1 /* 2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "jvmtifiles/jvmtiEnv.hpp" 30 #include "oops/instanceMirrorKlass.hpp" 31 #include "oops/objArrayKlass.hpp" 32 #include "oops/oop.inline2.hpp" 33 #include "prims/jvmtiEventController.hpp" 34 #include "prims/jvmtiEventController.inline.hpp" 35 #include "prims/jvmtiExport.hpp" 36 #include "prims/jvmtiImpl.hpp" 37 #include "prims/jvmtiTagMap.hpp" 38 #include "runtime/biasedLocking.hpp" 39 #include "runtime/javaCalls.hpp" 40 #include "runtime/jniHandles.hpp" 41 #include "runtime/mutex.hpp" 42 #include "runtime/mutexLocker.hpp" 43 #include "runtime/reflectionUtils.hpp" 44 #include "runtime/vframe.hpp" 45 #include "runtime/vmThread.hpp" 46 #include "runtime/vm_operations.hpp" 47 #include "services/serviceUtil.hpp" 48 #include "utilities/macros.hpp" 49 #if INCLUDE_ALL_GCS 50 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" 51 #endif // INCLUDE_ALL_GCS 52 53 // JvmtiTagHashmapEntry 54 // 55 // Each entry encapsulates a reference to the tagged object 56 // and the tag value. In addition an entry includes a next pointer which 57 // is used to chain entries together. 58 59 class JvmtiTagHashmapEntry : public CHeapObj<mtInternal> { 60 private: 61 friend class JvmtiTagMap; 62 63 oop _object; // tagged object 64 jlong _tag; // the tag 65 JvmtiTagHashmapEntry* _next; // next on the list 66 67 inline void init(oop object, jlong tag) { 68 _object = object; 69 _tag = tag; 70 _next = NULL; 71 } 72 73 // constructor 74 JvmtiTagHashmapEntry(oop object, jlong tag) { init(object, tag); } 75 76 public: 77 78 // accessor methods 79 inline oop object() const { return _object; } 80 inline oop* object_addr() { return &_object; } 81 inline jlong tag() const { return _tag; } 82 83 inline void set_tag(jlong tag) { 84 assert(tag != 0, "can't be zero"); 85 _tag = tag; 86 } 87 88 inline JvmtiTagHashmapEntry* next() const { return _next; } 89 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; } 90 }; 91 92 93 // JvmtiTagHashmap 94 // 95 // A hashmap is essentially a table of pointers to entries. Entries 96 // are hashed to a location, or position in the table, and then 97 // chained from that location. The "key" for hashing is address of 98 // the object, or oop. The "value" is the tag value. 99 // 100 // A hashmap maintains a count of the number entries in the hashmap 101 // and resizes if the number of entries exceeds a given threshold. 102 // The threshold is specified as a percentage of the size - for 103 // example a threshold of 0.75 will trigger the hashmap to resize 104 // if the number of entries is >75% of table size. 105 // 106 // A hashmap provides functions for adding, removing, and finding 107 // entries. It also provides a function to iterate over all entries 108 // in the hashmap. 109 110 class JvmtiTagHashmap : public CHeapObj<mtInternal> { 111 private: 112 friend class JvmtiTagMap; 113 114 enum { 115 small_trace_threshold = 10000, // threshold for tracing 116 medium_trace_threshold = 100000, 117 large_trace_threshold = 1000000, 118 initial_trace_threshold = small_trace_threshold 119 }; 120 121 static int _sizes[]; // array of possible hashmap sizes 122 int _size; // actual size of the table 123 int _size_index; // index into size table 124 125 int _entry_count; // number of entries in the hashmap 126 127 float _load_factor; // load factor as a % of the size 128 int _resize_threshold; // computed threshold to trigger resizing. 129 bool _resizing_enabled; // indicates if hashmap can resize 130 131 int _trace_threshold; // threshold for trace messages 132 133 JvmtiTagHashmapEntry** _table; // the table of entries. 134 135 // private accessors 136 int resize_threshold() const { return _resize_threshold; } 137 int trace_threshold() const { return _trace_threshold; } 138 139 // initialize the hashmap 140 void init(int size_index=0, float load_factor=4.0f) { 141 int initial_size = _sizes[size_index]; 142 _size_index = size_index; 143 _size = initial_size; 144 _entry_count = 0; 145 if (TraceJVMTIObjectTagging) { 146 _trace_threshold = initial_trace_threshold; 147 } else { 148 _trace_threshold = -1; 149 } 150 _load_factor = load_factor; 151 _resize_threshold = (int)(_load_factor * _size); 152 _resizing_enabled = true; 153 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*); 154 _table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal); 155 if (_table == NULL) { 156 vm_exit_out_of_memory(s, OOM_MALLOC_ERROR, 157 "unable to allocate initial hashtable for jvmti object tags"); 158 } 159 for (int i=0; i<initial_size; i++) { 160 _table[i] = NULL; 161 } 162 } 163 164 // hash a given key (oop) with the specified size 165 static unsigned int hash(oop key, int size) { 166 // shift right to get better distribution (as these bits will be zero 167 // with aligned addresses) 168 unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key)); 169 #ifdef _LP64 170 return (addr >> 3) % size; 171 #else 172 return (addr >> 2) % size; 173 #endif 174 } 175 176 // hash a given key (oop) 177 unsigned int hash(oop key) { 178 return hash(key, _size); 179 } 180 181 // resize the hashmap - allocates a large table and re-hashes 182 // all entries into the new table. 183 void resize() { 184 int new_size_index = _size_index+1; 185 int new_size = _sizes[new_size_index]; 186 if (new_size < 0) { 187 // hashmap already at maximum capacity 188 return; 189 } 190 191 // allocate new table 192 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*); 193 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal); 194 if (new_table == NULL) { 195 warning("unable to allocate larger hashtable for jvmti object tags"); 196 set_resizing_enabled(false); 197 return; 198 } 199 200 // initialize new table 201 int i; 202 for (i=0; i<new_size; i++) { 203 new_table[i] = NULL; 204 } 205 206 // rehash all entries into the new table 207 for (i=0; i<_size; i++) { 208 JvmtiTagHashmapEntry* entry = _table[i]; 209 while (entry != NULL) { 210 JvmtiTagHashmapEntry* next = entry->next(); 211 oop key = entry->object(); 212 assert(key != NULL, "jni weak reference cleared!!"); 213 unsigned int h = hash(key, new_size); 214 JvmtiTagHashmapEntry* anchor = new_table[h]; 215 if (anchor == NULL) { 216 new_table[h] = entry; 217 entry->set_next(NULL); 218 } else { 219 entry->set_next(anchor); 220 new_table[h] = entry; 221 } 222 entry = next; 223 } 224 } 225 226 // free old table and update settings. 227 os::free((void*)_table); 228 _table = new_table; 229 _size_index = new_size_index; 230 _size = new_size; 231 232 // compute new resize threshold 233 _resize_threshold = (int)(_load_factor * _size); 234 } 235 236 237 // internal remove function - remove an entry at a given position in the 238 // table. 239 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) { 240 assert(pos >= 0 && pos < _size, "out of range"); 241 if (prev == NULL) { 242 _table[pos] = entry->next(); 243 } else { 244 prev->set_next(entry->next()); 245 } 246 assert(_entry_count > 0, "checking"); 247 _entry_count--; 248 } 249 250 // resizing switch 251 bool is_resizing_enabled() const { return _resizing_enabled; } 252 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; } 253 254 // debugging 255 void print_memory_usage(); 256 void compute_next_trace_threshold(); 257 258 public: 259 260 // create a JvmtiTagHashmap of a preferred size and optionally a load factor. 261 // The preferred size is rounded down to an actual size. 262 JvmtiTagHashmap(int size, float load_factor=0.0f) { 263 int i=0; 264 while (_sizes[i] < size) { 265 if (_sizes[i] < 0) { 266 assert(i > 0, "sanity check"); 267 i--; 268 break; 269 } 270 i++; 271 } 272 273 // if a load factor is specified then use it, otherwise use default 274 if (load_factor > 0.01f) { 275 init(i, load_factor); 276 } else { 277 init(i); 278 } 279 } 280 281 // create a JvmtiTagHashmap with default settings 282 JvmtiTagHashmap() { 283 init(); 284 } 285 286 // release table when JvmtiTagHashmap destroyed 287 ~JvmtiTagHashmap() { 288 if (_table != NULL) { 289 os::free((void*)_table); 290 _table = NULL; 291 } 292 } 293 294 // accessors 295 int size() const { return _size; } 296 JvmtiTagHashmapEntry** table() const { return _table; } 297 int entry_count() const { return _entry_count; } 298 299 // find an entry in the hashmap, returns NULL if not found. 300 inline JvmtiTagHashmapEntry* find(oop key) { 301 unsigned int h = hash(key); 302 JvmtiTagHashmapEntry* entry = _table[h]; 303 while (entry != NULL) { 304 if (entry->object() == key) { 305 return entry; 306 } 307 entry = entry->next(); 308 } 309 return NULL; 310 } 311 312 313 // add a new entry to hashmap 314 inline void add(oop key, JvmtiTagHashmapEntry* entry) { 315 assert(key != NULL, "checking"); 316 assert(find(key) == NULL, "duplicate detected"); 317 unsigned int h = hash(key); 318 JvmtiTagHashmapEntry* anchor = _table[h]; 319 if (anchor == NULL) { 320 _table[h] = entry; 321 entry->set_next(NULL); 322 } else { 323 entry->set_next(anchor); 324 _table[h] = entry; 325 } 326 327 _entry_count++; 328 if (trace_threshold() > 0 && entry_count() >= trace_threshold()) { 329 assert(TraceJVMTIObjectTagging, "should only get here when tracing"); 330 print_memory_usage(); 331 compute_next_trace_threshold(); 332 } 333 334 // if the number of entries exceed the threshold then resize 335 if (entry_count() > resize_threshold() && is_resizing_enabled()) { 336 resize(); 337 } 338 } 339 340 // remove an entry with the given key. 341 inline JvmtiTagHashmapEntry* remove(oop key) { 342 unsigned int h = hash(key); 343 JvmtiTagHashmapEntry* entry = _table[h]; 344 JvmtiTagHashmapEntry* prev = NULL; 345 while (entry != NULL) { 346 if (key == entry->object()) { 347 break; 348 } 349 prev = entry; 350 entry = entry->next(); 351 } 352 if (entry != NULL) { 353 remove(prev, h, entry); 354 } 355 return entry; 356 } 357 358 // iterate over all entries in the hashmap 359 void entry_iterate(JvmtiTagHashmapEntryClosure* closure); 360 }; 361 362 // possible hashmap sizes - odd primes that roughly double in size. 363 // To avoid excessive resizing the odd primes from 4801-76831 and 364 // 76831-307261 have been removed. The list must be terminated by -1. 365 int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891, 366 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 }; 367 368 369 // A supporting class for iterating over all entries in Hashmap 370 class JvmtiTagHashmapEntryClosure { 371 public: 372 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0; 373 }; 374 375 376 // iterate over all entries in the hashmap 377 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) { 378 for (int i=0; i<_size; i++) { 379 JvmtiTagHashmapEntry* entry = _table[i]; 380 JvmtiTagHashmapEntry* prev = NULL; 381 while (entry != NULL) { 382 // obtain the next entry before invoking do_entry - this is 383 // necessary because do_entry may remove the entry from the 384 // hashmap. 385 JvmtiTagHashmapEntry* next = entry->next(); 386 closure->do_entry(entry); 387 entry = next; 388 } 389 } 390 } 391 392 // debugging 393 void JvmtiTagHashmap::print_memory_usage() { 394 intptr_t p = (intptr_t)this; 395 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p); 396 397 // table + entries in KB 398 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) + 399 entry_count()*sizeof(JvmtiTagHashmapEntry))/K; 400 401 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K); 402 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]", 403 entry_count(), hashmap_usage, weak_globals_usage); 404 } 405 406 // compute threshold for the next trace message 407 void JvmtiTagHashmap::compute_next_trace_threshold() { 408 if (trace_threshold() < medium_trace_threshold) { 409 _trace_threshold += small_trace_threshold; 410 } else { 411 if (trace_threshold() < large_trace_threshold) { 412 _trace_threshold += medium_trace_threshold; 413 } else { 414 _trace_threshold += large_trace_threshold; 415 } 416 } 417 } 418 419 // create a JvmtiTagMap 420 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) : 421 _env(env), 422 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false), 423 _free_entries(NULL), 424 _free_entries_count(0) 425 { 426 assert(JvmtiThreadState_lock->is_locked(), "sanity check"); 427 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment"); 428 429 _hashmap = new JvmtiTagHashmap(); 430 431 // finally add us to the environment 432 ((JvmtiEnvBase *)env)->set_tag_map(this); 433 } 434 435 436 // destroy a JvmtiTagMap 437 JvmtiTagMap::~JvmtiTagMap() { 438 439 // no lock acquired as we assume the enclosing environment is 440 // also being destroryed. 441 ((JvmtiEnvBase *)_env)->set_tag_map(NULL); 442 443 JvmtiTagHashmapEntry** table = _hashmap->table(); 444 for (int j = 0; j < _hashmap->size(); j++) { 445 JvmtiTagHashmapEntry* entry = table[j]; 446 while (entry != NULL) { 447 JvmtiTagHashmapEntry* next = entry->next(); 448 delete entry; 449 entry = next; 450 } 451 } 452 453 // finally destroy the hashmap 454 delete _hashmap; 455 _hashmap = NULL; 456 457 // remove any entries on the free list 458 JvmtiTagHashmapEntry* entry = _free_entries; 459 while (entry != NULL) { 460 JvmtiTagHashmapEntry* next = entry->next(); 461 delete entry; 462 entry = next; 463 } 464 _free_entries = NULL; 465 } 466 467 // create a hashmap entry 468 // - if there's an entry on the (per-environment) free list then this 469 // is returned. Otherwise an new entry is allocated. 