1 /*
   2  * Copyright (c) 2003, 2017, 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/javaClasses.inline.hpp"
  27 #include "classfile/symbolTable.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "jvmtifiles/jvmtiEnv.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "oops/instanceMirrorKlass.hpp"
  34 #include "oops/objArrayKlass.hpp"
  35 #include "oops/objArrayOop.inline.hpp"
  36 #include "oops/oop.inline.hpp"
  37 #include "prims/jvmtiEventController.hpp"
  38 #include "prims/jvmtiEventController.inline.hpp"
  39 #include "prims/jvmtiExport.hpp"
  40 #include "prims/jvmtiImpl.hpp"
  41 #include "prims/jvmtiTagMap.hpp"
  42 #include "runtime/biasedLocking.hpp"
  43 #include "runtime/javaCalls.hpp"
  44 #include "runtime/jniHandles.hpp"
  45 #include "runtime/mutex.hpp"
  46 #include "runtime/mutexLocker.hpp"
  47 #include "runtime/reflectionUtils.hpp"
  48 #include "runtime/thread.inline.hpp"
  49 #include "runtime/threadSMR.hpp"
  50 #include "runtime/vframe.hpp"
  51 #include "runtime/vmThread.hpp"
  52 #include "runtime/vm_operations.hpp"
  53 #include "services/serviceUtil.hpp"
  54 #include "utilities/macros.hpp"
  55 #if INCLUDE_ALL_GCS
  56 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  57 #include "gc/parallel/parallelScavengeHeap.hpp"
  58 #endif // INCLUDE_ALL_GCS
  59 
  60 // JvmtiTagHashmapEntry
  61 //
  62 // Each entry encapsulates a reference to the tagged object
  63 // and the tag value. In addition an entry includes a next pointer which
  64 // is used to chain entries together.
  65 
  66 class JvmtiTagHashmapEntry : public CHeapObj<mtInternal> {
  67  private:
  68   friend class JvmtiTagMap;
  69 
  70   oop _object;                          // tagged object
  71   jlong _tag;                           // the tag
  72   JvmtiTagHashmapEntry* _next;          // next on the list
  73 
  74   inline void init(oop object, jlong tag) {
  75     _object = object;
  76     _tag = tag;
  77     _next = NULL;
  78   }
  79 
  80   // constructor
  81   JvmtiTagHashmapEntry(oop object, jlong tag)         { init(object, tag); }
  82 
  83  public:
  84 
  85   // accessor methods
  86   inline oop object() const                           { return _object; }
  87   inline oop* object_addr()                           { return &_object; }
  88   inline jlong tag() const                            { return _tag; }
  89 
  90   inline void set_tag(jlong tag) {
  91     assert(tag != 0, "can't be zero");
  92     _tag = tag;
  93   }
  94 
  95   inline JvmtiTagHashmapEntry* next() const             { return _next; }
  96   inline void set_next(JvmtiTagHashmapEntry* next)      { _next = next; }
  97 };
  98 
  99 
 100 // JvmtiTagHashmap
 101 //
 102 // A hashmap is essentially a table of pointers to entries. Entries
 103 // are hashed to a location, or position in the table, and then
 104 // chained from that location. The "key" for hashing is address of
 105 // the object, or oop. The "value" is the tag value.
 106 //
 107 // A hashmap maintains a count of the number entries in the hashmap
 108 // and resizes if the number of entries exceeds a given threshold.
 109 // The threshold is specified as a percentage of the size - for
 110 // example a threshold of 0.75 will trigger the hashmap to resize
 111 // if the number of entries is >75% of table size.
 112 //
 113 // A hashmap provides functions for adding, removing, and finding
 114 // entries. It also provides a function to iterate over all entries
 115 // in the hashmap.
 116 
 117 class JvmtiTagHashmap : public CHeapObj<mtInternal> {
 118  private:
 119   friend class JvmtiTagMap;
 120 
 121   enum {
 122     small_trace_threshold  = 10000,                  // threshold for tracing
 123     medium_trace_threshold = 100000,
 124     large_trace_threshold  = 1000000,
 125     initial_trace_threshold = small_trace_threshold
 126   };
 127 
 128   static int _sizes[];                  // array of possible hashmap sizes
 129   int _size;                            // actual size of the table
 130   int _size_index;                      // index into size table
 131 
 132   int _entry_count;                     // number of entries in the hashmap
 133 
 134   float _load_factor;                   // load factor as a % of the size
 135   int _resize_threshold;                // computed threshold to trigger resizing.
 136   bool _resizing_enabled;               // indicates if hashmap can resize
 137 
 138   int _trace_threshold;                 // threshold for trace messages
 139 
 140   JvmtiTagHashmapEntry** _table;        // the table of entries.
 141 
 142   // private accessors
 143   int resize_threshold() const                  { return _resize_threshold; }
 144   int trace_threshold() const                   { return _trace_threshold; }
 145 
 146   // initialize the hashmap
 147   void init(int size_index=0, float load_factor=4.0f) {
 148     int initial_size =  _sizes[size_index];
 149     _size_index = size_index;
 150     _size = initial_size;
 151     _entry_count = 0;
 152     _trace_threshold = initial_trace_threshold;
 153     _load_factor = load_factor;
 154     _resize_threshold = (int)(_load_factor * _size);
 155     _resizing_enabled = true;
 156     size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
 157     _table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
 158     if (_table == NULL) {
 159       vm_exit_out_of_memory(s, OOM_MALLOC_ERROR,
 160         "unable to allocate initial hashtable for jvmti object tags");
 161     }
 162     for (int i=0; i<initial_size; i++) {
 163       _table[i] = NULL;
 164     }
 165   }
 166 
 167   // hash a given key (oop) with the specified size
 168   static unsigned int hash(oop key, int size) {
 169     // shift right to get better distribution (as these bits will be zero
 170     // with aligned addresses)
 171     unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key));
 172 #ifdef _LP64
 173     return (addr >> 3) % size;
 174 #else
 175     return (addr >> 2) % size;
 176 #endif
 177   }
 178 
 179   // hash a given key (oop)
 180   unsigned int hash(oop key) {
 181     return hash(key, _size);
 182   }
 183 
 184   // resize the hashmap - allocates a large table and re-hashes
 185   // all entries into the new table.
 186   void resize() {
 187     int new_size_index = _size_index+1;
 188     int new_size = _sizes[new_size_index];
 189     if (new_size < 0) {
 190       // hashmap already at maximum capacity
 191       return;
 192     }
 193 
 194     // allocate new table
 195     size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
 196     JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
 197     if (new_table == NULL) {
 198       warning("unable to allocate larger hashtable for jvmti object tags");
 199       set_resizing_enabled(false);
 200       return;
 201     }
 202 
 203     // initialize new table
 204     int i;
 205     for (i=0; i<new_size; i++) {
 206       new_table[i] = NULL;
 207     }
 208 
 209     // rehash all entries into the new table
 210     for (i=0; i<_size; i++) {
 211       JvmtiTagHashmapEntry* entry = _table[i];
 212       while (entry != NULL) {
 213         JvmtiTagHashmapEntry* next = entry->next();
 214         oop key = entry->object();
 215         assert(key != NULL, "jni weak reference cleared!!");
 216         unsigned int h = hash(key, new_size);
 217         JvmtiTagHashmapEntry* anchor = new_table[h];
 218         if (anchor == NULL) {
 219           new_table[h] = entry;
 220           entry->set_next(NULL);
 221         } else {
 222           entry->set_next(anchor);
 223           new_table[h] = entry;
 224         }
 225         entry = next;
 226       }
 227     }
 228 
 229     // free old table and update settings.
 230     os::free((void*)_table);
 231     _table = new_table;
 232     _size_index = new_size_index;
 233     _size = new_size;
 234 
 235     // compute new resize threshold
 236     _resize_threshold = (int)(_load_factor * _size);
 237   }
 238 
 239 
 240   // internal remove function - remove an entry at a given position in the
 241   // table.
 242   inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
 243     assert(pos >= 0 && pos < _size, "out of range");
 244     if (prev == NULL) {
 245       _table[pos] = entry->next();
 246     } else {
 247       prev->set_next(entry->next());
 248     }
 249     assert(_entry_count > 0, "checking");
 250     _entry_count--;
 251   }
 252 
 253   // resizing switch
 254   bool is_resizing_enabled() const          { return _resizing_enabled; }
 255   void set_resizing_enabled(bool enable)    { _resizing_enabled = enable; }
 256 
 257   // debugging
 258   void print_memory_usage();
 259   void compute_next_trace_threshold();
 260 
 261  public:
 262 
 263   // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
 264   // The preferred size is rounded down to an actual size.
 265   JvmtiTagHashmap(int size, float load_factor=0.0f) {
 266     int i=0;
 267     while (_sizes[i] < size) {
 268       if (_sizes[i] < 0) {
 269         assert(i > 0, "sanity check");
 270         i--;
 271         break;
 272       }
 273       i++;
 274     }
 275 
 276     // if a load factor is specified then use it, otherwise use default
 277     if (load_factor > 0.01f) {
 278       init(i, load_factor);
 279     } else {
 280       init(i);
 281     }
 282   }
 283 
 284   // create a JvmtiTagHashmap with default settings
 285   JvmtiTagHashmap() {
 286     init();
 287   }
 288 
 289   // release table when JvmtiTagHashmap destroyed
 290   ~JvmtiTagHashmap() {
 291     if (_table != NULL) {
 292       os::free((void*)_table);
 293       _table = NULL;
 294     }
 295   }
 296 
 297   // accessors
 298   int size() const                              { return _size; }
 299   JvmtiTagHashmapEntry** table() const          { return _table; }
 300   int entry_count() const                       { return _entry_count; }
 301 
 302   // find an entry in the hashmap, returns NULL if not found.
 303   inline JvmtiTagHashmapEntry* find(oop key) {
 304     unsigned int h = hash(key);
 305     JvmtiTagHashmapEntry* entry = _table[h];
 306     while (entry != NULL) {
 307       if (entry->object() == key) {
 308          return entry;
 309       }
 310       entry = entry->next();
 311     }
 312     return NULL;
 313   }
 314 
 315 
 316   // add a new entry to hashmap
 317   inline void add(oop key, JvmtiTagHashmapEntry* entry) {
 318     assert(key != NULL, "checking");
 319     assert(find(key) == NULL, "duplicate detected");
 320     unsigned int h = hash(key);
 321     JvmtiTagHashmapEntry* anchor = _table[h];
 322     if (anchor == NULL) {
 323       _table[h] = entry;
 324       entry->set_next(NULL);
 325     } else {
 326       entry->set_next(anchor);
 327       _table[h] = entry;
 328     }
 329 
 330     _entry_count++;
 331     if (log_is_enabled(Debug, jvmti, objecttagging) && entry_count() >= trace_threshold()) {
 332       print_memory_usage();
 333       compute_next_trace_threshold();
 334     }
 335 
 336     // if the number of entries exceed the threshold then resize
 337     if (entry_count() > resize_threshold() && is_resizing_enabled()) {
 338       resize();
 339     }
 340   }
 341 
 342   // remove an entry with the given key.
 343   inline JvmtiTagHashmapEntry* remove(oop key) {
 344     unsigned int h = hash(key);
 345     JvmtiTagHashmapEntry* entry = _table[h];
 346     JvmtiTagHashmapEntry* prev = NULL;
 347     while (entry != NULL) {
 348       if (key == entry->object()) {
 349         break;
 350       }
 351       prev = entry;
 352       entry = entry->next();
 353     }
 354     if (entry != NULL) {
 355       remove(prev, h, entry);
 356     }
 357     return entry;
 358   }
 359 
 360   // iterate over all entries in the hashmap
 361   void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
 362 };
 363 
 364 // possible hashmap sizes - odd primes that roughly double in size.
 365 // To avoid excessive resizing the odd primes from 4801-76831 and
 366 // 76831-307261 have been removed. The list must be terminated by -1.
 367 int JvmtiTagHashmap::_sizes[] =  { 4801, 76831, 307261, 614563, 1228891,
 368     2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
 369 
 370 
 371 // A supporting class for iterating over all entries in Hashmap
 372 class JvmtiTagHashmapEntryClosure {
 373  public:
 374   virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
 375 };
 376 
 377 
 378 // iterate over all entries in the hashmap
 379 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
 380   for (int i=0; i<_size; i++) {
 381     JvmtiTagHashmapEntry* entry = _table[i];
 382     JvmtiTagHashmapEntry* prev = NULL;
 383     while (entry != NULL) {
 384       // obtain the next entry before invoking do_entry - this is
 385       // necessary because do_entry may remove the entry from the
 386       // hashmap.
 387       JvmtiTagHashmapEntry* next = entry->next();
 388       closure->do_entry(entry);
 389       entry = next;
 390      }
 391   }
 392 }
 393 
 394 // debugging
 395 void JvmtiTagHashmap::print_memory_usage() {
 396   intptr_t p = (intptr_t)this;
 397   tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
 398 
 399   // table + entries in KB
 400   int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
 401     entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
 402 
 403   int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
 404   tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
 405     entry_count(), hashmap_usage, weak_globals_usage);
 406 }
 407 
 408 // compute threshold for the next trace message
 409 void JvmtiTagHashmap::compute_next_trace_threshold() {
 410   _trace_threshold = entry_count();
 411   if (trace_threshold() < medium_trace_threshold) {
 412     _trace_threshold += small_trace_threshold;
 413   } else {
 414     if (trace_threshold() < large_trace_threshold) {
 415       _trace_threshold += medium_trace_threshold;
 416     } else {
 417       _trace_threshold += large_trace_threshold;
 418     }
 419   }
 420 }
 421 
 422 // create a JvmtiTagMap
 423 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
 424   _env(env),
 425   _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
 426   _free_entries(NULL),
 427   _free_entries_count(0)
 428 {
 429   assert(JvmtiThreadState_lock->is_locked(), "sanity check");
 430   assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
 431 
 432   _hashmap = new JvmtiTagHashmap();
 433 
 434   // finally add us to the environment
 435   ((JvmtiEnvBase *)env)->set_tag_map(this);
 436 }
 437 
 438 
 439 // destroy a JvmtiTagMap
 440 JvmtiTagMap::~JvmtiTagMap() {
 441 
 442   // no lock acquired as we assume the enclosing environment is
 443   // also being destroryed.
