1 /* 2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_MEMORY_ITERATOR_HPP 26 #define SHARE_MEMORY_ITERATOR_HPP 27 28 #include "memory/allocation.hpp" 29 #include "memory/memRegion.hpp" 30 #include "oops/oopsHierarchy.hpp" 31 32 class CodeBlob; 33 class nmethod; 34 class ReferenceDiscoverer; 35 class DataLayout; 36 class KlassClosure; 37 class ClassLoaderData; 38 class Symbol; 39 class Metadata; 40 class Thread; 41 42 // The following classes are C++ `closures` for iterating over objects, roots and spaces 43 44 class Closure : public StackObj { }; 45 46 // Thread iterator 47 class ThreadClosure: public Closure { 48 public: 49 virtual void do_thread(Thread* thread) = 0; 50 }; 51 52 // OopClosure is used for iterating through references to Java objects. 53 class OopClosure : public Closure { 54 public: 55 virtual void do_oop(oop* o) = 0; 56 virtual void do_oop(narrowOop* o) = 0; 57 }; 58 59 class DoNothingClosure : public OopClosure { 60 public: do_oop(oop * p)61 virtual void do_oop(oop* p) {} do_oop(narrowOop * p)62 virtual void do_oop(narrowOop* p) {} 63 }; 64 extern DoNothingClosure do_nothing_cl; 65 66 // OopIterateClosure 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 OopIterateClosure : public OopClosure { 70 private: 71 ReferenceDiscoverer* _ref_discoverer; 72 73 protected: OopIterateClosure(ReferenceDiscoverer * rd)74 OopIterateClosure(ReferenceDiscoverer* rd) : _ref_discoverer(rd) { } OopIterateClosure()75 OopIterateClosure() : _ref_discoverer(NULL) { } ~OopIterateClosure()76 ~OopIterateClosure() { } 77 set_ref_discoverer_internal(ReferenceDiscoverer * rd)78 void set_ref_discoverer_internal(ReferenceDiscoverer* rd) { _ref_discoverer = rd; } 79 80 public: ref_discoverer() const81 ReferenceDiscoverer* ref_discoverer() const { return _ref_discoverer; } 82 83 // Iteration of InstanceRefKlasses differ depending on the closure, 84 // the below enum describes the different alternatives. 85 enum ReferenceIterationMode { 86 DO_DISCOVERY, // Apply closure and discover references 87 DO_DISCOVERED_AND_DISCOVERY, // Apply closure to discovered field and do discovery 88 DO_FIELDS, // Apply closure to all fields 89 DO_FIELDS_EXCEPT_REFERENT // Apply closure to all fields except the referent field 90 }; 91 92 // The default iteration mode is to do discovery. reference_iteration_mode()93 virtual ReferenceIterationMode reference_iteration_mode() { return DO_DISCOVERY; } 94 95 // If the do_metadata functions return "true", 96 // we invoke the following when running oop_iterate(): 97 // 98 // 1) do_klass on the header klass pointer. 99 // 2) do_klass on the klass pointer in the mirrors. 100 // 3) do_cld on the class loader data in class loaders. 101 102 virtual bool do_metadata() = 0; 103 virtual void do_klass(Klass* k) = 0; 104 virtual void do_cld(ClassLoaderData* cld) = 0; 105 106 #ifdef ASSERT 107 // Default verification of each visited oop field. 108 template <typename T> void verify(T* p); 109 110 // Can be used by subclasses to turn off the default verification of oop fields. should_verify_oops()111 virtual bool should_verify_oops() { return true; } 112 #endif 113 }; 114 115 // An OopIterateClosure that can be used when there's no need to visit the Metadata. 116 class BasicOopIterateClosure : public OopIterateClosure { 117 public: BasicOopIterateClosure(ReferenceDiscoverer * rd=NULL)118 BasicOopIterateClosure(ReferenceDiscoverer* rd = NULL) : OopIterateClosure(rd) {} 119 do_metadata()120 virtual bool do_metadata() { return false; } do_klass(Klass * k)121 virtual void do_klass(Klass* k) { ShouldNotReachHere(); } do_cld(ClassLoaderData * cld)122 virtual void do_cld(ClassLoaderData* cld) { ShouldNotReachHere(); } 123 }; 124 125 class KlassClosure : public Closure { 126 public: 127 virtual void do_klass(Klass* k) = 0; 128 }; 129 130 class CLDClosure : public Closure { 131 public: 132 virtual void do_cld(ClassLoaderData* cld) = 0; 133 }; 134 135 class MetadataClosure : public Closure { 136 public: 137 virtual void do_metadata(Metadata* md) = 0; 138 }; 139 140 141 class CLDToOopClosure : public CLDClosure { 142 OopClosure* _oop_closure; 143 int _cld_claim; 144 145 public: CLDToOopClosure(OopClosure * oop_closure,int cld_claim)146 CLDToOopClosure(OopClosure* oop_closure, 147 int cld_claim) : 148 _oop_closure(oop_closure), 149 _cld_claim(cld_claim) {} 150 151 void do_cld(ClassLoaderData* cld); 152 }; 153 154 class ClaimMetadataVisitingOopIterateClosure : public OopIterateClosure { 155 protected: 156 const int _claim; 157 158 public: ClaimMetadataVisitingOopIterateClosure(int claim,ReferenceDiscoverer * rd=NULL)159 ClaimMetadataVisitingOopIterateClosure(int claim, ReferenceDiscoverer* rd = NULL) : 160 OopIterateClosure(rd), 161 _claim(claim) { } 162 do_metadata()163 virtual bool do_metadata() { return true; } 164 virtual void do_klass(Klass* k); 165 virtual void do_cld(ClassLoaderData* cld); 166 }; 167 168 // The base class for all concurrent marking closures, 169 // that participates in class unloading. 170 // It's used to proxy through the metadata to the oops defined in them. 171 class MetadataVisitingOopIterateClosure: public ClaimMetadataVisitingOopIterateClosure { 172 public: 173 MetadataVisitingOopIterateClosure(ReferenceDiscoverer* rd = NULL); 174 }; 175 176 // ObjectClosure is used for iterating through an object space 177 178 class ObjectClosure : public Closure { 179 public: 180 // Called for each object. 181 virtual void do_object(oop obj) = 0; 182 }; 183 184 185 class BoolObjectClosure : public Closure { 186 public: 187 virtual bool do_object_b(oop obj) = 0; 188 }; 189 190 class AlwaysTrueClosure: public BoolObjectClosure { 191 public: do_object_b(oop p)192 bool do_object_b(oop p) { return true; } 193 }; 194 195 class AlwaysFalseClosure : public BoolObjectClosure { 196 public: do_object_b(oop p)197 bool do_object_b(oop p) { return false; } 198 }; 199 200 // Applies an oop closure to all ref fields in objects iterated over in an 201 // object iteration. 202 class ObjectToOopClosure: public ObjectClosure { 203 OopIterateClosure* _cl; 204 public: 205 void do_object(oop obj); ObjectToOopClosure(OopIterateClosure * cl)206 ObjectToOopClosure(OopIterateClosure* cl) : _cl(cl) {} 207 }; 208 209 // SpaceClosure is used for iterating over spaces 210 211 class Space; 212 class CompactibleSpace; 213 214 class SpaceClosure : public StackObj { 215 public: 216 // Called for each space 217 virtual void do_space(Space* s) = 0; 218 }; 219 220 class CompactibleSpaceClosure : public StackObj { 221 public: 222 // Called for each compactible space 223 virtual void do_space(CompactibleSpace* s) = 0; 224 }; 225 226 227 // CodeBlobClosure is used for iterating through code blobs 228 // in the code cache or on thread stacks 229 230 class CodeBlobClosure : public Closure { 231 public: 232 // Called for each code blob. 233 virtual void do_code_blob(CodeBlob* cb) = 0; 234 }; 235 236 // Applies an oop closure to all ref fields in code blobs 237 // iterated over in an object iteration. 238 class CodeBlobToOopClosure : public CodeBlobClosure { 239 OopClosure* _cl; 240 bool _fix_relocations; 241 protected: 242 void do_nmethod(nmethod* nm); 243 public: 244 // If fix_relocations(), then cl must copy objects to their new location immediately to avoid 245 // patching nmethods with the old locations. CodeBlobToOopClosure(OopClosure * cl,bool fix_relocations)246 CodeBlobToOopClosure(OopClosure* cl, bool fix_relocations) : _cl(cl), _fix_relocations(fix_relocations) {} 247 virtual void do_code_blob(CodeBlob* cb); 248 fix_relocations() const249 bool fix_relocations() const { return _fix_relocations; } 250 const static bool FixRelocations = true; 251 }; 252 253 class MarkingCodeBlobClosure : public CodeBlobToOopClosure { 254 public: MarkingCodeBlobClosure(OopClosure * cl,bool fix_relocations)255 MarkingCodeBlobClosure(OopClosure* cl, bool fix_relocations) : CodeBlobToOopClosure(cl, fix_relocations) {} 256 // Called for each code blob, but at most once per unique blob. 257 258 virtual void do_code_blob(CodeBlob* cb); 259 }; 260 261 class NMethodClosure : public Closure { 262 public: 263 virtual void do_nmethod(nmethod* n) = 0; 264 }; 265 266 // MonitorClosure is used for iterating over monitors in the monitors cache 267 268 class ObjectMonitor; 269 270 class MonitorClosure : public StackObj { 271 public: 272 // called for each monitor in cache 273 virtual void do_monitor(ObjectMonitor* m) = 0; 274 }; 275 276 // A closure that is applied without any arguments. 