470 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) { 471 assert(Thread::current()->is_VM_thread() || is_locked(), "checking"); 472 JvmtiTagHashmapEntry* entry; 473 if (_free_entries == NULL) { 474 entry = new JvmtiTagHashmapEntry(ref, tag); 475 } else { 476 assert(_free_entries_count > 0, "mismatched _free_entries_count"); 477 _free_entries_count--; 478 entry = _free_entries; 479 _free_entries = entry->next(); 480 entry->init(ref, tag); 481 } 482 return entry; 483 } 484 485 // destroy an entry by returning it to the free list 486 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) { 487 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); 488 // limit the size of the free list 489 if (_free_entries_count >= max_free_entries) { 490 delete entry; 491 } else { 492 entry->set_next(_free_entries); 493 _free_entries = entry; 494 _free_entries_count++; 495 } 496 } 497 498 // returns the tag map for the given environments. If the tag map 499 // doesn't exist then it is created. 500 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) { 501 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map(); 502 if (tag_map == NULL) { 503 MutexLocker mu(JvmtiThreadState_lock); 504 tag_map = ((JvmtiEnvBase*)env)->tag_map(); 505 if (tag_map == NULL) { 506 tag_map = new JvmtiTagMap(env); 507 } 508 } else { 509 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); 510 } 511 return tag_map; 512 } 513 514 // iterate over all entries in the tag map. 515 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) { 516 hashmap()->entry_iterate(closure); 517 } 518 519 // returns true if the hashmaps are empty 520 bool JvmtiTagMap::is_empty() { 521 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); 522 return hashmap()->entry_count() == 0; 523 } 524 525 526 // Return the tag value for an object, or 0 if the object is 527 // not tagged 528 // 529 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) { 530 JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o); 531 if (entry == NULL) { 532 return 0; 533 } else { 534 return entry->tag(); 535 } 536 } 537 538 539 // A CallbackWrapper is a support class for querying and tagging an object 540 // around a callback to a profiler. The constructor does pre-callback 541 // work to get the tag value, klass tag value, ... and the destructor 542 // does the post-callback work of tagging or untagging the object. 543 // 544 // { 545 // CallbackWrapper wrapper(tag_map, o); 546 // 547 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...) 548 // 549 // } // wrapper goes out of scope here which results in the destructor 550 // checking to see if the object has been tagged, untagged, or the 551 // tag value has changed. 552 // 553 class CallbackWrapper : public StackObj { 554 private: 555 JvmtiTagMap* _tag_map; 556 JvmtiTagHashmap* _hashmap; 557 JvmtiTagHashmapEntry* _entry; 558 oop _o; 559 jlong _obj_size; 560 jlong _obj_tag; 561 jlong _klass_tag; 562 563 protected: 564 JvmtiTagMap* tag_map() const { return _tag_map; } 565 566 // invoked post-callback to tag, untag, or update the tag of an object 567 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap, 568 JvmtiTagHashmapEntry* entry, jlong obj_tag); 569 public: 570 CallbackWrapper(JvmtiTagMap* tag_map, oop o) { 571 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(), 572 "MT unsafe or must be VM thread"); 573 574 // object to tag 575 _o = o; 576 577 // object size 578 _obj_size = (jlong)_o->size() * wordSize; 579 580 // record the context 581 _tag_map = tag_map; 582 _hashmap = tag_map->hashmap(); 583 _entry = _hashmap->find(_o); 584 585 // get object tag 586 _obj_tag = (_entry == NULL) ? 0 : _entry->tag(); 587 588 // get the class and the class's tag value 589 assert(SystemDictionary::Class_klass()->oop_is_instanceMirror(), "Is not?"); 590 591 _klass_tag = tag_for(tag_map, _o->klass()->java_mirror()); 592 } 593 594 ~CallbackWrapper() { 595 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag); 596 } 597 598 inline jlong* obj_tag_p() { return &_obj_tag; } 599 inline jlong obj_size() const { return _obj_size; } 600 inline jlong obj_tag() const { return _obj_tag; } 601 inline jlong klass_tag() const { return _klass_tag; } 602 }; 603 604 605 606 // callback post-callback to tag, untag, or update the tag of an object 607 void inline CallbackWrapper::post_callback_tag_update(oop o, 608 JvmtiTagHashmap* hashmap, 609 JvmtiTagHashmapEntry* entry, 610 jlong obj_tag) { 611 if (entry == NULL) { 612 if (obj_tag != 0) { 613 // callback has tagged the object 614 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 615 entry = tag_map()->create_entry(o, obj_tag); 616 hashmap->add(o, entry); 617 } 618 } else { 619 // object was previously tagged - the callback may have untagged 620 // the object or changed the tag value 621 if (obj_tag == 0) { 622 623 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o); 624 assert(entry_removed == entry, "checking"); 625 tag_map()->destroy_entry(entry); 626 627 } else { 628 if (obj_tag != entry->tag()) { 629 entry->set_tag(obj_tag); 630 } 631 } 632 } 633 } 634 635 // An extended CallbackWrapper used when reporting an object reference 636 // to the agent. 637 // 638 // { 639 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o); 640 // 641 // (*callback)(wrapper.klass_tag(), 642 // wrapper.obj_size(), 643 // wrapper.obj_tag_p() 644 // wrapper.referrer_tag_p(), ...) 645 // 646 // } // wrapper goes out of scope here which results in the destructor 647 // checking to see if the referrer object has been tagged, untagged, 648 // or the tag value has changed. 649 // 650 class TwoOopCallbackWrapper : public CallbackWrapper { 651 private: 652 bool _is_reference_to_self; 653 JvmtiTagHashmap* _referrer_hashmap; 654 JvmtiTagHashmapEntry* _referrer_entry; 655 oop _referrer; 656 jlong _referrer_obj_tag; 657 jlong _referrer_klass_tag; 658 jlong* _referrer_tag_p; 659 660 bool is_reference_to_self() const { return _is_reference_to_self; } 661 662 public: 663 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) : 664 CallbackWrapper(tag_map, o) 665 { 666 // self reference needs to be handled in a special way 667 _is_reference_to_self = (referrer == o); 668 669 if (_is_reference_to_self) { 670 _referrer_klass_tag = klass_tag(); 671 _referrer_tag_p = obj_tag_p(); 672 } else { 673 _referrer = referrer; 674 // record the context 675 _referrer_hashmap = tag_map->hashmap(); 676 _referrer_entry = _referrer_hashmap->find(_referrer); 677 678 // get object tag 679 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag(); 680 _referrer_tag_p = &_referrer_obj_tag; 681 682 // get referrer class tag. 683 _referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror()); 684 } 685 } 686 687 ~TwoOopCallbackWrapper() { 688 if (!is_reference_to_self()){ 689 post_callback_tag_update(_referrer, 690 _referrer_hashmap, 691 _referrer_entry, 692 _referrer_obj_tag); 693 } 694 } 695 696 // address of referrer tag 697 // (for a self reference this will return the same thing as obj_tag_p()) 698 inline jlong* referrer_tag_p() { return _referrer_tag_p; } 699 700 // referrer's class tag 701 inline jlong referrer_klass_tag() { return _referrer_klass_tag; } 702 }; 703 704 // tag an object 705 // 706 // This function is performance critical. If many threads attempt to tag objects 707 // around the same time then it's possible that the Mutex associated with the 708 // tag map will be a hot lock. 709 void JvmtiTagMap::set_tag(jobject object, jlong tag) { 710 MutexLocker ml(lock()); 711 712 // resolve the object 713 oop o = JNIHandles::resolve_non_null(object); 714 715 // see if the object is already tagged 716 JvmtiTagHashmap* hashmap = _hashmap; 717 JvmtiTagHashmapEntry* entry = hashmap->find(o); 718 719 // if the object is not already tagged then we tag it 720 if (entry == NULL) { 721 if (tag != 0) { 722 entry = create_entry(o, tag); 723 hashmap->add(o, entry); 724 } else { 725 // no-op 726 } 727 } else { 728 // if the object is already tagged then we either update 729 // the tag (if a new tag value has been provided) 730 // or remove the object if the new tag value is 0. 731 if (tag == 0) { 732 hashmap->remove(o); 733 destroy_entry(entry); 734 } else { 735 entry->set_tag(tag); 736 } 737 } 738 } 739 740 // get the tag for an object 741 jlong JvmtiTagMap::get_tag(jobject object) { 742 MutexLocker ml(lock()); 743 744 // resolve the object 745 oop o = JNIHandles::resolve_non_null(object); 746 747 return tag_for(this, o); 748 } 749 750 751 // Helper class used to describe the static or instance fields of a class. 752 // For each field it holds the field index (as defined by the JVMTI specification), 753 // the field type, and the offset. 754 755 class ClassFieldDescriptor: public CHeapObj<mtInternal> { 756 private: 757 int _field_index; 758 int _field_offset; 759 char _field_type; 760 public: 761 ClassFieldDescriptor(int index, char type, int offset) : 762 _field_index(index), _field_type(type), _field_offset(offset) { 763 } 764 int field_index() const { return _field_index; } 765 char field_type() const { return _field_type; } 766 int field_offset() const { return _field_offset; } 767 }; 768 769 class ClassFieldMap: public CHeapObj<mtInternal> { 770 private: 771 enum { 772 initial_field_count = 5 773 }; 774 775 // list of field descriptors 776 GrowableArray<ClassFieldDescriptor*>* _fields; 777 778 // constructor 779 ClassFieldMap(); 780 781 // add a field 782 void add(int index, char type, int offset); 783 784 // returns the field count for the given class 785 static int compute_field_count(instanceKlassHandle ikh); 786 787 public: 788 ~ClassFieldMap(); 789 790 // access 791 int field_count() { return _fields->length(); } 792 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); } 793 794 // functions to create maps of static or instance fields 795 static ClassFieldMap* create_map_of_static_fields(Klass* k); 796 static ClassFieldMap* create_map_of_instance_fields(oop obj); 797 }; 798 799 ClassFieldMap::ClassFieldMap() { 800 _fields = new (ResourceObj::C_HEAP, mtInternal) 801 GrowableArray<ClassFieldDescriptor*>(initial_field_count, true); 802 } 803 804 ClassFieldMap::~ClassFieldMap() { 805 for (int i=0; i<_fields->length(); i++) { 806 delete _fields->at(i); 807 } 808 delete _fields; 809 } 810 811 void ClassFieldMap::add(int index, char type, int offset) { 812 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset); 813 _fields->append(field); 814 } 815 816 // Returns a heap allocated ClassFieldMap to describe the static fields 817 // of the given class. 818 // 819 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) { 820 HandleMark hm; 821 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k); 822 823 // create the field map 824 ClassFieldMap* field_map = new ClassFieldMap(); 825 826 FilteredFieldStream f(ikh, false, false); 827 int max_field_index = f.field_count()-1; 828 829 int index = 0; 830 for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) { 831 // ignore instance fields 832 if (!fld.access_flags().is_static()) { 833 continue; 834 } 835 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset()); 836 } 837 return field_map; 838 } 839 840 // Returns a heap allocated ClassFieldMap to describe the instance fields 841 // of the given class. All instance fields are included (this means public 842 // and private fields declared in superclasses and superinterfaces too). 843 // 844 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) { 845 HandleMark hm; 846 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass()); 847 848 // create the field map 849 ClassFieldMap* field_map = new ClassFieldMap(); 850 851 FilteredFieldStream f(ikh, false, false); 852 853 int max_field_index = f.field_count()-1; 854 855 int index = 0; 856 for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) { 857 // ignore static fields 858 if (fld.access_flags().is_static()) { 859 continue; 860 } 861 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset()); 862 } 863 864 return field_map; 865 } 866 867 // Helper class used to cache a ClassFileMap for the instance fields of 868 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during 869 // heap iteration and avoid creating a field map for each object in the heap 870 // (only need to create the map when the first instance of a class is encountered). 871 // 872 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> { 873 private: 874 enum { 875 initial_class_count = 200 876 }; 877 ClassFieldMap* _field_map; 878 879 ClassFieldMap* field_map() const { return _field_map; } 880 881 JvmtiCachedClassFieldMap(ClassFieldMap* field_map); 882 ~JvmtiCachedClassFieldMap(); 883 884 static GrowableArray<InstanceKlass*>* _class_list; 885 static void add_to_class_list(InstanceKlass* ik); 886 887 public: 888 // returns the field map for a given object (returning map cached 889 // by InstanceKlass if possible 890 static ClassFieldMap* get_map_of_instance_fields(oop obj); 891 892 // removes the field map from all instanceKlasses - should be 893 // called before VM operation completes 894 static void clear_cache(); 895 896 // returns the number of ClassFieldMap cached by instanceKlasses 897 static int cached_field_map_count(); 898 }; 899 900 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list; 901 902 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) { 903 _field_map = field_map; 904 } 905 906 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() { 907 if (_field_map != NULL) { 908 delete _field_map; 909 } 910 } 911 912 // Marker class to ensure that the class file map cache is only used in a defined 913 // scope. 