 444   ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
 445 
 446   JvmtiTagHashmapEntry** table = _hashmap->table();
 447   for (int j = 0; j < _hashmap->size(); j++) {
 448     JvmtiTagHashmapEntry* entry = table[j];
 449     while (entry != NULL) {
 450       JvmtiTagHashmapEntry* next = entry->next();
 451       delete entry;
 452       entry = next;
 453     }
 454   }
 455 
 456   // finally destroy the hashmap
 457   delete _hashmap;
 458   _hashmap = NULL;
 459 
 460   // remove any entries on the free list
 461   JvmtiTagHashmapEntry* entry = _free_entries;
 462   while (entry != NULL) {
 463     JvmtiTagHashmapEntry* next = entry->next();
 464     delete entry;
 465     entry = next;
 466   }
 467   _free_entries = NULL;
 468 }
 469 
 470 // create a hashmap entry
 471 // - if there's an entry on the (per-environment) free list then this
 472 // is returned. Otherwise an new entry is allocated.
 473 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
 474   assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
 475   JvmtiTagHashmapEntry* entry;
 476   if (_free_entries == NULL) {
 477     entry = new JvmtiTagHashmapEntry(ref, tag);
 478   } else {
 479     assert(_free_entries_count > 0, "mismatched _free_entries_count");
 480     _free_entries_count--;
 481     entry = _free_entries;
 482     _free_entries = entry->next();
 483     entry->init(ref, tag);
 484   }
 485   return entry;
 486 }
 487 
 488 // destroy an entry by returning it to the free list
 489 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
 490   assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
 491   // limit the size of the free list
 492   if (_free_entries_count >= max_free_entries) {
 493     delete entry;
 494   } else {
 495     entry->set_next(_free_entries);
 496     _free_entries = entry;
 497     _free_entries_count++;
 498   }
 499 }
 500 
 501 // returns the tag map for the given environments. If the tag map
 502 // doesn't exist then it is created.
 503 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
 504   JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
 505   if (tag_map == NULL) {
 506     MutexLocker mu(JvmtiThreadState_lock);
 507     tag_map = ((JvmtiEnvBase*)env)->tag_map();
 508     if (tag_map == NULL) {
 509       tag_map = new JvmtiTagMap(env);
 510     }
 511   } else {
 512     CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
 513   }
 514   return tag_map;
 515 }
 516 
 517 // iterate over all entries in the tag map.
 518 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
 519   hashmap()->entry_iterate(closure);
 520 }
 521 
 522 // returns true if the hashmaps are empty
 523 bool JvmtiTagMap::is_empty() {
 524   assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
 525   return hashmap()->entry_count() == 0;
 526 }
 527 
 528 
 529 // Return the tag value for an object, or 0 if the object is
 530 // not tagged
 531 //
 532 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
 533   JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
 534   if (entry == NULL) {
 535     return 0;
 536   } else {
 537     return entry->tag();
 538   }
 539 }
 540 
 541 
 542 // A CallbackWrapper is a support class for querying and tagging an object
 543 // around a callback to a profiler. The constructor does pre-callback
 544 // work to get the tag value, klass tag value, ... and the destructor
 545 // does the post-callback work of tagging or untagging the object.
 546 //
 547 // {
 548 //   CallbackWrapper wrapper(tag_map, o);
 549 //
 550 //   (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
 551 //
 552 // } // wrapper goes out of scope here which results in the destructor
 553 //      checking to see if the object has been tagged, untagged, or the
 554 //      tag value has changed.
 555 //
 556 class CallbackWrapper : public StackObj {
 557  private:
 558   JvmtiTagMap* _tag_map;
 559   JvmtiTagHashmap* _hashmap;
 560   JvmtiTagHashmapEntry* _entry;
 561   oop _o;
 562   jlong _obj_size;
 563   jlong _obj_tag;
 564   jlong _klass_tag;
 565 
 566  protected:
 567   JvmtiTagMap* tag_map() const      { return _tag_map; }
 568 
 569   // invoked post-callback to tag, untag, or update the tag of an object
 570   void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
 571                                        JvmtiTagHashmapEntry* entry, jlong obj_tag);
 572  public:
 573   CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
 574     assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
 575            "MT unsafe or must be VM thread");
 576 
 577     // object to tag
 578     _o = o;
 579 
 580     // object size
 581     _obj_size = (jlong)_o->size() * wordSize;
 582 
 583     // record the context
 584     _tag_map = tag_map;
 585     _hashmap = tag_map->hashmap();
 586     _entry = _hashmap->find(_o);
 587 
 588     // get object tag
 589     _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
 590 
 591     // get the class and the class's tag value
 592     assert(SystemDictionary::Class_klass()->is_mirror_instance_klass(), "Is not?");
 593 
 594     _klass_tag = tag_for(tag_map, _o->klass()->java_mirror());
 595   }
 596 
 597   ~CallbackWrapper() {
 598     post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
 599   }
 600 
 601   inline jlong* obj_tag_p()                     { return &_obj_tag; }
 602   inline jlong obj_size() const                 { return _obj_size; }
 603   inline jlong obj_tag() const                  { return _obj_tag; }
 604   inline jlong klass_tag() const                { return _klass_tag; }
 605 };
 606 
 607 
 608 
 609 // callback post-callback to tag, untag, or update the tag of an object
 610 void inline CallbackWrapper::post_callback_tag_update(oop o,
 611                                                       JvmtiTagHashmap* hashmap,
 612                                                       JvmtiTagHashmapEntry* entry,
 613                                                       jlong obj_tag) {
 614   if (entry == NULL) {
 615     if (obj_tag != 0) {
 616       // callback has tagged the object
 617       assert(Thread::current()->is_VM_thread(), "must be VMThread");
 618       entry = tag_map()->create_entry(o, obj_tag);
 619       hashmap->add(o, entry);
 620     }
 621   } else {
 622     // object was previously tagged - the callback may have untagged
 623     // the object or changed the tag value
 624     if (obj_tag == 0) {
 625 
 626       JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
 627       assert(entry_removed == entry, "checking");
 628       tag_map()->destroy_entry(entry);
 629 
 630     } else {
 631       if (obj_tag != entry->tag()) {
 632          entry->set_tag(obj_tag);
 633       }
 634     }
 635   }
 636 }
 637 
 638 // An extended CallbackWrapper used when reporting an object reference
 639 // to the agent.
 640 //
 641 // {
 642 //   TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
 643 //
 644 //   (*callback)(wrapper.klass_tag(),
 645 //               wrapper.obj_size(),
 646 //               wrapper.obj_tag_p()
 647 //               wrapper.referrer_tag_p(), ...)
 648 //
 649 // } // wrapper goes out of scope here which results in the destructor
 650 //      checking to see if the referrer object has been tagged, untagged,
 651 //      or the tag value has changed.
 652 //
 653 class TwoOopCallbackWrapper : public CallbackWrapper {
 654  private:
 655   bool _is_reference_to_self;
 656   JvmtiTagHashmap* _referrer_hashmap;
 657   JvmtiTagHashmapEntry* _referrer_entry;
 658   oop _referrer;
 659   jlong _referrer_obj_tag;
 660   jlong _referrer_klass_tag;
 661   jlong* _referrer_tag_p;
 662 
 663   bool is_reference_to_self() const             { return _is_reference_to_self; }
 664 
 665  public:
 666   TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
 667     CallbackWrapper(tag_map, o)
 668   {
 669     // self reference needs to be handled in a special way
 670     _is_reference_to_self = (referrer == o);
 671 
 672     if (_is_reference_to_self) {
 673       _referrer_klass_tag = klass_tag();
 674       _referrer_tag_p = obj_tag_p();
 675     } else {
 676       _referrer = referrer;
 677       // record the context
 678       _referrer_hashmap = tag_map->hashmap();
 679       _referrer_entry = _referrer_hashmap->find(_referrer);
 680 
 681       // get object tag
 682       _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
 683       _referrer_tag_p = &_referrer_obj_tag;
 684 
 685       // get referrer class tag.
 686       _referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror());
 687     }
 688   }
 689 
 690   ~TwoOopCallbackWrapper() {
 691     if (!is_reference_to_self()){
 692       post_callback_tag_update(_referrer,
 693                                _referrer_hashmap,
 694                                _referrer_entry,
 695                                _referrer_obj_tag);
 696     }
 697   }
 698 
 699   // address of referrer tag
 700   // (for a self reference this will return the same thing as obj_tag_p())
 701   inline jlong* referrer_tag_p()        { return _referrer_tag_p; }
 702 
 703   // referrer's class tag
 704   inline jlong referrer_klass_tag()     { return _referrer_klass_tag; }
 705 };
 706 
 707 // tag an object
 708 //
 709 // This function is performance critical. If many threads attempt to tag objects
 710 // around the same time then it's possible that the Mutex associated with the
 711 // tag map will be a hot lock.
 712 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
 713   MutexLocker ml(lock());
 714 
 715   // resolve the object
 716   oop o = JNIHandles::resolve_non_null(object);
 717 
 718   // see if the object is already tagged
 719   JvmtiTagHashmap* hashmap = _hashmap;
 720   JvmtiTagHashmapEntry* entry = hashmap->find(o);
 721 
 722   // if the object is not already tagged then we tag it
 723   if (entry == NULL) {
 724     if (tag != 0) {
 725       entry = create_entry(o, tag);
 726       hashmap->add(o, entry);
 727     } else {
 728       // no-op
 729     }
 730   } else {
 731     // if the object is already tagged then we either update
 732     // the tag (if a new tag value has been provided)
 733     // or remove the object if the new tag value is 0.
 734     if (tag == 0) {
 735       hashmap->remove(o);
 736       destroy_entry(entry);
 737     } else {
 738       entry->set_tag(tag);
 739     }
 740   }
 741 }
 742 
 743 // get the tag for an object
 744 jlong JvmtiTagMap::get_tag(jobject object) {
 745   MutexLocker ml(lock());
 746 
 747   // resolve the object
 748   oop o = JNIHandles::resolve_non_null(object);
 749 
 750   return tag_for(this, o);
 751 }
 752 
 753 
 754 // Helper class used to describe the static or instance fields of a class.
 755 // For each field it holds the field index (as defined by the JVMTI specification),
 756 // the field type, and the offset.
 757 
 758 class ClassFieldDescriptor: public CHeapObj<mtInternal> {
 759  private:
 760   int _field_index;
 761   int _field_offset;
 762   char _field_type;
 763  public:
 764   ClassFieldDescriptor(int index, char type, int offset) :
 765     _field_index(index), _field_type(type), _field_offset(offset) {
 766   }
 767   int field_index()  const  { return _field_index; }
 768   char field_type()  const  { return _field_type; }
 769   int field_offset() const  { return _field_offset; }
 770 };
 771 
 772 class ClassFieldMap: public CHeapObj<mtInternal> {
 773  private:
 774   enum {
 775     initial_field_count = 5
 776   };
 777 
 778   // list of field descriptors
 779   GrowableArray<ClassFieldDescriptor*>* _fields;
 780 
 781   // constructor
 782   ClassFieldMap();
 783 
 784   // add a field
 785   void add(int index, char type, int offset);
 786 
 787   // returns the field count for the given class
 788   static int compute_field_count(InstanceKlass* ik);
 789 
 790  public:
 791   ~ClassFieldMap();
 792 
 793   // access
 794   int field_count()                     { return _fields->length(); }
 795   ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
 796 
 797   // functions to create maps of static or instance fields
 798   static ClassFieldMap* create_map_of_static_fields(Klass* k);
 799   static ClassFieldMap* create_map_of_instance_fields(oop obj);
 800 };
 801 
 802 ClassFieldMap::ClassFieldMap() {
 803   _fields = new (ResourceObj::C_HEAP, mtInternal)
 804     GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
 805 }
 806 
 807 ClassFieldMap::~ClassFieldMap() {
 808   for (int i=0; i<_fields->length(); i++) {
 809     delete _fields->at(i);
 810   }
 811   delete _fields;
 812 }
 813 
 814 void ClassFieldMap::add(int index, char type, int offset) {
 815   ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
 816   _fields->append(field);
 817 }
 818 
 819 // Returns a heap allocated ClassFieldMap to describe the static fields
 820 // of the given class.
 821 //
 822 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
 823   HandleMark hm;
 824   InstanceKlass* ik = InstanceKlass::cast(k);
 825 
 826   // create the field map
 827   ClassFieldMap* field_map = new ClassFieldMap();
 828 
 829   FilteredFieldStream f(ik, false, false);
 830   int max_field_index = f.field_count()-1;
 831 
 832   int index = 0;
 833   for (FilteredFieldStream fld(ik, true, true); !fld.eos(); fld.next(), index++) {
 834     // ignore instance fields
 835     if (!fld.access_flags().is_static()) {
 836       continue;
 837     }
 838     field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
 839   }
 840   return field_map;
 841 }
 842 
 843 // Returns a heap allocated ClassFieldMap to describe the instance fields
 844 // of the given class. All instance fields are included (this means public
 845 // and private fields declared in superclasses and superinterfaces too).
