jvmtiTagMap.cpp revision 1472:c18cbe5936b8
1/* 2 * Copyright (c) 2003, 2009, 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# include "incls/_precompiled.incl" 26# include "incls/_jvmtiTagMap.cpp.incl" 27 28// JvmtiTagHashmapEntry 29// 30// Each entry encapsulates a JNI weak reference to the tagged object 31// and the tag value. In addition an entry includes a next pointer which 32// is used to chain entries together. 33 34class JvmtiTagHashmapEntry : public CHeapObj { 35 private: 36 friend class JvmtiTagMap; 37 38 jweak _object; // JNI weak ref to tagged object 39 jlong _tag; // the tag 40 JvmtiTagHashmapEntry* _next; // next on the list 41 42 inline void init(jweak object, jlong tag) { 43 _object = object; 44 _tag = tag; 45 _next = NULL; 46 } 47 48 // constructor 49 JvmtiTagHashmapEntry(jweak object, jlong tag) { init(object, tag); } 50 51 public: 52 53 // accessor methods 54 inline jweak object() const { return _object; } 55 inline jlong tag() const { return _tag; } 56 57 inline void set_tag(jlong tag) { 58 assert(tag != 0, "can't be zero"); 59 _tag = tag; 60 } 61 62 inline JvmtiTagHashmapEntry* next() const { return _next; } 63 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; } 64}; 65 66 67// JvmtiTagHashmap 68// 69// A hashmap is essentially a table of pointers to entries. Entries 70// are hashed to a location, or position in the table, and then 71// chained from that location. The "key" for hashing is address of 72// the object, or oop. The "value" is the JNI weak reference to the 73// object and the tag value. Keys are not stored with the entry. 74// Instead the weak reference is resolved to obtain the key. 75// 76// A hashmap maintains a count of the number entries in the hashmap 77// and resizes if the number of entries exceeds a given threshold. 78// The threshold is specified as a percentage of the size - for 79// example a threshold of 0.75 will trigger the hashmap to resize 80// if the number of entries is >75% of table size. 81// 82// A hashmap provides functions for adding, removing, and finding 83// entries. It also provides a function to iterate over all entries 84// in the hashmap. 85 86class JvmtiTagHashmap : public CHeapObj { 87 private: 88 friend class JvmtiTagMap; 89 90 enum { 91 small_trace_threshold = 10000, // threshold for tracing 92 medium_trace_threshold = 100000, 93 large_trace_threshold = 1000000, 94 initial_trace_threshold = small_trace_threshold 95 }; 96 97 static int _sizes[]; // array of possible hashmap sizes 98 int _size; // actual size of the table 99 int _size_index; // index into size table 100 101 int _entry_count; // number of entries in the hashmap 102 103 float _load_factor; // load factor as a % of the size 104 int _resize_threshold; // computed threshold to trigger resizing. 105 bool _resizing_enabled; // indicates if hashmap can resize 106 107 int _trace_threshold; // threshold for trace messages 108 109 JvmtiTagHashmapEntry** _table; // the table of entries. 110 111 // private accessors 112 int resize_threshold() const { return _resize_threshold; } 113 int trace_threshold() const { return _trace_threshold; } 114 115 // initialize the hashmap 116 void init(int size_index=0, float load_factor=4.0f) { 117 int initial_size = _sizes[size_index]; 118 _size_index = size_index; 119 _size = initial_size; 120 _entry_count = 0; 121 if (TraceJVMTIObjectTagging) { 122 _trace_threshold = initial_trace_threshold; 123 } else { 124 _trace_threshold = -1; 125 } 126 _load_factor = load_factor; 127 _resize_threshold = (int)(_load_factor * _size); 128 _resizing_enabled = true; 129 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*); 130 _table = (JvmtiTagHashmapEntry**)os::malloc(s); 131 if (_table == NULL) { 132 vm_exit_out_of_memory(s, "unable to allocate initial hashtable for jvmti object tags"); 133 } 134 for (int i=0; i<initial_size; i++) { 135 _table[i] = NULL; 136 } 137 } 138 139 // hash a given key (oop) with the specified size 140 static unsigned int hash(oop key, int size) { 141 // shift right to get better distribution (as these bits will be zero 142 // with aligned addresses) 143 unsigned int addr = (unsigned int)((intptr_t)key); 144#ifdef _LP64 145 return (addr >> 3) % size; 146#else 147 return (addr >> 2) % size; 148#endif 149 } 150 151 // hash a given key (oop) 152 unsigned int hash(oop key) { 153 return hash(key, _size); 154 } 155 156 // resize the hashmap - allocates a large table and re-hashes 157 // all entries into the new table. 158 void resize() { 159 int new_size_index = _size_index+1; 160 int new_size = _sizes[new_size_index]; 161 if (new_size < 0) { 162 // hashmap already at maximum capacity 163 return; 164 } 165 166 // allocate new table 167 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*); 168 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s); 169 if (new_table == NULL) { 170 warning("unable to allocate larger hashtable for jvmti object tags"); 171 set_resizing_enabled(false); 172 return; 173 } 174 175 // initialize new table 176 int i; 177 for (i=0; i<new_size; i++) { 178 new_table[i] = NULL; 179 } 180 181 // rehash all entries into the new table 182 for (i=0; i<_size; i++) { 183 JvmtiTagHashmapEntry* entry = _table[i]; 184 while (entry != NULL) { 185 JvmtiTagHashmapEntry* next = entry->next(); 186 oop key = JNIHandles::resolve(entry->object()); 187 assert(key != NULL, "jni weak reference cleared!!"); 188 unsigned int h = hash(key, new_size); 189 JvmtiTagHashmapEntry* anchor = new_table[h]; 190 if (anchor == NULL) { 191 new_table[h] = entry; 192 entry->set_next(NULL); 193 } else { 194 entry->set_next(anchor); 195 new_table[h] = entry; 196 } 197 entry = next; 198 } 199 } 200 201 // free old table and update settings. 202 os::free((void*)_table); 203 _table = new_table; 204 _size_index = new_size_index; 205 _size = new_size; 206 207 // compute new resize threshold 208 _resize_threshold = (int)(_load_factor * _size); 209 } 210 211 212 // internal remove function - remove an entry at a given position in the 213 // table. 214 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) { 215 assert(pos >= 0 && pos < _size, "out of range"); 216 if (prev == NULL) { 217 _table[pos] = entry->next(); 218 } else { 219 prev->set_next(entry->next()); 220 } 221 assert(_entry_count > 0, "checking"); 222 _entry_count--; 223 } 224 225 // resizing switch 226 bool is_resizing_enabled() const { return _resizing_enabled; } 227 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; } 228 229 // debugging 230 void print_memory_usage(); 231 void compute_next_trace_threshold(); 232 233 public: 234 235 // create a JvmtiTagHashmap of a preferred size and optionally a load factor. 236 // The preferred size is rounded down to an actual size. 237 JvmtiTagHashmap(int size, float load_factor=0.0f) { 238 int i=0; 239 while (_sizes[i] < size) { 240 if (_sizes[i] < 0) { 241 assert(i > 0, "sanity check"); 242 i--; 243 break; 244 } 245 i++; 246 } 247 248 // if a load factor is specified then use it, otherwise use default 249 if (load_factor > 0.01f) { 250 init(i, load_factor); 251 } else { 252 init(i); 253 } 254 } 255 256 // create a JvmtiTagHashmap with default settings 257 JvmtiTagHashmap() { 258 init(); 259 } 260 261 // release table when JvmtiTagHashmap destroyed 262 ~JvmtiTagHashmap() { 263 if (_table != NULL) { 264 os::free((void*)_table); 265 _table = NULL; 266 } 267 } 268 269 // accessors 270 int size() const { return _size; } 271 JvmtiTagHashmapEntry** table() const { return _table; } 272 int entry_count() const { return _entry_count; } 273 274 // find an entry in the hashmap, returns NULL if not found. 275 inline JvmtiTagHashmapEntry* find(oop key) { 276 unsigned int h = hash(key); 277 JvmtiTagHashmapEntry* entry = _table[h]; 278 while (entry != NULL) { 279 oop orig_key = JNIHandles::resolve(entry->object()); 280 assert(orig_key != NULL, "jni weak reference cleared!!"); 281 if (key == orig_key) { 282 break; 283 } 284 entry = entry->next(); 285 } 286 return entry; 287 } 288 289 290 // add a new entry to hashmap 291 inline void add(oop key, JvmtiTagHashmapEntry* entry) { 292 assert(key != NULL, "checking"); 293 assert(find(key) == NULL, "duplicate detected"); 294 unsigned int h = hash(key); 295 JvmtiTagHashmapEntry* anchor = _table[h]; 296 if (anchor == NULL) { 297 _table[h] = entry; 298 entry->set_next(NULL); 299 } else { 300 entry->set_next(anchor); 301 _table[h] = entry; 302 } 303 304 _entry_count++; 305 if (trace_threshold() > 0 && entry_count() >= trace_threshold()) { 306 assert(TraceJVMTIObjectTagging, "should only get here when tracing"); 307 print_memory_usage(); 308 compute_next_trace_threshold(); 309 } 310 311 // if the number of entries exceed the threshold then resize 312 if (entry_count() > resize_threshold() && is_resizing_enabled()) { 313 resize(); 314 } 315 } 316 317 // remove an entry with the given key. 318 inline JvmtiTagHashmapEntry* remove(oop key) { 319 unsigned int h = hash(key); 320 JvmtiTagHashmapEntry* entry = _table[h]; 321 JvmtiTagHashmapEntry* prev = NULL; 322 while (entry != NULL) { 323 oop orig_key = JNIHandles::resolve(entry->object()); 324 assert(orig_key != NULL, "jni weak reference cleared!!"); 325 if (key == orig_key) { 326 break; 327 } 328 prev = entry; 329 entry = entry->next(); 330 } 331 if (entry != NULL) { 332 remove(prev, h, entry); 333 } 334 return entry; 335 } 336 337 // iterate over all entries in the hashmap 338 void entry_iterate(JvmtiTagHashmapEntryClosure* closure); 339}; 340 341// possible hashmap sizes - odd primes that roughly double in size. 342// To avoid excessive resizing the odd primes from 4801-76831 and 343// 76831-307261 have been removed. The list must be terminated by -1. 344int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891, 345 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 }; 346 347 348// A supporting class for iterating over all entries in Hashmap 349class JvmtiTagHashmapEntryClosure { 350 public: 351 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0; 352}; 353 354 355// iterate over all entries in the hashmap 356void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) { 357 for (int i=0; i<_size; i++) { 358 JvmtiTagHashmapEntry* entry = _table[i]; 359 JvmtiTagHashmapEntry* prev = NULL; 360 while (entry != NULL) { 361 // obtain the next entry before invoking do_entry - this is 362 // necessary because do_entry may remove the entry from the 363 // hashmap. 364 JvmtiTagHashmapEntry* next = entry->next(); 365 closure->do_entry(entry); 366 entry = next; 367 } 368 } 369} 370 371// debugging 372void JvmtiTagHashmap::print_memory_usage() { 373 intptr_t p = (intptr_t)this; 374 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p); 375 376 // table + entries in KB 377 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) + 378 entry_count()*sizeof(JvmtiTagHashmapEntry))/K; 379 380 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K); 381 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]", 382 entry_count(), hashmap_usage, weak_globals_usage); 383} 384 385// compute threshold for the next trace message 386void JvmtiTagHashmap::compute_next_trace_threshold() { 387 if (trace_threshold() < medium_trace_threshold) { 388 _trace_threshold += small_trace_threshold; 389 } else { 390 if (trace_threshold() < large_trace_threshold) { 391 _trace_threshold += medium_trace_threshold; 392 } else { 393 _trace_threshold += large_trace_threshold; 394 } 395 } 396} 397 398// memory region for young generation 399MemRegion JvmtiTagMap::_young_gen; 400 401// get the memory region used for the young generation 402void JvmtiTagMap::get_young_generation() { 403 CollectedHeap* ch = Universe::heap(); 404 switch (ch->kind()) { 405 case (CollectedHeap::GenCollectedHeap): { 406 _young_gen = ((GenCollectedHeap*)ch)->get_gen(0)->reserved(); 407 break; 408 } 409#ifndef SERIALGC 410 case (CollectedHeap::ParallelScavengeHeap): { 411 _young_gen = ((ParallelScavengeHeap*)ch)->young_gen()->reserved(); 412 break; 413 } 414 case (CollectedHeap::G1CollectedHeap): { 415 // Until a more satisfactory solution is implemented, all 416 // oops in the tag map will require rehash at each gc. 417 // This is a correct, if extremely inefficient solution. 418 // See RFE 6621729 for related commentary. 419 _young_gen = ch->reserved_region(); 420 break; 421 } 422#endif // !SERIALGC 423 default: 424 ShouldNotReachHere(); 425 } 426} 427 428// returns true if oop is in the young generation 429inline bool JvmtiTagMap::is_in_young(oop o) { 430 assert(_young_gen.start() != NULL, "checking"); 431 void* p = (void*)o; 432 bool in_young = _young_gen.contains(p); 433 return in_young; 434} 435 436// returns the appropriate hashmap for a given object 437inline JvmtiTagHashmap* JvmtiTagMap::hashmap_for(oop o) { 438 if (is_in_young(o)) { 439 return _hashmap[0]; 440 } else { 441 return _hashmap[1]; 442 } 443} 444 445 446// create a JvmtiTagMap 447JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) : 448 _env(env), 449 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false), 450 _free_entries(NULL), 451 _free_entries_count(0) 452{ 453 assert(JvmtiThreadState_lock->is_locked(), "sanity check"); 454 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment"); 455 456 // create the hashmaps 457 for (int i=0; i<n_hashmaps; i++) { 458 _hashmap[i] = new JvmtiTagHashmap(); 459 } 460 461 // get the memory region used by the young generation 462 get_young_generation(); 463 464 // finally add us to the environment 465 ((JvmtiEnvBase *)env)->set_tag_map(this); 466} 467 468 469// destroy a JvmtiTagMap 470JvmtiTagMap::~JvmtiTagMap() { 471 472 // no lock acquired as we assume the enclosing environment is 473 // also being destroryed. 