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