38 class Symbol;
39
40 // The following classes are C++ `closures` for iterating over objects, roots and spaces
41
42 class Closure : public StackObj { };
43
44 // OopClosure is used for iterating through references to Java objects.
45 class OopClosure : public Closure {
46 public:
47 virtual void do_oop(oop* o) = 0;
48 virtual void do_oop(narrowOop* o) = 0;
49 };
50
51 class DoNothingClosure : public OopClosure {
52 public:
53 virtual void do_oop(oop* p) {}
54 virtual void do_oop(narrowOop* p) {}
55 };
56 extern DoNothingClosure do_nothing_cl;
57
58 // ExtendedOopClosure adds extra code to be run during oop iterations.
59 // This is needed by the GC and is extracted to a separate type to not
60 // pollute the OopClosure interface.
61 class ExtendedOopClosure : public OopClosure {
62 private:
63 ReferenceDiscoverer* _ref_discoverer;
64
65 protected:
66 ExtendedOopClosure(ReferenceDiscoverer* rd) : _ref_discoverer(rd) { }
67 ExtendedOopClosure() : _ref_discoverer(NULL) { }
68 ~ExtendedOopClosure() { }
69
70 void set_ref_discoverer_internal(ReferenceDiscoverer* rd) { _ref_discoverer = rd; }
71
72 public:
73 ReferenceDiscoverer* ref_discoverer() const { return _ref_discoverer; }
74
75 // Iteration of InstanceRefKlasses differ depending on the closure,
76 // the below enum describes the different alternatives.
77 enum ReferenceIterationMode {
78 DO_DISCOVERY, // Apply closure and discover references
79 DO_DISCOVERED_AND_DISCOVERY, // Apply closure to discovered field and do discovery
80 DO_FIELDS // Apply closure to all fields
81 };
82
83 // The default iteration mode is to do discovery.
84 virtual ReferenceIterationMode reference_iteration_mode() { return DO_DISCOVERY; }
85
86 // If the do_metadata functions return "true",
87 // we invoke the following when running oop_iterate():
88 //
89 // 1) do_klass on the header klass pointer.
90 // 2) do_klass on the klass pointer in the mirrors.
91 // 3) do_cld on the class loader data in class loaders.
92 //
93 // The virtual (without suffix) and the non-virtual (with _nv suffix) need
94 // to be updated together, or else the devirtualization will break.
95 //
96 // Providing default implementations of the _nv functions unfortunately
97 // removes the compile-time safeness, but reduces the clutter for the
98 // ExtendedOopClosures that don't need to walk the metadata.
99 // Currently, only CMS and G1 need these.
100
101 bool do_metadata_nv() { return false; }
102 virtual bool do_metadata() { return do_metadata_nv(); }
103
104 void do_klass_nv(Klass* k) { ShouldNotReachHere(); }
105 virtual void do_klass(Klass* k) { do_klass_nv(k); }
106
107 void do_cld_nv(ClassLoaderData* cld) { ShouldNotReachHere(); }
108 virtual void do_cld(ClassLoaderData* cld) { do_cld_nv(cld); }
109
110 // True iff this closure may be safely applied more than once to an oop
111 // location without an intervening "major reset" (like the end of a GC).
112 virtual bool idempotent() { return false; }
113
114 #ifdef ASSERT
115 // Default verification of each visited oop field.
116 template <typename T> void verify(T* p);
117
118 // Can be used by subclasses to turn off the default verification of oop fields.
119 virtual bool should_verify_oops() { return true; }
120 #endif
121 };
122
123 // Wrapper closure only used to implement oop_iterate_no_header().
124 class NoHeaderExtendedOopClosure : public ExtendedOopClosure {
125 OopClosure* _wrapped_closure;
126 public:
127 NoHeaderExtendedOopClosure(OopClosure* cl) : _wrapped_closure(cl) {}
128 // Warning: this calls the virtual version do_oop in the the wrapped closure.
