1 /*
   2  * Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "classfile/vmSymbols.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "jvmtifiles/jvmtiEnv.hpp"
  31 #include "oops/instanceMirrorKlass.hpp"
  32 #include "oops/objArrayKlass.hpp"
  33 #include "oops/objArrayOop.inline.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "prims/jvmtiEventController.hpp"
  36 #include "prims/jvmtiEventController.inline.hpp"
  37 #include "prims/jvmtiExport.hpp"
  38 #include "prims/jvmtiImpl.hpp"
  39 #include "prims/jvmtiTagMap.hpp"
  40 #include "runtime/biasedLocking.hpp"
  41 #include "runtime/javaCalls.hpp"
  42 #include "runtime/jniHandles.hpp"
  43 #include "runtime/mutex.hpp"
  44 #include "runtime/mutexLocker.hpp"
  45 #include "runtime/reflectionUtils.hpp"
  46 #include "runtime/vframe.hpp"
  47 #include "runtime/vmThread.hpp"
  48 #include "runtime/vm_operations.hpp"
  49 #include "services/serviceUtil.hpp"
  50 #include "utilities/macros.hpp"
  51 #if INCLUDE_ALL_GCS
  52 #include "gc/parallel/parallelScavengeHeap.hpp"
  53 #endif // INCLUDE_ALL_GCS
  54 
  55 // JvmtiTagHashmapEntry
  56 //
  57 // Each entry encapsulates a reference to the tagged object
  58 // and the tag value. In addition an entry includes a next pointer which
  59 // is used to chain entries together.
  60 
  61 class JvmtiTagHashmapEntry : public CHeapObj<mtInternal> {
  62  private:
  63   friend class JvmtiTagMap;
  64 
  65   oop _object;                          // tagged object
  66   jlong _tag;                           // the tag
  67   JvmtiTagHashmapEntry* _next;          // next on the list
  68 
  69   inline void init(oop object, jlong tag) {
  70     _object = object;
  71     _tag = tag;
  72     _next = NULL;
  73   }
  74 
  75   // constructor
  76   JvmtiTagHashmapEntry(oop object, jlong tag)         { init(object, tag); }
  77 
  78  public:
  79 
  80   // accessor methods
  81   inline oop object() const                           { return _object; }
  82   inline oop* object_addr()                           { return &_object; }
  83   inline jlong tag() const                            { return _tag; }
  84 
  85   inline void set_tag(jlong tag) {
  86     assert(tag != 0, "can't be zero");
  87     _tag = tag;
  88   }
  89 
  90   inline JvmtiTagHashmapEntry* next() const             { return _next; }
  91   inline void set_next(JvmtiTagHashmapEntry* next)      { _next = next; }
  92 };
  93 
  94 
  95 // JvmtiTagHashmap
  96 //
  97 // A hashmap is essentially a table of pointers to entries. Entries
  98 // are hashed to a location, or position in the table, and then
  99 // chained from that location. The "key" for hashing is address of
 100 // the object, or oop. The "value" is the tag value.
 101 //
 102 // A hashmap maintains a count of the number entries in the hashmap
 103 // and resizes if the number of entries exceeds a given threshold.
 104 // The threshold is specified as a percentage of the size - for
 105 // example a threshold of 0.75 will trigger the hashmap to resize
 106 // if the number of entries is >75% of table size.
 107 //
 108 // A hashmap provides functions for adding, removing, and finding
 109 // entries. It also provides a function to iterate over all entries
 110 // in the hashmap.
 111 
 112 class JvmtiTagHashmap : public CHeapObj<mtInternal> {
 113  private:
 114   friend class JvmtiTagMap;
 115 
 116   enum {
 117     small_trace_threshold  = 10000,                  // threshold for tracing
 118     medium_trace_threshold = 100000,
 119     large_trace_threshold  = 1000000,
 120     initial_trace_threshold = small_trace_threshold
 121   };
 122 
 123   static int _sizes[];                  // array of possible hashmap sizes
 124   int _size;                            // actual size of the table
 125   int _size_index;                      // index into size table
 126 
 127   int _entry_count;                     // number of entries in the hashmap
 128 
 129   float _load_factor;                   // load factor as a % of the size
 130   int _resize_threshold;                // computed threshold to trigger resizing.
 131   bool _resizing_enabled;               // indicates if hashmap can resize
 132 
 133   int _trace_threshold;                 // threshold for trace messages
 134 
 135   JvmtiTagHashmapEntry** _table;        // the table of entries.
 136 
 137   // private accessors
 138   int resize_threshold() const                  { return _resize_threshold; }
 139   int trace_threshold() const                   { return _trace_threshold; }
 140 
 141   // initialize the hashmap
 142   void init(int size_index=0, float load_factor=4.0f) {
 143     int initial_size =  _sizes[size_index];
 144     _size_index = size_index;
 145     _size = initial_size;
 146     _entry_count = 0;
 147     if (TraceJVMTIObjectTagging) {
 148       _trace_threshold = initial_trace_threshold;
 149     } else {
 150       _trace_threshold = -1;
 151     }
 152     _load_factor = load_factor;
 153     _resize_threshold = (int)(_load_factor * _size);
 154     _resizing_enabled = true;
 155     size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
 156     _table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
 157     if (_table == NULL) {
 158       vm_exit_out_of_memory(s, OOM_MALLOC_ERROR,
 159         "unable to allocate initial hashtable for jvmti object tags");
 160     }
 161     for (int i=0; i<initial_size; i++) {
 162       _table[i] = NULL;
 163     }
 164   }
 165 
 166   // hash a given key (oop) with the specified size
 167   static unsigned int hash(oop key, int size) {
 168     // shift right to get better distribution (as these bits will be zero
 169     // with aligned addresses)
 170     unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key));
 171 #ifdef _LP64
 172     return (addr >> 3) % size;
 173 #else
 174     return (addr >> 2) % size;
 175 #endif
 176   }
 177 
 178   // hash a given key (oop)
 179   unsigned int hash(oop key) {
 180     return hash(key, _size);
 181   }
 182 
 183   // resize the hashmap - allocates a large table and re-hashes
 184   // all entries into the new table.
 185   void resize() {
 186     int new_size_index = _size_index+1;
 187     int new_size = _sizes[new_size_index];
 188     if (new_size < 0) {
 189       // hashmap already at maximum capacity
 190       return;
 191     }
 192 
 193     // allocate new table
 194     size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
 195     JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
 196     if (new_table == NULL) {
 197       warning("unable to allocate larger hashtable for jvmti object tags");
 198       set_resizing_enabled(false);
 199       return;
 200     }
 201 
 202     // initialize new table
 203     int i;
 204     for (i=0; i<new_size; i++) {
 205       new_table[i] = NULL;
 206     }
 207 
 208     // rehash all entries into the new table
 209     for (i=0; i<_size; i++) {
 210       JvmtiTagHashmapEntry* entry = _table[i];
 211       while (entry != NULL) {
 212         JvmtiTagHashmapEntry* next = entry->next();
 213         oop key = entry->object();
 214         assert(key != NULL, "jni weak reference cleared!!");
 215         unsigned int h = hash(key, new_size);
 216         JvmtiTagHashmapEntry* anchor = new_table[h];
 217         if (anchor == NULL) {
 218           new_table[h] = entry;
 219           entry->set_next(NULL);
 220         } else {
 221           entry->set_next(anchor);
 222           new_table[h] = entry;
 223         }
 224         entry = next;
 225       }
 226     }
 227 
 228     // free old table and update settings.
 229     os::free((void*)_table);
 230     _table = new_table;
 231     _size_index = new_size_index;
 232     _size = new_size;
 233 
 234     // compute new resize threshold
 235     _resize_threshold = (int)(_load_factor * _size);
 236   }
 237 
 238 
 239   // internal remove function - remove an entry at a given position in the
 240   // table.
 241   inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
 242     assert(pos >= 0 && pos < _size, "out of range");
 243     if (prev == NULL) {
 244       _table[pos] = entry->next();
 245     } else {
 246       prev->set_next(entry->next());
 247     }
 248     assert(_entry_count > 0, "checking");
 249     _entry_count--;
 250   }
 251 
 252   // resizing switch
 253   bool is_resizing_enabled() const          { return _resizing_enabled; }
 254   void set_resizing_enabled(bool enable)    { _resizing_enabled = enable; }
 255 
 256   // debugging
 257   void print_memory_usage();
 258   void compute_next_trace_threshold();
 259 
 260  public:
 261 
 262   // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
 263   // The preferred size is rounded down to an actual size.
 264   JvmtiTagHashmap(int size, float load_factor=0.0f) {
 265     int i=0;
 266     while (_sizes[i] < size) {
 267       if (_sizes[i] < 0) {
 268         assert(i > 0, "sanity check");
 269         i--;
 270         break;
 271       }
 272       i++;
 273     }
 274 
 275     // if a load factor is specified then use it, otherwise use default
 276     if (load_factor > 0.01f) {
 277       init(i, load_factor);
 278     } else {
 279       init(i);
 280     }
 281   }
 282 
 283   // create a JvmtiTagHashmap with default settings
 284   JvmtiTagHashmap() {
 285     init();
 286   }
 287 
 288   // release table when JvmtiTagHashmap destroyed
 289   ~JvmtiTagHashmap() {
 290     if (_table != NULL) {
 291       os::free((void*)_table);
 292       _table = NULL;
 293     }
 294   }
 295 
 296   // accessors
 297   int size() const                              { return _size; }
 298   JvmtiTagHashmapEntry** table() const          { return _table; }
 299   int entry_count() const                       { return _entry_count; }
 300 
 301   // find an entry in the hashmap, returns NULL if not found.
 302   inline JvmtiTagHashmapEntry* find(oop key) {
 303     unsigned int h = hash(key);
 304     JvmtiTagHashmapEntry* entry = _table[h];
 305     while (entry != NULL) {
 306       if (entry->object() == key) {
 307          return entry;
 308       }
 309       entry = entry->next();
 310     }
 311     return NULL;
 312   }
 313 
 314 
 315   // add a new entry to hashmap
 316   inline void add(oop key, JvmtiTagHashmapEntry* entry) {
 317     assert(key != NULL, "checking");
 318     assert(find(key) == NULL, "duplicate detected");
 319     unsigned int h = hash(key);
 320     JvmtiTagHashmapEntry* anchor = _table[h];
 321     if (anchor == NULL) {
 322       _table[h] = entry;
 323       entry->set_next(NULL);
 324     } else {
 325       entry->set_next(anchor);
 326       _table[h] = entry;
 327     }
 328 
 329     _entry_count++;
 330     if (trace_threshold() > 0 && entry_count() >= trace_threshold()) {
 331       assert(TraceJVMTIObjectTagging, "should only get here when tracing");
 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   if (trace_threshold() < medium_trace_threshold) {
 411     _trace_threshold += small_trace_threshold;
 412   } else {
 413     if (trace_threshold() < large_trace_threshold) {
 414       _trace_threshold += medium_trace_threshold;
 415     } else {
 416       _trace_threshold += large_trace_threshold;
 417     }
 418   }
 419 }
 420 
 421 // create a JvmtiTagMap
 422 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
 423   _env(env),
 424   _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
 425   _free_entries(NULL),
 426   _free_entries_count(0)
 427 {
 428   assert(JvmtiThreadState_lock->is_locked(), "sanity check");
 429   assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
 430 
 431   _hashmap = new JvmtiTagHashmap();
 432 
 433   // finally add us to the environment
 434   ((JvmtiEnvBase *)env)->set_tag_map(this);
 435 }
 436 
 437 
 438 // destroy a JvmtiTagMap
 439 JvmtiTagMap::~JvmtiTagMap() {
 440 
 441   // no lock acquired as we assume the enclosing environment is
 442   // also being destroryed.
 443   ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
 444 
 445   JvmtiTagHashmapEntry** table = _hashmap->table();
 446   for (int j = 0; j < _hashmap->size(); j++) {
 447     JvmtiTagHashmapEntry* entry = table[j];
 448     while (entry != NULL) {
 449       JvmtiTagHashmapEntry* next = entry->next();
 450       delete entry;
 451       entry = next;
 452     }
 453   }
 454 
 455   // finally destroy the hashmap
 456   delete _hashmap;
 457   _hashmap = NULL;
 458 
 459   // remove any entries on the free list
 460   JvmtiTagHashmapEntry* entry = _free_entries;
 461   while (entry != NULL) {
 462     JvmtiTagHashmapEntry* next = entry->next();
 463     delete entry;
 464     entry = next;
 465   }
 466   _free_entries = NULL;
 467 }
 468 
 469 // create a hashmap entry
 470 // - if there's an entry on the (per-environment) free list then this
 471 // is returned. Otherwise an new entry is allocated.
 472 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
 473   assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
 474   JvmtiTagHashmapEntry* entry;
 475   if (_free_entries == NULL) {
 476     entry = new JvmtiTagHashmapEntry(ref, tag);
 477   } else {
 478     assert(_free_entries_count > 0, "mismatched _free_entries_count");
 479     _free_entries_count--;
 480     entry = _free_entries;
 481     _free_entries = entry->next();
 482     entry->init(ref, tag);
 483   }
 484   return entry;
 485 }
 486 
 487 // destroy an entry by returning it to the free list
 488 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
 489   assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
 490   // limit the size of the free list
 491   if (_free_entries_count >= max_free_entries) {
 492     delete entry;
 493   } else {
 494     entry->set_next(_free_entries);
 495     _free_entries = entry;
 496     _free_entries_count++;
 497   }
 498 }
 499 
 500 // returns the tag map for the given environments. If the tag map
 501 // doesn't exist then it is created.
