1 /*
2 * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/javaClasses.inline.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "jvmtifiles/jvmtiEnv.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "oops/instanceMirrorKlass.hpp"
34 #include "oops/objArrayKlass.hpp"
35 #include "oops/objArrayOop.inline.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "prims/jvmtiEventController.hpp"
38 #include "prims/jvmtiEventController.inline.hpp"
39 #include "prims/jvmtiExport.hpp"
40 #include "prims/jvmtiImpl.hpp"
41 #include "prims/jvmtiTagMap.hpp"
42 #include "runtime/biasedLocking.hpp"
43 #include "runtime/javaCalls.hpp"
44 #include "runtime/jniHandles.hpp"
45 #include "runtime/mutex.hpp"
46 #include "runtime/mutexLocker.hpp"
47 #include "runtime/reflectionUtils.hpp"
48 #include "runtime/vframe.hpp"
49 #include "runtime/vmThread.hpp"
50 #include "runtime/vm_operations.hpp"
51 #include "services/serviceUtil.hpp"
52 #include "utilities/macros.hpp"
53 #if INCLUDE_ALL_GCS
54 #include "gc/parallel/parallelScavengeHeap.hpp"
55 #endif // INCLUDE_ALL_GCS
56
57 // JvmtiTagHashmapEntry
58 //
59 // Each entry encapsulates a reference to the tagged object
60 // and the tag value. In addition an entry includes a next pointer which
61 // is used to chain entries together.
62
63 class JvmtiTagHashmapEntry : public CHeapObj<mtInternal> {
64 private:
65 friend class JvmtiTagMap;
66
67 oop _object; // tagged object
68 jlong _tag; // the tag
69 JvmtiTagHashmapEntry* _next; // next on the list
70
71 inline void init(oop object, jlong tag) {
72 _object = object;
73 _tag = tag;
74 _next = NULL;
75 }
76
77 // constructor
78 JvmtiTagHashmapEntry(oop object, jlong tag) { init(object, tag); }
79
80 public:
81
82 // accessor methods
83 inline oop object() const { return _object; }
84 inline oop* object_addr() { return &_object; }
85 inline jlong tag() const { return _tag; }
86
87 inline void set_tag(jlong tag) {
88 assert(tag != 0, "can't be zero");
89 _tag = tag;
90 }
91
92 inline JvmtiTagHashmapEntry* next() const { return _next; }
93 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; }
94 };
95
96
97 // JvmtiTagHashmap
98 //
99 // A hashmap is essentially a table of pointers to entries. Entries
100 // are hashed to a location, or position in the table, and then
101 // chained from that location. The "key" for hashing is address of
102 // the object, or oop. The "value" is the tag value.
103 //
104 // A hashmap maintains a count of the number entries in the hashmap
105 // and resizes if the number of entries exceeds a given threshold.
106 // The threshold is specified as a percentage of the size - for
107 // example a threshold of 0.75 will trigger the hashmap to resize
108 // if the number of entries is >75% of table size.
109 //
110 // A hashmap provides functions for adding, removing, and finding
111 // entries. It also provides a function to iterate over all entries
112 // in the hashmap.
113
114 class JvmtiTagHashmap : public CHeapObj<mtInternal> {
115 private:
116 friend class JvmtiTagMap;
117
118 enum {
119 small_trace_threshold = 10000, // threshold for tracing
120 medium_trace_threshold = 100000,
121 large_trace_threshold = 1000000,
122 initial_trace_threshold = small_trace_threshold
123 };
124
125 static int _sizes[]; // array of possible hashmap sizes
126 int _size; // actual size of the table
127 int _size_index; // index into size table
128
129 int _entry_count; // number of entries in the hashmap
130
131 float _load_factor; // load factor as a % of the size
132 int _resize_threshold; // computed threshold to trigger resizing.
133 bool _resizing_enabled; // indicates if hashmap can resize
134
135 int _trace_threshold; // threshold for trace messages
136
137 JvmtiTagHashmapEntry** _table; // the table of entries.
138
139 // private accessors
140 int resize_threshold() const { return _resize_threshold; }
141 int trace_threshold() const { return _trace_threshold; }
142
143 // initialize the hashmap
144 void init(int size_index=0, float load_factor=4.0f) {
145 int initial_size = _sizes[size_index];
146 _size_index = size_index;
147 _size = initial_size;
148 _entry_count = 0;
149 _trace_threshold = initial_trace_threshold;
150 _load_factor = load_factor;
151 _resize_threshold = (int)(_load_factor * _size);
152 _resizing_enabled = true;
153 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
154 _table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
155 if (_table == NULL) {
156 vm_exit_out_of_memory(s, OOM_MALLOC_ERROR,
157 "unable to allocate initial hashtable for jvmti object tags");
158 }
159 for (int i=0; i<initial_size; i++) {
160 _table[i] = NULL;
161 }
162 }
163
164 // hash a given key (oop) with the specified size
165 static unsigned int hash(oop key, int size) {
166 // shift right to get better distribution (as these bits will be zero
167 // with aligned addresses)
168 unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key));
169 #ifdef _LP64
170 return (addr >> 3) % size;
171 #else
172 return (addr >> 2) % size;
173 #endif
174 }
175
176 // hash a given key (oop)
177 unsigned int hash(oop key) {
178 return hash(key, _size);
179 }
180
181 // resize the hashmap - allocates a large table and re-hashes
182 // all entries into the new table.
183 void resize() {
184 int new_size_index = _size_index+1;
185 int new_size = _sizes[new_size_index];
186 if (new_size < 0) {
187 // hashmap already at maximum capacity
188 return;
189 }
190
191 // allocate new table
192 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
193 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
194 if (new_table == NULL) {
195 warning("unable to allocate larger hashtable for jvmti object tags");
196 set_resizing_enabled(false);
197 return;
198 }
199
200 // initialize new table
201 int i;
202 for (i=0; i<new_size; i++) {
203 new_table[i] = NULL;
204 }
205
206 // rehash all entries into the new table
207 for (i=0; i<_size; i++) {
208 JvmtiTagHashmapEntry* entry = _table[i];
209 while (entry != NULL) {
210 JvmtiTagHashmapEntry* next = entry->next();
211 oop key = entry->object();
212 assert(key != NULL, "jni weak reference cleared!!");
213 unsigned int h = hash(key, new_size);
214 JvmtiTagHashmapEntry* anchor = new_table[h];
215 if (anchor == NULL) {
216 new_table[h] = entry;
217 entry->set_next(NULL);
218 } else {
219 entry->set_next(anchor);
220 new_table[h] = entry;
221 }
222 entry = next;
223 }
224 }
225
226 // free old table and update settings.
227 os::free((void*)_table);
228 _table = new_table;
229 _size_index = new_size_index;
230 _size = new_size;
231
232 // compute new resize threshold
233 _resize_threshold = (int)(_load_factor * _size);
234 }
235
236
237 // internal remove function - remove an entry at a given position in the
238 // table.
239 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
240 assert(pos >= 0 && pos < _size, "out of range");
241 if (prev == NULL) {
242 _table[pos] = entry->next();
243 } else {
244 prev->set_next(entry->next());
245 }
246 assert(_entry_count > 0, "checking");
247 _entry_count--;
248 }
249
250 // resizing switch
251 bool is_resizing_enabled() const { return _resizing_enabled; }
252 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; }
253
254 // debugging
255 void print_memory_usage();
256 void compute_next_trace_threshold();
257
258 public:
259
260 // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
261 // The preferred size is rounded down to an actual size.
262 JvmtiTagHashmap(int size, float load_factor=0.0f) {
263 int i=0;
264 while (_sizes[i] < size) {
265 if (_sizes[i] < 0) {
266 assert(i > 0, "sanity check");
267 i--;
268 break;
269 }
270 i++;
271 }
272
273 // if a load factor is specified then use it, otherwise use default
274 if (load_factor > 0.01f) {
275 init(i, load_factor);
276 } else {
277 init(i);
278 }
279 }
280
281 // create a JvmtiTagHashmap with default settings
282 JvmtiTagHashmap() {
283 init();
284 }
285
286 // release table when JvmtiTagHashmap destroyed
287 ~JvmtiTagHashmap() {
288 if (_table != NULL) {
289 os::free((void*)_table);
290 _table = NULL;
291 }
292 }
293
294 // accessors
295 int size() const { return _size; }
296 JvmtiTagHashmapEntry** table() const { return _table; }
297 int entry_count() const { return _entry_count; }
298
299 // find an entry in the hashmap, returns NULL if not found.
300 inline JvmtiTagHashmapEntry* find(oop key) {
301 unsigned int h = hash(key);
302 JvmtiTagHashmapEntry* entry = _table[h];
303 while (entry != NULL) {
304 if (entry->object() == key) {
305 return entry;
306 }
307 entry = entry->next();
308 }
309 return NULL;
310 }
311
312
313 // add a new entry to hashmap
314 inline void add(oop key, JvmtiTagHashmapEntry* entry) {
315 assert(key != NULL, "checking");
316 assert(find(key) == NULL, "duplicate detected");
317 unsigned int h = hash(key);
318 JvmtiTagHashmapEntry* anchor = _table[h];
319 if (anchor == NULL) {
320 _table[h] = entry;
321 entry->set_next(NULL);
322 } else {
323 entry->set_next(anchor);
324 _table[h] = entry;
325 }
326
327 _entry_count++;
328 if (log_is_enabled(Debug, jvmti, objecttagging) && entry_count() >= trace_threshold()) {
329 print_memory_usage();
330 compute_next_trace_threshold();
331 }
332
333 // if the number of entries exceed the threshold then resize
334 if (entry_count() > resize_threshold() && is_resizing_enabled()) {
335 resize();
336 }
337 }
338
339 // remove an entry with the given key.
340 inline JvmtiTagHashmapEntry* remove(oop key) {
341 unsigned int h = hash(key);
342 JvmtiTagHashmapEntry* entry = _table[h];
343 JvmtiTagHashmapEntry* prev = NULL;
344 while (entry != NULL) {
345 if (key == entry->object()) {
346 break;
347 }
348 prev = entry;
349 entry = entry->next();
350 }
351 if (entry != NULL) {
352 remove(prev, h, entry);
353 }
354 return entry;
355 }
356
357 // iterate over all entries in the hashmap
358 void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
359 };
360
361 // possible hashmap sizes - odd primes that roughly double in size.
362 // To avoid excessive resizing the odd primes from 4801-76831 and
363 // 76831-307261 have been removed. The list must be terminated by -1.
364 int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891,
365 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
366
367
368 // A supporting class for iterating over all entries in Hashmap
369 class JvmtiTagHashmapEntryClosure {
370 public:
371 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
372 };
373
374
375 // iterate over all entries in the hashmap
376 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
377 for (int i=0; i<_size; i++) {
378 JvmtiTagHashmapEntry* entry = _table[i];
379 JvmtiTagHashmapEntry* prev = NULL;
380 while (entry != NULL) {
381 // obtain the next entry before invoking do_entry - this is
382 // necessary because do_entry may remove the entry from the
383 // hashmap.
384 JvmtiTagHashmapEntry* next = entry->next();
385 closure->do_entry(entry);
386 entry = next;
387 }
388 }
389 }
390
391 // debugging
392 void JvmtiTagHashmap::print_memory_usage() {
393 intptr_t p = (intptr_t)this;
394 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
395
396 // table + entries in KB
397 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
398 entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
399
400 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
401 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
402 entry_count(), hashmap_usage, weak_globals_usage);
403 }
404
405 // compute threshold for the next trace message
406 void JvmtiTagHashmap::compute_next_trace_threshold() {
407 _trace_threshold = entry_count();
408 if (trace_threshold() < medium_trace_threshold) {
409 _trace_threshold += small_trace_threshold;
410 } else {
411 if (trace_threshold() < large_trace_threshold) {
412 _trace_threshold += medium_trace_threshold;
413 } else {
414 _trace_threshold += large_trace_threshold;
415 }
416 }
417 }
418
419 // create a JvmtiTagMap
420 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
421 _env(env),
422 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
423 _free_entries(NULL),
424 _free_entries_count(0)
425 {
426 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
427 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
428
429 _hashmap = new JvmtiTagHashmap();
430
431 // finally add us to the environment
432 ((JvmtiEnvBase *)env)->set_tag_map(this);
433 }
434
435
436 // destroy a JvmtiTagMap
437 JvmtiTagMap::~JvmtiTagMap() {
438
439 // no lock acquired as we assume the enclosing environment is
440 // also being destroryed.
