1 /*
2 * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "jvmtifiles/jvmtiEnv.hpp"
30 #include "oops/instanceMirrorKlass.hpp"
31 #include "oops/objArrayKlass.hpp"
32 #include "oops/oop.inline2.hpp"
33 #include "prims/jvmtiEventController.hpp"
34 #include "prims/jvmtiEventController.inline.hpp"
35 #include "prims/jvmtiExport.hpp"
36 #include "prims/jvmtiImpl.hpp"
37 #include "prims/jvmtiTagMap.hpp"
38 #include "runtime/biasedLocking.hpp"
39 #include "runtime/javaCalls.hpp"
40 #include "runtime/jniHandles.hpp"
41 #include "runtime/mutex.hpp"
42 #include "runtime/mutexLocker.hpp"
43 #include "runtime/reflectionUtils.hpp"
44 #include "runtime/vframe.hpp"
45 #include "runtime/vmThread.hpp"
46 #include "runtime/vm_operations.hpp"
47 #include "services/serviceUtil.hpp"
48 #include "utilities/macros.hpp"
49 #if INCLUDE_ALL_GCS
50 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
51 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
52 #endif // INCLUDE_ALL_GCS
53
54 // JvmtiTagHashmapEntry
55 //
56 // Each entry encapsulates a reference to the tagged object
57 // and the tag value. In addition an entry includes a next pointer which
58 // is used to chain entries together.
59
60 class JvmtiTagHashmapEntry : public CHeapObj<mtInternal> {
61 private:
62 friend class JvmtiTagMap;
63
64 oop _object; // tagged object
65 jlong _tag; // the tag
66 JvmtiTagHashmapEntry* _next; // next on the list
67
68 inline void init(oop object, jlong tag) {
69 _object = object;
70 _tag = tag;
71 _next = NULL;
72 }
73
74 // constructor
75 JvmtiTagHashmapEntry(oop object, jlong tag) { init(object, tag); }
76
77 public:
78
79 // accessor methods
80 inline oop object() const { return _object; }
81 inline oop* object_addr() { return &_object; }
82 inline jlong tag() const { return _tag; }
83
84 inline void set_tag(jlong tag) {
85 assert(tag != 0, "can't be zero");
86 _tag = tag;
87 }
88
89 inline JvmtiTagHashmapEntry* next() const { return _next; }
90 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; }
91 };
92
93
94 // JvmtiTagHashmap
95 //
96 // A hashmap is essentially a table of pointers to entries. Entries
97 // are hashed to a location, or position in the table, and then
98 // chained from that location. The "key" for hashing is address of
99 // the object, or oop. The "value" is the tag value.
100 //
101 // A hashmap maintains a count of the number entries in the hashmap
102 // and resizes if the number of entries exceeds a given threshold.
103 // The threshold is specified as a percentage of the size - for
104 // example a threshold of 0.75 will trigger the hashmap to resize
105 // if the number of entries is >75% of table size.
106 //
107 // A hashmap provides functions for adding, removing, and finding
108 // entries. It also provides a function to iterate over all entries
109 // in the hashmap.
110
111 class JvmtiTagHashmap : public CHeapObj<mtInternal> {
112 private:
113 friend class JvmtiTagMap;
114
115 enum {
116 small_trace_threshold = 10000, // threshold for tracing
117 medium_trace_threshold = 100000,
118 large_trace_threshold = 1000000,
119 initial_trace_threshold = small_trace_threshold
120 };
121
122 static int _sizes[]; // array of possible hashmap sizes
123 int _size; // actual size of the table
124 int _size_index; // index into size table
125
126 int _entry_count; // number of entries in the hashmap
127
128 float _load_factor; // load factor as a % of the size
129 int _resize_threshold; // computed threshold to trigger resizing.
130 bool _resizing_enabled; // indicates if hashmap can resize
131
132 int _trace_threshold; // threshold for trace messages
133
134 JvmtiTagHashmapEntry** _table; // the table of entries.
135
136 // private accessors
137 int resize_threshold() const { return _resize_threshold; }
138 int trace_threshold() const { return _trace_threshold; }
139
140 // initialize the hashmap
141 void init(int size_index=0, float load_factor=4.0f) {
142 int initial_size = _sizes[size_index];
143 _size_index = size_index;
144 _size = initial_size;
145 _entry_count = 0;
146 if (TraceJVMTIObjectTagging) {
147 _trace_threshold = initial_trace_threshold;
148 } else {
149 _trace_threshold = -1;
150 }
151 _load_factor = load_factor;
152 _resize_threshold = (int)(_load_factor * _size);
153 _resizing_enabled = true;
154 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
155 _table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
156 if (_table == NULL) {
157 vm_exit_out_of_memory(s, OOM_MALLOC_ERROR,
158 "unable to allocate initial hashtable for jvmti object tags");
159 }
160 for (int i=0; i<initial_size; i++) {
161 _table[i] = NULL;
162 }
163 }
164
165 // hash a given key (oop) with the specified size
166 static unsigned int hash(oop key, int size) {
167 // shift right to get better distribution (as these bits will be zero
168 // with aligned addresses)
169 unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key));
170 #ifdef _LP64
171 return (addr >> 3) % size;
172 #else
173 return (addr >> 2) % size;
174 #endif
175 }
176
177 // hash a given key (oop)
178 unsigned int hash(oop key) {
179 return hash(key, _size);
180 }
181
182 // resize the hashmap - allocates a large table and re-hashes
183 // all entries into the new table.
184 void resize() {
185 int new_size_index = _size_index+1;
186 int new_size = _sizes[new_size_index];
187 if (new_size < 0) {
188 // hashmap already at maximum capacity
189 return;
190 }
191
192 // allocate new table
193 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
194 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
195 if (new_table == NULL) {
196 warning("unable to allocate larger hashtable for jvmti object tags");
197 set_resizing_enabled(false);
198 return;
199 }
200
201 // initialize new table
202 int i;
203 for (i=0; i<new_size; i++) {
204 new_table[i] = NULL;
205 }
206
207 // rehash all entries into the new table
208 for (i=0; i<_size; i++) {
209 JvmtiTagHashmapEntry* entry = _table[i];
210 while (entry != NULL) {
211 JvmtiTagHashmapEntry* next = entry->next();
212 oop key = entry->object();
213 assert(key != NULL, "jni weak reference cleared!!");
214 unsigned int h = hash(key, new_size);
215 JvmtiTagHashmapEntry* anchor = new_table[h];
216 if (anchor == NULL) {
217 new_table[h] = entry;
218 entry->set_next(NULL);
219 } else {
220 entry->set_next(anchor);
221 new_table[h] = entry;
222 }
223 entry = next;
224 }
225 }
226
227 // free old table and update settings.
228 os::free((void*)_table);
229 _table = new_table;
230 _size_index = new_size_index;
231 _size = new_size;
232
233 // compute new resize threshold
234 _resize_threshold = (int)(_load_factor * _size);
235 }
236
237
238 // internal remove function - remove an entry at a given position in the
239 // table.
240 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
241 assert(pos >= 0 && pos < _size, "out of range");
242 if (prev == NULL) {
243 _table[pos] = entry->next();
244 } else {
245 prev->set_next(entry->next());
246 }
247 assert(_entry_count > 0, "checking");
248 _entry_count--;
249 }
250
251 // resizing switch
252 bool is_resizing_enabled() const { return _resizing_enabled; }
253 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; }
254
255 // debugging
256 void print_memory_usage();
257 void compute_next_trace_threshold();
258
259 public:
260
261 // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
262 // The preferred size is rounded down to an actual size.
263 JvmtiTagHashmap(int size, float load_factor=0.0f) {
264 int i=0;
265 while (_sizes[i] < size) {
266 if (_sizes[i] < 0) {
267 assert(i > 0, "sanity check");
268 i--;
269 break;
270 }
271 i++;
272 }
273
274 // if a load factor is specified then use it, otherwise use default
275 if (load_factor > 0.01f) {
276 init(i, load_factor);
277 } else {
278 init(i);
279 }
280 }
281
282 // create a JvmtiTagHashmap with default settings
283 JvmtiTagHashmap() {
284 init();
285 }
286
287 // release table when JvmtiTagHashmap destroyed
288 ~JvmtiTagHashmap() {
289 if (_table != NULL) {
290 os::free((void*)_table);
291 _table = NULL;
292 }
293 }
294
295 // accessors
296 int size() const { return _size; }
297 JvmtiTagHashmapEntry** table() const { return _table; }
298 int entry_count() const { return _entry_count; }
299
300 // find an entry in the hashmap, returns NULL if not found.
301 inline JvmtiTagHashmapEntry* find(oop key) {
302 unsigned int h = hash(key);
303 JvmtiTagHashmapEntry* entry = _table[h];
304 while (entry != NULL) {
305 if (entry->object() == key) {
306 return entry;
307 }
308 entry = entry->next();
309 }
310 return NULL;
311 }
312
313
314 // add a new entry to hashmap
315 inline void add(oop key, JvmtiTagHashmapEntry* entry) {
316 assert(key != NULL, "checking");
317 assert(find(key) == NULL, "duplicate detected");
318 unsigned int h = hash(key);
319 JvmtiTagHashmapEntry* anchor = _table[h];
320 if (anchor == NULL) {
321 _table[h] = entry;
322 entry->set_next(NULL);
323 } else {
324 entry->set_next(anchor);
325 _table[h] = entry;
326 }
327
328 _entry_count++;
329 if (trace_threshold() > 0 && entry_count() >= trace_threshold()) {
330 assert(TraceJVMTIObjectTagging, "should only get here when tracing");
331 print_memory_usage();
332 compute_next_trace_threshold();
333 }
334
335 // if the number of entries exceed the threshold then resize
336 if (entry_count() > resize_threshold() && is_resizing_enabled()) {
337 resize();
338 }
339 }
340
341 // remove an entry with the given key.
342 inline JvmtiTagHashmapEntry* remove(oop key) {
343 unsigned int h = hash(key);
344 JvmtiTagHashmapEntry* entry = _table[h];
345 JvmtiTagHashmapEntry* prev = NULL;
346 while (entry != NULL) {
347 if (key == entry->object()) {
348 break;
349 }
350 prev = entry;
351 entry = entry->next();
352 }
353 if (entry != NULL) {
354 remove(prev, h, entry);
355 }
356 return entry;
357 }
358
359 // iterate over all entries in the hashmap
360 void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
361 };
362
363 // possible hashmap sizes - odd primes that roughly double in size.
364 // To avoid excessive resizing the odd primes from 4801-76831 and
365 // 76831-307261 have been removed. The list must be terminated by -1.
366 int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891,
367 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
368
369
370 // A supporting class for iterating over all entries in Hashmap
371 class JvmtiTagHashmapEntryClosure {
372 public:
373 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
374 };
375
376
377 // iterate over all entries in the hashmap
378 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
379 for (int i=0; i<_size; i++) {
380 JvmtiTagHashmapEntry* entry = _table[i];
381 JvmtiTagHashmapEntry* prev = NULL;
382 while (entry != NULL) {
383 // obtain the next entry before invoking do_entry - this is
384 // necessary because do_entry may remove the entry from the
385 // hashmap.
386 JvmtiTagHashmapEntry* next = entry->next();
387 closure->do_entry(entry);
388 entry = next;
389 }
390 }
391 }
392
393 // debugging
394 void JvmtiTagHashmap::print_memory_usage() {
395 intptr_t p = (intptr_t)this;
396 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
397
398 // table + entries in KB
399 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
400 entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
401
402 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
403 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
404 entry_count(), hashmap_usage, weak_globals_usage);
405 }
406
407 // compute threshold for the next trace message
408 void JvmtiTagHashmap::compute_next_trace_threshold() {
409 if (trace_threshold() < medium_trace_threshold) {
410 _trace_threshold += small_trace_threshold;
411 } else {
412 if (trace_threshold() < large_trace_threshold) {
413 _trace_threshold += medium_trace_threshold;
414 } else {
415 _trace_threshold += large_trace_threshold;
416 }
417 }
418 }
419
420 // create a JvmtiTagMap
421 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
422 _env(env),
423 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
424 _free_entries(NULL),
425 _free_entries_count(0)
426 {
427 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
428 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
429
430 _hashmap = new JvmtiTagHashmap();
431
432 // finally add us to the environment
433 ((JvmtiEnvBase *)env)->release_set_tag_map(this);
434 }
435
436
437 // destroy a JvmtiTagMap
438 JvmtiTagMap::~JvmtiTagMap() {
439
440 // no lock acquired as we assume the enclosing environment is
441 // also being destroryed.
