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