914 class ClassFieldMapCacheMark : public StackObj { 915 private: 916 static bool _is_active; 917 public: 918 ClassFieldMapCacheMark() { 919 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 920 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty"); 921 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested"); 922 _is_active = true; 923 } 924 ~ClassFieldMapCacheMark() { 925 JvmtiCachedClassFieldMap::clear_cache(); 926 _is_active = false; 927 } 928 static bool is_active() { return _is_active; } 929 }; 930 931 bool ClassFieldMapCacheMark::_is_active; 932 933 934 // record that the given InstanceKlass is caching a field map 935 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) { 936 if (_class_list == NULL) { 937 _class_list = new (ResourceObj::C_HEAP, mtInternal) 938 GrowableArray<InstanceKlass*>(initial_class_count, true); 939 } 940 _class_list->push(ik); 941 } 942 943 // returns the instance field map for the given object 944 // (returns field map cached by the InstanceKlass if possible) 945 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) { 946 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 947 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active"); 948 949 Klass* k = obj->klass(); 950 InstanceKlass* ik = InstanceKlass::cast(k); 951 952 // return cached map if possible 953 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); 954 if (cached_map != NULL) { 955 assert(cached_map->field_map() != NULL, "missing field list"); 956 return cached_map->field_map(); 957 } else { 958 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj); 959 cached_map = new JvmtiCachedClassFieldMap(field_map); 960 ik->set_jvmti_cached_class_field_map(cached_map); 961 add_to_class_list(ik); 962 return field_map; 963 } 964 } 965 966 // remove the fields maps cached from all instanceKlasses 967 void JvmtiCachedClassFieldMap::clear_cache() { 968 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 969 if (_class_list != NULL) { 970 for (int i = 0; i < _class_list->length(); i++) { 971 InstanceKlass* ik = _class_list->at(i); 972 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); 973 assert(cached_map != NULL, "should not be NULL"); 974 ik->set_jvmti_cached_class_field_map(NULL); 975 delete cached_map; // deletes the encapsulated field map 976 } 977 delete _class_list; 978 _class_list = NULL; 979 } 980 } 981 982 // returns the number of ClassFieldMap cached by instanceKlasses 983 int JvmtiCachedClassFieldMap::cached_field_map_count() { 984 return (_class_list == NULL) ? 0 : _class_list->length(); 985 } 986 987 // helper function to indicate if an object is filtered by its tag or class tag 988 static inline bool is_filtered_by_heap_filter(jlong obj_tag, 989 jlong klass_tag, 990 int heap_filter) { 991 // apply the heap filter 992 if (obj_tag != 0) { 993 // filter out tagged objects 994 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true; 995 } else { 996 // filter out untagged objects 997 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true; 998 } 999 if (klass_tag != 0) { 1000 // filter out objects with tagged classes 1001 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true; 1002 } else { 1003 // filter out objects with untagged classes. 1004 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true; 1005 } 1006 return false; 1007 } 1008 1009 // helper function to indicate if an object is filtered by a klass filter 1010 static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) { 1011 if (!klass_filter.is_null()) { 1012 if (obj->klass() != klass_filter()) { 1013 return true; 1014 } 1015 } 1016 return false; 1017 } 1018 1019 // helper function to tell if a field is a primitive field or not 1020 static inline bool is_primitive_field_type(char type) { 1021 return (type != 'L' && type != '['); 1022 } 1023 1024 // helper function to copy the value from location addr to jvalue. 1025 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) { 1026 switch (value_type) { 1027 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; } 1028 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; } 1029 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; } 1030 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; } 1031 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; } 1032 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; } 1033 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; } 1034 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; } 1035 default: ShouldNotReachHere(); 1036 } 1037 } 1038 1039 // helper function to invoke string primitive value callback 1040 // returns visit control flags 1041 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb, 1042 CallbackWrapper* wrapper, 1043 oop str, 1044 void* user_data) 1045 { 1046 assert(str->klass() == SystemDictionary::String_klass(), "not a string"); 1047 1048 // get the string value and length 1049 // (string value may be offset from the base) 1050 int s_len = java_lang_String::length(str); 1051 typeArrayOop s_value = java_lang_String::value(str); 1052 int s_offset = java_lang_String::offset(str); 1053 jchar* value; 1054 if (s_len > 0) { 1055 value = s_value->char_at_addr(s_offset); 1056 } else { 1057 value = (jchar*) s_value->base(T_CHAR); 1058 } 1059 1060 // invoke the callback 1061 return (*cb)(wrapper->klass_tag(), 1062 wrapper->obj_size(), 1063 wrapper->obj_tag_p(), 1064 value, 1065 (jint)s_len, 1066 user_data); 1067 } 1068 1069 // helper function to invoke string primitive value callback 1070 // returns visit control flags 1071 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb, 1072 CallbackWrapper* wrapper, 1073 oop obj, 1074 void* user_data) 1075 { 1076 assert(obj->is_typeArray(), "not a primitive array"); 1077 1078 // get base address of first element 1079 typeArrayOop array = typeArrayOop(obj); 1080 BasicType type = TypeArrayKlass::cast(array->klass())->element_type(); 1081 void* elements = array->base(type); 1082 1083 // jvmtiPrimitiveType is defined so this mapping is always correct 1084 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type); 1085 1086 return (*cb)(wrapper->klass_tag(), 1087 wrapper->obj_size(), 1088 wrapper->obj_tag_p(), 1089 (jint)array->length(), 1090 elem_type, 1091 elements, 1092 user_data); 1093 } 1094 1095 // helper function to invoke the primitive field callback for all static fields 1096 // of a given class 1097 static jint invoke_primitive_field_callback_for_static_fields 1098 (CallbackWrapper* wrapper, 1099 oop obj, 1100 jvmtiPrimitiveFieldCallback cb, 1101 void* user_data) 1102 { 1103 // for static fields only the index will be set 1104 static jvmtiHeapReferenceInfo reference_info = { 0 }; 1105 1106 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class"); 1107 if (java_lang_Class::is_primitive(obj)) { 1108 return 0; 1109 } 1110 Klass* klass = java_lang_Class::as_Klass(obj); 1111 1112 // ignore classes for object and type arrays 1113 if (!klass->oop_is_instance()) { 1114 return 0; 1115 } 1116 1117 // ignore classes which aren't linked yet 1118 InstanceKlass* ik = InstanceKlass::cast(klass); 1119 if (!ik->is_linked()) { 1120 return 0; 1121 } 1122 1123 // get the field map 1124 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass); 1125 1126 // invoke the callback for each static primitive field 1127 for (int i=0; i<field_map->field_count(); i++) { 1128 ClassFieldDescriptor* field = field_map->field_at(i); 1129 1130 // ignore non-primitive fields 1131 char type = field->field_type(); 1132 if (!is_primitive_field_type(type)) { 1133 continue; 1134 } 1135 // one-to-one mapping 1136 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 1137 1138 // get offset and field value 1139 int offset = field->field_offset(); 1140 address addr = (address)klass->java_mirror() + offset; 1141 jvalue value; 1142 copy_to_jvalue(&value, addr, value_type); 1143 1144 // field index 1145 reference_info.field.index = field->field_index(); 1146 1147 // invoke the callback 1148 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD, 1149 &reference_info, 1150 wrapper->klass_tag(), 1151 wrapper->obj_tag_p(), 1152 value, 1153 value_type, 1154 user_data); 1155 if (res & JVMTI_VISIT_ABORT) { 1156 delete field_map; 1157 return res; 1158 } 1159 } 1160 1161 delete field_map; 1162 return 0; 1163 } 1164 1165 // helper function to invoke the primitive field callback for all instance fields 1166 // of a given object 1167 static jint invoke_primitive_field_callback_for_instance_fields( 1168 CallbackWrapper* wrapper, 1169 oop obj, 1170 jvmtiPrimitiveFieldCallback cb, 1171 void* user_data) 1172 { 1173 // for instance fields only the index will be set 1174 static jvmtiHeapReferenceInfo reference_info = { 0 }; 1175 1176 // get the map of the instance fields 1177 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj); 1178 1179 // invoke the callback for each instance primitive field 1180 for (int i=0; i<fields->field_count(); i++) { 1181 ClassFieldDescriptor* field = fields->field_at(i); 1182 1183 // ignore non-primitive fields 1184 char type = field->field_type(); 1185 if (!is_primitive_field_type(type)) { 1186 continue; 1187 } 1188 // one-to-one mapping 1189 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 1190 1191 // get offset and field value 1192 int offset = field->field_offset(); 1193 address addr = (address)obj + offset; 1194 jvalue value; 1195 copy_to_jvalue(&value, addr, value_type); 1196 1197 // field index 1198 reference_info.field.index = field->field_index(); 1199 1200 // invoke the callback 1201 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD, 1202 &reference_info, 1203 wrapper->klass_tag(), 1204 wrapper->obj_tag_p(), 1205 value, 1206 value_type, 1207 user_data); 1208 if (res & JVMTI_VISIT_ABORT) { 1209 return res; 1210 } 1211 } 1212 return 0; 1213 } 1214 1215 1216 // VM operation to iterate over all objects in the heap (both reachable 1217 // and unreachable) 1218 class VM_HeapIterateOperation: public VM_Operation { 1219 private: 1220 ObjectClosure* _blk; 1221 public: 1222 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; } 1223 1224 VMOp_Type type() const { return VMOp_HeapIterateOperation; } 1225 void doit() { 1226 // allows class files maps to be cached during iteration 1227 ClassFieldMapCacheMark cm; 1228 1229 // make sure that heap is parsable (fills TLABs with filler objects) 1230 Universe::heap()->ensure_parsability(false); // no need to retire TLABs 1231 1232 // Verify heap before iteration - if the heap gets corrupted then 1233 // JVMTI's IterateOverHeap will crash. 1234 if (VerifyBeforeIteration) { 1235 Universe::verify(); 1236 } 1237 1238 // do the iteration 1239 // If this operation encounters a bad object when using CMS, 1240 // consider using safe_object_iterate() which avoids perm gen 1241 // objects that may contain bad references. 1242 Universe::heap()->object_iterate(_blk); 1243 } 1244 1245 }; 1246 1247 1248 // An ObjectClosure used to support the deprecated IterateOverHeap and 1249 // IterateOverInstancesOfClass functions 1250 class IterateOverHeapObjectClosure: public ObjectClosure { 1251 private: 1252 JvmtiTagMap* _tag_map; 1253 KlassHandle _klass; 1254 jvmtiHeapObjectFilter _object_filter; 1255 jvmtiHeapObjectCallback _heap_object_callback; 1256 const void* _user_data; 1257 1258 // accessors 1259 JvmtiTagMap* tag_map() const { return _tag_map; } 1260 jvmtiHeapObjectFilter object_filter() const { return _object_filter; } 1261 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; } 1262 KlassHandle klass() const { return _klass; } 1263 const void* user_data() const { return _user_data; } 1264 1265 // indicates if iteration has been aborted 1266 bool _iteration_aborted; 1267 bool is_iteration_aborted() const { return _iteration_aborted; } 1268 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; } 1269 1270 public: 1271 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map, 1272 KlassHandle klass, 1273 jvmtiHeapObjectFilter object_filter, 1274 jvmtiHeapObjectCallback heap_object_callback, 1275 const void* user_data) : 1276 _tag_map(tag_map), 1277 _klass(klass), 1278 _object_filter(object_filter), 1279 _heap_object_callback(heap_object_callback), 1280 _user_data(user_data), 1281 _iteration_aborted(false) 1282 { 1283 } 1284 1285 void do_object(oop o); 1286 }; 1287 1288 // invoked for each object in the heap 1289 void IterateOverHeapObjectClosure::do_object(oop o) { 1290 // check if iteration has been halted 1291 if (is_iteration_aborted()) return; 1292 1293 // ignore any objects that aren't visible to profiler 1294 if (!ServiceUtil::visible_oop(o)) return; 1295 1296 // instanceof check when filtering by klass 1297 if (!klass().is_null() && !o->is_a(klass()())) { 1298 return; 1299 } 1300 // prepare for the calllback 1301 CallbackWrapper wrapper(tag_map(), o); 1302 1303 // if the object is tagged and we're only interested in untagged objects 1304 // then don't invoke the callback. Similiarly, if the object is untagged 1305 // and we're only interested in tagged objects we skip the callback. 