474 ((JvmtiEnvBase *)_env)->set_tag_map(NULL); 475 476 // iterate over the hashmaps and destroy each of the entries 477 for (int i=0; i<n_hashmaps; i++) { 478 JvmtiTagHashmap* hashmap = _hashmap[i]; 479 JvmtiTagHashmapEntry** table = hashmap->table(); 480 for (int j=0; j<hashmap->size(); j++) { 481 JvmtiTagHashmapEntry *entry = table[j]; 482 while (entry != NULL) { 483 JvmtiTagHashmapEntry* next = entry->next(); 484 jweak ref = entry->object(); 485 JNIHandles::destroy_weak_global(ref); 486 delete entry; 487 entry = next; 488 } 489 } 490 491 // finally destroy the hashmap 492 delete hashmap; 493 } 494 495 // remove any entries on the free list 496 JvmtiTagHashmapEntry* entry = _free_entries; 497 while (entry != NULL) { 498 JvmtiTagHashmapEntry* next = entry->next(); 499 delete entry; 500 entry = next; 501 } 502} 503 504// create a hashmap entry 505// - if there's an entry on the (per-environment) free list then this 506// is returned. Otherwise an new entry is allocated. 507JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(jweak ref, jlong tag) { 508 assert(Thread::current()->is_VM_thread() || is_locked(), "checking"); 509 JvmtiTagHashmapEntry* entry; 510 if (_free_entries == NULL) { 511 entry = new JvmtiTagHashmapEntry(ref, tag); 512 } else { 513 assert(_free_entries_count > 0, "mismatched _free_entries_count"); 514 _free_entries_count--; 515 entry = _free_entries; 516 _free_entries = entry->next(); 517 entry->init(ref, tag); 518 } 519 return entry; 520} 521 522// destroy an entry by returning it to the free list 523void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) { 524 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); 525 // limit the size of the free list 526 if (_free_entries_count >= max_free_entries) { 527 delete entry; 528 } else { 529 entry->set_next(_free_entries); 530 _free_entries = entry; 531 _free_entries_count++; 532 } 533} 534 535// returns the tag map for the given environments. If the tag map 536// doesn't exist then it is created. 537JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) { 538 JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map(); 539 if (tag_map == NULL) { 540 MutexLocker mu(JvmtiThreadState_lock); 541 tag_map = ((JvmtiEnvBase *)env)->tag_map(); 542 if (tag_map == NULL) { 543 tag_map = new JvmtiTagMap(env); 544 } 545 } else { 546 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); 547 } 548 return tag_map; 549} 550 551// iterate over all entries in the tag map. 552void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) { 553 for (int i=0; i<n_hashmaps; i++) { 554 JvmtiTagHashmap* hashmap = _hashmap[i]; 555 hashmap->entry_iterate(closure); 556 } 557} 558 559// returns true if the hashmaps are empty 560bool JvmtiTagMap::is_empty() { 561 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); 562 assert(n_hashmaps == 2, "not implemented"); 563 return ((_hashmap[0]->entry_count() == 0) && (_hashmap[1]->entry_count() == 0)); 564} 565 566 567// Return the tag value for an object, or 0 if the object is 568// not tagged 569// 570static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) { 571 JvmtiTagHashmapEntry* entry = tag_map->hashmap_for(o)->find(o); 572 if (entry == NULL) { 573 return 0; 574 } else { 575 return entry->tag(); 576 } 577} 578 579// If the object is a java.lang.Class then return the klassOop, 580// otherwise return the original object 581static inline oop klassOop_if_java_lang_Class(oop o) { 582 if (o->klass() == SystemDictionary::Class_klass()) { 583 if (!java_lang_Class::is_primitive(o)) { 584 o = (oop)java_lang_Class::as_klassOop(o); 585 assert(o != NULL, "class for non-primitive mirror must exist"); 586 } 587 } 588 return o; 589} 590 591// A CallbackWrapper is a support class for querying and tagging an object 592// around a callback to a profiler. The constructor does pre-callback 593// work to get the tag value, klass tag value, ... and the destructor 594// does the post-callback work of tagging or untagging the object. 595// 596// { 597// CallbackWrapper wrapper(tag_map, o); 598// 599// (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...) 600// 601// } // wrapper goes out of scope here which results in the destructor 602// checking to see if the object has been tagged, untagged, or the 603// tag value has changed. 604// 605class CallbackWrapper : public StackObj { 606 private: 607 JvmtiTagMap* _tag_map; 608 JvmtiTagHashmap* _hashmap; 609 JvmtiTagHashmapEntry* _entry; 610 oop _o; 611 jlong _obj_size; 612 jlong _obj_tag; 613 klassOop _klass; // the object's class 614 jlong _klass_tag; 615 616 protected: 617 JvmtiTagMap* tag_map() const { return _tag_map; } 618 619 // invoked post-callback to tag, untag, or update the tag of an object 620 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap, 621 JvmtiTagHashmapEntry* entry, jlong obj_tag); 622 public: 623 CallbackWrapper(JvmtiTagMap* tag_map, oop o) { 624 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(), 625 "MT unsafe or must be VM thread"); 626 627 // for Classes the klassOop is tagged 628 _o = klassOop_if_java_lang_Class(o); 629 630 // object size 631 _obj_size = _o->size() * wordSize; 632 633 // record the context 634 _tag_map = tag_map; 635 _hashmap = tag_map->hashmap_for(_o); 636 _entry = _hashmap->find(_o); 637 638 // get object tag 639 _obj_tag = (_entry == NULL) ? 0 : _entry->tag(); 640 641 // get the class and the class's tag value 642 if (_o == o) { 643 _klass = _o->klass(); 644 } else { 645 // if the object represents a runtime class then use the 646 // tag for java.lang.Class 647 _klass = SystemDictionary::Class_klass(); 648 } 649 _klass_tag = tag_for(tag_map, _klass); 650 } 651 652 ~CallbackWrapper() { 653 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag); 654 } 655 656 inline jlong* obj_tag_p() { return &_obj_tag; } 657 inline jlong obj_size() const { return _obj_size; } 658 inline jlong obj_tag() const { return _obj_tag; } 659 inline klassOop klass() const { return _klass; } 660 inline jlong klass_tag() const { return _klass_tag; } 661}; 662 663 664 665// callback post-callback to tag, untag, or update the tag of an object 666void inline CallbackWrapper::post_callback_tag_update(oop o, 667 JvmtiTagHashmap* hashmap, 668 JvmtiTagHashmapEntry* entry, 669 jlong obj_tag) { 670 if (entry == NULL) { 671 if (obj_tag != 0) { 672 // callback has tagged the object 673 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 674 HandleMark hm; 675 Handle h(o); 676 jweak ref = JNIHandles::make_weak_global(h); 677 entry = tag_map()->create_entry(ref, obj_tag); 678 hashmap->add(o, entry); 679 } 680 } else { 681 // object was previously tagged - the callback may have untagged 682 // the object or changed the tag value 683 if (obj_tag == 0) { 684 jweak ref = entry->object(); 685 686 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o); 687 assert(entry_removed == entry, "checking"); 688 tag_map()->destroy_entry(entry); 689 690 JNIHandles::destroy_weak_global(ref); 691 } else { 692 if (obj_tag != entry->tag()) { 693 entry->set_tag(obj_tag); 694 } 695 } 696 } 697} 698 699// An extended CallbackWrapper used when reporting an object reference 700// to the agent. 701// 702// { 703// TwoOopCallbackWrapper wrapper(tag_map, referrer, o); 704// 705// (*callback)(wrapper.klass_tag(), 706// wrapper.obj_size(), 707// wrapper.obj_tag_p() 708// wrapper.referrer_tag_p(), ...) 709// 710// } // wrapper goes out of scope here which results in the destructor 711// checking to see if the referrer object has been tagged, untagged, 712// or the tag value has changed. 713// 714class TwoOopCallbackWrapper : public CallbackWrapper { 715 private: 716 bool _is_reference_to_self; 717 JvmtiTagHashmap* _referrer_hashmap; 718 JvmtiTagHashmapEntry* _referrer_entry; 719 oop _referrer; 720 jlong _referrer_obj_tag; 721 jlong _referrer_klass_tag; 722 jlong* _referrer_tag_p; 723 724 bool is_reference_to_self() const { return _is_reference_to_self; } 725 726 public: 727 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) : 728 CallbackWrapper(tag_map, o) 729 { 730 // self reference needs to be handled in a special way 731 _is_reference_to_self = (referrer == o); 732 733 if (_is_reference_to_self) { 734 _referrer_klass_tag = klass_tag(); 735 _referrer_tag_p = obj_tag_p(); 736 } else { 737 // for Classes the klassOop is tagged 738 _referrer = klassOop_if_java_lang_Class(referrer); 739 // record the context 740 _referrer_hashmap = tag_map->hashmap_for(_referrer); 741 _referrer_entry = _referrer_hashmap->find(_referrer); 742 743 // get object tag 744 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag(); 745 _referrer_tag_p = &_referrer_obj_tag; 746 747 // get referrer class tag. 748 klassOop k = (_referrer == referrer) ? // Check if referrer is a class... 749 _referrer->klass() // No, just get its class 750 : SystemDictionary::Class_klass(); // Yes, its class is Class 751 _referrer_klass_tag = tag_for(tag_map, k); 752 } 753 } 754 755 ~TwoOopCallbackWrapper() { 756 if (!is_reference_to_self()){ 757 post_callback_tag_update(_referrer, 758 _referrer_hashmap, 759 _referrer_entry, 760 _referrer_obj_tag); 761 } 762 } 763 764 // address of referrer tag 765 // (for a self reference this will return the same thing as obj_tag_p()) 766 inline jlong* referrer_tag_p() { return _referrer_tag_p; } 767 768 // referrer's class tag 769 inline jlong referrer_klass_tag() { return _referrer_klass_tag; } 770}; 771 772// tag an object 773// 774// This function is performance critical. If many threads attempt to tag objects 775// around the same time then it's possible that the Mutex associated with the 776// tag map will be a hot lock. Eliminating this lock will not eliminate the issue 777// because creating a JNI weak reference requires acquiring a global lock also. 778void JvmtiTagMap::set_tag(jobject object, jlong tag) { 779 MutexLocker ml(lock()); 780 781 // resolve the object 782 oop o = JNIHandles::resolve_non_null(object); 783 784 // for Classes we tag the klassOop 785 o = klassOop_if_java_lang_Class(o); 786 787 // see if the object is already tagged 788 JvmtiTagHashmap* hashmap = hashmap_for(o); 789 JvmtiTagHashmapEntry* entry = hashmap->find(o); 790 791 // if the object is not already tagged then we tag it 792 if (entry == NULL) { 793 if (tag != 0) { 794 HandleMark hm; 795 Handle h(o); 796 jweak ref = JNIHandles::make_weak_global(h); 797 798 // the object may have moved because make_weak_global may 799 // have blocked - thus it is necessary resolve the handle 800 // and re-hash the object. 801 o = h(); 802 entry = create_entry(ref, tag); 803 hashmap_for(o)->add(o, entry); 804 } else { 805 // no-op 806 } 807 } else { 808 // if the object is already tagged then we either update 809 // the tag (if a new tag value has been provided) 810 // or remove the object if the new tag value is 0. 811 // Removing the object requires that we also delete the JNI 812 // weak ref to the object. 813 if (tag == 0) { 814 jweak ref = entry->object(); 815 hashmap->remove(o); 816 destroy_entry(entry); 817 JNIHandles::destroy_weak_global(ref); 818 } else { 819 entry->set_tag(tag); 820 } 821 } 822} 823 824// get the tag for an object 825jlong JvmtiTagMap::get_tag(jobject object) { 826 MutexLocker ml(lock()); 827 828 // resolve the object 829 oop o = JNIHandles::resolve_non_null(object); 830 831 // for Classes get the tag from the klassOop 832 return tag_for(this, klassOop_if_java_lang_Class(o)); 833} 834 835 836// Helper class used to describe the static or instance fields of a class. 837// For each field it holds the field index (as defined by the JVMTI specification), 838// the field type, and the offset. 839 840class ClassFieldDescriptor: public CHeapObj { 841 private: 842 int _field_index; 843 int _field_offset; 844 char _field_type; 845 public: 846 ClassFieldDescriptor(int index, char type, int offset) : 847 _field_index(index), _field_type(type), _field_offset(offset) { 848 } 849 int field_index() const { return _field_index; } 850 char field_type() const { return _field_type; } 851 int field_offset() const { return _field_offset; } 852}; 853 854class ClassFieldMap: public CHeapObj { 855 private: 856 enum { 857 initial_field_count = 5 858 }; 859 860 // list of field descriptors 861 GrowableArray<ClassFieldDescriptor*>* _fields; 862 863 // constructor 864 ClassFieldMap(); 865 866 // add a field 867 void add(int index, char type, int offset); 868 869 // returns the field count for the given class 870 static int compute_field_count(instanceKlassHandle ikh); 871 872 public: 873 ~ClassFieldMap(); 874 875 // access 876 int field_count() { return _fields->length(); } 877 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); } 878 879 // functions to create maps of static or instance fields 880 static ClassFieldMap* create_map_of_static_fields(klassOop k); 881 static ClassFieldMap* create_map_of_instance_fields(oop obj); 882}; 883 884ClassFieldMap::ClassFieldMap() { 885 _fields = new (ResourceObj::C_HEAP) GrowableArray<ClassFieldDescriptor*>(initial_field_count, true); 886} 887 888ClassFieldMap::~ClassFieldMap() { 889 for (int i=0; i<_fields->length(); i++) { 890 delete _fields->at(i); 891 } 892 delete _fields; 893} 894 895void ClassFieldMap::add(int index, char type, int offset) { 896 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset); 897 _fields->append(field); 898} 899 900// Returns a heap allocated ClassFieldMap to describe the static fields 901// of the given class. 902// 903ClassFieldMap* ClassFieldMap::create_map_of_static_fields(klassOop k) { 904 HandleMark hm; 905 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k); 906 907 // create the field map 908 ClassFieldMap* field_map = new ClassFieldMap(); 909 910 FilteredFieldStream f(ikh, false, false); 911 int max_field_index = f.field_count()-1; 912 913 int index = 0; 914 for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) { 915 // ignore instance fields 916 if (!fld.access_flags().is_static()) { 917 continue; 918 } 919 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset()); 920 } 921 return field_map; 922} 923 924// Returns a heap allocated ClassFieldMap to describe the instance fields 925// of the given class. All instance fields are included (this means public 926// and private fields declared in superclasses and superinterfaces too). 