 502 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
 503   JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
 504   if (tag_map == NULL) {
 505     MutexLocker mu(JvmtiThreadState_lock);
 506     tag_map = ((JvmtiEnvBase*)env)->tag_map();
 507     if (tag_map == NULL) {
 508       tag_map = new JvmtiTagMap(env);
 509     }
 510   } else {
 511     CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
 512   }
 513   return tag_map;
 514 }
 515 
 516 // iterate over all entries in the tag map.
 517 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
 518   hashmap()->entry_iterate(closure);
 519 }
 520 
 521 // returns true if the hashmaps are empty
 522 bool JvmtiTagMap::is_empty() {
 523   assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
 524   return hashmap()->entry_count() == 0;
 525 }
 526 
 527 
 528 // Return the tag value for an object, or 0 if the object is
 529 // not tagged
 530 //
 531 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
 532   JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
 533   if (entry == NULL) {
 534     return 0;
 535   } else {
 536     return entry->tag();
 537   }
 538 }
 539 
 540 
 541 // A CallbackWrapper is a support class for querying and tagging an object
 542 // around a callback to a profiler. The constructor does pre-callback
 543 // work to get the tag value, klass tag value, ... and the destructor
 544 // does the post-callback work of tagging or untagging the object.
 545 //
 546 // {
 547 //   CallbackWrapper wrapper(tag_map, o);
 548 //
 549 //   (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
 550 //
 551 // } // wrapper goes out of scope here which results in the destructor
 552 //      checking to see if the object has been tagged, untagged, or the
 553 //      tag value has changed.
 554 //
 555 class CallbackWrapper : public StackObj {
 556  private:
 557   JvmtiTagMap* _tag_map;
 558   JvmtiTagHashmap* _hashmap;
 559   JvmtiTagHashmapEntry* _entry;
 560   oop _o;
 561   jlong _obj_size;
 562   jlong _obj_tag;
 563   jlong _klass_tag;
 564 
 565  protected:
 566   JvmtiTagMap* tag_map() const      { return _tag_map; }
 567 
 568   // invoked post-callback to tag, untag, or update the tag of an object
 569   void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
 570                                        JvmtiTagHashmapEntry* entry, jlong obj_tag);
 571  public:
 572   CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
 573     assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
 574            "MT unsafe or must be VM thread");
 575 
 576     // object to tag
 577     _o = o;
 578 
 579     // object size
 580     _obj_size = (jlong)_o->size() * wordSize;
 581 
 582     // record the context
 583     _tag_map = tag_map;
 584     _hashmap = tag_map->hashmap();
 585     _entry = _hashmap->find(_o);
 586 
 587     // get object tag
 588     _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
 589 
 590     // get the class and the class's tag value
 591     assert(InstanceKlass::cast(SystemDictionary::Class_klass())->is_mirror_instance_klass(), "Is not?");
 592 
 593     _klass_tag = tag_for(tag_map, _o->klass()->java_mirror());
 594   }
 595 
 596   ~CallbackWrapper() {
 597     post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
 598   }
 599 
 600   inline jlong* obj_tag_p()                     { return &_obj_tag; }
 601   inline jlong obj_size() const                 { return _obj_size; }
 602   inline jlong obj_tag() const                  { return _obj_tag; }
 603   inline jlong klass_tag() const                { return _klass_tag; }
 604 };
 605 
 606 
 607 
 608 // callback post-callback to tag, untag, or update the tag of an object
 609 void inline CallbackWrapper::post_callback_tag_update(oop o,
 610                                                       JvmtiTagHashmap* hashmap,
 611                                                       JvmtiTagHashmapEntry* entry,
 612                                                       jlong obj_tag) {
 613   if (entry == NULL) {
 614     if (obj_tag != 0) {
 615       // callback has tagged the object
 616       assert(Thread::current()->is_VM_thread(), "must be VMThread");
 617       entry = tag_map()->create_entry(o, obj_tag);
 618       hashmap->add(o, entry);
 619     }
 620   } else {
 621     // object was previously tagged - the callback may have untagged
 622     // the object or changed the tag value
 623     if (obj_tag == 0) {
 624 
 625       JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
 626       assert(entry_removed == entry, "checking");
 627       tag_map()->destroy_entry(entry);
 628 
 629     } else {
 630       if (obj_tag != entry->tag()) {
 631          entry->set_tag(obj_tag);
 632       }
 633     }
 634   }
 635 }
 636 
 637 // An extended CallbackWrapper used when reporting an object reference
 638 // to the agent.
 639 //
 640 // {
 641 //   TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
 642 //
 643 //   (*callback)(wrapper.klass_tag(),
 644 //               wrapper.obj_size(),
 645 //               wrapper.obj_tag_p()
 646 //               wrapper.referrer_tag_p(), ...)
 647 //
 648 // } // wrapper goes out of scope here which results in the destructor
 649 //      checking to see if the referrer object has been tagged, untagged,
 650 //      or the tag value has changed.
 651 //
 652 class TwoOopCallbackWrapper : public CallbackWrapper {
 653  private:
 654   bool _is_reference_to_self;
 655   JvmtiTagHashmap* _referrer_hashmap;
 656   JvmtiTagHashmapEntry* _referrer_entry;
 657   oop _referrer;
 658   jlong _referrer_obj_tag;
 659   jlong _referrer_klass_tag;
 660   jlong* _referrer_tag_p;
 661 
 662   bool is_reference_to_self() const             { return _is_reference_to_self; }
 663 
 664  public:
 665   TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
 666     CallbackWrapper(tag_map, o)
 667   {
 668     // self reference needs to be handled in a special way
 669     _is_reference_to_self = (referrer == o);
 670 
 671     if (_is_reference_to_self) {
 672       _referrer_klass_tag = klass_tag();
 673       _referrer_tag_p = obj_tag_p();
 674     } else {
 675       _referrer = referrer;
 676       // record the context
 677       _referrer_hashmap = tag_map->hashmap();
 678       _referrer_entry = _referrer_hashmap->find(_referrer);
 679 
 680       // get object tag
 681       _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
 682       _referrer_tag_p = &_referrer_obj_tag;
 683 
 684       // get referrer class tag.
 685       _referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror());
 686     }
 687   }
 688 
 689   ~TwoOopCallbackWrapper() {
 690     if (!is_reference_to_self()){
 691       post_callback_tag_update(_referrer,
 692                                _referrer_hashmap,
 693                                _referrer_entry,
 694                                _referrer_obj_tag);
 695     }
 696   }
 697 
 698   // address of referrer tag
 699   // (for a self reference this will return the same thing as obj_tag_p())
 700   inline jlong* referrer_tag_p()        { return _referrer_tag_p; }
 701 
 702   // referrer's class tag
 703   inline jlong referrer_klass_tag()     { return _referrer_klass_tag; }
 704 };
 705 
 706 // tag an object
 707 //
 708 // This function is performance critical. If many threads attempt to tag objects
 709 // around the same time then it's possible that the Mutex associated with the
 710 // tag map will be a hot lock.
 711 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
 712   MutexLocker ml(lock());
 713 
 714   // resolve the object
 715   oop o = JNIHandles::resolve_non_null(object);
 716 
 717   // see if the object is already tagged
 718   JvmtiTagHashmap* hashmap = _hashmap;
 719   JvmtiTagHashmapEntry* entry = hashmap->find(o);
 720 
 721   // if the object is not already tagged then we tag it
 722   if (entry == NULL) {
 723     if (tag != 0) {
 724       entry = create_entry(o, tag);
 725       hashmap->add(o, entry);
 726     } else {
 727       // no-op
 728     }
 729   } else {
 730     // if the object is already tagged then we either update
 731     // the tag (if a new tag value has been provided)
 732     // or remove the object if the new tag value is 0.
 733     if (tag == 0) {
 734       hashmap->remove(o);
 735       destroy_entry(entry);
 736     } else {
 737       entry->set_tag(tag);
 738     }
 739   }
 740 }
 741 
 742 // get the tag for an object
 743 jlong JvmtiTagMap::get_tag(jobject object) {
 744   MutexLocker ml(lock());
 745 
 746   // resolve the object
 747   oop o = JNIHandles::resolve_non_null(object);
 748 
 749   return tag_for(this, o);
 750 }
 751 
 752 
 753 // Helper class used to describe the static or instance fields of a class.
 754 // For each field it holds the field index (as defined by the JVMTI specification),
 755 // the field type, and the offset.
 756 
 757 class ClassFieldDescriptor: public CHeapObj<mtInternal> {
 758  private:
 759   int _field_index;
 760   int _field_offset;
 761   char _field_type;
 762  public:
 763   ClassFieldDescriptor(int index, char type, int offset) :
 764     _field_index(index), _field_type(type), _field_offset(offset) {
 765   }
 766   int field_index()  const  { return _field_index; }
 767   char field_type()  const  { return _field_type; }
 768   int field_offset() const  { return _field_offset; }
 769 };
 770 
 771 class ClassFieldMap: public CHeapObj<mtInternal> {
 772  private:
 773   enum {
 774     initial_field_count = 5
 775   };
 776 
 777   // list of field descriptors
 778   GrowableArray<ClassFieldDescriptor*>* _fields;
 779 
 780   // constructor
 781   ClassFieldMap();
 782 
 783   // add a field
 784   void add(int index, char type, int offset);
 785 
 786   // returns the field count for the given class
 787   static int compute_field_count(instanceKlassHandle ikh);
 788 
 789  public:
 790   ~ClassFieldMap();
 791 
 792   // access
 793   int field_count()                     { return _fields->length(); }
 794   ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
 795 
 796   // functions to create maps of static or instance fields
 797   static ClassFieldMap* create_map_of_static_fields(Klass* k);
 798   static ClassFieldMap* create_map_of_instance_fields(oop obj);
 799 };
 800 
 801 ClassFieldMap::ClassFieldMap() {
 802   _fields = new (ResourceObj::C_HEAP, mtInternal)
 803     GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
 804 }
 805 
 806 ClassFieldMap::~ClassFieldMap() {
 807   for (int i=0; i<_fields->length(); i++) {
 808     delete _fields->at(i);
 809   }
 810   delete _fields;
 811 }
 812 
 813 void ClassFieldMap::add(int index, char type, int offset) {
 814   ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
 815   _fields->append(field);
 816 }
 817 
 818 // Returns a heap allocated ClassFieldMap to describe the static fields
 819 // of the given class.
 820 //
 821 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
 822   HandleMark hm;
 823   instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
 824 
 825   // create the field map
 826   ClassFieldMap* field_map = new ClassFieldMap();
 827 
 828   FilteredFieldStream f(ikh, false, false);
 829   int max_field_index = f.field_count()-1;
 830 
 831   int index = 0;
 832   for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
 833     // ignore instance fields
 834     if (!fld.access_flags().is_static()) {
 835       continue;
 836     }
 837     field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
 838   }
 839   return field_map;
 840 }
 841 
 842 // Returns a heap allocated ClassFieldMap to describe the instance fields
 843 // of the given class. All instance fields are included (this means public
 844 // and private fields declared in superclasses and superinterfaces too).
 845 //
 846 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
 847   HandleMark hm;
 848   instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
 849 
 850   // create the field map
 851   ClassFieldMap* field_map = new ClassFieldMap();
 852 
 853   FilteredFieldStream f(ikh, false, false);
 854 
 855   int max_field_index = f.field_count()-1;
 856 
 857   int index = 0;
 858   for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
 859     // ignore static fields
 860     if (fld.access_flags().is_static()) {
 861       continue;
 862     }
 863     field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
 864   }
 865 
 866   return field_map;
 867 }
 868 
 869 // Helper class used to cache a ClassFileMap for the instance fields of
 870 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
 871 // heap iteration and avoid creating a field map for each object in the heap
 872 // (only need to create the map when the first instance of a class is encountered).
 873 //
 874 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
 875  private:
 876    enum {
 877      initial_class_count = 200
 878    };
 879   ClassFieldMap* _field_map;
 880 
 881   ClassFieldMap* field_map() const          { return _field_map; }
 882 
 883   JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
 884   ~JvmtiCachedClassFieldMap();
 885 
 886   static GrowableArray<InstanceKlass*>* _class_list;
 887   static void add_to_class_list(InstanceKlass* ik);
 888 
 889  public:
 890   // returns the field map for a given object (returning map cached
 891   // by InstanceKlass if possible
 892   static ClassFieldMap* get_map_of_instance_fields(oop obj);
 893 
 894   // removes the field map from all instanceKlasses - should be
 895   // called before VM operation completes
 896   static void clear_cache();
 897 
 898   // returns the number of ClassFieldMap cached by instanceKlasses
 899   static int cached_field_map_count();
 900 };
 901 
 902 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
 903 
 904 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
 905   _field_map = field_map;
 906 }
 907 
 908 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
 909   if (_field_map != NULL) {
 910     delete _field_map;
 911   }
 912 }
 913 
 914 // Marker class to ensure that the class file map cache is only used in a defined
 915 // scope.
