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1 /* |
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2 * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #ifndef SHARE_VM_GC_SHARED_SPACEDECORATOR_HPP |
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26 #define SHARE_VM_GC_SHARED_SPACEDECORATOR_HPP |
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27 |
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28 #include "gc/parallel/mutableSpace.hpp" |
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29 #include "gc/shared/space.hpp" |
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30 #include "utilities/globalDefinitions.hpp" |
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31 |
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32 class SpaceDecorator: public AllStatic { |
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33 public: |
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34 // Initialization flags. |
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35 static const bool Clear = true; |
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36 static const bool DontClear = false; |
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37 static const bool Mangle = true; |
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38 static const bool DontMangle = false; |
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39 }; |
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40 |
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41 // Functionality for use with class Space and class MutableSpace. |
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42 // The approach taken with the mangling is to mangle all |
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43 // the space initially and then to mangle areas that have |
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44 // been allocated since the last collection. Mangling is |
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45 // done in the context of a generation and in the context |
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46 // of a space. |
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47 // The space in a generation is mangled when it is first |
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48 // initialized and when the generation grows. The spaces |
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49 // are not necessarily up-to-date when this mangling occurs |
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50 // and the method mangle_region() is used. |
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51 // After allocations have been done in a space, the space generally |
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52 // need to be remangled. Remangling is only done on the |
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53 // recently allocated regions in the space. Typically, that is |
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54 // the region between the new top and the top just before a |
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55 // garbage collection. |
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56 // An exception to the usual mangling in a space is done when the |
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57 // space is used for an extraordinary purpose. Specifically, when |
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58 // to-space is used as scratch space for a mark-sweep-compact |
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59 // collection. |
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60 // Spaces are mangled after a collection. If the generation |
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61 // grows after a collection, the added space is mangled as part of |
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62 // the growth of the generation. No additional mangling is needed when the |
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63 // spaces are resized after an expansion. |
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64 // The class SpaceMangler keeps a pointer to the top of the allocated |
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65 // area and provides the methods for doing the piece meal mangling. |
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66 // Methods for doing sparces and full checking of the mangling are |
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67 // included. The full checking is done if DEBUG_MANGLING is defined. |
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68 // GenSpaceMangler is used with the GenCollectedHeap collectors and |
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69 // MutableSpaceMangler is used with the ParallelScavengeHeap collectors. |
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70 // These subclasses abstract the differences in the types of spaces used |
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71 // by each heap. |
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72 |
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73 class SpaceMangler: public CHeapObj<mtGC> { |
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74 friend class VMStructs; |
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75 |
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76 // High water mark for allocations. Typically, the space above |
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77 // this point have been mangle previously and don't need to be |
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78 // touched again. Space below this point has been allocated |
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79 // and remangling is needed between the current top and this |
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80 // high water mark. |
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81 HeapWord* _top_for_allocations; |
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82 HeapWord* top_for_allocations() { return _top_for_allocations; } |
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83 |
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84 public: |
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85 |
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86 // Setting _top_for_allocations to NULL at initialization |
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87 // makes it always below top so that mangling done as part |
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88 // of the initialize() call of a space does nothing (as it |
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89 // should since the mangling is done as part of the constructor |
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90 // for the space. |
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91 SpaceMangler() : _top_for_allocations(NULL) {} |
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92 |
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93 // Methods for top and end that delegate to the specific |
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94 // space type. |
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95 virtual HeapWord* top() const = 0; |
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96 virtual HeapWord* end() const = 0; |
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97 |
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98 // Return true if q matches the mangled pattern. |
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99 static bool is_mangled(HeapWord* q) PRODUCT_RETURN0; |
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100 |
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101 // Used to save the an address in a space for later use during mangling. |
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102 void set_top_for_allocations(HeapWord* v); |
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103 |
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104 // Overwrites the unused portion of this space. |
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105 // Mangle only the region not previously mangled [top, top_previously_mangled) |
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106 void mangle_unused_area(); |
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107 // Mangle all the unused region [top, end) |
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108 void mangle_unused_area_complete(); |
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109 // Do some sparse checking on the area that should have been mangled. |
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110 void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN; |
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111 // Do a complete check of the area that should be mangled. |
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112 void check_mangled_unused_area_complete() PRODUCT_RETURN; |
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113 |
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114 // Mangle the MemRegion. This is a non-space specific mangler. It |
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115 // is used during the initial mangling of a space before the space |
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116 // is fully constructed. Also is used when a generation is expanded |
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117 // and possibly before the spaces have been reshaped to to the new |
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118 // size of the generation. |
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119 static void mangle_region(MemRegion mr) PRODUCT_RETURN; |
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120 }; |
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121 |
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122 class ContiguousSpace; |
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123 |
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124 // For use with GenCollectedHeap's |
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125 class GenSpaceMangler: public SpaceMangler { |
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126 ContiguousSpace* _sp; |
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127 |
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128 ContiguousSpace* sp() { return _sp; } |
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129 |
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130 HeapWord* top() const { return _sp->top(); } |
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131 HeapWord* end() const { return _sp->end(); } |
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132 |
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133 public: |
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134 GenSpaceMangler(ContiguousSpace* sp) : SpaceMangler(), _sp(sp) {} |
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135 }; |
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136 |
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137 // For use with ParallelScavengeHeap's. |
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138 class MutableSpaceMangler: public SpaceMangler { |
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139 MutableSpace* _sp; |
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140 |
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141 MutableSpace* sp() { return _sp; } |
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142 |
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143 HeapWord* top() const { return _sp->top(); } |
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144 HeapWord* end() const { return _sp->end(); } |
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145 |
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146 public: |
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147 MutableSpaceMangler(MutableSpace* sp) : SpaceMangler(), _sp(sp) {} |
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148 }; |
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149 |
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150 #endif // SHARE_VM_GC_SHARED_SPACEDECORATOR_HPP |