442 ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
443
444 JvmtiTagHashmapEntry** table = _hashmap->table();
445 for (int j = 0; j < _hashmap->size(); j++) {
446 JvmtiTagHashmapEntry* entry = table[j];
447 while (entry != NULL) {
448 JvmtiTagHashmapEntry* next = entry->next();
449 delete entry;
450 entry = next;
451 }
452 }
453
454 // finally destroy the hashmap
455 delete _hashmap;
456 _hashmap = NULL;
457
458 // remove any entries on the free list
459 JvmtiTagHashmapEntry* entry = _free_entries;
460 while (entry != NULL) {
461 JvmtiTagHashmapEntry* next = entry->next();
462 delete entry;
463 entry = next;
464 }
465 _free_entries = NULL;
466 }
467
468 // create a hashmap entry
469 // - if there's an entry on the (per-environment) free list then this
470 // is returned. Otherwise an new entry is allocated.
471 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
472 assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
473 JvmtiTagHashmapEntry* entry;
474 if (_free_entries == NULL) {
475 entry = new JvmtiTagHashmapEntry(ref, tag);
476 } else {
477 assert(_free_entries_count > 0, "mismatched _free_entries_count");
478 _free_entries_count--;
479 entry = _free_entries;
480 _free_entries = entry->next();
481 entry->init(ref, tag);
482 }
483 return entry;
484 }
485
486 // destroy an entry by returning it to the free list
487 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
488 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
489 // limit the size of the free list
490 if (_free_entries_count >= max_free_entries) {
491 delete entry;
492 } else {
493 entry->set_next(_free_entries);
494 _free_entries = entry;
495 _free_entries_count++;
496 }
497 }
498
499 // returns the tag map for the given environments. If the tag map
500 // doesn't exist then it is created.
501 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
502 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map_acquire();
503 if (tag_map == NULL) {
504 MutexLocker mu(JvmtiThreadState_lock);
505 tag_map = ((JvmtiEnvBase*)env)->tag_map();
506 if (tag_map == NULL) {
507 tag_map = new JvmtiTagMap(env);
508 }
509 } else {
510 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
511 }
512 return tag_map;
513 }
514
515 // iterate over all entries in the tag map.
516 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
517 hashmap()->entry_iterate(closure);
518 }
519
520 // returns true if the hashmaps are empty
521 bool JvmtiTagMap::is_empty() {
522 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
523 return hashmap()->entry_count() == 0;
524 }
525
526
527 // Return the tag value for an object, or 0 if the object is
528 // not tagged
529 //
530 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
531 JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
532 if (entry == NULL) {
533 return 0;
534 } else {
535 return entry->tag();
536 }
537 }
538
539
540 // A CallbackWrapper is a support class for querying and tagging an object
541 // around a callback to a profiler. The constructor does pre-callback
542 // work to get the tag value, klass tag value, ... and the destructor
543 // does the post-callback work of tagging or untagging the object.
544 //
545 // {
546 // CallbackWrapper wrapper(tag_map, o);
547 //
548 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
549 //
550 // } // wrapper goes out of scope here which results in the destructor
551 // checking to see if the object has been tagged, untagged, or the
552 // tag value has changed.
553 //
554 class CallbackWrapper : public StackObj {
555 private:
556 JvmtiTagMap* _tag_map;
557 JvmtiTagHashmap* _hashmap;
558 JvmtiTagHashmapEntry* _entry;
559 oop _o;
560 jlong _obj_size;
561 jlong _obj_tag;
562 jlong _klass_tag;
563
564 protected:
565 JvmtiTagMap* tag_map() const { return _tag_map; }
566
567 // invoked post-callback to tag, untag, or update the tag of an object
568 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
569 JvmtiTagHashmapEntry* entry, jlong obj_tag);
570 public:
571 CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
572 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
573 "MT unsafe or must be VM thread");
574
575 // object to tag
576 _o = o;
577
578 // object size
579 _obj_size = (jlong)_o->size() * wordSize;
580
581 // record the context
582 _tag_map = tag_map;
583 _hashmap = tag_map->hashmap();
584 _entry = _hashmap->find(_o);
585
586 // get object tag
587 _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
588
589 // get the class and the class's tag value
590 assert(SystemDictionary::Class_klass()->oop_is_instanceMirror(), "Is not?");
591
592 _klass_tag = tag_for(tag_map, _o->klass()->java_mirror());
593 }
594
595 ~CallbackWrapper() {
596 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
597 }
598
599 inline jlong* obj_tag_p() { return &_obj_tag; }
600 inline jlong obj_size() const { return _obj_size; }
601 inline jlong obj_tag() const { return _obj_tag; }
602 inline jlong klass_tag() const { return _klass_tag; }
603 };
604
605
606
607 // callback post-callback to tag, untag, or update the tag of an object
608 void inline CallbackWrapper::post_callback_tag_update(oop o,
609 JvmtiTagHashmap* hashmap,
610 JvmtiTagHashmapEntry* entry,
611 jlong obj_tag) {
612 if (entry == NULL) {
613 if (obj_tag != 0) {
614 // callback has tagged the object
615 assert(Thread::current()->is_VM_thread(), "must be VMThread");
616 entry = tag_map()->create_entry(o, obj_tag);
617 hashmap->add(o, entry);
618 }
619 } else {
620 // object was previously tagged - the callback may have untagged
621 // the object or changed the tag value
622 if (obj_tag == 0) {
623
624 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
625 assert(entry_removed == entry, "checking");
626 tag_map()->destroy_entry(entry);
627
628 } else {
629 if (obj_tag != entry->tag()) {
630 entry->set_tag(obj_tag);
631 }
632 }
633 }
634 }
635
636 // An extended CallbackWrapper used when reporting an object reference
637 // to the agent.
638 //
639 // {
640 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
641 //
642 // (*callback)(wrapper.klass_tag(),
643 // wrapper.obj_size(),
644 // wrapper.obj_tag_p()
645 // wrapper.referrer_tag_p(), ...)
646 //
647 // } // wrapper goes out of scope here which results in the destructor
648 // checking to see if the referrer object has been tagged, untagged,
649 // or the tag value has changed.
650 //
651 class TwoOopCallbackWrapper : public CallbackWrapper {
652 private:
653 bool _is_reference_to_self;
654 JvmtiTagHashmap* _referrer_hashmap;
655 JvmtiTagHashmapEntry* _referrer_entry;
656 oop _referrer;
657 jlong _referrer_obj_tag;
658 jlong _referrer_klass_tag;
659 jlong* _referrer_tag_p;
660
661 bool is_reference_to_self() const { return _is_reference_to_self; }
662
663 public:
664 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
665 CallbackWrapper(tag_map, o)
666 {
667 // self reference needs to be handled in a special way
668 _is_reference_to_self = (referrer == o);
669
670 if (_is_reference_to_self) {
671 _referrer_klass_tag = klass_tag();
672 _referrer_tag_p = obj_tag_p();
673 } else {
674 _referrer = referrer;
675 // record the context
676 _referrer_hashmap = tag_map->hashmap();
677 _referrer_entry = _referrer_hashmap->find(_referrer);
678
679 // get object tag
680 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
681 _referrer_tag_p = &_referrer_obj_tag;
682
683 // get referrer class tag.
684 _referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror());
685 }
686 }
687
688 ~TwoOopCallbackWrapper() {
689 if (!is_reference_to_self()){
690 post_callback_tag_update(_referrer,
691 _referrer_hashmap,
692 _referrer_entry,
693 _referrer_obj_tag);
694 }
695 }
696
697 // address of referrer tag
698 // (for a self reference this will return the same thing as obj_tag_p())
699 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
700
701 // referrer's class tag
702 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
703 };
704
705 // tag an object
706 //
707 // This function is performance critical. If many threads attempt to tag objects
708 // around the same time then it's possible that the Mutex associated with the
709 // tag map will be a hot lock.
710 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
711 MutexLocker ml(lock());
712
713 // resolve the object
714 oop o = JNIHandles::resolve_non_null(object);
715
716 // see if the object is already tagged
717 JvmtiTagHashmap* hashmap = _hashmap;
718 JvmtiTagHashmapEntry* entry = hashmap->find(o);
719
720 // if the object is not already tagged then we tag it
721 if (entry == NULL) {
722 if (tag != 0) {
723 entry = create_entry(o, tag);
724 hashmap->add(o, entry);
725 } else {
726 // no-op
727 }
728 } else {
729 // if the object is already tagged then we either update
730 // the tag (if a new tag value has been provided)
731 // or remove the object if the new tag value is 0.
732 if (tag == 0) {
733 hashmap->remove(o);
734 destroy_entry(entry);
735 } else {
736 entry->set_tag(tag);
737 }
738 }
739 }
740
741 // get the tag for an object
742 jlong JvmtiTagMap::get_tag(jobject object) {
743 MutexLocker ml(lock());
744
745 // resolve the object
746 oop o = JNIHandles::resolve_non_null(object);
747
748 return tag_for(this, o);
749 }
750
751
752 // Helper class used to describe the static or instance fields of a class.
753 // For each field it holds the field index (as defined by the JVMTI specification),
754 // the field type, and the offset.
755
756 class ClassFieldDescriptor: public CHeapObj<mtInternal> {
757 private:
758 int _field_index;
759 int _field_offset;
760 char _field_type;
761 public:
762 ClassFieldDescriptor(int index, char type, int offset) :
763 _field_index(index), _field_type(type), _field_offset(offset) {
764 }
765 int field_index() const { return _field_index; }
766 char field_type() const { return _field_type; }
767 int field_offset() const { return _field_offset; }
768 };
769
770 class ClassFieldMap: public CHeapObj<mtInternal> {
771 private:
772 enum {
773 initial_field_count = 5
774 };
775
776 // list of field descriptors
777 GrowableArray<ClassFieldDescriptor*>* _fields;
778
779 // constructor
780 ClassFieldMap();
781
782 // add a field
783 void add(int index, char type, int offset);
784
785 // returns the field count for the given class
786 static int compute_field_count(instanceKlassHandle ikh);
787
788 public:
789 ~ClassFieldMap();
790
791 // access
792 int field_count() { return _fields->length(); }
793 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
794
795 // functions to create maps of static or instance fields
796 static ClassFieldMap* create_map_of_static_fields(Klass* k);
797 static ClassFieldMap* create_map_of_instance_fields(oop obj);
798 };
799
800 ClassFieldMap::ClassFieldMap() {
801 _fields = new (ResourceObj::C_HEAP, mtInternal)
802 GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
803 }
804
805 ClassFieldMap::~ClassFieldMap() {
806 for (int i=0; i<_fields->length(); i++) {
807 delete _fields->at(i);
808 }
809 delete _fields;
810 }
811
812 void ClassFieldMap::add(int index, char type, int offset) {
813 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
814 _fields->append(field);
815 }
816
817 // Returns a heap allocated ClassFieldMap to describe the static fields
818 // of the given class.
819 //
820 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
821 HandleMark hm;
822 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
823
824 // create the field map
825 ClassFieldMap* field_map = new ClassFieldMap();
826
827 FilteredFieldStream f(ikh, false, false);
828 int max_field_index = f.field_count()-1;
829
830 int index = 0;
831 for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
832 // ignore instance fields
833 if (!fld.access_flags().is_static()) {
834 continue;
835 }
836 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
837 }
838 return field_map;
839 }
840
841 // Returns a heap allocated ClassFieldMap to describe the instance fields
842 // of the given class. All instance fields are included (this means public
843 // and private fields declared in superclasses and superinterfaces too).
844 //
845 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
846 HandleMark hm;
847 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
848
849 // create the field map
850 ClassFieldMap* field_map = new ClassFieldMap();
851
852 FilteredFieldStream f(ikh, false, false);
853
854 int max_field_index = f.field_count()-1;
855
856 int index = 0;
857 for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
858 // ignore static fields
859 if (fld.access_flags().is_static()) {
860 continue;
861 }
862 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
863 }
864
865 return field_map;
866 }
867
868 // Helper class used to cache a ClassFileMap for the instance fields of
869 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
870 // heap iteration and avoid creating a field map for each object in the heap
871 // (only need to create the map when the first instance of a class is encountered).
