1 /*
2 * Copyright (c) 2003, 2009, 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 "incls/_precompiled.incl"
26 # include "incls/_jvmtiTagMap.cpp.incl"
27
28 // JvmtiTagHashmapEntry
29 //
30 // Each entry encapsulates a JNI weak reference to the tagged object
31 // and the tag value. In addition an entry includes a next pointer which
32 // is used to chain entries together.
33
34 class JvmtiTagHashmapEntry : public CHeapObj {
35 private:
36 friend class JvmtiTagMap;
37
38 jweak _object; // JNI weak ref to tagged object
39 jlong _tag; // the tag
40 JvmtiTagHashmapEntry* _next; // next on the list
41
42 inline void init(jweak object, jlong tag) {
43 _object = object;
44 _tag = tag;
45 _next = NULL;
46 }
47
48 // constructor
49 JvmtiTagHashmapEntry(jweak object, jlong tag) { init(object, tag); }
50
51 public:
52
53 // accessor methods
54 inline jweak object() const { return _object; }
55 inline jlong tag() const { return _tag; }
56
57 inline void set_tag(jlong tag) {
58 assert(tag != 0, "can't be zero");
59 _tag = tag;
60 }
61
62 inline JvmtiTagHashmapEntry* next() const { return _next; }
63 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; }
64 };
65
66
67 // JvmtiTagHashmap
68 //
69 // A hashmap is essentially a table of pointers to entries. Entries
70 // are hashed to a location, or position in the table, and then
71 // chained from that location. The "key" for hashing is address of
72 // the object, or oop. The "value" is the JNI weak reference to the
73 // object and the tag value. Keys are not stored with the entry.
74 // Instead the weak reference is resolved to obtain the key.
75 //
76 // A hashmap maintains a count of the number entries in the hashmap
77 // and resizes if the number of entries exceeds a given threshold.
78 // The threshold is specified as a percentage of the size - for
79 // example a threshold of 0.75 will trigger the hashmap to resize
80 // if the number of entries is >75% of table size.
81 //
82 // A hashmap provides functions for adding, removing, and finding
83 // entries. It also provides a function to iterate over all entries
84 // in the hashmap.
85
86 class JvmtiTagHashmap : public CHeapObj {
87 private:
88 friend class JvmtiTagMap;
89
90 enum {
91 small_trace_threshold = 10000, // threshold for tracing
92 medium_trace_threshold = 100000,
93 large_trace_threshold = 1000000,
94 initial_trace_threshold = small_trace_threshold
95 };
96
97 static int _sizes[]; // array of possible hashmap sizes
98 int _size; // actual size of the table
99 int _size_index; // index into size table
100
101 int _entry_count; // number of entries in the hashmap
102
103 float _load_factor; // load factor as a % of the size
104 int _resize_threshold; // computed threshold to trigger resizing.
105 bool _resizing_enabled; // indicates if hashmap can resize
106
107 int _trace_threshold; // threshold for trace messages
108
109 JvmtiTagHashmapEntry** _table; // the table of entries.
110
111 // private accessors
112 int resize_threshold() const { return _resize_threshold; }
113 int trace_threshold() const { return _trace_threshold; }
114
115 // initialize the hashmap
116 void init(int size_index=0, float load_factor=4.0f) {
117 int initial_size = _sizes[size_index];
118 _size_index = size_index;
119 _size = initial_size;
120 _entry_count = 0;
121 if (TraceJVMTIObjectTagging) {
122 _trace_threshold = initial_trace_threshold;
123 } else {
124 _trace_threshold = -1;
125 }
126 _load_factor = load_factor;
127 _resize_threshold = (int)(_load_factor * _size);
128 _resizing_enabled = true;
129 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
130 _table = (JvmtiTagHashmapEntry**)os::malloc(s);
131 if (_table == NULL) {
132 vm_exit_out_of_memory(s, "unable to allocate initial hashtable for jvmti object tags");
133 }
134 for (int i=0; i<initial_size; i++) {
135 _table[i] = NULL;
136 }
137 }
138
139 // hash a given key (oop) with the specified size
140 static unsigned int hash(oop key, int size) {
141 // shift right to get better distribution (as these bits will be zero
142 // with aligned addresses)
143 unsigned int addr = (unsigned int)((intptr_t)key);
144 #ifdef _LP64
145 return (addr >> 3) % size;
146 #else
147 return (addr >> 2) % size;
148 #endif
149 }
150
151 // hash a given key (oop)
152 unsigned int hash(oop key) {
153 return hash(key, _size);
154 }
155
156 // resize the hashmap - allocates a large table and re-hashes
157 // all entries into the new table.
158 void resize() {
159 int new_size_index = _size_index+1;
160 int new_size = _sizes[new_size_index];
161 if (new_size < 0) {
162 // hashmap already at maximum capacity
163 return;
164 }
165
166 // allocate new table
167 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
168 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s);
169 if (new_table == NULL) {
170 warning("unable to allocate larger hashtable for jvmti object tags");
171 set_resizing_enabled(false);
172 return;
173 }
174
175 // initialize new table
176 int i;
177 for (i=0; i<new_size; i++) {
178 new_table[i] = NULL;
179 }
180
181 // rehash all entries into the new table
182 for (i=0; i<_size; i++) {
183 JvmtiTagHashmapEntry* entry = _table[i];
184 while (entry != NULL) {
185 JvmtiTagHashmapEntry* next = entry->next();
186 oop key = JNIHandles::resolve(entry->object());
187 assert(key != NULL, "jni weak reference cleared!!");
188 unsigned int h = hash(key, new_size);
189 JvmtiTagHashmapEntry* anchor = new_table[h];
190 if (anchor == NULL) {
191 new_table[h] = entry;
192 entry->set_next(NULL);
193 } else {
194 entry->set_next(anchor);
195 new_table[h] = entry;
196 }
197 entry = next;
198 }
199 }
200
201 // free old table and update settings.
202 os::free((void*)_table);
203 _table = new_table;
204 _size_index = new_size_index;
205 _size = new_size;
206
207 // compute new resize threshold
208 _resize_threshold = (int)(_load_factor * _size);
209 }
210
211
212 // internal remove function - remove an entry at a given position in the
213 // table.
214 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
215 assert(pos >= 0 && pos < _size, "out of range");
216 if (prev == NULL) {
217 _table[pos] = entry->next();
218 } else {
219 prev->set_next(entry->next());
220 }
221 assert(_entry_count > 0, "checking");
222 _entry_count--;
223 }
224
225 // resizing switch
226 bool is_resizing_enabled() const { return _resizing_enabled; }
227 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; }
228
229 // debugging
230 void print_memory_usage();
231 void compute_next_trace_threshold();
232
233 public:
234
235 // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
236 // The preferred size is rounded down to an actual size.
237 JvmtiTagHashmap(int size, float load_factor=0.0f) {
238 int i=0;
239 while (_sizes[i] < size) {
240 if (_sizes[i] < 0) {
241 assert(i > 0, "sanity check");
242 i--;
243 break;
244 }
245 i++;
246 }
247
248 // if a load factor is specified then use it, otherwise use default
249 if (load_factor > 0.01f) {
250 init(i, load_factor);
251 } else {
252 init(i);
253 }
254 }
255
256 // create a JvmtiTagHashmap with default settings
257 JvmtiTagHashmap() {
258 init();
259 }
260
261 // release table when JvmtiTagHashmap destroyed
262 ~JvmtiTagHashmap() {
263 if (_table != NULL) {
264 os::free((void*)_table);
265 _table = NULL;
266 }
267 }
268
269 // accessors
270 int size() const { return _size; }
271 JvmtiTagHashmapEntry** table() const { return _table; }
272 int entry_count() const { return _entry_count; }
273
274 // find an entry in the hashmap, returns NULL if not found.
275 inline JvmtiTagHashmapEntry* find(oop key) {
276 unsigned int h = hash(key);
277 JvmtiTagHashmapEntry* entry = _table[h];
278 while (entry != NULL) {
279 oop orig_key = JNIHandles::resolve(entry->object());
280 assert(orig_key != NULL, "jni weak reference cleared!!");
281 if (key == orig_key) {
282 break;
283 }
284 entry = entry->next();
285 }
286 return entry;
287 }
288
289
290 // add a new entry to hashmap
291 inline void add(oop key, JvmtiTagHashmapEntry* entry) {
292 assert(key != NULL, "checking");
293 assert(find(key) == NULL, "duplicate detected");
294 unsigned int h = hash(key);
295 JvmtiTagHashmapEntry* anchor = _table[h];
296 if (anchor == NULL) {
297 _table[h] = entry;
298 entry->set_next(NULL);
299 } else {
300 entry->set_next(anchor);
301 _table[h] = entry;
302 }
303
304 _entry_count++;
305 if (trace_threshold() > 0 && entry_count() >= trace_threshold()) {
306 assert(TraceJVMTIObjectTagging, "should only get here when tracing");
307 print_memory_usage();
308 compute_next_trace_threshold();
309 }
310
311 // if the number of entries exceed the threshold then resize
312 if (entry_count() > resize_threshold() && is_resizing_enabled()) {
313 resize();
314 }
315 }
316
317 // remove an entry with the given key.
318 inline JvmtiTagHashmapEntry* remove(oop key) {
319 unsigned int h = hash(key);
320 JvmtiTagHashmapEntry* entry = _table[h];
321 JvmtiTagHashmapEntry* prev = NULL;
322 while (entry != NULL) {
323 oop orig_key = JNIHandles::resolve(entry->object());
324 assert(orig_key != NULL, "jni weak reference cleared!!");
325 if (key == orig_key) {
326 break;
327 }
328 prev = entry;
329 entry = entry->next();
330 }
331 if (entry != NULL) {
332 remove(prev, h, entry);
333 }
334 return entry;
335 }
336
337 // iterate over all entries in the hashmap
338 void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
339 };
340
341 // possible hashmap sizes - odd primes that roughly double in size.
342 // To avoid excessive resizing the odd primes from 4801-76831 and
343 // 76831-307261 have been removed. The list must be terminated by -1.
344 int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891,
345 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
346
347
348 // A supporting class for iterating over all entries in Hashmap
349 class JvmtiTagHashmapEntryClosure {
350 public:
351 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
352 };
353
354
355 // iterate over all entries in the hashmap
356 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
357 for (int i=0; i<_size; i++) {
358 JvmtiTagHashmapEntry* entry = _table[i];
359 JvmtiTagHashmapEntry* prev = NULL;
360 while (entry != NULL) {
361 // obtain the next entry before invoking do_entry - this is
362 // necessary because do_entry may remove the entry from the
363 // hashmap.