129 void do_oop_nv(oop* p) { _wrapped_closure->do_oop(p); }
130 void do_oop_nv(narrowOop* p) { _wrapped_closure->do_oop(p); }
131
132 void do_oop(oop* p) { assert(false, "Only the _nv versions should be used");
133 _wrapped_closure->do_oop(p); }
134 void do_oop(narrowOop* p) { assert(false, "Only the _nv versions should be used");
135 _wrapped_closure->do_oop(p);}
136 };
137
138 class KlassClosure : public Closure {
139 public:
140 virtual void do_klass(Klass* k) = 0;
141 };
142
143 class CLDClosure : public Closure {
144 public:
145 virtual void do_cld(ClassLoaderData* cld) = 0;
146 };
147
148
149 class CLDToOopClosure : public CLDClosure {
150 OopClosure* _oop_closure;
151 bool _must_claim_cld;
152
153 public:
154 CLDToOopClosure(OopClosure* oop_closure, bool must_claim_cld = true) :
155 _oop_closure(oop_closure),
156 _must_claim_cld(must_claim_cld) {}
157
158 void do_cld(ClassLoaderData* cld);
159 };
160
161 // The base class for all concurrent marking closures,
162 // that participates in class unloading.
163 // It's used to proxy through the metadata to the oops defined in them.
164 class MetadataAwareOopClosure: public ExtendedOopClosure {
165
166 public:
167 MetadataAwareOopClosure() : ExtendedOopClosure() { }
168 MetadataAwareOopClosure(ReferenceDiscoverer* rd) : ExtendedOopClosure(rd) { }
169
170 bool do_metadata_nv() { return true; }
171 virtual bool do_metadata() { return do_metadata_nv(); }
172
173 void do_klass_nv(Klass* k);
174 virtual void do_klass(Klass* k) { do_klass_nv(k); }
175
176 void do_cld_nv(ClassLoaderData* cld);
177 virtual void do_cld(ClassLoaderData* cld) { do_cld_nv(cld); }
178 };
179
180 // ObjectClosure is used for iterating through an object space
181
182 class ObjectClosure : public Closure {
183 public:
184 // Called for each object.
185 virtual void do_object(oop obj) = 0;
186 };
187
188
189 class BoolObjectClosure : public Closure {
190 public:
191 virtual bool do_object_b(oop obj) = 0;
192 };
193
194 class AlwaysTrueClosure: public BoolObjectClosure {
195 public:
196 bool do_object_b(oop p) { return true; }
197 };
198
199 class AlwaysFalseClosure : public BoolObjectClosure {
200 public:
201 bool do_object_b(oop p) { return false; }
202 };
203
204 // Applies an oop closure to all ref fields in objects iterated over in an
205 // object iteration.
206 class ObjectToOopClosure: public ObjectClosure {
207 ExtendedOopClosure* _cl;
208 public:
209 void do_object(oop obj);
210 ObjectToOopClosure(ExtendedOopClosure* cl) : _cl(cl) {}
211 };
212
213 // A version of ObjectClosure that is expected to be robust
214 // in the face of possibly uninitialized objects.
215 class ObjectClosureCareful : public ObjectClosure {
216 public:
217 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
218 virtual size_t do_object_careful(oop p) = 0;
219 };
220
221 // The following are used in CompactibleFreeListSpace and
222 // ConcurrentMarkSweepGeneration.
223
224 // Blk closure (abstract class)
225 class BlkClosure : public StackObj {
226 public:
227 virtual size_t do_blk(HeapWord* addr) = 0;
228 };
229
230 // A version of BlkClosure that is expected to be robust
354 return !reading();
355 }
356 };
357
358 class SymbolClosure : public StackObj {
359 public:
360 virtual void do_symbol(Symbol**) = 0;
361
362 // Clear LSB in symbol address; it can be set by CPSlot.
363 static Symbol* load_symbol(Symbol** p) {
364 return (Symbol*)(intptr_t(*p) & ~1);
365 }
366
367 // Store symbol, adjusting new pointer if the original pointer was adjusted
368 // (symbol references in constant pool slots have their LSB set to 1).
369 static void store_symbol(Symbol** p, Symbol* sym) {
370 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1));
371 }
372 };
373
374 // The two class template specializations are used to dispatch calls
375 // to the ExtendedOopClosure functions. If use_non_virtual_call is true,
376 // the non-virtual versions are called (E.g. do_oop_nv), otherwise the
377 // virtual versions are called (E.g. do_oop).
378
379 template <bool use_non_virtual_call>
380 class Devirtualizer {};
381
382 // Dispatches to the non-virtual functions.
383 template <> class Devirtualizer<true> {
384 public:
385 template <class OopClosureType, typename T> static void do_oop(OopClosureType* closure, T* p);
386 template <class OopClosureType> static void do_klass(OopClosureType* closure, Klass* k);
387 template <class OopClosureType> static void do_cld(OopClosureType* closure, ClassLoaderData* cld);
388 template <class OopClosureType> static bool do_metadata(OopClosureType* closure);
389 };
390
391 // Dispatches to the virtual functions.