1306 if (wrapper.obj_tag() != 0) { 1307 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return; 1308 } else { 1309 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return; 1310 } 1311 1312 // invoke the agent's callback 1313 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(), 1314 wrapper.obj_size(), 1315 wrapper.obj_tag_p(), 1316 (void*)user_data()); 1317 if (control == JVMTI_ITERATION_ABORT) { 1318 set_iteration_aborted(true); 1319 } 1320 } 1321 1322 // An ObjectClosure used to support the IterateThroughHeap function 1323 class IterateThroughHeapObjectClosure: public ObjectClosure { 1324 private: 1325 JvmtiTagMap* _tag_map; 1326 KlassHandle _klass; 1327 int _heap_filter; 1328 const jvmtiHeapCallbacks* _callbacks; 1329 const void* _user_data; 1330 1331 // accessor functions 1332 JvmtiTagMap* tag_map() const { return _tag_map; } 1333 int heap_filter() const { return _heap_filter; } 1334 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; } 1335 KlassHandle klass() const { return _klass; } 1336 const void* user_data() const { return _user_data; } 1337 1338 // indicates if the iteration has been aborted 1339 bool _iteration_aborted; 1340 bool is_iteration_aborted() const { return _iteration_aborted; } 1341 1342 // used to check the visit control flags. If the abort flag is set 1343 // then we set the iteration aborted flag so that the iteration completes 1344 // without processing any further objects 1345 bool check_flags_for_abort(jint flags) { 1346 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0; 1347 if (is_abort) { 1348 _iteration_aborted = true; 1349 } 1350 return is_abort; 1351 } 1352 1353 public: 1354 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map, 1355 KlassHandle klass, 1356 int heap_filter, 1357 const jvmtiHeapCallbacks* heap_callbacks, 1358 const void* user_data) : 1359 _tag_map(tag_map), 1360 _klass(klass), 1361 _heap_filter(heap_filter), 1362 _callbacks(heap_callbacks), 1363 _user_data(user_data), 1364 _iteration_aborted(false) 1365 { 1366 } 1367 1368 void do_object(oop o); 1369 }; 1370 1371 // invoked for each object in the heap 1372 void IterateThroughHeapObjectClosure::do_object(oop obj) { 1373 // check if iteration has been halted 1374 if (is_iteration_aborted()) return; 1375 1376 // ignore any objects that aren't visible to profiler 1377 if (!ServiceUtil::visible_oop(obj)) return; 1378 1379 // apply class filter 1380 if (is_filtered_by_klass_filter(obj, klass())) return; 1381 1382 // prepare for callback 1383 CallbackWrapper wrapper(tag_map(), obj); 1384 1385 // check if filtered by the heap filter 1386 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) { 1387 return; 1388 } 1389 1390 // for arrays we need the length, otherwise -1 1391 bool is_array = obj->is_array(); 1392 int len = is_array ? arrayOop(obj)->length() : -1; 1393 1394 // invoke the object callback (if callback is provided) 1395 if (callbacks()->heap_iteration_callback != NULL) { 1396 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback; 1397 jint res = (*cb)(wrapper.klass_tag(), 1398 wrapper.obj_size(), 1399 wrapper.obj_tag_p(), 1400 (jint)len, 1401 (void*)user_data()); 1402 if (check_flags_for_abort(res)) return; 1403 } 1404 1405 // for objects and classes we report primitive fields if callback provided 1406 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) { 1407 jint res; 1408 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback; 1409 if (obj->klass() == SystemDictionary::Class_klass()) { 1410 res = invoke_primitive_field_callback_for_static_fields(&wrapper, 1411 obj, 1412 cb, 1413 (void*)user_data()); 1414 } else { 1415 res = invoke_primitive_field_callback_for_instance_fields(&wrapper, 1416 obj, 1417 cb, 1418 (void*)user_data()); 1419 } 1420 if (check_flags_for_abort(res)) return; 1421 } 1422 1423 // string callback 1424 if (!is_array && 1425 callbacks()->string_primitive_value_callback != NULL && 1426 obj->klass() == SystemDictionary::String_klass()) { 1427 jint res = invoke_string_value_callback( 1428 callbacks()->string_primitive_value_callback, 1429 &wrapper, 1430 obj, 1431 (void*)user_data() ); 1432 if (check_flags_for_abort(res)) return; 1433 } 1434 1435 // array callback 1436 if (is_array && 1437 callbacks()->array_primitive_value_callback != NULL && 1438 obj->is_typeArray()) { 1439 jint res = invoke_array_primitive_value_callback( 1440 callbacks()->array_primitive_value_callback, 1441 &wrapper, 1442 obj, 1443 (void*)user_data() ); 1444 if (check_flags_for_abort(res)) return; 1445 } 1446 }; 1447 1448 1449 // Deprecated function to iterate over all objects in the heap 1450 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter, 1451 KlassHandle klass, 1452 jvmtiHeapObjectCallback heap_object_callback, 1453 const void* user_data) 1454 { 1455 MutexLocker ml(Heap_lock); 1456 IterateOverHeapObjectClosure blk(this, 1457 klass, 1458 object_filter, 1459 heap_object_callback, 1460 user_data); 1461 VM_HeapIterateOperation op(&blk); 1462 VMThread::execute(&op); 1463 } 1464 1465 1466 // Iterates over all objects in the heap 1467 void JvmtiTagMap::iterate_through_heap(jint heap_filter, 1468 KlassHandle klass, 1469 const jvmtiHeapCallbacks* callbacks, 1470 const void* user_data) 1471 { 1472 MutexLocker ml(Heap_lock); 1473 IterateThroughHeapObjectClosure blk(this, 1474 klass, 1475 heap_filter, 1476 callbacks, 1477 user_data); 1478 VM_HeapIterateOperation op(&blk); 1479 VMThread::execute(&op); 1480 } 1481 1482 // support class for get_objects_with_tags 1483 1484 class TagObjectCollector : public JvmtiTagHashmapEntryClosure { 1485 private: 1486 JvmtiEnv* _env; 1487 jlong* _tags; 1488 jint _tag_count; 1489 1490 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs) 1491 GrowableArray<uint64_t>* _tag_results; // collected tags 1492 1493 public: 1494 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) { 1495 _env = env; 1496 _tags = (jlong*)tags; 1497 _tag_count = tag_count; 1498 _object_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<jobject>(1,true); 1499 _tag_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<uint64_t>(1,true); 1500 } 1501 1502 ~TagObjectCollector() { 1503 delete _object_results; 1504 delete _tag_results; 1505 } 1506 1507 // for each tagged object check if the tag value matches 1508 // - if it matches then we create a JNI local reference to the object 1509 // and record the reference and tag value. 1510 // 1511 void do_entry(JvmtiTagHashmapEntry* entry) { 1512 for (int i=0; i<_tag_count; i++) { 1513 if (_tags[i] == entry->tag()) { 1514 oop o = entry->object(); 1515 assert(o != NULL && Universe::heap()->is_in_reserved(o), "sanity check"); 1516 jobject ref = JNIHandles::make_local(JavaThread::current(), o); 1517 _object_results->append(ref); 1518 _tag_results->append((uint64_t)entry->tag()); 1519 } 1520 } 1521 } 1522 1523 // return the results from the collection 1524 // 1525 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { 1526 jvmtiError error; 1527 int count = _object_results->length(); 1528 assert(count >= 0, "sanity check"); 1529 1530 // if object_result_ptr is not NULL then allocate the result and copy 1531 // in the object references. 1532 if (object_result_ptr != NULL) { 1533 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr); 1534 if (error != JVMTI_ERROR_NONE) { 1535 return error; 1536 } 1537 for (int i=0; i<count; i++) { 1538 (*object_result_ptr)[i] = _object_results->at(i); 1539 } 1540 } 1541 1542 // if tag_result_ptr is not NULL then allocate the result and copy 1543 // in the tag values. 1544 if (tag_result_ptr != NULL) { 1545 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr); 1546 if (error != JVMTI_ERROR_NONE) { 1547 if (object_result_ptr != NULL) { 1548 _env->Deallocate((unsigned char*)object_result_ptr); 1549 } 1550 return error; 1551 } 1552 for (int i=0; i<count; i++) { 1553 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i); 1554 } 1555 } 1556 1557 *count_ptr = count; 1558 return JVMTI_ERROR_NONE; 1559 } 1560 }; 1561 1562 // return the list of objects with the specified tags 1563 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags, 1564 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { 1565 1566 TagObjectCollector collector(env(), tags, count); 1567 { 1568 // iterate over all tagged objects 1569 MutexLocker ml(lock()); 1570 entry_iterate(&collector); 1571 } 1572 return collector.result(count_ptr, object_result_ptr, tag_result_ptr); 1573 } 1574 1575 1576 // ObjectMarker is used to support the marking objects when walking the 1577 // heap. 1578 // 1579 // This implementation uses the existing mark bits in an object for 1580 // marking. Objects that are marked must later have their headers restored. 1581 // As most objects are unlocked and don't have their identity hash computed 1582 // we don't have to save their headers. Instead we save the headers that 1583 // are "interesting". Later when the headers are restored this implementation 1584 // restores all headers to their initial value and then restores the few 1585 // objects that had interesting headers. 1586 // 1587 // Future work: This implementation currently uses growable arrays to save 1588 // the oop and header of interesting objects. As an optimization we could 1589 // use the same technique as the GC and make use of the unused area 1590 // between top() and end(). 1591 // 1592 1593 // An ObjectClosure used to restore the mark bits of an object 1594 class RestoreMarksClosure : public ObjectClosure { 1595 public: 1596 void do_object(oop o) { 1597 if (o != NULL) { 1598 markOop mark = o->mark(); 1599 if (mark->is_marked()) { 1600 o->init_mark(); 1601 } 1602 } 1603 } 1604 }; 1605 1606 // ObjectMarker provides the mark and visited functions 1607 class ObjectMarker : AllStatic { 1608 private: 1609 // saved headers 1610 static GrowableArray<oop>* _saved_oop_stack; 1611 static GrowableArray<markOop>* _saved_mark_stack; 1612 static bool _needs_reset; // do we need to reset mark bits? 1613 1614 public: 1615 static void init(); // initialize 1616 static void done(); // clean-up 1617 1618 static inline void mark(oop o); // mark an object 1619 static inline bool visited(oop o); // check if object has been visited 1620 1621 static inline bool needs_reset() { return _needs_reset; } 1622 static inline void set_needs_reset(bool v) { _needs_reset = v; } 1623 }; 1624 1625 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL; 1626 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL; 1627 bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default 1628 1629 // initialize ObjectMarker - prepares for object marking 1630 void ObjectMarker::init() { 1631 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 1632 1633 // prepare heap for iteration 1634 Universe::heap()->ensure_parsability(false); // no need to retire TLABs 1635 1636 // create stacks for interesting headers 1637 _saved_mark_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<markOop>(4000, true); 1638 _saved_oop_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(4000, true); 1639 1640 if (UseBiasedLocking) { 1641 BiasedLocking::preserve_marks(); 1642 } 1643 } 1644 1645 // Object marking is done so restore object headers 1646 void ObjectMarker::done() { 1647 // iterate over all objects and restore the mark bits to 1648 // their initial value 1649 RestoreMarksClosure blk; 1650 if (needs_reset()) { 1651 Universe::heap()->object_iterate(&blk); 1652 } else { 1653 // We don't need to reset mark bits on this call, but reset the 1654 // flag to the default for the next call. 1655 set_needs_reset(true); 1656 } 1657 1658 // now restore the interesting headers 1659 for (int i = 0; i < _saved_oop_stack->length(); i++) { 1660 oop o = _saved_oop_stack->at(i); 1661 markOop mark = _saved_mark_stack->at(i); 1662 o->set_mark(mark); 1663 } 1664 1665 if (UseBiasedLocking) { 1666 BiasedLocking::restore_marks(); 1667 } 1668 1669 // free the stacks 1670 delete _saved_oop_stack; 1671 delete _saved_mark_stack; 1672 } 1673 1674 // mark an object 1675 inline void ObjectMarker::mark(oop o) { 1676 assert(Universe::heap()->is_in(o), "sanity check"); 1677 assert(!o->mark()->is_marked(), "should only mark an object once"); 1678 1679 // object's mark word 1680 markOop mark = o->mark(); 1681 1682 if (mark->must_be_preserved(o)) { 1683 _saved_mark_stack->push(mark); 1684 _saved_oop_stack->push(o); 1685 } 1686 1687 // mark the object 1688 o->set_mark(markOopDesc::prototype()->set_marked()); 1689 } 1690 1691 // return true if object is marked 1692 inline bool ObjectMarker::visited(oop o) { 1693 return o->mark()->is_marked(); 1694 } 1695 1696 // Stack allocated class to help ensure that ObjectMarker is used 1697 // correctly. Constructor initializes ObjectMarker, destructor calls 1698 // ObjectMarker's done() function to restore object headers. 1699 class ObjectMarkerController : public StackObj { 1700 public: 1701 ObjectMarkerController() { 1702 ObjectMarker::init(); 1703 } 1704 ~ObjectMarkerController() { 1705 ObjectMarker::done(); 1706 } 1707 }; 1708 1709 1710 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind 1711 // (not performance critical as only used for roots) 1712 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) { 1713 switch (kind) { 1714 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL; 1715 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS; 1716 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR; 1717 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL; 1718 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL; 1719 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD; 1720 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER; 1721 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER; 1722 } 1723 } 1724 1725 // Base class for all heap walk contexts. The base class maintains a flag 1726 // to indicate if the context is valid or not. 1727 class HeapWalkContext VALUE_OBJ_CLASS_SPEC { 1728 private: 1729 bool _valid; 1730 public: 1731 HeapWalkContext(bool valid) { _valid = valid; } 1732 void invalidate() { _valid = false; } 1733 bool is_valid() const { return _valid; } 1734 }; 1735 1736 // A basic heap walk context for the deprecated heap walking functions. 