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