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1 /* |
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2 * Copyright 1997-2007 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 // A Generation models a heap area for similarly-aged objects. |
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26 // It will contain one ore more spaces holding the actual objects. |
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27 // |
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28 // The Generation class hierarchy: |
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29 // |
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30 // Generation - abstract base class |
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31 // - DefNewGeneration - allocation area (copy collected) |
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32 // - ParNewGeneration - a DefNewGeneration that is collected by |
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33 // several threads |
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34 // - CardGeneration - abstract class adding offset array behavior |
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35 // - OneContigSpaceCardGeneration - abstract class holding a single |
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36 // contiguous space with card marking |
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37 // - TenuredGeneration - tenured (old object) space (markSweepCompact) |
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38 // - CompactingPermGenGen - reflective object area (klasses, methods, symbols, ...) |
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39 // - ConcurrentMarkSweepGeneration - Mostly Concurrent Mark Sweep Generation |
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40 // (Detlefs-Printezis refinement of |
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41 // Boehm-Demers-Schenker) |
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42 // |
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43 // The system configurations currently allowed are: |
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44 // |
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45 // DefNewGeneration + TenuredGeneration + PermGeneration |
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46 // DefNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen |
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47 // |
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48 // ParNewGeneration + TenuredGeneration + PermGeneration |
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49 // ParNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen |
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50 // |
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51 |
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52 class DefNewGeneration; |
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53 class GenerationSpec; |
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54 class CompactibleSpace; |
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55 class ContiguousSpace; |
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56 class CompactPoint; |
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57 class OopsInGenClosure; |
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58 class OopClosure; |
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59 class ScanClosure; |
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60 class FastScanClosure; |
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61 class GenCollectedHeap; |
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62 class GenRemSet; |
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63 class GCStats; |
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64 |
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65 // A "ScratchBlock" represents a block of memory in one generation usable by |
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66 // another. It represents "num_words" free words, starting at and including |
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67 // the address of "this". |
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68 struct ScratchBlock { |
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69 ScratchBlock* next; |
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70 size_t num_words; |
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71 HeapWord scratch_space[1]; // Actually, of size "num_words-2" (assuming |
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72 // first two fields are word-sized.) |
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73 }; |
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74 |
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75 |
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76 class Generation: public CHeapObj { |
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77 friend class VMStructs; |
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78 private: |
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79 jlong _time_of_last_gc; // time when last gc on this generation happened (ms) |
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80 MemRegion _prev_used_region; // for collectors that want to "remember" a value for |
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81 // used region at some specific point during collection. |
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82 |
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83 protected: |
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84 // Minimum and maximum addresses for memory reserved (not necessarily |
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85 // committed) for generation. |
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86 // Used by card marking code. Must not overlap with address ranges of |
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87 // other generations. |
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88 MemRegion _reserved; |
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89 |
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90 // Memory area reserved for generation |
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91 VirtualSpace _virtual_space; |
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92 |
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93 // Level in the generation hierarchy. |
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94 int _level; |
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95 |
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96 // ("Weak") Reference processing support |
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97 ReferenceProcessor* _ref_processor; |
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98 |
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99 // Performance Counters |
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100 CollectorCounters* _gc_counters; |
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101 |
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102 // Statistics for garbage collection |
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103 GCStats* _gc_stats; |
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104 |
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105 // Returns the next generation in the configuration, or else NULL if this |
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106 // is the highest generation. |
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107 Generation* next_gen() const; |
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108 |
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109 // Initialize the generation. |
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110 Generation(ReservedSpace rs, size_t initial_byte_size, int level); |
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111 |
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112 // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in |
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113 // "sp" that point into younger generations. |
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114 // The iteration is only over objects allocated at the start of the |
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115 // iterations; objects allocated as a result of applying the closure are |
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116 // not included. |
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117 void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl); |
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118 |
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119 public: |
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120 // The set of possible generation kinds. |
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121 enum Name { |
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122 ASParNew, |
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123 ASConcurrentMarkSweep, |
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124 DefNew, |
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125 ParNew, |
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126 MarkSweepCompact, |
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127 ConcurrentMarkSweep, |