364 JvmtiTagHashmapEntry* next = entry->next();
365 closure->do_entry(entry);
366 entry = next;
367 }
368 }
369 }
370
371 // debugging
372 void JvmtiTagHashmap::print_memory_usage() {
373 intptr_t p = (intptr_t)this;
374 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
375
376 // table + entries in KB
377 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
378 entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
379
380 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
381 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
382 entry_count(), hashmap_usage, weak_globals_usage);
383 }
384
385 // compute threshold for the next trace message
386 void JvmtiTagHashmap::compute_next_trace_threshold() {
387 if (trace_threshold() < medium_trace_threshold) {
388 _trace_threshold += small_trace_threshold;
389 } else {
390 if (trace_threshold() < large_trace_threshold) {
391 _trace_threshold += medium_trace_threshold;
392 } else {
393 _trace_threshold += large_trace_threshold;
394 }
395 }
396 }
397
398 // memory region for young generation
399 MemRegion JvmtiTagMap::_young_gen;
400
401 // get the memory region used for the young generation
402 void JvmtiTagMap::get_young_generation() {
403 CollectedHeap* ch = Universe::heap();
404 switch (ch->kind()) {
405 case (CollectedHeap::GenCollectedHeap): {
406 _young_gen = ((GenCollectedHeap*)ch)->get_gen(0)->reserved();
407 break;
408 }
409 #ifndef SERIALGC
410 case (CollectedHeap::ParallelScavengeHeap): {
411 _young_gen = ((ParallelScavengeHeap*)ch)->young_gen()->reserved();
412 break;
413 }
414 case (CollectedHeap::G1CollectedHeap): {
415 // Until a more satisfactory solution is implemented, all
416 // oops in the tag map will require rehash at each gc.
417 // This is a correct, if extremely inefficient solution.
418 // See RFE 6621729 for related commentary.
419 _young_gen = ch->reserved_region();
420 break;
421 }
422 #endif // !SERIALGC
423 default:
424 ShouldNotReachHere();
425 }
426 }
427
428 // returns true if oop is in the young generation
429 inline bool JvmtiTagMap::is_in_young(oop o) {
430 assert(_young_gen.start() != NULL, "checking");
431 void* p = (void*)o;
432 bool in_young = _young_gen.contains(p);
433 return in_young;
434 }
435
436 // returns the appropriate hashmap for a given object
437 inline JvmtiTagHashmap* JvmtiTagMap::hashmap_for(oop o) {
438 if (is_in_young(o)) {
439 return _hashmap[0];
440 } else {
441 return _hashmap[1];
442 }
443 }
444
445
446 // create a JvmtiTagMap
447 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
448 _env(env),
449 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
450 _free_entries(NULL),
451 _free_entries_count(0)
452 {
453 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
454 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
455
456 // create the hashmaps
457 for (int i=0; i<n_hashmaps; i++) {
458 _hashmap[i] = new JvmtiTagHashmap();
459 }
460
461 // get the memory region used by the young generation
462 get_young_generation();
463
464 // finally add us to the environment
465 ((JvmtiEnvBase *)env)->set_tag_map(this);
466 }
467
468
469 // destroy a JvmtiTagMap
470 JvmtiTagMap::~JvmtiTagMap() {
471
472 // no lock acquired as we assume the enclosing environment is
473 // also being destroryed.
474 ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
475
476 // iterate over the hashmaps and destroy each of the entries
477 for (int i=0; i<n_hashmaps; i++) {
478 JvmtiTagHashmap* hashmap = _hashmap[i];
479 JvmtiTagHashmapEntry** table = hashmap->table();
480 for (int j=0; j<hashmap->size(); j++) {
481 JvmtiTagHashmapEntry *entry = table[j];
482 while (entry != NULL) {
483 JvmtiTagHashmapEntry* next = entry->next();
484 jweak ref = entry->object();
485 JNIHandles::destroy_weak_global(ref);
486 delete entry;
487 entry = next;
488 }
489 }
490
491 // finally destroy the hashmap
492 delete hashmap;
493 }
494
495 // remove any entries on the free list
496 JvmtiTagHashmapEntry* entry = _free_entries;
497 while (entry != NULL) {
498 JvmtiTagHashmapEntry* next = entry->next();
499 delete entry;
500 entry = next;
501 }
502 }
503
504 // create a hashmap entry
505 // - if there's an entry on the (per-environment) free list then this
506 // is returned. Otherwise an new entry is allocated.
507 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(jweak ref, jlong tag) {
508 assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
509 JvmtiTagHashmapEntry* entry;
510 if (_free_entries == NULL) {
511 entry = new JvmtiTagHashmapEntry(ref, tag);
512 } else {
513 assert(_free_entries_count > 0, "mismatched _free_entries_count");
514 _free_entries_count--;
515 entry = _free_entries;
516 _free_entries = entry->next();
517 entry->init(ref, tag);
518 }
519 return entry;
520 }
521
522 // destroy an entry by returning it to the free list
523 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
524 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
525 // limit the size of the free list
526 if (_free_entries_count >= max_free_entries) {
527 delete entry;
528 } else {
529 entry->set_next(_free_entries);
530 _free_entries = entry;
531 _free_entries_count++;
532 }
533 }
534
535 // returns the tag map for the given environments. If the tag map
536 // doesn't exist then it is created.
537 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
538 JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map();
539 if (tag_map == NULL) {
540 MutexLocker mu(JvmtiThreadState_lock);
541 tag_map = ((JvmtiEnvBase *)env)->tag_map();
542 if (tag_map == NULL) {
543 tag_map = new JvmtiTagMap(env);
544 }
545 } else {
546 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
547 }
548 return tag_map;
549 }
550
551 // iterate over all entries in the tag map.
552 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
553 for (int i=0; i<n_hashmaps; i++) {
554 JvmtiTagHashmap* hashmap = _hashmap[i];
555 hashmap->entry_iterate(closure);
556 }
557 }
558
559 // returns true if the hashmaps are empty
560 bool JvmtiTagMap::is_empty() {
561 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
562 assert(n_hashmaps == 2, "not implemented");
563 return ((_hashmap[0]->entry_count() == 0) && (_hashmap[1]->entry_count() == 0));
564 }
565
566
567 // Return the tag value for an object, or 0 if the object is
568 // not tagged
569 //
570 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
571 JvmtiTagHashmapEntry* entry = tag_map->hashmap_for(o)->find(o);
572 if (entry == NULL) {
573 return 0;
574 } else {
575 return entry->tag();
576 }
577 }
578
579 // If the object is a java.lang.Class then return the klassOop,
580 // otherwise return the original object
581 static inline oop klassOop_if_java_lang_Class(oop o) {
582 if (o->klass() == SystemDictionary::Class_klass()) {
583 if (!java_lang_Class::is_primitive(o)) {
584 o = (oop)java_lang_Class::as_klassOop(o);
585 assert(o != NULL, "class for non-primitive mirror must exist");
586 }
587 }
588 return o;
589 }
590
591 // A CallbackWrapper is a support class for querying and tagging an object
592 // around a callback to a profiler. The constructor does pre-callback
593 // work to get the tag value, klass tag value, ... and the destructor
594 // does the post-callback work of tagging or untagging the object.
595 //
596 // {
597 // CallbackWrapper wrapper(tag_map, o);
598 //
599 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
600 //
601 // } // wrapper goes out of scope here which results in the destructor
602 // checking to see if the object has been tagged, untagged, or the
603 // tag value has changed.
604 //
605 class CallbackWrapper : public StackObj {
606 private:
607 JvmtiTagMap* _tag_map;
608 JvmtiTagHashmap* _hashmap;
609 JvmtiTagHashmapEntry* _entry;
610 oop _o;
611 jlong _obj_size;
612 jlong _obj_tag;
613 klassOop _klass; // the object's class
614 jlong _klass_tag;
615
616 protected:
617 JvmtiTagMap* tag_map() const { return _tag_map; }
618
619 // invoked post-callback to tag, untag, or update the tag of an object
620 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
621 JvmtiTagHashmapEntry* entry, jlong obj_tag);
622 public:
623 CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
624 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
625 "MT unsafe or must be VM thread");
626
627 // for Classes the klassOop is tagged
628 _o = klassOop_if_java_lang_Class(o);
629
630 // object size
631 _obj_size = _o->size() * wordSize;
632
633 // record the context
634 _tag_map = tag_map;
635 _hashmap = tag_map->hashmap_for(_o);
636 _entry = _hashmap->find(_o);
637
638 // get object tag
639 _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
640
641 // get the class and the class's tag value
642 if (_o == o) {
643 _klass = _o->klass();
644 } else {
645 // if the object represents a runtime class then use the
646 // tag for java.lang.Class
647 _klass = SystemDictionary::Class_klass();
648 }
649 _klass_tag = tag_for(tag_map, _klass);
650 }
651
652 ~CallbackWrapper() {
653 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
654 }
655
656 inline jlong* obj_tag_p() { return &_obj_tag; }
657 inline jlong obj_size() const { return _obj_size; }
658 inline jlong obj_tag() const { return _obj_tag; }
659 inline klassOop klass() const { return _klass; }
660 inline jlong klass_tag() const { return _klass_tag; }
661 };
662
663
664
665 // callback post-callback to tag, untag, or update the tag of an object
666 void inline CallbackWrapper::post_callback_tag_update(oop o,
667 JvmtiTagHashmap* hashmap,
668 JvmtiTagHashmapEntry* entry,
669 jlong obj_tag) {
670 if (entry == NULL) {
671 if (obj_tag != 0) {
672 // callback has tagged the object
673 assert(Thread::current()->is_VM_thread(), "must be VMThread");
674 HandleMark hm;
675 Handle h(o);
676 jweak ref = JNIHandles::make_weak_global(h);
677 entry = tag_map()->create_entry(ref, obj_tag);
678 hashmap->add(o, entry);
679 }
680 } else {
681 // object was previously tagged - the callback may have untagged
682 // the object or changed the tag value
683 if (obj_tag == 0) {
684 jweak ref = entry->object();
685
686 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
687 assert(entry_removed == entry, "checking");
688 tag_map()->destroy_entry(entry);
689
690 JNIHandles::destroy_weak_global(ref);
691 } else {
692 if (obj_tag != entry->tag()) {
693 entry->set_tag(obj_tag);
694 }
695 }
696 }
697 }
698
699 // An extended CallbackWrapper used when reporting an object reference
700 // to the agent.