 846 //
 847 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
 848   HandleMark hm;
 849   InstanceKlass* ik = InstanceKlass::cast(obj->klass());
 850 
 851   // create the field map
 852   ClassFieldMap* field_map = new ClassFieldMap();
 853 
 854   FilteredFieldStream f(ik, false, false);
 855 
 856   int max_field_index = f.field_count()-1;
 857 
 858   int index = 0;
 859   for (FilteredFieldStream fld(ik, false, false); !fld.eos(); fld.next(), index++) {
 860     // ignore static fields
 861     if (fld.access_flags().is_static()) {
 862       continue;
 863     }
 864     field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
 865   }
 866 
 867   return field_map;
 868 }
 869 
 870 // Helper class used to cache a ClassFileMap for the instance fields of
 871 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
 872 // heap iteration and avoid creating a field map for each object in the heap
 873 // (only need to create the map when the first instance of a class is encountered).
 874 //
 875 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
 876  private:
 877    enum {
 878      initial_class_count = 200
 879    };
 880   ClassFieldMap* _field_map;
 881 
 882   ClassFieldMap* field_map() const          { return _field_map; }
 883 
 884   JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
 885   ~JvmtiCachedClassFieldMap();
 886 
 887   static GrowableArray<InstanceKlass*>* _class_list;
 888   static void add_to_class_list(InstanceKlass* ik);
 889 
 890  public:
 891   // returns the field map for a given object (returning map cached
 892   // by InstanceKlass if possible
 893   static ClassFieldMap* get_map_of_instance_fields(oop obj);
 894 
 895   // removes the field map from all instanceKlasses - should be
 896   // called before VM operation completes
 897   static void clear_cache();
 898 
 899   // returns the number of ClassFieldMap cached by instanceKlasses
 900   static int cached_field_map_count();
 901 };
 902 
 903 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
 904 
 905 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
 906   _field_map = field_map;
 907 }
 908 
 909 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
 910   if (_field_map != NULL) {
 911     delete _field_map;
 912   }
 913 }
 914 
 915 // Marker class to ensure that the class file map cache is only used in a defined
 916 // scope.
 917 class ClassFieldMapCacheMark : public StackObj {
 918  private:
 919    static bool _is_active;
 920  public:
 921    ClassFieldMapCacheMark() {
 922      assert(Thread::current()->is_VM_thread(), "must be VMThread");
 923      assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
 924      assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
 925      _is_active = true;
 926    }
 927    ~ClassFieldMapCacheMark() {
 928      JvmtiCachedClassFieldMap::clear_cache();
 929      _is_active = false;
 930    }
 931    static bool is_active() { return _is_active; }
 932 };
 933 
 934 bool ClassFieldMapCacheMark::_is_active;
 935 
 936 
 937 // record that the given InstanceKlass is caching a field map
 938 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
 939   if (_class_list == NULL) {
 940     _class_list = new (ResourceObj::C_HEAP, mtInternal)
 941       GrowableArray<InstanceKlass*>(initial_class_count, true);
 942   }
 943   _class_list->push(ik);
 944 }
 945 
 946 // returns the instance field map for the given object
 947 // (returns field map cached by the InstanceKlass if possible)
 948 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
 949   assert(Thread::current()->is_VM_thread(), "must be VMThread");
 950   assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
 951 
 952   Klass* k = obj->klass();
 953   InstanceKlass* ik = InstanceKlass::cast(k);
 954 
 955   // return cached map if possible
 956   JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
 957   if (cached_map != NULL) {
 958     assert(cached_map->field_map() != NULL, "missing field list");
 959     return cached_map->field_map();
 960   } else {
 961     ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
 962     cached_map = new JvmtiCachedClassFieldMap(field_map);
 963     ik->set_jvmti_cached_class_field_map(cached_map);
 964     add_to_class_list(ik);
 965     return field_map;
 966   }
 967 }
 968 
 969 // remove the fields maps cached from all instanceKlasses
 970 void JvmtiCachedClassFieldMap::clear_cache() {
 971   assert(Thread::current()->is_VM_thread(), "must be VMThread");
 972   if (_class_list != NULL) {
 973     for (int i = 0; i < _class_list->length(); i++) {
 974       InstanceKlass* ik = _class_list->at(i);
 975       JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
 976       assert(cached_map != NULL, "should not be NULL");
 977       ik->set_jvmti_cached_class_field_map(NULL);
 978       delete cached_map;  // deletes the encapsulated field map
 979     }
 980     delete _class_list;
 981     _class_list = NULL;
 982   }
 983 }
 984 
 985 // returns the number of ClassFieldMap cached by instanceKlasses
 986 int JvmtiCachedClassFieldMap::cached_field_map_count() {
 987   return (_class_list == NULL) ? 0 : _class_list->length();
 988 }
 989 
 990 // helper function to indicate if an object is filtered by its tag or class tag
 991 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
 992                                               jlong klass_tag,
 993                                               int heap_filter) {
 994   // apply the heap filter
 995   if (obj_tag != 0) {
 996     // filter out tagged objects
 997     if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
 998   } else {
 999     // filter out untagged objects
1000     if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
1001   }
1002   if (klass_tag != 0) {
1003     // filter out objects with tagged classes
1004     if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1005   } else {
1006     // filter out objects with untagged classes.
1007     if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1008   }
1009   return false;
1010 }
1011 
1012 // helper function to indicate if an object is filtered by a klass filter
1013 static inline bool is_filtered_by_klass_filter(oop obj, Klass* klass_filter) {
1014   if (klass_filter != NULL) {
1015     if (obj->klass() != klass_filter) {
1016       return true;
1017     }
1018   }
1019   return false;
1020 }
1021 
1022 // helper function to tell if a field is a primitive field or not
1023 static inline bool is_primitive_field_type(char type) {
1024   return (type != 'L' && type != '[');
1025 }
1026 
1027 // helper function to copy the value from location addr to jvalue.
1028 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1029   switch (value_type) {
1030     case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1031     case JVMTI_PRIMITIVE_TYPE_BYTE    : { v->b = *(jbyte*)addr;    break; }
1032     case JVMTI_PRIMITIVE_TYPE_CHAR    : { v->c = *(jchar*)addr;    break; }
1033     case JVMTI_PRIMITIVE_TYPE_SHORT   : { v->s = *(jshort*)addr;   break; }
1034     case JVMTI_PRIMITIVE_TYPE_INT     : { v->i = *(jint*)addr;     break; }
1035     case JVMTI_PRIMITIVE_TYPE_LONG    : { v->j = *(jlong*)addr;    break; }
1036     case JVMTI_PRIMITIVE_TYPE_FLOAT   : { v->f = *(jfloat*)addr;   break; }
1037     case JVMTI_PRIMITIVE_TYPE_DOUBLE  : { v->d = *(jdouble*)addr;  break; }
1038     default: ShouldNotReachHere();
1039   }
1040 }
1041 
1042 // helper function to invoke string primitive value callback
1043 // returns visit control flags
1044 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1045                                          CallbackWrapper* wrapper,
1046                                          oop str,
1047                                          void* user_data)
1048 {
1049   assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1050 
1051   typeArrayOop s_value = java_lang_String::value(str);
1052 
1053   // JDK-6584008: the value field may be null if a String instance is
1054   // partially constructed.
1055   if (s_value == NULL) {
1056     return 0;
1057   }
1058   // get the string value and length
1059   // (string value may be offset from the base)
1060   int s_len = java_lang_String::length(str);
1061   bool is_latin1 = java_lang_String::is_latin1(str);
1062   jchar* value;
1063   if (s_len > 0) {
1064     if (!is_latin1) {
1065       value = s_value->char_at_addr(0);
1066     } else {
1067       // Inflate latin1 encoded string to UTF16
1068       jchar* buf = NEW_C_HEAP_ARRAY(jchar, s_len, mtInternal);
1069       for (int i = 0; i < s_len; i++) {
1070         buf[i] = ((jchar) s_value->byte_at(i)) & 0xff;
1071       }
1072       value = &buf[0];
1073     }
1074   } else {
1075     // Don't use char_at_addr(0) if length is 0
1076     value = (jchar*) s_value->base(T_CHAR);
1077   }
1078 
1079   // invoke the callback
1080   jint res = (*cb)(wrapper->klass_tag(),
1081                    wrapper->obj_size(),
1082                    wrapper->obj_tag_p(),
1083                    value,
1084                    (jint)s_len,
1085                    user_data);
1086 
1087   if (is_latin1 && s_len > 0) {
1088     FREE_C_HEAP_ARRAY(jchar, value);
1089   }
1090   return res;
1091 }
1092 
1093 // helper function to invoke string primitive value callback
1094 // returns visit control flags
1095 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1096                                                   CallbackWrapper* wrapper,
1097                                                   oop obj,
1098                                                   void* user_data)
1099 {
1100   assert(obj->is_typeArray(), "not a primitive array");
1101 
1102   // get base address of first element
1103   typeArrayOop array = typeArrayOop(obj);
1104   BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
1105   void* elements = array->base(type);
1106 
1107   // jvmtiPrimitiveType is defined so this mapping is always correct
1108   jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1109 
1110   return (*cb)(wrapper->klass_tag(),
1111                wrapper->obj_size(),
1112                wrapper->obj_tag_p(),
1113                (jint)array->length(),
1114                elem_type,
1115                elements,
1116                user_data);
1117 }
1118 
1119 // helper function to invoke the primitive field callback for all static fields
1120 // of a given class
1121 static jint invoke_primitive_field_callback_for_static_fields
1122   (CallbackWrapper* wrapper,
1123    oop obj,
1124    jvmtiPrimitiveFieldCallback cb,
1125    void* user_data)
1126 {
1127   // for static fields only the index will be set
1128   static jvmtiHeapReferenceInfo reference_info = { 0 };
1129 
1130   assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1131   if (java_lang_Class::is_primitive(obj)) {
1132     return 0;
1133   }
1134   Klass* klass = java_lang_Class::as_Klass(obj);
1135 
1136   // ignore classes for object and type arrays
1137   if (!klass->is_instance_klass()) {
1138     return 0;
1139   }
1140 
1141   // ignore classes which aren't linked yet
1142   InstanceKlass* ik = InstanceKlass::cast(klass);
1143   if (!ik->is_linked()) {
1144     return 0;
1145   }
1146 
1147   // get the field map
1148   ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1149 
1150   // invoke the callback for each static primitive field
1151   for (int i=0; i<field_map->field_count(); i++) {
1152     ClassFieldDescriptor* field = field_map->field_at(i);
1153 
1154     // ignore non-primitive fields
1155     char type = field->field_type();
1156     if (!is_primitive_field_type(type)) {
1157       continue;
1158     }
1159     // one-to-one mapping
1160     jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1161 
1162     // get offset and field value
1163     int offset = field->field_offset();
1164     address addr = (address)klass->java_mirror() + offset;
1165     jvalue value;
1166     copy_to_jvalue(&value, addr, value_type);
1167 
1168     // field index
1169     reference_info.field.index = field->field_index();
1170 
1171     // invoke the callback
1172     jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1173                      &reference_info,
1174                      wrapper->klass_tag(),
1175                      wrapper->obj_tag_p(),
1176                      value,
1177                      value_type,
1178                      user_data);
1179     if (res & JVMTI_VISIT_ABORT) {
1180       delete field_map;
1181       return res;
1182     }
1183   }
1184 
1185   delete field_map;
1186   return 0;
1187 }
1188 
1189 // helper function to invoke the primitive field callback for all instance fields
1190 // of a given object
1191 static jint invoke_primitive_field_callback_for_instance_fields(
1192   CallbackWrapper* wrapper,
1193   oop obj,
1194   jvmtiPrimitiveFieldCallback cb,
1195   void* user_data)
1196 {
1197   // for instance fields only the index will be set
1198   static jvmtiHeapReferenceInfo reference_info = { 0 };
1199 
1200   // get the map of the instance fields
1201   ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1202 
1203   // invoke the callback for each instance primitive field
1204   for (int i=0; i<fields->field_count(); i++) {
1205     ClassFieldDescriptor* field = fields->field_at(i);
1206 
1207     // ignore non-primitive fields
1208     char type = field->field_type();
1209     if (!is_primitive_field_type(type)) {
1210       continue;
1211     }
1212     // one-to-one mapping
1213     jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1214 
1215     // get offset and field value
1216     int offset = field->field_offset();
1217     address addr = (address)obj + offset;
1218     jvalue value;
1219     copy_to_jvalue(&value, addr, value_type);
1220 
1221     // field index
1222     reference_info.field.index = field->field_index();
1223 
1224     // invoke the callback
1225     jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1226                      &reference_info,
1227                      wrapper->klass_tag(),
1228                      wrapper->obj_tag_p(),
1229                      value,
1230                      value_type,
1231                      user_data);
1232     if (res & JVMTI_VISIT_ABORT) {
1233       return res;
1234     }
1235   }
1236   return 0;
1237 }
1238 
1239 
1240 // VM operation to iterate over all objects in the heap (both reachable
1241 // and unreachable)
1242 class VM_HeapIterateOperation: public VM_Operation {
1243  private:
1244   ObjectClosure* _blk;
1245  public:
1246   VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1247 
1248   VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1249   void doit() {
1250     // allows class files maps to be cached during iteration
1251     ClassFieldMapCacheMark cm;
1252 
1253     // make sure that heap is parsable (fills TLABs with filler objects)
1254     Universe::heap()->ensure_parsability(false);  // no need to retire TLABs
1255 
1256     // Verify heap before iteration - if the heap gets corrupted then
1257     // JVMTI's IterateOverHeap will crash.