872 //
873 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
874 private:
875 enum {
876 initial_class_count = 200
877 };
878 ClassFieldMap* _field_map;
879
880 ClassFieldMap* field_map() const { return _field_map; }
881
882 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
883 ~JvmtiCachedClassFieldMap();
884
885 static GrowableArray<InstanceKlass*>* _class_list;
886 static void add_to_class_list(InstanceKlass* ik);
887
888 public:
889 // returns the field map for a given object (returning map cached
890 // by InstanceKlass if possible
891 static ClassFieldMap* get_map_of_instance_fields(oop obj);
892
893 // removes the field map from all instanceKlasses - should be
894 // called before VM operation completes
895 static void clear_cache();
896
897 // returns the number of ClassFieldMap cached by instanceKlasses
898 static int cached_field_map_count();
899 };
900
901 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
902
903 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
904 _field_map = field_map;
905 }
906
907 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
908 if (_field_map != NULL) {
909 delete _field_map;
910 }
911 }
912
913 // Marker class to ensure that the class file map cache is only used in a defined
914 // scope.
915 class ClassFieldMapCacheMark : public StackObj {
916 private:
917 static bool _is_active;
918 public:
919 ClassFieldMapCacheMark() {
920 assert(Thread::current()->is_VM_thread(), "must be VMThread");
921 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
922 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
923 _is_active = true;
924 }
925 ~ClassFieldMapCacheMark() {
926 JvmtiCachedClassFieldMap::clear_cache();
927 _is_active = false;
928 }
929 static bool is_active() { return _is_active; }
930 };
931
932 bool ClassFieldMapCacheMark::_is_active;
933
934
935 // record that the given InstanceKlass is caching a field map
936 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
937 if (_class_list == NULL) {
938 _class_list = new (ResourceObj::C_HEAP, mtInternal)
939 GrowableArray<InstanceKlass*>(initial_class_count, true);
940 }
941 _class_list->push(ik);
942 }
943
944 // returns the instance field map for the given object
945 // (returns field map cached by the InstanceKlass if possible)
946 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
947 assert(Thread::current()->is_VM_thread(), "must be VMThread");
948 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
949
950 Klass* k = obj->klass();
951 InstanceKlass* ik = InstanceKlass::cast(k);
952
953 // return cached map if possible
954 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
955 if (cached_map != NULL) {
956 assert(cached_map->field_map() != NULL, "missing field list");
957 return cached_map->field_map();
958 } else {
959 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
960 cached_map = new JvmtiCachedClassFieldMap(field_map);
961 ik->set_jvmti_cached_class_field_map(cached_map);
962 add_to_class_list(ik);
963 return field_map;
964 }
965 }
966
967 // remove the fields maps cached from all instanceKlasses
968 void JvmtiCachedClassFieldMap::clear_cache() {
969 assert(Thread::current()->is_VM_thread(), "must be VMThread");
970 if (_class_list != NULL) {
971 for (int i = 0; i < _class_list->length(); i++) {
972 InstanceKlass* ik = _class_list->at(i);
973 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
974 assert(cached_map != NULL, "should not be NULL");
975 ik->set_jvmti_cached_class_field_map(NULL);
976 delete cached_map; // deletes the encapsulated field map
977 }
978 delete _class_list;
979 _class_list = NULL;
980 }
981 }
982
983 // returns the number of ClassFieldMap cached by instanceKlasses
984 int JvmtiCachedClassFieldMap::cached_field_map_count() {
985 return (_class_list == NULL) ? 0 : _class_list->length();
986 }
987
988 // helper function to indicate if an object is filtered by its tag or class tag
989 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
990 jlong klass_tag,
991 int heap_filter) {
992 // apply the heap filter
993 if (obj_tag != 0) {
994 // filter out tagged objects
995 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
996 } else {
997 // filter out untagged objects
998 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
999 }
1000 if (klass_tag != 0) {
1001 // filter out objects with tagged classes
1002 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1003 } else {
1004 // filter out objects with untagged classes.
1005 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1006 }
1007 return false;
1008 }
1009
1010 // helper function to indicate if an object is filtered by a klass filter
1011 static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
1012 if (!klass_filter.is_null()) {
1013 if (obj->klass() != klass_filter()) {
1014 return true;
1015 }
1016 }
1017 return false;
1018 }
1019
1020 // helper function to tell if a field is a primitive field or not
1021 static inline bool is_primitive_field_type(char type) {
1022 return (type != 'L' && type != '[');
1023 }
1024
1025 // helper function to copy the value from location addr to jvalue.
1026 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1027 switch (value_type) {
1028 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1029 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
1030 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
1031 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
1032 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
1033 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
1034 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
1035 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
1036 default: ShouldNotReachHere();
1037 }
1038 }
1039
1040 // helper function to invoke string primitive value callback
1041 // returns visit control flags
1042 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1043 CallbackWrapper* wrapper,
1044 oop str,
1045 void* user_data)
1046 {
1047 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1048
1049 typeArrayOop s_value = java_lang_String::value(str);
1050
1051 // JDK-6584008: the value field may be null if a String instance is
1052 // partially constructed.
1053 if (s_value == NULL) {
1054 return 0;
1055 }
1056 // get the string value and length
1057 // (string value may be offset from the base)
1058 int s_len = java_lang_String::length(str);
1059 int s_offset = java_lang_String::offset(str);
1060 jchar* value;
1061 if (s_len > 0) {
1062 value = s_value->char_at_addr(s_offset);
1063 } else {
1064 value = (jchar*) s_value->base(T_CHAR);
1065 }
1066
1067 // invoke the callback
1068 return (*cb)(wrapper->klass_tag(),
1069 wrapper->obj_size(),
1070 wrapper->obj_tag_p(),
1071 value,
1072 (jint)s_len,
1073 user_data);
1074 }
1075
1076 // helper function to invoke string primitive value callback
1077 // returns visit control flags
1078 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1079 CallbackWrapper* wrapper,
1080 oop obj,
1081 void* user_data)
1082 {
1083 assert(obj->is_typeArray(), "not a primitive array");
1084
1085 // get base address of first element
1086 typeArrayOop array = typeArrayOop(obj);
1087 BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
1088 void* elements = array->base(type);
1089
1090 // jvmtiPrimitiveType is defined so this mapping is always correct
1091 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1092
1093 return (*cb)(wrapper->klass_tag(),
1094 wrapper->obj_size(),
1095 wrapper->obj_tag_p(),
1096 (jint)array->length(),
1097 elem_type,
1098 elements,
1099 user_data);
1100 }
1101
1102 // helper function to invoke the primitive field callback for all static fields
1103 // of a given class
1104 static jint invoke_primitive_field_callback_for_static_fields
1105 (CallbackWrapper* wrapper,
1106 oop obj,
1107 jvmtiPrimitiveFieldCallback cb,
1108 void* user_data)
1109 {
1110 // for static fields only the index will be set
1111 static jvmtiHeapReferenceInfo reference_info = { 0 };
1112
1113 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1114 if (java_lang_Class::is_primitive(obj)) {
1115 return 0;
1116 }
1117 Klass* klass = java_lang_Class::as_Klass(obj);
1118
1119 // ignore classes for object and type arrays
1120 if (!klass->oop_is_instance()) {
1121 return 0;
1122 }
1123
1124 // ignore classes which aren't linked yet
1125 InstanceKlass* ik = InstanceKlass::cast(klass);
1126 if (!ik->is_linked()) {
1127 return 0;
1128 }
1129
1130 // get the field map
1131 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1132
1133 // invoke the callback for each static primitive field
1134 for (int i=0; i<field_map->field_count(); i++) {
1135 ClassFieldDescriptor* field = field_map->field_at(i);
1136
1137 // ignore non-primitive fields
1138 char type = field->field_type();
1139 if (!is_primitive_field_type(type)) {
1140 continue;
1141 }
1142 // one-to-one mapping
1143 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1144
1145 // get offset and field value
1146 int offset = field->field_offset();
1147 address addr = (address)klass->java_mirror() + offset;
1148 jvalue value;
1149 copy_to_jvalue(&value, addr, value_type);
1150
1151 // field index
1152 reference_info.field.index = field->field_index();
1153
1154 // invoke the callback
1155 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1156 &reference_info,
1157 wrapper->klass_tag(),
1158 wrapper->obj_tag_p(),
1159 value,
1160 value_type,
1161 user_data);
1162 if (res & JVMTI_VISIT_ABORT) {
1163 delete field_map;
1164 return res;
1165 }
1166 }
1167
1168 delete field_map;
1169 return 0;
1170 }
1171
1172 // helper function to invoke the primitive field callback for all instance fields
1173 // of a given object
1174 static jint invoke_primitive_field_callback_for_instance_fields(
1175 CallbackWrapper* wrapper,
1176 oop obj,
1177 jvmtiPrimitiveFieldCallback cb,
1178 void* user_data)
1179 {
1180 // for instance fields only the index will be set
1181 static jvmtiHeapReferenceInfo reference_info = { 0 };
1182
1183 // get the map of the instance fields
1184 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1185
1186 // invoke the callback for each instance primitive field
1187 for (int i=0; i<fields->field_count(); i++) {
1188 ClassFieldDescriptor* field = fields->field_at(i);
1189
1190 // ignore non-primitive fields
1191 char type = field->field_type();
1192 if (!is_primitive_field_type(type)) {
1193 continue;
1194 }
1195 // one-to-one mapping
1196 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1197
1198 // get offset and field value
1199 int offset = field->field_offset();
1200 address addr = (address)obj + offset;
1201 jvalue value;
1202 copy_to_jvalue(&value, addr, value_type);
1203
1204 // field index
1205 reference_info.field.index = field->field_index();
1206
1207 // invoke the callback
1208 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1209 &reference_info,
1210 wrapper->klass_tag(),
1211 wrapper->obj_tag_p(),
1212 value,
1213 value_type,
1214 user_data);
1215 if (res & JVMTI_VISIT_ABORT) {
1216 return res;
1217 }
1218 }
1219 return 0;
1220 }
1221
1222
1223 // VM operation to iterate over all objects in the heap (both reachable
1224 // and unreachable)
1225 class VM_HeapIterateOperation: public VM_Operation {
1226 private:
1227 ObjectClosure* _blk;
1228 public:
1229 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1230
1231 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1232 void doit() {
1233 // allows class files maps to be cached during iteration
1234 ClassFieldMapCacheMark cm;
1235
1236 // make sure that heap is parsable (fills TLABs with filler objects)
1237 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1238
1239 // Verify heap before iteration - if the heap gets corrupted then
1240 // JVMTI's IterateOverHeap will crash.
1241 if (VerifyBeforeIteration) {
1242 Universe::verify();
1243 }
1244
1245 // do the iteration
1246 // If this operation encounters a bad object when using CMS,
1247 // consider using safe_object_iterate() which avoids perm gen
1248 // objects that may contain bad references.
1249 Universe::heap()->object_iterate(_blk);
1250 }
1251
1252 };
1253
1254
1255 // An ObjectClosure used to support the deprecated IterateOverHeap and
1256 // IterateOverInstancesOfClass functions
1257 class IterateOverHeapObjectClosure: public ObjectClosure {
1258 private:
1259 JvmtiTagMap* _tag_map;
1260 KlassHandle _klass;
1261 jvmtiHeapObjectFilter _object_filter;
1262 jvmtiHeapObjectCallback _heap_object_callback;
1263 const void* _user_data;
1264
1265 // accessors
1266 JvmtiTagMap* tag_map() const { return _tag_map; }
1267 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1268 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1269 KlassHandle klass() const { return _klass; }
1270 const void* user_data() const { return _user_data; }
1271
1272 // indicates if iteration has been aborted
1273 bool _iteration_aborted;
1274 bool is_iteration_aborted() const { return _iteration_aborted; }
1275 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1276
1277 public:
1278 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1279 KlassHandle klass,
1280 jvmtiHeapObjectFilter object_filter,
1281 jvmtiHeapObjectCallback heap_object_callback,
1282 const void* user_data) :
1283 _tag_map(tag_map),
1284 _klass(klass),
1285 _object_filter(object_filter),
1286 _heap_object_callback(heap_object_callback),
1287 _user_data(user_data),
1288 _iteration_aborted(false)
1289 {
1290 }
1291
1292 void do_object(oop o);
1293 };
1294
1295 // invoked for each object in the heap
1296 void IterateOverHeapObjectClosure::do_object(oop o) {
1297 // check if iteration has been halted
1298 if (is_iteration_aborted()) return;
1299
1300 // ignore any objects that aren't visible to profiler
1301 if (!ServiceUtil::visible_oop(o)) return;
1302
1303 // instanceof check when filtering by klass
1304 if (!klass().is_null() && !o->is_a(klass()())) {
1305 return;
1306 }
1307 // prepare for the calllback
1308 CallbackWrapper wrapper(tag_map(), o);
1309
1310 // if the object is tagged and we're only interested in untagged objects
1311 // then don't invoke the callback. Similiarly, if the object is untagged
1312 // and we're only interested in tagged objects we skip the callback.