441 ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
442
443 JvmtiTagHashmapEntry** table = _hashmap->table();
444 for (int j = 0; j < _hashmap->size(); j++) {
445 JvmtiTagHashmapEntry* entry = table[j];
446 while (entry != NULL) {
447 JvmtiTagHashmapEntry* next = entry->next();
448 delete entry;
449 entry = next;
450 }
451 }
452
453 // finally destroy the hashmap
454 delete _hashmap;
455 _hashmap = NULL;
456
457 // remove any entries on the free list
458 JvmtiTagHashmapEntry* entry = _free_entries;
459 while (entry != NULL) {
460 JvmtiTagHashmapEntry* next = entry->next();
461 delete entry;
462 entry = next;
463 }
464 _free_entries = NULL;
465 }
466
467 // create a hashmap entry
468 // - if there's an entry on the (per-environment) free list then this
469 // is returned. Otherwise an new entry is allocated.
470 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
471 assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
472 JvmtiTagHashmapEntry* entry;
473 if (_free_entries == NULL) {
474 entry = new JvmtiTagHashmapEntry(ref, tag);
475 } else {
476 assert(_free_entries_count > 0, "mismatched _free_entries_count");
477 _free_entries_count--;
478 entry = _free_entries;
479 _free_entries = entry->next();
480 entry->init(ref, tag);
481 }
482 return entry;
483 }
484
485 // destroy an entry by returning it to the free list
486 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
487 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
488 // limit the size of the free list
489 if (_free_entries_count >= max_free_entries) {
490 delete entry;
491 } else {
492 entry->set_next(_free_entries);
493 _free_entries = entry;
494 _free_entries_count++;
495 }
496 }
497
498 // returns the tag map for the given environments. If the tag map
499 // doesn't exist then it is created.
500 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
501 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
502 if (tag_map == NULL) {
503 MutexLocker mu(JvmtiThreadState_lock);
504 tag_map = ((JvmtiEnvBase*)env)->tag_map();
505 if (tag_map == NULL) {
506 tag_map = new JvmtiTagMap(env);
507 }
508 } else {
509 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
510 }
511 return tag_map;
512 }
513
514 // iterate over all entries in the tag map.
515 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
516 hashmap()->entry_iterate(closure);
517 }
518
519 // returns true if the hashmaps are empty
520 bool JvmtiTagMap::is_empty() {
521 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
522 return hashmap()->entry_count() == 0;
523 }
524
525
526 // Return the tag value for an object, or 0 if the object is
527 // not tagged
528 //
529 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
530 JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
531 if (entry == NULL) {
532 return 0;
533 } else {
534 return entry->tag();
535 }
536 }
537
538
539 // A CallbackWrapper is a support class for querying and tagging an object
540 // around a callback to a profiler. The constructor does pre-callback
541 // work to get the tag value, klass tag value, ... and the destructor
542 // does the post-callback work of tagging or untagging the object.
543 //
544 // {
545 // CallbackWrapper wrapper(tag_map, o);
546 //
547 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
548 //
549 // } // wrapper goes out of scope here which results in the destructor
550 // checking to see if the object has been tagged, untagged, or the
551 // tag value has changed.
552 //
553 class CallbackWrapper : public StackObj {
554 private:
555 JvmtiTagMap* _tag_map;
556 JvmtiTagHashmap* _hashmap;
557 JvmtiTagHashmapEntry* _entry;
558 oop _o;
559 jlong _obj_size;
560 jlong _obj_tag;
561 jlong _klass_tag;
562
563 protected:
564 JvmtiTagMap* tag_map() const { return _tag_map; }
565
566 // invoked post-callback to tag, untag, or update the tag of an object
567 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
568 JvmtiTagHashmapEntry* entry, jlong obj_tag);
569 public:
570 CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
571 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
572 "MT unsafe or must be VM thread");
573
574 // object to tag
575 _o = o;
576
577 // object size
578 _obj_size = (jlong)_o->size() * wordSize;
579
580 // record the context
581 _tag_map = tag_map;
582 _hashmap = tag_map->hashmap();
583 _entry = _hashmap->find(_o);
584
585 // get object tag
586 _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
587
588 // get the class and the class's tag value
589 assert(SystemDictionary::Class_klass()->is_mirror_instance_klass(), "Is not?");
590
591 _klass_tag = tag_for(tag_map, _o->klass()->java_mirror());
592 }
593
594 ~CallbackWrapper() {
595 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
596 }
597
598 inline jlong* obj_tag_p() { return &_obj_tag; }
599 inline jlong obj_size() const { return _obj_size; }
600 inline jlong obj_tag() const { return _obj_tag; }
601 inline jlong klass_tag() const { return _klass_tag; }
602 };
603
604
605
606 // callback post-callback to tag, untag, or update the tag of an object
607 void inline CallbackWrapper::post_callback_tag_update(oop o,
608 JvmtiTagHashmap* hashmap,
609 JvmtiTagHashmapEntry* entry,
610 jlong obj_tag) {
611 if (entry == NULL) {
612 if (obj_tag != 0) {
613 // callback has tagged the object
614 assert(Thread::current()->is_VM_thread(), "must be VMThread");
615 entry = tag_map()->create_entry(o, obj_tag);
616 hashmap->add(o, entry);
617 }
618 } else {
619 // object was previously tagged - the callback may have untagged
620 // the object or changed the tag value
621 if (obj_tag == 0) {
622
623 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
624 assert(entry_removed == entry, "checking");
625 tag_map()->destroy_entry(entry);
626
627 } else {
628 if (obj_tag != entry->tag()) {
629 entry->set_tag(obj_tag);
630 }
631 }
632 }
633 }
634
635 // An extended CallbackWrapper used when reporting an object reference
636 // to the agent.
637 //
638 // {
639 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
640 //
641 // (*callback)(wrapper.klass_tag(),
642 // wrapper.obj_size(),
643 // wrapper.obj_tag_p()
644 // wrapper.referrer_tag_p(), ...)
645 //
646 // } // wrapper goes out of scope here which results in the destructor
647 // checking to see if the referrer object has been tagged, untagged,
648 // or the tag value has changed.
649 //
650 class TwoOopCallbackWrapper : public CallbackWrapper {
651 private:
652 bool _is_reference_to_self;
653 JvmtiTagHashmap* _referrer_hashmap;
654 JvmtiTagHashmapEntry* _referrer_entry;
655 oop _referrer;
656 jlong _referrer_obj_tag;
657 jlong _referrer_klass_tag;
658 jlong* _referrer_tag_p;
659
660 bool is_reference_to_self() const { return _is_reference_to_self; }
661
662 public:
663 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
664 CallbackWrapper(tag_map, o)
665 {
666 // self reference needs to be handled in a special way
667 _is_reference_to_self = (referrer == o);
668
669 if (_is_reference_to_self) {
670 _referrer_klass_tag = klass_tag();
671 _referrer_tag_p = obj_tag_p();
672 } else {
673 _referrer = referrer;
674 // record the context
675 _referrer_hashmap = tag_map->hashmap();
676 _referrer_entry = _referrer_hashmap->find(_referrer);
677
678 // get object tag
679 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
680 _referrer_tag_p = &_referrer_obj_tag;
681
682 // get referrer class tag.
683 _referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror());
684 }
685 }
686
687 ~TwoOopCallbackWrapper() {
688 if (!is_reference_to_self()){
689 post_callback_tag_update(_referrer,
690 _referrer_hashmap,
691 _referrer_entry,
692 _referrer_obj_tag);
693 }
694 }
695
696 // address of referrer tag
697 // (for a self reference this will return the same thing as obj_tag_p())
698 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
699
700 // referrer's class tag
701 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
702 };
703
704 // tag an object
705 //
706 // This function is performance critical. If many threads attempt to tag objects
707 // around the same time then it's possible that the Mutex associated with the
708 // tag map will be a hot lock.
709 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
710 MutexLocker ml(lock());
711
712 // resolve the object
713 oop o = JNIHandles::resolve_non_null(object);
714
715 // see if the object is already tagged
716 JvmtiTagHashmap* hashmap = _hashmap;
717 JvmtiTagHashmapEntry* entry = hashmap->find(o);
718
719 // if the object is not already tagged then we tag it
720 if (entry == NULL) {
721 if (tag != 0) {
722 entry = create_entry(o, tag);
723 hashmap->add(o, entry);
724 } else {
725 // no-op
726 }
727 } else {
728 // if the object is already tagged then we either update
729 // the tag (if a new tag value has been provided)
730 // or remove the object if the new tag value is 0.
731 if (tag == 0) {
732 hashmap->remove(o);
733 destroy_entry(entry);
734 } else {
735 entry->set_tag(tag);
736 }
737 }
738 }
739
740 // get the tag for an object
741 jlong JvmtiTagMap::get_tag(jobject object) {
742 MutexLocker ml(lock());
743
744 // resolve the object
745 oop o = JNIHandles::resolve_non_null(object);
746
747 return tag_for(this, o);
748 }
749
750
751 // Helper class used to describe the static or instance fields of a class.
752 // For each field it holds the field index (as defined by the JVMTI specification),
753 // the field type, and the offset.
754
755 class ClassFieldDescriptor: public CHeapObj<mtInternal> {
756 private:
757 int _field_index;
758 int _field_offset;
759 char _field_type;
760 public:
761 ClassFieldDescriptor(int index, char type, int offset) :
762 _field_index(index), _field_type(type), _field_offset(offset) {
763 }
764 int field_index() const { return _field_index; }
765 char field_type() const { return _field_type; }
766 int field_offset() const { return _field_offset; }
767 };
768
769 class ClassFieldMap: public CHeapObj<mtInternal> {
770 private:
771 enum {
772 initial_field_count = 5
773 };
774
775 // list of field descriptors
776 GrowableArray<ClassFieldDescriptor*>* _fields;
777
778 // constructor
779 ClassFieldMap();
780
781 // add a field
782 void add(int index, char type, int offset);
783
784 // returns the field count for the given class
785 static int compute_field_count(InstanceKlass* ik);
786
787 public:
788 ~ClassFieldMap();
789
790 // access
791 int field_count() { return _fields->length(); }
792 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
793
794 // functions to create maps of static or instance fields
795 static ClassFieldMap* create_map_of_static_fields(Klass* k);
796 static ClassFieldMap* create_map_of_instance_fields(oop obj);
797 };
798
799 ClassFieldMap::ClassFieldMap() {
800 _fields = new (ResourceObj::C_HEAP, mtInternal)
801 GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
802 }
803
804 ClassFieldMap::~ClassFieldMap() {
805 for (int i=0; i<_fields->length(); i++) {
806 delete _fields->at(i);
807 }
808 delete _fields;
809 }
810
811 void ClassFieldMap::add(int index, char type, int offset) {
812 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
813 _fields->append(field);
814 }
815
816 // Returns a heap allocated ClassFieldMap to describe the static fields
817 // of the given class.
818 //
819 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
820 HandleMark hm;
821 InstanceKlass* ik = InstanceKlass::cast(k);
822
823 // create the field map
824 ClassFieldMap* field_map = new ClassFieldMap();
825
826 FilteredFieldStream f(ik, false, false);
827 int max_field_index = f.field_count()-1;
828
829 int index = 0;
830 for (FilteredFieldStream fld(ik, true, true); !fld.eos(); fld.next(), index++) {
831 // ignore instance fields
832 if (!fld.access_flags().is_static()) {
833 continue;
834 }
835 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
836 }
837 return field_map;
838 }
839
840 // Returns a heap allocated ClassFieldMap to describe the instance fields
841 // of the given class. All instance fields are included (this means public
842 // and private fields declared in superclasses and superinterfaces too).
843 //
844 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
845 HandleMark hm;
846 InstanceKlass* ik = InstanceKlass::cast(obj->klass());
847
848 // create the field map
849 ClassFieldMap* field_map = new ClassFieldMap();
850
851 FilteredFieldStream f(ik, false, false);
852
853 int max_field_index = f.field_count()-1;
854
855 int index = 0;
856 for (FilteredFieldStream fld(ik, false, false); !fld.eos(); fld.next(), index++) {
857 // ignore static fields
858 if (fld.access_flags().is_static()) {
859 continue;
860 }
861 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
862 }
863
864 return field_map;
865 }
866
867 // Helper class used to cache a ClassFileMap for the instance fields of
868 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
869 // heap iteration and avoid creating a field map for each object in the heap
870 // (only need to create the map when the first instance of a class is encountered).
