Thu, 26 Jun 2014 11:36:58 +0200
8047818: G1 HeapRegions can no longer be ContiguousSpaces
Summary: Change parent of G1OffsetTableContigSpace to CompactibleSpace, reimplement missing functionality
Reviewed-by: stefank, jmasa, tschatzl
1 /*
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25 #ifndef SHARE_VM_MEMORY_ITERATOR_HPP
26 #define SHARE_VM_MEMORY_ITERATOR_HPP
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "runtime/prefetch.hpp"
31 #include "utilities/top.hpp"
33 // The following classes are C++ `closures` for iterating over objects, roots and spaces
35 class CodeBlob;
36 class nmethod;
37 class ReferenceProcessor;
38 class DataLayout;
39 class KlassClosure;
40 class ClassLoaderData;
42 // Closure provides abortability.
44 class Closure : public StackObj {
45 protected:
46 bool _abort;
47 void set_abort() { _abort = true; }
48 public:
49 Closure() : _abort(false) {}
50 // A subtype can use this mechanism to indicate to some iterator mapping
51 // functions that the iteration should cease.
52 bool abort() { return _abort; }
53 void clear_abort() { _abort = false; }
54 };
56 // OopClosure is used for iterating through references to Java objects.
58 class OopClosure : public Closure {
59 public:
60 virtual void do_oop(oop* o) = 0;
61 virtual void do_oop_v(oop* o) { do_oop(o); }
62 virtual void do_oop(narrowOop* o) = 0;
63 virtual void do_oop_v(narrowOop* o) { do_oop(o); }
64 };
66 // ExtendedOopClosure adds extra code to be run during oop iterations.
67 // This is needed by the GC and is extracted to a separate type to not
68 // pollute the OopClosure interface.
69 class ExtendedOopClosure : public OopClosure {
70 public:
71 ReferenceProcessor* _ref_processor;
72 ExtendedOopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
73 ExtendedOopClosure() : OopClosure(), _ref_processor(NULL) { }
75 // If the do_metadata functions return "true",
76 // we invoke the following when running oop_iterate():
77 //
78 // 1) do_klass on the header klass pointer.
79 // 2) do_klass on the klass pointer in the mirrors.
80 // 3) do_class_loader_data on the class loader data in class loaders.
81 //
82 // The virtual (without suffix) and the non-virtual (with _nv suffix) need
83 // to be updated together, or else the devirtualization will break.
84 //
85 // Providing default implementations of the _nv functions unfortunately
86 // removes the compile-time safeness, but reduces the clutter for the
87 // ExtendedOopClosures that don't need to walk the metadata. Currently,
88 // only CMS needs these.
90 virtual bool do_metadata() { return do_metadata_nv(); }
91 bool do_metadata_v() { return do_metadata(); }
92 bool do_metadata_nv() { return false; }
94 virtual void do_klass(Klass* k) { do_klass_nv(k); }
95 void do_klass_v(Klass* k) { do_klass(k); }
96 void do_klass_nv(Klass* k) { ShouldNotReachHere(); }
98 virtual void do_class_loader_data(ClassLoaderData* cld) { ShouldNotReachHere(); }
100 // Controls how prefetching is done for invocations of this closure.
101 Prefetch::style prefetch_style() { // Note that this is non-virtual.
102 return Prefetch::do_none;
103 }
105 // True iff this closure may be safely applied more than once to an oop
106 // location without an intervening "major reset" (like the end of a GC).
107 virtual bool idempotent() { return false; }
108 virtual bool apply_to_weak_ref_discovered_field() { return false; }
109 };
111 // Wrapper closure only used to implement oop_iterate_no_header().
112 class NoHeaderExtendedOopClosure : public ExtendedOopClosure {
113 OopClosure* _wrapped_closure;
114 public:
115 NoHeaderExtendedOopClosure(OopClosure* cl) : _wrapped_closure(cl) {}
116 // Warning: this calls the virtual version do_oop in the the wrapped closure.
