Mercurial > hg > truffle
comparison src/share/vm/gc_implementation/shared/spaceDecorator.hpp @ 263:12eea04c8b06
6672698: mangle_unused_area() should not remangle the entire heap at each collection.
Summary: Maintain a high water mark for the allocations in a space and mangle only up to that high water mark.
Reviewed-by: ysr, apetrusenko
author | jmasa |
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date | Wed, 09 Jul 2008 15:08:55 -0700 |
parents | |
children | 9ee9cf798b59 |
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225:286bee59f34b | 263:12eea04c8b06 |
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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 }; |