871 //
872 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
873 private:
874 enum {
875 initial_class_count = 200
876 };
877 ClassFieldMap* _field_map;
878
879 ClassFieldMap* field_map() const { return _field_map; }
880
881 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
882 ~JvmtiCachedClassFieldMap();
883
884 static GrowableArray<InstanceKlass*>* _class_list;
885 static void add_to_class_list(InstanceKlass* ik);
886
887 public:
888 // returns the field map for a given object (returning map cached
889 // by InstanceKlass if possible
890 static ClassFieldMap* get_map_of_instance_fields(oop obj);
891
892 // removes the field map from all instanceKlasses - should be
893 // called before VM operation completes
894 static void clear_cache();
895
896 // returns the number of ClassFieldMap cached by instanceKlasses
897 static int cached_field_map_count();
898 };
899
900 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
901
902 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
903 _field_map = field_map;
904 }
905
906 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
907 if (_field_map != NULL) {
908 delete _field_map;
909 }
910 }
911
912 // Marker class to ensure that the class file map cache is only used in a defined
913 // scope.
914 class ClassFieldMapCacheMark : public StackObj {
915 private:
916 static bool _is_active;
917 public:
918 ClassFieldMapCacheMark() {
919 assert(Thread::current()->is_VM_thread(), "must be VMThread");
920 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
921 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
922 _is_active = true;
923 }
924 ~ClassFieldMapCacheMark() {
925 JvmtiCachedClassFieldMap::clear_cache();
926 _is_active = false;
927 }
928 static bool is_active() { return _is_active; }
929 };
930
931 bool ClassFieldMapCacheMark::_is_active;
932
933
934 // record that the given InstanceKlass is caching a field map
935 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
936 if (_class_list == NULL) {
937 _class_list = new (ResourceObj::C_HEAP, mtInternal)
938 GrowableArray<InstanceKlass*>(initial_class_count, true);
939 }
940 _class_list->push(ik);
941 }
942
943 // returns the instance field map for the given object
944 // (returns field map cached by the InstanceKlass if possible)
945 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
946 assert(Thread::current()->is_VM_thread(), "must be VMThread");
947 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
948
949 Klass* k = obj->klass();
950 InstanceKlass* ik = InstanceKlass::cast(k);
951
952 // return cached map if possible
953 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
954 if (cached_map != NULL) {
955 assert(cached_map->field_map() != NULL, "missing field list");
956 return cached_map->field_map();
957 } else {
958 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
959 cached_map = new JvmtiCachedClassFieldMap(field_map);
960 ik->set_jvmti_cached_class_field_map(cached_map);
961 add_to_class_list(ik);
962 return field_map;
963 }
964 }
965
966 // remove the fields maps cached from all instanceKlasses
967 void JvmtiCachedClassFieldMap::clear_cache() {
968 assert(Thread::current()->is_VM_thread(), "must be VMThread");
969 if (_class_list != NULL) {
970 for (int i = 0; i < _class_list->length(); i++) {
971 InstanceKlass* ik = _class_list->at(i);
972 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
973 assert(cached_map != NULL, "should not be NULL");
974 ik->set_jvmti_cached_class_field_map(NULL);
975 delete cached_map; // deletes the encapsulated field map
976 }
977 delete _class_list;
978 _class_list = NULL;
979 }
980 }
981
982 // returns the number of ClassFieldMap cached by instanceKlasses
983 int JvmtiCachedClassFieldMap::cached_field_map_count() {
984 return (_class_list == NULL) ? 0 : _class_list->length();
985 }
986
987 // helper function to indicate if an object is filtered by its tag or class tag
988 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
989 jlong klass_tag,
990 int heap_filter) {
991 // apply the heap filter
992 if (obj_tag != 0) {
993 // filter out tagged objects
994 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
995 } else {
996 // filter out untagged objects
997 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
998 }
999 if (klass_tag != 0) {
1000 // filter out objects with tagged classes
1001 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1002 } else {
1003 // filter out objects with untagged classes.
1004 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1005 }
1006 return false;
1007 }
1008
1009 // helper function to indicate if an object is filtered by a klass filter
1010 static inline bool is_filtered_by_klass_filter(oop obj, Klass* klass_filter) {
1011 if (klass_filter != NULL) {
1012 if (obj->klass() != klass_filter) {
1013 return true;
1014 }
1015 }
1016 return false;
1017 }
1018
1019 // helper function to tell if a field is a primitive field or not
1020 static inline bool is_primitive_field_type(char type) {
1021 return (type != 'L' && type != '[');
1022 }
1023
1024 // helper function to copy the value from location addr to jvalue.
1025 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1026 switch (value_type) {
1027 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1028 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
1029 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
1030 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
1031 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
1032 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
1033 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
1034 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
1035 default: ShouldNotReachHere();
1036 }
1037 }
1038
1039 // helper function to invoke string primitive value callback
1040 // returns visit control flags
1041 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1042 CallbackWrapper* wrapper,
1043 oop str,
1044 void* user_data)
1045 {
1046 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1047
1048 typeArrayOop s_value = java_lang_String::value(str);
1049
1050 // JDK-6584008: the value field may be null if a String instance is
1051 // partially constructed.
1052 if (s_value == NULL) {
1053 return 0;
1054 }
1055 // get the string value and length
1056 // (string value may be offset from the base)
1057 int s_len = java_lang_String::length(str);
1058 bool is_latin1 = java_lang_String::is_latin1(str);
1059 jchar* value;
1060 if (s_len > 0) {
1061 if (!is_latin1) {
1062 value = s_value->char_at_addr(0);
1063 } else {
1064 // Inflate latin1 encoded string to UTF16
1065 jchar* buf = NEW_C_HEAP_ARRAY(jchar, s_len, mtInternal);
1066 for (int i = 0; i < s_len; i++) {
1067 buf[i] = ((jchar) s_value->byte_at(i)) & 0xff;
1068 }
1069 value = &buf[0];
1070 }
1071 } else {
1072 // Don't use char_at_addr(0) if length is 0
1073 value = (jchar*) s_value->base(T_CHAR);
1074 }
1075
1076 // invoke the callback
1077 jint res = (*cb)(wrapper->klass_tag(),
1078 wrapper->obj_size(),
1079 wrapper->obj_tag_p(),
1080 value,
1081 (jint)s_len,
1082 user_data);
1083
1084 if (is_latin1 && s_len > 0) {
1085 FREE_C_HEAP_ARRAY(jchar, value);
1086 }
1087 return res;
1088 }
1089
1090 // helper function to invoke string primitive value callback
1091 // returns visit control flags
1092 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1093 CallbackWrapper* wrapper,
1094 oop obj,
1095 void* user_data)
1096 {
1097 assert(obj->is_typeArray(), "not a primitive array");
1098
1099 // get base address of first element
1100 typeArrayOop array = typeArrayOop(obj);
1101 BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
1102 void* elements = array->base(type);
1103
1104 // jvmtiPrimitiveType is defined so this mapping is always correct
1105 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1106
1107 return (*cb)(wrapper->klass_tag(),
1108 wrapper->obj_size(),
1109 wrapper->obj_tag_p(),
1110 (jint)array->length(),
1111 elem_type,
1112 elements,
1113 user_data);
1114 }
1115
1116 // helper function to invoke the primitive field callback for all static fields
1117 // of a given class
1118 static jint invoke_primitive_field_callback_for_static_fields
1119 (CallbackWrapper* wrapper,
1120 oop obj,
1121 jvmtiPrimitiveFieldCallback cb,
1122 void* user_data)
1123 {
1124 // for static fields only the index will be set
1125 static jvmtiHeapReferenceInfo reference_info = { 0 };
1126
1127 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1128 if (java_lang_Class::is_primitive(obj)) {
1129 return 0;
1130 }
1131 Klass* klass = java_lang_Class::as_Klass(obj);
1132
1133 // ignore classes for object and type arrays
1134 if (!klass->is_instance_klass()) {
1135 return 0;
1136 }
1137
1138 // ignore classes which aren't linked yet
1139 InstanceKlass* ik = InstanceKlass::cast(klass);
1140 if (!ik->is_linked()) {
1141 return 0;
1142 }
1143
1144 // get the field map
1145 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1146
1147 // invoke the callback for each static primitive field
1148 for (int i=0; i<field_map->field_count(); i++) {
1149 ClassFieldDescriptor* field = field_map->field_at(i);
1150
1151 // ignore non-primitive fields
1152 char type = field->field_type();
1153 if (!is_primitive_field_type(type)) {
1154 continue;
1155 }
1156 // one-to-one mapping
1157 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1158
1159 // get offset and field value
1160 int offset = field->field_offset();
1161 address addr = (address)klass->java_mirror() + offset;
1162 jvalue value;
1163 copy_to_jvalue(&value, addr, value_type);
1164
1165 // field index
1166 reference_info.field.index = field->field_index();
1167
1168 // invoke the callback
1169 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1170 &reference_info,
1171 wrapper->klass_tag(),
1172 wrapper->obj_tag_p(),
1173 value,
1174 value_type,
1175 user_data);
1176 if (res & JVMTI_VISIT_ABORT) {
1177 delete field_map;
1178 return res;
1179 }
1180 }
1181
1182 delete field_map;
1183 return 0;
1184 }
1185
1186 // helper function to invoke the primitive field callback for all instance fields
1187 // of a given object
1188 static jint invoke_primitive_field_callback_for_instance_fields(
1189 CallbackWrapper* wrapper,
1190 oop obj,
1191 jvmtiPrimitiveFieldCallback cb,
1192 void* user_data)
1193 {
1194 // for instance fields only the index will be set
1195 static jvmtiHeapReferenceInfo reference_info = { 0 };
1196
1197 // get the map of the instance fields
1198 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1199
1200 // invoke the callback for each instance primitive field
1201 for (int i=0; i<fields->field_count(); i++) {
1202 ClassFieldDescriptor* field = fields->field_at(i);
1203
1204 // ignore non-primitive fields
1205 char type = field->field_type();
1206 if (!is_primitive_field_type(type)) {
1207 continue;
1208 }
1209 // one-to-one mapping
1210 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1211
1212 // get offset and field value
1213 int offset = field->field_offset();
1214 address addr = (address)obj + offset;
1215 jvalue value;
1216 copy_to_jvalue(&value, addr, value_type);
1217
1218 // field index
1219 reference_info.field.index = field->field_index();
1220
1221 // invoke the callback
1222 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1223 &reference_info,
1224 wrapper->klass_tag(),
1225 wrapper->obj_tag_p(),
1226 value,
1227 value_type,
1228 user_data);
1229 if (res & JVMTI_VISIT_ABORT) {
1230 return res;
1231 }
1232 }
1233 return 0;
1234 }
1235
1236
1237 // VM operation to iterate over all objects in the heap (both reachable
1238 // and unreachable)
1239 class VM_HeapIterateOperation: public VM_Operation {
1240 private:
1241 ObjectClosure* _blk;
1242 public:
1243 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1244
1245 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1246 void doit() {
1247 // allows class files maps to be cached during iteration
1248 ClassFieldMapCacheMark cm;
1249
1250 // make sure that heap is parsable (fills TLABs with filler objects)
1251 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1252
1253 // Verify heap before iteration - if the heap gets corrupted then
1254 // JVMTI's IterateOverHeap will crash.
1255 if (VerifyBeforeIteration) {
1256 Universe::verify();
1257 }
1258
1259 // do the iteration
1260 // If this operation encounters a bad object when using CMS,
1261 // consider using safe_object_iterate() which avoids perm gen
1262 // objects that may contain bad references.
1263 Universe::heap()->object_iterate(_blk);
1264 }
1265
1266 };
1267
1268
1269 // An ObjectClosure used to support the deprecated IterateOverHeap and
1270 // IterateOverInstancesOfClass functions
1271 class IterateOverHeapObjectClosure: public ObjectClosure {
1272 private:
1273 JvmtiTagMap* _tag_map;
1274 Klass* _klass;
1275 jvmtiHeapObjectFilter _object_filter;
1276 jvmtiHeapObjectCallback _heap_object_callback;
1277 const void* _user_data;
1278
1279 // accessors
1280 JvmtiTagMap* tag_map() const { return _tag_map; }
1281 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1282 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1283 Klass* klass() const { return _klass; }
1284 const void* user_data() const { return _user_data; }
1285
1286 // indicates if iteration has been aborted
1287 bool _iteration_aborted;
1288 bool is_iteration_aborted() const { return _iteration_aborted; }
1289 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1290
1291 public:
1292 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1293 Klass* klass,
1294 jvmtiHeapObjectFilter object_filter,
1295 jvmtiHeapObjectCallback heap_object_callback,
1296 const void* user_data) :
1297 _tag_map(tag_map),
1298 _klass(klass),
1299 _object_filter(object_filter),
1300 _heap_object_callback(heap_object_callback),
1301 _user_data(user_data),
1302 _iteration_aborted(false)
1303 {
1304 }
1305
1306 void do_object(oop o);
1307 };
1308
1309 // invoked for each object in the heap
1310 void IterateOverHeapObjectClosure::do_object(oop o) {
1311 // check if iteration has been halted
1312 if (is_iteration_aborted()) return;
1313
1314 // ignore any objects that aren't visible to profiler
1315 if (!ServiceUtil::visible_oop(o)) return;
1316
1317 // instanceof check when filtering by klass
1318 if (klass() != NULL && !o->is_a(klass())) {
1319 return;
1320 }
1321 // prepare for the calllback
1322 CallbackWrapper wrapper(tag_map(), o);
1323
1324 // if the object is tagged and we're only interested in untagged objects
1325 // then don't invoke the callback. Similiarly, if the object is untagged
1326 // and we're only interested in tagged objects we skip the callback.