701 //
702 // {
703 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
704 //
705 // (*callback)(wrapper.klass_tag(),
706 // wrapper.obj_size(),
707 // wrapper.obj_tag_p()
708 // wrapper.referrer_tag_p(), ...)
709 //
710 // } // wrapper goes out of scope here which results in the destructor
711 // checking to see if the referrer object has been tagged, untagged,
712 // or the tag value has changed.
713 //
714 class TwoOopCallbackWrapper : public CallbackWrapper {
715 private:
716 bool _is_reference_to_self;
717 JvmtiTagHashmap* _referrer_hashmap;
718 JvmtiTagHashmapEntry* _referrer_entry;
719 oop _referrer;
720 jlong _referrer_obj_tag;
721 jlong _referrer_klass_tag;
722 jlong* _referrer_tag_p;
723
724 bool is_reference_to_self() const { return _is_reference_to_self; }
725
726 public:
727 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
728 CallbackWrapper(tag_map, o)
729 {
730 // self reference needs to be handled in a special way
731 _is_reference_to_self = (referrer == o);
732
733 if (_is_reference_to_self) {
734 _referrer_klass_tag = klass_tag();
735 _referrer_tag_p = obj_tag_p();
736 } else {
737 // for Classes the klassOop is tagged
738 _referrer = klassOop_if_java_lang_Class(referrer);
739 // record the context
740 _referrer_hashmap = tag_map->hashmap_for(_referrer);
741 _referrer_entry = _referrer_hashmap->find(_referrer);
742
743 // get object tag
744 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
745 _referrer_tag_p = &_referrer_obj_tag;
746
747 // get referrer class tag.
748 klassOop k = (_referrer == referrer) ? // Check if referrer is a class...
749 _referrer->klass() // No, just get its class
750 : SystemDictionary::Class_klass(); // Yes, its class is Class
751 _referrer_klass_tag = tag_for(tag_map, k);
752 }
753 }
754
755 ~TwoOopCallbackWrapper() {
756 if (!is_reference_to_self()){
757 post_callback_tag_update(_referrer,
758 _referrer_hashmap,
759 _referrer_entry,
760 _referrer_obj_tag);
761 }
762 }
763
764 // address of referrer tag
765 // (for a self reference this will return the same thing as obj_tag_p())
766 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
767
768 // referrer's class tag
769 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
770 };
771
772 // tag an object
773 //
774 // This function is performance critical. If many threads attempt to tag objects
775 // around the same time then it's possible that the Mutex associated with the
776 // tag map will be a hot lock. Eliminating this lock will not eliminate the issue
777 // because creating a JNI weak reference requires acquiring a global lock also.
778 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
779 MutexLocker ml(lock());
780
781 // resolve the object
782 oop o = JNIHandles::resolve_non_null(object);
783
784 // for Classes we tag the klassOop
785 o = klassOop_if_java_lang_Class(o);
786
787 // see if the object is already tagged
788 JvmtiTagHashmap* hashmap = hashmap_for(o);
789 JvmtiTagHashmapEntry* entry = hashmap->find(o);
790
791 // if the object is not already tagged then we tag it
792 if (entry == NULL) {
793 if (tag != 0) {
794 HandleMark hm;
795 Handle h(o);
796 jweak ref = JNIHandles::make_weak_global(h);
797
798 // the object may have moved because make_weak_global may
799 // have blocked - thus it is necessary resolve the handle
800 // and re-hash the object.
801 o = h();
802 entry = create_entry(ref, tag);
803 hashmap_for(o)->add(o, entry);
804 } else {
805 // no-op
806 }
807 } else {
808 // if the object is already tagged then we either update
809 // the tag (if a new tag value has been provided)
810 // or remove the object if the new tag value is 0.
811 // Removing the object requires that we also delete the JNI
812 // weak ref to the object.
813 if (tag == 0) {
814 jweak ref = entry->object();
815 hashmap->remove(o);
816 destroy_entry(entry);
817 JNIHandles::destroy_weak_global(ref);
818 } else {
819 entry->set_tag(tag);
820 }
821 }
822 }
823
824 // get the tag for an object
825 jlong JvmtiTagMap::get_tag(jobject object) {
826 MutexLocker ml(lock());
827
828 // resolve the object
829 oop o = JNIHandles::resolve_non_null(object);
830
831 // for Classes get the tag from the klassOop
832 return tag_for(this, klassOop_if_java_lang_Class(o));
833 }
834
835
836 // Helper class used to describe the static or instance fields of a class.
837 // For each field it holds the field index (as defined by the JVMTI specification),
838 // the field type, and the offset.
839
840 class ClassFieldDescriptor: public CHeapObj {
841 private:
842 int _field_index;
843 int _field_offset;
844 char _field_type;
845 public:
846 ClassFieldDescriptor(int index, char type, int offset) :
847 _field_index(index), _field_type(type), _field_offset(offset) {
848 }
849 int field_index() const { return _field_index; }
850 char field_type() const { return _field_type; }
851 int field_offset() const { return _field_offset; }
852 };
853
854 class ClassFieldMap: public CHeapObj {
855 private:
856 enum {
857 initial_field_count = 5
858 };
859
860 // list of field descriptors
861 GrowableArray<ClassFieldDescriptor*>* _fields;
862
863 // constructor
864 ClassFieldMap();
865
866 // add a field
867 void add(int index, char type, int offset);
868
869 // returns the field count for the given class
870 static int compute_field_count(instanceKlassHandle ikh);
871
872 public:
873 ~ClassFieldMap();
874
875 // access
876 int field_count() { return _fields->length(); }
877 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
878
879 // functions to create maps of static or instance fields
880 static ClassFieldMap* create_map_of_static_fields(klassOop k);
881 static ClassFieldMap* create_map_of_instance_fields(oop obj);
882 };
883
884 ClassFieldMap::ClassFieldMap() {
885 _fields = new (ResourceObj::C_HEAP) GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
886 }
887
888 ClassFieldMap::~ClassFieldMap() {
889 for (int i=0; i<_fields->length(); i++) {
890 delete _fields->at(i);
891 }
892 delete _fields;
893 }
894
895 void ClassFieldMap::add(int index, char type, int offset) {
896 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
897 _fields->append(field);
898 }
899
900 // Returns a heap allocated ClassFieldMap to describe the static fields
901 // of the given class.
902 //
903 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(klassOop k) {
904 HandleMark hm;
905 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
906
907 // create the field map
908 ClassFieldMap* field_map = new ClassFieldMap();
909
910 FilteredFieldStream f(ikh, false, false);
911 int max_field_index = f.field_count()-1;
912
913 int index = 0;
914 for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
915 // ignore instance fields
916 if (!fld.access_flags().is_static()) {
917 continue;
918 }
919 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
920 }
921 return field_map;
922 }
923
924 // Returns a heap allocated ClassFieldMap to describe the instance fields
925 // of the given class. All instance fields are included (this means public
926 // and private fields declared in superclasses and superinterfaces too).
927 //
928 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
929 HandleMark hm;
930 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
931
932 // create the field map
933 ClassFieldMap* field_map = new ClassFieldMap();
934
935 FilteredFieldStream f(ikh, false, false);
936
937 int max_field_index = f.field_count()-1;
938
939 int index = 0;
940 for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
941 // ignore static fields
942 if (fld.access_flags().is_static()) {
943 continue;
944 }
945 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
946 }
947
948 return field_map;
949 }
950
951 // Helper class used to cache a ClassFileMap for the instance fields of
952 // a cache. A JvmtiCachedClassFieldMap can be cached by an instanceKlass during
953 // heap iteration and avoid creating a field map for each object in the heap
954 // (only need to create the map when the first instance of a class is encountered).
955 //
956 class JvmtiCachedClassFieldMap : public CHeapObj {
957 private:
958 enum {
959 initial_class_count = 200
960 };
961 ClassFieldMap* _field_map;
962
963 ClassFieldMap* field_map() const { return _field_map; }
964
965 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
966 ~JvmtiCachedClassFieldMap();
967
968 static GrowableArray<instanceKlass*>* _class_list;
969 static void add_to_class_list(instanceKlass* ik);
970
971 public:
972 // returns the field map for a given object (returning map cached
973 // by instanceKlass if possible
974 static ClassFieldMap* get_map_of_instance_fields(oop obj);
975
976 // removes the field map from all instanceKlasses - should be
977 // called before VM operation completes
978 static void clear_cache();
979
980 // returns the number of ClassFieldMap cached by instanceKlasses
981 static int cached_field_map_count();
982 };
983
984 GrowableArray<instanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
985
986 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
987 _field_map = field_map;
988 }
989
990 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
991 if (_field_map != NULL) {
992 delete _field_map;
993 }
994 }
995
996 // Marker class to ensure that the class file map cache is only used in a defined
997 // scope.
998 class ClassFieldMapCacheMark : public StackObj {
999 private:
1000 static bool _is_active;
1001 public:
1002 ClassFieldMapCacheMark() {
1003 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1004 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
1005 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
1006 _is_active = true;
1007 }
1008 ~ClassFieldMapCacheMark() {
1009 JvmtiCachedClassFieldMap::clear_cache();
1010 _is_active = false;
1011 }
1012 static bool is_active() { return _is_active; }
1013 };
1014
1015 bool ClassFieldMapCacheMark::_is_active;
1016
1017
1018 // record that the given instanceKlass is caching a field map
1019 void JvmtiCachedClassFieldMap::add_to_class_list(instanceKlass* ik) {
1020 if (_class_list == NULL) {
1021 _class_list = new (ResourceObj::C_HEAP) GrowableArray<instanceKlass*>(initial_class_count, true);
1022 }
1023 _class_list->push(ik);
1024 }
1025
1026 // returns the instance field map for the given object
1027 // (returns field map cached by the instanceKlass if possible)
1028 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
1029 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1030 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
1031
1032 klassOop k = obj->klass();
1033 instanceKlass* ik = instanceKlass::cast(k);
1034
1035 // return cached map if possible
1036 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
1037 if (cached_map != NULL) {
1038 assert(cached_map->field_map() != NULL, "missing field list");
1039 return cached_map->field_map();
1040 } else {
1041 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
1042 cached_map = new JvmtiCachedClassFieldMap(field_map);
1043 ik->set_jvmti_cached_class_field_map(cached_map);
1044 add_to_class_list(ik);
1045 return field_map;
1046 }
1047 }
1048
1049 // remove the fields maps cached from all instanceKlasses
1050 void JvmtiCachedClassFieldMap::clear_cache() {
1051 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1052 if (_class_list != NULL) {
1053 for (int i = 0; i < _class_list->length(); i++) {
1054 instanceKlass* ik = _class_list->at(i);
1055 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
1056 assert(cached_map != NULL, "should not be NULL");
1057 ik->set_jvmti_cached_class_field_map(NULL);
1058 delete cached_map; // deletes the encapsulated field map
1059 }
1060 delete _class_list;
1061 _class_list = NULL;
1062 }
1063 }
1064
1065 // returns the number of ClassFieldMap cached by instanceKlasses
1066 int JvmtiCachedClassFieldMap::cached_field_map_count() {
1067 return (_class_list == NULL) ? 0 : _class_list->length();
1068 }
1069
1070 // helper function to indicate if an object is filtered by its tag or class tag
1071 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
1072 jlong klass_tag,
1073 int heap_filter) {
1074 // apply the heap filter
1075 if (obj_tag != 0) {
1076 // filter out tagged objects
1077 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
1078 } else {
1079 // filter out untagged objects
1080 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
1081 }
1082 if (klass_tag != 0) {
1083 // filter out objects with tagged classes
1084 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1085 } else {
1086 // filter out objects with untagged classes.