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128 Other |
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129 }; |
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130 |
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131 enum SomePublicConstants { |
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132 // Generations are GenGrain-aligned and have size that are multiples of |
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133 // GenGrain. |
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134 LogOfGenGrain = 16, |
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135 GenGrain = 1 << LogOfGenGrain |
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136 }; |
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137 |
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138 // allocate and initialize ("weak") refs processing support |
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139 virtual void ref_processor_init(); |
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140 void set_ref_processor(ReferenceProcessor* rp) { |
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141 assert(_ref_processor == NULL, "clobbering existing _ref_processor"); |
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142 _ref_processor = rp; |
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143 } |
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144 |
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145 virtual Generation::Name kind() { return Generation::Other; } |
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146 GenerationSpec* spec(); |
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147 |
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148 // This properly belongs in the collector, but for now this |
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149 // will do. |
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150 virtual bool refs_discovery_is_atomic() const { return true; } |
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151 virtual bool refs_discovery_is_mt() const { return false; } |
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152 |
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153 // Space enquiries (results in bytes) |
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154 virtual size_t capacity() const = 0; // The maximum number of object bytes the |
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155 // generation can currently hold. |
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156 virtual size_t used() const = 0; // The number of used bytes in the gen. |
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157 virtual size_t free() const = 0; // The number of free bytes in the gen. |
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158 |
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159 // Support for java.lang.Runtime.maxMemory(); see CollectedHeap. |
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160 // Returns the total number of bytes available in a generation |
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161 // for the allocation of objects. |
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162 virtual size_t max_capacity() const; |
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163 |
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164 // If this is a young generation, the maximum number of bytes that can be |
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165 // allocated in this generation before a GC is triggered. |
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166 virtual size_t capacity_before_gc() const { return 0; } |
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167 |
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168 // The largest number of contiguous free bytes in the generation, |
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169 // including expansion (Assumes called at a safepoint.) |
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170 virtual size_t contiguous_available() const = 0; |
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171 // The largest number of contiguous free bytes in this or any higher generation. |
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172 virtual size_t max_contiguous_available() const; |
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173 |
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174 // Returns true if promotions of the specified amount can |
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175 // be attempted safely (without a vm failure). |
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176 // Promotion of the full amount is not guaranteed but |
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177 // can be attempted. |
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178 // younger_handles_promotion_failure |
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179 // is true if the younger generation handles a promotion |
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180 // failure. |
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181 virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes, |
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182 bool younger_handles_promotion_failure) const; |
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183 |
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184 // Return an estimate of the maximum allocation that could be performed |
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185 // in the generation without triggering any collection or expansion |
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186 // activity. It is "unsafe" because no locks are taken; the result |
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187 // should be treated as an approximation, not a guarantee, for use in |
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188 // heuristic resizing decisions. |
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189 virtual size_t unsafe_max_alloc_nogc() const = 0; |
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190 |
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191 // Returns true if this generation cannot be expanded further |
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192 // without a GC. Override as appropriate. |
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193 virtual bool is_maximal_no_gc() const { |
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194 return _virtual_space.uncommitted_size() == 0; |
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195 } |
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196 |
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197 MemRegion reserved() const { return _reserved; } |
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198 |
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199 // Returns a region guaranteed to contain all the objects in the |
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200 // generation. |
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201 virtual MemRegion used_region() const { return _reserved; } |
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202 |
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203 MemRegion prev_used_region() const { return _prev_used_region; } |
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204 virtual void save_used_region() { _prev_used_region = used_region(); } |
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205 |
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206 // Returns "TRUE" iff "p" points into an allocated object in the generation. |
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207 // For some kinds of generations, this may be an expensive operation. |
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208 // To avoid performance problems stemming from its inadvertent use in |
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209 // product jvm's, we restrict its use to assertion checking or |
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210 // verification only. |
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211 virtual bool is_in(const void* p) const; |
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212 |
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213 /* Returns "TRUE" iff "p" points into the reserved area of the generation. */ |
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214 bool is_in_reserved(const void* p) const { |
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215 return _reserved.contains(p); |
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216 } |
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217 |
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218 // Check that the generation kind is DefNewGeneration or a sub |
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219 // class of DefNewGeneration and return a DefNewGeneration* |
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220 DefNewGeneration* as_DefNewGeneration(); |
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221 |
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222 // If some space in the generation contains the given "addr", return a |
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223 // pointer to that space, else return "NULL". |