927// 928ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) { 929 HandleMark hm; 930 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass()); 931 932 // create the field map 933 ClassFieldMap* field_map = new ClassFieldMap(); 934 935 FilteredFieldStream f(ikh, false, false); 936 937 int max_field_index = f.field_count()-1; 938 939 int index = 0; 940 for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) { 941 // ignore static fields 942 if (fld.access_flags().is_static()) { 943 continue; 944 } 945 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset()); 946 } 947 948 return field_map; 949} 950 951// Helper class used to cache a ClassFileMap for the instance fields of 952// a cache. A JvmtiCachedClassFieldMap can be cached by an instanceKlass during 953// heap iteration and avoid creating a field map for each object in the heap 954// (only need to create the map when the first instance of a class is encountered). 955// 956class JvmtiCachedClassFieldMap : public CHeapObj { 957 private: 958 enum { 959 initial_class_count = 200 960 }; 961 ClassFieldMap* _field_map; 962 963 ClassFieldMap* field_map() const { return _field_map; } 964 965 JvmtiCachedClassFieldMap(ClassFieldMap* field_map); 966 ~JvmtiCachedClassFieldMap(); 967 968 static GrowableArray<instanceKlass*>* _class_list; 969 static void add_to_class_list(instanceKlass* ik); 970 971 public: 972 // returns the field map for a given object (returning map cached 973 // by instanceKlass if possible 974 static ClassFieldMap* get_map_of_instance_fields(oop obj); 975 976 // removes the field map from all instanceKlasses - should be 977 // called before VM operation completes 978 static void clear_cache(); 979 980 // returns the number of ClassFieldMap cached by instanceKlasses 981 static int cached_field_map_count(); 982}; 983 984GrowableArray<instanceKlass*>* JvmtiCachedClassFieldMap::_class_list; 985 986JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) { 987 _field_map = field_map; 988} 989 990JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() { 991 if (_field_map != NULL) { 992 delete _field_map; 993 } 994} 995 996// Marker class to ensure that the class file map cache is only used in a defined 997// scope. 998class ClassFieldMapCacheMark : public StackObj { 999 private: 1000 static bool _is_active; 1001 public: 1002 ClassFieldMapCacheMark() { 1003 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 1004 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty"); 1005 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested"); 1006 _is_active = true; 1007 } 1008 ~ClassFieldMapCacheMark() { 1009 JvmtiCachedClassFieldMap::clear_cache(); 1010 _is_active = false; 1011 } 1012 static bool is_active() { return _is_active; } 1013}; 1014 1015bool ClassFieldMapCacheMark::_is_active; 1016 1017 1018// record that the given instanceKlass is caching a field map 1019void JvmtiCachedClassFieldMap::add_to_class_list(instanceKlass* ik) { 1020 if (_class_list == NULL) { 1021 _class_list = new (ResourceObj::C_HEAP) GrowableArray<instanceKlass*>(initial_class_count, true); 1022 } 1023 _class_list->push(ik); 1024} 1025 1026// returns the instance field map for the given object 1027// (returns field map cached by the instanceKlass if possible) 1028ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) { 1029 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 1030 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active"); 1031 1032 klassOop k = obj->klass(); 1033 instanceKlass* ik = instanceKlass::cast(k); 1034 1035 // return cached map if possible 1036 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); 1037 if (cached_map != NULL) { 1038 assert(cached_map->field_map() != NULL, "missing field list"); 1039 return cached_map->field_map(); 1040 } else { 1041 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj); 1042 cached_map = new JvmtiCachedClassFieldMap(field_map); 1043 ik->set_jvmti_cached_class_field_map(cached_map); 1044 add_to_class_list(ik); 1045 return field_map; 1046 } 1047} 1048 1049// remove the fields maps cached from all instanceKlasses 1050void JvmtiCachedClassFieldMap::clear_cache() { 1051 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 1052 if (_class_list != NULL) { 1053 for (int i = 0; i < _class_list->length(); i++) { 1054 instanceKlass* ik = _class_list->at(i); 1055 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); 1056 assert(cached_map != NULL, "should not be NULL"); 1057 ik->set_jvmti_cached_class_field_map(NULL); 1058 delete cached_map; // deletes the encapsulated field map 1059 } 1060 delete _class_list; 1061 _class_list = NULL; 1062 } 1063} 1064 1065// returns the number of ClassFieldMap cached by instanceKlasses 1066int JvmtiCachedClassFieldMap::cached_field_map_count() { 1067 return (_class_list == NULL) ? 0 : _class_list->length(); 1068} 1069 1070// helper function to indicate if an object is filtered by its tag or class tag 1071static inline bool is_filtered_by_heap_filter(jlong obj_tag, 1072 jlong klass_tag, 1073 int heap_filter) { 1074 // apply the heap filter 1075 if (obj_tag != 0) { 1076 // filter out tagged objects 1077 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true; 1078 } else { 1079 // filter out untagged objects 1080 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true; 1081 } 1082 if (klass_tag != 0) { 1083 // filter out objects with tagged classes 1084 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true; 1085 } else { 1086 // filter out objects with untagged classes. 1087 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true; 1088 } 1089 return false; 1090} 1091 1092// helper function to indicate if an object is filtered by a klass filter 1093static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) { 1094 if (!klass_filter.is_null()) { 1095 if (obj->klass() != klass_filter()) { 1096 return true; 1097 } 1098 } 1099 return false; 1100} 1101 1102// helper function to tell if a field is a primitive field or not 1103static inline bool is_primitive_field_type(char type) { 1104 return (type != 'L' && type != '['); 1105} 1106 1107// helper function to copy the value from location addr to jvalue. 1108static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) { 1109 switch (value_type) { 1110 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; } 1111 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; } 1112 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; } 1113 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; } 1114 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; } 1115 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; } 1116 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; } 1117 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; } 1118 default: ShouldNotReachHere(); 1119 } 1120} 1121 1122// helper function to invoke string primitive value callback 1123// returns visit control flags 1124static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb, 1125 CallbackWrapper* wrapper, 1126 oop str, 1127 void* user_data) 1128{ 1129 assert(str->klass() == SystemDictionary::String_klass(), "not a string"); 1130 1131 // get the string value and length 1132 // (string value may be offset from the base) 1133 int s_len = java_lang_String::length(str); 1134 typeArrayOop s_value = java_lang_String::value(str); 1135 int s_offset = java_lang_String::offset(str); 1136 jchar* value; 1137 if (s_len > 0) { 1138 value = s_value->char_at_addr(s_offset); 1139 } else { 1140 value = (jchar*) s_value->base(T_CHAR); 1141 } 1142 1143 // invoke the callback 1144 return (*cb)(wrapper->klass_tag(), 1145 wrapper->obj_size(), 1146 wrapper->obj_tag_p(), 1147 value, 1148 (jint)s_len, 1149 user_data); 1150} 1151 1152// helper function to invoke string primitive value callback 1153// returns visit control flags 1154static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb, 1155 CallbackWrapper* wrapper, 1156 oop obj, 1157 void* user_data) 1158{ 1159 assert(obj->is_typeArray(), "not a primitive array"); 1160 1161 // get base address of first element 1162 typeArrayOop array = typeArrayOop(obj); 1163 BasicType type = typeArrayKlass::cast(array->klass())->element_type(); 1164 void* elements = array->base(type); 1165 1166 // jvmtiPrimitiveType is defined so this mapping is always correct 1167 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type); 1168 1169 return (*cb)(wrapper->klass_tag(), 1170 wrapper->obj_size(), 1171 wrapper->obj_tag_p(), 1172 (jint)array->length(), 1173 elem_type, 1174 elements, 1175 user_data); 1176} 1177 1178// helper function to invoke the primitive field callback for all static fields 1179// of a given class 1180static jint invoke_primitive_field_callback_for_static_fields 1181 (CallbackWrapper* wrapper, 1182 oop obj, 1183 jvmtiPrimitiveFieldCallback cb, 1184 void* user_data) 1185{ 1186 // for static fields only the index will be set 1187 static jvmtiHeapReferenceInfo reference_info = { 0 }; 1188 1189 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class"); 1190 if (java_lang_Class::is_primitive(obj)) { 1191 return 0; 1192 } 1193 klassOop k = java_lang_Class::as_klassOop(obj); 1194 Klass* klass = k->klass_part(); 1195 1196 // ignore classes for object and type arrays 1197 if (!klass->oop_is_instance()) { 1198 return 0; 1199 } 1200 1201 // ignore classes which aren't linked yet 1202 instanceKlass* ik = instanceKlass::cast(k); 1203 if (!ik->is_linked()) { 1204 return 0; 1205 } 1206 1207 // get the field map 1208 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k); 1209 1210 // invoke the callback for each static primitive field 1211 for (int i=0; i<field_map->field_count(); i++) { 1212 ClassFieldDescriptor* field = field_map->field_at(i); 1213 1214 // ignore non-primitive fields 1215 char type = field->field_type(); 1216 if (!is_primitive_field_type(type)) { 1217 continue; 1218 } 1219 // one-to-one mapping 1220 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 1221 1222 // get offset and field value 1223 int offset = field->field_offset(); 1224 address addr = (address)k + offset; 1225 jvalue value; 1226 copy_to_jvalue(&value, addr, value_type); 1227 1228 // field index 1229 reference_info.field.index = field->field_index(); 1230 1231 // invoke the callback 1232 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD, 1233 &reference_info, 1234 wrapper->klass_tag(), 1235 wrapper->obj_tag_p(), 1236 value, 1237 value_type, 1238 user_data); 1239 if (res & JVMTI_VISIT_ABORT) { 1240 delete field_map; 1241 return res; 1242 } 1243 } 1244 1245 delete field_map; 1246 return 0; 1247} 1248 1249// helper function to invoke the primitive field callback for all instance fields 1250// of a given object 1251static jint invoke_primitive_field_callback_for_instance_fields( 1252 CallbackWrapper* wrapper, 1253 oop obj, 1254 jvmtiPrimitiveFieldCallback cb, 1255 void* user_data) 1256{ 1257 // for instance fields only the index will be set 1258 static jvmtiHeapReferenceInfo reference_info = { 0 }; 1259 1260 // get the map of the instance fields 1261 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj); 1262 1263 // invoke the callback for each instance primitive field 1264 for (int i=0; i<fields->field_count(); i++) { 1265 ClassFieldDescriptor* field = fields->field_at(i); 1266 1267 // ignore non-primitive fields 1268 char type = field->field_type(); 1269 if (!is_primitive_field_type(type)) { 1270 continue; 1271 } 1272 // one-to-one mapping 1273 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 1274 1275 // get offset and field value 1276 int offset = field->field_offset(); 1277 address addr = (address)obj + offset; 1278 jvalue value; 1279 copy_to_jvalue(&value, addr, value_type); 1280 1281 // field index 1282 reference_info.field.index = field->field_index(); 1283 1284 // invoke the callback 1285 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD, 1286 &reference_info, 1287 wrapper->klass_tag(), 1288 wrapper->obj_tag_p(), 1289 value, 1290 value_type, 1291 user_data); 1292 if (res & JVMTI_VISIT_ABORT) { 1293 return res; 1294 } 1295 } 1296 return 0; 1297} 1298 1299 1300// VM operation to iterate over all objects in the heap (both reachable 1301// and unreachable) 1302class VM_HeapIterateOperation: public VM_Operation { 1303 private: 1304 ObjectClosure* _blk; 1305 public: 1306 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; } 1307 1308 VMOp_Type type() const { return VMOp_HeapIterateOperation; } 1309 void doit() { 1310 // allows class files maps to be cached during iteration 1311 ClassFieldMapCacheMark cm; 1312 1313 // make sure that heap is parsable (fills TLABs with filler objects) 1314 Universe::heap()->ensure_parsability(false); // no need to retire TLABs 1315 1316 // Verify heap before iteration - if the heap gets corrupted then 1317 // JVMTI's IterateOverHeap will crash. 1318 if (VerifyBeforeIteration) { 1319 Universe::verify(); 1320 } 1321 1322 // do the iteration 1323 // If this operation encounters a bad object when using CMS, 1324 // consider using safe_object_iterate() which avoids perm gen 1325 // objects that may contain bad references. 