Mercurial > hg > truffle
annotate src/share/vm/memory/iterator.hpp @ 935:05f89f00a864
6798898: CMS: bugs related to class unloading
Summary: Override should_remember_klasses() and remember_klass() as needed.
Reviewed-by: ysr, jcoomes
| author | jmasa |
|---|---|
| date | Mon, 24 Aug 2009 10:36:31 -0700 |
| parents | 1ee8caae33af |
| children | 8b46c4d82093 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 196 | 2 * Copyright 1997-2008 Sun Microsystems, Inc. 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 * | |
| 19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 // The following classes are C++ `closures` for iterating over objects, roots and spaces | |
| 26 | |
| 27 class ReferenceProcessor; | |
| 28 | |
|
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29 // Closure provides abortability. |
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30 |
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31 class Closure : public StackObj { |
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32 protected: |
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33 bool _abort; |
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34 void set_abort() { _abort = true; } |
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35 public: |
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36 Closure() : _abort(false) {} |
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37 // A subtype can use this mechanism to indicate to some iterator mapping |
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38 // functions that the iteration should cease. |
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39 bool abort() { return _abort; } |
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40 void clear_abort() { _abort = false; } |
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41 }; |
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42 |
| 0 | 43 // OopClosure is used for iterating through roots (oop*) |
| 44 | |
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45 class OopClosure : public Closure { |
| 0 | 46 public: |
| 47 ReferenceProcessor* _ref_processor; | |
| 48 OopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { } | |
| 49 OopClosure() : _ref_processor(NULL) { } | |
| 50 virtual void do_oop(oop* o) = 0; | |
| 51 virtual void do_oop_v(oop* o) { do_oop(o); } | |
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52 virtual void do_oop(narrowOop* o) = 0; |
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53 virtual void do_oop_v(narrowOop* o) { do_oop(o); } |
| 0 | 54 |
| 55 // In support of post-processing of weak links of KlassKlass objects; | |
| 56 // see KlassKlass::oop_oop_iterate(). | |
| 935 | 57 |
| 58 virtual const bool should_remember_klasses() const { | |
| 59 assert(!must_remember_klasses(), "Should have overriden this method."); | |
| 60 return false; | |
| 61 } | |
| 62 | |
| 0 | 63 virtual void remember_klass(Klass* k) { /* do nothing */ } |
| 64 | |
| 65 // If "true", invoke on nmethods (when scanning compiled frames). | |
| 66 virtual const bool do_nmethods() const { return false; } | |
| 67 | |
| 68 // The methods below control how object iterations invoking this closure | |
| 69 // should be performed: | |
| 70 | |
| 71 // If "true", invoke on header klass field. | |
| 72 bool do_header() { return true; } // Note that this is non-virtual. | |
| 73 // Controls how prefetching is done for invocations of this closure. | |
| 74 Prefetch::style prefetch_style() { // Note that this is non-virtual. | |
| 75 return Prefetch::do_none; | |
| 76 } | |
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77 |
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78 // True iff this closure may be safely applied more than once to an oop |