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224 virtual Space* space_containing(const void* addr) const; |
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225 |
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226 // Iteration - do not use for time critical operations |
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227 virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0; |
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228 |
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229 // Returns the first space, if any, in the generation that can participate |
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230 // in compaction, or else "NULL". |
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231 virtual CompactibleSpace* first_compaction_space() const = 0; |
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232 |
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233 // Returns "true" iff this generation should be used to allocate an |
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234 // object of the given size. Young generations might |
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235 // wish to exclude very large objects, for example, since, if allocated |
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236 // often, they would greatly increase the frequency of young-gen |
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237 // collection. |
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238 virtual bool should_allocate(size_t word_size, bool is_tlab) { |
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239 bool result = false; |
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240 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize); |
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241 if (!is_tlab || supports_tlab_allocation()) { |
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242 result = (word_size > 0) && (word_size < overflow_limit); |
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243 } |
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244 return result; |
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245 } |
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246 |
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247 // Allocate and returns a block of the requested size, or returns "NULL". |
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248 // Assumes the caller has done any necessary locking. |
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249 virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0; |
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250 |
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251 // Like "allocate", but performs any necessary locking internally. |
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252 virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0; |
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253 |
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254 // A 'younger' gen has reached an allocation limit, and uses this to notify |
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255 // the next older gen. The return value is a new limit, or NULL if none. The |
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256 // caller must do the necessary locking. |
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257 virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top, |
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258 size_t word_size) { |
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259 return NULL; |
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260 } |
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261 |
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262 // Some generation may offer a region for shared, contiguous allocation, |
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263 // via inlined code (by exporting the address of the top and end fields |
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264 // defining the extent of the contiguous allocation region.) |
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265 |
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266 // This function returns "true" iff the heap supports this kind of |
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267 // allocation. (More precisely, this means the style of allocation that |
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268 // increments *top_addr()" with a CAS.) (Default is "no".) |
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269 // A generation that supports this allocation style must use lock-free |
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270 // allocation for *all* allocation, since there are times when lock free |
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271 // allocation will be concurrent with plain "allocate" calls. |
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272 virtual bool supports_inline_contig_alloc() const { return false; } |
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273 |
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274 // These functions return the addresses of the fields that define the |
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275 // boundaries of the contiguous allocation area. (These fields should be |
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276 // physicall near to one another.) |
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277 virtual HeapWord** top_addr() const { return NULL; } |
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278 virtual HeapWord** end_addr() const { return NULL; } |
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279 |
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280 // Thread-local allocation buffers |
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281 virtual bool supports_tlab_allocation() const { return false; } |
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282 virtual size_t tlab_capacity() const { |
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283 guarantee(false, "Generation doesn't support thread local allocation buffers"); |
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284 return 0; |
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285 } |
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286 virtual size_t unsafe_max_tlab_alloc() const { |
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287 guarantee(false, "Generation doesn't support thread local allocation buffers"); |
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288 return 0; |
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289 } |
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290 |
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291 // "obj" is the address of an object in a younger generation. Allocate space |
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292 // for "obj" in the current (or some higher) generation, and copy "obj" into |
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293 // the newly allocated space, if possible, returning the result (or NULL if |
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294 // the allocation failed). |
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295 // |
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296 // The "obj_size" argument is just obj->size(), passed along so the caller can |
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297 // avoid repeating the virtual call to retrieve it. |
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298 // |
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299 // The "ref" argument, if non-NULL, is the address of some reference to "obj" |
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300 // (that is "*ref == obj"); some generations may use this information to, for |
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301 // example, influence placement decisions. |
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302 // |
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303 // The default implementation ignores "ref" and calls allocate(). |
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304 virtual oop promote(oop obj, size_t obj_size, oop* ref); |
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305 |
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306 // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote |
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307 // object "obj", whose original mark word was "m", and whose size is |
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308 // "word_sz". If possible, allocate space for "obj", copy obj into it |
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309 // (taking care to copy "m" into the mark word when done, since the mark |
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310 // word of "obj" may have been overwritten with a forwarding pointer, and |
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311 // also taking care to copy the klass pointer *last*. Returns the new |
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312 // object if successful, or else NULL. |
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313 virtual oop par_promote(int thread_num, |
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314 oop obj, markOop m, size_t word_sz); |