1258     if (VerifyBeforeIteration) {
1259       Universe::verify();
1260     }
1261 
1262     // do the iteration
1263     // If this operation encounters a bad object when using CMS,
1264     // consider using safe_object_iterate() which avoids perm gen
1265     // objects that may contain bad references.
1266     Universe::heap()->object_iterate(_blk);
1267   }
1268 
1269 };
1270 
1271 
1272 // An ObjectClosure used to support the deprecated IterateOverHeap and
1273 // IterateOverInstancesOfClass functions
1274 class IterateOverHeapObjectClosure: public ObjectClosure {
1275  private:
1276   JvmtiTagMap* _tag_map;
1277   Klass* _klass;
1278   jvmtiHeapObjectFilter _object_filter;
1279   jvmtiHeapObjectCallback _heap_object_callback;
1280   const void* _user_data;
1281 
1282   // accessors
1283   JvmtiTagMap* tag_map() const                    { return _tag_map; }
1284   jvmtiHeapObjectFilter object_filter() const     { return _object_filter; }
1285   jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1286   Klass* klass() const                            { return _klass; }
1287   const void* user_data() const                   { return _user_data; }
1288 
1289   // indicates if iteration has been aborted
1290   bool _iteration_aborted;
1291   bool is_iteration_aborted() const               { return _iteration_aborted; }
1292   void set_iteration_aborted(bool aborted)        { _iteration_aborted = aborted; }
1293 
1294  public:
1295   IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1296                                Klass* klass,
1297                                jvmtiHeapObjectFilter object_filter,
1298                                jvmtiHeapObjectCallback heap_object_callback,
1299                                const void* user_data) :
1300     _tag_map(tag_map),
1301     _klass(klass),
1302     _object_filter(object_filter),
1303     _heap_object_callback(heap_object_callback),
1304     _user_data(user_data),
1305     _iteration_aborted(false)
1306   {
1307   }
1308 
1309   void do_object(oop o);
1310 };
1311 
1312 // invoked for each object in the heap
1313 void IterateOverHeapObjectClosure::do_object(oop o) {
1314   // check if iteration has been halted
1315   if (is_iteration_aborted()) return;
1316 
1317   // ignore any objects that aren't visible to profiler
1318   if (!ServiceUtil::visible_oop(o)) return;
1319 
1320   // instanceof check when filtering by klass
1321   if (klass() != NULL && !o->is_a(klass())) {
1322     return;
1323   }
1324   // prepare for the calllback
1325   CallbackWrapper wrapper(tag_map(), o);
1326 
1327   // if the object is tagged and we're only interested in untagged objects
1328   // then don't invoke the callback. Similiarly, if the object is untagged
1329   // and we're only interested in tagged objects we skip the callback.
1330   if (wrapper.obj_tag() != 0) {
1331     if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1332   } else {
1333     if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1334   }
1335 
1336   // invoke the agent's callback
1337   jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1338                                                        wrapper.obj_size(),
1339                                                        wrapper.obj_tag_p(),
1340                                                        (void*)user_data());
1341   if (control == JVMTI_ITERATION_ABORT) {
1342     set_iteration_aborted(true);
1343   }
1344 }
1345 
1346 // An ObjectClosure used to support the IterateThroughHeap function
1347 class IterateThroughHeapObjectClosure: public ObjectClosure {
1348  private:
1349   JvmtiTagMap* _tag_map;
1350   Klass* _klass;
1351   int _heap_filter;
1352   const jvmtiHeapCallbacks* _callbacks;
1353   const void* _user_data;
1354 
1355   // accessor functions
1356   JvmtiTagMap* tag_map() const                     { return _tag_map; }
1357   int heap_filter() const                          { return _heap_filter; }
1358   const jvmtiHeapCallbacks* callbacks() const      { return _callbacks; }
1359   Klass* klass() const                             { return _klass; }
1360   const void* user_data() const                    { return _user_data; }
1361 
1362   // indicates if the iteration has been aborted
1363   bool _iteration_aborted;
1364   bool is_iteration_aborted() const                { return _iteration_aborted; }
1365 
1366   // used to check the visit control flags. If the abort flag is set
1367   // then we set the iteration aborted flag so that the iteration completes
1368   // without processing any further objects
1369   bool check_flags_for_abort(jint flags) {
1370     bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1371     if (is_abort) {
1372       _iteration_aborted = true;
1373     }
1374     return is_abort;
1375   }
1376 
1377  public:
1378   IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1379                                   Klass* klass,
1380                                   int heap_filter,
1381                                   const jvmtiHeapCallbacks* heap_callbacks,
1382                                   const void* user_data) :
1383     _tag_map(tag_map),
1384     _klass(klass),
1385     _heap_filter(heap_filter),
1386     _callbacks(heap_callbacks),
1387     _user_data(user_data),
1388     _iteration_aborted(false)
1389   {
1390   }
1391 
1392   void do_object(oop o);
1393 };
1394 
1395 // invoked for each object in the heap
1396 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1397   // check if iteration has been halted
1398   if (is_iteration_aborted()) return;
1399 
1400   // ignore any objects that aren't visible to profiler
1401   if (!ServiceUtil::visible_oop(obj)) return;
1402 
1403   // apply class filter
1404   if (is_filtered_by_klass_filter(obj, klass())) return;
1405 
1406   // prepare for callback
1407   CallbackWrapper wrapper(tag_map(), obj);
1408 
1409   // check if filtered by the heap filter
1410   if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1411     return;
1412   }
1413 
1414   // for arrays we need the length, otherwise -1
1415   bool is_array = obj->is_array();
1416   int len = is_array ? arrayOop(obj)->length() : -1;
1417 
1418   // invoke the object callback (if callback is provided)
1419   if (callbacks()->heap_iteration_callback != NULL) {
1420     jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1421     jint res = (*cb)(wrapper.klass_tag(),
1422                      wrapper.obj_size(),
1423                      wrapper.obj_tag_p(),
1424                      (jint)len,
1425                      (void*)user_data());
1426     if (check_flags_for_abort(res)) return;
1427   }
1428 
1429   // for objects and classes we report primitive fields if callback provided
1430   if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1431     jint res;
1432     jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1433     if (obj->klass() == SystemDictionary::Class_klass()) {
1434       res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1435                                                                     obj,
1436                                                                     cb,
1437                                                                     (void*)user_data());
1438     } else {
1439       res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1440                                                                       obj,
1441                                                                       cb,
1442                                                                       (void*)user_data());
1443     }
1444     if (check_flags_for_abort(res)) return;
1445   }
1446 
1447   // string callback
1448   if (!is_array &&
1449       callbacks()->string_primitive_value_callback != NULL &&
1450       obj->klass() == SystemDictionary::String_klass()) {
1451     jint res = invoke_string_value_callback(
1452                 callbacks()->string_primitive_value_callback,
1453                 &wrapper,
1454                 obj,
1455                 (void*)user_data() );
1456     if (check_flags_for_abort(res)) return;
1457   }
1458 
1459   // array callback
1460   if (is_array &&
1461       callbacks()->array_primitive_value_callback != NULL &&
1462       obj->is_typeArray()) {
1463     jint res = invoke_array_primitive_value_callback(
1464                callbacks()->array_primitive_value_callback,
1465                &wrapper,
1466                obj,
1467                (void*)user_data() );
1468     if (check_flags_for_abort(res)) return;
1469   }
1470 };
1471 
1472 
1473 // Deprecated function to iterate over all objects in the heap
1474 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1475                                     Klass* klass,
1476                                     jvmtiHeapObjectCallback heap_object_callback,
1477                                     const void* user_data)
1478 {
1479   MutexLocker ml(Heap_lock);
1480   IterateOverHeapObjectClosure blk(this,
1481                                    klass,
1482                                    object_filter,
1483                                    heap_object_callback,
1484                                    user_data);
1485   VM_HeapIterateOperation op(&blk);
1486   VMThread::execute(&op);
1487 }
1488 
1489 
1490 // Iterates over all objects in the heap
1491 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1492                                        Klass* klass,
1493                                        const jvmtiHeapCallbacks* callbacks,
1494                                        const void* user_data)
1495 {
1496   MutexLocker ml(Heap_lock);
1497   IterateThroughHeapObjectClosure blk(this,
1498                                       klass,
1499                                       heap_filter,
1500                                       callbacks,
1501                                       user_data);
1502   VM_HeapIterateOperation op(&blk);
1503   VMThread::execute(&op);
1504 }
1505 
1506 // support class for get_objects_with_tags
1507 
1508 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1509  private:
1510   JvmtiEnv* _env;
1511   jlong* _tags;
1512   jint _tag_count;
1513 
1514   GrowableArray<jobject>* _object_results;  // collected objects (JNI weak refs)
1515   GrowableArray<uint64_t>* _tag_results;    // collected tags
1516 
1517  public:
1518   TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1519     _env = env;
1520     _tags = (jlong*)tags;
1521     _tag_count = tag_count;
1522     _object_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<jobject>(1,true);
1523     _tag_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<uint64_t>(1,true);
1524   }
1525 
1526   ~TagObjectCollector() {
1527     delete _object_results;
1528     delete _tag_results;
1529   }
1530 
1531   // for each tagged object check if the tag value matches
1532   // - if it matches then we create a JNI local reference to the object
1533   // and record the reference and tag value.
1534   //
1535   void do_entry(JvmtiTagHashmapEntry* entry) {
1536     for (int i=0; i<_tag_count; i++) {
1537       if (_tags[i] == entry->tag()) {
1538         oop o = entry->object();
1539         assert(o != NULL && Universe::heap()->is_in_reserved(o), "sanity check");
1540 #if INCLUDE_ALL_GCS
1541         if (UseG1GC) {
1542           // The reference in this tag map could be the only (implicitly weak)
1543           // reference to that object. If we hand it out, we need to keep it live wrt
1544           // SATB marking similar to other j.l.ref.Reference referents.
1545           G1SATBCardTableModRefBS::enqueue(o);
1546         }
1547 #endif
1548         jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1549         _object_results->append(ref);
1550         _tag_results->append((uint64_t)entry->tag());
1551       }
1552     }
1553   }
1554 
1555   // return the results from the collection
1556   //
1557   jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1558     jvmtiError error;
1559     int count = _object_results->length();
1560     assert(count >= 0, "sanity check");
1561 
1562     // if object_result_ptr is not NULL then allocate the result and copy
1563     // in the object references.
1564     if (object_result_ptr != NULL) {
1565       error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1566       if (error != JVMTI_ERROR_NONE) {
1567         return error;
1568       }
1569       for (int i=0; i<count; i++) {
1570         (*object_result_ptr)[i] = _object_results->at(i);
1571       }
1572     }
1573 
1574     // if tag_result_ptr is not NULL then allocate the result and copy
1575     // in the tag values.
1576     if (tag_result_ptr != NULL) {
1577       error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1578       if (error != JVMTI_ERROR_NONE) {
1579         if (object_result_ptr != NULL) {
1580           _env->Deallocate((unsigned char*)object_result_ptr);
1581         }
1582         return error;
1583       }
1584       for (int i=0; i<count; i++) {
1585         (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1586       }
1587     }
1588 
1589     *count_ptr = count;
1590     return JVMTI_ERROR_NONE;
1591   }
1592 };
1593 
1594 // return the list of objects with the specified tags
1595 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1596   jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1597 
1598   TagObjectCollector collector(env(), tags, count);
1599   {
1600     // iterate over all tagged objects
1601     MutexLocker ml(lock());
1602     entry_iterate(&collector);
1603   }
1604   return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1605 }
1606 
1607 
1608 // ObjectMarker is used to support the marking objects when walking the
1609 // heap.
1610 //
1611 // This implementation uses the existing mark bits in an object for
1612 // marking. Objects that are marked must later have their headers restored.
1613 // As most objects are unlocked and don't have their identity hash computed
1614 // we don't have to save their headers. Instead we save the headers that
1615 // are "interesting". Later when the headers are restored this implementation
1616 // restores all headers to their initial value and then restores the few
1617 // objects that had interesting headers.
1618 //
1619 // Future work: This implementation currently uses growable arrays to save
1620 // the oop and header of interesting objects. As an optimization we could
1621 // use the same technique as the GC and make use of the unused area
1622 // between top() and end().
1623 //
1624 
1625 // An ObjectClosure used to restore the mark bits of an object
1626 class RestoreMarksClosure : public ObjectClosure {
1627  public:
1628   void do_object(oop o) {
1629     if (o != NULL) {
1630       markOop mark = o->mark();
1631       if (mark->is_marked()) {
1632         o->init_mark();
1633       }
1634     }
1635   }
1636 };
1637 
1638 // ObjectMarker provides the mark and visited functions
1639 class ObjectMarker : AllStatic {
1640  private:
1641   // saved headers
1642   static GrowableArray<oop>* _saved_oop_stack;
1643   static GrowableArray<markOop>* _saved_mark_stack;
1644   static bool _needs_reset;                  // do we need to reset mark bits?
1645 
1646  public:
1647   static void init();                       // initialize
1648   static void done();                       // clean-up
1649 
1650   static inline void mark(oop o);           // mark an object
1651   static inline bool visited(oop o);        // check if object has been visited
1652 
1653   static inline bool needs_reset()            { return _needs_reset; }
1654   static inline void set_needs_reset(bool v)  { _needs_reset = v; }
1655 };
1656 
1657 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1658 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1659 bool ObjectMarker::_needs_reset = true;  // need to reset mark bits by default
1660 
1661 // initialize ObjectMarker - prepares for object marking
1662 void ObjectMarker::init() {
1663   assert(Thread::current()->is_VM_thread(), "must be VMThread");
1664 
1665   // prepare heap for iteration
1666   Universe::heap()->ensure_parsability(false);  // no need to retire TLABs
1667 
1668   // create stacks for interesting headers
1669   _saved_mark_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<markOop>(4000, true);
1670   _saved_oop_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(4000, true);
1671 
1672   if (UseBiasedLocking) {
1673     BiasedLocking::preserve_marks();
1674   }
1675 }
1676 
1677 // Object marking is done so restore object headers
1678 void ObjectMarker::done() {
1679   // iterate over all objects and restore the mark bits to
1680   // their initial value
1681   RestoreMarksClosure blk;
1682   if (needs_reset()) {
1683     Universe::heap()->object_iterate(&blk);
1684   } else {
1685     // We don't need to reset mark bits on this call, but reset the
1686     // flag to the default for the next call.