1326 Universe::heap()->object_iterate(_blk); 1327 1328 // when sharing is enabled we must iterate over the shared spaces 1329 if (UseSharedSpaces) { 1330 GenCollectedHeap* gch = GenCollectedHeap::heap(); 1331 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen(); 1332 gen->ro_space()->object_iterate(_blk); 1333 gen->rw_space()->object_iterate(_blk); 1334 } 1335 } 1336 1337}; 1338 1339 1340// An ObjectClosure used to support the deprecated IterateOverHeap and 1341// IterateOverInstancesOfClass functions 1342class IterateOverHeapObjectClosure: public ObjectClosure { 1343 private: 1344 JvmtiTagMap* _tag_map; 1345 KlassHandle _klass; 1346 jvmtiHeapObjectFilter _object_filter; 1347 jvmtiHeapObjectCallback _heap_object_callback; 1348 const void* _user_data; 1349 1350 // accessors 1351 JvmtiTagMap* tag_map() const { return _tag_map; } 1352 jvmtiHeapObjectFilter object_filter() const { return _object_filter; } 1353 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; } 1354 KlassHandle klass() const { return _klass; } 1355 const void* user_data() const { return _user_data; } 1356 1357 // indicates if iteration has been aborted 1358 bool _iteration_aborted; 1359 bool is_iteration_aborted() const { return _iteration_aborted; } 1360 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; } 1361 1362 public: 1363 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map, 1364 KlassHandle klass, 1365 jvmtiHeapObjectFilter object_filter, 1366 jvmtiHeapObjectCallback heap_object_callback, 1367 const void* user_data) : 1368 _tag_map(tag_map), 1369 _klass(klass), 1370 _object_filter(object_filter), 1371 _heap_object_callback(heap_object_callback), 1372 _user_data(user_data), 1373 _iteration_aborted(false) 1374 { 1375 } 1376 1377 void do_object(oop o); 1378}; 1379 1380// invoked for each object in the heap 1381void IterateOverHeapObjectClosure::do_object(oop o) { 1382 // check if iteration has been halted 1383 if (is_iteration_aborted()) return; 1384 1385 // ignore any objects that aren't visible to profiler 1386 if (!ServiceUtil::visible_oop(o)) return; 1387 1388 // instanceof check when filtering by klass 1389 if (!klass().is_null() && !o->is_a(klass()())) { 1390 return; 1391 } 1392 // prepare for the calllback 1393 CallbackWrapper wrapper(tag_map(), o); 1394 1395 // if the object is tagged and we're only interested in untagged objects 1396 // then don't invoke the callback. Similiarly, if the object is untagged 1397 // and we're only interested in tagged objects we skip the callback. 1398 if (wrapper.obj_tag() != 0) { 1399 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return; 1400 } else { 1401 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return; 1402 } 1403 1404 // invoke the agent's callback 1405 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(), 1406 wrapper.obj_size(), 1407 wrapper.obj_tag_p(), 1408 (void*)user_data()); 1409 if (control == JVMTI_ITERATION_ABORT) { 1410 set_iteration_aborted(true); 1411 } 1412} 1413 1414// An ObjectClosure used to support the IterateThroughHeap function 1415class IterateThroughHeapObjectClosure: public ObjectClosure { 1416 private: 1417 JvmtiTagMap* _tag_map; 1418 KlassHandle _klass; 1419 int _heap_filter; 1420 const jvmtiHeapCallbacks* _callbacks; 1421 const void* _user_data; 1422 1423 // accessor functions 1424 JvmtiTagMap* tag_map() const { return _tag_map; } 1425 int heap_filter() const { return _heap_filter; } 1426 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; } 1427 KlassHandle klass() const { return _klass; } 1428 const void* user_data() const { return _user_data; } 1429 1430 // indicates if the iteration has been aborted 1431 bool _iteration_aborted; 1432 bool is_iteration_aborted() const { return _iteration_aborted; } 1433 1434 // used to check the visit control flags. If the abort flag is set 1435 // then we set the iteration aborted flag so that the iteration completes 1436 // without processing any further objects 1437 bool check_flags_for_abort(jint flags) { 1438 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0; 1439 if (is_abort) { 1440 _iteration_aborted = true; 1441 } 1442 return is_abort; 1443 } 1444 1445 public: 1446 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map, 1447 KlassHandle klass, 1448 int heap_filter, 1449 const jvmtiHeapCallbacks* heap_callbacks, 1450 const void* user_data) : 1451 _tag_map(tag_map), 1452 _klass(klass), 1453 _heap_filter(heap_filter), 1454 _callbacks(heap_callbacks), 1455 _user_data(user_data), 1456 _iteration_aborted(false) 1457 { 1458 } 1459 1460 void do_object(oop o); 1461}; 1462 1463// invoked for each object in the heap 1464void IterateThroughHeapObjectClosure::do_object(oop obj) { 1465 // check if iteration has been halted 1466 if (is_iteration_aborted()) return; 1467 1468 // ignore any objects that aren't visible to profiler 1469 if (!ServiceUtil::visible_oop(obj)) return; 1470 1471 // apply class filter 1472 if (is_filtered_by_klass_filter(obj, klass())) return; 1473 1474 // prepare for callback 1475 CallbackWrapper wrapper(tag_map(), obj); 1476 1477 // check if filtered by the heap filter 1478 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) { 1479 return; 1480 } 1481 1482 // for arrays we need the length, otherwise -1 1483 bool is_array = obj->is_array(); 1484 int len = is_array ? arrayOop(obj)->length() : -1; 1485 1486 // invoke the object callback (if callback is provided) 1487 if (callbacks()->heap_iteration_callback != NULL) { 1488 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback; 1489 jint res = (*cb)(wrapper.klass_tag(), 1490 wrapper.obj_size(), 1491 wrapper.obj_tag_p(), 1492 (jint)len, 1493 (void*)user_data()); 1494 if (check_flags_for_abort(res)) return; 1495 } 1496 1497 // for objects and classes we report primitive fields if callback provided 1498 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) { 1499 jint res; 1500 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback; 1501 if (obj->klass() == SystemDictionary::Class_klass()) { 1502 res = invoke_primitive_field_callback_for_static_fields(&wrapper, 1503 obj, 1504 cb, 1505 (void*)user_data()); 1506 } else { 1507 res = invoke_primitive_field_callback_for_instance_fields(&wrapper, 1508 obj, 1509 cb, 1510 (void*)user_data()); 1511 } 1512 if (check_flags_for_abort(res)) return; 1513 } 1514 1515 // string callback 1516 if (!is_array && 1517 callbacks()->string_primitive_value_callback != NULL && 1518 obj->klass() == SystemDictionary::String_klass()) { 1519 jint res = invoke_string_value_callback( 1520 callbacks()->string_primitive_value_callback, 1521 &wrapper, 1522 obj, 1523 (void*)user_data() ); 1524 if (check_flags_for_abort(res)) return; 1525 } 1526 1527 // array callback 1528 if (is_array && 1529 callbacks()->array_primitive_value_callback != NULL && 1530 obj->is_typeArray()) { 1531 jint res = invoke_array_primitive_value_callback( 1532 callbacks()->array_primitive_value_callback, 1533 &wrapper, 1534 obj, 1535 (void*)user_data() ); 1536 if (check_flags_for_abort(res)) return; 1537 } 1538}; 1539 1540 1541// Deprecated function to iterate over all objects in the heap 1542void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter, 1543 KlassHandle klass, 1544 jvmtiHeapObjectCallback heap_object_callback, 1545 const void* user_data) 1546{ 1547 MutexLocker ml(Heap_lock); 1548 IterateOverHeapObjectClosure blk(this, 1549 klass, 1550 object_filter, 1551 heap_object_callback, 1552 user_data); 1553 VM_HeapIterateOperation op(&blk); 1554 VMThread::execute(&op); 1555} 1556 1557 1558// Iterates over all objects in the heap 1559void JvmtiTagMap::iterate_through_heap(jint heap_filter, 1560 KlassHandle klass, 1561 const jvmtiHeapCallbacks* callbacks, 1562 const void* user_data) 1563{ 1564 MutexLocker ml(Heap_lock); 1565 IterateThroughHeapObjectClosure blk(this, 1566 klass, 1567 heap_filter, 1568 callbacks, 1569 user_data); 1570 VM_HeapIterateOperation op(&blk); 1571 VMThread::execute(&op); 1572} 1573 1574// support class for get_objects_with_tags 1575 1576class TagObjectCollector : public JvmtiTagHashmapEntryClosure { 1577 private: 1578 JvmtiEnv* _env; 1579 jlong* _tags; 1580 jint _tag_count; 1581 1582 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs) 1583 GrowableArray<uint64_t>* _tag_results; // collected tags 1584 1585 public: 1586 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) { 1587 _env = env; 1588 _tags = (jlong*)tags; 1589 _tag_count = tag_count; 1590 _object_results = new (ResourceObj::C_HEAP) GrowableArray<jobject>(1,true); 1591 _tag_results = new (ResourceObj::C_HEAP) GrowableArray<uint64_t>(1,true); 1592 } 1593 1594 ~TagObjectCollector() { 1595 delete _object_results; 1596 delete _tag_results; 1597 } 1598 1599 // for each tagged object check if the tag value matches 1600 // - if it matches then we create a JNI local reference to the object 1601 // and record the reference and tag value. 1602 // 1603 void do_entry(JvmtiTagHashmapEntry* entry) { 1604 for (int i=0; i<_tag_count; i++) { 1605 if (_tags[i] == entry->tag()) { 1606 oop o = JNIHandles::resolve(entry->object()); 1607 assert(o != NULL && o != JNIHandles::deleted_handle(), "sanity check"); 1608 1609 // the mirror is tagged 1610 if (o->is_klass()) { 1611 klassOop k = (klassOop)o; 1612 o = Klass::cast(k)->java_mirror(); 1613 } 1614 1615 jobject ref = JNIHandles::make_local(JavaThread::current(), o); 1616 _object_results->append(ref); 1617 _tag_results->append((uint64_t)entry->tag()); 1618 } 1619 } 1620 } 1621 1622 // return the results from the collection 1623 // 1624 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { 1625 jvmtiError error; 1626 int count = _object_results->length(); 1627 assert(count >= 0, "sanity check"); 1628 1629 // if object_result_ptr is not NULL then allocate the result and copy 1630 // in the object references. 1631 if (object_result_ptr != NULL) { 1632 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr); 1633 if (error != JVMTI_ERROR_NONE) { 1634 return error; 1635 } 1636 for (int i=0; i<count; i++) { 1637 (*object_result_ptr)[i] = _object_results->at(i); 1638 } 1639 } 1640 1641 // if tag_result_ptr is not NULL then allocate the result and copy 1642 // in the tag values. 1643 if (tag_result_ptr != NULL) { 1644 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr); 1645 if (error != JVMTI_ERROR_NONE) { 1646 if (object_result_ptr != NULL) { 1647 _env->Deallocate((unsigned char*)object_result_ptr); 1648 } 1649 return error; 1650 } 1651 for (int i=0; i<count; i++) { 1652 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i); 1653 } 1654 } 1655 1656 *count_ptr = count; 1657 return JVMTI_ERROR_NONE; 1658 } 1659}; 1660 1661// return the list of objects with the specified tags 1662jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags, 1663 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { 1664 1665 TagObjectCollector collector(env(), tags, count); 1666 { 1667 // iterate over all tagged objects 1668 MutexLocker ml(lock()); 1669 entry_iterate(&collector); 1670 } 1671 return collector.result(count_ptr, object_result_ptr, tag_result_ptr); 1672} 1673 1674 1675// ObjectMarker is used to support the marking objects when walking the 1676// heap. 1677// 1678// This implementation uses the existing mark bits in an object for 1679// marking. Objects that are marked must later have their headers restored. 1680// As most objects are unlocked and don't have their identity hash computed 1681// we don't have to save their headers. Instead we save the headers that 1682// are "interesting". Later when the headers are restored this implementation 1683// restores all headers to their initial value and then restores the few 1684// objects that had interesting headers. 1685// 1686// Future work: This implementation currently uses growable arrays to save 1687// the oop and header of interesting objects. As an optimization we could 1688// use the same technique as the GC and make use of the unused area 1689// between top() and end(). 1690// 1691 1692// An ObjectClosure used to restore the mark bits of an object 1693class RestoreMarksClosure : public ObjectClosure { 1694 public: 1695 void do_object(oop o) { 1696 if (o != NULL) { 1697 markOop mark = o->mark(); 1698 if (mark->is_marked()) { 1699 o->init_mark(); 1700 } 1701 } 1702 } 1703}; 1704 1705// ObjectMarker provides the mark and visited functions 1706class ObjectMarker : AllStatic { 1707 private: 1708 // saved headers 1709 static GrowableArray<oop>* _saved_oop_stack; 1710 static GrowableArray<markOop>* _saved_mark_stack; 1711 1712 public: 1713 static void init(); // initialize 1714 static void done(); // clean-up 1715 1716 static inline void mark(oop o); // mark an object 1717 static inline bool visited(oop o); // check if object has been visited 1718}; 1719 1720GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL; 1721GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL; 1722 1723// initialize ObjectMarker - prepares for object marking 1724void ObjectMarker::init() { 1725 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 1726 1727 // prepare heap for iteration 1728 Universe::heap()->ensure_parsability(false); // no need to retire TLABs 1729 1730 // create stacks for interesting headers 1731 _saved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(4000, true); 1732 _saved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true); 1733 1734 if (UseBiasedLocking) { 1735 BiasedLocking::preserve_marks(); 1736 } 1737} 1738 1739// Object marking is done so restore object headers 1740void ObjectMarker::done() { 1741 // iterate over all objects and restore the mark bits to 1742 // their initial value 1743 RestoreMarksClosure blk; 1744 Universe::heap()->object_iterate(&blk); 1745 1746 // When sharing is enabled we need to restore the headers of the objects 1747 // in the readwrite space too. 1748 if (UseSharedSpaces) { 1749 GenCollectedHeap* gch = GenCollectedHeap::heap(); 1750 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen(); 1751 gen->rw_space()->object_iterate(&blk); 1752 } 1753 1754 // now restore the interesting headers 1755 for (int i = 0; i < _saved_oop_stack->length(); i++) { 1756 oop o = _saved_oop_stack->at(i); 1757 markOop mark = _saved_mark_stack->at(i); 1758 o->set_mark(mark); 1759 } 1760 1761 if (UseBiasedLocking) { 1762 BiasedLocking::restore_marks(); 1763 } 1764 1765 // free the stacks 1766 delete _saved_oop_stack; 1767 delete _saved_mark_stack; 1768} 1769 1770// mark an object 1771inline void ObjectMarker::mark(oop o) { 1772 assert(Universe::heap()->is_in(o), "sanity check"); 1773 assert(!o->mark()->is_marked(), "should only mark an object once"); 1774 1775 // object's mark word 1776 markOop mark = o->mark(); 1777 1778 if (mark->must_be_preserved(o)) { 1779 _saved_mark_stack->push(mark); 1780 _saved_oop_stack->push(o); 1781 } 1782 1783 // mark the object 1784 o->set_mark(markOopDesc::prototype()->set_marked()); 1785} 1786 1787// return true if object is marked 1788inline bool ObjectMarker::visited(oop o) { 1789 return o->mark()->is_marked(); 1790} 1791 1792// Stack allocated class to help ensure that ObjectMarker is used 1793// correctly. Constructor initializes ObjectMarker, destructor calls 1794// ObjectMarker's done() function to restore object headers. 