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315 |
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316 // Undo, if possible, the most recent par_promote_alloc allocation by |
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317 // "thread_num" ("obj", of "word_sz"). |
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318 virtual void par_promote_alloc_undo(int thread_num, |
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319 HeapWord* obj, size_t word_sz); |
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320 |
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321 // Informs the current generation that all par_promote_alloc's in the |
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322 // collection have been completed; any supporting data structures can be |
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323 // reset. Default is to do nothing. |
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324 virtual void par_promote_alloc_done(int thread_num) {} |
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325 |
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326 // Informs the current generation that all oop_since_save_marks_iterates |
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327 // performed by "thread_num" in the current collection, if any, have been |
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328 // completed; any supporting data structures can be reset. Default is to |
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329 // do nothing. |
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330 virtual void par_oop_since_save_marks_iterate_done(int thread_num) {} |
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331 |
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332 // This generation will collect all younger generations |
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333 // during a full collection. |
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334 virtual bool full_collects_younger_generations() const { return false; } |
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335 |
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336 // This generation does in-place marking, meaning that mark words |
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337 // are mutated during the marking phase and presumably reinitialized |
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338 // to a canonical value after the GC. This is currently used by the |
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339 // biased locking implementation to determine whether additional |
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340 // work is required during the GC prologue and epilogue. |
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341 virtual bool performs_in_place_marking() const { return true; } |
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342 |
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343 // Returns "true" iff collect() should subsequently be called on this |
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344 // this generation. See comment below. |
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345 // This is a generic implementation which can be overridden. |
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346 // |
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347 // Note: in the current (1.4) implementation, when genCollectedHeap's |
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348 // incremental_collection_will_fail flag is set, all allocations are |
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349 // slow path (the only fast-path place to allocate is DefNew, which |
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350 // will be full if the flag is set). |
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351 // Thus, older generations which collect younger generations should |
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352 // test this flag and collect if it is set. |
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353 virtual bool should_collect(bool full, |
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354 size_t word_size, |
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355 bool is_tlab) { |
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356 return (full || should_allocate(word_size, is_tlab)); |
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357 } |
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358 |
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359 // Perform a garbage collection. |
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360 // If full is true attempt a full garbage collection of this generation. |
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361 // Otherwise, attempting to (at least) free enough space to support an |
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362 // allocation of the given "word_size". |
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363 virtual void collect(bool full, |
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364 bool clear_all_soft_refs, |
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365 size_t word_size, |
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366 bool is_tlab) = 0; |
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367 |
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368 // Perform a heap collection, attempting to create (at least) enough |
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369 // space to support an allocation of the given "word_size". If |
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370 // successful, perform the allocation and return the resulting |
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371 // "oop" (initializing the allocated block). If the allocation is |
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372 // still unsuccessful, return "NULL". |
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373 virtual HeapWord* expand_and_allocate(size_t word_size, |
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374 bool is_tlab, |
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375 bool parallel = false) = 0; |
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376 |
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377 // Some generations may require some cleanup or preparation actions before |
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378 // allowing a collection. The default is to do nothing. |
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379 virtual void gc_prologue(bool full) {}; |
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380 |
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381 // Some generations may require some cleanup actions after a collection. |
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382 // The default is to do nothing. |
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383 virtual void gc_epilogue(bool full) {}; |
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384 |
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385 // Some generations may need to be "fixed-up" after some allocation |
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386 // activity to make them parsable again. The default is to do nothing. |
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387 virtual void ensure_parsability() {}; |
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388 |
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389 // Time (in ms) when we were last collected or now if a collection is |
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390 // in progress. |
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391 virtual jlong time_of_last_gc(jlong now) { |
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392 // XXX See note in genCollectedHeap::millis_since_last_gc() |
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393 NOT_PRODUCT( |
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394 if (now < _time_of_last_gc) { |
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395 warning("time warp: %d to %d", _time_of_last_gc, now); |
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396 } |
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397 ) |
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398 return _time_of_last_gc; |
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399 } |
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400 |
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401 virtual void update_time_of_last_gc(jlong now) { |
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402 _time_of_last_gc = now; |
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403 } |
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404 |
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405 // Generations may keep statistics about collection. This |
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406 // method updates those statistics. current_level is |
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407 // the level of the collection that has most recently |
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408 // occurred. This allows the generation to decide what |
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409 // statistics are valid to collect. For example, the |