117 void do_oop_nv(oop* p) { _wrapped_closure->do_oop(p); }
118 void do_oop_nv(narrowOop* p) { _wrapped_closure->do_oop(p); }
120 void do_oop(oop* p) { assert(false, "Only the _nv versions should be used");
121 _wrapped_closure->do_oop(p); }
122 void do_oop(narrowOop* p) { assert(false, "Only the _nv versions should be used");
123 _wrapped_closure->do_oop(p);}
124 };
126 class KlassClosure : public Closure {
127 public:
128 virtual void do_klass(Klass* k) = 0;
129 };
131 class CLDClosure : public Closure {
132 public:
133 virtual void do_cld(ClassLoaderData* cld) = 0;
134 };
136 class KlassToOopClosure : public KlassClosure {
137 friend class MetadataAwareOopClosure;
138 friend class MetadataAwareOopsInGenClosure;
140 OopClosure* _oop_closure;
142 // Used when _oop_closure couldn't be set in an initialization list.
143 void initialize(OopClosure* oop_closure) {
144 assert(_oop_closure == NULL, "Should only be called once");
145 _oop_closure = oop_closure;
146 }
148 public:
149 KlassToOopClosure(OopClosure* oop_closure = NULL) : _oop_closure(oop_closure) {}
150 virtual void do_klass(Klass* k);
151 };
153 class CLDToOopClosure : public CLDClosure {
154 OopClosure* _oop_closure;
155 KlassToOopClosure _klass_closure;
156 bool _must_claim_cld;
158 public:
159 CLDToOopClosure(OopClosure* oop_closure, bool must_claim_cld = true) :
160 _oop_closure(oop_closure),
161 _klass_closure(oop_closure),
162 _must_claim_cld(must_claim_cld) {}
164 void do_cld(ClassLoaderData* cld);
165 };
167 // The base class for all concurrent marking closures,
168 // that participates in class unloading.
169 // It's used to proxy through the metadata to the oops defined in them.
170 class MetadataAwareOopClosure: public ExtendedOopClosure {
171 KlassToOopClosure _klass_closure;
173 public:
174 MetadataAwareOopClosure() : ExtendedOopClosure() {
175 _klass_closure.initialize(this);
176 }
177 MetadataAwareOopClosure(ReferenceProcessor* rp) : ExtendedOopClosure(rp) {
178 _klass_closure.initialize(this);
179 }
181 virtual bool do_metadata() { return do_metadata_nv(); }
182 inline bool do_metadata_nv() { return true; }
184 virtual void do_klass(Klass* k);
185 void do_klass_nv(Klass* k);
187 virtual void do_class_loader_data(ClassLoaderData* cld);
188 };
190 // ObjectClosure is used for iterating through an object space
192 class ObjectClosure : public Closure {
193 public:
194 // Called for each object.
195 virtual void do_object(oop obj) = 0;
196 };
199 class BoolObjectClosure : public Closure {
200 public:
201 virtual bool do_object_b(oop obj) = 0;
202 };
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 };
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 };
221 // The following are used in CompactibleFreeListSpace and
222 // ConcurrentMarkSweepGeneration.
224 // Blk closure (abstract class)
225 class BlkClosure : public StackObj {
226 public:
227 virtual size_t do_blk(HeapWord* addr) = 0;
228 };
230 // A version of BlkClosure that is expected to be robust
231 // in the face of possibly uninitialized objects.
232 class BlkClosureCareful : public BlkClosure {
233 public:
234 size_t do_blk(HeapWord* addr) {
235 guarantee(false, "call do_blk_careful instead");
236 return 0;
237 }
238 virtual size_t do_blk_careful(HeapWord* addr) = 0;
239 };
241 // SpaceClosure is used for iterating over spaces
243 class Space;
244 class CompactibleSpace;
246 class SpaceClosure : public StackObj {
247 public:
248 // Called for each space
249 virtual void do_space(Space* s) = 0;
250 };
252 class CompactibleSpaceClosure : public StackObj {
253 public:
254 // Called for each compactible space
255 virtual void do_space(CompactibleSpace* s) = 0;
256 };
259 // CodeBlobClosure is used for iterating through code blobs
260 // in the code cache or on thread stacks
262 class CodeBlobClosure : public Closure {
263 public:
264 // Called for each code blob.