1795class ObjectMarkerController : public StackObj { 1796 public: 1797 ObjectMarkerController() { 1798 ObjectMarker::init(); 1799 } 1800 ~ObjectMarkerController() { 1801 ObjectMarker::done(); 1802 } 1803}; 1804 1805 1806// helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind 1807// (not performance critical as only used for roots) 1808static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) { 1809 switch (kind) { 1810 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL; 1811 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS; 1812 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR; 1813 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL; 1814 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL; 1815 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD; 1816 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER; 1817 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER; 1818 } 1819} 1820 1821// Base class for all heap walk contexts. The base class maintains a flag 1822// to indicate if the context is valid or not. 1823class HeapWalkContext VALUE_OBJ_CLASS_SPEC { 1824 private: 1825 bool _valid; 1826 public: 1827 HeapWalkContext(bool valid) { _valid = valid; } 1828 void invalidate() { _valid = false; } 1829 bool is_valid() const { return _valid; } 1830}; 1831 1832// A basic heap walk context for the deprecated heap walking functions. 1833// The context for a basic heap walk are the callbacks and fields used by 1834// the referrer caching scheme. 1835class BasicHeapWalkContext: public HeapWalkContext { 1836 private: 1837 jvmtiHeapRootCallback _heap_root_callback; 1838 jvmtiStackReferenceCallback _stack_ref_callback; 1839 jvmtiObjectReferenceCallback _object_ref_callback; 1840 1841 // used for caching 1842 oop _last_referrer; 1843 jlong _last_referrer_tag; 1844 1845 public: 1846 BasicHeapWalkContext() : HeapWalkContext(false) { } 1847 1848 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback, 1849 jvmtiStackReferenceCallback stack_ref_callback, 1850 jvmtiObjectReferenceCallback object_ref_callback) : 1851 HeapWalkContext(true), 1852 _heap_root_callback(heap_root_callback), 1853 _stack_ref_callback(stack_ref_callback), 1854 _object_ref_callback(object_ref_callback), 1855 _last_referrer(NULL), 1856 _last_referrer_tag(0) { 1857 } 1858 1859 // accessors 1860 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; } 1861 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; } 1862 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; } 1863 1864 oop last_referrer() const { return _last_referrer; } 1865 void set_last_referrer(oop referrer) { _last_referrer = referrer; } 1866 jlong last_referrer_tag() const { return _last_referrer_tag; } 1867 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; } 1868}; 1869 1870// The advanced heap walk context for the FollowReferences functions. 1871// The context is the callbacks, and the fields used for filtering. 1872class AdvancedHeapWalkContext: public HeapWalkContext { 1873 private: 1874 jint _heap_filter; 1875 KlassHandle _klass_filter; 1876 const jvmtiHeapCallbacks* _heap_callbacks; 1877 1878 public: 1879 AdvancedHeapWalkContext() : HeapWalkContext(false) { } 1880 1881 AdvancedHeapWalkContext(jint heap_filter, 1882 KlassHandle klass_filter, 1883 const jvmtiHeapCallbacks* heap_callbacks) : 1884 HeapWalkContext(true), 1885 _heap_filter(heap_filter), 1886 _klass_filter(klass_filter), 1887 _heap_callbacks(heap_callbacks) { 1888 } 1889 1890 // accessors 1891 jint heap_filter() const { return _heap_filter; } 1892 KlassHandle klass_filter() const { return _klass_filter; } 1893 1894 const jvmtiHeapReferenceCallback heap_reference_callback() const { 1895 return _heap_callbacks->heap_reference_callback; 1896 }; 1897 const jvmtiPrimitiveFieldCallback primitive_field_callback() const { 1898 return _heap_callbacks->primitive_field_callback; 1899 } 1900 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const { 1901 return _heap_callbacks->array_primitive_value_callback; 1902 } 1903 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const { 1904 return _heap_callbacks->string_primitive_value_callback; 1905 } 1906}; 1907 1908// The CallbackInvoker is a class with static functions that the heap walk can call 1909// into to invoke callbacks. It works in one of two modes. The "basic" mode is 1910// used for the deprecated IterateOverReachableObjects functions. The "advanced" 1911// mode is for the newer FollowReferences function which supports a lot of 1912// additional callbacks. 1913class CallbackInvoker : AllStatic { 1914 private: 1915 // heap walk styles 1916 enum { basic, advanced }; 1917 static int _heap_walk_type; 1918 static bool is_basic_heap_walk() { return _heap_walk_type == basic; } 1919 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; } 1920 1921 // context for basic style heap walk 1922 static BasicHeapWalkContext _basic_context; 1923 static BasicHeapWalkContext* basic_context() { 1924 assert(_basic_context.is_valid(), "invalid"); 1925 return &_basic_context; 1926 } 1927 1928 // context for advanced style heap walk 1929 static AdvancedHeapWalkContext _advanced_context; 1930 static AdvancedHeapWalkContext* advanced_context() { 1931 assert(_advanced_context.is_valid(), "invalid"); 1932 return &_advanced_context; 1933 } 1934 1935 // context needed for all heap walks 1936 static JvmtiTagMap* _tag_map; 1937 static const void* _user_data; 1938 static GrowableArray<oop>* _visit_stack; 1939 1940 // accessors 1941 static JvmtiTagMap* tag_map() { return _tag_map; } 1942 static const void* user_data() { return _user_data; } 1943 static GrowableArray<oop>* visit_stack() { return _visit_stack; } 1944 1945 // if the object hasn't been visited then push it onto the visit stack 1946 // so that it will be visited later 1947 static inline bool check_for_visit(oop obj) { 1948 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj); 1949 return true; 1950 } 1951 1952 // invoke basic style callbacks 1953 static inline bool invoke_basic_heap_root_callback 1954 (jvmtiHeapRootKind root_kind, oop obj); 1955 static inline bool invoke_basic_stack_ref_callback 1956 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method, 1957 int slot, oop obj); 1958 static inline bool invoke_basic_object_reference_callback 1959 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index); 1960 1961 // invoke advanced style callbacks 1962 static inline bool invoke_advanced_heap_root_callback 1963 (jvmtiHeapReferenceKind ref_kind, oop obj); 1964 static inline bool invoke_advanced_stack_ref_callback 1965 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth, 1966 jmethodID method, jlocation bci, jint slot, oop obj); 1967 static inline bool invoke_advanced_object_reference_callback 1968 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index); 1969 1970 // used to report the value of primitive fields 1971 static inline bool report_primitive_field 1972 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type); 1973 1974 public: 1975 // initialize for basic mode 1976 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, 1977 GrowableArray<oop>* visit_stack, 1978 const void* user_data, 1979 BasicHeapWalkContext context); 1980 1981 // initialize for advanced mode 1982 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, 1983 GrowableArray<oop>* visit_stack, 1984 const void* user_data, 1985 AdvancedHeapWalkContext context); 1986 1987 // functions to report roots 1988 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o); 1989 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth, 1990 jmethodID m, oop o); 1991 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth, 1992 jmethodID method, jlocation bci, jint slot, oop o); 1993 1994 // functions to report references 1995 static inline bool report_array_element_reference(oop referrer, oop referree, jint index); 1996 static inline bool report_class_reference(oop referrer, oop referree); 1997 static inline bool report_class_loader_reference(oop referrer, oop referree); 1998 static inline bool report_signers_reference(oop referrer, oop referree); 1999 static inline bool report_protection_domain_reference(oop referrer, oop referree); 2000 static inline bool report_superclass_reference(oop referrer, oop referree); 2001 static inline bool report_interface_reference(oop referrer, oop referree); 2002 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot); 2003 static inline bool report_field_reference(oop referrer, oop referree, jint slot); 2004 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index); 2005 static inline bool report_primitive_array_values(oop array); 2006 static inline bool report_string_value(oop str); 2007 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type); 2008 static inline bool report_primitive_static_field(oop o, jint index, address value, char type); 2009}; 2010 2011// statics 2012int CallbackInvoker::_heap_walk_type; 2013BasicHeapWalkContext CallbackInvoker::_basic_context; 2014AdvancedHeapWalkContext CallbackInvoker::_advanced_context; 2015JvmtiTagMap* CallbackInvoker::_tag_map; 2016const void* CallbackInvoker::_user_data; 2017GrowableArray<oop>* CallbackInvoker::_visit_stack; 2018 2019// initialize for basic heap walk (IterateOverReachableObjects et al) 2020void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, 2021 GrowableArray<oop>* visit_stack, 2022 const void* user_data, 2023 BasicHeapWalkContext context) { 2024 _tag_map = tag_map; 2025 _visit_stack = visit_stack; 2026 _user_data = user_data; 2027 _basic_context = context; 2028 _advanced_context.invalidate(); // will trigger assertion if used 2029 _heap_walk_type = basic; 2030} 2031 2032// initialize for advanced heap walk (FollowReferences) 2033void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, 2034 GrowableArray<oop>* visit_stack, 2035 const void* user_data, 2036 AdvancedHeapWalkContext context) { 2037 _tag_map = tag_map; 2038 _visit_stack = visit_stack; 2039 _user_data = user_data; 2040 _advanced_context = context; 2041 _basic_context.invalidate(); // will trigger assertion if used 2042 _heap_walk_type = advanced; 2043} 2044 2045 2046// invoke basic style heap root callback 2047inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) { 2048 assert(ServiceUtil::visible_oop(obj), "checking"); 2049 2050 // if we heap roots should be reported 2051 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback(); 2052 if (cb == NULL) { 2053 return check_for_visit(obj); 2054 } 2055 2056 CallbackWrapper wrapper(tag_map(), obj); 2057 jvmtiIterationControl control = (*cb)(root_kind, 2058 wrapper.klass_tag(), 2059 wrapper.obj_size(), 2060 wrapper.obj_tag_p(), 2061 (void*)user_data()); 2062 // push root to visit stack when following references 2063 if (control == JVMTI_ITERATION_CONTINUE && 2064 basic_context()->object_ref_callback() != NULL) { 2065 visit_stack()->push(obj); 2066 } 2067 return control != JVMTI_ITERATION_ABORT; 2068} 2069 2070// invoke basic style stack ref callback 2071inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind, 2072 jlong thread_tag, 2073 jint depth, 2074 jmethodID method, 2075 jint slot, 2076 oop obj) { 2077 assert(ServiceUtil::visible_oop(obj), "checking"); 2078 2079 // if we stack refs should be reported 2080 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback(); 2081 if (cb == NULL) { 2082 return check_for_visit(obj); 2083 } 2084 2085 CallbackWrapper wrapper(tag_map(), obj); 2086 jvmtiIterationControl control = (*cb)(root_kind, 2087 wrapper.klass_tag(), 2088 wrapper.obj_size(), 2089 wrapper.obj_tag_p(), 2090 thread_tag, 2091 depth, 2092 method, 2093 slot, 2094 (void*)user_data()); 2095 // push root to visit stack when following references 2096 if (control == JVMTI_ITERATION_CONTINUE && 2097 basic_context()->object_ref_callback() != NULL) { 2098 visit_stack()->push(obj); 2099 } 2100 return control != JVMTI_ITERATION_ABORT; 2101} 2102 2103// invoke basic style object reference callback 2104inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind, 2105 oop referrer, 2106 oop referree, 2107 jint index) { 2108 2109 assert(ServiceUtil::visible_oop(referrer), "checking"); 2110 assert(ServiceUtil::visible_oop(referree), "checking"); 2111 2112 BasicHeapWalkContext* context = basic_context(); 2113 2114 // callback requires the referrer's tag. If it's the same referrer 2115 // as the last call then we use the cached value. 