.
95 void set_top_for_allocations(HeapWord* v);
96
97 // Overwrites the unused portion of this space.
98 // Mangle only the region not previously mangled [top, top_previously_mangled)
99 void mangle_unused_area();
100 // Mangle all the unused region [top, end)
101 void mangle_unused_area_complete();
102 // Do some sparse checking on the area that should have been mangled.
103 void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;
104 // Do a complete check of the area that should be mangled.
105 void check_mangled_unused_area_complete() PRODUCT_RETURN;
106
107 // Mangle the MemRegion. This is a non-space specific mangler. It
108 // is used during the initial mangling of a space before the space
109 // is fully constructed. Also is used when a generation is expanded
110 // and possibly before the spaces have been reshaped to to the new
111 // size of the generation.
112 static void mangle_region(MemRegion mr);
113 };
114
115 class ContiguousSpace;
116
117 // For use with GenCollectedHeap's
118 class GenSpaceMangler: public SpaceMangler {
119 ContiguousSpace* _sp;
120
121 ContiguousSpace* sp() { return _sp; }
122
123 HeapWord* top() const { return _sp->top(); }
124 HeapWord* end() const { return _sp->end(); }
125
126 public:
127 GenSpaceMangler(ContiguousSpace* sp) : SpaceMangler(), _sp(sp) {}
128 };
129
130 // For use with ParallelScavengeHeap's.
131 class MutableSpaceMangler: public SpaceMangler {
132 MutableSpace* _sp;
133
134 MutableSpace* sp() { return _sp; }
135
136 HeapWord* top() const { return _sp->top(); }
137 HeapWord* end() const { return _sp->end(); }
138
139 public:
140 MutableSpaceMangler(MutableSpace* sp) : SpaceMangler(), _sp(sp) {}
141 };