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410 // generation can decide to gather the amount of promoted data |
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411 // if the collection of the younger generations has completed. |
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412 GCStats* gc_stats() const { return _gc_stats; } |
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413 virtual void update_gc_stats(int current_level, bool full) {} |
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414 |
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415 // Mark sweep support phase2 |
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416 virtual void prepare_for_compaction(CompactPoint* cp); |
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417 // Mark sweep support phase3 |
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418 virtual void pre_adjust_pointers() {ShouldNotReachHere();} |
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419 virtual void adjust_pointers(); |
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420 // Mark sweep support phase4 |
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421 virtual void compact(); |
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422 virtual void post_compact() {ShouldNotReachHere();} |
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423 |
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424 // Support for CMS's rescan. In this general form we return a pointer |
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425 // to an abstract object that can be used, based on specific previously |
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426 // decided protocols, to exchange information between generations, |
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427 // information that may be useful for speeding up certain types of |
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428 // garbage collectors. A NULL value indicates to the client that |
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429 // no data recording is expected by the provider. The data-recorder is |
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430 // expected to be GC worker thread-local, with the worker index |
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431 // indicated by "thr_num". |
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432 virtual void* get_data_recorder(int thr_num) { return NULL; } |
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433 |
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434 // Some generations may require some cleanup actions before allowing |
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435 // a verification. |
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436 virtual void prepare_for_verify() {}; |
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437 |
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438 // Accessing "marks". |
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439 |
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440 // This function gives a generation a chance to note a point between |
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441 // collections. For example, a contiguous generation might note the |
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442 // beginning allocation point post-collection, which might allow some later |
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443 // operations to be optimized. |
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444 virtual void save_marks() {} |
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445 |
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446 // This function allows generations to initialize any "saved marks". That |
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447 // is, should only be called when the generation is empty. |
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448 virtual void reset_saved_marks() {} |
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449 |
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450 // This function is "true" iff any no allocations have occurred in the |
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451 // generation since the last call to "save_marks". |
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452 virtual bool no_allocs_since_save_marks() = 0; |
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453 |
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454 // Apply "cl->apply" to (the addresses of) all reference fields in objects |
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455 // allocated in the current generation since the last call to "save_marks". |
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456 // If more objects are allocated in this generation as a result of applying |
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457 // the closure, iterates over reference fields in those objects as well. |
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458 // Calls "save_marks" at the end of the iteration. |
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459 // General signature... |
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460 virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0; |
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461 // ...and specializations for de-virtualization. (The general |
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462 // implemention of the _nv versions call the virtual version. |
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463 // Note that the _nv suffix is not really semantically necessary, |
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464 // but it avoids some not-so-useful warnings on Solaris.) |
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465 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ |
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466 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ |
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467 oop_since_save_marks_iterate_v((OopsInGenClosure*)cl); \ |
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468 } |
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469 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL) |
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470 |
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471 #undef Generation_SINCE_SAVE_MARKS_DECL |
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472 |
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473 // The "requestor" generation is performing some garbage collection |
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474 // action for which it would be useful to have scratch space. If |
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475 // the target is not the requestor, no gc actions will be required |
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476 // of the target. The requestor promises to allocate no more than |
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477 // "max_alloc_words" in the target generation (via promotion say, |
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478 // if the requestor is a young generation and the target is older). |
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479 // If the target generation can provide any scratch space, it adds |
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480 // it to "list", leaving "list" pointing to the head of the |
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481 // augmented list. The default is to offer no space. |
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482 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, |
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483 size_t max_alloc_words) {} |
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484 |
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485 // When an older generation has been collected, and perhaps resized, |
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486 // this method will be invoked on all younger generations (from older to |
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487 // younger), allowing them to resize themselves as appropriate. |
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488 virtual void compute_new_size() = 0; |
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489 |
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490 // Printing |
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491 virtual const char* name() const = 0; |
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492 virtual const char* short_name() const = 0; |
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493 |
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494 int level() const { return _level; } |
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495 |
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496 // Attributes |
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497 |
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498 // True iff the given generation may only be the youngest generation. |
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499 virtual bool must_be_youngest() const = 0; |
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500 // True iff the given generation may only be the oldest generation. |