 916 class ClassFieldMapCacheMark : public StackObj {
 917  private:
 918    static bool _is_active;
 919  public:
 920    ClassFieldMapCacheMark() {
 921      assert(Thread::current()->is_VM_thread(), "must be VMThread");
 922      assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
 923      assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
 924      _is_active = true;
 925    }
 926    ~ClassFieldMapCacheMark() {
 927      JvmtiCachedClassFieldMap::clear_cache();
 928      _is_active = false;
 929    }
 930    static bool is_active() { return _is_active; }
 931 };
 932 
 933 bool ClassFieldMapCacheMark::_is_active;
 934 
 935 
 936 // record that the given InstanceKlass is caching a field map
 937 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
 938   if (_class_list == NULL) {
 939     _class_list = new (ResourceObj::C_HEAP, mtInternal)
 940       GrowableArray<InstanceKlass*>(initial_class_count, true);
 941   }
 942   _class_list->push(ik);
 943 }
 944 
 945 // returns the instance field map for the given object
 946 // (returns field map cached by the InstanceKlass if possible)
 947 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
 948   assert(Thread::current()->is_VM_thread(), "must be VMThread");
 949   assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
 950 
 951   Klass* k = obj->klass();
 952   InstanceKlass* ik = InstanceKlass::cast(k);
 953 
 954   // return cached map if possible
 955   JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
 956   if (cached_map != NULL) {
 957     assert(cached_map->field_map() != NULL, "missing field list");
 958     return cached_map->field_map();
 959   } else {
 960     ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
 961     cached_map = new JvmtiCachedClassFieldMap(field_map);
 962     ik->set_jvmti_cached_class_field_map(cached_map);
 963     add_to_class_list(ik);
 964     return field_map;
 965   }
 966 }
 967 
 968 // remove the fields maps cached from all instanceKlasses
 969 void JvmtiCachedClassFieldMap::clear_cache() {
 970   assert(Thread::current()->is_VM_thread(), "must be VMThread");
 971   if (_class_list != NULL) {
 972     for (int i = 0; i < _class_list->length(); i++) {
 973       InstanceKlass* ik = _class_list->at(i);
 974       JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
 975       assert(cached_map != NULL, "should not be NULL");
 976       ik->set_jvmti_cached_class_field_map(NULL);
 977       delete cached_map;  // deletes the encapsulated field map
 978     }
 979     delete _class_list;
 980     _class_list = NULL;
 981   }
 982 }
 983 
 984 // returns the number of ClassFieldMap cached by instanceKlasses
 985 int JvmtiCachedClassFieldMap::cached_field_map_count() {
 986   return (_class_list == NULL) ? 0 : _class_list->length();
 987 }
 988 
 989 // helper function to indicate if an object is filtered by its tag or class tag
 990 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
 991                                               jlong klass_tag,
 992                                               int heap_filter) {
 993   // apply the heap filter
 994   if (obj_tag != 0) {
 995     // filter out tagged objects
 996     if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
 997   } else {
 998     // filter out untagged objects
 999     if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
1000   }
1001   if (klass_tag != 0) {
1002     // filter out objects with tagged classes
1003     if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1004   } else {
1005     // filter out objects with untagged classes.
1006     if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1007   }
1008   return false;
1009 }
1010 
1011 // helper function to indicate if an object is filtered by a klass filter
1012 static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
1013   if (!klass_filter.is_null()) {
1014     if (obj->klass() != klass_filter()) {
1015       return true;
1016     }
1017   }
1018   return false;
1019 }
1020 
1021 // helper function to tell if a field is a primitive field or not
1022 static inline bool is_primitive_field_type(char type) {
1023   return (type != 'L' && type != '[');
1024 }
1025 
1026 // helper function to copy the value from location addr to jvalue.
1027 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1028   switch (value_type) {
1029     case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1030     case JVMTI_PRIMITIVE_TYPE_BYTE    : { v->b = *(jbyte*)addr;    break; }
1031     case JVMTI_PRIMITIVE_TYPE_CHAR    : { v->c = *(jchar*)addr;    break; }
1032     case JVMTI_PRIMITIVE_TYPE_SHORT   : { v->s = *(jshort*)addr;   break; }
1033     case JVMTI_PRIMITIVE_TYPE_INT     : { v->i = *(jint*)addr;     break; }
1034     case JVMTI_PRIMITIVE_TYPE_LONG    : { v->j = *(jlong*)addr;    break; }
1035     case JVMTI_PRIMITIVE_TYPE_FLOAT   : { v->f = *(jfloat*)addr;   break; }
1036     case JVMTI_PRIMITIVE_TYPE_DOUBLE  : { v->d = *(jdouble*)addr;  break; }
1037     default: ShouldNotReachHere();
1038   }
1039 }
1040 
1041 // helper function to invoke string primitive value callback
1042 // returns visit control flags
1043 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1044                                          CallbackWrapper* wrapper,
1045                                          oop str,
1046                                          void* user_data)
1047 {
1048   assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1049 
1050   typeArrayOop s_value = java_lang_String::value(str);
1051 
1052   // JDK-6584008: the value field may be null if a String instance is
1053   // partially constructed.
1054   if (s_value == NULL) {
1055     return 0;
1056   }
1057   // get the string value and length
1058   // (string value may be offset from the base)
1059   int s_len = java_lang_String::length(str);
1060   bool is_latin1 = java_lang_String::is_latin1(str);
1061   jchar* value;
1062   if (s_len > 0) {
1063     if (!is_latin1) {
1064       value = s_value->char_at_addr(0);
1065     } else {
1066       // Inflate latin1 encoded string to UTF16
1067       jchar* buf = NEW_C_HEAP_ARRAY(jchar, s_len, mtInternal);
1068       for (int i = 0; i < s_len; i++) {
1069         buf[i] = ((jchar) s_value->byte_at(i)) & 0xff;
1070       }
1071       value = &buf[0];
1072     }
1073   } else {
1074     // Don't use char_at_addr(0) if length is 0
1075     value = (jchar*) s_value->base(T_CHAR);
1076   }
1077 
1078   // invoke the callback
1079   jint res = (*cb)(wrapper->klass_tag(),
1080                    wrapper->obj_size(),
1081                    wrapper->obj_tag_p(),
1082                    value,
1083                    (jint)s_len,
1084                    user_data);
1085 
1086   if (is_latin1 && s_len > 0) {
1087     FREE_C_HEAP_ARRAY(jchar, value);
1088   }
1089   return res;
1090 }
1091 
1092 // helper function to invoke string primitive value callback
1093 // returns visit control flags
1094 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1095                                                   CallbackWrapper* wrapper,
1096                                                   oop obj,
1097                                                   void* user_data)
1098 {
1099   assert(obj->is_typeArray(), "not a primitive array");
1100 
1101   // get base address of first element
1102   typeArrayOop array = typeArrayOop(obj);
1103   BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
1104   void* elements = array->base(type);
1105 
1106   // jvmtiPrimitiveType is defined so this mapping is always correct
1107   jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1108 
1109   return (*cb)(wrapper->klass_tag(),
1110                wrapper->obj_size(),
1111                wrapper->obj_tag_p(),
1112                (jint)array->length(),
1113                elem_type,
1114                elements,
1115                user_data);
1116 }
1117 
1118 // helper function to invoke the primitive field callback for all static fields
1119 // of a given class
1120 static jint invoke_primitive_field_callback_for_static_fields
1121   (CallbackWrapper* wrapper,
1122    oop obj,
1123    jvmtiPrimitiveFieldCallback cb,
1124    void* user_data)
1125 {
1126   // for static fields only the index will be set
1127   static jvmtiHeapReferenceInfo reference_info = { 0 };
1128 
1129   assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1130   if (java_lang_Class::is_primitive(obj)) {
1131     return 0;
1132   }
1133   Klass* klass = java_lang_Class::as_Klass(obj);
1134 
1135   // ignore classes for object and type arrays
1136   if (!klass->oop_is_instance()) {
1137     return 0;
1138   }
1139 
1140   // ignore classes which aren't linked yet
1141   InstanceKlass* ik = InstanceKlass::cast(klass);
1142   if (!ik->is_linked()) {
1143     return 0;
1144   }
1145 
1146   // get the field map
1147   ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1148 
1149   // invoke the callback for each static primitive field
1150   for (int i=0; i<field_map->field_count(); i++) {
1151     ClassFieldDescriptor* field = field_map->field_at(i);
1152 
1153     // ignore non-primitive fields
1154     char type = field->field_type();
1155     if (!is_primitive_field_type(type)) {
1156       continue;
1157     }
1158     // one-to-one mapping
1159     jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1160 
1161     // get offset and field value
1162     int offset = field->field_offset();
1163     address addr = (address)klass->java_mirror() + offset;
1164     jvalue value;
1165     copy_to_jvalue(&value, addr, value_type);
1166 
1167     // field index
1168     reference_info.field.index = field->field_index();
1169 
1170     // invoke the callback
1171     jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1172                      &reference_info,
1173                      wrapper->klass_tag(),
1174                      wrapper->obj_tag_p(),
1175                      value,
1176                      value_type,
1177                      user_data);
1178     if (res & JVMTI_VISIT_ABORT) {
1179       delete field_map;
1180       return res;
1181     }
1182   }
1183 
1184   delete field_map;
1185   return 0;
1186 }
1187 
1188 // helper function to invoke the primitive field callback for all instance fields
1189 // of a given object
1190 static jint invoke_primitive_field_callback_for_instance_fields(
1191   CallbackWrapper* wrapper,
1192   oop obj,
1193   jvmtiPrimitiveFieldCallback cb,
1194   void* user_data)
1195 {
1196   // for instance fields only the index will be set
1197   static jvmtiHeapReferenceInfo reference_info = { 0 };
1198 
1199   // get the map of the instance fields
1200   ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1201 
1202   // invoke the callback for each instance primitive field
1203   for (int i=0; i<fields->field_count(); i++) {
1204     ClassFieldDescriptor* field = fields->field_at(i);
1205 
1206     // ignore non-primitive fields
1207     char type = field->field_type();
1208     if (!is_primitive_field_type(type)) {
1209       continue;
1210     }
1211     // one-to-one mapping
1212     jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1213 
1214     // get offset and field value
1215     int offset = field->field_offset();
1216     address addr = (address)obj + offset;
1217     jvalue value;
1218     copy_to_jvalue(&value, addr, value_type);
1219 
1220     // field index
1221     reference_info.field.index = field->field_index();
1222 
1223     // invoke the callback
1224     jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1225                      &reference_info,
1226                      wrapper->klass_tag(),
1227                      wrapper->obj_tag_p(),
1228                      value,
1229                      value_type,
1230                      user_data);
1231     if (res & JVMTI_VISIT_ABORT) {
1232       return res;
1233     }
1234   }
1235   return 0;
1236 }
1237 
1238 
1239 // VM operation to iterate over all objects in the heap (both reachable
1240 // and unreachable)
1241 class VM_HeapIterateOperation: public VM_Operation {
1242  private:
1243   ObjectClosure* _blk;
1244  public:
1245   VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1246 
1247   VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1248   void doit() {
1249     // allows class files maps to be cached during iteration
1250     ClassFieldMapCacheMark cm;
1251 
1252     // make sure that heap is parsable (fills TLABs with filler objects)
1253     Universe::heap()->ensure_parsability(false);  // no need to retire TLABs
1254 
1255     // Verify heap before iteration - if the heap gets corrupted then
1256     // JVMTI's IterateOverHeap will crash.
1257     if (VerifyBeforeIteration) {
1258       Universe::verify();
1259     }
1260 
1261     // do the iteration
1262     // If this operation encounters a bad object when using CMS,
1263     // consider using safe_object_iterate() which avoids perm gen
1264     // objects that may contain bad references.
1265     Universe::heap()->object_iterate(_blk);
1266   }
1267 
1268 };
1269 
1270 
1271 // An ObjectClosure used to support the deprecated IterateOverHeap and
1272 // IterateOverInstancesOfClass functions
1273 class IterateOverHeapObjectClosure: public ObjectClosure {
1274  private:
1275   JvmtiTagMap* _tag_map;
1276   KlassHandle _klass;
1277   jvmtiHeapObjectFilter _object_filter;
1278   jvmtiHeapObjectCallback _heap_object_callback;
1279   const void* _user_data;
1280 
1281   // accessors
1282   JvmtiTagMap* tag_map() const                    { return _tag_map; }
1283   jvmtiHeapObjectFilter object_filter() const     { return _object_filter; }
1284   jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1285   KlassHandle klass() const                       { return _klass; }
1286   const void* user_data() const                   { return _user_data; }
1287 
1288   // indicates if iteration has been aborted
1289   bool _iteration_aborted;
1290   bool is_iteration_aborted() const               { return _iteration_aborted; }
1291   void set_iteration_aborted(bool aborted)        { _iteration_aborted = aborted; }
1292 
1293  public:
1294   IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1295                                KlassHandle klass,
1296                                jvmtiHeapObjectFilter object_filter,
1297                                jvmtiHeapObjectCallback heap_object_callback,
1298                                const void* user_data) :
1299     _tag_map(tag_map),
1300     _klass(klass),
1301     _object_filter(object_filter),
1302     _heap_object_callback(heap_object_callback),
1303     _user_data(user_data),
1304     _iteration_aborted(false)
1305   {
1306   }
1307 
1308   void do_object(oop o);
1309 };
1310 
1311 // invoked for each object in the heap
1312 void IterateOverHeapObjectClosure::do_object(oop o) {
1313   // check if iteration has been halted
1314   if (is_iteration_aborted()) return;
1315 
1316   // ignore any objects that aren't visible to profiler
1317   if (!ServiceUtil::visible_oop(o)) return;
1318 
1319   // instanceof check when filtering by klass
1320   if (!klass().is_null() && !o->is_a(klass()())) {
1321     return;
1322   }
1323   // prepare for the calllback
1324   CallbackWrapper wrapper(tag_map(), o);
1325 
1326   // if the object is tagged and we're only interested in untagged objects
1327   // then don't invoke the callback. Similiarly, if the object is untagged
1328   // and we're only interested in tagged objects we skip the callback.