1737 // The context for a basic heap walk are the callbacks and fields used by 1738 // the referrer caching scheme. 1739 class BasicHeapWalkContext: public HeapWalkContext { 1740 private: 1741 jvmtiHeapRootCallback _heap_root_callback; 1742 jvmtiStackReferenceCallback _stack_ref_callback; 1743 jvmtiObjectReferenceCallback _object_ref_callback; 1744 1745 // used for caching 1746 oop _last_referrer; 1747 jlong _last_referrer_tag; 1748 1749 public: 1750 BasicHeapWalkContext() : HeapWalkContext(false) { } 1751 1752 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback, 1753 jvmtiStackReferenceCallback stack_ref_callback, 1754 jvmtiObjectReferenceCallback object_ref_callback) : 1755 HeapWalkContext(true), 1756 _heap_root_callback(heap_root_callback), 1757 _stack_ref_callback(stack_ref_callback), 1758 _object_ref_callback(object_ref_callback), 1759 _last_referrer(NULL), 1760 _last_referrer_tag(0) { 1761 } 1762 1763 // accessors 1764 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; } 1765 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; } 1766 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; } 1767 1768 oop last_referrer() const { return _last_referrer; } 1769 void set_last_referrer(oop referrer) { _last_referrer = referrer; } 1770 jlong last_referrer_tag() const { return _last_referrer_tag; } 1771 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; } 1772 }; 1773 1774 // The advanced heap walk context for the FollowReferences functions. 1775 // The context is the callbacks, and the fields used for filtering. 1776 class AdvancedHeapWalkContext: public HeapWalkContext { 1777 private: 1778 jint _heap_filter; 1779 KlassHandle _klass_filter; 1780 const jvmtiHeapCallbacks* _heap_callbacks; 1781 1782 public: 1783 AdvancedHeapWalkContext() : HeapWalkContext(false) { } 1784 1785 AdvancedHeapWalkContext(jint heap_filter, 1786 KlassHandle klass_filter, 1787 const jvmtiHeapCallbacks* heap_callbacks) : 1788 HeapWalkContext(true), 1789 _heap_filter(heap_filter), 1790 _klass_filter(klass_filter), 1791 _heap_callbacks(heap_callbacks) { 1792 } 1793 1794 // accessors 1795 jint heap_filter() const { return _heap_filter; } 1796 KlassHandle klass_filter() const { return _klass_filter; } 1797 1798 const jvmtiHeapReferenceCallback heap_reference_callback() const { 1799 return _heap_callbacks->heap_reference_callback; 1800 }; 1801 const jvmtiPrimitiveFieldCallback primitive_field_callback() const { 1802 return _heap_callbacks->primitive_field_callback; 1803 } 1804 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const { 1805 return _heap_callbacks->array_primitive_value_callback; 1806 } 1807 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const { 1808 return _heap_callbacks->string_primitive_value_callback; 1809 } 1810 }; 1811 1812 // The CallbackInvoker is a class with static functions that the heap walk can call 1813 // into to invoke callbacks. It works in one of two modes. The "basic" mode is 1814 // used for the deprecated IterateOverReachableObjects functions. The "advanced" 1815 // mode is for the newer FollowReferences function which supports a lot of 1816 // additional callbacks. 1817 class CallbackInvoker : AllStatic { 1818 private: 1819 // heap walk styles 1820 enum { basic, advanced }; 1821 static int _heap_walk_type; 1822 static bool is_basic_heap_walk() { return _heap_walk_type == basic; } 1823 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; } 1824 1825 // context for basic style heap walk 1826 static BasicHeapWalkContext _basic_context; 1827 static BasicHeapWalkContext* basic_context() { 1828 assert(_basic_context.is_valid(), "invalid"); 1829 return &_basic_context; 1830 } 1831 1832 // context for advanced style heap walk 1833 static AdvancedHeapWalkContext _advanced_context; 1834 static AdvancedHeapWalkContext* advanced_context() { 1835 assert(_advanced_context.is_valid(), "invalid"); 1836 return &_advanced_context; 1837 } 1838 1839 // context needed for all heap walks 1840 static JvmtiTagMap* _tag_map; 1841 static const void* _user_data; 1842 static GrowableArray<oop>* _visit_stack; 1843 1844 // accessors 1845 static JvmtiTagMap* tag_map() { return _tag_map; } 1846 static const void* user_data() { return _user_data; } 1847 static GrowableArray<oop>* visit_stack() { return _visit_stack; } 1848 1849 // if the object hasn't been visited then push it onto the visit stack 1850 // so that it will be visited later 1851 static inline bool check_for_visit(oop obj) { 1852 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj); 1853 return true; 1854 } 1855 1856 // invoke basic style callbacks 1857 static inline bool invoke_basic_heap_root_callback 1858 (jvmtiHeapRootKind root_kind, oop obj); 1859 static inline bool invoke_basic_stack_ref_callback 1860 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method, 1861 int slot, oop obj); 1862 static inline bool invoke_basic_object_reference_callback 1863 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index); 1864 1865 // invoke advanced style callbacks 1866 static inline bool invoke_advanced_heap_root_callback 1867 (jvmtiHeapReferenceKind ref_kind, oop obj); 1868 static inline bool invoke_advanced_stack_ref_callback 1869 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth, 1870 jmethodID method, jlocation bci, jint slot, oop obj); 1871 static inline bool invoke_advanced_object_reference_callback 1872 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index); 1873 1874 // used to report the value of primitive fields 1875 static inline bool report_primitive_field 1876 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type); 1877 1878 public: 1879 // initialize for basic mode 1880 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, 1881 GrowableArray<oop>* visit_stack, 1882 const void* user_data, 1883 BasicHeapWalkContext context); 1884 1885 // initialize for advanced mode 1886 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, 1887 GrowableArray<oop>* visit_stack, 1888 const void* user_data, 1889 AdvancedHeapWalkContext context); 1890 1891 // functions to report roots 1892 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o); 1893 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth, 1894 jmethodID m, oop o); 1895 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth, 1896 jmethodID method, jlocation bci, jint slot, oop o); 1897 1898 // functions to report references 1899 static inline bool report_array_element_reference(oop referrer, oop referree, jint index); 1900 static inline bool report_class_reference(oop referrer, oop referree); 1901 static inline bool report_class_loader_reference(oop referrer, oop referree); 1902 static inline bool report_signers_reference(oop referrer, oop referree); 1903 static inline bool report_protection_domain_reference(oop referrer, oop referree); 1904 static inline bool report_superclass_reference(oop referrer, oop referree); 1905 static inline bool report_interface_reference(oop referrer, oop referree); 1906 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot); 1907 static inline bool report_field_reference(oop referrer, oop referree, jint slot); 1908 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index); 1909 static inline bool report_primitive_array_values(oop array); 1910 static inline bool report_string_value(oop str); 1911 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type); 1912 static inline bool report_primitive_static_field(oop o, jint index, address value, char type); 1913 }; 1914 1915 // statics 1916 int CallbackInvoker::_heap_walk_type; 1917 BasicHeapWalkContext CallbackInvoker::_basic_context; 1918 AdvancedHeapWalkContext CallbackInvoker::_advanced_context; 1919 JvmtiTagMap* CallbackInvoker::_tag_map; 1920 const void* CallbackInvoker::_user_data; 1921 GrowableArray<oop>* CallbackInvoker::_visit_stack; 1922 1923 // initialize for basic heap walk (IterateOverReachableObjects et al) 1924 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, 1925 GrowableArray<oop>* visit_stack, 1926 const void* user_data, 1927 BasicHeapWalkContext context) { 1928 _tag_map = tag_map; 1929 _visit_stack = visit_stack; 1930 _user_data = user_data; 1931 _basic_context = context; 1932 _advanced_context.invalidate(); // will trigger assertion if used 1933 _heap_walk_type = basic; 1934 } 1935 1936 // initialize for advanced heap walk (FollowReferences) 1937 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, 1938 GrowableArray<oop>* visit_stack, 1939 const void* user_data, 1940 AdvancedHeapWalkContext context) { 1941 _tag_map = tag_map; 1942 _visit_stack = visit_stack; 1943 _user_data = user_data; 1944 _advanced_context = context; 1945 _basic_context.invalidate(); // will trigger assertion if used 1946 _heap_walk_type = advanced; 1947 } 1948 1949 1950 // invoke basic style heap root callback 1951 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) { 1952 assert(ServiceUtil::visible_oop(obj), "checking"); 1953 1954 // if we heap roots should be reported 1955 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback(); 1956 if (cb == NULL) { 1957 return check_for_visit(obj); 1958 } 1959 1960 CallbackWrapper wrapper(tag_map(), obj); 1961 jvmtiIterationControl control = (*cb)(root_kind, 1962 wrapper.klass_tag(), 1963 wrapper.obj_size(), 1964 wrapper.obj_tag_p(), 1965 (void*)user_data()); 1966 // push root to visit stack when following references 1967 if (control == JVMTI_ITERATION_CONTINUE && 1968 basic_context()->object_ref_callback() != NULL) { 1969 visit_stack()->push(obj); 1970 } 1971 return control != JVMTI_ITERATION_ABORT; 1972 } 1973 1974 // invoke basic style stack ref callback 1975 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind, 1976 jlong thread_tag, 1977 jint depth, 1978 jmethodID method, 1979 jint slot, 1980 oop obj) { 1981 assert(ServiceUtil::visible_oop(obj), "checking"); 1982 1983 // if we stack refs should be reported 1984 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback(); 1985 if (cb == NULL) { 1986 return check_for_visit(obj); 1987 } 1988 1989 CallbackWrapper wrapper(tag_map(), obj); 1990 jvmtiIterationControl control = (*cb)(root_kind, 1991 wrapper.klass_tag(), 1992 wrapper.obj_size(), 1993 wrapper.obj_tag_p(), 1994 thread_tag, 1995 depth, 1996 method, 1997 slot, 1998 (void*)user_data()); 1999 // push root to visit stack when following references 2000 if (control == JVMTI_ITERATION_CONTINUE && 2001 basic_context()->object_ref_callback() != NULL) { 2002 visit_stack()->push(obj); 2003 } 2004 return control != JVMTI_ITERATION_ABORT; 2005 } 2006 2007 // invoke basic style object reference callback 2008 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind, 2009 oop referrer, 2010 oop referree, 2011 jint index) { 2012 2013 assert(ServiceUtil::visible_oop(referrer), "checking"); 2014 assert(ServiceUtil::visible_oop(referree), "checking"); 2015 2016 BasicHeapWalkContext* context = basic_context(); 2017 2018 // callback requires the referrer's tag. If it's the same referrer 2019 // as the last call then we use the cached value. 