1313 if (wrapper.obj_tag() != 0) {
1314 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1315 } else {
1316 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1317 }
1318
1319 // invoke the agent's callback
1320 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1321 wrapper.obj_size(),
1322 wrapper.obj_tag_p(),
1323 (void*)user_data());
1324 if (control == JVMTI_ITERATION_ABORT) {
1325 set_iteration_aborted(true);
1326 }
1327 }
1328
1329 // An ObjectClosure used to support the IterateThroughHeap function
1330 class IterateThroughHeapObjectClosure: public ObjectClosure {
1331 private:
1332 JvmtiTagMap* _tag_map;
1333 KlassHandle _klass;
1334 int _heap_filter;
1335 const jvmtiHeapCallbacks* _callbacks;
1336 const void* _user_data;
1337
1338 // accessor functions
1339 JvmtiTagMap* tag_map() const { return _tag_map; }
1340 int heap_filter() const { return _heap_filter; }
1341 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1342 KlassHandle klass() const { return _klass; }
1343 const void* user_data() const { return _user_data; }
1344
1345 // indicates if the iteration has been aborted
1346 bool _iteration_aborted;
1347 bool is_iteration_aborted() const { return _iteration_aborted; }
1348
1349 // used to check the visit control flags. If the abort flag is set
1350 // then we set the iteration aborted flag so that the iteration completes
1351 // without processing any further objects
1352 bool check_flags_for_abort(jint flags) {
1353 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1354 if (is_abort) {
1355 _iteration_aborted = true;
1356 }
1357 return is_abort;
1358 }
1359
1360 public:
1361 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1362 KlassHandle klass,
1363 int heap_filter,
1364 const jvmtiHeapCallbacks* heap_callbacks,
1365 const void* user_data) :
1366 _tag_map(tag_map),
1367 _klass(klass),
1368 _heap_filter(heap_filter),
1369 _callbacks(heap_callbacks),
1370 _user_data(user_data),
1371 _iteration_aborted(false)
1372 {
1373 }
1374
1375 void do_object(oop o);
1376 };
1377
1378 // invoked for each object in the heap
1379 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1380 // check if iteration has been halted
1381 if (is_iteration_aborted()) return;
1382
1383 // ignore any objects that aren't visible to profiler
1384 if (!ServiceUtil::visible_oop(obj)) return;
1385
1386 // apply class filter
1387 if (is_filtered_by_klass_filter(obj, klass())) return;
1388
1389 // prepare for callback
1390 CallbackWrapper wrapper(tag_map(), obj);
1391
1392 // check if filtered by the heap filter
1393 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1394 return;
1395 }
1396
1397 // for arrays we need the length, otherwise -1
1398 bool is_array = obj->is_array();
1399 int len = is_array ? arrayOop(obj)->length() : -1;
1400
1401 // invoke the object callback (if callback is provided)
1402 if (callbacks()->heap_iteration_callback != NULL) {
1403 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1404 jint res = (*cb)(wrapper.klass_tag(),
1405 wrapper.obj_size(),
1406 wrapper.obj_tag_p(),
1407 (jint)len,
1408 (void*)user_data());
1409 if (check_flags_for_abort(res)) return;
1410 }
1411
1412 // for objects and classes we report primitive fields if callback provided
1413 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1414 jint res;
1415 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1416 if (obj->klass() == SystemDictionary::Class_klass()) {
1417 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1418 obj,
1419 cb,
1420 (void*)user_data());
1421 } else {
1422 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1423 obj,
1424 cb,
1425 (void*)user_data());
1426 }
1427 if (check_flags_for_abort(res)) return;
1428 }
1429
1430 // string callback
1431 if (!is_array &&
1432 callbacks()->string_primitive_value_callback != NULL &&
1433 obj->klass() == SystemDictionary::String_klass()) {
1434 jint res = invoke_string_value_callback(
1435 callbacks()->string_primitive_value_callback,
1436 &wrapper,
1437 obj,
1438 (void*)user_data() );
1439 if (check_flags_for_abort(res)) return;
1440 }
1441
1442 // array callback
1443 if (is_array &&
1444 callbacks()->array_primitive_value_callback != NULL &&
1445 obj->is_typeArray()) {
1446 jint res = invoke_array_primitive_value_callback(
1447 callbacks()->array_primitive_value_callback,
1448 &wrapper,
1449 obj,
1450 (void*)user_data() );
1451 if (check_flags_for_abort(res)) return;
1452 }
1453 };
1454
1455
1456 // Deprecated function to iterate over all objects in the heap
1457 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1458 KlassHandle klass,
1459 jvmtiHeapObjectCallback heap_object_callback,
1460 const void* user_data)
1461 {
1462 MutexLocker ml(Heap_lock);
1463 IterateOverHeapObjectClosure blk(this,
1464 klass,
1465 object_filter,
1466 heap_object_callback,
1467 user_data);
1468 VM_HeapIterateOperation op(&blk);
1469 VMThread::execute(&op);
1470 }
1471
1472
1473 // Iterates over all objects in the heap
1474 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1475 KlassHandle klass,
1476 const jvmtiHeapCallbacks* callbacks,
1477 const void* user_data)
1478 {
1479 MutexLocker ml(Heap_lock);
1480 IterateThroughHeapObjectClosure blk(this,
1481 klass,
1482 heap_filter,
1483 callbacks,
1484 user_data);
1485 VM_HeapIterateOperation op(&blk);
1486 VMThread::execute(&op);
1487 }
1488
1489 // support class for get_objects_with_tags
1490
1491 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1492 private:
1493 JvmtiEnv* _env;
1494 jlong* _tags;
1495 jint _tag_count;
1496
1497 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1498 GrowableArray<uint64_t>* _tag_results; // collected tags
1499
1500 public:
1501 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1502 _env = env;
1503 _tags = (jlong*)tags;
1504 _tag_count = tag_count;
1505 _object_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<jobject>(1,true);
1506 _tag_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<uint64_t>(1,true);
1507 }
1508
1509 ~TagObjectCollector() {
1510 delete _object_results;
1511 delete _tag_results;
1512 }
1513
1514 // for each tagged object check if the tag value matches
1515 // - if it matches then we create a JNI local reference to the object
1516 // and record the reference and tag value.
1517 //
1518 void do_entry(JvmtiTagHashmapEntry* entry) {
1519 for (int i=0; i<_tag_count; i++) {
1520 if (_tags[i] == entry->tag()) {
1521 oop o = entry->object();
1522 assert(o != NULL && Universe::heap()->is_in_reserved(o), "sanity check");
1523 #if INCLUDE_ALL_GCS
1524 if (UseG1GC || (UseShenandoahGC && ShenandoahSATBBarrier)) {
1525 // The reference in this tag map could be the only (implicitly weak)
1526 // reference to that object. If we hand it out, we need to keep it live wrt
1527 // SATB marking similar to other j.l.ref.Reference referents.
1528 G1SATBCardTableModRefBS::enqueue(o);
1529 }
1530 #endif
1531 jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1532 _object_results->append(ref);
1533 _tag_results->append((uint64_t)entry->tag());
1534 }
1535 }
1536 }
1537
1538 // return the results from the collection
1539 //
1540 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1541 jvmtiError error;
1542 int count = _object_results->length();
1543 assert(count >= 0, "sanity check");
1544
1545 // if object_result_ptr is not NULL then allocate the result and copy
1546 // in the object references.
1547 if (object_result_ptr != NULL) {
1548 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1549 if (error != JVMTI_ERROR_NONE) {
1550 return error;
1551 }
1552 for (int i=0; i<count; i++) {
1553 (*object_result_ptr)[i] = _object_results->at(i);
1554 }
1555 }
1556
1557 // if tag_result_ptr is not NULL then allocate the result and copy
1558 // in the tag values.
1559 if (tag_result_ptr != NULL) {
1560 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1561 if (error != JVMTI_ERROR_NONE) {
1562 if (object_result_ptr != NULL) {
1563 _env->Deallocate((unsigned char*)object_result_ptr);
1564 }
1565 return error;
1566 }
1567 for (int i=0; i<count; i++) {
1568 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1569 }
1570 }
1571
1572 *count_ptr = count;
1573 return JVMTI_ERROR_NONE;
1574 }
1575 };
1576
1577 // return the list of objects with the specified tags
1578 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1579 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1580
1581 TagObjectCollector collector(env(), tags, count);
1582 {
1583 // iterate over all tagged objects
1584 MutexLocker ml(lock());
1585 entry_iterate(&collector);
1586 }
1587 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1588 }
1589
1590
1591 // ObjectMarker is used to support the marking objects when walking the
1592 // heap.
1593 //
1594 // This implementation uses the existing mark bits in an object for
1595 // marking. Objects that are marked must later have their headers restored.
1596 // As most objects are unlocked and don't have their identity hash computed
1597 // we don't have to save their headers. Instead we save the headers that
1598 // are "interesting". Later when the headers are restored this implementation
1599 // restores all headers to their initial value and then restores the few
1600 // objects that had interesting headers.
1601 //
1602 // Future work: This implementation currently uses growable arrays to save
1603 // the oop and header of interesting objects. As an optimization we could
1604 // use the same technique as the GC and make use of the unused area
1605 // between top() and end().
1606 //
1607
1608 // An ObjectClosure used to restore the mark bits of an object
1609 class RestoreMarksClosure : public ObjectClosure {
1610 public:
1611 void do_object(oop o) {
1612 if (o != NULL) {
1613 markOop mark = o->mark();
1614 if (mark->is_marked()) {
1615 o->init_mark();
1616 }
1617 }
1618 }
1619 };
1620
1621 // ObjectMarker provides the mark and visited functions
1622 class ObjectMarker : AllStatic {
1623 private:
1624 // saved headers
1625 static GrowableArray<oop>* _saved_oop_stack;
1626 static GrowableArray<markOop>* _saved_mark_stack;
1627 static bool _needs_reset; // do we need to reset mark bits?
1628
1629 public:
1630 static void init(); // initialize
1631 static void done(); // clean-up
1632
1633 static inline void mark(oop o); // mark an object
1634 static inline bool visited(oop o); // check if object has been visited
1635
1636 static inline bool needs_reset() { return _needs_reset; }
1637 static inline void set_needs_reset(bool v) { _needs_reset = v; }
1638 };
1639
1640 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1641 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1642 bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default
1643
1644 // initialize ObjectMarker - prepares for object marking
1645 void ObjectMarker::init() {
1646 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1647
1648 // prepare heap for iteration
1649 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1650
1651 // create stacks for interesting headers
1652 _saved_mark_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<markOop>(4000, true);
1653 _saved_oop_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(4000, true);
1654
1655 if (UseBiasedLocking) {
1656 BiasedLocking::preserve_marks();
1657 }
1658 }
1659
1660 // Object marking is done so restore object headers
1661 void ObjectMarker::done() {
1662 // iterate over all objects and restore the mark bits to
1663 // their initial value
1664 RestoreMarksClosure blk;
1665 if (needs_reset()) {
1666 Universe::heap()->object_iterate(&blk);
1667 } else {
1668 // We don't need to reset mark bits on this call, but reset the
1669 // flag to the default for the next call.