1327 if (wrapper.obj_tag() != 0) {
1328 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1329 } else {
1330 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1331 }
1332
1333 // invoke the agent's callback
1334 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1335 wrapper.obj_size(),
1336 wrapper.obj_tag_p(),
1337 (void*)user_data());
1338 if (control == JVMTI_ITERATION_ABORT) {
1339 set_iteration_aborted(true);
1340 }
1341 }
1342
1343 // An ObjectClosure used to support the IterateThroughHeap function
1344 class IterateThroughHeapObjectClosure: public ObjectClosure {
1345 private:
1346 JvmtiTagMap* _tag_map;
1347 Klass* _klass;
1348 int _heap_filter;
1349 const jvmtiHeapCallbacks* _callbacks;
1350 const void* _user_data;
1351
1352 // accessor functions
1353 JvmtiTagMap* tag_map() const { return _tag_map; }
1354 int heap_filter() const { return _heap_filter; }
1355 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1356 Klass* klass() const { return _klass; }
1357 const void* user_data() const { return _user_data; }
1358
1359 // indicates if the iteration has been aborted
1360 bool _iteration_aborted;
1361 bool is_iteration_aborted() const { return _iteration_aborted; }
1362
1363 // used to check the visit control flags. If the abort flag is set
1364 // then we set the iteration aborted flag so that the iteration completes
1365 // without processing any further objects
1366 bool check_flags_for_abort(jint flags) {
1367 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1368 if (is_abort) {
1369 _iteration_aborted = true;
1370 }
1371 return is_abort;
1372 }
1373
1374 public:
1375 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1376 Klass* klass,
1377 int heap_filter,
1378 const jvmtiHeapCallbacks* heap_callbacks,
1379 const void* user_data) :
1380 _tag_map(tag_map),
1381 _klass(klass),
1382 _heap_filter(heap_filter),
1383 _callbacks(heap_callbacks),
1384 _user_data(user_data),
1385 _iteration_aborted(false)
1386 {
1387 }
1388
1389 void do_object(oop o);
1390 };
1391
1392 // invoked for each object in the heap
1393 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1394 // check if iteration has been halted
1395 if (is_iteration_aborted()) return;
1396
1397 // ignore any objects that aren't visible to profiler
1398 if (!ServiceUtil::visible_oop(obj)) return;
1399
1400 // apply class filter
1401 if (is_filtered_by_klass_filter(obj, klass())) return;
1402
1403 // prepare for callback
1404 CallbackWrapper wrapper(tag_map(), obj);
1405
1406 // check if filtered by the heap filter
1407 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1408 return;
1409 }
1410
1411 // for arrays we need the length, otherwise -1
1412 bool is_array = obj->is_array();
1413 int len = is_array ? arrayOop(obj)->length() : -1;
1414
1415 // invoke the object callback (if callback is provided)
1416 if (callbacks()->heap_iteration_callback != NULL) {
1417 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1418 jint res = (*cb)(wrapper.klass_tag(),
1419 wrapper.obj_size(),
1420 wrapper.obj_tag_p(),
1421 (jint)len,
1422 (void*)user_data());
1423 if (check_flags_for_abort(res)) return;
1424 }
1425
1426 // for objects and classes we report primitive fields if callback provided
1427 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1428 jint res;
1429 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1430 if (obj->klass() == SystemDictionary::Class_klass()) {
1431 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1432 obj,
1433 cb,
1434 (void*)user_data());
1435 } else {
1436 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1437 obj,
1438 cb,
1439 (void*)user_data());
1440 }
1441 if (check_flags_for_abort(res)) return;
1442 }
1443
1444 // string callback
1445 if (!is_array &&
1446 callbacks()->string_primitive_value_callback != NULL &&
1447 obj->klass() == SystemDictionary::String_klass()) {
1448 jint res = invoke_string_value_callback(
1449 callbacks()->string_primitive_value_callback,
1450 &wrapper,
1451 obj,
1452 (void*)user_data() );
1453 if (check_flags_for_abort(res)) return;
1454 }
1455
1456 // array callback
1457 if (is_array &&
1458 callbacks()->array_primitive_value_callback != NULL &&
1459 obj->is_typeArray()) {
1460 jint res = invoke_array_primitive_value_callback(
1461 callbacks()->array_primitive_value_callback,
1462 &wrapper,
1463 obj,
1464 (void*)user_data() );
1465 if (check_flags_for_abort(res)) return;
1466 }
1467 };
1468
1469
1470 // Deprecated function to iterate over all objects in the heap
1471 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1472 Klass* klass,
1473 jvmtiHeapObjectCallback heap_object_callback,
1474 const void* user_data)
1475 {
1476 MutexLocker ml(Heap_lock);
1477 IterateOverHeapObjectClosure blk(this,
1478 klass,
1479 object_filter,
1480 heap_object_callback,
1481 user_data);
1482 VM_HeapIterateOperation op(&blk);
1483 VMThread::execute(&op);
1484 }
1485
1486
1487 // Iterates over all objects in the heap
1488 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1489 Klass* klass,
1490 const jvmtiHeapCallbacks* callbacks,
1491 const void* user_data)
1492 {
1493 MutexLocker ml(Heap_lock);
1494 IterateThroughHeapObjectClosure blk(this,
1495 klass,
1496 heap_filter,
1497 callbacks,
1498 user_data);
1499 VM_HeapIterateOperation op(&blk);
1500 VMThread::execute(&op);
1501 }
1502
1503 // support class for get_objects_with_tags
1504
1505 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1506 private:
1507 JvmtiEnv* _env;
1508 jlong* _tags;
1509 jint _tag_count;
1510
1511 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1512 GrowableArray<uint64_t>* _tag_results; // collected tags
1513
1514 public:
1515 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1516 _env = env;
1517 _tags = (jlong*)tags;
1518 _tag_count = tag_count;
1519 _object_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<jobject>(1,true);
1520 _tag_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<uint64_t>(1,true);
1521 }
1522
1523 ~TagObjectCollector() {
1524 delete _object_results;
1525 delete _tag_results;
1526 }
1527
1528 // for each tagged object check if the tag value matches
1529 // - if it matches then we create a JNI local reference to the object
1530 // and record the reference and tag value.
1531 //
1532 void do_entry(JvmtiTagHashmapEntry* entry) {
1533 for (int i=0; i<_tag_count; i++) {
1534 if (_tags[i] == entry->tag()) {
1535 oop o = entry->object();
1536 assert(o != NULL && Universe::heap()->is_in_reserved(o), "sanity check");
1537 #if INCLUDE_ALL_GCS
1538 // The reference in this tag map could be the only (implicitly weak)
1539 // reference to that object. If we hand it out, we need to keep it live wrt
1540 // SATB marking similar to other j.l.ref.Reference referents.
1541 oopDesc::bs()->keep_alive_barrier(o);
1542 #endif
1543 jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1544 _object_results->append(ref);
1545 _tag_results->append((uint64_t)entry->tag());
1546 }
1547 }
1548 }
1549
1550 // return the results from the collection
1551 //
1552 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1553 jvmtiError error;
1554 int count = _object_results->length();
1555 assert(count >= 0, "sanity check");
1556
1557 // if object_result_ptr is not NULL then allocate the result and copy
1558 // in the object references.
1559 if (object_result_ptr != NULL) {
1560 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1561 if (error != JVMTI_ERROR_NONE) {
1562 return error;
1563 }
1564 for (int i=0; i<count; i++) {
1565 (*object_result_ptr)[i] = _object_results->at(i);
1566 }
1567 }
1568
1569 // if tag_result_ptr is not NULL then allocate the result and copy
1570 // in the tag values.
1571 if (tag_result_ptr != NULL) {
1572 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1573 if (error != JVMTI_ERROR_NONE) {
1574 if (object_result_ptr != NULL) {
1575 _env->Deallocate((unsigned char*)object_result_ptr);
1576 }
1577 return error;
1578 }
1579 for (int i=0; i<count; i++) {
1580 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1581 }
1582 }
1583
1584 *count_ptr = count;
1585 return JVMTI_ERROR_NONE;
1586 }
1587 };
1588
1589 // return the list of objects with the specified tags
1590 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1591 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1592
1593 TagObjectCollector collector(env(), tags, count);
1594 {
1595 // iterate over all tagged objects
1596 MutexLocker ml(lock());
1597 entry_iterate(&collector);
1598 }
1599 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1600 }
1601
1602
1603 // ObjectMarker is used to support the marking objects when walking the
1604 // heap.
1605 //
1606 // This implementation uses the existing mark bits in an object for
1607 // marking. Objects that are marked must later have their headers restored.
1608 // As most objects are unlocked and don't have their identity hash computed
1609 // we don't have to save their headers. Instead we save the headers that
1610 // are "interesting". Later when the headers are restored this implementation
1611 // restores all headers to their initial value and then restores the few
1612 // objects that had interesting headers.
1613 //
1614 // Future work: This implementation currently uses growable arrays to save
1615 // the oop and header of interesting objects. As an optimization we could
1616 // use the same technique as the GC and make use of the unused area
1617 // between top() and end().
1618 //
1619
1620 // An ObjectClosure used to restore the mark bits of an object
1621 class RestoreMarksClosure : public ObjectClosure {
1622 public:
1623 void do_object(oop o) {
1624 if (o != NULL) {
1625 markOop mark = o->mark();
1626 if (mark->is_marked()) {
1627 o->init_mark();
1628 }
1629 }
1630 }
1631 };
1632
1633 // ObjectMarker provides the mark and visited functions
1634 class ObjectMarker : AllStatic {
1635 private:
1636 // saved headers
1637 static GrowableArray<oop>* _saved_oop_stack;
1638 static GrowableArray<markOop>* _saved_mark_stack;
1639 static bool _needs_reset; // do we need to reset mark bits?
1640
1641 public:
1642 static void init(); // initialize
1643 static void done(); // clean-up
1644
1645 static inline void mark(oop o); // mark an object
1646 static inline bool visited(oop o); // check if object has been visited
1647
1648 static inline bool needs_reset() { return _needs_reset; }
1649 static inline void set_needs_reset(bool v) { _needs_reset = v; }
1650 };
1651
1652 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1653 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1654 bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default
1655
1656 // initialize ObjectMarker - prepares for object marking
1657 void ObjectMarker::init() {
1658 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1659
1660 // prepare heap for iteration
1661 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1662
1663 // create stacks for interesting headers
1664 _saved_mark_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<markOop>(4000, true);
1665 _saved_oop_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(4000, true);
1666
1667 if (UseBiasedLocking) {
1668 BiasedLocking::preserve_marks();
1669 }
1670 }
1671
1672 // Object marking is done so restore object headers
1673 void ObjectMarker::done() {
1674 // iterate over all objects and restore the mark bits to
1675 // their initial value
1676 RestoreMarksClosure blk;
1677 if (needs_reset()) {
1678 Universe::heap()->object_iterate(&blk);
1679 } else {
1680 // We don't need to reset mark bits on this call, but reset the
1681 // flag to the default for the next call.