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79 // location without an intervening "major reset" (like the end of a GC). |
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80 virtual bool idempotent() { return false; } |
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81 virtual bool apply_to_weak_ref_discovered_field() { return false; } |
| 935 | 82 |
| 83 #ifdef ASSERT | |
| 84 static bool _must_remember_klasses; | |
| 85 static bool must_remember_klasses(); | |
| 86 static void set_must_remember_klasses(bool v); | |
| 87 #endif | |
| 0 | 88 }; |
| 89 | |
| 90 // ObjectClosure is used for iterating through an object space | |
| 91 | |
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92 class ObjectClosure : public Closure { |
| 0 | 93 public: |
| 94 // Called for each object. | |
| 95 virtual void do_object(oop obj) = 0; | |
| 96 }; | |
| 97 | |
| 98 | |
| 99 class BoolObjectClosure : public ObjectClosure { | |
| 100 public: | |
| 101 virtual bool do_object_b(oop obj) = 0; | |
| 102 }; | |
| 103 | |
| 104 // Applies an oop closure to all ref fields in objects iterated over in an | |
| 105 // object iteration. | |
| 106 class ObjectToOopClosure: public ObjectClosure { | |
| 107 OopClosure* _cl; | |
| 108 public: | |
| 109 void do_object(oop obj); | |
| 110 ObjectToOopClosure(OopClosure* cl) : _cl(cl) {} | |
| 111 }; | |
| 112 | |
| 113 // A version of ObjectClosure with "memory" (see _previous_address below) | |
| 114 class UpwardsObjectClosure: public BoolObjectClosure { | |
| 115 HeapWord* _previous_address; | |
| 116 public: | |
| 117 UpwardsObjectClosure() : _previous_address(NULL) { } | |
| 118 void set_previous(HeapWord* addr) { _previous_address = addr; } | |
| 119 HeapWord* previous() { return _previous_address; } | |
| 120 // A return value of "true" can be used by the caller to decide | |
| 121 // if this object's end should *NOT* be recorded in | |
| 122 // _previous_address above. | |
| 123 virtual bool do_object_bm(oop obj, MemRegion mr) = 0; | |
| 124 }; | |
| 125 | |
| 126 // A version of ObjectClosure that is expected to be robust | |
| 127 // in the face of possibly uninitialized objects. | |
| 128 class ObjectClosureCareful : public ObjectClosure { | |
| 129 public: | |
| 130 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0; | |
| 131 virtual size_t do_object_careful(oop p) = 0; | |
| 132 }; | |
| 133 | |
| 134 // The following are used in CompactibleFreeListSpace and | |
| 135 // ConcurrentMarkSweepGeneration. | |
| 136 | |
| 137 // Blk closure (abstract class) | |
| 138 class BlkClosure : public StackObj { | |
| 139 public: | |
| 140 virtual size_t do_blk(HeapWord* addr) = 0; | |
| 141 }; | |
| 142 | |
| 143 // A version of BlkClosure that is expected to be robust | |
| 144 // in the face of possibly uninitialized objects. | |
| 145 class BlkClosureCareful : public BlkClosure { | |
| 146 public: | |
| 147 size_t do_blk(HeapWord* addr) { | |
| 148 guarantee(false, "call do_blk_careful instead"); | |
| 149 return 0; | |
| 150 } | |
| 151 virtual size_t do_blk_careful(HeapWord* addr) = 0; | |
| 152 }; | |
| 153 | |
| 154 // SpaceClosure is used for iterating over spaces | |
| 155 | |
| 156 class Space; | |
| 157 class CompactibleSpace; | |
| 158 | |
| 159 class SpaceClosure : public StackObj { | |
| 160 public: | |
| 161 // Called for each space | |
| 162 virtual void do_space(Space* s) = 0; | |
| 163 }; | |
| 164 | |
| 165 class CompactibleSpaceClosure : public StackObj { | |
| 166 public: | |
| 167 // Called for each compactible space | |
| 168 virtual void do_space(CompactibleSpace* s) = 0; | |
| 169 }; | |
| 170 | |
| 171 | |
| 172 | |
| 173 // MonitorClosure is used for iterating over monitors in the monitors cache | |
| 174 | |
| 175 class ObjectMonitor; | |
| 176 | |
| 177 class MonitorClosure : public StackObj { | |
| 178 public: | |
| 179 // called for each monitor in cache | |