1670 set_needs_reset(true);
1671 }
1672
1673 // now restore the interesting headers
1674 for (int i = 0; i < _saved_oop_stack->length(); i++) {
1675 oop o = _saved_oop_stack->at(i);
1676 markOop mark = _saved_mark_stack->at(i);
1677 o->set_mark(mark);
1678 }
1679
1680 if (UseBiasedLocking) {
1681 BiasedLocking::restore_marks();
1682 }
1683
1684 // free the stacks
1685 delete _saved_oop_stack;
1686 delete _saved_mark_stack;
1687 }
1688
1689 // mark an object
1690 inline void ObjectMarker::mark(oop o) {
1691 assert(Universe::heap()->is_in(o), "sanity check");
1692 assert(!o->mark()->is_marked(), "should only mark an object once");
1693
1694 // object's mark word
1695 markOop mark = o->mark();
1696
1697 if (mark->must_be_preserved(o)) {
1698 _saved_mark_stack->push(mark);
1699 _saved_oop_stack->push(o);
1700 }
1701
1702 // mark the object
1703 o->set_mark(markOopDesc::prototype()->set_marked());
1704 }
1705
1706 // return true if object is marked
1707 inline bool ObjectMarker::visited(oop o) {
1708 return o->mark()->is_marked();
1709 }
1710
1711 // Stack allocated class to help ensure that ObjectMarker is used
1712 // correctly. Constructor initializes ObjectMarker, destructor calls
1713 // ObjectMarker's done() function to restore object headers.
1714 class ObjectMarkerController : public StackObj {
1715 public:
1716 ObjectMarkerController() {
1717 ObjectMarker::init();
1718 }
1719 ~ObjectMarkerController() {
1720 ObjectMarker::done();
1721 }
1722 };
1723
1724
1725 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1726 // (not performance critical as only used for roots)
1727 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1728 switch (kind) {
1729 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1730 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1731 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR;
1732 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1733 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1734 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1735 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1736 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1737 }
1738 }
1739
1740 // Base class for all heap walk contexts. The base class maintains a flag
1741 // to indicate if the context is valid or not.
1742 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1743 private:
1744 bool _valid;
1745 public:
1746 HeapWalkContext(bool valid) { _valid = valid; }
1747 void invalidate() { _valid = false; }
1748 bool is_valid() const { return _valid; }
1749 };
1750
1751 // A basic heap walk context for the deprecated heap walking functions.
1752 // The context for a basic heap walk are the callbacks and fields used by
1753 // the referrer caching scheme.
1754 class BasicHeapWalkContext: public HeapWalkContext {
1755 private:
1756 jvmtiHeapRootCallback _heap_root_callback;
1757 jvmtiStackReferenceCallback _stack_ref_callback;
1758 jvmtiObjectReferenceCallback _object_ref_callback;
1759
1760 // used for caching
1761 oop _last_referrer;
1762 jlong _last_referrer_tag;
1763
1764 public:
1765 BasicHeapWalkContext() : HeapWalkContext(false) { }
1766
1767 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1768 jvmtiStackReferenceCallback stack_ref_callback,
1769 jvmtiObjectReferenceCallback object_ref_callback) :
1770 HeapWalkContext(true),
1771 _heap_root_callback(heap_root_callback),
1772 _stack_ref_callback(stack_ref_callback),
1773 _object_ref_callback(object_ref_callback),
1774 _last_referrer(NULL),
1775 _last_referrer_tag(0) {
1776 }
1777
1778 // accessors
1779 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1780 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1781 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1782
1783 oop last_referrer() const { return _last_referrer; }
1784 void set_last_referrer(oop referrer) { _last_referrer = referrer; }
1785 jlong last_referrer_tag() const { return _last_referrer_tag; }
1786 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1787 };
1788
1789 // The advanced heap walk context for the FollowReferences functions.
1790 // The context is the callbacks, and the fields used for filtering.
1791 class AdvancedHeapWalkContext: public HeapWalkContext {
1792 private:
1793 jint _heap_filter;
1794 KlassHandle _klass_filter;
1795 const jvmtiHeapCallbacks* _heap_callbacks;
1796
1797 public:
1798 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1799
1800 AdvancedHeapWalkContext(jint heap_filter,
1801 KlassHandle klass_filter,
1802 const jvmtiHeapCallbacks* heap_callbacks) :
1803 HeapWalkContext(true),
1804 _heap_filter(heap_filter),
1805 _klass_filter(klass_filter),
1806 _heap_callbacks(heap_callbacks) {
1807 }
1808
1809 // accessors
1810 jint heap_filter() const { return _heap_filter; }
1811 KlassHandle klass_filter() const { return _klass_filter; }
1812
1813 const jvmtiHeapReferenceCallback heap_reference_callback() const {
1814 return _heap_callbacks->heap_reference_callback;
1815 };
1816 const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1817 return _heap_callbacks->primitive_field_callback;
1818 }
1819 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1820 return _heap_callbacks->array_primitive_value_callback;
1821 }
1822 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1823 return _heap_callbacks->string_primitive_value_callback;
1824 }
1825 };
1826
1827 // The CallbackInvoker is a class with static functions that the heap walk can call
1828 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1829 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1830 // mode is for the newer FollowReferences function which supports a lot of
1831 // additional callbacks.
1832 class CallbackInvoker : AllStatic {
1833 private:
1834 // heap walk styles
1835 enum { basic, advanced };
1836 static int _heap_walk_type;
1837 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1838 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1839
1840 // context for basic style heap walk
1841 static BasicHeapWalkContext _basic_context;
1842 static BasicHeapWalkContext* basic_context() {
1843 assert(_basic_context.is_valid(), "invalid");
1844 return &_basic_context;
1845 }
1846
1847 // context for advanced style heap walk
1848 static AdvancedHeapWalkContext _advanced_context;
1849 static AdvancedHeapWalkContext* advanced_context() {
1850 assert(_advanced_context.is_valid(), "invalid");
1851 return &_advanced_context;
1852 }
1853
1854 // context needed for all heap walks
1855 static JvmtiTagMap* _tag_map;
1856 static const void* _user_data;
1857 static GrowableArray<oop>* _visit_stack;
1858
1859 // accessors
1860 static JvmtiTagMap* tag_map() { return _tag_map; }
1861 static const void* user_data() { return _user_data; }
1862 static GrowableArray<oop>* visit_stack() { return _visit_stack; }
1863
1864 // if the object hasn't been visited then push it onto the visit stack
1865 // so that it will be visited later
1866 static inline bool check_for_visit(oop obj) {
1867 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1868 return true;
1869 }
1870
1871 // invoke basic style callbacks
1872 static inline bool invoke_basic_heap_root_callback
1873 (jvmtiHeapRootKind root_kind, oop obj);
1874 static inline bool invoke_basic_stack_ref_callback
1875 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1876 int slot, oop obj);
1877 static inline bool invoke_basic_object_reference_callback
1878 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1879
1880 // invoke advanced style callbacks
1881 static inline bool invoke_advanced_heap_root_callback
1882 (jvmtiHeapReferenceKind ref_kind, oop obj);
1883 static inline bool invoke_advanced_stack_ref_callback
1884 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1885 jmethodID method, jlocation bci, jint slot, oop obj);
1886 static inline bool invoke_advanced_object_reference_callback
1887 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1888
1889 // used to report the value of primitive fields
1890 static inline bool report_primitive_field
1891 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1892
1893 public:
1894 // initialize for basic mode
1895 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1896 GrowableArray<oop>* visit_stack,
1897 const void* user_data,
1898 BasicHeapWalkContext context);
1899
1900 // initialize for advanced mode
1901 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1902 GrowableArray<oop>* visit_stack,
1903 const void* user_data,
1904 AdvancedHeapWalkContext context);
1905
1906 // functions to report roots
1907 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
1908 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1909 jmethodID m, oop o);
1910 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1911 jmethodID method, jlocation bci, jint slot, oop o);
1912
1913 // functions to report references
1914 static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
1915 static inline bool report_class_reference(oop referrer, oop referree);
1916 static inline bool report_class_loader_reference(oop referrer, oop referree);
1917 static inline bool report_signers_reference(oop referrer, oop referree);
1918 static inline bool report_protection_domain_reference(oop referrer, oop referree);
1919 static inline bool report_superclass_reference(oop referrer, oop referree);
1920 static inline bool report_interface_reference(oop referrer, oop referree);
1921 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
1922 static inline bool report_field_reference(oop referrer, oop referree, jint slot);
1923 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
1924 static inline bool report_primitive_array_values(oop array);
1925 static inline bool report_string_value(oop str);
1926 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
1927 static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
1928 };
1929
1930 // statics
1931 int CallbackInvoker::_heap_walk_type;
1932 BasicHeapWalkContext CallbackInvoker::_basic_context;
1933 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1934 JvmtiTagMap* CallbackInvoker::_tag_map;
1935 const void* CallbackInvoker::_user_data;
1936 GrowableArray<oop>* CallbackInvoker::_visit_stack;
1937
1938 // initialize for basic heap walk (IterateOverReachableObjects et al)
1939 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1940 GrowableArray<oop>* visit_stack,
1941 const void* user_data,
1942 BasicHeapWalkContext context) {
1943 _tag_map = tag_map;
1944 _visit_stack = visit_stack;
1945 _user_data = user_data;
1946 _basic_context = context;
1947 _advanced_context.invalidate(); // will trigger assertion if used
1948 _heap_walk_type = basic;
1949 }
1950
1951 // initialize for advanced heap walk (FollowReferences)
1952 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1953 GrowableArray<oop>* visit_stack,
1954 const void* user_data,
1955 AdvancedHeapWalkContext context) {
1956 _tag_map = tag_map;
1957 _visit_stack = visit_stack;
1958 _user_data = user_data;
1959 _advanced_context = context;
1960 _basic_context.invalidate(); // will trigger assertion if used
1961 _heap_walk_type = advanced;
1962 }
1963
1964
1965 // invoke basic style heap root callback
1966 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
1967 assert(ServiceUtil::visible_oop(obj), "checking");
1968
1969 // if we heap roots should be reported
1970 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1971 if (cb == NULL) {
1972 return check_for_visit(obj);
1973 }
1974
1975 CallbackWrapper wrapper(tag_map(), obj);
1976 jvmtiIterationControl control = (*cb)(root_kind,
1977 wrapper.klass_tag(),
1978 wrapper.obj_size(),
1979 wrapper.obj_tag_p(),
1980 (void*)user_data());
1981 // push root to visit stack when following references
1982 if (control == JVMTI_ITERATION_CONTINUE &&
1983 basic_context()->object_ref_callback() != NULL) {
1984 visit_stack()->push(obj);
1985 }
1986 return control != JVMTI_ITERATION_ABORT;
1987 }
1988
1989 // invoke basic style stack ref callback
1990 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
1991 jlong thread_tag,
1992 jint depth,
1993 jmethodID method,
1994 jint slot,
1995 oop obj) {
1996 assert(ServiceUtil::visible_oop(obj), "checking");
1997
1998 // if we stack refs should be reported
1999 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
2000 if (cb == NULL) {
2001 return check_for_visit(obj);
2002 }
2003
2004 CallbackWrapper wrapper(tag_map(), obj);
2005 jvmtiIterationControl control = (*cb)(root_kind,
2006 wrapper.klass_tag(),
2007 wrapper.obj_size(),
2008 wrapper.obj_tag_p(),
2009 thread_tag,
2010 depth,
2011 method,
2012 slot,
2013 (void*)user_data());
2014 // push root to visit stack when following references
2015 if (control == JVMTI_ITERATION_CONTINUE &&
2016 basic_context()->object_ref_callback() != NULL) {
2017 visit_stack()->push(obj);
2018 }
2019 return control != JVMTI_ITERATION_ABORT;
2020 }
2021
2022 // invoke basic style object reference callback
2023 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2024 oop referrer,
2025 oop referree,
2026 jint index) {
2027
2028 assert(ServiceUtil::visible_oop(referrer), "checking");
2029 assert(ServiceUtil::visible_oop(referree), "checking");
2030
2031 BasicHeapWalkContext* context = basic_context();
2032
2033 // callback requires the referrer's tag. If it's the same referrer
2034 // as the last call then we use the cached value.
2035 jlong referrer_tag;
2036 if (referrer == context->last_referrer()) {
2037 referrer_tag = context->last_referrer_tag();
2038 } else {
2039 referrer_tag = tag_for(tag_map(), referrer);
2040 }
2041
2042 // do the callback
2043 CallbackWrapper wrapper(tag_map(), referree);
2044 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2045 jvmtiIterationControl control = (*cb)(ref_kind,
2046 wrapper.klass_tag(),
2047 wrapper.obj_size(),
2048 wrapper.obj_tag_p(),
2049 referrer_tag,
2050 index,
2051 (void*)user_data());
2052
2053 // record referrer and referrer tag. For self-references record the
2054 // tag value from the callback as this might differ from referrer_tag.