1687     set_needs_reset(true);
1688   }
1689 
1690   // now restore the interesting headers
1691   for (int i = 0; i < _saved_oop_stack->length(); i++) {
1692     oop o = _saved_oop_stack->at(i);
1693     markOop mark = _saved_mark_stack->at(i);
1694     o->set_mark(mark);
1695   }
1696 
1697   if (UseBiasedLocking) {
1698     BiasedLocking::restore_marks();
1699   }
1700 
1701   // free the stacks
1702   delete _saved_oop_stack;
1703   delete _saved_mark_stack;
1704 }
1705 
1706 // mark an object
1707 inline void ObjectMarker::mark(oop o) {
1708   assert(Universe::heap()->is_in(o), "sanity check");
1709   assert(!o->mark()->is_marked(), "should only mark an object once");
1710 
1711   // object's mark word
1712   markOop mark = o->mark();
1713 
1714   if (mark->must_be_preserved(o)) {
1715     _saved_mark_stack->push(mark);
1716     _saved_oop_stack->push(o);
1717   }
1718 
1719   // mark the object
1720   o->set_mark(markOopDesc::prototype()->set_marked());
1721 }
1722 
1723 // return true if object is marked
1724 inline bool ObjectMarker::visited(oop o) {
1725   return o->mark()->is_marked();
1726 }
1727 
1728 // Stack allocated class to help ensure that ObjectMarker is used
1729 // correctly. Constructor initializes ObjectMarker, destructor calls
1730 // ObjectMarker's done() function to restore object headers.
1731 class ObjectMarkerController : public StackObj {
1732  public:
1733   ObjectMarkerController() {
1734     ObjectMarker::init();
1735   }
1736   ~ObjectMarkerController() {
1737     ObjectMarker::done();
1738   }
1739 };
1740 
1741 
1742 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1743 // (not performance critical as only used for roots)
1744 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1745   switch (kind) {
1746     case JVMTI_HEAP_REFERENCE_JNI_GLOBAL:   return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1747     case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1748     case JVMTI_HEAP_REFERENCE_MONITOR:      return JVMTI_HEAP_ROOT_MONITOR;
1749     case JVMTI_HEAP_REFERENCE_STACK_LOCAL:  return JVMTI_HEAP_ROOT_STACK_LOCAL;
1750     case JVMTI_HEAP_REFERENCE_JNI_LOCAL:    return JVMTI_HEAP_ROOT_JNI_LOCAL;
1751     case JVMTI_HEAP_REFERENCE_THREAD:       return JVMTI_HEAP_ROOT_THREAD;
1752     case JVMTI_HEAP_REFERENCE_OTHER:        return JVMTI_HEAP_ROOT_OTHER;
1753     default: ShouldNotReachHere();          return JVMTI_HEAP_ROOT_OTHER;
1754   }
1755 }
1756 
1757 // Base class for all heap walk contexts. The base class maintains a flag
1758 // to indicate if the context is valid or not.
1759 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1760  private:
1761   bool _valid;
1762  public:
1763   HeapWalkContext(bool valid)                   { _valid = valid; }
1764   void invalidate()                             { _valid = false; }
1765   bool is_valid() const                         { return _valid; }
1766 };
1767 
1768 // A basic heap walk context for the deprecated heap walking functions.
1769 // The context for a basic heap walk are the callbacks and fields used by
1770 // the referrer caching scheme.
1771 class BasicHeapWalkContext: public HeapWalkContext {
1772  private:
1773   jvmtiHeapRootCallback _heap_root_callback;
1774   jvmtiStackReferenceCallback _stack_ref_callback;
1775   jvmtiObjectReferenceCallback _object_ref_callback;
1776 
1777   // used for caching
1778   oop _last_referrer;
1779   jlong _last_referrer_tag;
1780 
1781  public:
1782   BasicHeapWalkContext() : HeapWalkContext(false) { }
1783 
1784   BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1785                        jvmtiStackReferenceCallback stack_ref_callback,
1786                        jvmtiObjectReferenceCallback object_ref_callback) :
1787     HeapWalkContext(true),
1788     _heap_root_callback(heap_root_callback),
1789     _stack_ref_callback(stack_ref_callback),
1790     _object_ref_callback(object_ref_callback),
1791     _last_referrer(NULL),
1792     _last_referrer_tag(0) {
1793   }
1794 
1795   // accessors
1796   jvmtiHeapRootCallback heap_root_callback() const         { return _heap_root_callback; }
1797   jvmtiStackReferenceCallback stack_ref_callback() const   { return _stack_ref_callback; }
1798   jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback;  }
1799 
1800   oop last_referrer() const               { return _last_referrer; }
1801   void set_last_referrer(oop referrer)    { _last_referrer = referrer; }
1802   jlong last_referrer_tag() const         { return _last_referrer_tag; }
1803   void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1804 };
1805 
1806 // The advanced heap walk context for the FollowReferences functions.
1807 // The context is the callbacks, and the fields used for filtering.
1808 class AdvancedHeapWalkContext: public HeapWalkContext {
1809  private:
1810   jint _heap_filter;
1811   Klass* _klass_filter;
1812   const jvmtiHeapCallbacks* _heap_callbacks;
1813 
1814  public:
1815   AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1816 
1817   AdvancedHeapWalkContext(jint heap_filter,
1818                            Klass* klass_filter,
1819                            const jvmtiHeapCallbacks* heap_callbacks) :
1820     HeapWalkContext(true),
1821     _heap_filter(heap_filter),
1822     _klass_filter(klass_filter),
1823     _heap_callbacks(heap_callbacks) {
1824   }
1825 
1826   // accessors
1827   jint heap_filter() const         { return _heap_filter; }
1828   Klass* klass_filter() const      { return _klass_filter; }
1829 
1830   const jvmtiHeapReferenceCallback heap_reference_callback() const {
1831     return _heap_callbacks->heap_reference_callback;
1832   };
1833   const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1834     return _heap_callbacks->primitive_field_callback;
1835   }
1836   const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1837     return _heap_callbacks->array_primitive_value_callback;
1838   }
1839   const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1840     return _heap_callbacks->string_primitive_value_callback;
1841   }
1842 };
1843 
1844 // The CallbackInvoker is a class with static functions that the heap walk can call
1845 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1846 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1847 // mode is for the newer FollowReferences function which supports a lot of
1848 // additional callbacks.
1849 class CallbackInvoker : AllStatic {
1850  private:
1851   // heap walk styles
1852   enum { basic, advanced };
1853   static int _heap_walk_type;
1854   static bool is_basic_heap_walk()           { return _heap_walk_type == basic; }
1855   static bool is_advanced_heap_walk()        { return _heap_walk_type == advanced; }
1856 
1857   // context for basic style heap walk
1858   static BasicHeapWalkContext _basic_context;
1859   static BasicHeapWalkContext* basic_context() {
1860     assert(_basic_context.is_valid(), "invalid");
1861     return &_basic_context;
1862   }
1863 
1864   // context for advanced style heap walk
1865   static AdvancedHeapWalkContext _advanced_context;
1866   static AdvancedHeapWalkContext* advanced_context() {
1867     assert(_advanced_context.is_valid(), "invalid");
1868     return &_advanced_context;
1869   }
1870 
1871   // context needed for all heap walks
1872   static JvmtiTagMap* _tag_map;
1873   static const void* _user_data;
1874   static GrowableArray<oop>* _visit_stack;
1875 
1876   // accessors
1877   static JvmtiTagMap* tag_map()                        { return _tag_map; }
1878   static const void* user_data()                       { return _user_data; }
1879   static GrowableArray<oop>* visit_stack()             { return _visit_stack; }
1880 
1881   // if the object hasn't been visited then push it onto the visit stack
1882   // so that it will be visited later
1883   static inline bool check_for_visit(oop obj) {
1884     if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1885     return true;
1886   }
1887 
1888   // invoke basic style callbacks
1889   static inline bool invoke_basic_heap_root_callback
1890     (jvmtiHeapRootKind root_kind, oop obj);
1891   static inline bool invoke_basic_stack_ref_callback
1892     (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1893      int slot, oop obj);
1894   static inline bool invoke_basic_object_reference_callback
1895     (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1896 
1897   // invoke advanced style callbacks
1898   static inline bool invoke_advanced_heap_root_callback
1899     (jvmtiHeapReferenceKind ref_kind, oop obj);
1900   static inline bool invoke_advanced_stack_ref_callback
1901     (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1902      jmethodID method, jlocation bci, jint slot, oop obj);
1903   static inline bool invoke_advanced_object_reference_callback
1904     (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1905 
1906   // used to report the value of primitive fields
1907   static inline bool report_primitive_field
1908     (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1909 
1910  public:
1911   // initialize for basic mode
1912   static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1913                                              GrowableArray<oop>* visit_stack,
1914                                              const void* user_data,
1915                                              BasicHeapWalkContext context);
1916 
1917   // initialize for advanced mode
1918   static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1919                                                 GrowableArray<oop>* visit_stack,
1920                                                 const void* user_data,
1921                                                 AdvancedHeapWalkContext context);
1922 
1923    // functions to report roots
1924   static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
1925   static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1926     jmethodID m, oop o);
1927   static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1928     jmethodID method, jlocation bci, jint slot, oop o);
1929 
1930   // functions to report references
1931   static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
1932   static inline bool report_class_reference(oop referrer, oop referree);
1933   static inline bool report_class_loader_reference(oop referrer, oop referree);
1934   static inline bool report_signers_reference(oop referrer, oop referree);
1935   static inline bool report_protection_domain_reference(oop referrer, oop referree);
1936   static inline bool report_superclass_reference(oop referrer, oop referree);
1937   static inline bool report_interface_reference(oop referrer, oop referree);
1938   static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
1939   static inline bool report_field_reference(oop referrer, oop referree, jint slot);
1940   static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
1941   static inline bool report_primitive_array_values(oop array);
1942   static inline bool report_string_value(oop str);
1943   static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
1944   static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
1945 };
1946 
1947 // statics
1948 int CallbackInvoker::_heap_walk_type;
1949 BasicHeapWalkContext CallbackInvoker::_basic_context;
1950 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1951 JvmtiTagMap* CallbackInvoker::_tag_map;
1952 const void* CallbackInvoker::_user_data;
1953 GrowableArray<oop>* CallbackInvoker::_visit_stack;
1954 
1955 // initialize for basic heap walk (IterateOverReachableObjects et al)
1956 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1957                                                      GrowableArray<oop>* visit_stack,
1958                                                      const void* user_data,
1959                                                      BasicHeapWalkContext context) {
1960   _tag_map = tag_map;
1961   _visit_stack = visit_stack;
1962   _user_data = user_data;
1963   _basic_context = context;
1964   _advanced_context.invalidate();       // will trigger assertion if used
1965   _heap_walk_type = basic;
1966 }
1967 
1968 // initialize for advanced heap walk (FollowReferences)
1969 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1970                                                         GrowableArray<oop>* visit_stack,
1971                                                         const void* user_data,
1972                                                         AdvancedHeapWalkContext context) {
1973   _tag_map = tag_map;
1974   _visit_stack = visit_stack;
1975   _user_data = user_data;
1976   _advanced_context = context;
1977   _basic_context.invalidate();      // will trigger assertion if used
1978   _heap_walk_type = advanced;
1979 }
1980 
1981 
1982 // invoke basic style heap root callback
1983 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
1984   assert(ServiceUtil::visible_oop(obj), "checking");
1985 
1986   // if we heap roots should be reported
1987   jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1988   if (cb == NULL) {
1989     return check_for_visit(obj);
1990   }
1991 
1992   CallbackWrapper wrapper(tag_map(), obj);
1993   jvmtiIterationControl control = (*cb)(root_kind,
1994                                         wrapper.klass_tag(),
1995                                         wrapper.obj_size(),
1996                                         wrapper.obj_tag_p(),
1997                                         (void*)user_data());
1998   // push root to visit stack when following references
1999   if (control == JVMTI_ITERATION_CONTINUE &&
2000       basic_context()->object_ref_callback() != NULL) {
2001     visit_stack()->push(obj);
2002   }
2003   return control != JVMTI_ITERATION_ABORT;
2004 }
2005 
2006 // invoke basic style stack ref callback
2007 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
2008                                                              jlong thread_tag,
2009                                                              jint depth,
2010                                                              jmethodID method,
2011                                                              int slot,
2012                                                              oop obj) {
2013   assert(ServiceUtil::visible_oop(obj), "checking");
2014 
2015   // if we stack refs should be reported
2016   jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
2017   if (cb == NULL) {
2018     return check_for_visit(obj);
2019   }
2020 
2021   CallbackWrapper wrapper(tag_map(), obj);
2022   jvmtiIterationControl control = (*cb)(root_kind,
2023                                         wrapper.klass_tag(),
2024                                         wrapper.obj_size(),
2025                                         wrapper.obj_tag_p(),
2026                                         thread_tag,
2027                                         depth,
2028                                         method,
2029                                         slot,
2030                                         (void*)user_data());
2031   // push root to visit stack when following references
2032   if (control == JVMTI_ITERATION_CONTINUE &&
2033       basic_context()->object_ref_callback() != NULL) {
2034     visit_stack()->push(obj);
2035   }
2036   return control != JVMTI_ITERATION_ABORT;
2037 }
2038 
2039 // invoke basic style object reference callback
2040 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2041                                                                     oop referrer,
2042                                                                     oop referree,
2043                                                                     jint index) {
2044 
2045   assert(ServiceUtil::visible_oop(referrer), "checking");
2046   assert(ServiceUtil::visible_oop(referree), "checking");
2047 
2048   BasicHeapWalkContext* context = basic_context();
2049 
2050   // callback requires the referrer's tag. If it's the same referrer
2051   // as the last call then we use the cached value.