| 180 virtual void do_monitor(ObjectMonitor* m) = 0; | |
| 181 }; | |
| 182 | |
| 183 // A closure that is applied without any arguments. | |
| 184 class VoidClosure : public StackObj { | |
| 185 public: | |
| 186 // I would have liked to declare this a pure virtual, but that breaks | |
| 187 // in mysterious ways, for unknown reasons. | |
| 188 virtual void do_void(); | |
| 189 }; | |
| 190 | |
| 191 | |
| 192 // YieldClosure is intended for use by iteration loops | |
| 193 // to incrementalize their work, allowing interleaving | |
| 194 // of an interruptable task so as to allow other | |
| 195 // threads to run (which may not otherwise be able to access | |
| 196 // exclusive resources, for instance). Additionally, the | |
| 197 // closure also allows for aborting an ongoing iteration | |
| 198 // by means of checking the return value from the polling | |
| 199 // call. | |
| 200 class YieldClosure : public StackObj { | |
| 201 public: | |
| 202 virtual bool should_return() = 0; | |
| 203 }; | |
| 204 | |
| 205 // Abstract closure for serializing data (read or write). | |
| 206 | |
| 207 class SerializeOopClosure : public OopClosure { | |
| 208 public: | |
| 209 // Return bool indicating whether closure implements read or write. | |
| 210 virtual bool reading() const = 0; | |
| 211 | |
| 212 // Read/write the int pointed to by i. | |
| 213 virtual void do_int(int* i) = 0; | |
| 214 | |
| 215 // Read/write the size_t pointed to by i. | |
| 216 virtual void do_size_t(size_t* i) = 0; | |
| 217 | |
| 218 // Read/write the void pointer pointed to by p. | |
| 219 virtual void do_ptr(void** p) = 0; | |
| 220 | |
| 221 // Read/write the HeapWord pointer pointed to be p. | |
| 222 virtual void do_ptr(HeapWord** p) = 0; | |
| 223 | |
| 224 // Read/write the region specified. | |
| 225 virtual void do_region(u_char* start, size_t size) = 0; | |
| 226 | |
| 227 // Check/write the tag. If reading, then compare the tag against | |
| 228 // the passed in value and fail is they don't match. This allows | |
| 229 // for verification that sections of the serialized data are of the | |
| 230 // correct length. | |
| 231 virtual void do_tag(int tag) = 0; | |
| 232 }; | |
| 935 | 233 |
| 234 #ifdef ASSERT | |
| 235 // This class is used to flag phases of a collection that | |
| 236 // can unload classes and which should override the | |
| 237 // should_remember_klasses() and remember_klass() of OopClosure. | |
| 238 // The _must_remember_klasses is set in the contructor and restored | |
| 239 // in the destructor. _must_remember_klasses is checked in assertions | |
| 240 // in the OopClosure implementations of should_remember_klasses() and | |
| 241 // remember_klass() and the expectation is that the OopClosure | |
| 242 // implementation should not be in use if _must_remember_klasses is set. | |
| 243 // Instances of RememberKlassesChecker can be place in | |
| 244 // marking phases of collections which can do class unloading. | |
| 245 // RememberKlassesChecker can be passed "false" to turn off checking. | |
| 246 // It is used by CMS when CMS yields to a different collector. | |
| 247 class RememberKlassesChecker: StackObj { | |
| 248 bool _state; | |
| 249 bool _skip; | |
| 250 public: | |
| 251 RememberKlassesChecker(bool checking_on) : _state(false), _skip(false) { | |
| 252 _skip = !(ClassUnloading && !UseConcMarkSweepGC || | |
| 253 CMSClassUnloadingEnabled && UseConcMarkSweepGC); | |
| 254 if (_skip) { | |
| 255 return; | |
| 256 } | |
| 257 _state = OopClosure::must_remember_klasses(); | |
| 258 OopClosure::set_must_remember_klasses(checking_on); | |
| 259 } | |
| 260 ~RememberKlassesChecker() { | |
| 261 if (_skip) { | |
| 262 return; | |
| 263 } | |
| 264 OopClosure::set_must_remember_klasses(_state); | |
| 265 } | |
| 266 }; | |
| 267 #endif // ASSERT |