1087 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1088 }
1089 return false;
1090 }
1091
1092 // helper function to indicate if an object is filtered by a klass filter
1093 static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
1094 if (!klass_filter.is_null()) {
1095 if (obj->klass() != klass_filter()) {
1096 return true;
1097 }
1098 }
1099 return false;
1100 }
1101
1102 // helper function to tell if a field is a primitive field or not
1103 static inline bool is_primitive_field_type(char type) {
1104 return (type != 'L' && type != '[');
1105 }
1106
1107 // helper function to copy the value from location addr to jvalue.
1108 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1109 switch (value_type) {
1110 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1111 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
1112 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
1113 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
1114 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
1115 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
1116 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
1117 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
1118 default: ShouldNotReachHere();
1119 }
1120 }
1121
1122 // helper function to invoke string primitive value callback
1123 // returns visit control flags
1124 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1125 CallbackWrapper* wrapper,
1126 oop str,
1127 void* user_data)
1128 {
1129 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1130
1131 // get the string value and length
1132 // (string value may be offset from the base)
1133 int s_len = java_lang_String::length(str);
1134 typeArrayOop s_value = java_lang_String::value(str);
1135 int s_offset = java_lang_String::offset(str);
1136 jchar* value;
1137 if (s_len > 0) {
1138 value = s_value->char_at_addr(s_offset);
1139 } else {
1140 value = (jchar*) s_value->base(T_CHAR);
1141 }
1142
1143 // invoke the callback
1144 return (*cb)(wrapper->klass_tag(),
1145 wrapper->obj_size(),
1146 wrapper->obj_tag_p(),
1147 value,
1148 (jint)s_len,
1149 user_data);
1150 }
1151
1152 // helper function to invoke string primitive value callback
1153 // returns visit control flags
1154 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1155 CallbackWrapper* wrapper,
1156 oop obj,
1157 void* user_data)
1158 {
1159 assert(obj->is_typeArray(), "not a primitive array");
1160
1161 // get base address of first element
1162 typeArrayOop array = typeArrayOop(obj);
1163 BasicType type = typeArrayKlass::cast(array->klass())->element_type();
1164 void* elements = array->base(type);
1165
1166 // jvmtiPrimitiveType is defined so this mapping is always correct
1167 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1168
1169 return (*cb)(wrapper->klass_tag(),
1170 wrapper->obj_size(),
1171 wrapper->obj_tag_p(),
1172 (jint)array->length(),
1173 elem_type,
1174 elements,
1175 user_data);
1176 }
1177
1178 // helper function to invoke the primitive field callback for all static fields
1179 // of a given class
1180 static jint invoke_primitive_field_callback_for_static_fields
1181 (CallbackWrapper* wrapper,
1182 oop obj,
1183 jvmtiPrimitiveFieldCallback cb,
1184 void* user_data)
1185 {
1186 // for static fields only the index will be set
1187 static jvmtiHeapReferenceInfo reference_info = { 0 };
1188
1189 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1190 if (java_lang_Class::is_primitive(obj)) {
1191 return 0;
1192 }
1193 klassOop k = java_lang_Class::as_klassOop(obj);
1194 Klass* klass = k->klass_part();
1195
1196 // ignore classes for object and type arrays
1197 if (!klass->oop_is_instance()) {
1198 return 0;
1199 }
1200
1201 // ignore classes which aren't linked yet
1202 instanceKlass* ik = instanceKlass::cast(k);
1203 if (!ik->is_linked()) {
1204 return 0;
1205 }
1206
1207 // get the field map
1208 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
1209
1210 // invoke the callback for each static primitive field
1211 for (int i=0; i<field_map->field_count(); i++) {
1212 ClassFieldDescriptor* field = field_map->field_at(i);
1213
1214 // ignore non-primitive fields
1215 char type = field->field_type();
1216 if (!is_primitive_field_type(type)) {
1217 continue;
1218 }
1219 // one-to-one mapping
1220 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1221
1222 // get offset and field value
1223 int offset = field->field_offset();
1224 address addr = (address)k + offset;
1225 jvalue value;
1226 copy_to_jvalue(&value, addr, value_type);
1227
1228 // field index
1229 reference_info.field.index = field->field_index();
1230
1231 // invoke the callback
1232 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1233 &reference_info,
1234 wrapper->klass_tag(),
1235 wrapper->obj_tag_p(),
1236 value,
1237 value_type,
1238 user_data);
1239 if (res & JVMTI_VISIT_ABORT) {
1240 delete field_map;
1241 return res;
1242 }
1243 }
1244
1245 delete field_map;
1246 return 0;
1247 }
1248
1249 // helper function to invoke the primitive field callback for all instance fields
1250 // of a given object
1251 static jint invoke_primitive_field_callback_for_instance_fields(
1252 CallbackWrapper* wrapper,
1253 oop obj,
1254 jvmtiPrimitiveFieldCallback cb,
1255 void* user_data)
1256 {
1257 // for instance fields only the index will be set
1258 static jvmtiHeapReferenceInfo reference_info = { 0 };
1259
1260 // get the map of the instance fields
1261 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1262
1263 // invoke the callback for each instance primitive field
1264 for (int i=0; i<fields->field_count(); i++) {
1265 ClassFieldDescriptor* field = fields->field_at(i);
1266
1267 // ignore non-primitive fields
1268 char type = field->field_type();
1269 if (!is_primitive_field_type(type)) {
1270 continue;
1271 }
1272 // one-to-one mapping
1273 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1274
1275 // get offset and field value
1276 int offset = field->field_offset();
1277 address addr = (address)obj + offset;
1278 jvalue value;
1279 copy_to_jvalue(&value, addr, value_type);
1280
1281 // field index
1282 reference_info.field.index = field->field_index();
1283
1284 // invoke the callback
1285 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1286 &reference_info,
1287 wrapper->klass_tag(),
1288 wrapper->obj_tag_p(),
1289 value,
1290 value_type,
1291 user_data);
1292 if (res & JVMTI_VISIT_ABORT) {
1293 return res;
1294 }
1295 }
1296 return 0;
1297 }
1298
1299
1300 // VM operation to iterate over all objects in the heap (both reachable
1301 // and unreachable)
1302 class VM_HeapIterateOperation: public VM_Operation {
1303 private:
1304 ObjectClosure* _blk;
1305 public:
1306 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1307
1308 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1309 void doit() {
1310 // allows class files maps to be cached during iteration
1311 ClassFieldMapCacheMark cm;
1312
1313 // make sure that heap is parsable (fills TLABs with filler objects)
1314 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1315
1316 // Verify heap before iteration - if the heap gets corrupted then
1317 // JVMTI's IterateOverHeap will crash.
1318 if (VerifyBeforeIteration) {
1319 Universe::verify();
1320 }
1321
1322 // do the iteration
1323 // If this operation encounters a bad object when using CMS,
1324 // consider using safe_object_iterate() which avoids perm gen
1325 // objects that may contain bad references.
1326 Universe::heap()->object_iterate(_blk);
1327
1328 // when sharing is enabled we must iterate over the shared spaces
1329 if (UseSharedSpaces) {
1330 GenCollectedHeap* gch = GenCollectedHeap::heap();
1331 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
1332 gen->ro_space()->object_iterate(_blk);
1333 gen->rw_space()->object_iterate(_blk);
1334 }
1335 }
1336
1337 };
1338
1339
1340 // An ObjectClosure used to support the deprecated IterateOverHeap and
1341 // IterateOverInstancesOfClass functions
1342 class IterateOverHeapObjectClosure: public ObjectClosure {
1343 private:
1344 JvmtiTagMap* _tag_map;
1345 KlassHandle _klass;
1346 jvmtiHeapObjectFilter _object_filter;
1347 jvmtiHeapObjectCallback _heap_object_callback;
1348 const void* _user_data;
1349
1350 // accessors
1351 JvmtiTagMap* tag_map() const { return _tag_map; }
1352 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1353 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1354 KlassHandle klass() const { return _klass; }
1355 const void* user_data() const { return _user_data; }
1356
1357 // indicates if iteration has been aborted
1358 bool _iteration_aborted;
1359 bool is_iteration_aborted() const { return _iteration_aborted; }
1360 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1361
1362 public:
1363 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1364 KlassHandle klass,
1365 jvmtiHeapObjectFilter object_filter,
1366 jvmtiHeapObjectCallback heap_object_callback,
1367 const void* user_data) :
1368 _tag_map(tag_map),
1369 _klass(klass),
1370 _object_filter(object_filter),
1371 _heap_object_callback(heap_object_callback),
1372 _user_data(user_data),
1373 _iteration_aborted(false)
1374 {
1375 }
1376
1377 void do_object(oop o);
1378 };
1379
1380 // invoked for each object in the heap
1381 void IterateOverHeapObjectClosure::do_object(oop o) {
1382 // check if iteration has been halted
1383 if (is_iteration_aborted()) return;
1384
1385 // ignore any objects that aren't visible to profiler
1386 if (!ServiceUtil::visible_oop(o)) return;
1387
1388 // instanceof check when filtering by klass
1389 if (!klass().is_null() && !o->is_a(klass()())) {
1390 return;
1391 }
1392 // prepare for the calllback
1393 CallbackWrapper wrapper(tag_map(), o);
1394
1395 // if the object is tagged and we're only interested in untagged objects
1396 // then don't invoke the callback. Similiarly, if the object is untagged
1397 // and we're only interested in tagged objects we skip the callback.
