1 /* 2 * Copyright (c) 1997, 2013, 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_VM_MEMORY_ITERATOR_HPP 26 #define SHARE_VM_MEMORY_ITERATOR_HPP 27 28 #include "memory/allocation.hpp" 29 #include "memory/memRegion.hpp" 30 #include "utilities/top.hpp" 31 32 class CodeBlob; 33 class nmethod; 34 class ReferenceProcessor; 35 class DataLayout; 36 class KlassClosure; 37 class ClassLoaderData; 38 39 // The following classes are C++ `closures` for iterating over objects, roots and spaces 40 41 class Closure : public StackObj { }; 42 43 // OopClosure is used for iterating through references to Java objects. 44 class OopClosure : public Closure { 45 public: 46 virtual void do_oop(oop* o) = 0; 47 virtual void do_oop_v(oop* o) { do_oop(o); } 48 virtual void do_oop(narrowOop* o) = 0; 49 virtual void do_oop_v(narrowOop* o) { do_oop(o); } 50 }; 51 52 // ExtendedOopClosure adds extra code to be run during oop iterations. 53 // This is needed by the GC and is extracted to a separate type to not 54 // pollute the OopClosure interface. 55 class ExtendedOopClosure : public OopClosure { 56 public: 57 ReferenceProcessor* _ref_processor; 58 ExtendedOopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { } 59 ExtendedOopClosure() : OopClosure(), _ref_processor(NULL) { } 60 61 // If the do_metadata functions return "true", 62 // we invoke the following when running oop_iterate(): 63 // 64 // 1) do_klass on the header klass pointer. 65 // 2) do_klass on the klass pointer in the mirrors. 66 // 3) do_class_loader_data on the class loader data in class loaders. 67 // 68 // The virtual (without suffix) and the non-virtual (with _nv suffix) need 69 // to be updated together, or else the devirtualization will break. 70 // 71 // Providing default implementations of the _nv functions unfortunately 72 // removes the compile-time safeness, but reduces the clutter for the 73 // ExtendedOopClosures that don't need to walk the metadata. Currently, 74 // only CMS needs these. 75 76 virtual bool do_metadata() { return do_metadata_nv(); } 77 bool do_metadata_v() { return do_metadata(); } 78 bool do_metadata_nv() { return false; } 79 80 virtual void do_klass(Klass* k) { do_klass_nv(k); } 81 void do_klass_v(Klass* k) { do_klass(k); } 82 void do_klass_nv(Klass* k) { ShouldNotReachHere(); } 83 84 virtual void do_class_loader_data(ClassLoaderData* cld) { ShouldNotReachHere(); } 85 86 // True iff this closure may be safely applied more than once to an oop 87 // location without an intervening "major reset" (like the end of a GC). 88 virtual bool idempotent() { return false; } 89 virtual bool apply_to_weak_ref_discovered_field() { return false; } 90 }; 91 92 // Wrapper closure only used to implement oop_iterate_no_header(). 93 class NoHeaderExtendedOopClosure : public ExtendedOopClosure { 94 OopClosure* _wrapped_closure; 95 public: 96 NoHeaderExtendedOopClosure(OopClosure* cl) : _wrapped_closure(cl) {} 97 // Warning: this calls the virtual version do_oop in the the wrapped closure. 98 void do_oop_nv(oop* p) { _wrapped_closure->do_oop(p); } 99 void do_oop_nv(narrowOop* p) { _wrapped_closure->do_oop(p); } 100 101 void do_oop(oop* p) { assert(false, "Only the _nv versions should be used"); 102 _wrapped_closure->do_oop(p); } 103 void do_oop(narrowOop* p) { assert(false, "Only the _nv versions should be used"); 104 _wrapped_closure->do_oop(p);} 105 }; 106 107 class KlassClosure : public Closure { 108 public: 109 virtual void do_klass(Klass* k) = 0; 110 }; 111 112 class CLDClosure : public Closure { 113 public: 114 virtual void do_cld(ClassLoaderData* cld) = 0; 115 }; 116 117 class KlassToOopClosure : public KlassClosure { 118 friend class MetadataAwareOopClosure; 119 friend class MetadataAwareOopsInGenClosure; 120 121 OopClosure* _oop_closure; 122 123 // Used when _oop_closure couldn't be set in an initialization list. 124 void