2020 jlong referrer_tag; 2021 if (referrer == context->last_referrer()) { 2022 referrer_tag = context->last_referrer_tag(); 2023 } else { 2024 referrer_tag = tag_for(tag_map(), referrer); 2025 } 2026 2027 // do the callback 2028 CallbackWrapper wrapper(tag_map(), referree); 2029 jvmtiObjectReferenceCallback cb = context->object_ref_callback(); 2030 jvmtiIterationControl control = (*cb)(ref_kind, 2031 wrapper.klass_tag(), 2032 wrapper.obj_size(), 2033 wrapper.obj_tag_p(), 2034 referrer_tag, 2035 index, 2036 (void*)user_data()); 2037 2038 // record referrer and referrer tag. For self-references record the 2039 // tag value from the callback as this might differ from referrer_tag. 2040 context->set_last_referrer(referrer); 2041 if (referrer == referree) { 2042 context->set_last_referrer_tag(*wrapper.obj_tag_p()); 2043 } else { 2044 context->set_last_referrer_tag(referrer_tag); 2045 } 2046 2047 if (control == JVMTI_ITERATION_CONTINUE) { 2048 return check_for_visit(referree); 2049 } else { 2050 return control != JVMTI_ITERATION_ABORT; 2051 } 2052 } 2053 2054 // invoke advanced style heap root callback 2055 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind, 2056 oop obj) { 2057 assert(ServiceUtil::visible_oop(obj), "checking"); 2058 2059 AdvancedHeapWalkContext* context = advanced_context(); 2060 2061 // check that callback is provided 2062 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 2063 if (cb == NULL) { 2064 return check_for_visit(obj); 2065 } 2066 2067 // apply class filter 2068 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2069 return check_for_visit(obj); 2070 } 2071 2072 // setup the callback wrapper 2073 CallbackWrapper wrapper(tag_map(), obj); 2074 2075 // apply tag filter 2076 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2077 wrapper.klass_tag(), 2078 context->heap_filter())) { 2079 return check_for_visit(obj); 2080 } 2081 2082 // for arrays we need the length, otherwise -1 2083 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 2084 2085 // invoke the callback 2086 jint res = (*cb)(ref_kind, 2087 NULL, // referrer info 2088 wrapper.klass_tag(), 2089 0, // referrer_class_tag is 0 for heap root 2090 wrapper.obj_size(), 2091 wrapper.obj_tag_p(), 2092 NULL, // referrer_tag_p 2093 len, 2094 (void*)user_data()); 2095 if (res & JVMTI_VISIT_ABORT) { 2096 return false;// referrer class tag 2097 } 2098 if (res & JVMTI_VISIT_OBJECTS) { 2099 check_for_visit(obj); 2100 } 2101 return true; 2102 } 2103 2104 // report a reference from a thread stack to an object 2105 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind, 2106 jlong thread_tag, 2107 jlong tid, 2108 int depth, 2109 jmethodID method, 2110 jlocation bci, 2111 jint slot, 2112 oop obj) { 2113 assert(ServiceUtil::visible_oop(obj), "checking"); 2114 2115 AdvancedHeapWalkContext* context = advanced_context(); 2116 2117 // check that callback is provider 2118 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 2119 if (cb == NULL) { 2120 return check_for_visit(obj); 2121 } 2122 2123 // apply class filter 2124 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2125 return check_for_visit(obj); 2126 } 2127 2128 // setup the callback wrapper 2129 CallbackWrapper wrapper(tag_map(), obj); 2130 2131 // apply tag filter 2132 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2133 wrapper.klass_tag(), 2134 context->heap_filter())) { 2135 return check_for_visit(obj); 2136 } 2137 2138 // setup the referrer info 2139 jvmtiHeapReferenceInfo reference_info; 2140 reference_info.stack_local.thread_tag = thread_tag; 2141 reference_info.stack_local.thread_id = tid; 2142 reference_info.stack_local.depth = depth; 2143 reference_info.stack_local.method = method; 2144 reference_info.stack_local.location = bci; 2145 reference_info.stack_local.slot = slot; 2146 2147 // for arrays we need the length, otherwise -1 2148 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 2149 2150 // call into the agent 2151 int res = (*cb)(ref_kind, 2152 &reference_info, 2153 wrapper.klass_tag(), 2154 0, // referrer_class_tag is 0 for heap root (stack) 2155 wrapper.obj_size(), 2156 wrapper.obj_tag_p(), 2157 NULL, // referrer_tag is 0 for root 2158 len, 2159 (void*)user_data()); 2160 2161 if (res & JVMTI_VISIT_ABORT) { 2162 return false; 2163 } 2164 if (res & JVMTI_VISIT_OBJECTS) { 2165 check_for_visit(obj); 2166 } 2167 return true; 2168 } 2169 2170 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback 2171 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed. 2172 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \ 2173 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \ 2174 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \ 2175 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \ 2176 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \ 2177 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL)) 2178 2179 // invoke the object reference callback to report a reference 2180 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind, 2181 oop referrer, 2182 oop obj, 2183 jint index) 2184 { 2185 // field index is only valid field in reference_info 2186 static jvmtiHeapReferenceInfo reference_info = { 0 }; 2187 2188 assert(ServiceUtil::visible_oop(referrer), "checking"); 2189 assert(ServiceUtil::visible_oop(obj), "checking"); 2190 2191 AdvancedHeapWalkContext* context = advanced_context(); 2192 2193 // check that callback is provider 2194 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 2195 if (cb == NULL) { 2196 return check_for_visit(obj); 2197 } 2198 2199 // apply class filter 2200 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2201 return check_for_visit(obj); 2202 } 2203 2204 // setup the callback wrapper 2205 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj); 2206 2207 // apply tag filter 2208 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2209 wrapper.klass_tag(), 2210 context->heap_filter())) { 2211 return check_for_visit(obj); 2212 } 2213 2214 // field index is only valid field in reference_info 2215 reference_info.field.index = index; 2216 2217 // for arrays we need the length, otherwise -1 2218 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 2219 2220 // invoke the callback 2221 int res = (*cb)(ref_kind, 2222 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL, 2223 wrapper.klass_tag(), 2224 wrapper.referrer_klass_tag(), 2225 wrapper.obj_size(), 2226 wrapper.obj_tag_p(), 2227 wrapper.referrer_tag_p(), 2228 len, 2229 (void*)user_data()); 2230 2231 if (res & JVMTI_VISIT_ABORT) { 2232 return false; 2233 } 2234 if (res & JVMTI_VISIT_OBJECTS) { 2235 check_for_visit(obj); 2236 } 2237 return true; 2238 } 2239 2240 // report a "simple root" 2241 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) { 2242 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL && 2243 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root"); 2244 assert(ServiceUtil::visible_oop(obj), "checking"); 2245 2246 if (is_basic_heap_walk()) { 2247 // map to old style root kind 2248 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind); 2249 return invoke_basic_heap_root_callback(root_kind, obj); 2250 } else { 2251 assert(is_advanced_heap_walk(), "wrong heap walk type"); 2252 return invoke_advanced_heap_root_callback(kind, obj); 2253 } 2254 } 2255 2256 2257 // invoke the primitive array values 2258 inline bool CallbackInvoker::report_primitive_array_values(oop obj) { 2259 assert(obj->is_typeArray(), "not a primitive array"); 2260 2261 AdvancedHeapWalkContext* context = advanced_context(); 2262 assert(context->array_primitive_value_callback() != NULL, "no callback"); 2263 2264 // apply class filter 2265 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2266 return true; 2267 } 2268 2269 CallbackWrapper wrapper(tag_map(), obj); 2270 2271 // apply tag filter 2272 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2273 wrapper.klass_tag(), 2274 context->heap_filter())) { 2275 return true; 2276 } 2277 2278 // invoke the callback 2279 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(), 2280 &wrapper, 2281 obj, 2282 (void*)user_data()); 2283 return (!(res & JVMTI_VISIT_ABORT)); 2284 } 2285 2286 // invoke the string value callback 2287 inline bool CallbackInvoker::report_string_value(oop str) { 2288 assert(str->klass() == SystemDictionary::String_klass(), "not a string"); 2289 2290 AdvancedHeapWalkContext* context = advanced_context(); 2291 assert(context->string_primitive_value_callback() != NULL, "no callback"); 2292 2293 // apply class filter 2294 if (is_filtered_by_klass_filter(str, context->klass_filter())) { 2295 return true; 2296 } 2297 2298 CallbackWrapper wrapper(tag_map(), str); 2299 2300 // apply tag filter 2301 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2302 wrapper.klass_tag(), 2303 context->heap_filter())) { 2304 return true; 2305 } 2306 2307 // invoke the callback 2308 int res = invoke_string_value_callback(context->string_primitive_value_callback(), 2309 &wrapper, 2310 str, 2311 (void*)user_data()); 2312 return (!(res & JVMTI_VISIT_ABORT)); 2313 } 2314 2315 // invoke the primitive field callback 2316 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind, 2317 oop obj, 2318 jint index, 2319 address addr, 2320 char type) 2321 { 2322 // for primitive fields only the index will be set 2323 static jvmtiHeapReferenceInfo reference_info = { 0 }; 2324 2325 AdvancedHeapWalkContext* context = advanced_context(); 2326 assert(context->primitive_field_callback() != NULL, "no callback"); 2327 2328 // apply class filter 2329 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 2330 return true; 2331 } 2332 2333 CallbackWrapper wrapper(tag_map(), obj); 2334 2335 // apply tag filter 2336 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 2337 wrapper.klass_tag(), 2338 context->heap_filter())) { 2339 return true; 2340 } 2341 2342 // the field index in the referrer 2343 reference_info.field.index = index; 2344 2345 // map the type 2346 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 2347 2348 // setup the jvalue 2349 jvalue value; 2350 copy_to_jvalue(&value, addr, value_type); 2351 2352 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback(); 2353 int res = (*cb)(ref_kind, 2354 &reference_info, 2355 wrapper.klass_tag(), 2356 wrapper.obj_tag_p(), 2357 value, 2358 value_type, 2359 (void*)user_data()); 2360 return (!(res & JVMTI_VISIT_ABORT)); 2361 } 2362 2363 2364 // instance field 2365 inline bool CallbackInvoker::report_primitive_instance_field(oop obj, 2366 jint index, 2367 address value, 2368 char type) { 2369 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD, 2370 obj, 2371 index, 2372 value, 2373 type); 2374 } 2375 2376 // static field 2377 inline bool CallbackInvoker::report_primitive_static_field(oop obj, 2378 jint index, 2379 address value, 2380 char type) { 2381 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD, 2382 obj, 2383 index, 2384 value, 2385 type); 2386 } 2387 2388 // report a JNI local (root object) to the profiler 2389 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) { 2390 if (is_basic_heap_walk()) { 2391 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL, 2392 thread_tag, 2393 depth, 2394 m, 2395 -1, 2396 obj); 2397 } else { 2398 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL, 2399 thread_tag, tid, 2400 depth, 2401 m, 2402 (jlocation)-1, 2403 -1, 2404 obj); 2405 } 2406 } 2407 2408 2409 // report a local (stack reference, root object) 2410 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag, 2411 jlong tid, 2412 jint depth, 2413 jmethodID method, 2414 jlocation bci, 2415 jint slot, 2416 oop obj) { 2417 if (is_basic_heap_walk()) { 2418 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL, 2419 thread_tag, 2420 depth, 2421 method, 2422 slot, 2423 obj); 2424 } else { 2425 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL, 2426 thread_tag, 2427 tid, 2428 depth, 2429 method, 2430 bci, 2431 slot, 2432 obj); 2433 } 2434 } 2435 2436 // report an object referencing a class. 2437 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) { 2438 if (is_basic_heap_walk()) { 2439 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); 2440 } else { 2441 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1); 2442 } 2443 } 2444 2445 // report a class referencing its class loader. 2446 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) { 2447 if (is_basic_heap_walk()) { 2448 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1); 2449 } else { 2450 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1); 2451 } 2452 } 2453 2454 // report a class referencing its signers. 2455 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) { 2456 if (is_basic_heap_walk()) { 2457 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1); 2458 } else { 2459 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1); 2460 } 2461 } 2462 2463 // report a class referencing its protection domain.. 2464 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) { 2465 if (is_basic_heap_walk()) { 2466 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); 2467 } else { 2468 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); 2469 } 2470 } 2471 2472 // report a class referencing its superclass. 2473 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) { 2474 if (is_basic_heap_walk()) { 2475 // Send this to be consistent with past implementation 2476 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); 2477 } else { 2478 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1); 2479 } 2480 } 2481 2482 // report a class referencing one of its interfaces. 2483 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) { 2484 if (is_basic_heap_walk()) { 2485 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1); 2486 } else { 2487 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1); 2488 } 2489 } 2490 2491 // report a class referencing one of its static fields. 2492 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) { 2493 if (is_basic_heap_walk()) { 2494 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot); 2495 } else { 2496 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot); 2497 } 2498 } 2499 2500 // report an array referencing an element object 2501 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) { 2502 if (is_basic_heap_walk()) { 2503 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); 2504 } else { 2505 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); 2506 } 2507 } 2508 2509 // report an object referencing an instance field object 2510 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) { 2511 if (is_basic_heap_walk()) { 2512 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot); 2513 } else { 2514 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot); 2515 } 2516 } 2517 2518 // report an array referencing an element object 2519 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) { 2520 if (is_basic_heap_walk()) { 2521 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index); 2522 } else { 2523 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index); 2524 } 2525 } 2526 2527 // A supporting closure used to process simple roots 2528 class SimpleRootsClosure : public OopClosure { 2529 private: 2530 jvmtiHeapReferenceKind _kind; 2531 bool _continue; 2532 2533 jvmtiHeapReferenceKind root_kind() { return _kind; } 2534 2535 public: 2536 void set_kind(jvmtiHeapReferenceKind kind) { 2537 _kind = kind; 2538 _continue = true; 2539 } 2540 2541 inline bool stopped() { 2542 return !