1398 if (wrapper.obj_tag() != 0) {
1399 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1400 } else {
1401 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1402 }
1403
1404 // invoke the agent's callback
1405 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1406 wrapper.obj_size(),
1407 wrapper.obj_tag_p(),
1408 (void*)user_data());
1409 if (control == JVMTI_ITERATION_ABORT) {
1410 set_iteration_aborted(true);
1411 }
1412 }
1413
1414 // An ObjectClosure used to support the IterateThroughHeap function
1415 class IterateThroughHeapObjectClosure: public ObjectClosure {
1416 private:
1417 JvmtiTagMap* _tag_map;
1418 KlassHandle _klass;
1419 int _heap_filter;
1420 const jvmtiHeapCallbacks* _callbacks;
1421 const void* _user_data;
1422
1423 // accessor functions
1424 JvmtiTagMap* tag_map() const { return _tag_map; }
1425 int heap_filter() const { return _heap_filter; }
1426 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1427 KlassHandle klass() const { return _klass; }
1428 const void* user_data() const { return _user_data; }
1429
1430 // indicates if the iteration has been aborted
1431 bool _iteration_aborted;
1432 bool is_iteration_aborted() const { return _iteration_aborted; }
1433
1434 // used to check the visit control flags. If the abort flag is set
1435 // then we set the iteration aborted flag so that the iteration completes
1436 // without processing any further objects
1437 bool check_flags_for_abort(jint flags) {
1438 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1439 if (is_abort) {
1440 _iteration_aborted = true;
1441 }
1442 return is_abort;
1443 }
1444
1445 public:
1446 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1447 KlassHandle klass,
1448 int heap_filter,
1449 const jvmtiHeapCallbacks* heap_callbacks,
1450 const void* user_data) :
1451 _tag_map(tag_map),
1452 _klass(klass),
1453 _heap_filter(heap_filter),
1454 _callbacks(heap_callbacks),
1455 _user_data(user_data),
1456 _iteration_aborted(false)
1457 {
1458 }
1459
1460 void do_object(oop o);
1461 };
1462
1463 // invoked for each object in the heap
1464 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1465 // check if iteration has been halted
1466 if (is_iteration_aborted()) return;
1467
1468 // ignore any objects that aren't visible to profiler
1469 if (!ServiceUtil::visible_oop(obj)) return;
1470
1471 // apply class filter
1472 if (is_filtered_by_klass_filter(obj, klass())) return;
1473
1474 // prepare for callback
1475 CallbackWrapper wrapper(tag_map(), obj);
1476
1477 // check if filtered by the heap filter
1478 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1479 return;
1480 }
1481
1482 // for arrays we need the length, otherwise -1
1483 bool is_array = obj->is_array();
1484 int len = is_array ? arrayOop(obj)->length() : -1;
1485
1486 // invoke the object callback (if callback is provided)
1487 if (callbacks()->heap_iteration_callback != NULL) {
1488 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1489 jint res = (*cb)(wrapper.klass_tag(),
1490 wrapper.obj_size(),
1491 wrapper.obj_tag_p(),
1492 (jint)len,
1493 (void*)user_data());
1494 if (check_flags_for_abort(res)) return;
1495 }
1496
1497 // for objects and classes we report primitive fields if callback provided
1498 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1499 jint res;
1500 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1501 if (obj->klass() == SystemDictionary::Class_klass()) {
1502 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1503 obj,
1504 cb,
1505 (void*)user_data());
1506 } else {
1507 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1508 obj,
1509 cb,
1510 (void*)user_data());
1511 }
1512 if (check_flags_for_abort(res)) return;
1513 }
1514
1515 // string callback
1516 if (!is_array &&
1517 callbacks()->string_primitive_value_callback != NULL &&
1518 obj->klass() == SystemDictionary::String_klass()) {
1519 jint res = invoke_string_value_callback(
1520 callbacks()->string_primitive_value_callback,
1521 &wrapper,
1522 obj,
1523 (void*)user_data() );
1524 if (check_flags_for_abort(res)) return;
1525 }
1526
1527 // array callback
1528 if (is_array &&
1529 callbacks()->array_primitive_value_callback != NULL &&
1530 obj->is_typeArray()) {
1531 jint res = invoke_array_primitive_value_callback(
1532 callbacks()->array_primitive_value_callback,
1533 &wrapper,
1534 obj,
1535 (void*)user_data() );
1536 if (check_flags_for_abort(res)) return;
1537 }
1538 };
1539
1540
1541 // Deprecated function to iterate over all objects in the heap
1542 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1543 KlassHandle klass,
1544 jvmtiHeapObjectCallback heap_object_callback,
1545 const void* user_data)
1546 {
1547 MutexLocker ml(Heap_lock);
1548 IterateOverHeapObjectClosure blk(this,
1549 klass,
1550 object_filter,
1551 heap_object_callback,
1552 user_data);
1553 VM_HeapIterateOperation op(&blk);
1554 VMThread::execute(&op);
1555 }
1556
1557
1558 // Iterates over all objects in the heap
1559 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1560 KlassHandle klass,
1561 const jvmtiHeapCallbacks* callbacks,
1562 const void* user_data)
1563 {
1564 MutexLocker ml(Heap_lock);
1565 IterateThroughHeapObjectClosure blk(this,
1566 klass,
1567 heap_filter,
1568 callbacks,
1569 user_data);
1570 VM_HeapIterateOperation op(&blk);
1571 VMThread::execute(&op);
1572 }
1573
1574 // support class for get_objects_with_tags
1575
1576 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1577 private:
1578 JvmtiEnv* _env;
1579 jlong* _tags;
1580 jint _tag_count;
1581
1582 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1583 GrowableArray<uint64_t>* _tag_results; // collected tags
1584
1585 public:
1586 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1587 _env = env;
1588 _tags = (jlong*)tags;
1589 _tag_count = tag_count;
1590 _object_results = new (ResourceObj::C_HEAP) GrowableArray<jobject>(1,true);
1591 _tag_results = new (ResourceObj::C_HEAP) GrowableArray<uint64_t>(1,true);
1592 }
1593
1594 ~TagObjectCollector() {
1595 delete _object_results;
1596 delete _tag_results;
1597 }
1598
1599 // for each tagged object check if the tag value matches
1600 // - if it matches then we create a JNI local reference to the object
1601 // and record the reference and tag value.
1602 //
1603 void do_entry(JvmtiTagHashmapEntry* entry) {
1604 for (int i=0; i<_tag_count; i++) {
1605 if (_tags[i] == entry->tag()) {
1606 oop o = JNIHandles::resolve(entry->object());
1607 assert(o != NULL && o != JNIHandles::deleted_handle(), "sanity check");
1608
1609 // the mirror is tagged
1610 if (o->is_klass()) {
1611 klassOop k = (klassOop)o;
1612 o = Klass::cast(k)->java_mirror();
1613 }
1614
1615 jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1616 _object_results->append(ref);
1617 _tag_results->append((uint64_t)entry->tag());
1618 }
1619 }
1620 }
1621
1622 // return the results from the collection
1623 //
1624 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1625 jvmtiError error;
1626 int count = _object_results->length();
1627 assert(count >= 0, "sanity check");
1628
1629 // if object_result_ptr is not NULL then allocate the result and copy
1630 // in the object references.
1631 if (object_result_ptr != NULL) {
1632 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1633 if (error != JVMTI_ERROR_NONE) {
1634 return error;
1635 }
1636 for (int i=0; i<count; i++) {
1637 (*object_result_ptr)[i] = _object_results->at(i);
1638 }
1639 }
1640
1641 // if tag_result_ptr is not NULL then allocate the result and copy
1642 // in the tag values.
1643 if (tag_result_ptr != NULL) {
1644 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1645 if (error != JVMTI_ERROR_NONE) {
1646 if (object_result_ptr != NULL) {
1647 _env->Deallocate((unsigned char*)object_result_ptr);
1648 }
1649 return error;
1650 }
1651 for (int i=0; i<count; i++) {
1652 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1653 }
1654 }
1655
1656 *count_ptr = count;
1657 return JVMTI_ERROR_NONE;
1658 }
1659 };
1660
1661 // return the list of objects with the specified tags
1662 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1663 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1664
1665 TagObjectCollector collector(env(), tags, count);
1666 {
1667 // iterate over all tagged objects
1668 MutexLocker ml(lock());
1669 entry_iterate(&collector);
1670 }
1671 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1672 }
1673
1674
1675 // ObjectMarker is used to support the marking objects when walking the
1676 // heap.
1677 //
1678 // This implementation uses the existing mark bits in an object for
1679 // marking. Objects that are marked must later have their headers restored.
1680 // As most objects are unlocked and don't have their identity hash computed
1681 // we don't have to save their headers. Instead we save the headers that
1682 // are "interesting". Later when the headers are restored this implementation
1683 // restores all headers to their initial value and then restores the few
1684 // objects that had interesting headers.
1685 //
1686 // Future work: This implementation currently uses growable arrays to save
1687 // the oop and header of interesting objects. As an optimization we could
1688 // use the same technique as the GC and make use of the unused area
1689 // between top() and end().
1690 //
1691
1692 // An ObjectClosure used to restore the mark bits of an object
1693 class RestoreMarksClosure : public ObjectClosure {
1694 public:
1695 void do_object(oop o) {
1696 if (o != NULL) {
1697 markOop mark = o->mark();
1698 if (mark->is_marked()) {
1699 o->init_mark();
1700 }
1701 }
1702 }
1703 };
1704
1705 // ObjectMarker provides the mark and visited functions
1706 class ObjectMarker : AllStatic {
1707 private:
1708 // saved headers
1709 static GrowableArray<oop>* _saved_oop_stack;
1710 static GrowableArray<markOop>* _saved_mark_stack;
1711
1712 public:
1713 static void init(); // initialize
1714 static void done(); // clean-up
1715
1716 static inline void mark(oop o); // mark an object
1717 static inline bool visited(oop o); // check if object has been visited
1718 };
1719
1720 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1721 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1722
1723 // initialize ObjectMarker - prepares for object marking
1724 void ObjectMarker::init() {
1725 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1726
1727 // prepare heap for iteration
1728 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1729
1730 // create stacks for interesting headers
1731 _saved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(4000, true);
1732 _saved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
1733
1734 if (UseBiasedLocking) {
1735 BiasedLocking::preserve_marks();
1736 }
1737 }
1738
1739 // Object marking is done so restore object headers
1740 void ObjectMarker::done() {
1741 // iterate over all objects and restore the mark bits to
1742 // their initial value
1743 RestoreMarksClosure blk;
1744 Universe::heap()->object_iterate(&blk);
1745
1746 // When sharing is enabled we need to restore the headers of the objects
1747 // in the readwrite space too.