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501 virtual bool must_be_oldest() const = 0; |
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502 |
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503 // Reference Processing accessor |
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504 ReferenceProcessor* const ref_processor() { return _ref_processor; } |
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505 |
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506 // Iteration. |
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507 |
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508 // Iterate over all the ref-containing fields of all objects in the |
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509 // generation, calling "cl.do_oop" on each. |
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510 virtual void oop_iterate(OopClosure* cl); |
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511 |
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512 // Same as above, restricted to the intersection of a memory region and |
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513 // the generation. |
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514 virtual void oop_iterate(MemRegion mr, OopClosure* cl); |
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515 |
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516 // Iterate over all objects in the generation, calling "cl.do_object" on |
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517 // each. |
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518 virtual void object_iterate(ObjectClosure* cl); |
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519 |
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520 // Iterate over all objects allocated in the generation since the last |
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521 // collection, calling "cl.do_object" on each. The generation must have |
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522 // been initialized properly to support this function, or else this call |
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523 // will fail. |
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524 virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0; |
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525 |
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526 // Apply "cl->do_oop" to (the address of) all and only all the ref fields |
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527 // in the current generation that contain pointers to objects in younger |
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528 // generations. Objects allocated since the last "save_marks" call are |
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529 // excluded. |
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530 virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0; |
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531 |
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532 // Inform a generation that it longer contains references to objects |
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533 // in any younger generation. [e.g. Because younger gens are empty, |
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534 // clear the card table.] |
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535 virtual void clear_remembered_set() { } |
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536 |
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537 // Inform a generation that some of its objects have moved. [e.g. The |
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538 // generation's spaces were compacted, invalidating the card table.] |
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539 virtual void invalidate_remembered_set() { } |
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540 |
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541 // Block abstraction. |
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542 |
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543 // Returns the address of the start of the "block" that contains the |
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544 // address "addr". We say "blocks" instead of "object" since some heaps |
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545 // may not pack objects densely; a chunk may either be an object or a |
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546 // non-object. |
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547 virtual HeapWord* block_start(const void* addr) const; |
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548 |
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549 // Requires "addr" to be the start of a chunk, and returns its size. |
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550 // "addr + size" is required to be the start of a new chunk, or the end |
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551 // of the active area of the heap. |
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552 virtual size_t block_size(const HeapWord* addr) const ; |
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553 |
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554 // Requires "addr" to be the start of a block, and returns "TRUE" iff |
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555 // the block is an object. |
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556 virtual bool block_is_obj(const HeapWord* addr) const; |
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557 |
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558 |
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559 // PrintGC, PrintGCDetails support |
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560 void print_heap_change(size_t prev_used) const; |
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561 |
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562 // PrintHeapAtGC support |
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563 virtual void print() const; |
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564 virtual void print_on(outputStream* st) const; |
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565 |
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566 virtual void verify(bool allow_dirty) = 0; |
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567 |
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568 struct StatRecord { |
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569 int invocations; |
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570 elapsedTimer accumulated_time; |
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571 StatRecord() : |
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572 invocations(0), |
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573 accumulated_time(elapsedTimer()) {} |
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574 }; |
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575 private: |
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576 StatRecord _stat_record; |
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577 public: |
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578 StatRecord* stat_record() { return &_stat_record; } |
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579 |
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580 virtual void print_summary_info(); |
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581 virtual void print_summary_info_on(outputStream* st); |
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582 |
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583 // Performance Counter support |
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584 virtual void update_counters() = 0; |
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585 virtual CollectorCounters* counters() { return _gc_counters; } |
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586 }; |
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587 |
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588 // Class CardGeneration is a generation that is covered by a card table, |
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589 // and uses a card-size block-offset array to implement block_start. |
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590 |
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591 // class BlockOffsetArray; |
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592 // class BlockOffsetArrayContigSpace; |
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593 class BlockOffsetSharedArray; |
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594 |
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595 class CardGeneration: public Generation { |
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596 friend class VMStructs; |
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597 protected: |
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598 // This is shared with other generations. |
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599 GenRemSet* _rs; |
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600 // This is local to this generation. |
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601 BlockOffsetSharedArray* _bts; |
