annotate src/share/vm/memory/iterator.hpp @ 948:89e0543e1737

6884624: Update copyright year Summary: Update copyright for files that have been modified in 2009 through Septermber Reviewed-by: tbell, ohair
author xdono
date Tue, 22 Sep 2009 14:06:10 -0700
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1 /*
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2 * Copyright 1997-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // The following classes are C++ `closures` for iterating over objects, roots and spaces
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26
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27 class ReferenceProcessor;
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28 class DataLayout;
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29
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30 // Closure provides abortability.
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31
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32 class Closure : public StackObj {
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33 protected:
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34 bool _abort;
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35 void set_abort() { _abort = true; }
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36 public:
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37 Closure() : _abort(false) {}
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38 // A subtype can use this mechanism to indicate to some iterator mapping
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39 // functions that the iteration should cease.
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40 bool abort() { return _abort; }
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41 void clear_abort() { _abort = false; }
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42 };
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43
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44 // OopClosure is used for iterating through roots (oop*)
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45
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46 class OopClosure : public Closure {
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47 public:
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48 ReferenceProcessor* _ref_processor;
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49 OopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
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50 OopClosure() : _ref_processor(NULL) { }
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51 virtual void do_oop(oop* o) = 0;
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52 virtual void do_oop_v(oop* o) { do_oop(o); }
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53 virtual void do_oop(narrowOop* o) = 0;
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54 virtual void do_oop_v(narrowOop* o) { do_oop(o); }
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55
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56 // In support of post-processing of weak links of KlassKlass objects;
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57 // see KlassKlass::oop_oop_iterate().
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58
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59 virtual const bool should_remember_klasses() const {
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60 assert(!must_remember_klasses(), "Should have overriden this method.");
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61 return false;
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62 }
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63
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64 virtual void remember_klass(Klass* k) { /* do nothing */ }
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65
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66 // In support of post-processing of weak references in
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67 // ProfileData (MethodDataOop) objects; see, for example,
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68 // VirtualCallData::oop_iterate().
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69 virtual const bool should_remember_mdo() const { return false; }
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70 virtual void remember_mdo(DataLayout* v) { /* do nothing */ }
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71
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72 // If "true", invoke on nmethods (when scanning compiled frames).
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73 virtual const bool do_nmethods() const { return false; }
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74
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75 // The methods below control how object iterations invoking this closure
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76 // should be performed:
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77
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78 // If "true", invoke on header klass field.
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79 bool do_header() { return true; } // Note that this is non-virtual.
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80 // Controls how prefetching is done for invocations of this closure.
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81 Prefetch::style prefetch_style() { // Note that this is non-virtual.
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82 return Prefetch::do_none;
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83 }
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84
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85 // True iff this closure may be safely applied more than once to an oop
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86 // location without an intervening "major reset" (like the end of a GC).
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87 virtual bool idempotent() { return false; }
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88 virtual bool apply_to_weak_ref_discovered_field() { return false; }
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89
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90 #ifdef ASSERT
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91 static bool _must_remember_klasses;
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92 static bool must_remember_klasses();
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93 static void set_must_remember_klasses(bool v);
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94 #endif
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95 };
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96
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97 // ObjectClosure is used for iterating through an object space
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98
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99 class ObjectClosure : public Closure {
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100 public:
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101 // Called for each object.
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102 virtual void do_object(oop obj) = 0;
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103 };
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104
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105
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106 class BoolObjectClosure : public ObjectClosure {
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107 public:
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108 virtual bool do_object_b(oop obj) = 0;
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109 };
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110
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111 // Applies an oop closure to all ref fields in objects iterated over in an
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112 // object iteration.
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113 class ObjectToOopClosure: public ObjectClosure {
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114 OopClosure* _cl;
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115 public:
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116 void do_object(oop obj);
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117 ObjectToOopClosure(OopClosure* cl) : _cl(cl) {}
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118 };
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119
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120 // A version of ObjectClosure with "memory" (see _previous_address below)
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121 class UpwardsObjectClosure: public BoolObjectClosure {
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122 HeapWord* _previous_address;
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123 public:
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124 UpwardsObjectClosure() : _previous_address(NULL) { }
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125 void set_previous(HeapWord* addr) { _previous_address = addr; }
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126 HeapWord* previous() { return _previous_address; }
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127 // A return value of "true" can be used by the caller to decide
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128 // if this object's end should *NOT* be recorded in
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129 // _previous_address above.
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130 virtual bool do_object_bm(oop obj, MemRegion mr) = 0;
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131 };
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132
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133 // A version of ObjectClosure that is expected to be robust
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134 // in the face of possibly uninitialized objects.
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135 class ObjectClosureCareful : public ObjectClosure {
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136 public:
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137 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
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138 virtual size_t do_object_careful(oop p) = 0;
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139 };
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140
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141 // The following are used in CompactibleFreeListSpace and
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142 // ConcurrentMarkSweepGeneration.