1748 if (UseSharedSpaces) {
1749 GenCollectedHeap* gch = GenCollectedHeap::heap();
1750 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
1751 gen->rw_space()->object_iterate(&blk);
1752 }
1753
1754 // now restore the interesting headers
1755 for (int i = 0; i < _saved_oop_stack->length(); i++) {
1756 oop o = _saved_oop_stack->at(i);
1757 markOop mark = _saved_mark_stack->at(i);
1758 o->set_mark(mark);
1759 }
1760
1761 if (UseBiasedLocking) {
1762 BiasedLocking::restore_marks();
1763 }
1764
1765 // free the stacks
1766 delete _saved_oop_stack;
1767 delete _saved_mark_stack;
1768 }
1769
1770 // mark an object
1771 inline void ObjectMarker::mark(oop o) {
1772 assert(Universe::heap()->is_in(o), "sanity check");
1773 assert(!o->mark()->is_marked(), "should only mark an object once");
1774
1775 // object's mark word
1776 markOop mark = o->mark();
1777
1778 if (mark->must_be_preserved(o)) {
1779 _saved_mark_stack->push(mark);
1780 _saved_oop_stack->push(o);
1781 }
1782
1783 // mark the object
1784 o->set_mark(markOopDesc::prototype()->set_marked());
1785 }
1786
1787 // return true if object is marked
1788 inline bool ObjectMarker::visited(oop o) {
1789 return o->mark()->is_marked();
1790 }
1791
1792 // Stack allocated class to help ensure that ObjectMarker is used
1793 // correctly. Constructor initializes ObjectMarker, destructor calls
1794 // ObjectMarker's done() function to restore object headers.
1795 class ObjectMarkerController : public StackObj {
1796 public:
1797 ObjectMarkerController() {
1798 ObjectMarker::init();
1799 }
1800 ~ObjectMarkerController() {
1801 ObjectMarker::done();
1802 }
1803 };
1804
1805
1806 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1807 // (not performance critical as only used for roots)
1808 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1809 switch (kind) {
1810 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1811 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1812 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR;
1813 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1814 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1815 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1816 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1817 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1818 }
1819 }
1820
1821 // Base class for all heap walk contexts. The base class maintains a flag
1822 // to indicate if the context is valid or not.
1823 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1824 private:
1825 bool _valid;
1826 public:
1827 HeapWalkContext(bool valid) { _valid = valid; }
1828 void invalidate() { _valid = false; }
1829 bool is_valid() const { return _valid; }
1830 };
1831
1832 // A basic heap walk context for the deprecated heap walking functions.
1833 // The context for a basic heap walk are the callbacks and fields used by
1834 // the referrer caching scheme.
1835 class BasicHeapWalkContext: public HeapWalkContext {
1836 private:
1837 jvmtiHeapRootCallback _heap_root_callback;
1838 jvmtiStackReferenceCallback _stack_ref_callback;
1839 jvmtiObjectReferenceCallback _object_ref_callback;
1840
1841 // used for caching
1842 oop _last_referrer;
1843 jlong _last_referrer_tag;
1844
1845 public:
1846 BasicHeapWalkContext() : HeapWalkContext(false) { }
1847
1848 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1849 jvmtiStackReferenceCallback stack_ref_callback,
1850 jvmtiObjectReferenceCallback object_ref_callback) :
1851 HeapWalkContext(true),
1852 _heap_root_callback(heap_root_callback),
1853 _stack_ref_callback(stack_ref_callback),
1854 _object_ref_callback(object_ref_callback),
1855 _last_referrer(NULL),
1856 _last_referrer_tag(0) {
1857 }
1858
1859 // accessors
1860 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1861 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1862 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1863
1864 oop last_referrer() const { return _last_referrer; }
1865 void set_last_referrer(oop referrer) { _last_referrer = referrer; }
1866 jlong last_referrer_tag() const { return _last_referrer_tag; }
1867 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1868 };
1869
1870 // The advanced heap walk context for the FollowReferences functions.
1871 // The context is the callbacks, and the fields used for filtering.
1872 class AdvancedHeapWalkContext: public HeapWalkContext {
1873 private:
1874 jint _heap_filter;
1875 KlassHandle _klass_filter;
1876 const jvmtiHeapCallbacks* _heap_callbacks;
1877
1878 public:
1879 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1880
1881 AdvancedHeapWalkContext(jint heap_filter,
1882 KlassHandle klass_filter,
1883 const jvmtiHeapCallbacks* heap_callbacks) :
1884 HeapWalkContext(true),
1885 _heap_filter(heap_filter),
1886 _klass_filter(klass_filter),
1887 _heap_callbacks(heap_callbacks) {
1888 }
1889
1890 // accessors
1891 jint heap_filter() const { return _heap_filter; }
1892 KlassHandle klass_filter() const { return _klass_filter; }
1893
1894 const jvmtiHeapReferenceCallback heap_reference_callback() const {
1895 return _heap_callbacks->heap_reference_callback;
1896 };
1897 const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1898 return _heap_callbacks->primitive_field_callback;
1899 }
1900 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1901 return _heap_callbacks->array_primitive_value_callback;
1902 }
1903 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1904 return _heap_callbacks->string_primitive_value_callback;
1905 }
1906 };
1907
1908 // The CallbackInvoker is a class with static functions that the heap walk can call
1909 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1910 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1911 // mode is for the newer FollowReferences function which supports a lot of
1912 // additional callbacks.
1913 class CallbackInvoker : AllStatic {
1914 private:
1915 // heap walk styles
1916 enum { basic, advanced };
1917 static int _heap_walk_type;
1918 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1919 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1920
1921 // context for basic style heap walk
1922 static BasicHeapWalkContext _basic_context;
1923 static BasicHeapWalkContext* basic_context() {
1924 assert(_basic_context.is_valid(), "invalid");
1925 return &_basic_context;
1926 }
1927
1928 // context for advanced style heap walk
1929 static AdvancedHeapWalkContext _advanced_context;
1930 static AdvancedHeapWalkContext* advanced_context() {
1931 assert(_advanced_context.is_valid(), "invalid");
1932 return &_advanced_context;
1933 }
1934
1935 // context needed for all heap walks
1936 static JvmtiTagMap* _tag_map;
1937 static const void* _user_data;
1938 static GrowableArray<oop>* _visit_stack;
1939
1940 // accessors
1941 static JvmtiTagMap* tag_map() { return _tag_map; }
1942 static const void* user_data() { return _user_data; }
1943 static GrowableArray<oop>* visit_stack() { return _visit_stack; }
1944
1945 // if the object hasn't been visited then push it onto the visit stack
1946 // so that it will be visited later
1947 static inline bool check_for_visit(oop obj) {
1948 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1949 return true;
1950 }
1951
1952 // invoke basic style callbacks
1953 static inline bool invoke_basic_heap_root_callback
1954 (jvmtiHeapRootKind root_kind, oop obj);
1955 static inline bool invoke_basic_stack_ref_callback
1956 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1957 int slot, oop obj);
1958 static inline bool invoke_basic_object_reference_callback
1959 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1960
1961 // invoke advanced style callbacks
1962 static inline bool invoke_advanced_heap_root_callback
1963 (jvmtiHeapReferenceKind ref_kind, oop obj);
1964 static inline bool invoke_advanced_stack_ref_callback
1965 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1966 jmethodID method, jlocation bci, jint slot, oop obj);
1967 static inline bool invoke_advanced_object_reference_callback
1968 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1969
1970 // used to report the value of primitive fields
1971 static inline bool report_primitive_field
1972 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1973
1974 public:
1975 // initialize for basic mode
1976 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1977 GrowableArray<oop>* visit_stack,
1978 const void* user_data,
1979 BasicHeapWalkContext context);
1980
1981 // initialize for advanced mode
1982 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1983 GrowableArray<oop>* visit_stack,
1984 const void* user_data,
1985 AdvancedHeapWalkContext context);
1986
1987 // functions to report roots
1988 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
1989 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1990 jmethodID m, oop o);
1991 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1992 jmethodID method, jlocation bci, jint slot, oop o);
1993
1994 // functions to report references
1995 static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
1996 static inline bool report_class_reference(oop referrer, oop referree);
1997 static inline bool report_class_loader_reference(oop referrer, oop referree);
1998 static inline bool report_signers_reference(oop referrer, oop referree);
1999 static inline bool report_protection_domain_reference(oop referrer, oop referree);
2000 static inline bool report_superclass_reference(oop referrer, oop referree);
2001 static inline bool report_interface_reference(oop referrer, oop referree);
2002 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
2003 static inline bool report_field_reference(oop referrer, oop referree, jint slot);
2004 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
2005 static inline bool report_primitive_array_values(oop array);
2006 static inline bool report_string_value(oop str);
2007 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
2008 static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
2009 };
2010
2011 // statics
2012 int CallbackInvoker::_heap_walk_type;
2013 BasicHeapWalkContext CallbackInvoker::_basic_context;
2014 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
2015 JvmtiTagMap* CallbackInvoker::_tag_map;
2016 const void* CallbackInvoker::_user_data;
2017 GrowableArray<oop>* CallbackInvoker::_visit_stack;
2018
2019 // initialize for basic heap walk (IterateOverReachableObjects et al)
2020 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
2021 GrowableArray<oop>* visit_stack,
2022 const void* user_data,
2023 BasicHeapWalkContext context) {
2024 _tag_map = tag_map;
2025 _visit_stack = visit_stack;
2026 _user_data = user_data;
2027 _basic_context = context;
2028 _advanced_context.invalidate(); // will trigger assertion if used
2029 _heap_walk_type = basic;
2030 }
2031
2032 // initialize for advanced heap walk (FollowReferences)
2033 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
2034 GrowableArray<oop>* visit_stack,
2035 const void* user_data,
2036 AdvancedHeapWalkContext context) {
2037 _tag_map = tag_map;
2038 _visit_stack = visit_stack;
2039 _user_data = user_data;
2040 _advanced_context = context;
2041 _basic_context.invalidate(); // will trigger assertion if used
2042 _heap_walk_type = advanced;
2043 }
2044
2045
2046 // invoke basic style heap root callback
2047 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
2048 assert(ServiceUtil::visible_oop(obj), "checking");
2049
2050 // if we heap roots should be reported
2051 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
2052 if (cb == NULL) {
2053 return check_for_visit(obj);
2054 }
2055
2056 CallbackWrapper wrapper(tag_map(), obj);
2057 jvmtiIterationControl control = (*cb)(root_kind,
2058 wrapper.klass_tag(),
2059 wrapper.obj_size(),
2060 wrapper.obj_tag_p(),
2061 (void*)user_data());
2062 // push root to visit stack when following references
2063 if (control == JVMTI_ITERATION_CONTINUE &&
2064 basic_context()->object_ref_callback() != NULL) {
2065 visit_stack()->push(obj);
2066 }
2067 return control != JVMTI_ITERATION_ABORT;
2068 }
2069
2070 // invoke basic style stack ref callback
2071 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
2072 jlong thread_tag,
2073 jint depth,
2074 jmethodID method,
2075 jint slot,
2076 oop obj) {
2077 assert(ServiceUtil::visible_oop(obj), "checking");
2078
2079 // if we stack refs should be reported
2080 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
2081 if (cb == NULL) {
2082 return check_for_visit(obj);
2083 }
2084
2085 CallbackWrapper wrapper(tag_map(), obj);
2086 jvmtiIterationControl control = (*cb)(root_kind,
2087 wrapper.klass_tag(),
2088 wrapper.obj_size(),
2089 wrapper.obj_tag_p(),
2090 thread_tag,
2091 depth,
2092 method,
2093 slot,
2094 (void*)user_data());
2095 // push root to visit stack when following references
2096 if (control == JVMTI_ITERATION_CONTINUE &&
2097 basic_context()->object_ref_callback() != NULL) {
2098 visit_stack()->push(obj);
2099 }
2100 return control != JVMTI_ITERATION_ABORT;
2101 }
2102
2103 // invoke basic style object reference callback
2104 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2105 oop referrer,
2106 oop referree,
2107 jint index) {
2108
2109 assert(ServiceUtil::visible_oop(referrer), "checking");
2110 assert(ServiceUtil::visible_oop(referree), "checking");
2111
2112 BasicHeapWalkContext* context = basic_context();
2113
2114 // callback requires the referrer's tag. If it's the same referrer
2115 // as the last call then we use the cached value.
