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1 /*
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2 * Copyright 2001-2007 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 G1RemSet provides ways of iterating over pointers into a selected
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26 // collection set.
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27
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28 class G1CollectedHeap;
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29 class CardTableModRefBarrierSet;
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30 class HRInto_G1RemSet;
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31 class ConcurrentG1Refine;
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32
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33 class G1RemSet {
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34 protected:
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35 G1CollectedHeap* _g1;
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36
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37 unsigned _conc_refine_traversals;
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38 unsigned _conc_refine_cards;
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39
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40 size_t n_workers();
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41
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42 public:
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43 G1RemSet(G1CollectedHeap* g1) :
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44 _g1(g1), _conc_refine_traversals(0), _conc_refine_cards(0)
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45 {}
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46
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47 // Invoke "blk->do_oop" on all pointers into the CS in object in regions
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48 // outside the CS (having invoked "blk->set_region" to set the "from"
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49 // region correctly beforehand.) The "worker_i" param is for the
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50 // parallel case where the number of the worker thread calling this
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51 // function can be helpful in partitioning the work to be done. It
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52 // should be the same as the "i" passed to the calling thread's
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53 // work(i) function. In the sequential case this param will be ingored.
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54 virtual void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
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55 int worker_i) = 0;
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56
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57 // Prepare for and cleanup after an oops_into_collection_set_do
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58 // call. Must call each of these once before and after (in sequential
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59 // code) any threads call oops into collection set do. (This offers an
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60 // opportunity to sequential setup and teardown of structures needed by a
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61 // parallel iteration over the CS's RS.)
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62 virtual void prepare_for_oops_into_collection_set_do() = 0;
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63 virtual void cleanup_after_oops_into_collection_set_do() = 0;
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64
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65 // If "this" is of the given subtype, return "this", else "NULL".
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66 virtual HRInto_G1RemSet* as_HRInto_G1RemSet() { return NULL; }
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67
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68 // Record, if necessary, the fact that *p (where "p" is in region "from")
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69 // has changed to its new value.
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70 virtual void write_ref(HeapRegion* from, oop* p) = 0;
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71 virtual void par_write_ref(HeapRegion* from, oop* p, int tid) = 0;
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72
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73 // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
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74 // or card, respectively, such that a region or card with a corresponding
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75 // 0 bit contains no part of any live object. Eliminates any remembered
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76 // set entries that correspond to dead heap ranges.
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77 virtual void scrub(BitMap* region_bm, BitMap* card_bm) = 0;
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78 // Like the above, but assumes is called in parallel: "worker_num" is the
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79 // parallel thread id of the current thread, and "claim_val" is the
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80 // value that should be used to claim heap regions.
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81 virtual void scrub_par(BitMap* region_bm, BitMap* card_bm,
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82 int worker_num, int claim_val) = 0;
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83
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84 // Do any "refinement" activity that might be appropriate to the given
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85 // G1RemSet. If "refinement" has iterateive "passes", do one pass.
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86 // If "t" is non-NULL, it is the thread performing the refinement.
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87 // Default implementation does nothing.
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88 virtual void concurrentRefinementPass(ConcurrentG1Refine* cg1r) {}
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89
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90 // Refine the card corresponding to "card_ptr". If "sts" is non-NULL,
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91 // join and leave around parts that must be atomic wrt GC. (NULL means
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92 // being done at a safepoint.)
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93 virtual void concurrentRefineOneCard(jbyte* card_ptr, int worker_i) {}
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94
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95 unsigned conc_refine_cards() { return _conc_refine_cards; }
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96
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97 // Print any relevant summary info.
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98 virtual void print_summary_info() {}
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99
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100 // Prepare remebered set for verification.
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101 virtual void prepare_for_verify() {};
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102 };
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103
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104
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105 // The simplest possible G1RemSet: iterates over all objects in non-CS
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106 // regions, searching for pointers into the CS.
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107 class StupidG1RemSet: public G1RemSet {
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108 public:
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109 StupidG1RemSet(G1CollectedHeap* g1) : G1RemSet(g1) {}
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110
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111 void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
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112 int worker_i);
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113
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114 void prepare_for_oops_into_collection_set_do() {}
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115 void cleanup_after_oops_into_collection_set_do() {}
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116
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117 // Nothing is necessary in the version below.