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602 |
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603 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level, |
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604 GenRemSet* remset); |
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605 |
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606 public: |
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607 |
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608 virtual void clear_remembered_set(); |
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609 |
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610 virtual void invalidate_remembered_set(); |
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611 |
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612 virtual void prepare_for_verify(); |
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613 }; |
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614 |
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615 // OneContigSpaceCardGeneration models a heap of old objects contained in a single |
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616 // contiguous space. |
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617 // |
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618 // Garbage collection is performed using mark-compact. |
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619 |
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620 class OneContigSpaceCardGeneration: public CardGeneration { |
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621 friend class VMStructs; |
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622 // Abstractly, this is a subtype that gets access to protected fields. |
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623 friend class CompactingPermGen; |
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624 friend class VM_PopulateDumpSharedSpace; |
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625 |
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626 protected: |
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627 size_t _min_heap_delta_bytes; // Minimum amount to expand. |
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628 ContiguousSpace* _the_space; // actual space holding objects |
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629 WaterMark _last_gc; // watermark between objects allocated before |
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630 // and after last GC. |
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631 |
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632 // Grow generation with specified size (returns false if unable to grow) |
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633 bool grow_by(size_t bytes); |
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634 // Grow generation to reserved size. |
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635 bool grow_to_reserved(); |
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636 // Shrink generation with specified size (returns false if unable to shrink) |
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637 void shrink_by(size_t bytes); |
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638 |
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639 // Allocation failure |
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640 void expand(size_t bytes, size_t expand_bytes); |
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641 void shrink(size_t bytes); |
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642 |
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643 // Accessing spaces |
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644 ContiguousSpace* the_space() const { return _the_space; } |
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645 |
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646 public: |
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647 OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size, |
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648 size_t min_heap_delta_bytes, |
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649 int level, GenRemSet* remset, |
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650 ContiguousSpace* space) : |
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651 CardGeneration(rs, initial_byte_size, level, remset), |
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652 _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes) |
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653 {} |
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654 |
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655 inline bool is_in(const void* p) const; |
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656 |
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657 // Space enquiries |
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658 size_t capacity() const; |
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659 size_t used() const; |
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660 size_t free() const; |
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661 |
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662 MemRegion used_region() const; |
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663 |
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664 size_t unsafe_max_alloc_nogc() const; |
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665 size_t contiguous_available() const; |
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666 |
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667 // Iteration |
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668 void object_iterate(ObjectClosure* blk); |
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669 void space_iterate(SpaceClosure* blk, bool usedOnly = false); |
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670 void object_iterate_since_last_GC(ObjectClosure* cl); |
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671 |
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672 void younger_refs_iterate(OopsInGenClosure* blk); |
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673 |
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674 inline CompactibleSpace* first_compaction_space() const; |
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675 |
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676 virtual inline HeapWord* allocate(size_t word_size, bool is_tlab); |
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677 virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab); |
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678 |
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679 // Accessing marks |
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680 inline WaterMark top_mark(); |
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681 inline WaterMark bottom_mark(); |
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682 |
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683 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ |
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684 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); |
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685 OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v) |
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686 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL) |
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687 |
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688 void save_marks(); |
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689 void reset_saved_marks(); |
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690 bool no_allocs_since_save_marks(); |
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691 |
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692 inline size_t block_size(const HeapWord* addr) const; |
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693 |
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694 inline bool block_is_obj(const HeapWord* addr) const; |
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695 |
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696 virtual void collect(bool full, |
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697 bool clear_all_soft_refs, |
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698 size_t size, |
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699 bool is_tlab); |
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700 HeapWord* expand_and_allocate(size_t size, |
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701 bool is_tlab, |
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702 bool parallel = false); |
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703 |
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704 virtual void prepare_for_verify(); |
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705 |
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706 virtual void gc_epilogue(bool full); |
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707 |
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708 virtual void verify(bool allow_dirty); |
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709 virtual void print_on(outputStream* st) const; |
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710 }; |