265 virtual void do_code_blob(CodeBlob* cb) = 0;
266 };
269 class MarkingCodeBlobClosure : public CodeBlobClosure {
270 public:
271 // Called for each code blob, but at most once per unique blob.
272 virtual void do_newly_marked_nmethod(nmethod* nm) = 0;
274 virtual void do_code_blob(CodeBlob* cb);
275 // = { if (!nmethod(cb)->test_set_oops_do_mark()) do_newly_marked_nmethod(cb); }
277 class MarkScope : public StackObj {
278 protected:
279 bool _active;
280 public:
281 MarkScope(bool activate = true);
282 // = { if (active) nmethod::oops_do_marking_prologue(); }
283 ~MarkScope();
284 // = { if (active) nmethod::oops_do_marking_epilogue(); }
285 };
286 };
289 // Applies an oop closure to all ref fields in code blobs
290 // iterated over in an object iteration.
291 class CodeBlobToOopClosure: public MarkingCodeBlobClosure {
292 OopClosure* _cl;
293 bool _do_marking;
294 public:
295 virtual void do_newly_marked_nmethod(nmethod* cb);
296 // = { cb->oops_do(_cl); }
297 virtual void do_code_blob(CodeBlob* cb);
298 // = { if (_do_marking) super::do_code_blob(cb); else cb->oops_do(_cl); }
299 CodeBlobToOopClosure(OopClosure* cl, bool do_marking)
300 : _cl(cl), _do_marking(do_marking) {}
301 };
305 // MonitorClosure is used for iterating over monitors in the monitors cache
307 class ObjectMonitor;
309 class MonitorClosure : public StackObj {
310 public:
311 // called for each monitor in cache
312 virtual void do_monitor(ObjectMonitor* m) = 0;
313 };
315 // A closure that is applied without any arguments.
316 class VoidClosure : public StackObj {
317 public:
318 // I would have liked to declare this a pure virtual, but that breaks
319 // in mysterious ways, for unknown reasons.
320 virtual void do_void();
321 };
324 // YieldClosure is intended for use by iteration loops
325 // to incrementalize their work, allowing interleaving
326 // of an interruptable task so as to allow other
327 // threads to run (which may not otherwise be able to access
328 // exclusive resources, for instance). Additionally, the
329 // closure also allows for aborting an ongoing iteration
330 // by means of checking the return value from the polling
331 // call.
332 class YieldClosure : public StackObj {
333 public:
334 virtual bool should_return() = 0;
335 };
337 // Abstract closure for serializing data (read or write).
339 class SerializeClosure : public Closure {
340 public:
341 // Return bool indicating whether closure implements read or write.
342 virtual bool reading() const = 0;
344 // Read/write the void pointer pointed to by p.
345 virtual void do_ptr(void** p) = 0;
347 // Read/write the region specified.
348 virtual void do_region(u_char* start, size_t size) = 0;
350 // Check/write the tag. If reading, then compare the tag against
351 // the passed in value and fail is they don't match. This allows
352 // for verification that sections of the serialized data are of the
353 // correct length.
354 virtual void do_tag(int tag) = 0;
355 };
357 class SymbolClosure : public StackObj {
358 public:
359 virtual void do_symbol(Symbol**) = 0;
361 // Clear LSB in symbol address; it can be set by CPSlot.
362 static Symbol* load_symbol(Symbol** p) {
363 return (Symbol*)(intptr_t(*p) & ~1);
364 }
366 // Store symbol, adjusting new pointer if the original pointer was adjusted
367 // (symbol references in constant pool slots have their LSB set to 1).
368 static void store_symbol(Symbol** p, Symbol* sym) {
369 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1));
370 }
371 };
374 // Helper defines for ExtendOopClosure
376 #define if_do_metadata_checked(closure, nv_suffix) \
377 /* Make sure the non-virtual and the virtual versions match. */ \
378 assert(closure->do_metadata##nv_suffix() == closure->do_metadata(), \
379 "Inconsistency in do_metadata"); \
380 if (closure->do_metadata##nv_suffix())
382 #define assert_should_ignore_metadata(closure, nv_suffix) \
383 assert(!closure->do_metadata##nv_suffix(), "Code to handle metadata is not implemented")
385 #endif // SHARE_VM_MEMORY_ITERATOR_HPP