initialize(OopClosure* oop_closure) { 125 assert(_oop_closure == NULL, "Should only be called once"); 126 _oop_closure = oop_closure; 127 } 128 129 public: 130 KlassToOopClosure(OopClosure* oop_closure = NULL) : _oop_closure(oop_closure) {} 131 virtual void do_klass(Klass* k); 132 }; 133 134 class CLDToOopClosure : public CLDClosure { 135 OopClosure* _oop_closure; 136 KlassToOopClosure _klass_closure; 137 bool _must_claim_cld; 138 139 public: 140 CLDToOopClosure(OopClosure* oop_closure, bool must_claim_cld = true) : 141 _oop_closure(oop_closure), 142 _klass_closure(oop_closure), 143 _must_claim_cld(must_claim_cld) {} 144 145 void do_cld(ClassLoaderData* cld); 146 }; 147 148 // The base class for all concurrent marking closures, 149 // that participates in class unloading. 150 // It's used to proxy through the metadata to the oops defined in them. 151 class MetadataAwareOopClosure: public ExtendedOopClosure { 152 KlassToOopClosure _klass_closure; 153 154 public: 155 MetadataAwareOopClosure() : ExtendedOopClosure() { 156 _klass_closure.initialize(this); 157 } 158 MetadataAwareOopClosure(ReferenceProcessor* rp) : ExtendedOopClosure(rp) { 159 _klass_closure.initialize(this); 160 } 161 162 virtual bool do_metadata() { return do_metadata_nv(); } 163 inline bool do_metadata_nv() { return true; } 164 165 virtual void do_klass(Klass* k); 166 void do_klass_nv(Klass* k); 167 168 virtual void do_class_loader_data(ClassLoaderData* cld); 169 }; 170 171 // ObjectClosure is used for iterating through an object space 172 173 class ObjectClosure : public Closure { 174 public: 175 // Called for each object. 176 virtual void do_object(oop obj) = 0; 177 }; 178 179 180 class BoolObjectClosure : public Closure { 181 public: 182 virtual bool do_object_b(oop obj) = 0; 183 }; 184 185 // Applies an oop closure to all ref fields in objects iterated over in an 186 // object iteration. 187 class ObjectToOopClosure: public ObjectClosure { 188 ExtendedOopClosure* _cl; 189 public: 190 void do_object(oop obj); 191 ObjectToOopClosure(ExtendedOopClosure* cl) : _cl(cl) {} 192 }; 193 194 // A version of ObjectClosure that is expected to be robust 195 // in the face of possibly uninitialized objects. 196 class ObjectClosureCareful : public ObjectClosure { 197 public: 198 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0; 199 virtual size_t do_object_careful(oop p) = 0; 200 }; 201 202 // The following are used in CompactibleFreeListSpace and 203 // ConcurrentMarkSweepGeneration. 204 205 // Blk closure (abstract class) 206 class BlkClosure : public StackObj { 207 public: 208 virtual size_t do_blk(HeapWord* addr) = 0; 209 }; 210 211 // A version of BlkClosure that is expected to be robust 212 // in the face of possibly uninitialized objects. 213 class BlkClosureCareful : public BlkClosure { 214 public: 215 size_t do_blk(HeapWord* addr) { 216 guarantee(false, "call do_blk_careful instead"); 217 return 0; 218 } 219 virtual size_t do_blk_careful(HeapWord* addr) = 0; 220 }; 221 222 // SpaceClosure is used for iterating over spaces 223 224 class Space; 225 class CompactibleSpace; 226 227 class SpaceClosure : public StackObj { 228 public: 229 // Called for each space 230 virtual void do_space(Space* s) = 0; 231 }; 232 233 class CompactibleSpaceClosure : public StackObj { 234 public: 235 // Called for each compactible space 236 virtual void do_space(CompactibleSpace* s) = 0; 237 }; 238 239 240 // CodeBlobClosure is used for iterating through code blobs 241 // in the code cache or on thread stacks 242 243 class CodeBlobClosure : public Closure { 244 public: 245 // Called for each code blob. 246 virtual void do_code_blob(CodeBlob* cb) = 0; 247 }; 248 249 250 class MarkingCodeBlobClosure : public CodeBlobClosure { 251 public: 252 // Called for each code blob, but at most once per unique blob. 253 virtual void do_newly_marked_nmethod(nmethod* nm) = 0; 254 255 virtual void do_code_blob(CodeBlob* cb); 256 // = { if (!nmethod(cb)->test_set_oops_do_mark()) do_newly_marked_nmethod(cb); } 257 258 class MarkScope : public StackObj { 259 protected: 260 bool _active; 261 public: 262 MarkScope(bool activate = true); 263 // = { if (active) nmethod::oops_do_marking_prologue(); } 264 ~MarkScope(); 265 // = { if (active) nmethod::oops_do_marking_epilogue(); } 266 }; 267 }; 268 269 270 // Applies an oop closure to all ref fields in code blobs 271 // iterated over in an object iteration. 