392 template <> class Devirtualizer<false> {
393 public:
394 template <class OopClosureType, typename T> static void do_oop(OopClosureType* closure, T* p);
395 template <class OopClosureType> static void do_klass(OopClosureType* closure, Klass* k);
396 template <class OopClosureType> static void do_cld(OopClosureType* closure, ClassLoaderData* cld);
397 template <class OopClosureType> static bool do_metadata(OopClosureType* closure);
398 };
399
400 #endif // SHARE_VM_MEMORY_ITERATOR_HPP
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38 class Symbol;
39
40 // The following classes are C++ `closures` for iterating over objects, roots and spaces
41
42 class Closure : public StackObj { };
43
44 // OopClosure is used for iterating through references to Java objects.
45 class OopClosure : public Closure {
46 public:
47 virtual void do_oop(oop* o) = 0;
48 virtual void do_oop(narrowOop* o) = 0;
49 };
50
51 class DoNothingClosure : public OopClosure {
52 public:
53 virtual void do_oop(oop* p) {}
54 virtual void do_oop(narrowOop* p) {}
55 };
56 extern DoNothingClosure do_nothing_cl;
57
58 // OopIterateClosure adds extra code to be run during oop iterations.
59 // This is needed by the GC and is extracted to a separate type to not
60 // pollute the OopClosure interface.
61 class OopIterateClosure : public OopClosure {
62 private:
63 ReferenceDiscoverer* _ref_discoverer;
64
65 protected:
66 OopIterateClosure(ReferenceDiscoverer* rd) : _ref_discoverer(rd) { }
67 OopIterateClosure() : _ref_discoverer(NULL) { }
68 ~OopIterateClosure() { }
69
70 void set_ref_discoverer_internal(ReferenceDiscoverer* rd) { _ref_discoverer = rd; }
71
72 public:
73 ReferenceDiscoverer* ref_discoverer() const { return _ref_discoverer; }
74
75 // Iteration of InstanceRefKlasses differ depending on the closure,
76 // the below enum describes the different alternatives.
77 enum ReferenceIterationMode {
78 DO_DISCOVERY, // Apply closure and discover references
79 DO_DISCOVERED_AND_DISCOVERY, // Apply closure to discovered field and do discovery
80 DO_FIELDS // Apply closure to all fields
81 };
82
83 // The default iteration mode is to do discovery.
84 virtual ReferenceIterationMode reference_iteration_mode() { return DO_DISCOVERY; }
85
86 // If the do_metadata functions return "true",
87 // we invoke the following when running oop_iterate():
88 //
89 // 1) do_klass on the header klass pointer.
90 // 2) do_klass on the klass pointer in the mirrors.
91 // 3) do_cld on the class loader data in class loaders.
92
93 virtual bool do_metadata() = 0;
94 virtual void do_klass(Klass* k) = 0;
95 virtual void do_cld(ClassLoaderData* cld) = 0;
96
97 // True iff this closure may be safely applied more than once to an oop
98 // location without an intervening "major reset" (like the end of a GC).
99 virtual bool idempotent() { return false; }
100
101 #ifdef ASSERT
102 // Default verification of each visited oop field.
103 template <typename T> void verify(T* p);
104
105 // Can be used by subclasses to turn off the default verification of oop fields.
106 virtual bool should_verify_oops() { return true; }
107 #endif
108 };
109
110 // An OopIterateClosure that can be used when there's no need to visit the Metadata.
111 class BasicOopIterateClosure : public OopIterateClosure {
112 public:
113 BasicOopIterateClosure(ReferenceDiscoverer* rd = NULL) : OopIterateClosure(rd) {}
114
115 virtual bool do_metadata() { return false; }
116 virtual void do_klass(Klass* k) { ShouldNotReachHere(); }
117 virtual void do_cld(ClassLoaderData* cld) { ShouldNotReachHere(); }
118 };
119
120 // Wrapper closure only used to implement oop_iterate_no_header().
121 class NoHeaderExtendedOopClosure : public BasicOopIterateClosure {
122 OopClosure* _wrapped_closure;
123 public:
124 NoHeaderExtendedOopClosure(OopClosure* cl) : _wrapped_closure(cl) {}
125 // Warning: this calls the virtual version do_oop in the the wrapped closure.