2055 context->set_last_referrer(referrer);
2056 if (referrer == referree) {
2057 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2058 } else {
2059 context->set_last_referrer_tag(referrer_tag);
2060 }
2061
2062 if (control == JVMTI_ITERATION_CONTINUE) {
2063 return check_for_visit(referree);
2064 } else {
2065 return control != JVMTI_ITERATION_ABORT;
2066 }
2067 }
2068
2069 // invoke advanced style heap root callback
2070 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2071 oop obj) {
2072 assert(ServiceUtil::visible_oop(obj), "checking");
2073
2074 AdvancedHeapWalkContext* context = advanced_context();
2075
2076 // check that callback is provided
2077 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2078 if (cb == NULL) {
2079 return check_for_visit(obj);
2080 }
2081
2082 // apply class filter
2083 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2084 return check_for_visit(obj);
2085 }
2086
2087 // setup the callback wrapper
2088 CallbackWrapper wrapper(tag_map(), obj);
2089
2090 // apply tag filter
2091 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2092 wrapper.klass_tag(),
2093 context->heap_filter())) {
2094 return check_for_visit(obj);
2095 }
2096
2097 // for arrays we need the length, otherwise -1
2098 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2099
2100 // invoke the callback
2101 jint res = (*cb)(ref_kind,
2102 NULL, // referrer info
2103 wrapper.klass_tag(),
2104 0, // referrer_class_tag is 0 for heap root
2105 wrapper.obj_size(),
2106 wrapper.obj_tag_p(),
2107 NULL, // referrer_tag_p
2108 len,
2109 (void*)user_data());
2110 if (res & JVMTI_VISIT_ABORT) {
2111 return false;// referrer class tag
2112 }
2113 if (res & JVMTI_VISIT_OBJECTS) {
2114 check_for_visit(obj);
2115 }
2116 return true;
2117 }
2118
2119 // report a reference from a thread stack to an object
2120 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2121 jlong thread_tag,
2122 jlong tid,
2123 int depth,
2124 jmethodID method,
2125 jlocation bci,
2126 jint slot,
2127 oop obj) {
2128 assert(ServiceUtil::visible_oop(obj), "checking");
2129
2130 AdvancedHeapWalkContext* context = advanced_context();
2131
2132 // check that callback is provider
2133 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2134 if (cb == NULL) {
2135 return check_for_visit(obj);
2136 }
2137
2138 // apply class filter
2139 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2140 return check_for_visit(obj);
2141 }
2142
2143 // setup the callback wrapper
2144 CallbackWrapper wrapper(tag_map(), obj);
2145
2146 // apply tag filter
2147 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2148 wrapper.klass_tag(),
2149 context->heap_filter())) {
2150 return check_for_visit(obj);
2151 }
2152
2153 // setup the referrer info
2154 jvmtiHeapReferenceInfo reference_info;
2155 reference_info.stack_local.thread_tag = thread_tag;
2156 reference_info.stack_local.thread_id = tid;
2157 reference_info.stack_local.depth = depth;
2158 reference_info.stack_local.method = method;
2159 reference_info.stack_local.location = bci;
2160 reference_info.stack_local.slot = slot;
2161
2162 // for arrays we need the length, otherwise -1
2163 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2164
2165 // call into the agent
2166 int res = (*cb)(ref_kind,
2167 &reference_info,
2168 wrapper.klass_tag(),
2169 0, // referrer_class_tag is 0 for heap root (stack)
2170 wrapper.obj_size(),
2171 wrapper.obj_tag_p(),
2172 NULL, // referrer_tag is 0 for root
2173 len,
2174 (void*)user_data());
2175
2176 if (res & JVMTI_VISIT_ABORT) {
2177 return false;
2178 }
2179 if (res & JVMTI_VISIT_OBJECTS) {
2180 check_for_visit(obj);
2181 }
2182 return true;
2183 }
2184
2185 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2186 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2187 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2188 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2189 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2190 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2191 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2192 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2193
2194 // invoke the object reference callback to report a reference
2195 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2196 oop referrer,
2197 oop obj,
2198 jint index)
2199 {
2200 // field index is only valid field in reference_info
2201 static jvmtiHeapReferenceInfo reference_info = { 0 };
2202
2203 assert(ServiceUtil::visible_oop(referrer), "checking");
2204 assert(ServiceUtil::visible_oop(obj), "checking");
2205
2206 AdvancedHeapWalkContext* context = advanced_context();
2207
2208 // check that callback is provider
2209 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2210 if (cb == NULL) {
2211 return check_for_visit(obj);
2212 }
2213
2214 // apply class filter
2215 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2216 return check_for_visit(obj);
2217 }
2218
2219 // setup the callback wrapper
2220 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2221
2222 // apply tag filter
2223 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2224 wrapper.klass_tag(),
2225 context->heap_filter())) {
2226 return check_for_visit(obj);
2227 }
2228
2229 // field index is only valid field in reference_info
2230 reference_info.field.index = index;
2231
2232 // for arrays we need the length, otherwise -1
2233 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2234
2235 // invoke the callback
2236 int res = (*cb)(ref_kind,
2237 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2238 wrapper.klass_tag(),
2239 wrapper.referrer_klass_tag(),
2240 wrapper.obj_size(),
2241 wrapper.obj_tag_p(),
2242 wrapper.referrer_tag_p(),
2243 len,
2244 (void*)user_data());
2245
2246 if (res & JVMTI_VISIT_ABORT) {
2247 return false;
2248 }
2249 if (res & JVMTI_VISIT_OBJECTS) {
2250 check_for_visit(obj);
2251 }
2252 return true;
2253 }
2254
2255 // report a "simple root"
2256 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2257 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2258 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2259 assert(ServiceUtil::visible_oop(obj), "checking");
2260
2261 if (is_basic_heap_walk()) {
2262 // map to old style root kind
2263 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2264 return invoke_basic_heap_root_callback(root_kind, obj);
2265 } else {
2266 assert(is_advanced_heap_walk(), "wrong heap walk type");
2267 return invoke_advanced_heap_root_callback(kind, obj);
2268 }
2269 }
2270
2271
2272 // invoke the primitive array values
2273 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2274 assert(obj->is_typeArray(), "not a primitive array");
2275
2276 AdvancedHeapWalkContext* context = advanced_context();
2277 assert(context->array_primitive_value_callback() != NULL, "no callback");
2278
2279 // apply class filter
2280 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2281 return true;
2282 }
2283
2284 CallbackWrapper wrapper(tag_map(), obj);
2285
2286 // apply tag filter
2287 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2288 wrapper.klass_tag(),
2289 context->heap_filter())) {
2290 return true;
2291 }
2292
2293 // invoke the callback
2294 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2295 &wrapper,
2296 obj,
2297 (void*)user_data());
2298 return (!(res & JVMTI_VISIT_ABORT));
2299 }
2300
2301 // invoke the string value callback
2302 inline bool CallbackInvoker::report_string_value(oop str) {
2303 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2304
2305 AdvancedHeapWalkContext* context = advanced_context();
2306 assert(context->string_primitive_value_callback() != NULL, "no callback");
2307
2308 // apply class filter
2309 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2310 return true;
2311 }
2312
2313 CallbackWrapper wrapper(tag_map(), str);
2314
2315 // apply tag filter
2316 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2317 wrapper.klass_tag(),
2318 context->heap_filter())) {
2319 return true;
2320 }
2321
2322 // invoke the callback
2323 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2324 &wrapper,
2325 str,
2326 (void*)user_data());
2327 return (!(res & JVMTI_VISIT_ABORT));
2328 }
2329
2330 // invoke the primitive field callback
2331 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2332 oop obj,
2333 jint index,
2334 address addr,
2335 char type)
2336 {
2337 // for primitive fields only the index will be set
2338 static jvmtiHeapReferenceInfo reference_info = { 0 };
2339
2340 AdvancedHeapWalkContext* context = advanced_context();
2341 assert(context->primitive_field_callback() != NULL, "no callback");
2342
2343 // apply class filter
2344 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2345 return true;
2346 }
2347
2348 CallbackWrapper wrapper(tag_map(), obj);
2349
2350 // apply tag filter
2351 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2352 wrapper.klass_tag(),
2353 context->heap_filter())) {
2354 return true;
2355 }
2356
2357 // the field index in the referrer
2358 reference_info.field.index = index;
2359
2360 // map the type
2361 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2362
2363 // setup the jvalue
2364 jvalue value;
2365 copy_to_jvalue(&value, addr, value_type);
2366
2367 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2368 int res = (*cb)(ref_kind,
2369 &reference_info,
2370 wrapper.klass_tag(),
2371 wrapper.obj_tag_p(),
2372 value,
2373 value_type,
2374 (void*)user_data());
2375 return (!(res & JVMTI_VISIT_ABORT));
2376 }
2377
2378
2379 // instance field
2380 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2381 jint index,
2382 address value,
2383 char type) {
2384 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2385 obj,
2386 index,
2387 value,
2388 type);
2389 }
2390
2391 // static field
2392 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2393 jint index,
2394 address value,
2395 char type) {
2396 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2397 obj,
2398 index,
2399 value,
2400 type);
2401 }
2402
2403 // report a JNI local (root object) to the profiler
2404 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2405 if (is_basic_heap_walk()) {
2406 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2407 thread_tag,
2408 depth,
2409 m,
2410 -1,
2411 obj);
2412 } else {
2413 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2414 thread_tag, tid,
2415 depth,
2416 m,
2417 (jlocation)-1,
2418 -1,
2419 obj);
2420 }
2421 }
2422
2423
2424 // report a local (stack reference, root object)
2425 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2426 jlong tid,
2427 jint depth,
2428 jmethodID method,
2429 jlocation bci,
2430 jint slot,
2431 oop obj) {
2432 if (is_basic_heap_walk()) {
2433 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2434 thread_tag,
2435 depth,
2436 method,
2437 slot,
2438 obj);
2439 } else {
2440 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2441 thread_tag,
2442 tid,
2443 depth,
2444 method,
2445 bci,
2446 slot,
2447 obj);
2448 }
2449 }
2450
2451 // report an object referencing a class.
2452 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2453 if (is_basic_heap_walk()) {
2454 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2455 } else {
2456 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2457 }
2458 }
2459
2460 // report a class referencing its class loader.
2461 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2462 if (is_basic_heap_walk()) {
2463 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2464 } else {
2465 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2466 }
2467 }
2468
2469 // report a class referencing its signers.
2470 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2471 if (is_basic_heap_walk()) {
2472 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2473 } else {
2474 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2475 }
2476 }
2477
2478 // report a class referencing its protection domain..
2479 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2480 if (is_basic_heap_walk()) {
2481 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2482 } else {
2483 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2484 }
2485 }
2486
2487 // report a class referencing its superclass.
2488 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2489 if (is_basic_heap_walk()) {
2490 // Send this to be consistent with past implementation
2491 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2492 } else {
2493 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2494 }
2495 }
2496
2497 // report a class referencing one of its interfaces.
2498 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2499 if (is_basic_heap_walk()) {
2500 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2501 } else {
2502 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2503 }
2504 }
2505
2506 // report a class referencing one of its static fields.
2507 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2508 if (is_basic_heap_walk()) {
2509 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2510 } else {
2511 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2512 }
2513 }
2514
2515 // report an array referencing an element object
2516 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2517 if (is_basic_heap_walk()) {
2518 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2519 } else {
2520 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2521 }
2522 }
2523
2524 // report an object referencing an instance field object
2525 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2526 if (is_basic_heap_walk()) {
2527 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2528 } else {
2529 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2530 }
2531 }
2532
2533 // report an array referencing an element object
2534 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2535 if (is_basic_heap_walk()) {
2536 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2537 } else {
2538 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2539 }
2540 }
2541
2542 // A supporting closure used to process simple roots
2543 class SimpleRootsClosure : public OopClosure {
2544 private:
2545 jvmtiHeapReferenceKind _kind;
2546 bool _continue;
2547
2548 jvmtiHeapReferenceKind root_kind() { return _kind; }
2549
2550 public:
2551 void set_kind(jvmtiHeapReferenceKind kind) {
2552 _kind = kind;
2553 _continue = true;
2554 }
2555
2556 inline bool stopped() {
2557 return !_continue;
2558 }
2559
2560 void do_oop(oop* obj_p) {
2561 // iteration has terminated
2562 if (stopped()) {
2563 return;
2564 }
2565
2566 // ignore null or deleted handles
2567 oop o = *obj_p;
2568 if (o == NULL || o == JNIHandles::deleted_handle()) {
2569 return;
2570 }
2571
2572 assert(Universe::heap()->is_in_reserved(o), "should be impossible");
2573
2574 jvmtiHeapReferenceKind kind = root_kind();
2575 if (kind == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2576 // SystemDictionary::always_strong_oops_do reports the application
2577 // class loader as a root. We want this root to be reported as
2578 // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2579 if (!o->is_instanceMirror()) {
2580 kind = JVMTI_HEAP_REFERENCE_OTHER;
2581 }
2582 }
2583
2584 // some objects are ignored - in the case of simple
2585 // roots it's mostly Symbol*s that we are skipping
2586 // here.