1682 set_needs_reset(true);
1683 }
1684
1685 // now restore the interesting headers
1686 for (int i = 0; i < _saved_oop_stack->length(); i++) {
1687 oop o = _saved_oop_stack->at(i);
1688 markOop mark = _saved_mark_stack->at(i);
1689 o->set_mark(mark);
1690 }
1691
1692 if (UseBiasedLocking) {
1693 BiasedLocking::restore_marks();
1694 }
1695
1696 // free the stacks
1697 delete _saved_oop_stack;
1698 delete _saved_mark_stack;
1699 }
1700
1701 // mark an object
1702 inline void ObjectMarker::mark(oop o) {
1703 assert(Universe::heap()->is_in(o), "sanity check");
1704 assert(!o->mark()->is_marked(), "should only mark an object once");
1705
1706 // object's mark word
1707 markOop mark = o->mark();
1708
1709 if (mark->must_be_preserved(o)) {
1710 _saved_mark_stack->push(mark);
1711 _saved_oop_stack->push(o);
1712 }
1713
1714 // mark the object
1715 o->set_mark(markOopDesc::prototype()->set_marked());
1716 }
1717
1718 // return true if object is marked
1719 inline bool ObjectMarker::visited(oop o) {
1720 return o->mark()->is_marked();
1721 }
1722
1723 // Stack allocated class to help ensure that ObjectMarker is used
1724 // correctly. Constructor initializes ObjectMarker, destructor calls
1725 // ObjectMarker's done() function to restore object headers.
1726 class ObjectMarkerController : public StackObj {
1727 public:
1728 ObjectMarkerController() {
1729 ObjectMarker::init();
1730 }
1731 ~ObjectMarkerController() {
1732 ObjectMarker::done();
1733 }
1734 };
1735
1736
1737 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1738 // (not performance critical as only used for roots)
1739 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1740 switch (kind) {
1741 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1742 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1743 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR;
1744 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1745 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1746 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1747 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1748 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1749 }
1750 }
1751
1752 // Base class for all heap walk contexts. The base class maintains a flag
1753 // to indicate if the context is valid or not.
1754 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1755 private:
1756 bool _valid;
1757 public:
1758 HeapWalkContext(bool valid) { _valid = valid; }
1759 void invalidate() { _valid = false; }
1760 bool is_valid() const { return _valid; }
1761 };
1762
1763 // A basic heap walk context for the deprecated heap walking functions.
1764 // The context for a basic heap walk are the callbacks and fields used by
1765 // the referrer caching scheme.
1766 class BasicHeapWalkContext: public HeapWalkContext {
1767 private:
1768 jvmtiHeapRootCallback _heap_root_callback;
1769 jvmtiStackReferenceCallback _stack_ref_callback;
1770 jvmtiObjectReferenceCallback _object_ref_callback;
1771
1772 // used for caching
1773 oop _last_referrer;
1774 jlong _last_referrer_tag;
1775
1776 public:
1777 BasicHeapWalkContext() : HeapWalkContext(false) { }
1778
1779 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1780 jvmtiStackReferenceCallback stack_ref_callback,
1781 jvmtiObjectReferenceCallback object_ref_callback) :
1782 HeapWalkContext(true),
1783 _heap_root_callback(heap_root_callback),
1784 _stack_ref_callback(stack_ref_callback),
1785 _object_ref_callback(object_ref_callback),
1786 _last_referrer(NULL),
1787 _last_referrer_tag(0) {
1788 }
1789
1790 // accessors
1791 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1792 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1793 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1794
1795 oop last_referrer() const { return _last_referrer; }
1796 void set_last_referrer(oop referrer) { _last_referrer = referrer; }
1797 jlong last_referrer_tag() const { return _last_referrer_tag; }
1798 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1799 };
1800
1801 // The advanced heap walk context for the FollowReferences functions.
1802 // The context is the callbacks, and the fields used for filtering.
1803 class AdvancedHeapWalkContext: public HeapWalkContext {
1804 private:
1805 jint _heap_filter;
1806 Klass* _klass_filter;
1807 const jvmtiHeapCallbacks* _heap_callbacks;
1808
1809 public:
1810 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1811
1812 AdvancedHeapWalkContext(jint heap_filter,
1813 Klass* klass_filter,
1814 const jvmtiHeapCallbacks* heap_callbacks) :
1815 HeapWalkContext(true),
1816 _heap_filter(heap_filter),
1817 _klass_filter(klass_filter),
1818 _heap_callbacks(heap_callbacks) {
1819 }
1820
1821 // accessors
1822 jint heap_filter() const { return _heap_filter; }
1823 Klass* klass_filter() const { return _klass_filter; }
1824
1825 const jvmtiHeapReferenceCallback heap_reference_callback() const {
1826 return _heap_callbacks->heap_reference_callback;
1827 };
1828 const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1829 return _heap_callbacks->primitive_field_callback;
1830 }
1831 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1832 return _heap_callbacks->array_primitive_value_callback;
1833 }
1834 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1835 return _heap_callbacks->string_primitive_value_callback;
1836 }
1837 };
1838
1839 // The CallbackInvoker is a class with static functions that the heap walk can call
1840 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1841 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1842 // mode is for the newer FollowReferences function which supports a lot of
1843 // additional callbacks.
1844 class CallbackInvoker : AllStatic {
1845 private:
1846 // heap walk styles
1847 enum { basic, advanced };
1848 static int _heap_walk_type;
1849 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1850 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1851
1852 // context for basic style heap walk
1853 static BasicHeapWalkContext _basic_context;
1854 static BasicHeapWalkContext* basic_context() {
1855 assert(_basic_context.is_valid(), "invalid");
1856 return &_basic_context;
1857 }
1858
1859 // context for advanced style heap walk
1860 static AdvancedHeapWalkContext _advanced_context;
1861 static AdvancedHeapWalkContext* advanced_context() {
1862 assert(_advanced_context.is_valid(), "invalid");
1863 return &_advanced_context;
1864 }
1865
1866 // context needed for all heap walks
1867 static JvmtiTagMap* _tag_map;
1868 static const void* _user_data;
1869 static GrowableArray<oop>* _visit_stack;
1870
1871 // accessors
1872 static JvmtiTagMap* tag_map() { return _tag_map; }
1873 static const void* user_data() { return _user_data; }
1874 static GrowableArray<oop>* visit_stack() { return _visit_stack; }
1875
1876 // if the object hasn't been visited then push it onto the visit stack
1877 // so that it will be visited later
1878 static inline bool check_for_visit(oop obj) {
1879 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1880 return true;
1881 }
1882
1883 // invoke basic style callbacks
1884 static inline bool invoke_basic_heap_root_callback
1885 (jvmtiHeapRootKind root_kind, oop obj);
1886 static inline bool invoke_basic_stack_ref_callback
1887 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1888 int slot, oop obj);
1889 static inline bool invoke_basic_object_reference_callback
1890 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1891
1892 // invoke advanced style callbacks
1893 static inline bool invoke_advanced_heap_root_callback
1894 (jvmtiHeapReferenceKind ref_kind, oop obj);
1895 static inline bool invoke_advanced_stack_ref_callback
1896 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1897 jmethodID method, jlocation bci, jint slot, oop obj);
1898 static inline bool invoke_advanced_object_reference_callback
1899 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1900
1901 // used to report the value of primitive fields
1902 static inline bool report_primitive_field
1903 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1904
1905 public:
1906 // initialize for basic mode
1907 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1908 GrowableArray<oop>* visit_stack,
1909 const void* user_data,
1910 BasicHeapWalkContext context);
1911
1912 // initialize for advanced mode
1913 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1914 GrowableArray<oop>* visit_stack,
1915 const void* user_data,
1916 AdvancedHeapWalkContext context);
1917
1918 // functions to report roots
1919 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
1920 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1921 jmethodID m, oop o);
1922 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1923 jmethodID method, jlocation bci, jint slot, oop o);
1924
1925 // functions to report references
1926 static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
1927 static inline bool report_class_reference(oop referrer, oop referree);
1928 static inline bool report_class_loader_reference(oop referrer, oop referree);
1929 static inline bool report_signers_reference(oop referrer, oop referree);
1930 static inline bool report_protection_domain_reference(oop referrer, oop referree);
1931 static inline bool report_superclass_reference(oop referrer, oop referree);
1932 static inline bool report_interface_reference(oop referrer, oop referree);
1933 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
1934 static inline bool report_field_reference(oop referrer, oop referree, jint slot);
1935 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
1936 static inline bool report_primitive_array_values(oop array);
1937 static inline bool report_string_value(oop str);
1938 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
1939 static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
1940 };
1941
1942 // statics
1943 int CallbackInvoker::_heap_walk_type;
1944 BasicHeapWalkContext CallbackInvoker::_basic_context;
1945 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1946 JvmtiTagMap* CallbackInvoker::_tag_map;
1947 const void* CallbackInvoker::_user_data;
1948 GrowableArray<oop>* CallbackInvoker::_visit_stack;
1949
1950 // initialize for basic heap walk (IterateOverReachableObjects et al)
1951 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1952 GrowableArray<oop>* visit_stack,
1953 const void* user_data,
1954 BasicHeapWalkContext context) {
1955 _tag_map = tag_map;
1956 _visit_stack = visit_stack;
1957 _user_data = user_data;
1958 _basic_context = context;
1959 _advanced_context.invalidate(); // will trigger assertion if used
1960 _heap_walk_type = basic;
1961 }
1962
1963 // initialize for advanced heap walk (FollowReferences)
1964 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1965 GrowableArray<oop>* visit_stack,
1966 const void* user_data,
1967 AdvancedHeapWalkContext context) {
1968 _tag_map = tag_map;
1969 _visit_stack = visit_stack;
1970 _user_data = user_data;
1971 _advanced_context = context;
1972 _basic_context.invalidate(); // will trigger assertion if used
1973 _heap_walk_type = advanced;
1974 }
1975
1976
1977 // invoke basic style heap root callback
1978 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
1979 assert(ServiceUtil::visible_oop(obj), "checking");
1980
1981 // if we heap roots should be reported
1982 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1983 if (cb == NULL) {
1984 return check_for_visit(obj);
1985 }
1986
1987 CallbackWrapper wrapper(tag_map(), obj);
1988 jvmtiIterationControl control = (*cb)(root_kind,
1989 wrapper.klass_tag(),
1990 wrapper.obj_size(),
1991 wrapper.obj_tag_p(),
1992 (void*)user_data());
1993 // push root to visit stack when following references
1994 if (control == JVMTI_ITERATION_CONTINUE &&
1995 basic_context()->object_ref_callback() != NULL) {
1996 visit_stack()->push(obj);
1997 }
1998 return control != JVMTI_ITERATION_ABORT;
1999 }
2000
2001 // invoke basic style stack ref callback
2002 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
2003 jlong thread_tag,
2004 jint depth,
2005 jmethodID method,
2006 jint slot,
2007 oop obj) {
2008 assert(ServiceUtil::visible_oop(obj), "checking");
2009
2010 // if we stack refs should be reported
2011 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
2012 if (cb == NULL) {
2013 return check_for_visit(obj);
2014 }
2015
2016 CallbackWrapper wrapper(tag_map(), obj);
2017 jvmtiIterationControl control = (*cb)(root_kind,
2018 wrapper.klass_tag(),
2019 wrapper.obj_size(),
2020 wrapper.obj_tag_p(),
2021 thread_tag,
2022 depth,
2023 method,
2024 slot,
2025 (void*)user_data());
2026 // push root to visit stack when following references
2027 if (control == JVMTI_ITERATION_CONTINUE &&
2028 basic_context()->object_ref_callback() != NULL) {
2029 visit_stack()->push(obj);
2030 }
2031 return control != JVMTI_ITERATION_ABORT;
2032 }
2033
2034 // invoke basic style object reference callback
2035 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2036 oop referrer,
2037 oop referree,
2038 jint index) {
2039
2040 assert(ServiceUtil::visible_oop(referrer), "checking");
2041 assert(ServiceUtil::visible_oop(referree), "checking");
2042
2043 BasicHeapWalkContext* context = basic_context();
2044
2045 // callback requires the referrer's tag. If it's the same referrer
2046 // as the last call then we use the cached value.
2047 jlong referrer_tag;
2048 if (referrer == context->last_referrer()) {
2049 referrer_tag = context->last_referrer_tag();
2050 } else {
2051 referrer_tag = tag_for(tag_map(), referrer);
2052 }
2053
2054 // do the callback
2055 CallbackWrapper wrapper(tag_map(), referree);
2056 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2057 jvmtiIterationControl control = (*cb)(ref_kind,
2058 wrapper.klass_tag(),
2059 wrapper.obj_size(),
2060 wrapper.obj_tag_p(),
2061 referrer_tag,
2062 index,
2063 (void*)user_data());
2064
2065 // record referrer and referrer tag. For self-references record the
2066 // tag value from the callback as this might differ from referrer_tag.
