Mercurial > hg > graal-compiler
annotate src/share/vm/memory/genRemSet.hpp @ 1716:be3f9c242c9d
6948538: CMS: BOT walkers can fall into object allocation and initialization cracks
Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode.
Reviewed-by: chrisphi, johnc, poonam
| author | ysr |
|---|---|
| date | Mon, 16 Aug 2010 15:58:42 -0700 |
| parents | c18cbe5936b8 |
| children | f95d63e2154a |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 25 // A GenRemSet provides ways of iterating over pointers accross generations. | |
| 26 // (This is especially useful for older-to-younger.) | |
| 27 | |
| 28 class Generation; | |
| 29 class BarrierSet; | |
| 30 class OopsInGenClosure; | |
| 31 class CardTableRS; | |
| 32 | |
| 33 class GenRemSet: public CHeapObj { | |
| 34 friend class Generation; | |
| 35 | |
| 36 BarrierSet* _bs; | |
| 37 | |
| 38 public: | |
| 39 enum Name { | |
| 40 CardTable, | |
| 41 Other | |
| 42 }; | |
| 43 | |
| 44 GenRemSet(BarrierSet * bs) : _bs(bs) {} | |
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45 GenRemSet() : _bs(NULL) {} |
| 0 | 46 |
| 47 virtual Name rs_kind() = 0; | |
| 48 | |
| 49 // These are for dynamic downcasts. Unfortunately that it names the | |
| 50 // possible subtypes (but not that they are subtypes!) Return NULL if | |
| 51 // the cast is invalide. | |
| 52 virtual CardTableRS* as_CardTableRS() { return NULL; } | |
| 53 | |
| 54 // Return the barrier set associated with "this." | |
| 55 BarrierSet* bs() { return _bs; } | |
| 56 | |
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57 // Set the barrier set. |
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58 void set_bs(BarrierSet* bs) { _bs = bs; } |
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59 |
| 0 | 60 // Do any (sequential) processing necessary to prepare for (possibly |
| 61 // "parallel", if that arg is true) calls to younger_refs_iterate. | |
| 62 virtual void prepare_for_younger_refs_iterate(bool parallel) = 0; | |
| 63 | |
| 64 // Apply the "do_oop" method of "blk" to (exactly) all oop locations | |
| 65 // 1) that are in objects allocated in "g" at the time of the last call | |
| 66 // to "save_Marks", and | |
| 67 // 2) that point to objects in younger generations. | |
| 68 virtual void younger_refs_iterate(Generation* g, OopsInGenClosure* blk) = 0; | |
| 69 | |
| 70 virtual void younger_refs_in_space_iterate(Space* sp, | |
| 71 OopsInGenClosure* cl) = 0; | |
| 72 | |
| 73 // This method is used to notify the remembered set that "new_val" has | |
| 74 // been written into "field" by the garbage collector. | |
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75 void write_ref_field_gc(void* field, oop new_val); |
| 0 | 76 protected: |
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77 virtual void write_ref_field_gc_work(void* field, oop new_val) = 0; |
| 0 | 78 public: |
| 79 | |
| 80 // A version of the above suitable for use by parallel collectors. | |
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81 virtual void write_ref_field_gc_par(void* field, oop new_val) = 0; |
| 0 | 82 |
| 83 // Resize one of the regions covered by the remembered set. | |
| 84 virtual void resize_covered_region(MemRegion new_region) = 0; | |
| 85 | |
| 86 // If the rem set imposes any alignment restrictions on boundaries | |
| 87 // within the heap, this function tells whether they are met. | |
| 88 virtual bool is_aligned(HeapWord* addr) = 0; | |
| 89 | |
| 90 // If the RS (or BS) imposes an aligment constraint on maximum heap size. | |
| 91 // (This must be static, and dispatch on "nm", because it is called | |
| 92 // before an RS is created.) | |
| 93 static uintx max_alignment_constraint(Name nm); | |
| 94 | |
| 95 virtual void verify() = 0; | |
| 96 | |
| 97 // Verify that the remembered set has no entries for | |
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98 // the heap interval denoted by mr. If there are any |
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99 // alignment constraints on the remembered set, only the |
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100 // part of the region that is aligned is checked. |
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101 // |
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102 // alignment boundaries |
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103 // +--------+-------+--------+-------+ |
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104 // [ region mr ) |
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105 // [ part checked ) |
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106 virtual void verify_aligned_region_empty(MemRegion mr) = 0; |
| 0 | 107 |
| 108 // If appropriate, print some information about the remset on "tty". | |
| 109 virtual void print() {} | |
| 110 | |
| 111 // Informs the RS that the given memregion contains no references to | |
| 112 // younger generations. | |
| 113 virtual void clear(MemRegion mr) = 0; | |
| 114 | |
| 115 // Informs the RS that there are no references to generations | |
| 116 // younger than gen from generations gen and older. | |
| 117 // The parameter clear_perm indicates if the perm_gen's | |
| 118 // remembered set should also be processed/cleared. | |
| 119 virtual void clear_into_younger(Generation* gen, bool clear_perm) = 0; | |
| 120 | |
| 121 // Informs the RS that refs in the given "mr" may have changed | |
| 122 // arbitrarily, and therefore may contain old-to-young pointers. | |
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123 // If "whole heap" is true, then this invalidation is part of an |
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124 // invalidation of the whole heap, which an implementation might |
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125 // handle differently than that of a sub-part of the heap. |
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126 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0; |
| 0 | 127 |
| 128 // Informs the RS that refs in this generation | |
| 129 // may have changed arbitrarily, and therefore may contain | |
| 130 // old-to-young pointers in arbitrary locations. The parameter | |
| 131 // younger indicates if the same should be done for younger generations | |
| 132 // as well. The parameter perm indicates if the same should be done for | |
| 133 // perm gen as well. | |
| 134 virtual void invalidate_or_clear(Generation* gen, bool younger, bool perm) = 0; | |
| 135 }; |