2116 jlong referrer_tag; 2117 if (referrer == context->last_referrer()) { 2118 referrer_tag = context->last_referrer_tag(); 2119 } else { 2120 referrer_tag = tag_for(tag_map(), klassOop_if_java_lang_Class(referrer)); 2121 } 2122 2123 // do the callback 2124 CallbackWrapper wrapper(tag_map(), referree); 2125 jvmtiObjectReferenceCallback cb = context->object_ref_callback(); 2126 jvmtiIterationControl control = (*cb)(ref_kind, 2127 wrapper.klass_tag(), 2128 wrapper.obj_size(), 2129 wrapper.obj_tag_p(), 2130 referrer_tag, 2131 index, 2132 (void*)user_data()); 2133 2134 // record referrer and referrer tag. For self-references record the 2135 // tag value from the callback as this might differ from referrer_tag. 2136 context->set_last_referrer(referrer); 2137 if (referrer == referree) { 2138 context->set_last_referrer_tag(*wrapper.obj_tag_p()); 2139 } else { 2140 context->set_last_referrer_tag(referrer_tag); 2141 } 2142 2143 if (control == JVMTI_ITERATION_CONTINUE) { 2144 return check_for_visit(referree); 2145 } else { 2146 return control != JVMTI_ITERATION_ABORT; 2147 } 2148} 2149 2150// invoke advanced style heap root callback 2151inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind, 2152 oop obj) { 2153 assert(ServiceUtil::visible_oop(obj), "checking"); 2154 2155 AdvancedHeapWalkContext* context = advanced_context(); 2156 2157 // check that callback is provided 2158 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 2159 if (cb == NULL) { 2160 return check_for_visit(obj); 2161 } 2162 2163 // apply class filter 2164 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2165 return check_for_visit(obj); 2166 } 2167 2168 // setup the callback wrapper 2169 CallbackWrapper wrapper(tag_map(), obj); 2170 2171 // apply tag filter 2172 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2173 wrapper.klass_tag(), 2174 context->heap_filter())) { 2175 return check_for_visit(obj); 2176 } 2177 2178 // for arrays we need the length, otherwise -1 2179 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 2180 2181 // invoke the callback 2182 jint res = (*cb)(ref_kind, 2183 NULL, // referrer info 2184 wrapper.klass_tag(), 2185 0, // referrer_class_tag is 0 for heap root 2186 wrapper.obj_size(), 2187 wrapper.obj_tag_p(), 2188 NULL, // referrer_tag_p 2189 len, 2190 (void*)user_data()); 2191 if (res & JVMTI_VISIT_ABORT) { 2192 return false;// referrer class tag 2193 } 2194 if (res & JVMTI_VISIT_OBJECTS) { 2195 check_for_visit(obj); 2196 } 2197 return true; 2198} 2199 2200// report a reference from a thread stack to an object 2201inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind, 2202 jlong thread_tag, 2203 jlong tid, 2204 int depth, 2205 jmethodID method, 2206 jlocation bci, 2207 jint slot, 2208 oop obj) { 2209 assert(ServiceUtil::visible_oop(obj), "checking"); 2210 2211 AdvancedHeapWalkContext* context = advanced_context(); 2212 2213 // check that callback is provider 2214 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 2215 if (cb == NULL) { 2216 return check_for_visit(obj); 2217 } 2218 2219 // apply class filter 2220 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2221 return check_for_visit(obj); 2222 } 2223 2224 // setup the callback wrapper 2225 CallbackWrapper wrapper(tag_map(), obj); 2226 2227 // apply tag filter 2228 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2229 wrapper.klass_tag(), 2230 context->heap_filter())) { 2231 return check_for_visit(obj); 2232 } 2233 2234 // setup the referrer info 2235 jvmtiHeapReferenceInfo reference_info; 2236 reference_info.stack_local.thread_tag = thread_tag; 2237 reference_info.stack_local.thread_id = tid; 2238 reference_info.stack_local.depth = depth; 2239 reference_info.stack_local.method = method; 2240 reference_info.stack_local.location = bci; 2241 reference_info.stack_local.slot = slot; 2242 2243 // for arrays we need the length, otherwise -1 2244 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 2245 2246 // call into the agent 2247 int res = (*cb)(ref_kind, 2248 &reference_info, 2249 wrapper.klass_tag(), 2250 0, // referrer_class_tag is 0 for heap root (stack) 2251 wrapper.obj_size(), 2252 wrapper.obj_tag_p(), 2253 NULL, // referrer_tag is 0 for root 2254 len, 2255 (void*)user_data()); 2256 2257 if (res & JVMTI_VISIT_ABORT) { 2258 return false; 2259 } 2260 if (res & JVMTI_VISIT_OBJECTS) { 2261 check_for_visit(obj); 2262 } 2263 return true; 2264} 2265 2266// This mask is used to pass reference_info to a jvmtiHeapReferenceCallback 2267// only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed. 2268#define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \ 2269 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \ 2270 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \ 2271 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \ 2272 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \ 2273 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL)) 2274 2275// invoke the object reference callback to report a reference 2276inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind, 2277 oop referrer, 2278 oop obj, 2279 jint index) 2280{ 2281 // field index is only valid field in reference_info 2282 static jvmtiHeapReferenceInfo reference_info = { 0 }; 2283 2284 assert(ServiceUtil::visible_oop(referrer), "checking"); 2285 assert(ServiceUtil::visible_oop(obj), "checking"); 2286 2287 AdvancedHeapWalkContext* context = advanced_context(); 2288 2289 // check that callback is provider 2290 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 2291 if (cb == NULL) { 2292 return check_for_visit(obj); 2293 } 2294 2295 // apply class filter 2296 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2297 return check_for_visit(obj); 2298 } 2299 2300 // setup the callback wrapper 2301 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj); 2302 2303 // apply tag filter 2304 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2305 wrapper.klass_tag(), 2306 context->heap_filter())) { 2307 return check_for_visit(obj); 2308 } 2309 2310 // field index is only valid field in reference_info 2311 reference_info.field.index = index; 2312 2313 // for arrays we need the length, otherwise -1 2314 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 2315 2316 // invoke the callback 2317 int res = (*cb)(ref_kind, 2318 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL, 2319 wrapper.klass_tag(), 2320 wrapper.referrer_klass_tag(), 2321 wrapper.obj_size(), 2322 wrapper.obj_tag_p(), 2323 wrapper.referrer_tag_p(), 2324 len, 2325 (void*)user_data()); 2326 2327 if (res & JVMTI_VISIT_ABORT) { 2328 return false; 2329 } 2330 if (res & JVMTI_VISIT_OBJECTS) { 2331 check_for_visit(obj); 2332 } 2333 return true; 2334} 2335 2336// report a "simple root" 2337inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) { 2338 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL && 2339 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root"); 2340 assert(ServiceUtil::visible_oop(obj), "checking"); 2341 2342 if (is_basic_heap_walk()) { 2343 // map to old style root kind 2344 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind); 2345 return invoke_basic_heap_root_callback(root_kind, obj); 2346 } else { 2347 assert(is_advanced_heap_walk(), "wrong heap walk type"); 2348 return invoke_advanced_heap_root_callback(kind, obj); 2349 } 2350} 2351 2352 2353// invoke the primitive array values 2354inline bool CallbackInvoker::report_primitive_array_values(oop obj) { 2355 assert(obj->is_typeArray(), "not a primitive array"); 2356 2357 AdvancedHeapWalkContext* context = advanced_context(); 2358 assert(context->array_primitive_value_callback() != NULL, "no callback"); 2359 2360 // apply class filter 2361 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2362 return true; 2363 } 2364 2365 CallbackWrapper wrapper(tag_map(), obj); 2366 2367 // apply tag filter 2368 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2369 wrapper.klass_tag(), 2370 context->heap_filter())) { 2371 return true; 2372 } 2373 2374 // invoke the callback 2375 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(), 2376 &wrapper, 2377 obj, 2378 (void*)user_data()); 2379 return (!(res & JVMTI_VISIT_ABORT)); 2380} 2381 2382// invoke the string value callback 2383inline bool CallbackInvoker::report_string_value(oop str) { 2384 assert(str->klass() == SystemDictionary::String_klass(), "not a string"); 2385 2386 AdvancedHeapWalkContext* context = advanced_context(); 2387 assert(context->string_primitive_value_callback() != NULL, "no callback"); 2388 2389 // apply class filter 2390 if (is_filtered_by_klass_filter(str, context->klass_filter())) { 2391 return true; 2392 } 2393 2394 CallbackWrapper wrapper(tag_map(), str); 2395 2396 // apply tag filter 2397 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2398 wrapper.klass_tag(), 2399 context->heap_filter())) { 2400 return true; 2401 } 2402 2403 // invoke the callback 2404 int res = invoke_string_value_callback(context->string_primitive_value_callback(), 2405 &wrapper, 2406 str, 2407 (void*)user_data()); 2408 return (!(res & JVMTI_VISIT_ABORT)); 2409} 2410 2411// invoke the primitive field callback 2412inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind, 2413 oop obj, 2414 jint index, 2415 address addr, 2416 char type) 2417{ 2418 // for primitive fields only the index will be set 2419 static jvmtiHeapReferenceInfo reference_info = { 0 }; 2420 2421 AdvancedHeapWalkContext* context = advanced_context(); 2422 assert(context->primitive_field_callback() != NULL, "no callback"); 2423 2424 // apply class filter 2425 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2426 return true; 2427 } 2428 2429 CallbackWrapper wrapper(tag_map(), obj); 2430 2431 // apply tag filter 2432 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2433 wrapper.klass_tag(), 2434 context->heap_filter())) { 2435 return true; 2436 } 2437 2438 // the field index in the referrer 2439 reference_info.field.index = index; 2440 2441 // map the type 2442 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 2443 2444 // setup the jvalue 2445 jvalue value; 2446 copy_to_jvalue(&value, addr, value_type); 2447 2448 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback(); 2449 int res = (*cb)(ref_kind, 2450 &reference_info, 2451 wrapper.klass_tag(), 2452 wrapper.obj_tag_p(), 2453 value, 2454 value_type, 2455 (void*)user_data()); 2456 return (!(res & JVMTI_VISIT_ABORT)); 2457} 2458 2459 2460// instance field 2461inline bool CallbackInvoker::report_primitive_instance_field(oop obj, 2462 jint index, 2463 address value, 2464 char type) { 2465 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD, 2466 obj, 2467 index, 2468 value, 2469 type); 2470} 2471 2472// static field 2473inline bool CallbackInvoker::report_primitive_static_field(oop obj, 2474 jint index, 2475 address value, 2476 char type) { 2477 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD, 2478 obj, 2479 index, 2480 value, 2481 type); 2482} 2483 2484// report a JNI local (root object) to the profiler 2485inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) { 2486 if (is_basic_heap_walk()) { 2487 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL, 2488 thread_tag, 2489 depth, 2490 m, 2491 -1, 2492 obj); 2493 } else { 2494 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL, 2495 thread_tag, tid, 2496 depth, 2497 m, 2498 (jlocation)-1, 2499 -1, 2500 obj); 2501 } 2502} 2503 2504 2505// report a local (stack reference, root object) 2506inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag, 2507 jlong tid, 2508 jint depth, 2509 jmethodID method, 2510 jlocation bci, 2511 jint slot, 2512 oop obj) { 2513 if (is_basic_heap_walk()) { 2514 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL, 2515 thread_tag, 2516 depth, 2517 method, 2518 slot, 2519 obj); 2520 } else { 2521 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL, 2522 thread_tag, 2523 tid, 2524 depth, 2525 method, 2526 bci, 2527 slot, 2528 obj); 2529 } 2530} 2531 2532// report an object referencing a class. 2533inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) { 2534 if (is_basic_heap_walk()) { 2535 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); 2536 } else { 2537 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1); 2538 } 2539} 2540 2541// report a class referencing its class loader. 2542inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) { 2543 if (is_basic_heap_walk()) { 2544 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1); 2545 } else { 2546 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1); 2547 } 2548} 2549 2550// report a class referencing its signers. 2551inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) { 2552 if (is_basic_heap_walk()) { 2553 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1); 2554 } else { 2555 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1); 2556 } 2557} 2558 2559// report a class referencing its protection domain.. 2560inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) { 2561 if (is_basic_heap_walk()) { 2562 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); 2563 } else { 2564 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); 2565 } 2566} 2567 2568// report a class referencing its superclass. 2569inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) { 2570 if (is_basic_heap_walk()) { 2571 // Send this to be consistent with past implementation 2572 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); 2573 } else { 2574 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1); 2575 } 2576} 2577 2578// report a class referencing one of its interfaces. 2579inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) { 2580 if (is_basic_heap_walk()) { 2581 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1); 2582 } else { 2583 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1); 2584 } 2585} 2586 2587// report a class referencing one of its static fields. 2588inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) { 2589 if (is_basic_heap_walk()) { 2590 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot); 2591 } else { 2592 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot); 2593 } 2594} 2595 2596// report an array referencing an element object 2597inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) { 2598 if (is_basic_heap_walk()) { 2599 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); 2600 } else { 2601 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); 2602 } 2603} 2604 2605// report an object referencing an instance field object 2606inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) { 2607 if (is_basic_heap_walk()) { 2608 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot); 2609 } else { 2610 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot); 2611 } 2612} 2613 2614// report an array referencing an element object 2615inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) { 2616 if (is_basic_heap_walk()) { 2617 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index); 2618 } else { 2619 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index); 2620 } 2621} 2622 2623// A supporting closure used to process simple roots 2624class SimpleRootsClosure : public OopClosure { 2625 private: 2626 jvmtiHeapReferenceKind _kind; 2627 bool _continue; 2628 2629 jvmtiHeapReferenceKind root_kind() { return _kind; } 2630 2631 public: 2632 void set_kind(jvmtiHeapReferenceKind kind) { 2633 _kind = kind; 2634 _continue = true; 2635 } 2636 2637 inline bool stopped() { 2638 return !