126 virtual void do_oop(oop* p) { _wrapped_closure->do_oop(p); }
127 virtual void do_oop(narrowOop* p) { _wrapped_closure->do_oop(p); }
128 };
129
130 class KlassClosure : public Closure {
131 public:
132 virtual void do_klass(Klass* k) = 0;
133 };
134
135 class CLDClosure : public Closure {
136 public:
137 virtual void do_cld(ClassLoaderData* cld) = 0;
138 };
139
140
141 class CLDToOopClosure : public CLDClosure {
142 OopClosure* _oop_closure;
143 bool _must_claim_cld;
144
145 public:
146 CLDToOopClosure(OopClosure* oop_closure, bool must_claim_cld = true) :
147 _oop_closure(oop_closure),
148 _must_claim_cld(must_claim_cld) {}
149
150 void do_cld(ClassLoaderData* cld);
151 };
152
153 // The base class for all concurrent marking closures,
154 // that participates in class unloading.
155 // It's used to proxy through the metadata to the oops defined in them.
156 class MetadataVisitingOopIterateClosure: public OopIterateClosure {
157 public:
158 MetadataVisitingOopIterateClosure(ReferenceDiscoverer* rd = NULL) : OopIterateClosure(rd) { }
159
160 virtual bool do_metadata() { return true; }
161 virtual void do_klass(Klass* k);
162 virtual void do_cld(ClassLoaderData* cld);
163 };
164
165 // ObjectClosure is used for iterating through an object space
166
167 class ObjectClosure : public Closure {
168 public:
169 // Called for each object.
170 virtual void do_object(oop obj) = 0;
171 };
172
173
174 class BoolObjectClosure : public Closure {
175 public:
176 virtual bool do_object_b(oop obj) = 0;
177 };
178
179 class AlwaysTrueClosure: public BoolObjectClosure {
180 public:
181 bool do_object_b(oop p) { return true; }
182 };
183
184 class AlwaysFalseClosure : public BoolObjectClosure {
185 public:
186 bool do_object_b(oop p) { return false; }
187 };
188
189 // Applies an oop closure to all ref fields in objects iterated over in an
190 // object iteration.
191 class ObjectToOopClosure: public ObjectClosure {
192 OopIterateClosure* _cl;
193 public:
194 void do_object(oop obj);
195 ObjectToOopClosure(OopIterateClosure* cl) : _cl(cl) {}
196 };
197
198 // A version of ObjectClosure that is expected to be robust
199 // in the face of possibly uninitialized objects.
200 class ObjectClosureCareful : public ObjectClosure {
201 public:
202 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
203 virtual size_t do_object_careful(oop p) = 0;
204 };
205
206 // The following are used in CompactibleFreeListSpace and
207 // ConcurrentMarkSweepGeneration.
208
209 // Blk closure (abstract class)
210 class BlkClosure : public StackObj {
211 public:
212 virtual size_t do_blk(HeapWord* addr) = 0;
213 };
214
215 // A version of BlkClosure that is expected to be robust
339 return !reading();
340 }
341 };
342
343 class SymbolClosure : public StackObj {
344 public:
345 virtual void do_symbol(Symbol**) = 0;
346
347 // Clear LSB in symbol address; it can be set by CPSlot.
348 static Symbol* load_symbol(Symbol** p) {
349 return (Symbol*)(intptr_t(*p) & ~1);
350 }
351
352 // Store symbol, adjusting new pointer if the original pointer was adjusted
353 // (symbol references in constant pool slots have their LSB set to 1).
354 static void store_symbol(Symbol** p, Symbol* sym) {
355 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1));
356 }
357 };
358
359 // Dispatches to the non-virtual functions if OopClosureType has
360 // a concrete implementation, otherwise a virtual call is taken.
361 class Devirtualizer {
362 public:
363 template <typename OopClosureType, typename T> static void do_oop_no_verify(OopClosureType* closure, T* p);
364 template <typename OopClosureType, typename T> static void do_oop(OopClosureType* closure, T* p);
365 template <typename OopClosureType> static void do_klass(OopClosureType* closure, Klass* k);
366 template <typename OopClosureType> static void do_cld(OopClosureType* closure, ClassLoaderData* cld);
367 template <typename OopClosureType> static bool do_metadata(OopClosureType* closure);
368 };
369
370 class OopClosureDispatch {
371 public:
372 template <typename OopClosureType> static void oop_oop_iterate(OopClosureType* cl, oop obj, Klass* klass);
373 template <typename OopClosureType> static void oop_oop_iterate(OopClosureType* cl, oop obj, Klass* klass, MemRegion mr);
374 template <typename OopClosureType> static void oop_oop_iterate_backwards(OopClosureType* cl, oop obj, Klass* klass);
375 };
376
377 #endif // SHARE_VM_MEMORY_ITERATOR_HPP
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