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1 /*
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2 * Copyright 2001-2006 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 GenRemSet provides ways of iterating over pointers accross generations.
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26 // (This is especially useful for older-to-younger.)
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27
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28 class Generation;
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29 class BarrierSet;
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30 class OopsInGenClosure;
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31 class CardTableRS;
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32
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33 class GenRemSet: public CHeapObj {
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34 friend class Generation;
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35
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36 BarrierSet* _bs;
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37
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38 public:
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39 enum Name {
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40 CardTable,
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41 Other
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42 };
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43
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44 GenRemSet(BarrierSet * bs) : _bs(bs) {}
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45
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46 virtual Name rs_kind() = 0;
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47
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48 // These are for dynamic downcasts. Unfortunately that it names the
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49 // possible subtypes (but not that they are subtypes!) Return NULL if
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50 // the cast is invalide.
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51 virtual CardTableRS* as_CardTableRS() { return NULL; }
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52
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53 // Return the barrier set associated with "this."
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54 BarrierSet* bs() { return _bs; }
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55
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56 // Do any (sequential) processing necessary to prepare for (possibly
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57 // "parallel", if that arg is true) calls to younger_refs_iterate.
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58 virtual void prepare_for_younger_refs_iterate(bool parallel) = 0;
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59
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60 // Apply the "do_oop" method of "blk" to (exactly) all oop locations
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61 // 1) that are in objects allocated in "g" at the time of the last call
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62 // to "save_Marks", and
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63 // 2) that point to objects in younger generations.
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64 virtual void younger_refs_iterate(Generation* g, OopsInGenClosure* blk) = 0;
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65
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66 virtual void younger_refs_in_space_iterate(Space* sp,
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67 OopsInGenClosure* cl) = 0;
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68
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69 // This method is used to notify the remembered set that "new_val" has
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70 // been written into "field" by the garbage collector.
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71 void write_ref_field_gc(oop* field, oop new_val);
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72 protected:
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73 virtual void write_ref_field_gc_work(oop* field, oop new_val) = 0;
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74 public:
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75
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76 // A version of the above suitable for use by parallel collectors.
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77 virtual void write_ref_field_gc_par(oop* field, oop new_val) = 0;
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78
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79 // Resize one of the regions covered by the remembered set.
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80 virtual void resize_covered_region(MemRegion new_region) = 0;
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81
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82 // If the rem set imposes any alignment restrictions on boundaries
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83 // within the heap, this function tells whether they are met.
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84 virtual bool is_aligned(HeapWord* addr) = 0;
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85
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86 // If the RS (or BS) imposes an aligment constraint on maximum heap size.
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87 // (This must be static, and dispatch on "nm", because it is called
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88 // before an RS is created.)
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89 static uintx max_alignment_constraint(Name nm);
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90
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91 virtual void verify() = 0;
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92
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93 // Verify that the remembered set has no entries for
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94 // the heap interval denoted by mr.
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95 virtual void verify_empty(MemRegion mr) = 0;
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96
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97 // If appropriate, print some information about the remset on "tty".
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98 virtual void print() {}
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99
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100 // Informs the RS that the given memregion contains no references to
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101 // younger generations.
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102 virtual void clear(MemRegion mr) = 0;
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103
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104 // Informs the RS that there are no references to generations
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105 // younger than gen from generations gen and older.
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106 // The parameter clear_perm indicates if the perm_gen's
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107 // remembered set should also be processed/cleared.
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108 virtual void clear_into_younger(Generation* gen, bool clear_perm) = 0;
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109
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110 // Informs the RS that refs in the given "mr" may have changed
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111 // arbitrarily, and therefore may contain old-to-young pointers.
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112 virtual void invalidate(MemRegion mr) = 0;
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113
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114 // Informs the RS that refs in this generation
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115 // may have changed arbitrarily, and therefore may contain
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116 // old-to-young pointers in arbitrary locations. The parameter
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117 // younger indicates if the same should be done for younger generations
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118 // as well. The parameter perm indicates if the same should be done for
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119 // perm gen as well.
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120 virtual void invalidate_or_clear(Generation* gen, bool younger, bool perm) = 0;
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121 };
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