_continue; 2639 } 2640 2641 void do_oop(oop* obj_p) { 2642 // iteration has terminated 2643 if (stopped()) { 2644 return; 2645 } 2646 2647 // ignore null or deleted handles 2648 oop o = *obj_p; 2649 if (o == NULL || o == JNIHandles::deleted_handle()) { 2650 return; 2651 } 2652 2653 jvmtiHeapReferenceKind kind = root_kind(); 2654 2655 // many roots are Klasses so we use the java mirror 2656 if (o->is_klass()) { 2657 klassOop k = (klassOop)o; 2658 o = Klass::cast(k)->java_mirror(); 2659 } else { 2660 2661 // SystemDictionary::always_strong_oops_do reports the application 2662 // class loader as a root. We want this root to be reported as 2663 // a root kind of "OTHER" rather than "SYSTEM_CLASS". 2664 if (o->is_instance() && root_kind() == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) { 2665 kind = JVMTI_HEAP_REFERENCE_OTHER; 2666 } 2667 } 2668 2669 // some objects are ignored - in the case of simple 2670 // roots it's mostly symbolOops that we are skipping 2671 // here. 2672 if (!ServiceUtil::visible_oop(o)) { 2673 return; 2674 } 2675 2676 // invoke the callback 2677 _continue = CallbackInvoker::report_simple_root(kind, o); 2678 2679 } 2680 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } 2681}; 2682 2683// A supporting closure used to process JNI locals 2684class JNILocalRootsClosure : public OopClosure { 2685 private: 2686 jlong _thread_tag; 2687 jlong _tid; 2688 jint _depth; 2689 jmethodID _method; 2690 bool _continue; 2691 public: 2692 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) { 2693 _thread_tag = thread_tag; 2694 _tid = tid; 2695 _depth = depth; 2696 _method = method; 2697 _continue = true; 2698 } 2699 2700 inline bool stopped() { 2701 return !_continue; 2702 } 2703 2704 void do_oop(oop* obj_p) { 2705 // iteration has terminated 2706 if (stopped()) { 2707 return; 2708 } 2709 2710 // ignore null or deleted handles 2711 oop o = *obj_p; 2712 if (o == NULL || o == JNIHandles::deleted_handle()) { 2713 return; 2714 } 2715 2716 if (!ServiceUtil::visible_oop(o)) { 2717 return; 2718 } 2719 2720 // invoke the callback 2721 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o); 2722 } 2723 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } 2724}; 2725 2726 2727// A VM operation to iterate over objects that are reachable from 2728// a set of roots or an initial object. 2729// 2730// For VM_HeapWalkOperation the set of roots used is :- 2731// 2732// - All JNI global references 2733// - All inflated monitors 2734// - All classes loaded by the boot class loader (or all classes 2735// in the event that class unloading is disabled) 2736// - All java threads 2737// - For each java thread then all locals and JNI local references 2738// on the thread's execution stack 2739// - All visible/explainable objects from Universes::oops_do 2740// 2741class VM_HeapWalkOperation: public VM_Operation { 2742 private: 2743 enum { 2744 initial_visit_stack_size = 4000 2745 }; 2746 2747 bool _is_advanced_heap_walk; // indicates FollowReferences 2748 JvmtiTagMap* _tag_map; 2749 Handle _initial_object; 2750 GrowableArray<oop>* _visit_stack; // the visit stack 2751 2752 bool _collecting_heap_roots; // are we collecting roots 2753 bool _following_object_refs; // are we following object references 2754 2755 bool _reporting_primitive_fields; // optional reporting 2756 bool _reporting_primitive_array_values; 2757 bool _reporting_string_values; 2758 2759 GrowableArray<oop>* create_visit_stack() { 2760 return new (ResourceObj::C_HEAP) GrowableArray<oop>(initial_visit_stack_size, true); 2761 } 2762 2763 // accessors 2764 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; } 2765 JvmtiTagMap* tag_map() const { return _tag_map; } 2766 Handle initial_object() const { return _initial_object; } 2767 2768 bool is_following_references() const { return _following_object_refs; } 2769 2770 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; } 2771 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; } 2772 bool is_reporting_string_values() const { return _reporting_string_values; } 2773 2774 GrowableArray<oop>* visit_stack() const { return _visit_stack; } 2775 2776 // iterate over the various object types 2777 inline bool iterate_over_array(oop o); 2778 inline bool iterate_over_type_array(oop o); 2779 inline bool iterate_over_class(klassOop o); 2780 inline bool iterate_over_object(oop o); 2781 2782 // root collection 2783 inline bool collect_simple_roots(); 2784 inline bool collect_stack_roots(); 2785 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk); 2786 2787 // visit an object 2788 inline bool visit(oop o); 2789 2790 public: 2791 VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2792 Handle initial_object, 2793 BasicHeapWalkContext callbacks, 2794 const void* user_data); 2795 2796 VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2797 Handle initial_object, 2798 AdvancedHeapWalkContext callbacks, 2799 const void* user_data); 2800 2801 ~VM_HeapWalkOperation(); 2802 2803 VMOp_Type type() const { return VMOp_HeapWalkOperation; } 2804 void doit(); 2805}; 2806 2807 2808VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2809 Handle initial_object, 2810 BasicHeapWalkContext callbacks, 2811 const void* user_data) { 2812 _is_advanced_heap_walk = false; 2813 _tag_map = tag_map; 2814 _initial_object = initial_object; 2815 _following_object_refs = (callbacks.object_ref_callback() != NULL); 2816 _reporting_primitive_fields = false; 2817 _reporting_primitive_array_values = false; 2818 _reporting_string_values = false; 2819 _visit_stack = create_visit_stack(); 2820 2821 2822 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks); 2823} 2824 2825VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2826 Handle initial_object, 2827 AdvancedHeapWalkContext callbacks, 2828 const void* user_data) { 2829 _is_advanced_heap_walk = true; 2830 _tag_map = tag_map; 2831 _initial_object = initial_object; 2832 _following_object_refs = true; 2833 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);; 2834 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);; 2835 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);; 2836 _visit_stack = create_visit_stack(); 2837 2838 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks); 2839} 2840 2841VM_HeapWalkOperation::~VM_HeapWalkOperation() { 2842 if (_following_object_refs) { 2843 assert(_visit_stack != NULL, "checking"); 2844 delete _visit_stack; 2845 _visit_stack = NULL; 2846 } 2847} 2848 2849// an array references its class and has a reference to 2850// each element in the array 2851inline bool VM_HeapWalkOperation::iterate_over_array(oop o) { 2852 objArrayOop array = objArrayOop(o); 2853 if (array->klass() == Universe::systemObjArrayKlassObj()) { 2854 // filtered out 2855 return true; 2856 } 2857 2858 // array reference to its class 2859 oop mirror = objArrayKlass::cast(array->klass())->java_mirror(); 2860 if (!CallbackInvoker::report_class_reference(o, mirror)) { 2861 return false; 2862 } 2863 2864 // iterate over the array and report each reference to a 2865 // non-null element 2866 for (int index=0; index<array->length(); index++) { 2867 oop elem = array->obj_at(index); 2868 if (elem == NULL) { 2869 continue; 2870 } 2871 2872 // report the array reference o[index] = elem 2873 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) { 2874 return false; 2875 } 2876 } 2877 return true; 2878} 2879 2880// a type array references its class 2881inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) { 2882 klassOop k = o->klass(); 2883 oop mirror = Klass::cast(k)->java_mirror(); 2884 if (!CallbackInvoker::report_class_reference(o, mirror)) { 2885 return false; 2886 } 2887 2888 // report the array contents if required 2889 if (is_reporting_primitive_array_values()) { 2890 if (!CallbackInvoker::report_primitive_array_values(o)) { 2891 return false; 2892 } 2893 } 2894 return true; 2895} 2896 2897// verify that a static oop field is in range 2898static inline bool verify_static_oop(instanceKlass* ik, 2899 klassOop k, int offset) { 2900 address obj_p = (address)k + offset; 2901 address start = (address)ik->start_of_static_fields(); 2902 address end = start + (ik->static_oop_field_size() * heapOopSize); 2903 assert(end >= start, "sanity check"); 2904 2905 if (obj_p >= start && obj_p < end) { 2906 return true; 2907 } else { 2908 return false; 2909 } 2910} 2911 2912// a class references its super class, interfaces, class loader, ... 2913// and finally its static fields 2914inline bool VM_HeapWalkOperation::iterate_over_class(klassOop k) { 2915 int i; 2916 Klass* klass = klassOop(k)->klass_part(); 2917 2918 if (klass->oop_is_instance()) { 2919 instanceKlass* ik = instanceKlass::cast(k); 2920 2921 // ignore the class if it's has been initialized yet 2922 if (!ik->is_linked()) { 2923 return true; 2924 } 2925 2926 // get the java mirror 2927 oop mirror = klass->java_mirror(); 2928 2929 // super (only if something more interesting than java.lang.Object) 2930 klassOop java_super = ik->java_super(); 2931 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) { 2932 oop super = Klass::cast(java_super)->java_mirror(); 2933 if (!CallbackInvoker::report_superclass_reference(mirror, super)) { 2934 return false; 2935 } 2936 } 2937 2938 // class loader 2939 oop cl = ik->class_loader(); 2940 if (cl != NULL) { 2941 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) { 2942 return false; 2943 } 2944 } 2945 2946 // protection domain 2947 oop pd = ik->protection_domain(); 2948 if (pd != NULL) { 2949 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) { 2950 return false; 2951 } 2952 } 2953 2954 // signers 2955 oop signers = ik->signers(); 2956 if (signers != NULL) { 2957 if (!CallbackInvoker::report_signers_reference(mirror, signers)) { 2958 return false; 2959 } 2960 } 2961 2962 // references from the constant pool 2963 { 2964 const constantPoolOop pool = ik->constants(); 2965 for (int i = 1; i < pool->length(); i++) { 2966 constantTag tag = pool->tag_at(i).value(); 2967 if (tag.is_string() || tag.is_klass()) { 2968 oop entry; 2969 if (tag.is_string()) { 2970 entry = pool->resolved_string_at(i); 2971 assert(java_lang_String::is_instance(entry), "must be string"); 2972 } else { 2973 entry = Klass::cast(pool->resolved_klass_at(i))->java_mirror(); 2974 } 2975 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) { 2976 return false; 2977 } 2978 } 2979 } 2980 } 2981 2982 // interfaces 2983 // (These will already have been reported as references from the constant pool 2984 // but are specified by IterateOverReachableObjects and must be reported). 2985 objArrayOop interfaces = ik->local_interfaces(); 2986 for (i = 0; i < interfaces->length(); i++) { 2987 oop interf = Klass::cast((klassOop)interfaces->obj_at(i))->java_mirror(); 2988 if (interf == NULL) { 2989 continue; 2990 } 2991 if (!CallbackInvoker::report_interface_reference(mirror, interf)) { 2992 return false; 2993 } 2994 } 2995 2996 // iterate over the static fields 2997 2998 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k); 2999 for (i=0; i<field_map->field_count(); i++) { 3000 ClassFieldDescriptor* field = field_map->field_at(i); 3001 char type = field->field_type(); 3002 if (!is_primitive_field_type(type)) { 3003 oop fld_o = k->obj_field(field->field_offset()); 3004 assert(verify_static_oop(ik, k, field->field_offset()), "sanity check"); 3005 if (fld_o != NULL) { 3006 int slot = field->field_index(); 3007 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) { 3008 delete field_map; 3009 return false; 3010 } 3011 } 3012 } else { 3013 if (is_reporting_primitive_fields()) { 3014 address addr = (address)k + field->field_offset(); 3015 int slot = field->field_index(); 3016 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) { 3017 delete field_map; 3018 return false; 3019 } 3020 } 3021 } 3022 } 3023 delete field_map; 3024 3025 return true; 3026 } 3027 3028 return true; 3029} 3030 3031// an object references a class and its instance fields 3032// (static fields are ignored here as we report these as 3033// references from the class). 3034inline bool VM_HeapWalkOperation::iterate_over_object(oop o) { 3035 // reference to the class 3036 if (!CallbackInvoker::report_class_reference(o, Klass::cast(o->klass())->java_mirror())) { 3037 return false; 3038 } 3039 3040 // iterate over instance fields 3041 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o); 3042 for (int i=0; i<field_map->field_count(); i++) { 3043 ClassFieldDescriptor* field = field_map->field_at(i); 3044 char type = field->field_type(); 3045 if (!is_primitive_field_type(type)) { 3046 oop fld_o = o->obj_field(field->field_offset()); 3047 if (fld_o != NULL) { 3048 // reflection code may have a reference to a klassOop. 3049 // - see sun.reflect.UnsafeStaticFieldAccessorImpl and sun.misc.Unsafe 3050 if (fld_o->is_klass()) { 3051 klassOop k = (klassOop)fld_o; 3052 fld_o = Klass::cast(k)->java_mirror(); 3053 } 3054 int slot = field->field_index(); 3055 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) { 3056 return false; 3057 } 3058 } 3059 } else { 3060 if (is_reporting_primitive_fields()) { 3061 // primitive instance field 3062 address addr = (address)o + field->field_offset(); 3063 int slot = field->field_index(); 3064 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) { 3065 return false; 3066 } 3067 } 3068 } 3069 } 3070 3071 // if the object is a java.lang.String 3072 if (is_reporting_string_values() && 3073 o->klass() == SystemDictionary::String_klass()) { 3074 if (!CallbackInvoker::report_string_value(o)) { 3075 return false; 3076 } 3077 } 3078 return true; 3079} 3080 3081 3082// collects all simple (non-stack) roots. 3083// if there's a heap root callback provided then the callback is 3084// invoked for each simple root. 3085// if an object reference callback is provided then all simple 3086// roots are pushed onto the marking stack so that they can be 3087// processed later 3088// 3089inline bool VM_HeapWalkOperation::collect_simple_roots() { 3090 SimpleRootsClosure blk; 3091 3092 // JNI globals 3093 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL); 3094 JNIHandles::oops_do(&blk); 3095 if (blk.stopped()) { 3096 return false; 3097 } 3098 3099 // Preloaded classes and loader from the system dictionary 3100 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS); 3101 SystemDictionary::always_strong_oops_do(&blk); 3102 if (blk.stopped()) { 3103 return false; 3104 } 3105 3106 // Inflated monitors 3107 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR); 3108 ObjectSynchronizer::oops_do(&blk); 3109 if (blk.stopped()) { 3110 return false; 3111 } 3112 3113 // Threads 3114 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) { 3115 oop threadObj = thread->threadObj(); 3116 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) { 3117 bool cont = CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, threadObj); 3118 if (!cont) { 3119 return false; 3120 } 3121 } 3122 } 3123 3124 // Other kinds of roots maintained by HotSpot 3125 // Many of these won't be visible but others (such as instances of important 3126 // exceptions) will be visible. 