2052   jlong referrer_tag;
2053   if (referrer == context->last_referrer()) {
2054     referrer_tag = context->last_referrer_tag();
2055   } else {
2056     referrer_tag = tag_for(tag_map(), referrer);
2057   }
2058 
2059   // do the callback
2060   CallbackWrapper wrapper(tag_map(), referree);
2061   jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2062   jvmtiIterationControl control = (*cb)(ref_kind,
2063                                         wrapper.klass_tag(),
2064                                         wrapper.obj_size(),
2065                                         wrapper.obj_tag_p(),
2066                                         referrer_tag,
2067                                         index,
2068                                         (void*)user_data());
2069 
2070   // record referrer and referrer tag. For self-references record the
2071   // tag value from the callback as this might differ from referrer_tag.
2072   context->set_last_referrer(referrer);
2073   if (referrer == referree) {
2074     context->set_last_referrer_tag(*wrapper.obj_tag_p());
2075   } else {
2076     context->set_last_referrer_tag(referrer_tag);
2077   }
2078 
2079   if (control == JVMTI_ITERATION_CONTINUE) {
2080     return check_for_visit(referree);
2081   } else {
2082     return control != JVMTI_ITERATION_ABORT;
2083   }
2084 }
2085 
2086 // invoke advanced style heap root callback
2087 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2088                                                                 oop obj) {
2089   assert(ServiceUtil::visible_oop(obj), "checking");
2090 
2091   AdvancedHeapWalkContext* context = advanced_context();
2092 
2093   // check that callback is provided
2094   jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2095   if (cb == NULL) {
2096     return check_for_visit(obj);
2097   }
2098 
2099   // apply class filter
2100   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2101     return check_for_visit(obj);
2102   }
2103 
2104   // setup the callback wrapper
2105   CallbackWrapper wrapper(tag_map(), obj);
2106 
2107   // apply tag filter
2108   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2109                                  wrapper.klass_tag(),
2110                                  context->heap_filter())) {
2111     return check_for_visit(obj);
2112   }
2113 
2114   // for arrays we need the length, otherwise -1
2115   jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2116 
2117   // invoke the callback
2118   jint res  = (*cb)(ref_kind,
2119                     NULL, // referrer info
2120                     wrapper.klass_tag(),
2121                     0,    // referrer_class_tag is 0 for heap root
2122                     wrapper.obj_size(),
2123                     wrapper.obj_tag_p(),
2124                     NULL, // referrer_tag_p
2125                     len,
2126                     (void*)user_data());
2127   if (res & JVMTI_VISIT_ABORT) {
2128     return false;// referrer class tag
2129   }
2130   if (res & JVMTI_VISIT_OBJECTS) {
2131     check_for_visit(obj);
2132   }
2133   return true;
2134 }
2135 
2136 // report a reference from a thread stack to an object
2137 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2138                                                                 jlong thread_tag,
2139                                                                 jlong tid,
2140                                                                 int depth,
2141                                                                 jmethodID method,
2142                                                                 jlocation bci,
2143                                                                 jint slot,
2144                                                                 oop obj) {
2145   assert(ServiceUtil::visible_oop(obj), "checking");
2146 
2147   AdvancedHeapWalkContext* context = advanced_context();
2148 
2149   // check that callback is provider
2150   jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2151   if (cb == NULL) {
2152     return check_for_visit(obj);
2153   }
2154 
2155   // apply class filter
2156   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2157     return check_for_visit(obj);
2158   }
2159 
2160   // setup the callback wrapper
2161   CallbackWrapper wrapper(tag_map(), obj);
2162 
2163   // apply tag filter
2164   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2165                                  wrapper.klass_tag(),
2166                                  context->heap_filter())) {
2167     return check_for_visit(obj);
2168   }
2169 
2170   // setup the referrer info
2171   jvmtiHeapReferenceInfo reference_info;
2172   reference_info.stack_local.thread_tag = thread_tag;
2173   reference_info.stack_local.thread_id = tid;
2174   reference_info.stack_local.depth = depth;
2175   reference_info.stack_local.method = method;
2176   reference_info.stack_local.location = bci;
2177   reference_info.stack_local.slot = slot;
2178 
2179   // for arrays we need the length, otherwise -1
2180   jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2181 
2182   // call into the agent
2183   int res = (*cb)(ref_kind,
2184                   &reference_info,
2185                   wrapper.klass_tag(),
2186                   0,    // referrer_class_tag is 0 for heap root (stack)
2187                   wrapper.obj_size(),
2188                   wrapper.obj_tag_p(),
2189                   NULL, // referrer_tag is 0 for root
2190                   len,
2191                   (void*)user_data());
2192 
2193   if (res & JVMTI_VISIT_ABORT) {
2194     return false;
2195   }
2196   if (res & JVMTI_VISIT_OBJECTS) {
2197     check_for_visit(obj);
2198   }
2199   return true;
2200 }
2201 
2202 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2203 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2204 #define REF_INFO_MASK  ((1 << JVMTI_HEAP_REFERENCE_FIELD)         \
2205                       | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD)  \
2206                       | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2207                       | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2208                       | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL)   \
2209                       | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2210 
2211 // invoke the object reference callback to report a reference
2212 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2213                                                                        oop referrer,
2214                                                                        oop obj,
2215                                                                        jint index)
2216 {
2217   // field index is only valid field in reference_info
2218   static jvmtiHeapReferenceInfo reference_info = { 0 };
2219 
2220   assert(ServiceUtil::visible_oop(referrer), "checking");
2221   assert(ServiceUtil::visible_oop(obj), "checking");
2222 
2223   AdvancedHeapWalkContext* context = advanced_context();
2224 
2225   // check that callback is provider
2226   jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2227   if (cb == NULL) {
2228     return check_for_visit(obj);
2229   }
2230 
2231   // apply class filter
2232   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2233     return check_for_visit(obj);
2234   }
2235 
2236   // setup the callback wrapper
2237   TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2238 
2239   // apply tag filter
2240   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2241                                  wrapper.klass_tag(),
2242                                  context->heap_filter())) {
2243     return check_for_visit(obj);
2244   }
2245 
2246   // field index is only valid field in reference_info
2247   reference_info.field.index = index;
2248 
2249   // for arrays we need the length, otherwise -1
2250   jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2251 
2252   // invoke the callback
2253   int res = (*cb)(ref_kind,
2254                   (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2255                   wrapper.klass_tag(),
2256                   wrapper.referrer_klass_tag(),
2257                   wrapper.obj_size(),
2258                   wrapper.obj_tag_p(),
2259                   wrapper.referrer_tag_p(),
2260                   len,
2261                   (void*)user_data());
2262 
2263   if (res & JVMTI_VISIT_ABORT) {
2264     return false;
2265   }
2266   if (res & JVMTI_VISIT_OBJECTS) {
2267     check_for_visit(obj);
2268   }
2269   return true;
2270 }
2271 
2272 // report a "simple root"
2273 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2274   assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2275          kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2276   assert(ServiceUtil::visible_oop(obj), "checking");
2277 
2278   if (is_basic_heap_walk()) {
2279     // map to old style root kind
2280     jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2281     return invoke_basic_heap_root_callback(root_kind, obj);
2282   } else {
2283     assert(is_advanced_heap_walk(), "wrong heap walk type");
2284     return invoke_advanced_heap_root_callback(kind, obj);
2285   }
2286 }
2287 
2288 
2289 // invoke the primitive array values
2290 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2291   assert(obj->is_typeArray(), "not a primitive array");
2292 
2293   AdvancedHeapWalkContext* context = advanced_context();
2294   assert(context->array_primitive_value_callback() != NULL, "no callback");
2295 
2296   // apply class filter
2297   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2298     return true;
2299   }
2300 
2301   CallbackWrapper wrapper(tag_map(), obj);
2302 
2303   // apply tag filter
2304   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2305                                  wrapper.klass_tag(),
2306                                  context->heap_filter())) {
2307     return true;
2308   }
2309 
2310   // invoke the callback
2311   int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2312                                                   &wrapper,
2313                                                   obj,
2314                                                   (void*)user_data());
2315   return (!(res & JVMTI_VISIT_ABORT));
2316 }
2317 
2318 // invoke the string value callback
2319 inline bool CallbackInvoker::report_string_value(oop str) {
2320   assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2321 
2322   AdvancedHeapWalkContext* context = advanced_context();
2323   assert(context->string_primitive_value_callback() != NULL, "no callback");
2324 
2325   // apply class filter
2326   if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2327     return true;
2328   }
2329 
2330   CallbackWrapper wrapper(tag_map(), str);
2331 
2332   // apply tag filter
2333   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2334                                  wrapper.klass_tag(),
2335                                  context->heap_filter())) {
2336     return true;
2337   }
2338 
2339   // invoke the callback
2340   int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2341                                          &wrapper,
2342                                          str,
2343                                          (void*)user_data());
2344   return (!(res & JVMTI_VISIT_ABORT));
2345 }
2346 
2347 // invoke the primitive field callback
2348 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2349                                                     oop obj,
2350                                                     jint index,
2351                                                     address addr,
2352                                                     char type)
2353 {
2354   // for primitive fields only the index will be set
2355   static jvmtiHeapReferenceInfo reference_info = { 0 };
2356 
2357   AdvancedHeapWalkContext* context = advanced_context();
2358   assert(context->primitive_field_callback() != NULL, "no callback");
2359 
2360   // apply class filter
2361   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2362     return true;
2363   }
2364 
2365   CallbackWrapper wrapper(tag_map(), obj);
2366 
2367   // apply tag filter
2368   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2369                                  wrapper.klass_tag(),
2370                                  context->heap_filter())) {
2371     return true;
2372   }
2373 
2374   // the field index in the referrer
2375   reference_info.field.index = index;
2376 
2377   // map the type
2378   jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2379 
2380   // setup the jvalue
2381   jvalue value;
2382   copy_to_jvalue(&value, addr, value_type);
2383 
2384   jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2385   int res = (*cb)(ref_kind,
2386                   &reference_info,
2387                   wrapper.klass_tag(),
2388                   wrapper.obj_tag_p(),
2389                   value,
2390                   value_type,
2391                   (void*)user_data());
2392   return (!(res & JVMTI_VISIT_ABORT));
2393 }
2394 
2395 
2396 // instance field
2397 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2398                                                              jint index,
2399                                                              address value,
2400                                                              char type) {
2401   return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2402                                 obj,
2403                                 index,
2404                                 value,
2405                                 type);
2406 }
2407 
2408 // static field
2409 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2410                                                            jint index,
2411                                                            address value,
2412                                                            char type) {
2413   return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2414                                 obj,
2415                                 index,
2416                                 value,
2417                                 type);
2418 }
2419 
2420 // report a JNI local (root object) to the profiler
2421 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2422   if (is_basic_heap_walk()) {
2423     return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2424                                            thread_tag,
2425                                            depth,
2426                                            m,
2427                                            -1,
2428                                            obj);
2429   } else {
2430     return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2431                                               thread_tag, tid,
2432                                               depth,
2433                                               m,
2434                                               (jlocation)-1,
2435                                               -1,
2436                                               obj);
2437   }
2438 }
2439 
2440 
2441 // report a local (stack reference, root object)
2442 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2443                                                    jlong tid,
2444                                                    jint depth,
2445                                                    jmethodID method,
2446                                                    jlocation bci,
2447                                                    jint slot,
2448                                                    oop obj) {
2449   if (is_basic_heap_walk()) {
2450     return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2451                                            thread_tag,
2452                                            depth,
2453                                            method,
2454                                            slot,
2455                                            obj);
2456   } else {
2457     return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2458                                               thread_tag,
2459                                               tid,
2460                                               depth,
2461                                               method,
2462                                               bci,
2463                                               slot,
2464                                               obj);
2465   }
2466 }
2467 
2468 // report an object referencing a class.
2469 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2470   if (is_basic_heap_walk()) {
2471     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2472   } else {
2473     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2474   }
2475 }
2476 
2477 // report a class referencing its class loader.
2478 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2479   if (is_basic_heap_walk()) {
2480     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2481   } else {
2482     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2483   }
2484 }
2485 
2486 // report a class referencing its signers.
2487 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2488   if (is_basic_heap_walk()) {
2489     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2490   } else {
2491     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2492   }
2493 }
2494 
2495 // report a class referencing its protection domain..
2496 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2497   if (is_basic_heap_walk()) {
2498     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2499   } else {
2500     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2501   }
2502 }
2503 
2504 // report a class referencing its superclass.
2505 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2506   if (is_basic_heap_walk()) {
2507     // Send this to be consistent with past implementation
2508     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2509   } else {
2510     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2511   }
2512 }
2513 
2514 // report a class referencing one of its interfaces.
2515 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2516   if (is_basic_heap_walk()) {
2517     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2518   } else {
2519     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2520   }
2521 }
2522 
2523 // report a class referencing one of its static fields.