2587 if (!ServiceUtil::visible_oop(o)) {
2588 return;
2589 }
2590
2591 // invoke the callback
2592 _continue = CallbackInvoker::report_simple_root(kind, o);
2593
2594 }
2595 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2596 };
2597
2598 // A supporting closure used to process JNI locals
2599 class JNILocalRootsClosure : public OopClosure {
2600 private:
2601 jlong _thread_tag;
2602 jlong _tid;
2603 jint _depth;
2604 jmethodID _method;
2605 bool _continue;
2606 public:
2607 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2608 _thread_tag = thread_tag;
2609 _tid = tid;
2610 _depth = depth;
2611 _method = method;
2612 _continue = true;
2613 }
2614
2615 inline bool stopped() {
2616 return !_continue;
2617 }
2618
2619 void do_oop(oop* obj_p) {
2620 // iteration has terminated
2621 if (stopped()) {
2622 return;
2623 }
2624
2625 // ignore null or deleted handles
2626 oop o = *obj_p;
2627 if (o == NULL || o == JNIHandles::deleted_handle()) {
2628 return;
2629 }
2630
2631 if (!ServiceUtil::visible_oop(o)) {
2632 return;
2633 }
2634
2635 // invoke the callback
2636 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2637 }
2638 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2639 };
2640
2641
2642 // A VM operation to iterate over objects that are reachable from
2643 // a set of roots or an initial object.
2644 //
2645 // For VM_HeapWalkOperation the set of roots used is :-
2646 //
2647 // - All JNI global references
2648 // - All inflated monitors
2649 // - All classes loaded by the boot class loader (or all classes
2650 // in the event that class unloading is disabled)
2651 // - All java threads
2652 // - For each java thread then all locals and JNI local references
2653 // on the thread's execution stack
2654 // - All visible/explainable objects from Universes::oops_do
2655 //
2656 class VM_HeapWalkOperation: public VM_Operation {
2657 private:
2658 enum {
2659 initial_visit_stack_size = 4000
2660 };
2661
2662 bool _is_advanced_heap_walk; // indicates FollowReferences
2663 JvmtiTagMap* _tag_map;
2664 Handle _initial_object;
2665 GrowableArray<oop>* _visit_stack; // the visit stack
2666
2667 bool _collecting_heap_roots; // are we collecting roots
2668 bool _following_object_refs; // are we following object references
2669
2670 bool _reporting_primitive_fields; // optional reporting
2671 bool _reporting_primitive_array_values;
2672 bool _reporting_string_values;
2673
2674 GrowableArray<oop>* create_visit_stack() {
2675 return new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(initial_visit_stack_size, true);
2676 }
2677
2678 // accessors
2679 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2680 JvmtiTagMap* tag_map() const { return _tag_map; }
2681 Handle initial_object() const { return _initial_object; }
2682
2683 bool is_following_references() const { return _following_object_refs; }
2684
2685 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2686 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2687 bool is_reporting_string_values() const { return _reporting_string_values; }
2688
2689 GrowableArray<oop>* visit_stack() const { return _visit_stack; }
2690
2691 // iterate over the various object types
2692 inline bool iterate_over_array(oop o);
2693 inline bool iterate_over_type_array(oop o);
2694 inline bool iterate_over_class(oop o);
2695 inline bool iterate_over_object(oop o);
2696
2697 // root collection
2698 inline bool collect_simple_roots();
2699 inline bool collect_stack_roots();
2700 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2701
2702 // visit an object
2703 inline bool visit(oop o);
2704
2705 public:
2706 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2707 Handle initial_object,
2708 BasicHeapWalkContext callbacks,
2709 const void* user_data);
2710
2711 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2712 Handle initial_object,
2713 AdvancedHeapWalkContext callbacks,
2714 const void* user_data);
2715
2716 ~VM_HeapWalkOperation();
2717
2718 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2719 void doit();
2720 };
2721
2722
2723 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2724 Handle initial_object,
2725 BasicHeapWalkContext callbacks,
2726 const void* user_data) {
2727 _is_advanced_heap_walk = false;
2728 _tag_map = tag_map;
2729 _initial_object = initial_object;
2730 _following_object_refs = (callbacks.object_ref_callback() != NULL);
2731 _reporting_primitive_fields = false;
2732 _reporting_primitive_array_values = false;
2733 _reporting_string_values = false;
2734 _visit_stack = create_visit_stack();
2735
2736
2737 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2738 }
2739
2740 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2741 Handle initial_object,
2742 AdvancedHeapWalkContext callbacks,
2743 const void* user_data) {
2744 _is_advanced_heap_walk = true;
2745 _tag_map = tag_map;
2746 _initial_object = initial_object;
2747 _following_object_refs = true;
2748 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2749 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2750 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2751 _visit_stack = create_visit_stack();
2752
2753 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2754 }
2755
2756 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2757 if (_following_object_refs) {
2758 assert(_visit_stack != NULL, "checking");
2759 delete _visit_stack;
2760 _visit_stack = NULL;
2761 }
2762 }
2763
2764 // an array references its class and has a reference to
2765 // each element in the array
2766 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2767 objArrayOop array = objArrayOop(o);
2768
2769 // array reference to its class
2770 oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
2771 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2772 return false;
2773 }
2774
2775 // iterate over the array and report each reference to a
2776 // non-null element
2777 for (int index=0; index<array->length(); index++) {
2778 oop elem = array->obj_at(index);
2779 if (elem == NULL) {
2780 continue;
2781 }
2782
2783 // report the array reference o[index] = elem
2784 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2785 return false;
2786 }
2787 }
2788 return true;
2789 }
2790
2791 // a type array references its class
2792 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2793 Klass* k = o->klass();
2794 oop mirror = k->java_mirror();
2795 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2796 return false;
2797 }
2798
2799 // report the array contents if required
2800 if (is_reporting_primitive_array_values()) {
2801 if (!CallbackInvoker::report_primitive_array_values(o)) {
2802 return false;
2803 }
2804 }
2805 return true;
2806 }
2807
2808 #ifdef ASSERT
2809 // verify that a static oop field is in range
2810 static inline bool verify_static_oop(InstanceKlass* ik,
2811 oop mirror, int offset) {
2812 address obj_p = (address)mirror + offset;
2813 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2814 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2815 assert(end >= start, "sanity check");
2816
2817 if (obj_p >= start && obj_p < end) {
2818 return true;
2819 } else {
2820 return false;
2821 }
2822 }
2823 #endif // #ifdef ASSERT
2824
2825 // a class references its super class, interfaces, class loader, ...
2826 // and finally its static fields
2827 inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) {
2828 int i;
2829 Klass* klass = java_lang_Class::as_Klass(java_class);
2830
2831 if (klass->oop_is_instance()) {
2832 InstanceKlass* ik = InstanceKlass::cast(klass);
2833
2834 // ignore the class if it's has been initialized yet
2835 if (!ik->is_linked()) {
2836 return true;
2837 }
2838
2839 // get the java mirror
2840 oop mirror = klass->java_mirror();
2841
2842 // super (only if something more interesting than java.lang.Object)
2843 Klass* java_super = ik->java_super();
2844 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2845 oop super = java_super->java_mirror();
2846 if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2847 return false;
2848 }
2849 }
2850
2851 // class loader
2852 oop cl = ik->class_loader();
2853 if (cl != NULL) {
2854 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2855 return false;
2856 }
2857 }
2858
2859 // protection domain
2860 oop pd = ik->protection_domain();
2861 if (pd != NULL) {
2862 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2863 return false;
2864 }
2865 }
2866
2867 // signers
2868 oop signers = ik->signers();
2869 if (signers != NULL) {
2870 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2871 return false;
2872 }
2873 }
2874
2875 // references from the constant pool
2876 {
2877 ConstantPool* pool = ik->constants();
2878 for (int i = 1; i < pool->length(); i++) {
2879 constantTag tag = pool->tag_at(i).value();
2880 if (tag.is_string() || tag.is_klass()) {
2881 oop entry;
2882 if (tag.is_string()) {
2883 entry = pool->resolved_string_at(i);
2884 // If the entry is non-null it is resolved.
2885 if (entry == NULL) continue;
2886 } else {
2887 entry = pool->resolved_klass_at(i)->java_mirror();
2888 }
2889 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2890 return false;
2891 }
2892 }
2893 }
2894 }
2895
2896 // interfaces
2897 // (These will already have been reported as references from the constant pool
2898 // but are specified by IterateOverReachableObjects and must be reported).
2899 Array<Klass*>* interfaces = ik->local_interfaces();
2900 for (i = 0; i < interfaces->length(); i++) {
2901 oop interf = ((Klass*)interfaces->at(i))->java_mirror();
2902 if (interf == NULL) {
2903 continue;
2904 }
2905 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
2906 return false;
2907 }
2908 }
2909
2910 // iterate over the static fields
2911
2912 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
2913 for (i=0; i<field_map->field_count(); i++) {
2914 ClassFieldDescriptor* field = field_map->field_at(i);
2915 char type = field->field_type();
2916 if (!is_primitive_field_type(type)) {
2917 oop fld_o = mirror->obj_field(field->field_offset());
2918 assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check");
2919 if (fld_o != NULL) {
2920 int slot = field->field_index();
2921 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
2922 delete field_map;
2923 return false;
2924 }
2925 }
2926 } else {
2927 if (is_reporting_primitive_fields()) {
2928 address addr = (address)mirror + field->field_offset();
2929 int slot = field->field_index();
2930 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
2931 delete field_map;
2932 return false;
2933 }
2934 }
2935 }
2936 }
2937 delete field_map;
2938
2939 return true;
2940 }
2941
2942 return true;
2943 }
2944
2945 // an object references a class and its instance fields
2946 // (static fields are ignored here as we report these as
2947 // references from the class).
2948 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
2949 // reference to the class
2950 if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) {
2951 return false;
2952 }
2953
2954 // iterate over instance fields
2955 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
2956 for (int i=0; i<field_map->field_count(); i++) {
2957 ClassFieldDescriptor* field = field_map->field_at(i);
2958 char type = field->field_type();
2959 if (!is_primitive_field_type(type)) {
2960 oop fld_o = o->obj_field(field->field_offset());
2961 // ignore any objects that aren't visible to profiler
2962 if (fld_o != NULL && ServiceUtil::visible_oop(fld_o)) {
2963 assert(Universe::heap()->is_in_reserved(fld_o), "unsafe code should not "
2964 "have references to Klass* anymore");
2965 int slot = field->field_index();
2966 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
2967 return false;
2968 }
2969 }
2970 } else {
2971 if (is_reporting_primitive_fields()) {
2972 // primitive instance field
2973 address addr = (address)o + field->field_offset();
2974 int slot = field->field_index();
2975 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
2976 return false;
2977 }
2978 }
2979 }
2980 }
2981
2982 // if the object is a java.lang.String
2983 if (is_reporting_string_values() &&
2984 o->klass() == SystemDictionary::String_klass()) {
2985 if (!CallbackInvoker::report_string_value(o)) {
2986 return false;
2987 }
2988 }
2989 return true;
2990 }
2991
2992
2993 // Collects all simple (non-stack) roots except for threads;
2994 // threads are handled in collect_stack_roots() as an optimization.
2995 // if there's a heap root callback provided then the callback is
2996 // invoked for each simple root.