3127 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER); 3128 Universe::oops_do(&blk); 3129 3130 // If there are any non-perm roots in the code cache, visit them. 3131 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER); 3132 CodeBlobToOopClosure look_in_blobs(&blk, false); 3133 CodeCache::scavenge_root_nmethods_do(&look_in_blobs); 3134 3135 return true; 3136} 3137 3138// Walk the stack of a given thread and find all references (locals 3139// and JNI calls) and report these as stack references 3140inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread, 3141 JNILocalRootsClosure* blk) 3142{ 3143 oop threadObj = java_thread->threadObj(); 3144 assert(threadObj != NULL, "sanity check"); 3145 3146 // only need to get the thread's tag once per thread 3147 jlong thread_tag = tag_for(_tag_map, threadObj); 3148 3149 // also need the thread id 3150 jlong tid = java_lang_Thread::thread_id(threadObj); 3151 3152 3153 if (java_thread->has_last_Java_frame()) { 3154 3155 // vframes are resource allocated 3156 Thread* current_thread = Thread::current(); 3157 ResourceMark rm(current_thread); 3158 HandleMark hm(current_thread); 3159 3160 RegisterMap reg_map(java_thread); 3161 frame f = java_thread->last_frame(); 3162 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread); 3163 3164 bool is_top_frame = true; 3165 int depth = 0; 3166 frame* last_entry_frame = NULL; 3167 3168 while (vf != NULL) { 3169 if (vf->is_java_frame()) { 3170 3171 // java frame (interpreted, compiled, ...) 3172 javaVFrame *jvf = javaVFrame::cast(vf); 3173 3174 // the jmethodID 3175 jmethodID method = jvf->method()->jmethod_id(); 3176 3177 if (!(jvf->method()->is_native())) { 3178 jlocation bci = (jlocation)jvf->bci(); 3179 StackValueCollection* locals = jvf->locals(); 3180 for (int slot=0; slot<locals->size(); slot++) { 3181 if (locals->at(slot)->type() == T_OBJECT) { 3182 oop o = locals->obj_at(slot)(); 3183 if (o == NULL) { 3184 continue; 3185 } 3186 3187 // stack reference 3188 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method, 3189 bci, slot, o)) { 3190 return false; 3191 } 3192 } 3193 } 3194 } else { 3195 blk->set_context(thread_tag, tid, depth, method); 3196 if (is_top_frame) { 3197 // JNI locals for the top frame. 3198 java_thread->active_handles()->oops_do(blk); 3199 } else { 3200 if (last_entry_frame != NULL) { 3201 // JNI locals for the entry frame 3202 assert(last_entry_frame->is_entry_frame(), "checking"); 3203 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk); 3204 } 3205 } 3206 } 3207 last_entry_frame = NULL; 3208 depth++; 3209 } else { 3210 // externalVFrame - for an entry frame then we report the JNI locals 3211 // when we find the corresponding javaVFrame 3212 frame* fr = vf->frame_pointer(); 3213 assert(fr != NULL, "sanity check"); 3214 if (fr->is_entry_frame()) { 3215 last_entry_frame = fr; 3216 } 3217 } 3218 3219 vf = vf->sender(); 3220 is_top_frame = false; 3221 } 3222 } else { 3223 // no last java frame but there may be JNI locals 3224 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL); 3225 java_thread->active_handles()->oops_do(blk); 3226 } 3227 return true; 3228} 3229 3230 3231// collects all stack roots - for each thread it walks the execution 3232// stack to find all references and local JNI refs. 3233inline bool VM_HeapWalkOperation::collect_stack_roots() { 3234 JNILocalRootsClosure blk; 3235 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) { 3236 oop threadObj = thread->threadObj(); 3237 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) { 3238 if (!collect_stack_roots(thread, &blk)) { 3239 return false; 3240 } 3241 } 3242 } 3243 return true; 3244} 3245 3246// visit an object 3247// first mark the object as visited 3248// second get all the outbound references from this object (in other words, all 3249// the objects referenced by this object). 3250// 3251bool VM_HeapWalkOperation::visit(oop o) { 3252 // mark object as visited 3253 assert(!ObjectMarker::visited(o), "can't visit same object more than once"); 3254 ObjectMarker::mark(o); 3255 3256 // instance 3257 if (o->is_instance()) { 3258 if (o->klass() == SystemDictionary::Class_klass()) { 3259 o = klassOop_if_java_lang_Class(o); 3260 if (o->is_klass()) { 3261 // a java.lang.Class 3262 return iterate_over_class(klassOop(o)); 3263 } 3264 } else { 3265 return iterate_over_object(o); 3266 } 3267 } 3268 3269 // object array 3270 if (o->is_objArray()) { 3271 return iterate_over_array(o); 3272 } 3273 3274 // type array 3275 if (o->is_typeArray()) { 3276 return iterate_over_type_array(o); 3277 } 3278 3279 return true; 3280} 3281 3282void VM_HeapWalkOperation::doit() { 3283 ResourceMark rm; 3284 ObjectMarkerController marker; 3285 ClassFieldMapCacheMark cm; 3286 3287 assert(visit_stack()->is_empty(), "visit stack must be empty"); 3288 3289 // the heap walk starts with an initial object or the heap roots 3290 if (initial_object().is_null()) { 3291 if (!collect_simple_roots()) return; 3292 if (!collect_stack_roots()) return; 3293 } else { 3294 visit_stack()->push(initial_object()()); 3295 } 3296 3297 // object references required 3298 if (is_following_references()) { 3299 3300 // visit each object until all reachable objects have been 3301 // visited or the callback asked to terminate the iteration. 3302 while (!visit_stack()->is_empty()) { 3303 oop o = visit_stack()->pop(); 3304 if (!ObjectMarker::visited(o)) { 3305 if (!visit(o)) { 3306 break; 3307 } 3308 } 3309 } 3310 } 3311} 3312 3313// iterate over all objects that are reachable from a set of roots 3314void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback, 3315 jvmtiStackReferenceCallback stack_ref_callback, 3316 jvmtiObjectReferenceCallback object_ref_callback, 3317 const void* user_data) { 3318 MutexLocker ml(Heap_lock); 3319 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback); 3320 VM_HeapWalkOperation op(this, Handle(), context, user_data); 3321 VMThread::execute(&op); 3322} 3323 3324// iterate over all objects that are reachable from a given object 3325void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object, 3326 jvmtiObjectReferenceCallback object_ref_callback, 3327 const void* user_data) { 3328 oop obj = JNIHandles::resolve(object); 3329 Handle initial_object(Thread::current(), obj); 3330 3331 MutexLocker ml(Heap_lock); 3332 BasicHeapWalkContext context(NULL, NULL, object_ref_callback); 3333 VM_HeapWalkOperation op(this, initial_object, context, user_data); 3334 VMThread::execute(&op); 3335} 3336 3337// follow references from an initial object or the GC roots 3338void JvmtiTagMap::follow_references(jint heap_filter, 3339 KlassHandle klass, 3340 jobject object, 3341 const jvmtiHeapCallbacks* callbacks, 3342 const void* user_data) 3343{ 3344 oop obj = JNIHandles::resolve(object); 3345 Handle initial_object(Thread::current(), obj); 3346 3347 MutexLocker ml(Heap_lock); 3348 AdvancedHeapWalkContext context(heap_filter, klass, callbacks); 3349 VM_HeapWalkOperation op(this, initial_object, context, user_data); 3350 VMThread::execute(&op); 3351} 3352 3353 3354// called post-GC 3355// - for each JVMTI environment with an object tag map, call its rehash 3356// function to re-sync with the new object locations. 3357void JvmtiTagMap::gc_epilogue(bool full) { 3358 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); 3359 if (JvmtiEnv::environments_might_exist()) { 3360 // re-obtain the memory region for the young generation (might 3361 // changed due to adaptive resizing policy) 3362 get_young_generation(); 3363 3364 JvmtiEnvIterator it; 3365 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) { 3366 JvmtiTagMap* tag_map = env->tag_map(); 3367 if (tag_map != NULL && !tag_map->is_empty()) { 3368 TraceTime t(full ? "JVMTI Full Rehash " : "JVMTI Rehash ", TraceJVMTIObjectTagging); 3369 if (full) { 3370 tag_map->rehash(0, n_hashmaps); 3371 } else { 3372 tag_map->rehash(0, 0); // tag map for young gen only 3373 } 3374 } 3375 } 3376 } 3377} 3378 3379// CMS has completed referencing processing so we may have JNI weak refs 3380// to objects in the CMS generation that have been GC'ed. 3381void JvmtiTagMap::cms_ref_processing_epilogue() { 3382 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); 3383 assert(UseConcMarkSweepGC, "should only be used with CMS"); 3384 if (JvmtiEnv::environments_might_exist()) { 3385 JvmtiEnvIterator it; 3386 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) { 3387 JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map(); 3388 if (tag_map != NULL && !tag_map->is_empty()) { 3389 TraceTime t("JVMTI Rehash (CMS) ", TraceJVMTIObjectTagging); 3390 tag_map->rehash(1, n_hashmaps); // assume CMS not used in young gen 3391 } 3392 } 3393 } 3394} 3395 3396 3397// For each entry in the hashmaps 'start' to 'end' : 3398// 3399// 1. resolve the JNI weak reference 3400// 3401// 2. If it resolves to NULL it means the object has been freed so the entry 3402// is removed, the weak reference destroyed, and the object free event is 3403// posted (if enabled). 3404// 3405// 3. If the weak reference resolves to an object then we re-hash the object 3406// to see if it has moved or has been promoted (from the young to the old 3407// generation for example). 3408// 3409void JvmtiTagMap::rehash(int start, int end) { 3410 3411 // does this environment have the OBJECT_FREE event enabled 3412 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE); 3413 3414 // counters used for trace message 3415 int freed = 0; 3416 int moved = 0; 3417 int promoted = 0; 3418 3419 // we assume there are two hashmaps - one for the young generation 3420 // and the other for all other spaces. 3421 assert(n_hashmaps == 2, "not implemented"); 3422 JvmtiTagHashmap* young_hashmap = _hashmap[0]; 3423 JvmtiTagHashmap* other_hashmap = _hashmap[1]; 3424 3425 // reenable sizing (if disabled) 3426 young_hashmap->set_resizing_enabled(true); 3427 other_hashmap->set_resizing_enabled(true); 3428 3429 // when re-hashing the hashmap corresponding to the young generation we 3430 // collect the entries corresponding to objects that have been promoted. 3431 JvmtiTagHashmapEntry* promoted_entries = NULL; 3432 3433 if (end >= n_hashmaps) { 3434 end = n_hashmaps - 1; 3435 } 3436 3437 for (int i=start; i <= end; i++) { 3438 JvmtiTagHashmap* hashmap = _hashmap[i]; 3439 3440 // if the hashmap is empty then we can skip it 3441 if (hashmap->_entry_count == 0) { 3442 continue; 3443 } 3444 3445 // now iterate through each entry in the table 3446 3447 JvmtiTagHashmapEntry** table = hashmap->table(); 3448 int size = hashmap->size(); 3449 3450 for (int pos=0; pos<size; pos++) { 3451 JvmtiTagHashmapEntry* entry = table[pos]; 3452 JvmtiTagHashmapEntry* prev = NULL; 3453 3454 while (entry != NULL) { 3455 JvmtiTagHashmapEntry* next = entry->next(); 3456 3457 jweak ref = entry->object(); 3458 oop oop = JNIHandles::resolve(ref); 3459 3460 // has object been GC'ed 3461 if (oop == NULL) { 3462 // grab the tag 3463 jlong tag = entry->tag(); 3464 guarantee(tag != 0, "checking"); 3465 3466 // remove GC'ed entry from hashmap and return the 3467 // entry to the free list 3468 hashmap->remove(prev, pos, entry); 3469 destroy_entry(entry); 3470 3471 // destroy the weak ref 3472 JNIHandles::destroy_weak_global(ref); 3473 3474 // post the event to the profiler 3475 if (post_object_free) { 3476 JvmtiExport::post_object_free(env(), tag); 3477 } 3478 3479 freed++; 3480 entry = next; 3481 continue; 3482 } 3483 3484 // if this is the young hashmap then the object is either promoted 3485 // or moved. 3486 // if this is the other hashmap then the object is moved. 3487 3488 bool same_gen; 3489 if (i == 0) { 3490 assert(hashmap == young_hashmap, "checking"); 3491 same_gen = is_in_young(oop); 3492 } else { 3493 same_gen = true; 3494 } 3495 3496 3497 if (same_gen) { 3498 // if the object has moved then re-hash it and move its 3499 // entry to its new location. 3500 unsigned int new_pos = JvmtiTagHashmap::hash(oop, size); 3501 if (new_pos != (unsigned int)pos) { 3502 if (prev == NULL) { 3503 table[pos] = next; 3504 } else { 3505 prev->set_next(next); 3506 } 3507 entry->set_next(table[new_pos]); 3508 table[new_pos] = entry; 3509 moved++; 3510 } else { 3511 // object didn't move 3512 prev = entry; 3513 } 3514 } else { 3515 // object has been promoted so remove the entry from the 3516 // young hashmap 3517 assert(hashmap == young_hashmap, "checking"); 3518 hashmap->remove(prev, pos, entry); 3519 3520 // move the entry to the promoted list 3521 entry->set_next(promoted_entries); 3522 promoted_entries = entry; 3523 } 3524 3525 entry = next; 3526 } 3527 } 3528 } 3529 3530 3531 // add the entries, corresponding to the promoted objects, to the 3532 // other hashmap. 3533 JvmtiTagHashmapEntry* entry = promoted_entries; 3534 while (entry != NULL) { 3535 oop o = JNIHandles::resolve(entry->object()); 3536 assert(hashmap_for(o) == other_hashmap, "checking"); 3537 JvmtiTagHashmapEntry* next = entry->next(); 3538 other_hashmap->add(o, entry); 3539 entry = next; 3540 promoted++; 3541 } 3542 3543 // stats 3544 if (TraceJVMTIObjectTagging) { 3545 int total_moves = promoted + moved; 3546 3547 int post_total = 0; 3548 for (int i=0; i<n_hashmaps; i++) { 3549 post_total += _hashmap[i]->_entry_count; 3550 } 3551 int pre_total = post_total + freed; 3552 3553 tty->print("(%d->%d, %d freed, %d promoted, %d total moves)", 3554 pre_total, post_total, freed, promoted, total_moves); 3555 } 3556} 3557