272 class CodeBlobToOopClosure: public MarkingCodeBlobClosure { 273 OopClosure* _cl; 274 bool _do_marking; 275 public: 276 virtual void do_newly_marked_nmethod(nmethod* cb); 277 // = { cb->oops_do(_cl); } 278 virtual void do_code_blob(CodeBlob* cb); 279 // = { if (_do_marking) super::do_code_blob(cb); else cb->oops_do(_cl); } 280 CodeBlobToOopClosure(OopClosure* cl, bool do_marking) 281 : _cl(cl), _do_marking(do_marking) {} 282 }; 283 284 285 286 // MonitorClosure is used for iterating over monitors in the monitors cache 287 288 class ObjectMonitor; 289 290 class MonitorClosure : public StackObj { 291 public: 292 // called for each monitor in cache 293 virtual void do_monitor(ObjectMonitor* m) = 0; 294 }; 295 296 // A closure that is applied without any arguments. 297 class VoidClosure : public StackObj { 298 public: 299 // I would have liked to declare this a pure virtual, but that breaks 300 // in mysterious ways, for unknown reasons. 301 virtual void do_void(); 302 }; 303 304 305 // YieldClosure is intended for use by iteration loops 306 // to incrementalize their work, allowing interleaving 307 // of an interruptable task so as to allow other 308 // threads to run (which may not otherwise be able to access 309 // exclusive resources, for instance). Additionally, the 310 // closure also allows for aborting an ongoing iteration 311 // by means of checking the return value from the polling 312 // call. 313 class YieldClosure : public StackObj { 314 public: 315 virtual bool should_return() = 0; 316 }; 317 318 // Abstract closure for serializing data (read or write). 319 320 class SerializeClosure : public Closure { 321 public: 322 // Return bool indicating whether closure implements read or write. 323 virtual bool reading() const = 0; 324 325 // Read/write the void pointer pointed to by p. 326 virtual void do_ptr(void** p) = 0; 327 328 // Read/write the region specified. 329 virtual void do_region(u_char* start, size_t size) = 0; 330 331 // Check/write the tag. If reading, then compare the tag against 332 // the passed in value and fail is they don't match. This allows 333 // for verification that sections of the serialized data are of the 334 // correct length. 335 virtual void do_tag(int tag) = 0; 336 }; 337 338 class SymbolClosure : public StackObj { 339 public: 340 virtual void do_symbol(Symbol**) = 0; 341 342 // Clear LSB in symbol address; it can be set by CPSlot. 343 static Symbol* load_symbol(Symbol** p) { 344 return (Symbol*)(intptr_t(*p) & ~1); 345 } 346 347 // Store symbol, adjusting new pointer if the original pointer was adjusted 348 // (symbol references in constant pool slots have their LSB set to 1). 349 static void store_symbol(Symbol** p, Symbol* sym) { 350 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1)); 351 } 352 }; 353 354 355 // Helper defines for ExtendOopClosure 356 357 #define if_do_metadata_checked(closure, nv_suffix) \ 358 /* Make sure the non-virtual and the virtual versions match. */ \ 359 assert(closure->do_metadata##nv_suffix() == closure->do_metadata(), \ 360 "Inconsistency in do_metadata"); \ 361 if (closure->do_metadata##nv_suffix()) 362 363 #define assert_should_ignore_metadata(closure, nv_suffix) \ 364 assert(!closure->do_metadata##nv_suffix(), "Code to handle metadata is not implemented") 365 366 #endif // SHARE_VM_MEMORY_ITERATOR_HPP