2997 // if an object reference callback is provided then all simple
2998 // roots are pushed onto the marking stack so that they can be
2999 // processed later
3000 //
3001 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3002 SimpleRootsClosure blk;
3003
3004 // JNI globals
3005 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3006 JNIHandles::oops_do(&blk);
3007 if (blk.stopped()) {
3008 return false;
3009 }
3010
3011 // Preloaded classes and loader from the system dictionary
3012 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3013 SystemDictionary::always_strong_oops_do(&blk);
3014 KlassToOopClosure klass_blk(&blk);
3015 ClassLoaderDataGraph::always_strong_oops_do(&blk, &klass_blk, false);
3016 if (blk.stopped()) {
3017 return false;
3018 }
3019
3020 // Inflated monitors
3021 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3022 ObjectSynchronizer::oops_do(&blk);
3023 if (blk.stopped()) {
3024 return false;
3025 }
3026
3027 // threads are now handled in collect_stack_roots()
3028
3029 // Other kinds of roots maintained by HotSpot
3030 // Many of these won't be visible but others (such as instances of important
3031 // exceptions) will be visible.
3032 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3033 Universe::oops_do(&blk);
3034
3035 // If there are any non-perm roots in the code cache, visit them.
3036 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3037 CodeBlobToOopClosure look_in_blobs(&blk, !CodeBlobToOopClosure::FixRelocations);
3038 CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3039
3040 return true;
3041 }
3042
3043 // Walk the stack of a given thread and find all references (locals
3044 // and JNI calls) and report these as stack references
3045 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3046 JNILocalRootsClosure* blk)
3047 {
3048 oop threadObj = java_thread->threadObj();
3049 assert(threadObj != NULL, "sanity check");
3050
3051 // only need to get the thread's tag once per thread
3052 jlong thread_tag = tag_for(_tag_map, threadObj);
3053
3054 // also need the thread id
3055 jlong tid = java_lang_Thread::thread_id(threadObj);
3056
3057
3058 if (java_thread->has_last_Java_frame()) {
3059
3060 // vframes are resource allocated
3061 Thread* current_thread = Thread::current();
3062 ResourceMark rm(current_thread);
3063 HandleMark hm(current_thread);
3064
3065 RegisterMap reg_map(java_thread);
3066 frame f = java_thread->last_frame();
3067 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3068
3069 bool is_top_frame = true;
3070 int depth = 0;
3071 frame* last_entry_frame = NULL;
3072
3073 while (vf != NULL) {
3074 if (vf->is_java_frame()) {
3075
3076 // java frame (interpreted, compiled, ...)
3077 javaVFrame *jvf = javaVFrame::cast(vf);
3078
3079 // the jmethodID
3080 jmethodID method = jvf->method()->jmethod_id();
3081
3082 if (!(jvf->method()->is_native())) {
3083 jlocation bci = (jlocation)jvf->bci();
3084 StackValueCollection* locals = jvf->locals();
3085 for (int slot=0; slot<locals->size(); slot++) {
3086 if (locals->at(slot)->type() == T_OBJECT) {
3087 oop o = locals->obj_at(slot)();
3088 if (o == NULL) {
3089 continue;
3090 }
3091
3092 // stack reference
3093 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3094 bci, slot, o)) {
3095 return false;
3096 }
3097 }
3098 }
3099 } else {
3100 blk->set_context(thread_tag, tid, depth, method);
3101 if (is_top_frame) {
3102 // JNI locals for the top frame.
3103 java_thread->active_handles()->oops_do(blk);
3104 } else {
3105 if (last_entry_frame != NULL) {
3106 // JNI locals for the entry frame
3107 assert(last_entry_frame->is_entry_frame(), "checking");
3108 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3109 }
3110 }
3111 }
3112 last_entry_frame = NULL;
3113 depth++;
3114 } else {
3115 // externalVFrame - for an entry frame then we report the JNI locals
3116 // when we find the corresponding javaVFrame
3117 frame* fr = vf->frame_pointer();
3118 assert(fr != NULL, "sanity check");
3119 if (fr->is_entry_frame()) {
3120 last_entry_frame = fr;
3121 }
3122 }
3123
3124 vf = vf->sender();
3125 is_top_frame = false;
3126 }
3127 } else {
3128 // no last java frame but there may be JNI locals
3129 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3130 java_thread->active_handles()->oops_do(blk);
3131 }
3132 return true;
3133 }
3134
3135
3136 // Collects the simple roots for all threads and collects all
3137 // stack roots - for each thread it walks the execution
3138 // stack to find all references and local JNI refs.
3139 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3140 JNILocalRootsClosure blk;
3141 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3142 oop threadObj = thread->threadObj();
3143 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3144 // Collect the simple root for this thread before we
3145 // collect its stack roots
3146 if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD,
3147 threadObj)) {
3148 return false;
3149 }
3150 if (!collect_stack_roots(thread, &blk)) {
3151 return false;
3152 }
3153 }
3154 }
3155 return true;
3156 }
3157
3158 // visit an object
3159 // first mark the object as visited
3160 // second get all the outbound references from this object (in other words, all
3161 // the objects referenced by this object).
3162 //
3163 bool VM_HeapWalkOperation::visit(oop o) {
3164 // mark object as visited
3165 assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3166 ObjectMarker::mark(o);
3167
3168 // instance
3169 if (o->is_instance()) {
3170 if (o->klass() == SystemDictionary::Class_klass()) {
3171 if (!java_lang_Class::is_primitive(o)) {
3172 // a java.lang.Class
3173 return iterate_over_class(o);
3174 }
3175 } else {
3176 return iterate_over_object(o);
3177 }
3178 }
3179
3180 // object array
3181 if (o->is_objArray()) {
3182 return iterate_over_array(o);
3183 }
3184
3185 // type array
3186 if (o->is_typeArray()) {
3187 return iterate_over_type_array(o);
3188 }
3189
3190 return true;
3191 }
3192
3193 void VM_HeapWalkOperation::doit() {
3194 ResourceMark rm;
3195 ObjectMarkerController marker;
3196 ClassFieldMapCacheMark cm;
3197
3198 assert(visit_stack()->is_empty(), "visit stack must be empty");
3199
3200 // the heap walk starts with an initial object or the heap roots
3201 if (initial_object().is_null()) {
3202 // If either collect_stack_roots() or collect_simple_roots()
3203 // returns false at this point, then there are no mark bits
3204 // to reset.
3205 ObjectMarker::set_needs_reset(false);
3206
3207 // Calling collect_stack_roots() before collect_simple_roots()
3208 // can result in a big performance boost for an agent that is
3209 // focused on analyzing references in the thread stacks.
3210 if (!collect_stack_roots()) return;
3211
3212 if (!collect_simple_roots()) return;
3213
3214 // no early return so enable heap traversal to reset the mark bits
3215 ObjectMarker::set_needs_reset(true);
3216 } else {
3217 visit_stack()->push(initial_object()());
3218 }
3219
3220 // object references required
3221 if (is_following_references()) {
3222
3223 // visit each object until all reachable objects have been
3224 // visited or the callback asked to terminate the iteration.
3225 while (!visit_stack()->is_empty()) {
3226 oop o = visit_stack()->pop();
3227 if (!ObjectMarker::visited(o)) {
3228 if (!visit(o)) {
3229 break;
3230 }
3231 }
3232 }
3233 }
3234 }
3235
3236 // iterate over all objects that are reachable from a set of roots
3237 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3238 jvmtiStackReferenceCallback stack_ref_callback,
3239 jvmtiObjectReferenceCallback object_ref_callback,
3240 const void* user_data) {
3241 MutexLocker ml(Heap_lock);
3242 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3243 VM_HeapWalkOperation op(this, Handle(), context, user_data);
3244 VMThread::execute(&op);
3245 }
3246
3247 // iterate over all objects that are reachable from a given object
3248 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3249 jvmtiObjectReferenceCallback object_ref_callback,
3250 const void* user_data) {
3251 oop obj = JNIHandles::resolve(object);
3252 Handle initial_object(Thread::current(), obj);
3253
3254 MutexLocker ml(Heap_lock);
3255 BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3256 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3257 VMThread::execute(&op);
3258 }
3259
3260 // follow references from an initial object or the GC roots
3261 void JvmtiTagMap::follow_references(jint heap_filter,
3262 KlassHandle klass,
3263 jobject object,
3264 const jvmtiHeapCallbacks* callbacks,
3265 const void* user_data)
3266 {
3267 oop obj = JNIHandles::resolve(object);
3268 Handle initial_object(Thread::current(), obj);
3269
3270 MutexLocker ml(Heap_lock);
3271 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3272 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3273 VMThread::execute(&op);
3274 }
3275
3276
3277 void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
3278 // No locks during VM bring-up (0 threads) and no safepoints after main
3279 // thread creation and before VMThread creation (1 thread); initial GC
3280 // verification can happen in that window which gets to here.
3281 assert(Threads::number_of_threads() <= 1 ||
3282 SafepointSynchronize::is_at_safepoint(),
3283 "must be executed at a safepoint");
3284 if (JvmtiEnv::environments_might_exist()) {
3285 JvmtiEnvIterator it;
3286 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3287 JvmtiTagMap* tag_map = env->tag_map_acquire();
3288 if (tag_map != NULL && !tag_map->is_empty()) {
3289 tag_map->do_weak_oops(is_alive, f);
3290 }
3291 }
3292 }
3293 }
3294
3295 void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
3296
3297 // does this environment have the OBJECT_FREE event enabled
3298 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3299
3300 // counters used for trace message
3301 int freed = 0;
3302 int moved = 0;
3303
3304 JvmtiTagHashmap* hashmap = this->hashmap();
3305
3306 // reenable sizing (if disabled)
3307 hashmap->set_resizing_enabled(true);
3308
3309 // if the hashmap is empty then we can skip it
3310 if (hashmap->_entry_count == 0) {
3311 return;
3312 }
3313
3314 // now iterate through each entry in the table
3315
3316 JvmtiTagHashmapEntry** table = hashmap->table();
3317 int size = hashmap->size();
3318
3319 JvmtiTagHashmapEntry* delayed_add = NULL;
3320
3321 for (int pos = 0; pos < size; ++pos) {
3322 JvmtiTagHashmapEntry* entry = table[pos];
3323 JvmtiTagHashmapEntry* prev = NULL;
3324
3325 while (entry != NULL) {
3326 JvmtiTagHashmapEntry* next = entry->next();
3327
3328 oop* obj = entry->object_addr();
3329
3330 // has object been GC'ed
3331 if (!is_alive->do_object_b(entry->object())) {
3332 // grab the tag
3333 jlong tag = entry->tag();
3334 guarantee(tag != 0, "checking");
3335
3336 // remove GC'ed entry from hashmap and return the
3337 // entry to the free list
3338 hashmap->remove(prev, pos, entry);
3339 destroy_entry(entry);
3340
3341 // post the event to the profiler
3342 if (post_object_free) {
3343 JvmtiExport::post_object_free(env(), tag);
3344 }
3345
3346 ++freed;
3347 } else {
3348 f->do_oop(entry->object_addr());
3349 oop new_oop = entry->object();
3350
3351 // if the object has moved then re-hash it and move its
3352 // entry to its new location.
3353 unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
3354 if (new_pos != (unsigned int)pos) {
3355 if (prev == NULL) {
3356 table[pos] = next;
3357 } else {
3358 prev->set_next(next);
3359 }
3360 if (new_pos < (unsigned int)pos) {
3361 entry->set_next(table[new_pos]);
3362 table[new_pos] = entry;
3363 } else {
3364 // Delay adding this entry to it's new position as we'd end up
3365 // hitting it again during this iteration.
3366 entry->set_next(delayed_add);
3367 delayed_add = entry;
3368 }
3369 moved++;
3370 } else {
3371 // object didn't move
3372 prev = entry;
3373 }
3374 }
3375
3376 entry = next;
3377 }
3378 }
3379
3380 // Re-add all the entries which were kept aside
3381 while (delayed_add != NULL) {
3382 JvmtiTagHashmapEntry* next = delayed_add->next();
3383 unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
3384 delayed_add->set_next(table[pos]);
3385 table[pos] = delayed_add;
3386 delayed_add = next;
3387 }
3388
3389 // stats
3390 if (TraceJVMTIObjectTagging) {
3391 int post_total = hashmap->_entry_count;
3392 int pre_total = post_total + freed;
3393
3394 tty->print_cr("(%d->%d, %d freed, %d total moves)",
3395 pre_total, post_total, freed, moved);
3396 }
3397 }