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118 void write_ref(HeapRegion* from, oop* p) {}
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119 void par_write_ref(HeapRegion* from, oop* p, int tid) {}
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120
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121 void scrub(BitMap* region_bm, BitMap* card_bm) {}
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122 void scrub_par(BitMap* region_bm, BitMap* card_bm,
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123 int worker_num, int claim_val) {}
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124
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125 };
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126
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127 // A G1RemSet in which each heap region has a rem set that records the
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128 // external heap references into it. Uses a mod ref bs to track updates,
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129 // so that they can be used to update the individual region remsets.
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130
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131 class HRInto_G1RemSet: public G1RemSet {
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132 protected:
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133 enum SomePrivateConstants {
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134 UpdateRStoMergeSync = 0,
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135 MergeRStoDoDirtySync = 1,
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136 DoDirtySync = 2,
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137 LastSync = 3,
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138
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139 SeqTask = 0,
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140 NumSeqTasks = 1
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141 };
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142
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143 CardTableModRefBS* _ct_bs;
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144 SubTasksDone* _seq_task;
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145 G1CollectorPolicy* _g1p;
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146
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147 ConcurrentG1Refine* _cg1r;
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148
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149 size_t* _cards_scanned;
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150 size_t _total_cards_scanned;
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151
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152 // _par_traversal_in_progress is "true" iff a parallel traversal is in
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153 // progress. If so, then cards added to remembered sets should also have
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154 // their references into the collection summarized in "_new_refs".
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155 bool _par_traversal_in_progress;
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156 void set_par_traversal(bool b);
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157 GrowableArray<oop*>** _new_refs;
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158
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159 public:
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160 // This is called to reset dual hash tables after the gc pause
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161 // is finished and the initial hash table is no longer being
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162 // scanned.
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163 void cleanupHRRS();
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164
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165 HRInto_G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
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166 ~HRInto_G1RemSet();
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167
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168 void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
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169 int worker_i);
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170
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171 void prepare_for_oops_into_collection_set_do();
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172 void cleanup_after_oops_into_collection_set_do();
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173 void scanRS(OopsInHeapRegionClosure* oc, int worker_i);
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174 void scanNewRefsRS(OopsInHeapRegionClosure* oc, int worker_i);
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175 void updateRS(int worker_i);
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176 HeapRegion* calculateStartRegion(int i);
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177
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178 HRInto_G1RemSet* as_HRInto_G1RemSet() { return this; }
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179
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180 CardTableModRefBS* ct_bs() { return _ct_bs; }
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181 size_t cardsScanned() { return _total_cards_scanned; }
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182
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183 // Record, if necessary, the fact that *p (where "p" is in region "from",
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184 // which is required to be non-NULL) has changed to a new non-NULL value.
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185 inline void write_ref(HeapRegion* from, oop* p);
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186 // The "_nv" version is the same; it exists just so that it is not virtual.
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187 inline void write_ref_nv(HeapRegion* from, oop* p);
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188
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189 inline bool self_forwarded(oop obj);
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190 inline void par_write_ref(HeapRegion* from, oop* p, int tid);
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191
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192 void scrub(BitMap* region_bm, BitMap* card_bm);
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193 void scrub_par(BitMap* region_bm, BitMap* card_bm,
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194 int worker_num, int claim_val);
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195
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196 virtual void concurrentRefinementPass(ConcurrentG1Refine* t);
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197 virtual void concurrentRefineOneCard(jbyte* card_ptr, int worker_i);
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198
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199 virtual void print_summary_info();
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200 virtual void prepare_for_verify();
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201 };
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202
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203 #define G1_REM_SET_LOGGING 0
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204
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205 class CountNonCleanMemRegionClosure: public MemRegionClosure {
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206 G1CollectedHeap* _g1;
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207 int _n;
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208 HeapWord* _start_first;
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209 public:
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210 CountNonCleanMemRegionClosure(G1CollectedHeap* g1) :
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211 _g1(g1), _n(0), _start_first(NULL)
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212 {}
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213 void do_MemRegion(MemRegion mr);
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214 int n() { return _n; };
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215 HeapWord* start_first() { return _start_first; }
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216 };
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