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143
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144 // Blk closure (abstract class)
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145 class BlkClosure : public StackObj {
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146 public:
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147 virtual size_t do_blk(HeapWord* addr) = 0;
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148 };
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149
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150 // A version of BlkClosure that is expected to be robust
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151 // in the face of possibly uninitialized objects.
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152 class BlkClosureCareful : public BlkClosure {
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153 public:
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154 size_t do_blk(HeapWord* addr) {
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155 guarantee(false, "call do_blk_careful instead");
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156 return 0;
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157 }
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158 virtual size_t do_blk_careful(HeapWord* addr) = 0;
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159 };
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160
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161 // SpaceClosure is used for iterating over spaces
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162
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163 class Space;
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164 class CompactibleSpace;
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165
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166 class SpaceClosure : public StackObj {
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167 public:
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168 // Called for each space
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169 virtual void do_space(Space* s) = 0;
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170 };
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171
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172 class CompactibleSpaceClosure : public StackObj {
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173 public:
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174 // Called for each compactible space
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175 virtual void do_space(CompactibleSpace* s) = 0;
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176 };
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177
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178
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179
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180 // MonitorClosure is used for iterating over monitors in the monitors cache
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181
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182 class ObjectMonitor;
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183
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184 class MonitorClosure : public StackObj {
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185 public:
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186 // called for each monitor in cache
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187 virtual void do_monitor(ObjectMonitor* m) = 0;
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188 };
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189
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190 // A closure that is applied without any arguments.
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191 class VoidClosure : public StackObj {
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192 public:
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193 // I would have liked to declare this a pure virtual, but that breaks
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194 // in mysterious ways, for unknown reasons.
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195 virtual void do_void();
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196 };
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197
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198
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199 // YieldClosure is intended for use by iteration loops
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200 // to incrementalize their work, allowing interleaving
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201 // of an interruptable task so as to allow other
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202 // threads to run (which may not otherwise be able to access
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203 // exclusive resources, for instance). Additionally, the
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204 // closure also allows for aborting an ongoing iteration
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205 // by means of checking the return value from the polling
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206 // call.
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207 class YieldClosure : public StackObj {
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208 public:
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209 virtual bool should_return() = 0;
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210 };
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211
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212 // Abstract closure for serializing data (read or write).
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213
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214 class SerializeOopClosure : public OopClosure {
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215 public:
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216 // Return bool indicating whether closure implements read or write.
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217 virtual bool reading() const = 0;
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218
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219 // Read/write the int pointed to by i.
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220 virtual void do_int(int* i) = 0;
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221
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222 // Read/write the size_t pointed to by i.
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223 virtual void do_size_t(size_t* i) = 0;
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224
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225 // Read/write the void pointer pointed to by p.
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226 virtual void do_ptr(void** p) = 0;
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227
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228 // Read/write the HeapWord pointer pointed to be p.
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229 virtual void do_ptr(HeapWord** p) = 0;
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230
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231 // Read/write the region specified.
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232 virtual void do_region(u_char* start, size_t size) = 0;
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233
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234 // Check/write the tag. If reading, then compare the tag against
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235 // the passed in value and fail is they don't match. This allows
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236 // for verification that sections of the serialized data are of the
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237 // correct length.
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238 virtual void do_tag(int tag) = 0;
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239 };
935
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240
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241 #ifdef ASSERT
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242 // This class is used to flag phases of a collection that
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243 // can unload classes and which should override the
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244 // should_remember_klasses() and remember_klass() of OopClosure.
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245 // The _must_remember_klasses is set in the contructor and restored
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246 // in the destructor. _must_remember_klasses is checked in assertions
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247 // in the OopClosure implementations of should_remember_klasses() and
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248 // remember_klass() and the expectation is that the OopClosure
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249 // implementation should not be in use if _must_remember_klasses is set.
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250 // Instances of RememberKlassesChecker can be place in
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251 // marking phases of collections which can do class unloading.
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252 // RememberKlassesChecker can be passed "false" to turn off checking.
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253 // It is used by CMS when CMS yields to a different collector.
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254 class RememberKlassesChecker: StackObj {
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255 bool _state;
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256 bool _skip;
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257 public:
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258 RememberKlassesChecker(bool checking_on) : _state(false), _skip(false) {
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259 _skip = !(ClassUnloading && !UseConcMarkSweepGC ||
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260 CMSClassUnloadingEnabled && UseConcMarkSweepGC);
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261 if (_skip) {
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262 return;
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263 }
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264 _state = OopClosure::must_remember_klasses();
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265 OopClosure::set_must_remember_klasses(checking_on);
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266 }
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267 ~RememberKlassesChecker() {
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268 if (_skip) {
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269 return;
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270 }
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271 OopClosure::set_must_remember_klasses(_state);
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272 }
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273 };
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274 #endif // ASSERT