2067 context->set_last_referrer(referrer);
2068 if (referrer == referree) {
2069 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2070 } else {
2071 context->set_last_referrer_tag(referrer_tag);
2072 }
2073
2074 if (control == JVMTI_ITERATION_CONTINUE) {
2075 return check_for_visit(referree);
2076 } else {
2077 return control != JVMTI_ITERATION_ABORT;
2078 }
2079 }
2080
2081 // invoke advanced style heap root callback
2082 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2083 oop obj) {
2084 assert(ServiceUtil::visible_oop(obj), "checking");
2085
2086 AdvancedHeapWalkContext* context = advanced_context();
2087
2088 // check that callback is provided
2089 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2090 if (cb == NULL) {
2091 return check_for_visit(obj);
2092 }
2093
2094 // apply class filter
2095 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2096 return check_for_visit(obj);
2097 }
2098
2099 // setup the callback wrapper
2100 CallbackWrapper wrapper(tag_map(), obj);
2101
2102 // apply tag filter
2103 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2104 wrapper.klass_tag(),
2105 context->heap_filter())) {
2106 return check_for_visit(obj);
2107 }
2108
2109 // for arrays we need the length, otherwise -1
2110 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2111
2112 // invoke the callback
2113 jint res = (*cb)(ref_kind,
2114 NULL, // referrer info
2115 wrapper.klass_tag(),
2116 0, // referrer_class_tag is 0 for heap root
2117 wrapper.obj_size(),
2118 wrapper.obj_tag_p(),
2119 NULL, // referrer_tag_p
2120 len,
2121 (void*)user_data());
2122 if (res & JVMTI_VISIT_ABORT) {
2123 return false;// referrer class tag
2124 }
2125 if (res & JVMTI_VISIT_OBJECTS) {
2126 check_for_visit(obj);
2127 }
2128 return true;
2129 }
2130
2131 // report a reference from a thread stack to an object
2132 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2133 jlong thread_tag,
2134 jlong tid,
2135 int depth,
2136 jmethodID method,
2137 jlocation bci,
2138 jint slot,
2139 oop obj) {
2140 assert(ServiceUtil::visible_oop(obj), "checking");
2141
2142 AdvancedHeapWalkContext* context = advanced_context();
2143
2144 // check that callback is provider
2145 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2146 if (cb == NULL) {
2147 return check_for_visit(obj);
2148 }
2149
2150 // apply class filter
2151 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2152 return check_for_visit(obj);
2153 }
2154
2155 // setup the callback wrapper
2156 CallbackWrapper wrapper(tag_map(), obj);
2157
2158 // apply tag filter
2159 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2160 wrapper.klass_tag(),
2161 context->heap_filter())) {
2162 return check_for_visit(obj);
2163 }
2164
2165 // setup the referrer info
2166 jvmtiHeapReferenceInfo reference_info;
2167 reference_info.stack_local.thread_tag = thread_tag;
2168 reference_info.stack_local.thread_id = tid;
2169 reference_info.stack_local.depth = depth;
2170 reference_info.stack_local.method = method;
2171 reference_info.stack_local.location = bci;
2172 reference_info.stack_local.slot = slot;
2173
2174 // for arrays we need the length, otherwise -1
2175 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2176
2177 // call into the agent
2178 int res = (*cb)(ref_kind,
2179 &reference_info,
2180 wrapper.klass_tag(),
2181 0, // referrer_class_tag is 0 for heap root (stack)
2182 wrapper.obj_size(),
2183 wrapper.obj_tag_p(),
2184 NULL, // referrer_tag is 0 for root
2185 len,
2186 (void*)user_data());
2187
2188 if (res & JVMTI_VISIT_ABORT) {
2189 return false;
2190 }
2191 if (res & JVMTI_VISIT_OBJECTS) {
2192 check_for_visit(obj);
2193 }
2194 return true;
2195 }
2196
2197 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2198 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2199 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2200 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2201 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2202 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2203 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2204 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2205
2206 // invoke the object reference callback to report a reference
2207 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2208 oop referrer,
2209 oop obj,
2210 jint index)
2211 {
2212 // field index is only valid field in reference_info
2213 static jvmtiHeapReferenceInfo reference_info = { 0 };
2214
2215 assert(ServiceUtil::visible_oop(referrer), "checking");
2216 assert(ServiceUtil::visible_oop(obj), "checking");
2217
2218 AdvancedHeapWalkContext* context = advanced_context();
2219
2220 // check that callback is provider
2221 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2222 if (cb == NULL) {
2223 return check_for_visit(obj);
2224 }
2225
2226 // apply class filter
2227 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2228 return check_for_visit(obj);
2229 }
2230
2231 // setup the callback wrapper
2232 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2233
2234 // apply tag filter
2235 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2236 wrapper.klass_tag(),
2237 context->heap_filter())) {
2238 return check_for_visit(obj);
2239 }
2240
2241 // field index is only valid field in reference_info
2242 reference_info.field.index = index;
2243
2244 // for arrays we need the length, otherwise -1
2245 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2246
2247 // invoke the callback
2248 int res = (*cb)(ref_kind,
2249 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2250 wrapper.klass_tag(),
2251 wrapper.referrer_klass_tag(),
2252 wrapper.obj_size(),
2253 wrapper.obj_tag_p(),
2254 wrapper.referrer_tag_p(),
2255 len,
2256 (void*)user_data());
2257
2258 if (res & JVMTI_VISIT_ABORT) {
2259 return false;
2260 }
2261 if (res & JVMTI_VISIT_OBJECTS) {
2262 check_for_visit(obj);
2263 }
2264 return true;
2265 }
2266
2267 // report a "simple root"
2268 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2269 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2270 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2271 assert(ServiceUtil::visible_oop(obj), "checking");
2272
2273 if (is_basic_heap_walk()) {
2274 // map to old style root kind
2275 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2276 return invoke_basic_heap_root_callback(root_kind, obj);
2277 } else {
2278 assert(is_advanced_heap_walk(), "wrong heap walk type");
2279 return invoke_advanced_heap_root_callback(kind, obj);
2280 }
2281 }
2282
2283
2284 // invoke the primitive array values
2285 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2286 assert(obj->is_typeArray(), "not a primitive array");
2287
2288 AdvancedHeapWalkContext* context = advanced_context();
2289 assert(context->array_primitive_value_callback() != NULL, "no callback");
2290
2291 // apply class filter
2292 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2293 return true;
2294 }
2295
2296 CallbackWrapper wrapper(tag_map(), obj);
2297
2298 // apply tag filter
2299 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2300 wrapper.klass_tag(),
2301 context->heap_filter())) {
2302 return true;
2303 }
2304
2305 // invoke the callback
2306 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2307 &wrapper,
2308 obj,
2309 (void*)user_data());
2310 return (!(res & JVMTI_VISIT_ABORT));
2311 }
2312
2313 // invoke the string value callback
2314 inline bool CallbackInvoker::report_string_value(oop str) {
2315 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2316
2317 AdvancedHeapWalkContext* context = advanced_context();
2318 assert(context->string_primitive_value_callback() != NULL, "no callback");
2319
2320 // apply class filter
2321 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2322 return true;
2323 }
2324
2325 CallbackWrapper wrapper(tag_map(), str);
2326
2327 // apply tag filter
2328 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2329 wrapper.klass_tag(),
2330 context->heap_filter())) {
2331 return true;
2332 }
2333
2334 // invoke the callback
2335 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2336 &wrapper,
2337 str,
2338 (void*)user_data());
2339 return (!(res & JVMTI_VISIT_ABORT));
2340 }
2341
2342 // invoke the primitive field callback
2343 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2344 oop obj,
2345 jint index,
2346 address addr,
2347 char type)
2348 {
2349 // for primitive fields only the index will be set
2350 static jvmtiHeapReferenceInfo reference_info = { 0 };
2351
2352 AdvancedHeapWalkContext* context = advanced_context();
2353 assert(context->primitive_field_callback() != NULL, "no callback");
2354
2355 // apply class filter
2356 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2357 return true;
2358 }
2359
2360 CallbackWrapper wrapper(tag_map(), obj);
2361
2362 // apply tag filter
2363 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2364 wrapper.klass_tag(),
2365 context->heap_filter())) {
2366 return true;
2367 }
2368
2369 // the field index in the referrer
2370 reference_info.field.index = index;
2371
2372 // map the type
2373 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2374
2375 // setup the jvalue
2376 jvalue value;
2377 copy_to_jvalue(&value, addr, value_type);
2378
2379 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2380 int res = (*cb)(ref_kind,
2381 &reference_info,
2382 wrapper.klass_tag(),
2383 wrapper.obj_tag_p(),
2384 value,
2385 value_type,
2386 (void*)user_data());
2387 return (!(res & JVMTI_VISIT_ABORT));
2388 }
2389
2390
2391 // instance field
2392 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2393 jint index,
2394 address value,
2395 char type) {
2396 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2397 obj,
2398 index,
2399 value,
2400 type);
2401 }
2402
2403 // static field
2404 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2405 jint index,
2406 address value,
2407 char type) {
2408 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2409 obj,
2410 index,
2411 value,
2412 type);
2413 }
2414
2415 // report a JNI local (root object) to the profiler
2416 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2417 if (is_basic_heap_walk()) {
2418 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2419 thread_tag,
2420 depth,
2421 m,
2422 -1,
2423 obj);
2424 } else {
2425 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2426 thread_tag, tid,
2427 depth,
2428 m,
2429 (jlocation)-1,
2430 -1,
2431 obj);
2432 }
2433 }
2434
2435
2436 // report a local (stack reference, root object)
2437 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2438 jlong tid,
2439 jint depth,
2440 jmethodID method,
2441 jlocation bci,
2442 jint slot,
2443 oop obj) {
2444 if (is_basic_heap_walk()) {
2445 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2446 thread_tag,
2447 depth,
2448 method,
2449 slot,
2450 obj);
2451 } else {
2452 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2453 thread_tag,
2454 tid,
2455 depth,
2456 method,
2457 bci,
2458 slot,
2459 obj);
2460 }
2461 }
2462
2463 // report an object referencing a class.
2464 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2465 if (is_basic_heap_walk()) {
2466 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2467 } else {
2468 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2469 }
2470 }
2471
2472 // report a class referencing its class loader.
2473 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2474 if (is_basic_heap_walk()) {
2475 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2476 } else {
2477 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2478 }
2479 }
2480
2481 // report a class referencing its signers.
2482 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2483 if (is_basic_heap_walk()) {
2484 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2485 } else {
2486 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2487 }
2488 }
2489
2490 // report a class referencing its protection domain..
2491 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2492 if (is_basic_heap_walk()) {
2493 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2494 } else {
2495 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2496 }
2497 }
2498
2499 // report a class referencing its superclass.
2500 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2501 if (is_basic_heap_walk()) {
2502 // Send this to be consistent with past implementation
2503 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2504 } else {
2505 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2506 }
2507 }
2508
2509 // report a class referencing one of its interfaces.
2510 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2511 if (is_basic_heap_walk()) {
2512 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2513 } else {
2514 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2515 }
2516 }
2517
2518 // report a class referencing one of its static fields.
2519 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2520 if (is_basic_heap_walk()) {
2521 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2522 } else {
2523 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2524 }
2525 }
2526
2527 // report an array referencing an element object
2528 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2529 if (is_basic_heap_walk()) {
2530 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2531 } else {
2532 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2533 }
2534 }
2535
2536 // report an object referencing an instance field object
2537 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2538 if (is_basic_heap_walk()) {
2539 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2540 } else {
2541 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2542 }
2543 }
2544
2545 // report an array referencing an element object
2546 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2547 if (is_basic_heap_walk()) {
2548 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2549 } else {
2550 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2551 }
2552 }
2553
2554 // A supporting closure used to process simple roots
2555 class SimpleRootsClosure : public OopClosure {
2556 private:
2557 jvmtiHeapReferenceKind _kind;
2558 bool _continue;
2559
2560 jvmtiHeapReferenceKind root_kind() { return _kind; }
2561
2562 public:
2563 void set_kind(jvmtiHeapReferenceKind kind) {
2564 _kind = kind;
2565 _continue = true;
2566 }
2567
2568 inline bool stopped() {
2569 return !_continue;
2570 }
2571
2572 void do_oop(oop* obj_p) {
2573 // iteration has terminated
2574 if (stopped()) {
2575 return;
2576 }
2577
2578 // ignore null or deleted handles
2579 oop o = *obj_p;
2580 if (o == NULL || oopDesc::equals(o, JNIHandles::deleted_handle())) {
2581 return;
2582 }
2583
2584 assert(Universe::heap()->is_in_reserved(o), "should be impossible");
2585
2586 jvmtiHeapReferenceKind kind = root_kind();
2587 if (kind == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2588 // SystemDictionary::always_strong_oops_do reports the application
2589 // class loader as a root. We want this root to be reported as
2590 // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2591 if (!o->is_instance() || !InstanceKlass::cast(o->klass())->is_mirror_instance_klass()) {
2592 kind = JVMTI_HEAP_REFERENCE_OTHER;
2593 }
2594 }
2595
2596 // some objects are ignored - in the case of simple
2597 // roots it's mostly Symbol*s that we are skipping
2598 // here.