1329   if (wrapper.obj_tag() != 0) {
1330     if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1331   } else {
1332     if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1333   }
1334 
1335   // invoke the agent's callback
1336   jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1337                                                        wrapper.obj_size(),
1338                                                        wrapper.obj_tag_p(),
1339                                                        (void*)user_data());
1340   if (control == JVMTI_ITERATION_ABORT) {
1341     set_iteration_aborted(true);
1342   }
1343 }
1344 
1345 // An ObjectClosure used to support the IterateThroughHeap function
1346 class IterateThroughHeapObjectClosure: public ObjectClosure {
1347  private:
1348   JvmtiTagMap* _tag_map;
1349   KlassHandle _klass;
1350   int _heap_filter;
1351   const jvmtiHeapCallbacks* _callbacks;
1352   const void* _user_data;
1353 
1354   // accessor functions
1355   JvmtiTagMap* tag_map() const                     { return _tag_map; }
1356   int heap_filter() const                          { return _heap_filter; }
1357   const jvmtiHeapCallbacks* callbacks() const      { return _callbacks; }
1358   KlassHandle klass() const                        { return _klass; }
1359   const void* user_data() const                    { return _user_data; }
1360 
1361   // indicates if the iteration has been aborted
1362   bool _iteration_aborted;
1363   bool is_iteration_aborted() const                { return _iteration_aborted; }
1364 
1365   // used to check the visit control flags. If the abort flag is set
1366   // then we set the iteration aborted flag so that the iteration completes
1367   // without processing any further objects
1368   bool check_flags_for_abort(jint flags) {
1369     bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1370     if (is_abort) {
1371       _iteration_aborted = true;
1372     }
1373     return is_abort;
1374   }
1375 
1376  public:
1377   IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1378                                   KlassHandle klass,
1379                                   int heap_filter,
1380                                   const jvmtiHeapCallbacks* heap_callbacks,
1381                                   const void* user_data) :
1382     _tag_map(tag_map),
1383     _klass(klass),
1384     _heap_filter(heap_filter),
1385     _callbacks(heap_callbacks),
1386     _user_data(user_data),
1387     _iteration_aborted(false)
1388   {
1389   }
1390 
1391   void do_object(oop o);
1392 };
1393 
1394 // invoked for each object in the heap
1395 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1396   // check if iteration has been halted
1397   if (is_iteration_aborted()) return;
1398 
1399   // ignore any objects that aren't visible to profiler
1400   if (!ServiceUtil::visible_oop(obj)) return;
1401 
1402   // apply class filter
1403   if (is_filtered_by_klass_filter(obj, klass())) return;
1404 
1405   // prepare for callback
1406   CallbackWrapper wrapper(tag_map(), obj);
1407 
1408   // check if filtered by the heap filter
1409   if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1410     return;
1411   }
1412 
1413   // for arrays we need the length, otherwise -1
1414   bool is_array = obj->is_array();
1415   int len = is_array ? arrayOop(obj)->length() : -1;
1416 
1417   // invoke the object callback (if callback is provided)
1418   if (callbacks()->heap_iteration_callback != NULL) {
1419     jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1420     jint res = (*cb)(wrapper.klass_tag(),
1421                      wrapper.obj_size(),
1422                      wrapper.obj_tag_p(),
1423                      (jint)len,
1424                      (void*)user_data());
1425     if (check_flags_for_abort(res)) return;
1426   }
1427 
1428   // for objects and classes we report primitive fields if callback provided
1429   if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1430     jint res;
1431     jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1432     if (obj->klass() == SystemDictionary::Class_klass()) {
1433       res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1434                                                                     obj,
1435                                                                     cb,
1436                                                                     (void*)user_data());
1437     } else {
1438       res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1439                                                                       obj,
1440                                                                       cb,
1441                                                                       (void*)user_data());
1442     }
1443     if (check_flags_for_abort(res)) return;
1444   }
1445 
1446   // string callback
1447   if (!is_array &&
1448       callbacks()->string_primitive_value_callback != NULL &&
1449       obj->klass() == SystemDictionary::String_klass()) {
1450     jint res = invoke_string_value_callback(
1451                 callbacks()->string_primitive_value_callback,
1452                 &wrapper,
1453                 obj,
1454                 (void*)user_data() );
1455     if (check_flags_for_abort(res)) return;
1456   }
1457 
1458   // array callback
1459   if (is_array &&
1460       callbacks()->array_primitive_value_callback != NULL &&
1461       obj->is_typeArray()) {
1462     jint res = invoke_array_primitive_value_callback(
1463                callbacks()->array_primitive_value_callback,
1464                &wrapper,
1465                obj,
1466                (void*)user_data() );
1467     if (check_flags_for_abort(res)) return;
1468   }
1469 };
1470 
1471 
1472 // Deprecated function to iterate over all objects in the heap
1473 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1474                                     KlassHandle klass,
1475                                     jvmtiHeapObjectCallback heap_object_callback,
1476                                     const void* user_data)
1477 {
1478   MutexLocker ml(Heap_lock);
1479   IterateOverHeapObjectClosure blk(this,
1480                                    klass,
1481                                    object_filter,
1482                                    heap_object_callback,
1483                                    user_data);
1484   VM_HeapIterateOperation op(&blk);
1485   VMThread::execute(&op);
1486 }
1487 
1488 
1489 // Iterates over all objects in the heap
1490 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1491                                        KlassHandle klass,
1492                                        const jvmtiHeapCallbacks* callbacks,
1493                                        const void* user_data)
1494 {
1495   MutexLocker ml(Heap_lock);
1496   IterateThroughHeapObjectClosure blk(this,
1497                                       klass,
1498                                       heap_filter,
1499                                       callbacks,
1500                                       user_data);
1501   VM_HeapIterateOperation op(&blk);
1502   VMThread::execute(&op);
1503 }
1504 
1505 // support class for get_objects_with_tags
1506 
1507 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1508  private:
1509   JvmtiEnv* _env;
1510   jlong* _tags;
1511   jint _tag_count;
1512 
1513   GrowableArray<jobject>* _object_results;  // collected objects (JNI weak refs)
1514   GrowableArray<uint64_t>* _tag_results;    // collected tags
1515 
1516  public:
1517   TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1518     _env = env;
1519     _tags = (jlong*)tags;
1520     _tag_count = tag_count;
1521     _object_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<jobject>(1,true);
1522     _tag_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<uint64_t>(1,true);
1523   }
1524 
1525   ~TagObjectCollector() {
1526     delete _object_results;
1527     delete _tag_results;
1528   }
1529 
1530   // for each tagged object check if the tag value matches
1531   // - if it matches then we create a JNI local reference to the object
1532   // and record the reference and tag value.
1533   //
1534   void do_entry(JvmtiTagHashmapEntry* entry) {
1535     for (int i=0; i<_tag_count; i++) {
1536       if (_tags[i] == entry->tag()) {
1537         oop o = entry->object();
1538         assert(o != NULL && Universe::heap()->is_in_reserved(o), "sanity check");
1539         jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1540         _object_results->append(ref);
1541         _tag_results->append((uint64_t)entry->tag());
1542       }
1543     }
1544   }
1545 
1546   // return the results from the collection
1547   //
1548   jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1549     jvmtiError error;
1550     int count = _object_results->length();
1551     assert(count >= 0, "sanity check");
1552 
1553     // if object_result_ptr is not NULL then allocate the result and copy
1554     // in the object references.
1555     if (object_result_ptr != NULL) {
1556       error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1557       if (error != JVMTI_ERROR_NONE) {
1558         return error;
1559       }
1560       for (int i=0; i<count; i++) {
1561         (*object_result_ptr)[i] = _object_results->at(i);
1562       }
1563     }
1564 
1565     // if tag_result_ptr is not NULL then allocate the result and copy
1566     // in the tag values.
1567     if (tag_result_ptr != NULL) {
1568       error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1569       if (error != JVMTI_ERROR_NONE) {
1570         if (object_result_ptr != NULL) {
1571           _env->Deallocate((unsigned char*)object_result_ptr);
1572         }
1573         return error;
1574       }
1575       for (int i=0; i<count; i++) {
1576         (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1577       }
1578     }
1579 
1580     *count_ptr = count;
1581     return JVMTI_ERROR_NONE;
1582   }
1583 };
1584 
1585 // return the list of objects with the specified tags
1586 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1587   jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1588 
1589   TagObjectCollector collector(env(), tags, count);
1590   {
1591     // iterate over all tagged objects
1592     MutexLocker ml(lock());
1593     entry_iterate(&collector);
1594   }
1595   return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1596 }
1597 
1598 
1599 // ObjectMarker is used to support the marking objects when walking the
1600 // heap.
1601 //
1602 // This implementation uses the existing mark bits in an object for
1603 // marking. Objects that are marked must later have their headers restored.
1604 // As most objects are unlocked and don't have their identity hash computed
1605 // we don't have to save their headers. Instead we save the headers that
1606 // are "interesting". Later when the headers are restored this implementation
1607 // restores all headers to their initial value and then restores the few
1608 // objects that had interesting headers.
1609 //
1610 // Future work: This implementation currently uses growable arrays to save
1611 // the oop and header of interesting objects. As an optimization we could
1612 // use the same technique as the GC and make use of the unused area
1613 // between top() and end().
1614 //
1615 
1616 // An ObjectClosure used to restore the mark bits of an object
1617 class RestoreMarksClosure : public ObjectClosure {
1618  public:
1619   void do_object(oop o) {
1620     if (o != NULL) {
1621       markOop mark = o->mark();
1622       if (mark->is_marked()) {
1623         o->init_mark();
1624       }
1625     }
1626   }
1627 };
1628 
1629 // ObjectMarker provides the mark and visited functions
1630 class ObjectMarker : AllStatic {
1631  private:
1632   // saved headers
1633   static GrowableArray<oop>* _saved_oop_stack;
1634   static GrowableArray<markOop>* _saved_mark_stack;
1635   static bool _needs_reset;                  // do we need to reset mark bits?
1636 
1637  public:
1638   static void init();                       // initialize
1639   static void done();                       // clean-up
1640 
1641   static inline void mark(oop o);           // mark an object
1642   static inline bool visited(oop o);        // check if object has been visited
1643 
1644   static inline bool needs_reset()            { return _needs_reset; }
1645   static inline void set_needs_reset(bool v)  { _needs_reset = v; }
1646 };
1647 
1648 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1649 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1650 bool ObjectMarker::_needs_reset = true;  // need to reset mark bits by default
1651 
1652 // initialize ObjectMarker - prepares for object marking
1653 void ObjectMarker::init() {
1654   assert(Thread::current()->is_VM_thread(), "must be VMThread");
1655 
1656   // prepare heap for iteration
1657   Universe::heap()->ensure_parsability(false);  // no need to retire TLABs
1658 
1659   // create stacks for interesting headers
1660   _saved_mark_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<markOop>(4000, true);
1661   _saved_oop_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(4000, true);
1662 
1663   if (UseBiasedLocking) {
1664     BiasedLocking::preserve_marks();
1665   }
1666 }
1667 
1668 // Object marking is done so restore object headers
1669 void ObjectMarker::done() {
1670   // iterate over all objects and restore the mark bits to
1671   // their initial value
1672   RestoreMarksClosure blk;
1673   if (needs_reset()) {
1674     Universe::heap()->object_iterate(&blk);
1675   } else {
1676     // We don't need to reset mark bits on this call, but reset the
1677     // flag to the default for the next call.
1678     set_needs_reset(true);
1679   }
1680 
1681   // now restore the interesting headers
1682   for (int i = 0; i < _saved_oop_stack->length(); i++) {
1683     oop o = _saved_oop_stack->at(i);
1684     markOop mark = _saved_mark_stack->at(i);
1685     o->set_mark(mark);
1686   }
1687 
1688   if (UseBiasedLocking) {
1689     BiasedLocking::restore_marks();
1690   }
1691 
1692   // free the stacks
1693   delete _saved_oop_stack;
1694   delete _saved_mark_stack;
1695 }
1696 
1697 // mark an object
1698 inline void ObjectMarker::mark(oop o) {
1699   assert(Universe::heap()->is_in(o), "sanity check");
1700   assert(!o->mark()->is_marked(), "should only mark an object once");
1701 
1702   // object's mark word
1703   markOop mark = o->mark();
1704 
1705   if (mark->must_be_preserved(o)) {
1706     _saved_mark_stack->push(mark);
1707     _saved_oop_stack->push(o);
1708   }
1709 
1710   // mark the object
1711   o->set_mark(markOopDesc::prototype()->set_marked());
1712 }
1713 
1714 // return true if object is marked
1715 inline bool ObjectMarker::visited(oop o) {
1716   return o->mark()->is_marked();
1717 }
1718 
1719 // Stack allocated class to help ensure that ObjectMarker is used
1720 // correctly. Constructor initializes ObjectMarker, destructor calls
1721 // ObjectMarker's done() function to restore object headers.