2116 jlong referrer_tag;
2117 if (referrer == context->last_referrer()) {
2118 referrer_tag = context->last_referrer_tag();
2119 } else {
2120 referrer_tag = tag_for(tag_map(), klassOop_if_java_lang_Class(referrer));
2121 }
2122
2123 // do the callback
2124 CallbackWrapper wrapper(tag_map(), referree);
2125 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2126 jvmtiIterationControl control = (*cb)(ref_kind,
2127 wrapper.klass_tag(),
2128 wrapper.obj_size(),
2129 wrapper.obj_tag_p(),
2130 referrer_tag,
2131 index,
2132 (void*)user_data());
2133
2134 // record referrer and referrer tag. For self-references record the
2135 // tag value from the callback as this might differ from referrer_tag.
2136 context->set_last_referrer(referrer);
2137 if (referrer == referree) {
2138 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2139 } else {
2140 context->set_last_referrer_tag(referrer_tag);
2141 }
2142
2143 if (control == JVMTI_ITERATION_CONTINUE) {
2144 return check_for_visit(referree);
2145 } else {
2146 return control != JVMTI_ITERATION_ABORT;
2147 }
2148 }
2149
2150 // invoke advanced style heap root callback
2151 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2152 oop obj) {
2153 assert(ServiceUtil::visible_oop(obj), "checking");
2154
2155 AdvancedHeapWalkContext* context = advanced_context();
2156
2157 // check that callback is provided
2158 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2159 if (cb == NULL) {
2160 return check_for_visit(obj);
2161 }
2162
2163 // apply class filter
2164 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2165 return check_for_visit(obj);
2166 }
2167
2168 // setup the callback wrapper
2169 CallbackWrapper wrapper(tag_map(), obj);
2170
2171 // apply tag filter
2172 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2173 wrapper.klass_tag(),
2174 context->heap_filter())) {
2175 return check_for_visit(obj);
2176 }
2177
2178 // for arrays we need the length, otherwise -1
2179 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2180
2181 // invoke the callback
2182 jint res = (*cb)(ref_kind,
2183 NULL, // referrer info
2184 wrapper.klass_tag(),
2185 0, // referrer_class_tag is 0 for heap root
2186 wrapper.obj_size(),
2187 wrapper.obj_tag_p(),
2188 NULL, // referrer_tag_p
2189 len,
2190 (void*)user_data());
2191 if (res & JVMTI_VISIT_ABORT) {
2192 return false;// referrer class tag
2193 }
2194 if (res & JVMTI_VISIT_OBJECTS) {
2195 check_for_visit(obj);
2196 }
2197 return true;
2198 }
2199
2200 // report a reference from a thread stack to an object
2201 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2202 jlong thread_tag,
2203 jlong tid,
2204 int depth,
2205 jmethodID method,
2206 jlocation bci,
2207 jint slot,
2208 oop obj) {
2209 assert(ServiceUtil::visible_oop(obj), "checking");
2210
2211 AdvancedHeapWalkContext* context = advanced_context();
2212
2213 // check that callback is provider
2214 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2215 if (cb == NULL) {
2216 return check_for_visit(obj);
2217 }
2218
2219 // apply class filter
2220 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2221 return check_for_visit(obj);
2222 }
2223
2224 // setup the callback wrapper
2225 CallbackWrapper wrapper(tag_map(), obj);
2226
2227 // apply tag filter
2228 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2229 wrapper.klass_tag(),
2230 context->heap_filter())) {
2231 return check_for_visit(obj);
2232 }
2233
2234 // setup the referrer info
2235 jvmtiHeapReferenceInfo reference_info;
2236 reference_info.stack_local.thread_tag = thread_tag;
2237 reference_info.stack_local.thread_id = tid;
2238 reference_info.stack_local.depth = depth;
2239 reference_info.stack_local.method = method;
2240 reference_info.stack_local.location = bci;
2241 reference_info.stack_local.slot = slot;
2242
2243 // for arrays we need the length, otherwise -1
2244 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2245
2246 // call into the agent
2247 int res = (*cb)(ref_kind,
2248 &reference_info,
2249 wrapper.klass_tag(),
2250 0, // referrer_class_tag is 0 for heap root (stack)
2251 wrapper.obj_size(),
2252 wrapper.obj_tag_p(),
2253 NULL, // referrer_tag is 0 for root
2254 len,
2255 (void*)user_data());
2256
2257 if (res & JVMTI_VISIT_ABORT) {
2258 return false;
2259 }
2260 if (res & JVMTI_VISIT_OBJECTS) {
2261 check_for_visit(obj);
2262 }
2263 return true;
2264 }
2265
2266 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2267 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2268 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2269 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2270 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2271 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2272 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2273 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2274
2275 // invoke the object reference callback to report a reference
2276 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2277 oop referrer,
2278 oop obj,
2279 jint index)
2280 {
2281 // field index is only valid field in reference_info
2282 static jvmtiHeapReferenceInfo reference_info = { 0 };
2283
2284 assert(ServiceUtil::visible_oop(referrer), "checking");
2285 assert(ServiceUtil::visible_oop(obj), "checking");
2286
2287 AdvancedHeapWalkContext* context = advanced_context();
2288
2289 // check that callback is provider
2290 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2291 if (cb == NULL) {
2292 return check_for_visit(obj);
2293 }
2294
2295 // apply class filter
2296 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2297 return check_for_visit(obj);
2298 }
2299
2300 // setup the callback wrapper
2301 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2302
2303 // apply tag filter
2304 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2305 wrapper.klass_tag(),
2306 context->heap_filter())) {
2307 return check_for_visit(obj);
2308 }
2309
2310 // field index is only valid field in reference_info
2311 reference_info.field.index = index;
2312
2313 // for arrays we need the length, otherwise -1
2314 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2315
2316 // invoke the callback
2317 int res = (*cb)(ref_kind,
2318 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2319 wrapper.klass_tag(),
2320 wrapper.referrer_klass_tag(),
2321 wrapper.obj_size(),
2322 wrapper.obj_tag_p(),
2323 wrapper.referrer_tag_p(),
2324 len,
2325 (void*)user_data());
2326
2327 if (res & JVMTI_VISIT_ABORT) {
2328 return false;
2329 }
2330 if (res & JVMTI_VISIT_OBJECTS) {
2331 check_for_visit(obj);
2332 }
2333 return true;
2334 }
2335
2336 // report a "simple root"
2337 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2338 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2339 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2340 assert(ServiceUtil::visible_oop(obj), "checking");
2341
2342 if (is_basic_heap_walk()) {
2343 // map to old style root kind
2344 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2345 return invoke_basic_heap_root_callback(root_kind, obj);
2346 } else {
2347 assert(is_advanced_heap_walk(), "wrong heap walk type");
2348 return invoke_advanced_heap_root_callback(kind, obj);
2349 }
2350 }
2351
2352
2353 // invoke the primitive array values
2354 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2355 assert(obj->is_typeArray(), "not a primitive array");
2356
2357 AdvancedHeapWalkContext* context = advanced_context();
2358 assert(context->array_primitive_value_callback() != NULL, "no callback");
2359
2360 // apply class filter
2361 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2362 return true;
2363 }
2364
2365 CallbackWrapper wrapper(tag_map(), obj);
2366
2367 // apply tag filter
2368 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2369 wrapper.klass_tag(),
2370 context->heap_filter())) {
2371 return true;
2372 }
2373
2374 // invoke the callback
2375 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2376 &wrapper,
2377 obj,
2378 (void*)user_data());
2379 return (!(res & JVMTI_VISIT_ABORT));
2380 }
2381
2382 // invoke the string value callback
2383 inline bool CallbackInvoker::report_string_value(oop str) {
2384 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2385
2386 AdvancedHeapWalkContext* context = advanced_context();
2387 assert(context->string_primitive_value_callback() != NULL, "no callback");
2388
2389 // apply class filter
2390 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2391 return true;
2392 }
2393
2394 CallbackWrapper wrapper(tag_map(), str);
2395
2396 // apply tag filter
2397 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2398 wrapper.klass_tag(),
2399 context->heap_filter())) {
2400 return true;
2401 }
2402
2403 // invoke the callback
2404 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2405 &wrapper,
2406 str,
2407 (void*)user_data());
2408 return (!(res & JVMTI_VISIT_ABORT));
2409 }
2410
2411 // invoke the primitive field callback
2412 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2413 oop obj,
2414 jint index,
2415 address addr,
2416 char type)
2417 {
2418 // for primitive fields only the index will be set
2419 static jvmtiHeapReferenceInfo reference_info = { 0 };
2420
2421 AdvancedHeapWalkContext* context = advanced_context();
2422 assert(context->primitive_field_callback() != NULL, "no callback");
2423
2424 // apply class filter
2425 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2426 return true;
2427 }
2428
2429 CallbackWrapper wrapper(tag_map(), obj);
2430
2431 // apply tag filter
2432 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2433 wrapper.klass_tag(),
2434 context->heap_filter())) {
2435 return true;
2436 }
2437
2438 // the field index in the referrer
2439 reference_info.field.index = index;
2440
2441 // map the type
2442 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2443
2444 // setup the jvalue
2445 jvalue value;
2446 copy_to_jvalue(&value, addr, value_type);
2447
2448 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2449 int res = (*cb)(ref_kind,
2450 &reference_info,
2451 wrapper.klass_tag(),
2452 wrapper.obj_tag_p(),
2453 value,
2454 value_type,
2455 (void*)user_data());
2456 return (!(res & JVMTI_VISIT_ABORT));