_continue; 2543 } 2544 2545 void do_oop(oop* obj_p) { 2546 // iteration has terminated 2547 if (stopped()) { 2548 return; 2549 } 2550 2551 // ignore null or deleted handles 2552 oop o = *obj_p; 2553 if (o == NULL || o == JNIHandles::deleted_handle()) { 2554 return; 2555 } 2556 2557 assert(Universe::heap()->is_in_reserved(o), "should be impossible"); 2558 2559 jvmtiHeapReferenceKind kind = root_kind(); 2560 if (kind == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) { 2561 // SystemDictionary::always_strong_oops_do reports the application 2562 // class loader as a root. We want this root to be reported as 2563 // a root kind of "OTHER" rather than "SYSTEM_CLASS". 2564 if (!o->is_instanceMirror()) { 2565 kind = JVMTI_HEAP_REFERENCE_OTHER; 2566 } 2567 } 2568 2569 // some objects are ignored - in the case of simple 2570 // roots it's mostly Symbol*s that we are skipping 2571 // here. 2572 if (!ServiceUtil::visible_oop(o)) { 2573 return; 2574 } 2575 2576 // invoke the callback 2577 _continue = CallbackInvoker::report_simple_root(kind, o); 2578 2579 } 2580 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } 2581 }; 2582 2583 // A supporting closure used to process JNI locals 2584 class JNILocalRootsClosure : public OopClosure { 2585 private: 2586 jlong _thread_tag; 2587 jlong _tid; 2588 jint _depth; 2589 jmethodID _method; 2590 bool _continue; 2591 public: 2592 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) { 2593 _thread_tag = thread_tag; 2594 _tid = tid; 2595 _depth = depth; 2596 _method = method; 2597 _continue = true; 2598 } 2599 2600 inline bool stopped() { 2601 return !_continue; 2602 } 2603 2604 void do_oop(oop* obj_p) { 2605 // iteration has terminated 2606 if (stopped()) { 2607 return; 2608 } 2609 2610 // ignore null or deleted handles 2611 oop o = *obj_p; 2612 if (o == NULL || o == JNIHandles::deleted_handle()) { 2613 return; 2614 } 2615 2616 if (!ServiceUtil::visible_oop(o)) { 2617 return; 2618 } 2619 2620 // invoke the callback 2621 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o); 2622 } 2623 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } 2624 }; 2625 2626 2627 // A VM operation to iterate over objects that are reachable from 2628 // a set of roots or an initial object. 2629 // 2630 // For VM_HeapWalkOperation the set of roots used is :- 2631 // 2632 // - All JNI global references 2633 // - All inflated monitors 2634 // - All classes loaded by the boot class loader (or all classes 2635 // in the event that class unloading is disabled) 2636 // - All java threads 2637 // - For each java thread then all locals and JNI local references 2638 // on the thread's execution stack 2639 // - All visible/explainable objects from Universes::oops_do 2640 // 2641 class VM_HeapWalkOperation: public VM_Operation { 2642 private: 2643 enum { 2644 initial_visit_stack_size = 4000 2645 }; 2646 2647 bool _is_advanced_heap_walk; // indicates FollowReferences 2648 JvmtiTagMap* _tag_map; 2649 Handle _initial_object; 2650 GrowableArray<oop>* _visit_stack; // the visit stack 2651 2652 bool _collecting_heap_roots; // are we collecting roots 2653 bool _following_object_refs; // are we following object references 2654 2655 bool _reporting_primitive_fields; // optional reporting 2656 bool _reporting_primitive_array_values; 2657 bool _reporting_string_values; 2658 2659 GrowableArray<oop>* create_visit_stack() { 2660 return new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(initial_visit_stack_size, true); 2661 } 2662 2663 // accessors 2664 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; } 2665 JvmtiTagMap* tag_map() const { return _tag_map; } 2666 Handle initial_object() const { return _initial_object; } 2667 2668 bool is_following_references() const { return _following_object_refs; } 2669 2670 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; } 2671 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; } 2672 bool is_reporting_string_values() const { return _reporting_string_values; } 2673 2674 GrowableArray<oop>* visit_stack() const { return _visit_stack; } 2675 2676 // iterate over the various object types 2677 inline bool iterate_over_array(oop o); 2678 inline bool iterate_over_type_array(oop o); 2679 inline bool iterate_over_class(oop o); 2680 inline bool iterate_over_object(oop o); 2681 2682 // root collection 2683 inline bool collect_simple_roots(); 2684 inline bool collect_stack_roots(); 2685 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk); 2686 2687 // visit an object 2688 inline bool visit(oop o); 2689 2690 public: 2691 VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2692 Handle initial_object, 2693 BasicHeapWalkContext callbacks, 2694 const void* user_data); 2695 2696 VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2697 Handle initial_object, 2698 AdvancedHeapWalkContext callbacks, 2699 const void* user_data); 2700 2701 ~VM_HeapWalkOperation(); 2702 2703 VMOp_Type type() const { return VMOp_HeapWalkOperation; } 2704 void doit(); 2705 }; 2706 2707 2708 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2709 Handle initial_object, 2710 BasicHeapWalkContext callbacks, 2711 const void* user_data) { 2712 _is_advanced_heap_walk = false; 2713 _tag_map = tag_map; 2714 _initial_object = initial_object; 2715 _following_object_refs = (callbacks.object_ref_callback() != NULL); 2716 _reporting_primitive_fields = false; 2717 _reporting_primitive_array_values = false; 2718 _reporting_string_values = false; 2719 _visit_stack = create_visit_stack(); 2720 2721 2722 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks); 2723 } 2724 2725 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2726 Handle initial_object, 2727 AdvancedHeapWalkContext callbacks, 2728 const void* user_data) { 2729 _is_advanced_heap_walk = true; 2730 _tag_map = tag_map; 2731 _initial_object = initial_object; 2732 _following_object_refs = true; 2733 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);; 2734 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);; 2735 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);; 2736 _visit_stack = create_visit_stack(); 2737 2738 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks); 2739 } 2740 2741 VM_HeapWalkOperation::~VM_HeapWalkOperation() { 2742 if (_following_object_refs) { 2743 assert(_visit_stack != NULL, "checking"); 2744 delete _visit_stack; 2745 _visit_stack = NULL; 2746 } 2747 } 2748 2749 // an array references its class and has a reference to 2750 // each element in the array 2751 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) { 2752 objArrayOop array = objArrayOop(o); 2753 2754 // array reference to its class 2755 oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror(); 2756 if (!CallbackInvoker::report_class_reference(o, mirror)) { 2757 return false; 2758 } 2759 2760 // iterate over the array and report each reference to a 2761 // non-null element 2762 for (int index=0; index<array->length(); index++) { 2763 oop elem = array->obj_at(index); 2764 if (elem == NULL) { 2765 continue; 2766 } 2767 2768 // report the array reference o[index] = elem 2769 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) { 2770 return false; 2771 } 2772 } 2773 return true; 2774 } 2775 2776 // a type array references its class 2777 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) { 2778 Klass* k = o->klass(); 2779 oop mirror = k->java_mirror(); 2780 if (!CallbackInvoker::report_class_reference(o, mirror)) { 2781 return false; 2782 } 2783 2784 // report the array contents if required 2785 if (is_reporting_primitive_array_values()) { 2786 if (!CallbackInvoker::report_primitive_array_values(o)) { 2787 return false; 2788 } 2789 } 2790 return true; 2791 } 2792 2793 #ifdef ASSERT 2794 // verify that a static oop field is in range 2795 static inline bool verify_static_oop(InstanceKlass* ik, 2796 oop mirror, int offset) { 2797 address obj_p = (address)mirror + offset; 2798 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror); 2799 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize); 2800 assert(end >= start, "sanity check"); 2801 2802 if (obj_p >= start && obj_p < end) { 2803 return true; 2804 } else { 2805 return false; 2806 } 2807 } 2808 #endif // #ifdef ASSERT 2809 2810 // a class references its super class, interfaces, class loader, ... 2811 // and finally its static fields 2812 inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) { 2813 int i; 2814 Klass* klass = java_lang_Class::as_Klass(java_class); 2815 2816 if (klass->oop_is_instance()) { 2817 InstanceKlass* ik = InstanceKlass::cast(klass); 2818 2819 // ignore the class if it's has been initialized yet 2820 if (!ik->is_linked()) { 2821 return true; 2822 } 2823 2824 // get the java mirror 2825 oop mirror = klass->java_mirror(); 2826 2827 // super (only if something more interesting than java.lang.Object) 2828 Klass* java_super = ik->java_super(); 2829 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) { 2830 oop super = java_super->java_mirror(); 2831 if (!CallbackInvoker::report_superclass_reference(mirror, super)) { 2832 return false; 2833 } 2834 } 2835 2836 // class loader 2837 oop cl = ik->class_loader(); 2838 if (cl != NULL) { 2839 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) { 2840 return false; 2841 } 2842 } 2843 2844 // protection domain 2845 oop pd = ik->protection_domain(); 2846 if (pd != NULL) { 2847 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) { 2848 return false; 2849 } 2850 } 2851 2852 // signers 2853 oop signers = ik->signers(); 2854 if (signers != NULL) { 2855 if (!CallbackInvoker::report_signers_reference(mirror, signers)) { 2856 return false; 2857 } 2858 } 2859 2860 // references from the constant pool 2861 { 2862 ConstantPool* pool = ik->constants(); 2863 for (int i = 1; i < pool->length(); i++) { 2864 constantTag tag = pool->tag_at(i).value(); 2865 if (tag.is_string() || tag.is_klass()) { 2866 oop entry; 2867 if (tag.is_string()) { 2868 entry = pool->resolved_string_at(i); 2869 // If the entry is non-null it is resolved. 2870 if (entry == NULL) continue; 2871 } else { 2872 entry = pool->resolved_klass_at(i)->java_mirror(); 2873 } 2874 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) { 2875 return false; 2876 } 2877 } 2878 } 2879 } 2880 2881 // interfaces 2882 // (These will already have been reported as references from the constant pool 2883 // but are specified by IterateOverReachableObjects and must be reported). 2884 Array<Klass*>* interfaces = ik->local_interfaces(); 2885 for (i = 0; i < interfaces->length(); i++) { 2886 oop interf = ((Klass*)interfaces->at(i))->java_mirror(); 2887 if (interf == NULL) { 2888 continue; 2889 } 2890 if (!CallbackInvoker::report_interface_reference(mirror, interf)) { 2891 return false; 2892 } 2893 } 2894 2895 // iterate over the static fields 2896 2897 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass); 2898 for (i=0; i<field_map->field_count(); i++) { 2899 ClassFieldDescriptor* field = field_map->field_at(i); 2900 char type = field->field_type(); 2901 if (!is_primitive_field_type(type)) { 2902 oop fld_o = mirror->obj_field(field->field_offset()); 2903 assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check"); 2904 if (fld_o != NULL) { 2905 int slot = field->field_index(); 2906 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) { 2907 delete field_map; 2908 return false; 2909 } 2910 } 2911 } else { 2912 if (is_reporting_primitive_fields()) { 2913 address addr = (address)mirror + field->field_offset(); 2914 int slot = field->field_index(); 2915 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) { 2916 delete field_map; 2917 return false; 2918 } 2919 } 2920 } 2921 } 2922 delete field_map; 2923 2924 return true; 2925 } 2926 2927 return true; 2928 } 2929 2930 // an object references a class and its instance fields 2931 // (static fields are ignored here as we report these as 2932 // references from the class). 2933 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) { 2934 // reference to the class 2935 if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) { 2936 return false; 2937 } 2938 2939 // iterate over instance fields 2940 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o); 2941 for (int i=0; i<field_map->field_count(); i++) { 2942 ClassFieldDescriptor* field = field_map->field_at(i); 2943 char type = field->field_type(); 2944 if (!is_primitive_field_type(type)) { 2945 oop fld_o = o->obj_field(field->field_offset()); 2946 // ignore any objects that aren't visible to profiler 2947 if (fld_o != NULL && ServiceUtil::visible_oop(fld_o)) { 2948 assert(Universe::heap()->is_in_reserved(fld_o), "unsafe code should not " 2949 "have references to Klass* anymore"); 2950 int slot = field->field_index(); 2951 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) { 2952 return false; 2953 } 2954 } 2955 } else { 2956 if (is_reporting_primitive_fields()) { 2957 // primitive instance field 2958 address addr = (address)o + field->field_offset(); 2959 int slot = field->field_index(); 2960 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) { 2961 return false; 2962 } 2963 } 2964 } 2965 } 2966 2967 // if the object is a java.lang.String 2968 if (is_reporting_string_values() && 2969 o->klass() == SystemDictionary::String_klass()) { 2970 if (!CallbackInvoker::report_string_value(o)) { 2971 return false; 2972 } 2973 } 2974 return true; 2975 } 2976 2977 2978 // Collects all simple (non-stack) roots except for threads; 2979 // threads are handled in collect_stack_roots() as an optimization. 