1722 class ObjectMarkerController : public StackObj {
1723  public:
1724   ObjectMarkerController() {
1725     ObjectMarker::init();
1726   }
1727   ~ObjectMarkerController() {
1728     ObjectMarker::done();
1729   }
1730 };
1731 
1732 
1733 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1734 // (not performance critical as only used for roots)
1735 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1736   switch (kind) {
1737     case JVMTI_HEAP_REFERENCE_JNI_GLOBAL:   return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1738     case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1739     case JVMTI_HEAP_REFERENCE_MONITOR:      return JVMTI_HEAP_ROOT_MONITOR;
1740     case JVMTI_HEAP_REFERENCE_STACK_LOCAL:  return JVMTI_HEAP_ROOT_STACK_LOCAL;
1741     case JVMTI_HEAP_REFERENCE_JNI_LOCAL:    return JVMTI_HEAP_ROOT_JNI_LOCAL;
1742     case JVMTI_HEAP_REFERENCE_THREAD:       return JVMTI_HEAP_ROOT_THREAD;
1743     case JVMTI_HEAP_REFERENCE_OTHER:        return JVMTI_HEAP_ROOT_OTHER;
1744     default: ShouldNotReachHere();          return JVMTI_HEAP_ROOT_OTHER;
1745   }
1746 }
1747 
1748 // Base class for all heap walk contexts. The base class maintains a flag
1749 // to indicate if the context is valid or not.
1750 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1751  private:
1752   bool _valid;
1753  public:
1754   HeapWalkContext(bool valid)                   { _valid = valid; }
1755   void invalidate()                             { _valid = false; }
1756   bool is_valid() const                         { return _valid; }
1757 };
1758 
1759 // A basic heap walk context for the deprecated heap walking functions.
1760 // The context for a basic heap walk are the callbacks and fields used by
1761 // the referrer caching scheme.
1762 class BasicHeapWalkContext: public HeapWalkContext {
1763  private:
1764   jvmtiHeapRootCallback _heap_root_callback;
1765   jvmtiStackReferenceCallback _stack_ref_callback;
1766   jvmtiObjectReferenceCallback _object_ref_callback;
1767 
1768   // used for caching
1769   oop _last_referrer;
1770   jlong _last_referrer_tag;
1771 
1772  public:
1773   BasicHeapWalkContext() : HeapWalkContext(false) { }
1774 
1775   BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1776                        jvmtiStackReferenceCallback stack_ref_callback,
1777                        jvmtiObjectReferenceCallback object_ref_callback) :
1778     HeapWalkContext(true),
1779     _heap_root_callback(heap_root_callback),
1780     _stack_ref_callback(stack_ref_callback),
1781     _object_ref_callback(object_ref_callback),
1782     _last_referrer(NULL),
1783     _last_referrer_tag(0) {
1784   }
1785 
1786   // accessors
1787   jvmtiHeapRootCallback heap_root_callback() const         { return _heap_root_callback; }
1788   jvmtiStackReferenceCallback stack_ref_callback() const   { return _stack_ref_callback; }
1789   jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback;  }
1790 
1791   oop last_referrer() const               { return _last_referrer; }
1792   void set_last_referrer(oop referrer)    { _last_referrer = referrer; }
1793   jlong last_referrer_tag() const         { return _last_referrer_tag; }
1794   void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1795 };
1796 
1797 // The advanced heap walk context for the FollowReferences functions.
1798 // The context is the callbacks, and the fields used for filtering.
1799 class AdvancedHeapWalkContext: public HeapWalkContext {
1800  private:
1801   jint _heap_filter;
1802   KlassHandle _klass_filter;
1803   const jvmtiHeapCallbacks* _heap_callbacks;
1804 
1805  public:
1806   AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1807 
1808   AdvancedHeapWalkContext(jint heap_filter,
1809                            KlassHandle klass_filter,
1810                            const jvmtiHeapCallbacks* heap_callbacks) :
1811     HeapWalkContext(true),
1812     _heap_filter(heap_filter),
1813     _klass_filter(klass_filter),
1814     _heap_callbacks(heap_callbacks) {
1815   }
1816 
1817   // accessors
1818   jint heap_filter() const         { return _heap_filter; }
1819   KlassHandle klass_filter() const { return _klass_filter; }
1820 
1821   const jvmtiHeapReferenceCallback heap_reference_callback() const {
1822     return _heap_callbacks->heap_reference_callback;
1823   };
1824   const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1825     return _heap_callbacks->primitive_field_callback;
1826   }
1827   const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1828     return _heap_callbacks->array_primitive_value_callback;
1829   }
1830   const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1831     return _heap_callbacks->string_primitive_value_callback;
1832   }
1833 };
1834 
1835 // The CallbackInvoker is a class with static functions that the heap walk can call
1836 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1837 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1838 // mode is for the newer FollowReferences function which supports a lot of
1839 // additional callbacks.
1840 class CallbackInvoker : AllStatic {
1841  private:
1842   // heap walk styles
1843   enum { basic, advanced };
1844   static int _heap_walk_type;
1845   static bool is_basic_heap_walk()           { return _heap_walk_type == basic; }
1846   static bool is_advanced_heap_walk()        { return _heap_walk_type == advanced; }
1847 
1848   // context for basic style heap walk
1849   static BasicHeapWalkContext _basic_context;
1850   static BasicHeapWalkContext* basic_context() {
1851     assert(_basic_context.is_valid(), "invalid");
1852     return &_basic_context;
1853   }
1854 
1855   // context for advanced style heap walk
1856   static AdvancedHeapWalkContext _advanced_context;
1857   static AdvancedHeapWalkContext* advanced_context() {
1858     assert(_advanced_context.is_valid(), "invalid");
1859     return &_advanced_context;
1860   }
1861 
1862   // context needed for all heap walks
1863   static JvmtiTagMap* _tag_map;
1864   static const void* _user_data;
1865   static GrowableArray<oop>* _visit_stack;
1866 
1867   // accessors
1868   static JvmtiTagMap* tag_map()                        { return _tag_map; }
1869   static const void* user_data()                       { return _user_data; }
1870   static GrowableArray<oop>* visit_stack()             { return _visit_stack; }
1871 
1872   // if the object hasn't been visited then push it onto the visit stack
1873   // so that it will be visited later
1874   static inline bool check_for_visit(oop obj) {
1875     if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1876     return true;
1877   }
1878 
1879   // invoke basic style callbacks
1880   static inline bool invoke_basic_heap_root_callback
1881     (jvmtiHeapRootKind root_kind, oop obj);
1882   static inline bool invoke_basic_stack_ref_callback
1883     (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1884      int slot, oop obj);
1885   static inline bool invoke_basic_object_reference_callback
1886     (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1887 
1888   // invoke advanced style callbacks
1889   static inline bool invoke_advanced_heap_root_callback
1890     (jvmtiHeapReferenceKind ref_kind, oop obj);
1891   static inline bool invoke_advanced_stack_ref_callback
1892     (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1893      jmethodID method, jlocation bci, jint slot, oop obj);
1894   static inline bool invoke_advanced_object_reference_callback
1895     (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1896 
1897   // used to report the value of primitive fields
1898   static inline bool report_primitive_field
1899     (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1900 
1901  public:
1902   // initialize for basic mode
1903   static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1904                                              GrowableArray<oop>* visit_stack,
1905                                              const void* user_data,
1906                                              BasicHeapWalkContext context);
1907 
1908   // initialize for advanced mode
1909   static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1910                                                 GrowableArray<oop>* visit_stack,
1911                                                 const void* user_data,
1912                                                 AdvancedHeapWalkContext context);
1913 
1914    // functions to report roots
1915   static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
1916   static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1917     jmethodID m, oop o);
1918   static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1919     jmethodID method, jlocation bci, jint slot, oop o);
1920 
1921   // functions to report references
1922   static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
1923   static inline bool report_class_reference(oop referrer, oop referree);
1924   static inline bool report_class_loader_reference(oop referrer, oop referree);
1925   static inline bool report_signers_reference(oop referrer, oop referree);
1926   static inline bool report_protection_domain_reference(oop referrer, oop referree);
1927   static inline bool report_superclass_reference(oop referrer, oop referree);
1928   static inline bool report_interface_reference(oop referrer, oop referree);
1929   static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
1930   static inline bool report_field_reference(oop referrer, oop referree, jint slot);
1931   static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
1932   static inline bool report_primitive_array_values(oop array);
1933   static inline bool report_string_value(oop str);
1934   static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
1935   static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
1936 };
1937 
1938 // statics
1939 int CallbackInvoker::_heap_walk_type;
1940 BasicHeapWalkContext CallbackInvoker::_basic_context;
1941 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1942 JvmtiTagMap* CallbackInvoker::_tag_map;
1943 const void* CallbackInvoker::_user_data;
1944 GrowableArray<oop>* CallbackInvoker::_visit_stack;
1945 
1946 // initialize for basic heap walk (IterateOverReachableObjects et al)
1947 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1948                                                      GrowableArray<oop>* visit_stack,
1949                                                      const void* user_data,
1950                                                      BasicHeapWalkContext context) {
1951   _tag_map = tag_map;
1952   _visit_stack = visit_stack;
1953   _user_data = user_data;
1954   _basic_context = context;
1955   _advanced_context.invalidate();       // will trigger assertion if used
1956   _heap_walk_type = basic;
1957 }
1958 
1959 // initialize for advanced heap walk (FollowReferences)
1960 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1961                                                         GrowableArray<oop>* visit_stack,
1962                                                         const void* user_data,
1963                                                         AdvancedHeapWalkContext context) {
1964   _tag_map = tag_map;
1965   _visit_stack = visit_stack;
1966   _user_data = user_data;
1967   _advanced_context = context;
1968   _basic_context.invalidate();      // will trigger assertion if used
1969   _heap_walk_type = advanced;
1970 }
1971 
1972 
1973 // invoke basic style heap root callback
1974 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
1975   assert(ServiceUtil::visible_oop(obj), "checking");
1976 
1977   // if we heap roots should be reported
1978   jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1979   if (cb == NULL) {
1980     return check_for_visit(obj);
1981   }
1982 
1983   CallbackWrapper wrapper(tag_map(), obj);
1984   jvmtiIterationControl control = (*cb)(root_kind,
1985                                         wrapper.klass_tag(),
1986                                         wrapper.obj_size(),
1987                                         wrapper.obj_tag_p(),
1988                                         (void*)user_data());
1989   // push root to visit stack when following references
1990   if (control == JVMTI_ITERATION_CONTINUE &&
1991       basic_context()->object_ref_callback() != NULL) {
1992     visit_stack()->push(obj);
1993   }
1994   return control != JVMTI_ITERATION_ABORT;
1995 }
1996 
1997 // invoke basic style stack ref callback
1998 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
1999                                                              jlong thread_tag,
2000                                                              jint depth,
2001                                                              jmethodID method,
2002                                                              jint slot,
2003                                                              oop obj) {
2004   assert(ServiceUtil::visible_oop(obj), "checking");
2005 
2006   // if we stack refs should be reported
2007   jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
2008   if (cb == NULL) {
2009     return check_for_visit(obj);
2010   }
2011 
2012   CallbackWrapper wrapper(tag_map(), obj);
2013   jvmtiIterationControl control = (*cb)(root_kind,
2014                                         wrapper.klass_tag(),
2015                                         wrapper.obj_size(),
2016                                         wrapper.obj_tag_p(),
2017                                         thread_tag,
2018                                         depth,
2019                                         method,
2020                                         slot,
2021                                         (void*)user_data());
2022   // push root to visit stack when following references
2023   if (control == JVMTI_ITERATION_CONTINUE &&
2024       basic_context()->object_ref_callback() != NULL) {
2025     visit_stack()->push(obj);
2026   }
2027   return control != JVMTI_ITERATION_ABORT;
2028 }
2029 
2030 // invoke basic style object reference callback
2031 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2032                                                                     oop referrer,
2033                                                                     oop referree,
2034                                                                     jint index) {
2035 
2036   assert(ServiceUtil::visible_oop(referrer), "checking");
2037   assert(ServiceUtil::visible_oop(referree), "checking");
2038 
2039   BasicHeapWalkContext* context = basic_context();
2040 
2041   // callback requires the referrer's tag. If it's the same referrer
2042   // as the last call then we use the cached value.
2043   jlong referrer_tag;
2044   if (referrer == context->last_referrer()) {
2045     referrer_tag = context->last_referrer_tag();
2046   } else {
2047     referrer_tag = tag_for(tag_map(), referrer);
2048   }
2049 
2050   // do the callback
2051   CallbackWrapper wrapper(tag_map(), referree);
2052   jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2053   jvmtiIterationControl control = (*cb)(ref_kind,
2054                                         wrapper.klass_tag(),
2055                                         wrapper.obj_size(),
2056                                         wrapper.obj_tag_p(),
2057                                         referrer_tag,
2058                                         index,
2059                                         (void*)user_data());
2060 
2061   // record referrer and referrer tag. For self-references record the
2062   // tag value from the callback as this might differ from referrer_tag.