2524 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2525   if (is_basic_heap_walk()) {
2526     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2527   } else {
2528     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2529   }
2530 }
2531 
2532 // report an array referencing an element object
2533 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2534   if (is_basic_heap_walk()) {
2535     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2536   } else {
2537     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2538   }
2539 }
2540 
2541 // report an object referencing an instance field object
2542 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2543   if (is_basic_heap_walk()) {
2544     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2545   } else {
2546     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2547   }
2548 }
2549 
2550 // report an array referencing an element object
2551 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2552   if (is_basic_heap_walk()) {
2553     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2554   } else {
2555     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2556   }
2557 }
2558 
2559 // A supporting closure used to process simple roots
2560 class SimpleRootsClosure : public OopClosure {
2561  private:
2562   jvmtiHeapReferenceKind _kind;
2563   bool _continue;
2564 
2565   jvmtiHeapReferenceKind root_kind()    { return _kind; }
2566 
2567  public:
2568   void set_kind(jvmtiHeapReferenceKind kind) {
2569     _kind = kind;
2570     _continue = true;
2571   }
2572 
2573   inline bool stopped() {
2574     return !_continue;
2575   }
2576 
2577   void do_oop(oop* obj_p) {
2578     // iteration has terminated
2579     if (stopped()) {
2580       return;
2581     }
2582 
2583     // ignore null or deleted handles
2584     oop o = *obj_p;
2585     if (o == NULL || o == JNIHandles::deleted_handle()) {
2586       return;
2587     }
2588 
2589     assert(Universe::heap()->is_in_reserved(o), "should be impossible");
2590 
2591     jvmtiHeapReferenceKind kind = root_kind();
2592     if (kind == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2593       // SystemDictionary::always_strong_oops_do reports the application
2594       // class loader as a root. We want this root to be reported as
2595       // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2596       if (!o->is_instance() || !InstanceKlass::cast(o->klass())->is_mirror_instance_klass()) {
2597         kind = JVMTI_HEAP_REFERENCE_OTHER;
2598       }
2599     }
2600 
2601     // some objects are ignored - in the case of simple
2602     // roots it's mostly Symbol*s that we are skipping
2603     // here.
2604     if (!ServiceUtil::visible_oop(o)) {
2605       return;
2606     }
2607 
2608     // invoke the callback
2609     _continue = CallbackInvoker::report_simple_root(kind, o);
2610 
2611   }
2612   virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2613 };
2614 
2615 // A supporting closure used to process JNI locals
2616 class JNILocalRootsClosure : public OopClosure {
2617  private:
2618   jlong _thread_tag;
2619   jlong _tid;
2620   jint _depth;
2621   jmethodID _method;
2622   bool _continue;
2623  public:
2624   void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2625     _thread_tag = thread_tag;
2626     _tid = tid;
2627     _depth = depth;
2628     _method = method;
2629     _continue = true;
2630   }
2631 
2632   inline bool stopped() {
2633     return !_continue;
2634   }
2635 
2636   void do_oop(oop* obj_p) {
2637     // iteration has terminated
2638     if (stopped()) {
2639       return;
2640     }
2641 
2642     // ignore null or deleted handles
2643     oop o = *obj_p;
2644     if (o == NULL || o == JNIHandles::deleted_handle()) {
2645       return;
2646     }
2647 
2648     if (!ServiceUtil::visible_oop(o)) {
2649       return;
2650     }
2651 
2652     // invoke the callback
2653     _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2654   }
2655   virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2656 };
2657 
2658 
2659 // A VM operation to iterate over objects that are reachable from
2660 // a set of roots or an initial object.
2661 //
2662 // For VM_HeapWalkOperation the set of roots used is :-
2663 //
2664 // - All JNI global references
2665 // - All inflated monitors
2666 // - All classes loaded by the boot class loader (or all classes
2667 //     in the event that class unloading is disabled)
2668 // - All java threads
2669 // - For each java thread then all locals and JNI local references
2670 //      on the thread's execution stack
2671 // - All visible/explainable objects from Universes::oops_do
2672 //
2673 class VM_HeapWalkOperation: public VM_Operation {
2674  private:
2675   enum {
2676     initial_visit_stack_size = 4000
2677   };
2678 
2679   bool _is_advanced_heap_walk;                      // indicates FollowReferences
2680   JvmtiTagMap* _tag_map;
2681   Handle _initial_object;
2682   GrowableArray<oop>* _visit_stack;                 // the visit stack
2683 
2684   bool _collecting_heap_roots;                      // are we collecting roots
2685   bool _following_object_refs;                      // are we following object references
2686 
2687   bool _reporting_primitive_fields;                 // optional reporting
2688   bool _reporting_primitive_array_values;
2689   bool _reporting_string_values;
2690 
2691   GrowableArray<oop>* create_visit_stack() {
2692     return new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(initial_visit_stack_size, true);
2693   }
2694 
2695   // accessors
2696   bool is_advanced_heap_walk() const               { return _is_advanced_heap_walk; }
2697   JvmtiTagMap* tag_map() const                     { return _tag_map; }
2698   Handle initial_object() const                    { return _initial_object; }
2699 
2700   bool is_following_references() const             { return _following_object_refs; }
2701 
2702   bool is_reporting_primitive_fields()  const      { return _reporting_primitive_fields; }
2703   bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2704   bool is_reporting_string_values() const          { return _reporting_string_values; }
2705 
2706   GrowableArray<oop>* visit_stack() const          { return _visit_stack; }
2707 
2708   // iterate over the various object types
2709   inline bool iterate_over_array(oop o);
2710   inline bool iterate_over_type_array(oop o);
2711   inline bool iterate_over_class(oop o);
2712   inline bool iterate_over_object(oop o);
2713 
2714   // root collection
2715   inline bool collect_simple_roots();
2716   inline bool collect_stack_roots();
2717   inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2718 
2719   // visit an object
2720   inline bool visit(oop o);
2721 
2722  public:
2723   VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2724                        Handle initial_object,
2725                        BasicHeapWalkContext callbacks,
2726                        const void* user_data);
2727 
2728   VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2729                        Handle initial_object,
2730                        AdvancedHeapWalkContext callbacks,
2731                        const void* user_data);
2732 
2733   ~VM_HeapWalkOperation();
2734 
2735   VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2736   void doit();
2737 };
2738 
2739 
2740 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2741                                            Handle initial_object,
2742                                            BasicHeapWalkContext callbacks,
2743                                            const void* user_data) {
2744   _is_advanced_heap_walk = false;
2745   _tag_map = tag_map;
2746   _initial_object = initial_object;
2747   _following_object_refs = (callbacks.object_ref_callback() != NULL);
2748   _reporting_primitive_fields = false;
2749   _reporting_primitive_array_values = false;
2750   _reporting_string_values = false;
2751   _visit_stack = create_visit_stack();
2752 
2753 
2754   CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2755 }
2756 
2757 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2758                                            Handle initial_object,
2759                                            AdvancedHeapWalkContext callbacks,
2760                                            const void* user_data) {
2761   _is_advanced_heap_walk = true;
2762   _tag_map = tag_map;
2763   _initial_object = initial_object;
2764   _following_object_refs = true;
2765   _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2766   _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2767   _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2768   _visit_stack = create_visit_stack();
2769 
2770   CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2771 }
2772 
2773 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2774   if (_following_object_refs) {
2775     assert(_visit_stack != NULL, "checking");
2776     delete _visit_stack;
2777     _visit_stack = NULL;
2778   }
2779 }
2780 
2781 // an array references its class and has a reference to
2782 // each element in the array
2783 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2784   objArrayOop array = objArrayOop(o);
2785 
2786   // array reference to its class
2787   oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
2788   if (!CallbackInvoker::report_class_reference(o, mirror)) {
2789     return false;
2790   }
2791 
2792   // iterate over the array and report each reference to a
2793   // non-null element
2794   for (int index=0; index<array->length(); index++) {
2795     oop elem = array->obj_at(index);
2796     if (elem == NULL) {
2797       continue;
2798     }
2799 
2800     // report the array reference o[index] = elem
2801     if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2802       return false;
2803     }
2804   }
2805   return true;
2806 }
2807 
2808 // a type array references its class
2809 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2810   Klass* k = o->klass();
2811   oop mirror = k->java_mirror();
2812   if (!CallbackInvoker::report_class_reference(o, mirror)) {
2813     return false;
2814   }
2815 
2816   // report the array contents if required
2817   if (is_reporting_primitive_array_values()) {
2818     if (!CallbackInvoker::report_primitive_array_values(o)) {
2819       return false;
2820     }
2821   }
2822   return true;
2823 }
2824 
2825 #ifdef ASSERT
2826 // verify that a static oop field is in range
2827 static inline bool verify_static_oop(InstanceKlass* ik,
2828                                      oop mirror, int offset) {
2829   address obj_p = (address)mirror + offset;
2830   address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2831   address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2832   assert(end >= start, "sanity check");
2833 
2834   if (obj_p >= start && obj_p < end) {
2835     return true;
2836   } else {
2837     return false;
2838   }
2839 }
2840 #endif // #ifdef ASSERT
2841 
2842 // a class references its super class, interfaces, class loader, ...
2843 // and finally its static fields
2844 inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) {
2845   int i;
2846   Klass* klass = java_lang_Class::as_Klass(java_class);
2847 
2848   if (klass->is_instance_klass()) {
2849     InstanceKlass* ik = InstanceKlass::cast(klass);
2850 
2851     // Ignore the class if it hasn't been initialized yet
2852     if (!ik->is_linked()) {
2853       return true;
2854     }
2855 
2856     // get the java mirror
2857     oop mirror = klass->java_mirror();
2858 
2859     // super (only if something more interesting than java.lang.Object)
2860     Klass* java_super = ik->java_super();
2861     if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2862       oop super = java_super->java_mirror();
2863       if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2864         return false;
2865       }
2866     }
2867 
2868     // class loader
2869     oop cl = ik->class_loader();
2870     if (cl != NULL) {
2871       if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2872         return false;
2873       }
2874     }
2875 
2876     // protection domain
2877     oop pd = ik->protection_domain();
2878     if (pd != NULL) {
2879       if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2880         return false;
2881       }
2882     }
2883 
2884     // signers
2885     oop signers = ik->signers();
2886     if (signers != NULL) {
2887       if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2888         return false;
2889       }
2890     }
2891 
2892     // references from the constant pool
2893     {
2894       ConstantPool* pool = ik->constants();
2895       for (int i = 1; i < pool->length(); i++) {
2896         constantTag tag = pool->tag_at(i).value();
2897         if (tag.is_string() || tag.is_klass()) {
2898           oop entry;
2899           if (tag.is_string()) {
2900             entry = pool->resolved_string_at(i);
2901             // If the entry is non-null it is resolved.
2902             if (entry == NULL) continue;
2903           } else {
2904             entry = pool->resolved_klass_at(i)->java_mirror();
2905           }
2906           if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2907             return false;
2908           }
2909         }
2910       }
2911     }
2912 
2913     // interfaces
2914     // (These will already have been reported as references from the constant pool
2915     //  but are specified by IterateOverReachableObjects and must be reported).
2916     Array<Klass*>* interfaces = ik->local_interfaces();
2917     for (i = 0; i < interfaces->length(); i++) {
2918       oop interf = ((Klass*)interfaces->at(i))->java_mirror();
2919       if (interf == NULL) {
2920         continue;
2921       }
2922       if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
2923         return false;
2924       }
2925     }
2926 
2927     // iterate over the static fields
2928 
2929     ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
2930     for (i=0; i<field_map->field_count(); i++) {
2931       ClassFieldDescriptor* field = field_map->field_at(i);
2932       char type = field->field_type();
2933       if (!is_primitive_field_type(type)) {
2934         oop fld_o = mirror->obj_field(field->field_offset());
2935         assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check");
2936         if (fld_o != NULL) {
2937           int slot = field->field_index();
2938           if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
2939             delete field_map;
2940             return false;
2941           }
2942         }
2943       } else {
2944          if (is_reporting_primitive_fields()) {
2945            address addr = (address)mirror + field->field_offset();
2946            int slot = field->field_index();
2947            if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
2948              delete field_map;
2949              return false;
2950           }
2951         }
2952       }
2953     }
2954     delete field_map;
2955 
2956     return true;
2957   }
2958 
2959   return true;
2960 }
2961 
2962 // an object references a class and its instance fields
2963 // (static fields are ignored here as we report these as
2964 // references from the class).
2965 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
2966   // reference to the class
2967   if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) {
2968     return false;
2969   }
2970 
2971   // iterate over instance fields
2972   ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
2973   for (int i=0; i<field_map->field_count(); i++) {
2974     ClassFieldDescriptor* field = field_map->field_at(i);
2975     char type = field->field_type();
2976     if (!is_primitive_field_type(type)) {
2977       oop fld_o = o->obj_field(field->field_offset());
2978       // ignore any objects that aren't visible to profiler
2979       if (fld_o != NULL && ServiceUtil::visible_oop(fld_o)) {
2980         assert(Universe::heap()->is_in_reserved(fld_o), "unsafe code should not "
2981                "have references to Klass* anymore");
2982         int slot = field->field_index();
2983         if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
2984           return false;
2985         }
2986       }
2987     } else {
2988       if (is_reporting_primitive_fields()) {
2989         // primitive instance field
2990         address addr = (address)o + field->field_offset();
2991         int slot = field->field_index();
2992         if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
2993           return false;
2994         }
2995       }
2996     }
2997   }
2998 
2999   // if the object is a java.lang.String
3000   if (is_reporting_string_values() &&
3001       o->klass() == SystemDictionary::String_klass()) {
3002     if (!CallbackInvoker::report_string_value(o)) {
3003       return false;
3004     }
3005   }
3006   return true;
3007 }
3008 
3009 
3010 // Collects all simple (non-stack) roots except for threads;
3011 // threads are handled in collect_stack_roots() as an optimization.