2599 if (!ServiceUtil::visible_oop(o)) {
2600 return;
2601 }
2602
2603 // invoke the callback
2604 _continue = CallbackInvoker::report_simple_root(kind, o);
2605
2606 }
2607 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2608 };
2609
2610 // A supporting closure used to process JNI locals
2611 class JNILocalRootsClosure : public OopClosure {
2612 private:
2613 jlong _thread_tag;
2614 jlong _tid;
2615 jint _depth;
2616 jmethodID _method;
2617 bool _continue;
2618 public:
2619 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2620 _thread_tag = thread_tag;
2621 _tid = tid;
2622 _depth = depth;
2623 _method = method;
2624 _continue = true;
2625 }
2626
2627 inline bool stopped() {
2628 return !_continue;
2629 }
2630
2631 void do_oop(oop* obj_p) {
2632 // iteration has terminated
2633 if (stopped()) {
2634 return;
2635 }
2636
2637 // ignore null or deleted handles
2638 oop o = *obj_p;
2639 if (o == NULL || oopDesc::equals(o, JNIHandles::deleted_handle())) {
2640 return;
2641 }
2642
2643 if (!ServiceUtil::visible_oop(o)) {
2644 return;
2645 }
2646
2647 // invoke the callback
2648 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2649 }
2650 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2651 };
2652
2653
2654 // A VM operation to iterate over objects that are reachable from
2655 // a set of roots or an initial object.
2656 //
2657 // For VM_HeapWalkOperation the set of roots used is :-
2658 //
2659 // - All JNI global references
2660 // - All inflated monitors
2661 // - All classes loaded by the boot class loader (or all classes
2662 // in the event that class unloading is disabled)
2663 // - All java threads
2664 // - For each java thread then all locals and JNI local references
2665 // on the thread's execution stack
2666 // - All visible/explainable objects from Universes::oops_do
2667 //
2668 class VM_HeapWalkOperation: public VM_Operation {
2669 private:
2670 enum {
2671 initial_visit_stack_size = 4000
2672 };
2673
2674 bool _is_advanced_heap_walk; // indicates FollowReferences
2675 JvmtiTagMap* _tag_map;
2676 Handle _initial_object;
2677 GrowableArray<oop>* _visit_stack; // the visit stack
2678
2679 bool _collecting_heap_roots; // are we collecting roots
2680 bool _following_object_refs; // are we following object references
2681
2682 bool _reporting_primitive_fields; // optional reporting
2683 bool _reporting_primitive_array_values;
2684 bool _reporting_string_values;
2685
2686 GrowableArray<oop>* create_visit_stack() {
2687 return new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(initial_visit_stack_size, true);
2688 }
2689
2690 // accessors
2691 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2692 JvmtiTagMap* tag_map() const { return _tag_map; }
2693 Handle initial_object() const { return _initial_object; }
2694
2695 bool is_following_references() const { return _following_object_refs; }
2696
2697 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2698 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2699 bool is_reporting_string_values() const { return _reporting_string_values; }
2700
2701 GrowableArray<oop>* visit_stack() const { return _visit_stack; }
2702
2703 // iterate over the various object types
2704 inline bool iterate_over_array(oop o);
2705 inline bool iterate_over_type_array(oop o);
2706 inline bool iterate_over_class(oop o);
2707 inline bool iterate_over_object(oop o);
2708
2709 // root collection
2710 inline bool collect_simple_roots();
2711 inline bool collect_stack_roots();
2712 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2713
2714 // visit an object
2715 inline bool visit(oop o);
2716
2717 public:
2718 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2719 Handle initial_object,
2720 BasicHeapWalkContext callbacks,
2721 const void* user_data);
2722
2723 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2724 Handle initial_object,
2725 AdvancedHeapWalkContext callbacks,
2726 const void* user_data);
2727
2728 ~VM_HeapWalkOperation();
2729
2730 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2731 void doit();
2732 };
2733
2734
2735 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2736 Handle initial_object,
2737 BasicHeapWalkContext callbacks,
2738 const void* user_data) {
2739 _is_advanced_heap_walk = false;
2740 _tag_map = tag_map;
2741 _initial_object = initial_object;
2742 _following_object_refs = (callbacks.object_ref_callback() != NULL);
2743 _reporting_primitive_fields = false;
2744 _reporting_primitive_array_values = false;
2745 _reporting_string_values = false;
2746 _visit_stack = create_visit_stack();
2747
2748
2749 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2750 }
2751
2752 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2753 Handle initial_object,
2754 AdvancedHeapWalkContext callbacks,
2755 const void* user_data) {
2756 _is_advanced_heap_walk = true;
2757 _tag_map = tag_map;
2758 _initial_object = initial_object;
2759 _following_object_refs = true;
2760 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2761 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2762 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2763 _visit_stack = create_visit_stack();
2764
2765 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2766 }
2767
2768 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2769 if (_following_object_refs) {
2770 assert(_visit_stack != NULL, "checking");
2771 delete _visit_stack;
2772 _visit_stack = NULL;
2773 }
2774 }
2775
2776 // an array references its class and has a reference to
2777 // each element in the array
2778 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2779 objArrayOop array = objArrayOop(o);
2780
2781 // array reference to its class
2782 oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
2783 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2784 return false;
2785 }
2786
2787 // iterate over the array and report each reference to a
2788 // non-null element
2789 for (int index=0; index<array->length(); index++) {
2790 oop elem = array->obj_at(index);
2791 if (elem == NULL) {
2792 continue;
2793 }
2794
2795 // report the array reference o[index] = elem
2796 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2797 return false;
2798 }
2799 }
2800 return true;
2801 }
2802
2803 // a type array references its class
2804 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2805 Klass* k = o->klass();
2806 oop mirror = k->java_mirror();
2807 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2808 return false;
2809 }
2810
2811 // report the array contents if required
2812 if (is_reporting_primitive_array_values()) {
2813 if (!CallbackInvoker::report_primitive_array_values(o)) {
2814 return false;
2815 }
2816 }
2817 return true;
2818 }
2819
2820 #ifdef ASSERT
2821 // verify that a static oop field is in range
2822 static inline bool verify_static_oop(InstanceKlass* ik,
2823 oop mirror, int offset) {
2824 address obj_p = (address)mirror + offset;
2825 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2826 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2827 assert(end >= start, "sanity check");
2828
2829 if (obj_p >= start && obj_p < end) {
2830 return true;
2831 } else {
2832 return false;
2833 }
2834 }
2835 #endif // #ifdef ASSERT
2836
2837 // a class references its super class, interfaces, class loader, ...
2838 // and finally its static fields
2839 inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) {
2840 int i;
2841 Klass* klass = java_lang_Class::as_Klass(java_class);
2842
2843 if (klass->is_instance_klass()) {
2844 InstanceKlass* ik = InstanceKlass::cast(klass);
2845
2846 // Ignore the class if it hasn't been initialized yet
2847 if (!ik->is_linked()) {
2848 return true;
2849 }
2850
2851 // get the java mirror
2852 oop mirror = klass->java_mirror();
2853
2854 // super (only if something more interesting than java.lang.Object)
2855 Klass* java_super = ik->java_super();
2856 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2857 oop super = java_super->java_mirror();
2858 if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2859 return false;
2860 }
2861 }
2862
2863 // class loader
2864 oop cl = ik->class_loader();
2865 if (cl != NULL) {
2866 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2867 return false;
2868 }
2869 }
2870
2871 // protection domain
2872 oop pd = ik->protection_domain();
2873 if (pd != NULL) {
2874 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2875 return false;
2876 }
2877 }
2878
2879 // signers
2880 oop signers = ik->signers();
2881 if (signers != NULL) {
2882 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2883 return false;
2884 }
2885 }
2886
2887 // references from the constant pool
2888 {
2889 ConstantPool* pool = ik->constants();
2890 for (int i = 1; i < pool->length(); i++) {
2891 constantTag tag = pool->tag_at(i).value();
2892 if (tag.is_string() || tag.is_klass()) {
2893 oop entry;
2894 if (tag.is_string()) {
2895 entry = pool->resolved_string_at(i);
2896 // If the entry is non-null it is resolved.
2897 if (entry == NULL) continue;
2898 } else {
2899 entry = pool->resolved_klass_at(i)->java_mirror();
2900 }
2901 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2902 return false;
2903 }
2904 }
2905 }
2906 }
2907
2908 // interfaces
2909 // (These will already have been reported as references from the constant pool
2910 // but are specified by IterateOverReachableObjects and must be reported).
2911 Array<Klass*>* interfaces = ik->local_interfaces();
2912 for (i = 0; i < interfaces->length(); i++) {
2913 oop interf = ((Klass*)interfaces->at(i))->java_mirror();
2914 if (interf == NULL) {
2915 continue;
2916 }
2917 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
2918 return false;
2919 }
2920 }
2921
2922 // iterate over the static fields
2923
2924 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
2925 for (i=0; i<field_map->field_count(); i++) {
2926 ClassFieldDescriptor* field = field_map->field_at(i);
2927 char type = field->field_type();
2928 if (!is_primitive_field_type(type)) {
2929 oop fld_o = mirror->obj_field(field->field_offset());
2930 assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check");
2931 if (fld_o != NULL) {
2932 int slot = field->field_index();
2933 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
2934 delete field_map;
2935 return false;
2936 }
2937 }
2938 } else {
2939 if (is_reporting_primitive_fields()) {
2940 address addr = (address)mirror + field->field_offset();
2941 int slot = field->field_index();
2942 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
2943 delete field_map;
2944 return false;
2945 }
2946 }
2947 }
2948 }
2949 delete field_map;
2950
2951 return true;
2952 }
2953
2954 return true;
2955 }
2956
2957 // an object references a class and its instance fields
2958 // (static fields are ignored here as we report these as
2959 // references from the class).
2960 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
2961 // reference to the class
2962 if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) {
2963 return false;
2964 }
2965
2966 // iterate over instance fields
2967 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
2968 for (int i=0; i<field_map->field_count(); i++) {
2969 ClassFieldDescriptor* field = field_map->field_at(i);
2970 char type = field->field_type();
2971 if (!is_primitive_field_type(type)) {
2972 oop fld_o = o->obj_field(field->field_offset());
2973 // ignore any objects that aren't visible to profiler
2974 if (fld_o != NULL && ServiceUtil::visible_oop(fld_o)) {
2975 assert(Universe::heap()->is_in_reserved(fld_o), "unsafe code should not "
2976 "have references to Klass* anymore");
2977 int slot = field->field_index();
2978 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
2979 return false;
2980 }
2981 }
2982 } else {
2983 if (is_reporting_primitive_fields()) {
2984 // primitive instance field
2985 address addr = (address)o + field->field_offset();
2986 int slot = field->field_index();
2987 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
2988 return false;
2989 }
2990 }
2991 }
2992 }
2993
2994 // if the object is a java.lang.String
2995 if (is_reporting_string_values() &&
2996 o->klass() == SystemDictionary::String_klass()) {
2997 if (!CallbackInvoker::report_string_value(o)) {
2998 return false;
2999 }
3000 }
3001 return true;
3002 }
3003
3004
3005 // Collects all simple (non-stack) roots except for threads;
3006 // threads are handled in collect_stack_roots() as an optimization.
3007 // if there's a heap root callback provided then the callback is
3008 // invoked for each simple root.
3009 // if an object reference callback is provided then all simple
3010 // roots are pushed onto the marking stack so that they can be
3011 // processed later
3012 //
3013 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3014 SimpleRootsClosure blk;
3015
3016 // JNI globals
3017 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3018 JNIHandles::oops_do(&blk);
3019 if (blk.stopped()) {
3020 return false;
3021 }
3022
3023 // Preloaded classes and loader from the system dictionary
3024 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3025 SystemDictionary::always_strong_oops_do(&blk);
3026 KlassToOopClosure klass_blk(&blk);
3027 ClassLoaderDataGraph::always_strong_oops_do(&blk, &klass_blk, false);
3028 if (blk.stopped()) {
3029 return false;
3030 }
3031
3032 // Inflated monitors
3033 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3034 ObjectSynchronizer::oops_do(&blk);
3035 if (blk.stopped()) {
3036 return false;
3037 }
3038
3039 // threads are now handled in collect_stack_roots()
3040
3041 // Other kinds of roots maintained by HotSpot
3042 // Many of these won't be visible but others (such as instances of important
3043 // exceptions) will be visible.