2063   context->set_last_referrer(referrer);
2064   if (referrer == referree) {
2065     context->set_last_referrer_tag(*wrapper.obj_tag_p());
2066   } else {
2067     context->set_last_referrer_tag(referrer_tag);
2068   }
2069 
2070   if (control == JVMTI_ITERATION_CONTINUE) {
2071     return check_for_visit(referree);
2072   } else {
2073     return control != JVMTI_ITERATION_ABORT;
2074   }
2075 }
2076 
2077 // invoke advanced style heap root callback
2078 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2079                                                                 oop obj) {
2080   assert(ServiceUtil::visible_oop(obj), "checking");
2081 
2082   AdvancedHeapWalkContext* context = advanced_context();
2083 
2084   // check that callback is provided
2085   jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2086   if (cb == NULL) {
2087     return check_for_visit(obj);
2088   }
2089 
2090   // apply class filter
2091   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2092     return check_for_visit(obj);
2093   }
2094 
2095   // setup the callback wrapper
2096   CallbackWrapper wrapper(tag_map(), obj);
2097 
2098   // apply tag filter
2099   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2100                                  wrapper.klass_tag(),
2101                                  context->heap_filter())) {
2102     return check_for_visit(obj);
2103   }
2104 
2105   // for arrays we need the length, otherwise -1
2106   jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2107 
2108   // invoke the callback
2109   jint res  = (*cb)(ref_kind,
2110                     NULL, // referrer info
2111                     wrapper.klass_tag(),
2112                     0,    // referrer_class_tag is 0 for heap root
2113                     wrapper.obj_size(),
2114                     wrapper.obj_tag_p(),
2115                     NULL, // referrer_tag_p
2116                     len,
2117                     (void*)user_data());
2118   if (res & JVMTI_VISIT_ABORT) {
2119     return false;// referrer class tag
2120   }
2121   if (res & JVMTI_VISIT_OBJECTS) {
2122     check_for_visit(obj);
2123   }
2124   return true;
2125 }
2126 
2127 // report a reference from a thread stack to an object
2128 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2129                                                                 jlong thread_tag,
2130                                                                 jlong tid,
2131                                                                 int depth,
2132                                                                 jmethodID method,
2133                                                                 jlocation bci,
2134                                                                 jint slot,
2135                                                                 oop obj) {
2136   assert(ServiceUtil::visible_oop(obj), "checking");
2137 
2138   AdvancedHeapWalkContext* context = advanced_context();
2139 
2140   // check that callback is provider
2141   jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2142   if (cb == NULL) {
2143     return check_for_visit(obj);
2144   }
2145 
2146   // apply class filter
2147   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2148     return check_for_visit(obj);
2149   }
2150 
2151   // setup the callback wrapper
2152   CallbackWrapper wrapper(tag_map(), obj);
2153 
2154   // apply tag filter
2155   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2156                                  wrapper.klass_tag(),
2157                                  context->heap_filter())) {
2158     return check_for_visit(obj);
2159   }
2160 
2161   // setup the referrer info
2162   jvmtiHeapReferenceInfo reference_info;
2163   reference_info.stack_local.thread_tag = thread_tag;
2164   reference_info.stack_local.thread_id = tid;
2165   reference_info.stack_local.depth = depth;
2166   reference_info.stack_local.method = method;
2167   reference_info.stack_local.location = bci;
2168   reference_info.stack_local.slot = slot;
2169 
2170   // for arrays we need the length, otherwise -1
2171   jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2172 
2173   // call into the agent
2174   int res = (*cb)(ref_kind,
2175                   &reference_info,
2176                   wrapper.klass_tag(),
2177                   0,    // referrer_class_tag is 0 for heap root (stack)
2178                   wrapper.obj_size(),
2179                   wrapper.obj_tag_p(),
2180                   NULL, // referrer_tag is 0 for root
2181                   len,
2182                   (void*)user_data());
2183 
2184   if (res & JVMTI_VISIT_ABORT) {
2185     return false;
2186   }
2187   if (res & JVMTI_VISIT_OBJECTS) {
2188     check_for_visit(obj);
2189   }
2190   return true;
2191 }
2192 
2193 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2194 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2195 #define REF_INFO_MASK  ((1 << JVMTI_HEAP_REFERENCE_FIELD)         \
2196                       | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD)  \
2197                       | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2198                       | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2199                       | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL)   \
2200                       | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2201 
2202 // invoke the object reference callback to report a reference
2203 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2204                                                                        oop referrer,
2205                                                                        oop obj,
2206                                                                        jint index)
2207 {
2208   // field index is only valid field in reference_info
2209   static jvmtiHeapReferenceInfo reference_info = { 0 };
2210 
2211   assert(ServiceUtil::visible_oop(referrer), "checking");
2212   assert(ServiceUtil::visible_oop(obj), "checking");
2213 
2214   AdvancedHeapWalkContext* context = advanced_context();
2215 
2216   // check that callback is provider
2217   jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2218   if (cb == NULL) {
2219     return check_for_visit(obj);
2220   }
2221 
2222   // apply class filter
2223   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2224     return check_for_visit(obj);
2225   }
2226 
2227   // setup the callback wrapper
2228   TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2229 
2230   // apply tag filter
2231   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2232                                  wrapper.klass_tag(),
2233                                  context->heap_filter())) {
2234     return check_for_visit(obj);
2235   }
2236 
2237   // field index is only valid field in reference_info
2238   reference_info.field.index = index;
2239 
2240   // for arrays we need the length, otherwise -1
2241   jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2242 
2243   // invoke the callback
2244   int res = (*cb)(ref_kind,
2245                   (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2246                   wrapper.klass_tag(),
2247                   wrapper.referrer_klass_tag(),
2248                   wrapper.obj_size(),
2249                   wrapper.obj_tag_p(),
2250                   wrapper.referrer_tag_p(),
2251                   len,
2252                   (void*)user_data());
2253 
2254   if (res & JVMTI_VISIT_ABORT) {
2255     return false;
2256   }
2257   if (res & JVMTI_VISIT_OBJECTS) {
2258     check_for_visit(obj);
2259   }
2260   return true;
2261 }
2262 
2263 // report a "simple root"
2264 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2265   assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2266          kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2267   assert(ServiceUtil::visible_oop(obj), "checking");
2268 
2269   if (is_basic_heap_walk()) {
2270     // map to old style root kind
2271     jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2272     return invoke_basic_heap_root_callback(root_kind, obj);
2273   } else {
2274     assert(is_advanced_heap_walk(), "wrong heap walk type");
2275     return invoke_advanced_heap_root_callback(kind, obj);
2276   }
2277 }
2278 
2279 
2280 // invoke the primitive array values
2281 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2282   assert(obj->is_typeArray(), "not a primitive array");
2283 
2284   AdvancedHeapWalkContext* context = advanced_context();
2285   assert(context->array_primitive_value_callback() != NULL, "no callback");
2286 
2287   // apply class filter
2288   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2289     return true;
2290   }
2291 
2292   CallbackWrapper wrapper(tag_map(), obj);
2293 
2294   // apply tag filter
2295   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2296                                  wrapper.klass_tag(),
2297                                  context->heap_filter())) {
2298     return true;
2299   }
2300 
2301   // invoke the callback
2302   int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2303                                                   &wrapper,
2304                                                   obj,
2305                                                   (void*)user_data());
2306   return (!(res & JVMTI_VISIT_ABORT));
2307 }
2308 
2309 // invoke the string value callback
2310 inline bool CallbackInvoker::report_string_value(oop str) {
2311   assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2312 
2313   AdvancedHeapWalkContext* context = advanced_context();
2314   assert(context->string_primitive_value_callback() != NULL, "no callback");
2315 
2316   // apply class filter
2317   if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2318     return true;
2319   }
2320 
2321   CallbackWrapper wrapper(tag_map(), str);
2322 
2323   // apply tag filter
2324   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2325                                  wrapper.klass_tag(),
2326                                  context->heap_filter())) {
2327     return true;
2328   }
2329 
2330   // invoke the callback
2331   int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2332                                          &wrapper,
2333                                          str,
2334                                          (void*)user_data());
2335   return (!(res & JVMTI_VISIT_ABORT));
2336 }
2337 
2338 // invoke the primitive field callback
2339 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2340                                                     oop obj,
2341                                                     jint index,
2342                                                     address addr,
2343                                                     char type)
2344 {
2345   // for primitive fields only the index will be set
2346   static jvmtiHeapReferenceInfo reference_info = { 0 };
2347 
2348   AdvancedHeapWalkContext* context = advanced_context();
2349   assert(context->primitive_field_callback() != NULL, "no callback");
2350 
2351   // apply class filter
2352   if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2353     return true;
2354   }
2355 
2356   CallbackWrapper wrapper(tag_map(), obj);
2357 
2358   // apply tag filter
2359   if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2360                                  wrapper.klass_tag(),
2361                                  context->heap_filter())) {
2362     return true;
2363   }
2364 
2365   // the field index in the referrer
2366   reference_info.field.index = index;
2367 
2368   // map the type
2369   jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2370 
2371   // setup the jvalue
2372   jvalue value;
2373   copy_to_jvalue(&value, addr, value_type);
2374 
2375   jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2376   int res = (*cb)(ref_kind,
2377                   &reference_info,
2378                   wrapper.klass_tag(),
2379                   wrapper.obj_tag_p(),
2380                   value,
2381                   value_type,
2382                   (void*)user_data());
2383   return (!(res & JVMTI_VISIT_ABORT));
2384 }
2385 
2386 
2387 // instance field
2388 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2389                                                              jint index,
2390                                                              address value,
2391                                                              char type) {
2392   return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2393                                 obj,
2394                                 index,
2395                                 value,
2396                                 type);
2397 }
2398 
2399 // static field
2400 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2401                                                            jint index,
2402                                                            address value,
2403                                                            char type) {
2404   return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2405                                 obj,
2406                                 index,
2407                                 value,
2408                                 type);
2409 }
2410 
2411 // report a JNI local (root object) to the profiler
2412 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2413   if (is_basic_heap_walk()) {
2414     return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2415                                            thread_tag,
2416                                            depth,
2417                                            m,
2418                                            -1,
2419                                            obj);
2420   } else {
2421     return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2422                                               thread_tag, tid,
2423                                               depth,
2424                                               m,
2425                                               (jlocation)-1,
2426                                               -1,
2427                                               obj);
2428   }
2429 }
2430 
2431 
2432 // report a local (stack reference, root object)
2433 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2434                                                    jlong tid,
2435                                                    jint depth,
2436                                                    jmethodID method,
2437                                                    jlocation bci,
2438                                                    jint slot,
2439                                                    oop obj) {
2440   if (is_basic_heap_walk()) {
2441     return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2442                                            thread_tag,
2443                                            depth,
2444                                            method,
2445                                            slot,
2446                                            obj);
2447   } else {
2448     return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2449                                               thread_tag,
2450                                               tid,
2451                                               depth,
2452                                               method,
2453                                               bci,
2454                                               slot,
2455                                               obj);
2456   }
2457 }
2458 
2459 // report an object referencing a class.
2460 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2461   if (is_basic_heap_walk()) {
2462     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2463   } else {
2464     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2465   }
2466 }
2467 
2468 // report a class referencing its class loader.
2469 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2470   if (is_basic_heap_walk()) {
2471     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2472   } else {
2473     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2474   }
2475 }
2476 
2477 // report a class referencing its signers.
2478 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2479   if (is_basic_heap_walk()) {
2480     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2481   } else {
2482     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2483   }
2484 }
2485 
2486 // report a class referencing its protection domain..
2487 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2488   if (is_basic_heap_walk()) {
2489     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2490   } else {
2491     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2492   }
2493 }
2494 
2495 // report a class referencing its superclass.
2496 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2497   if (is_basic_heap_walk()) {
2498     // Send this to be consistent with past implementation
2499     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2500   } else {
2501     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2502   }
2503 }
2504 
2505 // report a class referencing one of its interfaces.
2506 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2507   if (is_basic_heap_walk()) {
2508     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2509   } else {
2510     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2511   }
2512 }
2513 
2514 // report a class referencing one of its static fields.