3012 // if there's a heap root callback provided then the callback is
3013 // invoked for each simple root.
3014 // if an object reference callback is provided then all simple
3015 // roots are pushed onto the marking stack so that they can be
3016 // processed later
3017 //
3018 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3019   SimpleRootsClosure blk;
3020 
3021   // JNI globals
3022   blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3023   JNIHandles::oops_do(&blk);
3024   if (blk.stopped()) {
3025     return false;
3026   }
3027 
3028   // Preloaded classes and loader from the system dictionary
3029   blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3030   SystemDictionary::always_strong_oops_do(&blk);
3031   ClassLoaderDataGraph::always_strong_oops_do(&blk, false);
3032   if (blk.stopped()) {
3033     return false;
3034   }
3035 
3036   // Inflated monitors
3037   blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3038   ObjectSynchronizer::oops_do(&blk);
3039   if (blk.stopped()) {
3040     return false;
3041   }
3042 
3043   // threads are now handled in collect_stack_roots()
3044 
3045   // Other kinds of roots maintained by HotSpot
3046   // Many of these won't be visible but others (such as instances of important
3047   // exceptions) will be visible.
3048   blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3049   Universe::oops_do(&blk);
3050 
3051   // If there are any non-perm roots in the code cache, visit them.
3052   blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3053   CodeBlobToOopClosure look_in_blobs(&blk, !CodeBlobToOopClosure::FixRelocations);
3054   CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3055 
3056   return true;
3057 }
3058 
3059 // Walk the stack of a given thread and find all references (locals
3060 // and JNI calls) and report these as stack references
3061 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3062                                                       JNILocalRootsClosure* blk)
3063 {
3064   oop threadObj = java_thread->threadObj();
3065   assert(threadObj != NULL, "sanity check");
3066 
3067   // only need to get the thread's tag once per thread
3068   jlong thread_tag = tag_for(_tag_map, threadObj);
3069 
3070   // also need the thread id
3071   jlong tid = java_lang_Thread::thread_id(threadObj);
3072 
3073 
3074   if (java_thread->has_last_Java_frame()) {
3075 
3076     // vframes are resource allocated
3077     Thread* current_thread = Thread::current();
3078     ResourceMark rm(current_thread);
3079     HandleMark hm(current_thread);
3080 
3081     RegisterMap reg_map(java_thread);
3082     frame f = java_thread->last_frame();
3083     vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
3084 
3085     bool is_top_frame = true;
3086     int depth = 0;
3087     frame* last_entry_frame = NULL;
3088 
3089     while (vf != NULL) {
3090       if (vf->is_java_frame()) {
3091 
3092         // java frame (interpreted, compiled, ...)
3093         javaVFrame *jvf = javaVFrame::cast(vf);
3094 
3095         // the jmethodID
3096         jmethodID method = jvf->method()->jmethod_id();
3097 
3098         if (!(jvf->method()->is_native())) {
3099           jlocation bci = (jlocation)jvf->bci();
3100           StackValueCollection* locals = jvf->locals();
3101           for (int slot=0; slot<locals->size(); slot++) {
3102             if (locals->at(slot)->type() == T_OBJECT) {
3103               oop o = locals->obj_at(slot)();
3104               if (o == NULL) {
3105                 continue;
3106               }
3107 
3108               // stack reference
3109               if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3110                                                    bci, slot, o)) {
3111                 return false;
3112               }
3113             }
3114           }
3115 
3116           StackValueCollection* exprs = jvf->expressions();
3117           for (int index=0; index < exprs->size(); index++) {
3118             if (exprs->at(index)->type() == T_OBJECT) {
3119               oop o = exprs->obj_at(index)();
3120               if (o == NULL) {
3121                 continue;
3122               }
3123 
3124               // stack reference
3125               if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3126                                                    bci, locals->size() + index, o)) {
3127                 return false;
3128               }
3129             }
3130           }
3131 
3132           // Follow oops from compiled nmethod
3133           if (jvf->cb() != NULL && jvf->cb()->is_nmethod()) {
3134             blk->set_context(thread_tag, tid, depth, method);
3135             jvf->cb()->as_nmethod()->oops_do(blk);
3136           }
3137         } else {
3138           blk->set_context(thread_tag, tid, depth, method);
3139           if (is_top_frame) {
3140             // JNI locals for the top frame.
3141             java_thread->active_handles()->oops_do(blk);
3142           } else {
3143             if (last_entry_frame != NULL) {
3144               // JNI locals for the entry frame
3145               assert(last_entry_frame->is_entry_frame(), "checking");
3146               last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3147             }
3148           }
3149         }
3150         last_entry_frame = NULL;
3151         depth++;
3152       } else {
3153         // externalVFrame - for an entry frame then we report the JNI locals
3154         // when we find the corresponding javaVFrame
3155         frame* fr = vf->frame_pointer();
3156         assert(fr != NULL, "sanity check");
3157         if (fr->is_entry_frame()) {
3158           last_entry_frame = fr;
3159         }
3160       }
3161 
3162       vf = vf->sender();
3163       is_top_frame = false;
3164     }
3165   } else {
3166     // no last java frame but there may be JNI locals
3167     blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3168     java_thread->active_handles()->oops_do(blk);
3169   }
3170   return true;
3171 }
3172 
3173 
3174 // Collects the simple roots for all threads and collects all
3175 // stack roots - for each thread it walks the execution
3176 // stack to find all references and local JNI refs.
3177 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3178   JNILocalRootsClosure blk;
3179   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
3180     oop threadObj = thread->threadObj();
3181     if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3182       // Collect the simple root for this thread before we
3183       // collect its stack roots
3184       if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD,
3185                                                threadObj)) {
3186         return false;
3187       }
3188       if (!collect_stack_roots(thread, &blk)) {
3189         return false;
3190       }
3191     }
3192   }
3193   return true;
3194 }
3195 
3196 // visit an object
3197 // first mark the object as visited
3198 // second get all the outbound references from this object (in other words, all
3199 // the objects referenced by this object).
3200 //
3201 bool VM_HeapWalkOperation::visit(oop o) {
3202   // mark object as visited
3203   assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3204   ObjectMarker::mark(o);
3205 
3206   // instance
3207   if (o->is_instance()) {
3208     if (o->klass() == SystemDictionary::Class_klass()) {
3209       if (!java_lang_Class::is_primitive(o)) {
3210         // a java.lang.Class
3211         return iterate_over_class(o);
3212       }
3213     } else {
3214       return iterate_over_object(o);
3215     }
3216   }
3217 
3218   // object array
3219   if (o->is_objArray()) {
3220     return iterate_over_array(o);
3221   }
3222 
3223   // type array
3224   if (o->is_typeArray()) {
3225     return iterate_over_type_array(o);
3226   }
3227 
3228   return true;
3229 }
3230 
3231 void VM_HeapWalkOperation::doit() {
3232   ResourceMark rm;
3233   ObjectMarkerController marker;
3234   ClassFieldMapCacheMark cm;
3235 
3236   assert(visit_stack()->is_empty(), "visit stack must be empty");
3237 
3238   // the heap walk starts with an initial object or the heap roots
3239   if (initial_object().is_null()) {
3240     // If either collect_stack_roots() or collect_simple_roots()
3241     // returns false at this point, then there are no mark bits
3242     // to reset.
3243     ObjectMarker::set_needs_reset(false);
3244 
3245     // Calling collect_stack_roots() before collect_simple_roots()
3246     // can result in a big performance boost for an agent that is
3247     // focused on analyzing references in the thread stacks.
3248     if (!collect_stack_roots()) return;
3249 
3250     if (!collect_simple_roots()) return;
3251 
3252     // no early return so enable heap traversal to reset the mark bits
3253     ObjectMarker::set_needs_reset(true);
3254   } else {
3255     visit_stack()->push(initial_object()());
3256   }
3257 
3258   // object references required
3259   if (is_following_references()) {
3260 
3261     // visit each object until all reachable objects have been
3262     // visited or the callback asked to terminate the iteration.
3263     while (!visit_stack()->is_empty()) {
3264       oop o = visit_stack()->pop();
3265       if (!ObjectMarker::visited(o)) {
3266         if (!visit(o)) {
3267           break;
3268         }
3269       }
3270     }
3271   }
3272 }
3273 
3274 // iterate over all objects that are reachable from a set of roots
3275 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3276                                                  jvmtiStackReferenceCallback stack_ref_callback,
3277                                                  jvmtiObjectReferenceCallback object_ref_callback,
3278                                                  const void* user_data) {
3279   MutexLocker ml(Heap_lock);
3280   BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3281   VM_HeapWalkOperation op(this, Handle(), context, user_data);
3282   VMThread::execute(&op);
3283 }
3284 
3285 // iterate over all objects that are reachable from a given object
3286 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3287                                                              jvmtiObjectReferenceCallback object_ref_callback,
3288                                                              const void* user_data) {
3289   oop obj = JNIHandles::resolve(object);
3290   Handle initial_object(Thread::current(), obj);
3291 
3292   MutexLocker ml(Heap_lock);
3293   BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3294   VM_HeapWalkOperation op(this, initial_object, context, user_data);
3295   VMThread::execute(&op);
3296 }
3297 
3298 // follow references from an initial object or the GC roots
3299 void JvmtiTagMap::follow_references(jint heap_filter,
3300                                     Klass* klass,
3301                                     jobject object,
3302                                     const jvmtiHeapCallbacks* callbacks,
3303                                     const void* user_data)
3304 {
3305   oop obj = JNIHandles::resolve(object);
3306   Handle initial_object(Thread::current(), obj);
3307 
3308   MutexLocker ml(Heap_lock);
3309   AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3310   VM_HeapWalkOperation op(this, initial_object, context, user_data);
3311   VMThread::execute(&op);
3312 }
3313 
3314 
3315 void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
3316   // No locks during VM bring-up (0 threads) and no safepoints after main
3317   // thread creation and before VMThread creation (1 thread); initial GC
3318   // verification can happen in that window which gets to here.
3319   assert(Threads::number_of_threads() <= 1 ||
3320          SafepointSynchronize::is_at_safepoint(),
3321          "must be executed at a safepoint");
3322   if (JvmtiEnv::environments_might_exist()) {
3323     JvmtiEnvIterator it;
3324     for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3325       JvmtiTagMap* tag_map = env->tag_map();
3326       if (tag_map != NULL && !tag_map->is_empty()) {
3327         tag_map->do_weak_oops(is_alive, f);
3328       }
3329     }
3330   }
3331 }
3332 
3333 void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
3334 
3335   // does this environment have the OBJECT_FREE event enabled
3336   bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3337 
3338   // counters used for trace message
3339   int freed = 0;
3340   int moved = 0;
3341 
3342   JvmtiTagHashmap* hashmap = this->hashmap();
3343 
3344   // reenable sizing (if disabled)
3345   hashmap->set_resizing_enabled(true);
3346 
3347   // if the hashmap is empty then we can skip it
3348   if (hashmap->_entry_count == 0) {
3349     return;
3350   }
3351 
3352   // now iterate through each entry in the table
3353 
3354   JvmtiTagHashmapEntry** table = hashmap->table();
3355   int size = hashmap->size();
3356 
3357   JvmtiTagHashmapEntry* delayed_add = NULL;
3358 
3359   for (int pos = 0; pos < size; ++pos) {
3360     JvmtiTagHashmapEntry* entry = table[pos];
3361     JvmtiTagHashmapEntry* prev = NULL;
3362 
3363     while (entry != NULL) {
3364       JvmtiTagHashmapEntry* next = entry->next();
3365 
3366       oop* obj = entry->object_addr();
3367 
3368       // has object been GC'ed
3369       if (!is_alive->do_object_b(entry->object())) {
3370         // grab the tag
3371         jlong tag = entry->tag();
3372         guarantee(tag != 0, "checking");
3373 
3374         // remove GC'ed entry from hashmap and return the
3375         // entry to the free list
3376         hashmap->remove(prev, pos, entry);
3377         destroy_entry(entry);
3378 
3379         // post the event to the profiler
3380         if (post_object_free) {
3381           JvmtiExport::post_object_free(env(), tag);
3382         }
3383 
3384         ++freed;
3385       } else {
3386         f->do_oop(entry->object_addr());
3387         oop new_oop = entry->object();
3388 
3389         // if the object has moved then re-hash it and move its
3390         // entry to its new location.
3391         unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
3392         if (new_pos != (unsigned int)pos) {
3393           if (prev == NULL) {
3394             table[pos] = next;
3395           } else {
3396             prev->set_next(next);
3397           }
3398           if (new_pos < (unsigned int)pos) {
3399             entry->set_next(table[new_pos]);
3400             table[new_pos] = entry;
3401           } else {
3402             // Delay adding this entry to it's new position as we'd end up
3403             // hitting it again during this iteration.
3404             entry->set_next(delayed_add);
3405             delayed_add = entry;
3406           }
3407           moved++;
3408         } else {
3409           // object didn't move
3410           prev = entry;
3411         }
3412       }
3413 
3414       entry = next;
3415     }
3416   }
3417 
3418   // Re-add all the entries which were kept aside
3419   while (delayed_add != NULL) {
3420     JvmtiTagHashmapEntry* next = delayed_add->next();
3421     unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
3422     delayed_add->set_next(table[pos]);
3423     table[pos] = delayed_add;
3424     delayed_add = next;
3425   }
3426 
3427   log_debug(jvmti, objecttagging)("(%d->%d, %d freed, %d total moves)",
3428                                   hashmap->_entry_count + freed, hashmap->_entry_count, freed, moved);
3429 }