3044 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3045 Universe::oops_do(&blk);
3046
3047 // If there are any non-perm roots in the code cache, visit them.
3048 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3049 CodeBlobToOopClosure look_in_blobs(&blk, !CodeBlobToOopClosure::FixRelocations);
3050 CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3051
3052 return true;
3053 }
3054
3055 // Walk the stack of a given thread and find all references (locals
3056 // and JNI calls) and report these as stack references
3057 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3058 JNILocalRootsClosure* blk)
3059 {
3060 oop threadObj = java_thread->threadObj();
3061 assert(threadObj != NULL, "sanity check");
3062
3063 // only need to get the thread's tag once per thread
3064 jlong thread_tag = tag_for(_tag_map, threadObj);
3065
3066 // also need the thread id
3067 jlong tid = java_lang_Thread::thread_id(threadObj);
3068
3069
3070 if (java_thread->has_last_Java_frame()) {
3071
3072 // vframes are resource allocated
3073 Thread* current_thread = Thread::current();
3074 ResourceMark rm(current_thread);
3075 HandleMark hm(current_thread);
3076
3077 RegisterMap reg_map(java_thread);
3078 frame f = java_thread->last_frame();
3079 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3080
3081 bool is_top_frame = true;
3082 int depth = 0;
3083 frame* last_entry_frame = NULL;
3084
3085 while (vf != NULL) {
3086 if (vf->is_java_frame()) {
3087
3088 // java frame (interpreted, compiled, ...)
3089 javaVFrame *jvf = javaVFrame::cast(vf);
3090
3091 // the jmethodID
3092 jmethodID method = jvf->method()->jmethod_id();
3093
3094 if (!(jvf->method()->is_native())) {
3095 jlocation bci = (jlocation)jvf->bci();
3096 StackValueCollection* locals = jvf->locals();
3097 for (int slot=0; slot<locals->size(); slot++) {
3098 if (locals->at(slot)->type() == T_OBJECT) {
3099 oop o = locals->obj_at(slot)();
3100 if (o == NULL) {
3101 continue;
3102 }
3103
3104 // stack reference
3105 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3106 bci, slot, o)) {
3107 return false;
3108 }
3109 }
3110 }
3111
3112 StackValueCollection* exprs = jvf->expressions();
3113 for (int index=0; index < exprs->size(); index++) {
3114 if (exprs->at(index)->type() == T_OBJECT) {
3115 oop o = exprs->obj_at(index)();
3116 if (o == NULL) {
3117 continue;
3118 }
3119
3120 // stack reference
3121 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3122 bci, locals->size() + index, o)) {
3123 return false;
3124 }
3125 }
3126 }
3127
3128 // Follow oops from compiled nmethod
3129 if (jvf->cb() != NULL && jvf->cb()->is_nmethod()) {
3130 blk->set_context(thread_tag, tid, depth, method);
3131 jvf->cb()->as_nmethod()->oops_do(blk);
3132 }
3133 } else {
3134 blk->set_context(thread_tag, tid, depth, method);
3135 if (is_top_frame) {
3136 // JNI locals for the top frame.
3137 java_thread->active_handles()->oops_do(blk);
3138 } else {
3139 if (last_entry_frame != NULL) {
3140 // JNI locals for the entry frame
3141 assert(last_entry_frame->is_entry_frame(), "checking");
3142 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3143 }
3144 }
3145 }
3146 last_entry_frame = NULL;
3147 depth++;
3148 } else {
3149 // externalVFrame - for an entry frame then we report the JNI locals
3150 // when we find the corresponding javaVFrame
3151 frame* fr = vf->frame_pointer();
3152 assert(fr != NULL, "sanity check");
3153 if (fr->is_entry_frame()) {
3154 last_entry_frame = fr;
3155 }
3156 }
3157
3158 vf = vf->sender();
3159 is_top_frame = false;
3160 }
3161 } else {
3162 // no last java frame but there may be JNI locals
3163 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3164 java_thread->active_handles()->oops_do(blk);
3165 }
3166 return true;
3167 }
3168
3169
3170 // Collects the simple roots for all threads and collects all
3171 // stack roots - for each thread it walks the execution
3172 // stack to find all references and local JNI refs.
3173 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3174 JNILocalRootsClosure blk;
3175 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3176 oop threadObj = thread->threadObj();
3177 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3178 // Collect the simple root for this thread before we
3179 // collect its stack roots
3180 if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD,
3181 threadObj)) {
3182 return false;
3183 }
3184 if (!collect_stack_roots(thread, &blk)) {
3185 return false;
3186 }
3187 }
3188 }
3189 return true;
3190 }
3191
3192 // visit an object
3193 // first mark the object as visited
3194 // second get all the outbound references from this object (in other words, all
3195 // the objects referenced by this object).
3196 //
3197 bool VM_HeapWalkOperation::visit(oop o) {
3198 // mark object as visited
3199 assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3200 ObjectMarker::mark(o);
3201
3202 // instance
3203 if (o->is_instance()) {
3204 if (o->klass() == SystemDictionary::Class_klass()) {
3205 if (!java_lang_Class::is_primitive(o)) {
3206 // a java.lang.Class
3207 return iterate_over_class(o);
3208 }
3209 } else {
3210 return iterate_over_object(o);
3211 }
3212 }
3213
3214 // object array
3215 if (o->is_objArray()) {
3216 return iterate_over_array(o);
3217 }
3218
3219 // type array
3220 if (o->is_typeArray()) {
3221 return iterate_over_type_array(o);
3222 }
3223
3224 return true;
3225 }
3226
3227 void VM_HeapWalkOperation::doit() {
3228 ResourceMark rm;
3229 ObjectMarkerController marker;
3230 ClassFieldMapCacheMark cm;
3231
3232 assert(visit_stack()->is_empty(), "visit stack must be empty");
3233
3234 // the heap walk starts with an initial object or the heap roots
3235 if (initial_object().is_null()) {
3236 // If either collect_stack_roots() or collect_simple_roots()
3237 // returns false at this point, then there are no mark bits
3238 // to reset.
3239 ObjectMarker::set_needs_reset(false);
3240
3241 // Calling collect_stack_roots() before collect_simple_roots()
3242 // can result in a big performance boost for an agent that is
3243 // focused on analyzing references in the thread stacks.
3244 if (!collect_stack_roots()) return;
3245
3246 if (!collect_simple_roots()) return;
3247
3248 // no early return so enable heap traversal to reset the mark bits
3249 ObjectMarker::set_needs_reset(true);
3250 } else {
3251 visit_stack()->push(initial_object()());
3252 }
3253
3254 // object references required
3255 if (is_following_references()) {
3256
3257 // visit each object until all reachable objects have been
3258 // visited or the callback asked to terminate the iteration.
3259 while (!visit_stack()->is_empty()) {
3260 oop o = visit_stack()->pop();
3261 if (!ObjectMarker::visited(o)) {
3262 if (!visit(o)) {
3263 break;
3264 }
3265 }
3266 }
3267 }
3268 }
3269
3270 // iterate over all objects that are reachable from a set of roots
3271 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3272 jvmtiStackReferenceCallback stack_ref_callback,
3273 jvmtiObjectReferenceCallback object_ref_callback,
3274 const void* user_data) {
3275 MutexLocker ml(Heap_lock);
3276 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3277 VM_HeapWalkOperation op(this, Handle(), context, user_data);
3278 VMThread::execute(&op);
3279 }
3280
3281 // iterate over all objects that are reachable from a given object
3282 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3283 jvmtiObjectReferenceCallback object_ref_callback,
3284 const void* user_data) {
3285 oop obj = JNIHandles::resolve(object);
3286 Handle initial_object(Thread::current(), obj);
3287
3288 MutexLocker ml(Heap_lock);
3289 BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3290 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3291 VMThread::execute(&op);
3292 }
3293
3294 // follow references from an initial object or the GC roots
3295 void JvmtiTagMap::follow_references(jint heap_filter,
3296 Klass* klass,
3297 jobject object,
3298 const jvmtiHeapCallbacks* callbacks,
3299 const void* user_data)
3300 {
3301 oop obj = JNIHandles::resolve(object);
3302 Handle initial_object(Thread::current(), obj);
3303
3304 MutexLocker ml(Heap_lock);
3305 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3306 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3307 VMThread::execute(&op);
3308 }
3309
3310
3311 void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
3312 // No locks during VM bring-up (0 threads) and no safepoints after main
3313 // thread creation and before VMThread creation (1 thread); initial GC
3314 // verification can happen in that window which gets to here.
3315 assert(Threads::number_of_threads() <= 1 ||
3316 SafepointSynchronize::is_at_safepoint(),
3317 "must be executed at a safepoint");
3318 if (JvmtiEnv::environments_might_exist()) {
3319 JvmtiEnvIterator it;
3320 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3321 JvmtiTagMap* tag_map = env->tag_map();
3322 if (tag_map != NULL && !tag_map->is_empty()) {
3323 tag_map->do_weak_oops(is_alive, f);
3324 }
3325 }
3326 }
3327 }
3328
3329 void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
3330
3331 // does this environment have the OBJECT_FREE event enabled
3332 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3333
3334 // counters used for trace message
3335 int freed = 0;
3336 int moved = 0;
3337
3338 JvmtiTagHashmap* hashmap = this->hashmap();
3339
3340 // reenable sizing (if disabled)
3341 hashmap->set_resizing_enabled(true);
3342
3343 // if the hashmap is empty then we can skip it
3344 if (hashmap->_entry_count == 0) {
3345 return;
3346 }
3347
3348 // now iterate through each entry in the table
3349
3350 JvmtiTagHashmapEntry** table = hashmap->table();
3351 int size = hashmap->size();
3352
3353 JvmtiTagHashmapEntry* delayed_add = NULL;
3354
3355 for (int pos = 0; pos < size; ++pos) {
3356 JvmtiTagHashmapEntry* entry = table[pos];
3357 JvmtiTagHashmapEntry* prev = NULL;
3358
3359 while (entry != NULL) {
3360 JvmtiTagHashmapEntry* next = entry->next();
3361
3362 oop* obj = entry->object_addr();
3363
3364 // has object been GC'ed
3365 if (!is_alive->do_object_b(entry->object())) {
3366 // grab the tag
3367 jlong tag = entry->tag();
3368 guarantee(tag != 0, "checking");
3369
3370 // remove GC'ed entry from hashmap and return the
3371 // entry to the free list
3372 hashmap->remove(prev, pos, entry);
3373 destroy_entry(entry);
3374
3375 // post the event to the profiler
3376 if (post_object_free) {
3377 JvmtiExport::post_object_free(env(), tag);
3378 }
3379
3380 ++freed;
3381 } else {
3382 f->do_oop(entry->object_addr());
3383 oop new_oop = entry->object();
3384
3385 // if the object has moved then re-hash it and move its
3386 // entry to its new location.
3387 unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
3388 if (new_pos != (unsigned int)pos) {
3389 if (prev == NULL) {
3390 table[pos] = next;
3391 } else {
3392 prev->set_next(next);
3393 }
3394 if (new_pos < (unsigned int)pos) {
3395 entry->set_next(table[new_pos]);
3396 table[new_pos] = entry;
3397 } else {
3398 // Delay adding this entry to it's new position as we'd end up
3399 // hitting it again during this iteration.
3400 entry->set_next(delayed_add);
3401 delayed_add = entry;
3402 }
3403 moved++;
3404 } else {
3405 // object didn't move
3406 prev = entry;
3407 }
3408 }
3409
3410 entry = next;
3411 }
3412 }
3413
3414 // Re-add all the entries which were kept aside
3415 while (delayed_add != NULL) {
3416 JvmtiTagHashmapEntry* next = delayed_add->next();
3417 unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
3418 delayed_add->set_next(table[pos]);
3419 table[pos] = delayed_add;
3420 delayed_add = next;
3421 }
3422
3423 log_debug(jvmti, objecttagging)("(%d->%d, %d freed, %d total moves)",
3424 hashmap->_entry_count + freed, hashmap->_entry_count, freed, moved);
3425 }