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