2515 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2516   if (is_basic_heap_walk()) {
2517     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2518   } else {
2519     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2520   }
2521 }
2522 
2523 // report an array referencing an element object
2524 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2525   if (is_basic_heap_walk()) {
2526     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2527   } else {
2528     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2529   }
2530 }
2531 
2532 // report an object referencing an instance field object
2533 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2534   if (is_basic_heap_walk()) {
2535     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2536   } else {
2537     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2538   }
2539 }
2540 
2541 // report an array referencing an element object
2542 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2543   if (is_basic_heap_walk()) {
2544     return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2545   } else {
2546     return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2547   }
2548 }
2549 
2550 // A supporting closure used to process simple roots
2551 class SimpleRootsClosure : public OopClosure {
2552  private:
2553   jvmtiHeapReferenceKind _kind;
2554   bool _continue;
2555 
2556   jvmtiHeapReferenceKind root_kind()    { return _kind; }
2557 
2558  public:
2559   void set_kind(jvmtiHeapReferenceKind kind) {
2560     _kind = kind;
2561     _continue = true;
2562   }
2563 
2564   inline bool stopped() {
2565     return !_continue;
2566   }
2567 
2568   void do_oop(oop* obj_p) {
2569     // iteration has terminated
2570     if (stopped()) {
2571       return;
2572     }
2573 
2574     // ignore null or deleted handles
2575     oop o = *obj_p;
2576     if (o == NULL || o == JNIHandles::deleted_handle()) {
2577       return;
2578     }
2579 
2580     assert(Universe::heap()->is_in_reserved(o), "should be impossible");
2581 
2582     jvmtiHeapReferenceKind kind = root_kind();
2583     if (kind == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2584       // SystemDictionary::always_strong_oops_do reports the application
2585       // class loader as a root. We want this root to be reported as
2586       // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2587       if (!o->is_instanceMirror()) {
2588         kind = JVMTI_HEAP_REFERENCE_OTHER;
2589       }
2590     }
2591 
2592     // some objects are ignored - in the case of simple
2593     // roots it's mostly Symbol*s that we are skipping
2594     // here.
2595     if (!ServiceUtil::visible_oop(o)) {
2596       return;
2597     }
2598 
2599     // invoke the callback
2600     _continue = CallbackInvoker::report_simple_root(kind, o);
2601 
2602   }
2603   virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2604 };
2605 
2606 // A supporting closure used to process JNI locals
2607 class JNILocalRootsClosure : public OopClosure {
2608  private:
2609   jlong _thread_tag;
2610   jlong _tid;
2611   jint _depth;
2612   jmethodID _method;
2613   bool _continue;
2614  public:
2615   void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2616     _thread_tag = thread_tag;
2617     _tid = tid;
2618     _depth = depth;
2619     _method = method;
2620     _continue = true;
2621   }
2622 
2623   inline bool stopped() {
2624     return !_continue;
2625   }
2626 
2627   void do_oop(oop* obj_p) {
2628     // iteration has terminated
2629     if (stopped()) {
2630       return;
2631     }
2632 
2633     // ignore null or deleted handles
2634     oop o = *obj_p;
2635     if (o == NULL || o == JNIHandles::deleted_handle()) {
2636       return;
2637     }
2638 
2639     if (!ServiceUtil::visible_oop(o)) {
2640       return;
2641     }
2642 
2643     // invoke the callback
2644     _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2645   }
2646   virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2647 };
2648 
2649 
2650 // A VM operation to iterate over objects that are reachable from
2651 // a set of roots or an initial object.
2652 //
2653 // For VM_HeapWalkOperation the set of roots used is :-
2654 //
2655 // - All JNI global references
2656 // - All inflated monitors
2657 // - All classes loaded by the boot class loader (or all classes
2658 //     in the event that class unloading is disabled)
2659 // - All java threads
2660 // - For each java thread then all locals and JNI local references
2661 //      on the thread's execution stack
2662 // - All visible/explainable objects from Universes::oops_do
2663 //
2664 class VM_HeapWalkOperation: public VM_Operation {
2665  private:
2666   enum {
2667     initial_visit_stack_size = 4000
2668   };
2669 
2670   bool _is_advanced_heap_walk;                      // indicates FollowReferences
2671   JvmtiTagMap* _tag_map;
2672   Handle _initial_object;
2673   GrowableArray<oop>* _visit_stack;                 // the visit stack
2674 
2675   bool _collecting_heap_roots;                      // are we collecting roots
2676   bool _following_object_refs;                      // are we following object references
2677 
2678   bool _reporting_primitive_fields;                 // optional reporting
2679   bool _reporting_primitive_array_values;
2680   bool _reporting_string_values;
2681 
2682   GrowableArray<oop>* create_visit_stack() {
2683     return new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(initial_visit_stack_size, true);
2684   }
2685 
2686   // accessors
2687   bool is_advanced_heap_walk() const               { return _is_advanced_heap_walk; }
2688   JvmtiTagMap* tag_map() const                     { return _tag_map; }
2689   Handle initial_object() const                    { return _initial_object; }
2690 
2691   bool is_following_references() const             { return _following_object_refs; }
2692 
2693   bool is_reporting_primitive_fields()  const      { return _reporting_primitive_fields; }
2694   bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2695   bool is_reporting_string_values() const          { return _reporting_string_values; }
2696 
2697   GrowableArray<oop>* visit_stack() const          { return _visit_stack; }
2698 
2699   // iterate over the various object types
2700   inline bool iterate_over_array(oop o);
2701   inline bool iterate_over_type_array(oop o);
2702   inline bool iterate_over_class(oop o);
2703   inline bool iterate_over_object(oop o);
2704 
2705   // root collection
2706   inline bool collect_simple_roots();
2707   inline bool collect_stack_roots();
2708   inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2709 
2710   // visit an object
2711   inline bool visit(oop o);
2712 
2713  public:
2714   VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2715                        Handle initial_object,
2716                        BasicHeapWalkContext callbacks,
2717                        const void* user_data);
2718 
2719   VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2720                        Handle initial_object,
2721                        AdvancedHeapWalkContext callbacks,
2722                        const void* user_data);
2723 
2724   ~VM_HeapWalkOperation();
2725 
2726   VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2727   void doit();
2728 };
2729 
2730 
2731 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2732                                            Handle initial_object,
2733                                            BasicHeapWalkContext callbacks,
2734                                            const void* user_data) {
2735   _is_advanced_heap_walk = false;
2736   _tag_map = tag_map;
2737   _initial_object = initial_object;
2738   _following_object_refs = (callbacks.object_ref_callback() != NULL);
2739   _reporting_primitive_fields = false;
2740   _reporting_primitive_array_values = false;
2741   _reporting_string_values = false;
2742   _visit_stack = create_visit_stack();
2743 
2744 
2745   CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2746 }
2747 
2748 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2749                                            Handle initial_object,
2750                                            AdvancedHeapWalkContext callbacks,
2751                                            const void* user_data) {
2752   _is_advanced_heap_walk = true;
2753   _tag_map = tag_map;
2754   _initial_object = initial_object;
2755   _following_object_refs = true;
2756   _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2757   _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2758   _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2759   _visit_stack = create_visit_stack();
2760 
2761   CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2762 }
2763 
2764 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2765   if (_following_object_refs) {
2766     assert(_visit_stack != NULL, "checking");
2767     delete _visit_stack;
2768     _visit_stack = NULL;
2769   }
2770 }
2771 
2772 // an array references its class and has a reference to
2773 // each element in the array
2774 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2775   objArrayOop array = objArrayOop(o);
2776 
2777   // array reference to its class
2778   oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
2779   if (!CallbackInvoker::report_class_reference(o, mirror)) {
2780     return false;
2781   }
2782 
2783   // iterate over the array and report each reference to a
2784   // non-null element
2785   for (int index=0; index<array->length(); index++) {
2786     oop elem = array->obj_at(index);
2787     if (elem == NULL) {
2788       continue;
2789     }
2790 
2791     // report the array reference o[index] = elem
2792     if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2793       return false;
2794     }
2795   }
2796   return true;
2797 }
2798 
2799 // a type array references its class
2800 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2801   Klass* k = o->klass();
2802   oop mirror = k->java_mirror();
2803   if (!CallbackInvoker::report_class_reference(o, mirror)) {
2804     return false;
2805   }
2806 
2807   // report the array contents if required
2808   if (is_reporting_primitive_array_values()) {
2809     if (!CallbackInvoker::report_primitive_array_values(o)) {
2810       return false;
2811     }
2812   }
2813   return true;
2814 }
2815 
2816 #ifdef ASSERT
2817 // verify that a static oop field is in range
2818 static inline bool verify_static_oop(InstanceKlass* ik,
2819                                      oop mirror, int offset) {
2820   address obj_p = (address)mirror + offset;
2821   address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2822   address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2823   assert(end >= start, "sanity check");
2824 
2825   if (obj_p >= start && obj_p < end) {
2826     return true;
2827   } else {
2828     return false;
2829   }
2830 }
2831 #endif // #ifdef ASSERT
2832 
2833 // a class references its super class, interfaces, class loader, ...
2834 // and finally its static fields
2835 inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) {
2836   int i;
2837   Klass* klass = java_lang_Class::as_Klass(java_class);
2838 
2839   if (klass->oop_is_instance()) {
2840     InstanceKlass* ik = InstanceKlass::cast(klass);
2841 
2842     // Ignore the class if it hasn't been initialized yet
2843     if (!ik->is_linked()) {
2844       return true;
2845     }
2846 
2847     // get the java mirror
2848     oop mirror = klass->java_mirror();
2849 
2850     // super (only if something more interesting than java.lang.Object)
2851     Klass* java_super = ik->java_super();
2852     if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2853       oop super = java_super->java_mirror();
2854       if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2855         return false;
2856       }
2857     }
2858 
2859     // class loader
2860     oop cl = ik->class_loader();
2861     if (cl != NULL) {
2862       if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2863         return false;
2864       }
2865     }
2866 
2867     // protection domain
2868     oop pd = ik->protection_domain();
2869     if (pd != NULL) {
2870       if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2871         return false;
2872       }
2873     }
2874 
2875     // signers
2876     oop signers = ik->signers();
2877     if (signers != NULL) {
2878       if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2879         return false;
2880       }
2881     }
2882 
2883     // references from the constant pool
2884     {
2885       ConstantPool* pool = ik->constants();
2886       for (int i = 1; i < pool->length(); i++) {
2887         constantTag tag = pool->tag_at(i).value();
2888         if (tag.is_string() || tag.is_klass()) {
2889           oop entry;
2890           if (tag.is_string()) {
2891             entry = pool->resolved_string_at(i);
2892             // If the entry is non-null it is resolved.
2893             if (entry == NULL) continue;
2894           } else {
2895             entry = pool->resolved_klass_at(i)->java_mirror();
2896           }
2897           if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2898             return false;
2899           }
2900         }
2901       }
2902     }
2903 
2904     // interfaces
2905     // (These will already have been reported as references from the constant pool
2906     //  but are specified by IterateOverReachableObjects and must be reported).
2907     Array<Klass*>* interfaces = ik->local_interfaces();
2908     for (i = 0; i < interfaces->length(); i++) {
2909       oop interf = ((Klass*)interfaces->at(i))->java_mirror();
2910       if (interf == NULL) {
2911         continue;
2912       }
2913       if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
2914         return false;
2915       }
2916     }
2917 
2918     // iterate over the static fields
2919 
2920     ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
2921     for (i=0; i<field_map->field_count(); i++) {
2922       ClassFieldDescriptor* field = field_map->field_at(i);
2923       char type = field->field_type();
2924       if (!is_primitive_field_type(type)) {
2925         oop fld_o = mirror->obj_field(field->field_offset());
2926         assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check");
2927         if (fld_o != NULL) {
2928           int slot = field->field_index();
2929           if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
2930             delete field_map;
2931             return false;
2932           }
2933         }
2934       } else {
2935          if (is_reporting_primitive_fields()) {
2936            address addr = (address)mirror + field->field_offset();
2937            int slot = field->field_index();
2938            if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
2939              delete field_map;
2940              return false;
2941           }
2942         }
2943       }
2944     }
2945     delete field_map;
2946 
2947     return true;
2948   }
2949 
2950   return true;
2951 }
2952 
2953 // an object references a class and its instance fields
2954 // (static fields are ignored here as we report these as
2955 // references from the class).
2956 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
2957   // reference to the class
2958   if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) {
2959     return false;
2960   }
2961 
2962   // iterate over instance fields
2963   ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
2964   for (int i=0; i<field_map->field_count(); i++) {
2965     ClassFieldDescriptor* field = field_map->field_at(i);
2966     char type = field->field_type();
2967     if (!is_primitive_field_type(type)) {
2968       oop fld_o = o->obj_field(field->field_offset());
2969       // ignore any objects that aren't visible to profiler
2970       if (fld_o != NULL && ServiceUtil::visible_oop(fld_o)) {
2971         assert(Universe::heap()->is_in_reserved(fld_o), "unsafe code should not "
2972                "have references to Klass* anymore");
2973         int slot = field->field_index();
2974         if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
2975           return false;
2976         }
2977       }
2978     } else {
2979       if (is_reporting_primitive_fields()) {
2980         // primitive instance field
2981         address addr = (address)o + field->field_offset();
2982         int slot = field->field_index();
2983         if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
2984           return false;
2985         }
2986       }
2987     }
2988   }
2989 
2990   // if the object is a java.lang.String
2991   if (is_reporting_string_values() &&
2992       o->klass() == SystemDictionary::String_klass()) {
2993     if (!CallbackInvoker::report_string_value(o)) {
2994       return false;
2995     }
2996   }
2997   return true;
2998 }
2999 
3000 
3001 // Collects all simple (non-stack) roots except for threads;
3002 // threads are handled in collect_stack_roots() as an optimization.
3003 // if there's a heap root callback provided then the callback is
3004 // invoked for each simple root.