277 class VoidClosure : public StackObj { 278 public: 279 // I would have liked to declare this a pure virtual, but that breaks 280 // in mysterious ways, for unknown reasons. 281 virtual void do_void(); 282 }; 283 284 285 // YieldClosure is intended for use by iteration loops 286 // to incrementalize their work, allowing interleaving 287 // of an interruptable task so as to allow other 288 // threads to run (which may not otherwise be able to access 289 // exclusive resources, for instance). Additionally, the 290 // closure also allows for aborting an ongoing iteration 291 // by means of checking the return value from the polling 292 // call. 293 class YieldClosure : public StackObj { 294 public: 295 virtual bool should_return() = 0; 296 297 // Yield on a fine-grain level. The check in case of not yielding should be very fast. should_return_fine_grain()298 virtual bool should_return_fine_grain() { return false; } 299 }; 300 301 // Abstract closure for serializing data (read or write). 302 303 class SerializeClosure : public Closure { 304 public: 305 // Return bool indicating whether closure implements read or write. 306 virtual bool reading() const = 0; 307 308 // Read/write the void pointer pointed to by p. 309 virtual void do_ptr(void** p) = 0; 310 311 // Read/write the 32-bit unsigned integer pointed to by p. 312 virtual void do_u4(u4* p) = 0; 313 314 // Read/write the bool pointed to by p. 315 virtual void do_bool(bool* p) = 0; 316 317 // Read/write the region specified. 318 virtual void do_region(u_char* start, size_t size) = 0; 319 320 // Check/write the tag. If reading, then compare the tag against 321 // the passed in value and fail is they don't match. This allows 322 // for verification that sections of the serialized data are of the 323 // correct length. 324 virtual void do_tag(int tag) = 0; 325 326 // Read/write the oop 327 virtual void do_oop(oop* o) = 0; 328 writing()329 bool writing() { 330 return !reading(); 331 } 332 }; 333 334 class SymbolClosure : public StackObj { 335 public: 336 virtual void do_symbol(Symbol**) = 0; 337 338 // Clear LSB in symbol address; it can be set by CPSlot. load_symbol(Symbol ** p)339 static Symbol* load_symbol(Symbol** p) { 340 return (Symbol*)(intptr_t(*p) & ~1); 341 } 342 343 // Store symbol, adjusting new pointer if the original pointer was adjusted 344 // (symbol references in constant pool slots have their LSB set to 1). store_symbol(Symbol ** p,Symbol * sym)345 static void store_symbol(Symbol** p, Symbol* sym) { 346 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1)); 347 } 348 }; 349 350 // Dispatches to the non-virtual functions if OopClosureType has 351 // a concrete implementation, otherwise a virtual call is taken. 352 class Devirtualizer { 353 public: 354 template <typename OopClosureType, typename T> static void do_oop_no_verify(OopClosureType* closure, T* p); 355 template <typename OopClosureType, typename T> static void do_oop(OopClosureType* closure, T* p); 356 template <typename OopClosureType> static void do_klass(OopClosureType* closure, Klass* k); 357 template <typename OopClosureType> static void do_cld(OopClosureType* closure, ClassLoaderData* cld); 358 template <typename OopClosureType> static bool do_metadata(OopClosureType* closure); 359 }; 360 361 class OopIteratorClosureDispatch { 362 public: 363 template <typename OopClosureType> static void oop_oop_iterate(OopClosureType* cl, oop obj, Klass* klass); 364 template <typename OopClosureType> static void oop_oop_iterate(OopClosureType* cl, oop obj, Klass* klass, MemRegion mr); 365 template <typename OopClosureType> static void oop_oop_iterate_backwards(OopClosureType* cl, oop obj, Klass* klass); 366 }; 367 368 #endif // SHARE_MEMORY_ITERATOR_HPP 369