2980 // if there's a heap root callback provided then the callback is 2981 // invoked for each simple root. 2982 // if an object reference callback is provided then all simple 2983 // roots are pushed onto the marking stack so that they can be 2984 // processed later 2985 // 2986 inline bool VM_HeapWalkOperation::collect_simple_roots() { 2987 SimpleRootsClosure blk; 2988 2989 // JNI globals 2990 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL); 2991 JNIHandles::oops_do(&blk); 2992 if (blk.stopped()) { 2993 return false; 2994 } 2995 2996 // Preloaded classes and loader from the system dictionary 2997 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS); 2998 SystemDictionary::always_strong_oops_do(&blk); 2999 KlassToOopClosure klass_blk(&blk); 3000 ClassLoaderDataGraph::always_strong_oops_do(&blk, &klass_blk, false); 3001 if (blk.stopped()) { 3002 return false; 3003 } 3004 3005 // Inflated monitors 3006 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR); 3007 ObjectSynchronizer::oops_do(&blk); 3008 if (blk.stopped()) { 3009 return false; 3010 } 3011 3012 // threads are now handled in collect_stack_roots() 3013 3014 // Other kinds of roots maintained by HotSpot 3015 // Many of these won't be visible but others (such as instances of important 3016 // exceptions) will be visible. 3017 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER); 3018 Universe::oops_do(&blk); 3019 3020 // If there are any non-perm roots in the code cache, visit them. 3021 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER); 3022 CodeBlobToOopClosure look_in_blobs(&blk, false); 3023 CodeCache::scavenge_root_nmethods_do(&look_in_blobs); 3024 3025 return true; 3026 } 3027 3028 // Walk the stack of a given thread and find all references (locals 3029 // and JNI calls) and report these as stack references 3030 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread, 3031 JNILocalRootsClosure* blk) 3032 { 3033 oop threadObj = java_thread->threadObj(); 3034 assert(threadObj != NULL, "sanity check"); 3035 3036 // only need to get the thread's tag once per thread 3037 jlong thread_tag = tag_for(_tag_map, threadObj); 3038 3039 // also need the thread id 3040 jlong tid = java_lang_Thread::thread_id(threadObj); 3041 3042 3043 if (java_thread->has_last_Java_frame()) { 3044 3045 // vframes are resource allocated 3046 Thread* current_thread = Thread::current(); 3047 ResourceMark rm(current_thread); 3048 HandleMark hm(current_thread); 3049 3050 RegisterMap reg_map(java_thread); 3051 frame f = java_thread->last_frame(); 3052 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread); 3053 3054 bool is_top_frame = true; 3055 int depth = 0; 3056 frame* last_entry_frame = NULL; 3057 3058 while (vf != NULL) { 3059 if (vf->is_java_frame()) { 3060 3061 // java frame (interpreted, compiled, ...) 3062 javaVFrame *jvf = javaVFrame::cast(vf); 3063 3064 // the jmethodID 3065 jmethodID method = jvf->method()->jmethod_id(); 3066 3067 if (!(jvf->method()->is_native())) { 3068 jlocation bci = (jlocation)jvf->bci(); 3069 StackValueCollection* locals = jvf->locals(); 3070 for (int slot=0; slot<locals->size(); slot++) { 3071 if (locals->at(slot)->type() == T_OBJECT) { 3072 oop o = locals->obj_at(slot)(); 3073 if (o == NULL) { 3074 continue; 3075 } 3076 3077 // stack reference 3078 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method, 3079 bci, slot, o)) { 3080 return false; 3081 } 3082 } 3083 } 3084 3085 StackValueCollection* exprs = jvf->expressions(); 3086 for (int index=0; index < exprs->size(); index++) { 3087 if (exprs->at(index)->type() == T_OBJECT) { 3088 oop o = exprs->obj_at(index)(); 3089 if (o == NULL) { 3090 continue; 3091 } 3092 3093 // stack reference 3094 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method, 3095 bci, locals->size() + index, o)) { 3096 return false; 3097 } 3098 } 3099 } 3100 3101 } else { 3102 blk->set_context(thread_tag, tid, depth, method); 3103 if (is_top_frame) { 3104 // JNI locals for the top frame. 3105 java_thread->active_handles()->oops_do(blk); 3106 } else { 3107 if (last_entry_frame != NULL) { 3108 // JNI locals for the entry frame 3109 assert(last_entry_frame->is_entry_frame(), "checking"); 3110 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk); 3111 } 3112 } 3113 } 3114 last_entry_frame = NULL; 3115 depth++; 3116 } else { 3117 // externalVFrame - for an entry frame then we report the JNI locals 3118 // when we find the corresponding javaVFrame 3119 frame* fr = vf->frame_pointer(); 3120 assert(fr != NULL, "sanity check"); 3121 if (fr->is_entry_frame()) { 3122 last_entry_frame = fr; 3123 } 3124 } 3125 3126 vf = vf->sender(); 3127 is_top_frame = false; 3128 } 3129 } else { 3130 // no last java frame but there may be JNI locals 3131 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL); 3132 java_thread->active_handles()->oops_do(blk); 3133 } 3134 return true; 3135 } 3136 3137 3138 // Collects the simple roots for all threads and collects all 3139 // stack roots - for each thread it walks the execution 3140 // stack to find all references and local JNI refs. 3141 inline bool VM_HeapWalkOperation::collect_stack_roots() { 3142 JNILocalRootsClosure blk; 3143 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) { 3144 oop threadObj = thread->threadObj(); 3145 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) { 3146 // Collect the simple root for this thread before we 3147 // collect its stack roots 3148 if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, 3149 threadObj)) { 3150 return false; 3151 } 3152 if (!collect_stack_roots(thread, &blk)) { 3153 return false; 3154 } 3155 } 3156 } 3157 return true; 3158 } 3159 3160 // visit an object 3161 // first mark the object as visited 3162 // second get all the outbound references from this object (in other words, all 3163 // the objects referenced by this object). 3164 // 3165 bool VM_HeapWalkOperation::visit(oop o) { 3166 // mark object as visited 3167 assert(!ObjectMarker::visited(o), "can't visit same object more than once"); 3168 ObjectMarker::mark(o); 3169 3170 // instance 3171 if (o->is_instance()) { 3172 if (o->klass() == SystemDictionary::Class_klass()) { 3173 if (!java_lang_Class::is_primitive(o)) { 3174 // a java.lang.Class 3175 return iterate_over_class(o); 3176 } 3177 } else { 3178 return iterate_over_object(o); 3179 } 3180 } 3181 3182 // object array 3183 if (o->is_objArray()) { 3184 return iterate_over_array(o); 3185 } 3186 3187 // type array 3188 if (o->is_typeArray()) { 3189 return iterate_over_type_array(o); 3190 } 3191 3192 return true; 3193 } 3194 3195 void VM_HeapWalkOperation::doit() { 3196 ResourceMark rm; 3197 ObjectMarkerController marker; 3198 ClassFieldMapCacheMark cm; 3199 3200 assert(visit_stack()->is_empty(), "visit stack must be empty"); 3201 3202 // the heap walk starts with an initial object or the heap roots 3203 if (initial_object().is_null()) { 3204 // If either collect_stack_roots() or collect_simple_roots() 3205 // returns false at this point, then there are no mark bits 3206 // to reset. 3207 ObjectMarker::set_needs_reset(false); 3208 3209 // Calling collect_stack_roots() before collect_simple_roots() 3210 // can result in a big performance boost for an agent that is 3211 // focused on analyzing references in the thread stacks. 3212 if (!collect_stack_roots()) return; 3213 3214 if (!collect_simple_roots()) return; 3215 3216 // no early return so enable heap traversal to reset the mark bits 3217 ObjectMarker::set_needs_reset(true); 3218 } else { 3219 visit_stack()->push(initial_object()()); 3220 } 3221 3222 // object references required 3223 if (is_following_references()) { 3224 3225 // visit each object until all reachable objects have been 3226 // visited or the callback asked to terminate the iteration. 3227 while (!visit_stack()->is_empty()) { 3228 oop o = visit_stack()->pop(); 3229 if (!ObjectMarker::visited(o)) { 3230 if (!visit(o)) { 3231 break; 3232 } 3233 } 3234 } 3235 } 3236 } 3237 3238 // iterate over all objects that are reachable from a set of roots 3239 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback, 3240 jvmtiStackReferenceCallback stack_ref_callback, 3241 jvmtiObjectReferenceCallback object_ref_callback, 3242 const void* user_data) { 3243 MutexLocker ml(Heap_lock); 3244 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback); 3245 VM_HeapWalkOperation op(this, Handle(), context, user_data); 3246 VMThread::execute(&op); 3247 } 3248 3249 // iterate over all objects that are reachable from a given object 3250 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object, 3251 jvmtiObjectReferenceCallback object_ref_callback, 3252 const void* user_data) { 3253 oop obj = JNIHandles::resolve(object); 3254 Handle initial_object(Thread::current(), obj); 3255 3256 MutexLocker ml(Heap_lock); 3257 BasicHeapWalkContext context(NULL, NULL, object_ref_callback); 3258 VM_HeapWalkOperation op(this, initial_object, context, user_data); 3259 VMThread::execute(&op); 3260 } 3261 3262 // follow references from an initial object or the GC roots 3263 void JvmtiTagMap::follow_references(jint heap_filter, 3264 KlassHandle klass, 3265 jobject object, 3266 const jvmtiHeapCallbacks* callbacks, 3267 const void* user_data) 3268 { 3269 oop obj = JNIHandles::resolve(object); 3270 Handle initial_object(Thread::current(), obj); 3271 3272 MutexLocker ml(Heap_lock); 3273 AdvancedHeapWalkContext context(heap_filter, klass, callbacks); 3274 VM_HeapWalkOperation op(this, initial_object, context, user_data); 3275 VMThread::execute(&op); 3276 } 3277 3278 3279 void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) { 3280 // No locks during VM bring-up (0 threads) and no safepoints after main 3281 // thread creation and before VMThread creation (1 thread); initial GC 3282 // verification can happen in that window which gets to here. 3283 assert(Threads::number_of_threads() <= 1 || 3284 SafepointSynchronize::is_at_safepoint(), 3285 "must be executed at a safepoint"); 3286 if (JvmtiEnv::environments_might_exist()) { 3287 JvmtiEnvIterator it; 3288 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) { 3289 JvmtiTagMap* tag_map = env->tag_map(); 3290 if (tag_map != NULL && !tag_map->is_empty()) { 3291 tag_map->do_weak_oops(is_alive, f); 3292 } 3293 } 3294 } 3295 } 3296 3297 void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) { 3298 3299 // does this environment have the OBJECT_FREE event enabled 3300 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE); 3301 3302 // counters used for trace message 3303 int freed = 0; 3304 int moved = 0; 3305 3306 JvmtiTagHashmap* hashmap = this->hashmap(); 3307 3308 // reenable sizing (if disabled) 3309 hashmap->set_resizing_enabled(true); 3310 3311 // if the hashmap is empty then we can skip it 3312 if (hashmap->_entry_count == 0) { 3313 return; 3314 } 3315 3316 // now iterate through each entry in the table 3317 3318 JvmtiTagHashmapEntry** table = hashmap->table(); 3319 int size = hashmap->size(); 3320 3321 JvmtiTagHashmapEntry* delayed_add = NULL; 3322 3323 for (int pos = 0; pos < size; ++pos) { 3324 JvmtiTagHashmapEntry* entry = table[pos]; 3325 JvmtiTagHashmapEntry* prev = NULL; 3326 3327 while (entry != NULL) { 3328 JvmtiTagHashmapEntry* next = entry->next(); 3329 3330 oop* obj = entry->object_addr(); 3331 3332 // has object been GC'ed 3333 if (!is_alive->do_object_b(entry->object())) { 3334 // grab the tag 3335 jlong tag = entry->tag(); 3336 guarantee(tag != 0, "checking"); 3337 3338 // remove GC'ed entry from hashmap and return the 3339 // entry to the free list 3340 hashmap->remove(prev, pos, entry); 3341 destroy_entry(entry); 3342 3343 // post the event to the profiler 3344 if (post_object_free) { 3345 JvmtiExport::post_object_free(env(), tag); 3346 } 3347 3348 ++freed; 3349 } else { 3350 f->do_oop(entry->object_addr()); 3351 oop new_oop = entry->object(); 3352 3353 // if the object has moved then re-hash it and move its 3354 // entry to its new location. 3355 unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size); 3356 if (new_pos != (unsigned int)pos) { 3357 if (prev == NULL) { 3358 table[pos] = next; 3359 } else { 3360 prev->set_next(next); 3361 } 3362 if (new_pos < (unsigned int)pos) { 3363 entry->set_next(table[new_pos]); 3364 table[new_pos] = entry; 3365 } else { 3366 // Delay adding this entry to it's new position as we'd end up 3367 // hitting it again during this iteration. 3368 entry->set_next(delayed_add); 3369 delayed_add = entry; 3370 } 3371 moved++; 3372 } else { 3373 // object didn't move 3374 prev = entry; 3375 } 3376 } 3377 3378 entry = next; 3379 } 3380 } 3381 3382 // Re-add all the entries which were kept aside 3383 while (delayed_add != NULL) { 3384 JvmtiTagHashmapEntry* next = delayed_add->next(); 3385 unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size); 3386 delayed_add->set_next(table[pos]); 3387 table[pos] = delayed_add; 3388 delayed_add = next; 3389 } 3390 3391 // stats 3392 if (TraceJVMTIObjectTagging) { 3393 int post_total = hashmap->_entry_count; 3394 int pre_total = post_total + freed; 3395 3396 tty->print_cr("(%d->%d, %d freed, %d total moves)", 3397 pre_total, post_total, freed, moved); 3398 } 3399 }