3005 // if an object reference callback is provided then all simple
3006 // roots are pushed onto the marking stack so that they can be
3007 // processed later
3008 //
3009 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3010   SimpleRootsClosure blk;
3011 
3012   // JNI globals
3013   blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3014   JNIHandles::oops_do(&blk);
3015   if (blk.stopped()) {
3016     return false;
3017   }
3018 
3019   // Preloaded classes and loader from the system dictionary
3020   blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3021   SystemDictionary::always_strong_oops_do(&blk);
3022   KlassToOopClosure klass_blk(&blk);
3023   ClassLoaderDataGraph::always_strong_oops_do(&blk, &klass_blk, false);
3024   if (blk.stopped()) {
3025     return false;
3026   }
3027 
3028   // Inflated monitors
3029   blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3030   ObjectSynchronizer::oops_do(&blk);
3031   if (blk.stopped()) {
3032     return false;
3033   }
3034 
3035   // threads are now handled in collect_stack_roots()
3036 
3037   // Other kinds of roots maintained by HotSpot
3038   // Many of these won't be visible but others (such as instances of important
3039   // exceptions) will be visible.
3040   blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3041   Universe::oops_do(&blk);
3042 
3043   // If there are any non-perm roots in the code cache, visit them.
3044   blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3045   CodeBlobToOopClosure look_in_blobs(&blk, !CodeBlobToOopClosure::FixRelocations);
3046   CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3047 
3048   return true;
3049 }
3050 
3051 // Walk the stack of a given thread and find all references (locals
3052 // and JNI calls) and report these as stack references
3053 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3054                                                       JNILocalRootsClosure* blk)
3055 {
3056   oop threadObj = java_thread->threadObj();
3057   assert(threadObj != NULL, "sanity check");
3058 
3059   // only need to get the thread's tag once per thread
3060   jlong thread_tag = tag_for(_tag_map, threadObj);
3061 
3062   // also need the thread id
3063   jlong tid = java_lang_Thread::thread_id(threadObj);
3064 
3065 
3066   if (java_thread->has_last_Java_frame()) {
3067 
3068     // vframes are resource allocated
3069     Thread* current_thread = Thread::current();
3070     ResourceMark rm(current_thread);
3071     HandleMark hm(current_thread);
3072 
3073     RegisterMap reg_map(java_thread);
3074     frame f = java_thread->last_frame();
3075     vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
3076 
3077     bool is_top_frame = true;
3078     int depth = 0;
3079     frame* last_entry_frame = NULL;
3080 
3081     while (vf != NULL) {
3082       if (vf->is_java_frame()) {
3083 
3084         // java frame (interpreted, compiled, ...)
3085         javaVFrame *jvf = javaVFrame::cast(vf);
3086 
3087         // the jmethodID
3088         jmethodID method = jvf->method()->jmethod_id();
3089 
3090         if (!(jvf->method()->is_native())) {
3091           jlocation bci = (jlocation)jvf->bci();
3092           StackValueCollection* locals = jvf->locals();
3093           for (int slot=0; slot<locals->size(); slot++) {
3094             if (locals->at(slot)->type() == T_OBJECT) {
3095               oop o = locals->obj_at(slot)();
3096               if (o == NULL) {
3097                 continue;
3098               }
3099 
3100               // stack reference
3101               if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3102                                                    bci, slot, o)) {
3103                 return false;
3104               }
3105             }
3106           }
3107 
3108           StackValueCollection* exprs = jvf->expressions();
3109           for (int index=0; index < exprs->size(); index++) {
3110             if (exprs->at(index)->type() == T_OBJECT) {
3111               oop o = exprs->obj_at(index)();
3112               if (o == NULL) {
3113                 continue;
3114               }
3115 
3116               // stack reference
3117               if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3118                                                    bci, locals->size() + index, o)) {
3119                 return false;
3120               }
3121             }
3122           }
3123 
3124         } else {
3125           blk->set_context(thread_tag, tid, depth, method);
3126           if (is_top_frame) {
3127             // JNI locals for the top frame.
3128             java_thread->active_handles()->oops_do(blk);
3129           } else {
3130             if (last_entry_frame != NULL) {
3131               // JNI locals for the entry frame
3132               assert(last_entry_frame->is_entry_frame(), "checking");
3133               last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3134             }
3135           }
3136         }
3137         last_entry_frame = NULL;
3138         depth++;
3139       } else {
3140         // externalVFrame - for an entry frame then we report the JNI locals
3141         // when we find the corresponding javaVFrame
3142         frame* fr = vf->frame_pointer();
3143         assert(fr != NULL, "sanity check");
3144         if (fr->is_entry_frame()) {
3145           last_entry_frame = fr;
3146         }
3147       }
3148 
3149       vf = vf->sender();
3150       is_top_frame = false;
3151     }
3152   } else {
3153     // no last java frame but there may be JNI locals
3154     blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3155     java_thread->active_handles()->oops_do(blk);
3156   }
3157   return true;
3158 }
3159 
3160 
3161 // Collects the simple roots for all threads and collects all
3162 // stack roots - for each thread it walks the execution
3163 // stack to find all references and local JNI refs.
3164 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3165   JNILocalRootsClosure blk;
3166   for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3167     oop threadObj = thread->threadObj();
3168     if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3169       // Collect the simple root for this thread before we
3170       // collect its stack roots
3171       if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD,
3172                                                threadObj)) {
3173         return false;
3174       }
3175       if (!collect_stack_roots(thread, &blk)) {
3176         return false;
3177       }
3178     }
3179   }
3180   return true;
3181 }
3182 
3183 // visit an object
3184 // first mark the object as visited
3185 // second get all the outbound references from this object (in other words, all
3186 // the objects referenced by this object).
3187 //
3188 bool VM_HeapWalkOperation::visit(oop o) {
3189   // mark object as visited
3190   assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3191   ObjectMarker::mark(o);
3192 
3193   // instance
3194   if (o->is_instance()) {
3195     if (o->klass() == SystemDictionary::Class_klass()) {
3196       if (!java_lang_Class::is_primitive(o)) {
3197         // a java.lang.Class
3198         return iterate_over_class(o);
3199       }
3200     } else {
3201       return iterate_over_object(o);
3202     }
3203   }
3204 
3205   // object array
3206   if (o->is_objArray()) {
3207     return iterate_over_array(o);
3208   }
3209 
3210   // type array
3211   if (o->is_typeArray()) {
3212     return iterate_over_type_array(o);
3213   }
3214 
3215   return true;
3216 }
3217 
3218 void VM_HeapWalkOperation::doit() {
3219   ResourceMark rm;
3220   ObjectMarkerController marker;
3221   ClassFieldMapCacheMark cm;
3222 
3223   assert(visit_stack()->is_empty(), "visit stack must be empty");
3224 
3225   // the heap walk starts with an initial object or the heap roots
3226   if (initial_object().is_null()) {
3227     // If either collect_stack_roots() or collect_simple_roots()
3228     // returns false at this point, then there are no mark bits
3229     // to reset.
3230     ObjectMarker::set_needs_reset(false);
3231 
3232     // Calling collect_stack_roots() before collect_simple_roots()
3233     // can result in a big performance boost for an agent that is
3234     // focused on analyzing references in the thread stacks.
3235     if (!collect_stack_roots()) return;
3236 
3237     if (!collect_simple_roots()) return;
3238 
3239     // no early return so enable heap traversal to reset the mark bits
3240     ObjectMarker::set_needs_reset(true);
3241   } else {
3242     visit_stack()->push(initial_object()());
3243   }
3244 
3245   // object references required
3246   if (is_following_references()) {
3247 
3248     // visit each object until all reachable objects have been
3249     // visited or the callback asked to terminate the iteration.
3250     while (!visit_stack()->is_empty()) {
3251       oop o = visit_stack()->pop();
3252       if (!ObjectMarker::visited(o)) {
3253         if (!visit(o)) {
3254           break;
3255         }
3256       }
3257     }
3258   }
3259 }
3260 
3261 // iterate over all objects that are reachable from a set of roots
3262 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3263                                                  jvmtiStackReferenceCallback stack_ref_callback,
3264                                                  jvmtiObjectReferenceCallback object_ref_callback,
3265                                                  const void* user_data) {
3266   MutexLocker ml(Heap_lock);
3267   BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3268   VM_HeapWalkOperation op(this, Handle(), context, user_data);
3269   VMThread::execute(&op);
3270 }
3271 
3272 // iterate over all objects that are reachable from a given object
3273 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3274                                                              jvmtiObjectReferenceCallback object_ref_callback,
3275                                                              const void* user_data) {
3276   oop obj = JNIHandles::resolve(object);
3277   Handle initial_object(Thread::current(), obj);
3278 
3279   MutexLocker ml(Heap_lock);
3280   BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3281   VM_HeapWalkOperation op(this, initial_object, context, user_data);
3282   VMThread::execute(&op);
3283 }
3284 
3285 // follow references from an initial object or the GC roots
3286 void JvmtiTagMap::follow_references(jint heap_filter,
3287                                     KlassHandle klass,
3288                                     jobject object,
3289                                     const jvmtiHeapCallbacks* callbacks,
3290                                     const void* user_data)
3291 {
3292   oop obj = JNIHandles::resolve(object);
3293   Handle initial_object(Thread::current(), obj);
3294 
3295   MutexLocker ml(Heap_lock);
3296   AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3297   VM_HeapWalkOperation op(this, initial_object, context, user_data);
3298   VMThread::execute(&op);
3299 }
3300 
3301 
3302 void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
3303   // No locks during VM bring-up (0 threads) and no safepoints after main
3304   // thread creation and before VMThread creation (1 thread); initial GC
3305   // verification can happen in that window which gets to here.
3306   assert(Threads::number_of_threads() <= 1 ||
3307          SafepointSynchronize::is_at_safepoint(),
3308          "must be executed at a safepoint");
3309   if (JvmtiEnv::environments_might_exist()) {
3310     JvmtiEnvIterator it;
3311     for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3312       JvmtiTagMap* tag_map = env->tag_map();
3313       if (tag_map != NULL && !tag_map->is_empty()) {
3314         tag_map->do_weak_oops(is_alive, f);
3315       }
3316     }
3317   }
3318 }
3319 
3320 void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
3321 
3322   // does this environment have the OBJECT_FREE event enabled
3323   bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3324 
3325   // counters used for trace message
3326   int freed = 0;
3327   int moved = 0;
3328 
3329   JvmtiTagHashmap* hashmap = this->hashmap();
3330 
3331   // reenable sizing (if disabled)
3332   hashmap->set_resizing_enabled(true);
3333 
3334   // if the hashmap is empty then we can skip it
3335   if (hashmap->_entry_count == 0) {
3336     return;
3337   }
3338 
3339   // now iterate through each entry in the table
3340 
3341   JvmtiTagHashmapEntry** table = hashmap->table();
3342   int size = hashmap->size();
3343 
3344   JvmtiTagHashmapEntry* delayed_add = NULL;
3345 
3346   for (int pos = 0; pos < size; ++pos) {
3347     JvmtiTagHashmapEntry* entry = table[pos];
3348     JvmtiTagHashmapEntry* prev = NULL;
3349 
3350     while (entry != NULL) {
3351       JvmtiTagHashmapEntry* next = entry->next();
3352 
3353       oop* obj = entry->object_addr();
3354 
3355       // has object been GC'ed
3356       if (!is_alive->do_object_b(entry->object())) {
3357         // grab the tag
3358         jlong tag = entry->tag();
3359         guarantee(tag != 0, "checking");
3360 
3361         // remove GC'ed entry from hashmap and return the
3362         // entry to the free list
3363         hashmap->remove(prev, pos, entry);
3364         destroy_entry(entry);
3365 
3366         // post the event to the profiler
3367         if (post_object_free) {
3368           JvmtiExport::post_object_free(env(), tag);
3369         }
3370 
3371         ++freed;
3372       } else {
3373         f->do_oop(entry->object_addr());
3374         oop new_oop = entry->object();
3375 
3376         // if the object has moved then re-hash it and move its
3377         // entry to its new location.
3378         unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
3379         if (new_pos != (unsigned int)pos) {
3380           if (prev == NULL) {
3381             table[pos] = next;
3382           } else {
3383             prev->set_next(next);
3384           }
3385           if (new_pos < (unsigned int)pos) {
3386             entry->set_next(table[new_pos]);
3387             table[new_pos] = entry;
3388           } else {
3389             // Delay adding this entry to it's new position as we'd end up
3390             // hitting it again during this iteration.
3391             entry->set_next(delayed_add);
3392             delayed_add = entry;
3393           }
3394           moved++;
3395         } else {
3396           // object didn't move
3397           prev = entry;
3398         }
3399       }
3400 
3401       entry = next;
3402     }
3403   }
3404 
3405   // Re-add all the entries which were kept aside
3406   while (delayed_add != NULL) {
3407     JvmtiTagHashmapEntry* next = delayed_add->next();
3408     unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
3409     delayed_add->set_next(table[pos]);
3410     table[pos] = delayed_add;
3411     delayed_add = next;
3412   }
3413 
3414   // stats
3415   if (TraceJVMTIObjectTagging) {
3416     int post_total = hashmap->_entry_count;
3417     int pre_total = post_total + freed;
3418 
3419     tty->print_cr("(%d->%d, %d freed, %d total moves)",
3420         pre_total, post_total, freed, moved);
3421   }
3422 }