2457 }
2458
2459
2460 // instance field
2461 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2462 jint index,
2463 address value,
2464 char type) {
2465 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2466 obj,
2467 index,
2468 value,
2469 type);
2470 }
2471
2472 // static field
2473 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2474 jint index,
2475 address value,
2476 char type) {
2477 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2478 obj,
2479 index,
2480 value,
2481 type);
2482 }
2483
2484 // report a JNI local (root object) to the profiler
2485 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2486 if (is_basic_heap_walk()) {
2487 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2488 thread_tag,
2489 depth,
2490 m,
2491 -1,
2492 obj);
2493 } else {
2494 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2495 thread_tag, tid,
2496 depth,
2497 m,
2498 (jlocation)-1,
2499 -1,
2500 obj);
2501 }
2502 }
2503
2504
2505 // report a local (stack reference, root object)
2506 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2507 jlong tid,
2508 jint depth,
2509 jmethodID method,
2510 jlocation bci,
2511 jint slot,
2512 oop obj) {
2513 if (is_basic_heap_walk()) {
2514 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2515 thread_tag,
2516 depth,
2517 method,
2518 slot,
2519 obj);
2520 } else {
2521 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2522 thread_tag,
2523 tid,
2524 depth,
2525 method,
2526 bci,
2527 slot,
2528 obj);
2529 }
2530 }
2531
2532 // report an object referencing a class.
2533 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2534 if (is_basic_heap_walk()) {
2535 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2536 } else {
2537 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2538 }
2539 }
2540
2541 // report a class referencing its class loader.
2542 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2543 if (is_basic_heap_walk()) {
2544 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2545 } else {
2546 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2547 }
2548 }
2549
2550 // report a class referencing its signers.
2551 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2552 if (is_basic_heap_walk()) {
2553 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2554 } else {
2555 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2556 }
2557 }
2558
2559 // report a class referencing its protection domain..
2560 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2561 if (is_basic_heap_walk()) {
2562 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2563 } else {
2564 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2565 }
2566 }
2567
2568 // report a class referencing its superclass.
2569 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2570 if (is_basic_heap_walk()) {
2571 // Send this to be consistent with past implementation
2572 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2573 } else {
2574 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2575 }
2576 }
2577
2578 // report a class referencing one of its interfaces.
2579 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2580 if (is_basic_heap_walk()) {
2581 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2582 } else {
2583 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2584 }
2585 }
2586
2587 // report a class referencing one of its static fields.
2588 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2589 if (is_basic_heap_walk()) {
2590 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2591 } else {
2592 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2593 }
2594 }
2595
2596 // report an array referencing an element object
2597 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2598 if (is_basic_heap_walk()) {
2599 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2600 } else {
2601 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2602 }
2603 }
2604
2605 // report an object referencing an instance field object
2606 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2607 if (is_basic_heap_walk()) {
2608 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2609 } else {
2610 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2611 }
2612 }
2613
2614 // report an array referencing an element object
2615 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2616 if (is_basic_heap_walk()) {
2617 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2618 } else {
2619 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2620 }
2621 }
2622
2623 // A supporting closure used to process simple roots
2624 class SimpleRootsClosure : public OopClosure {
2625 private:
2626 jvmtiHeapReferenceKind _kind;
2627 bool _continue;
2628
2629 jvmtiHeapReferenceKind root_kind() { return _kind; }
2630
2631 public:
2632 void set_kind(jvmtiHeapReferenceKind kind) {
2633 _kind = kind;
2634 _continue = true;
2635 }
2636
2637 inline bool stopped() {
2638 return !_continue;
2639 }
2640
2641 void do_oop(oop* obj_p) {
2642 // iteration has terminated
2643 if (stopped()) {
2644 return;
2645 }
2646
2647 // ignore null or deleted handles
2648 oop o = *obj_p;
2649 if (o == NULL || o == JNIHandles::deleted_handle()) {
2650 return;
2651 }
2652
2653 jvmtiHeapReferenceKind kind = root_kind();
2654
2655 // many roots are Klasses so we use the java mirror
2656 if (o->is_klass()) {
2657 klassOop k = (klassOop)o;
2658 o = Klass::cast(k)->java_mirror();
2659 } else {
2660
2661 // SystemDictionary::always_strong_oops_do reports the application
2662 // class loader as a root. We want this root to be reported as
2663 // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2664 if (o->is_instance() && root_kind() == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2665 kind = JVMTI_HEAP_REFERENCE_OTHER;
2666 }
2667 }
2668
2669 // some objects are ignored - in the case of simple
2670 // roots it's mostly symbolOops that we are skipping
2671 // here.
2672 if (!ServiceUtil::visible_oop(o)) {
2673 return;
2674 }
2675
2676 // invoke the callback
2677 _continue = CallbackInvoker::report_simple_root(kind, o);
2678
2679 }
2680 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2681 };
2682
2683 // A supporting closure used to process JNI locals
2684 class JNILocalRootsClosure : public OopClosure {
2685 private:
2686 jlong _thread_tag;
2687 jlong _tid;
2688 jint _depth;
2689 jmethodID _method;
2690 bool _continue;
2691 public:
2692 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2693 _thread_tag = thread_tag;
2694 _tid = tid;
2695 _depth = depth;
2696 _method = method;
2697 _continue = true;
2698 }
2699
2700 inline bool stopped() {
2701 return !_continue;
2702 }
2703
2704 void do_oop(oop* obj_p) {
2705 // iteration has terminated
2706 if (stopped()) {
2707 return;
2708 }
2709
2710 // ignore null or deleted handles
2711 oop o = *obj_p;
2712 if (o == NULL || o == JNIHandles::deleted_handle()) {
2713 return;
2714 }
2715
2716 if (!ServiceUtil::visible_oop(o)) {
2717 return;
2718 }
2719
2720 // invoke the callback
2721 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2722 }
2723 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2724 };
2725
2726
2727 // A VM operation to iterate over objects that are reachable from
2728 // a set of roots or an initial object.
2729 //
2730 // For VM_HeapWalkOperation the set of roots used is :-
2731 //
2732 // - All JNI global references
2733 // - All inflated monitors
2734 // - All classes loaded by the boot class loader (or all classes
2735 // in the event that class unloading is disabled)
2736 // - All java threads
2737 // - For each java thread then all locals and JNI local references
2738 // on the thread's execution stack
2739 // - All visible/explainable objects from Universes::oops_do
2740 //
2741 class VM_HeapWalkOperation: public VM_Operation {
2742 private:
2743 enum {
2744 initial_visit_stack_size = 4000
2745 };
2746
2747 bool _is_advanced_heap_walk; // indicates FollowReferences
2748 JvmtiTagMap* _tag_map;
2749 Handle _initial_object;
2750 GrowableArray<oop>* _visit_stack; // the visit stack
2751
2752 bool _collecting_heap_roots; // are we collecting roots
2753 bool _following_object_refs; // are we following object references
2754
2755 bool _reporting_primitive_fields; // optional reporting
2756 bool _reporting_primitive_array_values;
2757 bool _reporting_string_values;
2758
2759 GrowableArray<oop>* create_visit_stack() {
2760 return new (ResourceObj::C_HEAP) GrowableArray<oop>(initial_visit_stack_size, true);
2761 }
2762
2763 // accessors
2764 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2765 JvmtiTagMap* tag_map() const { return _tag_map; }
2766 Handle initial_object() const { return _initial_object; }
2767
2768 bool is_following_references() const { return _following_object_refs; }
2769
2770 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2771 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2772 bool is_reporting_string_values() const { return _reporting_string_values; }
2773
2774 GrowableArray<oop>* visit_stack() const { return _visit_stack; }
2775
2776 // iterate over the various object types
2777 inline bool iterate_over_array(oop o);
2778 inline bool iterate_over_type_array(oop o);
2779 inline bool iterate_over_class(klassOop o);
2780 inline bool iterate_over_object(oop o);
2781
2782 // root collection
2783 inline bool collect_simple_roots();
2784 inline bool collect_stack_roots();
2785 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2786
2787 // visit an object
2788 inline bool visit(oop o);
2789
2790 public:
2791 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2792 Handle initial_object,
2793 BasicHeapWalkContext callbacks,
2794 const void* user_data);
2795
2796 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2797 Handle initial_object,
2798 AdvancedHeapWalkContext callbacks,
2799 const void* user_data);
2800
2801 ~VM_HeapWalkOperation();
2802
2803 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2804 void doit();
2805 };
2806
2807
2808 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2809 Handle initial_object,
2810 BasicHeapWalkContext callbacks,
2811 const void* user_data) {
2812 _is_advanced_heap_walk = false;
2813 _tag_map = tag_map;
2814 _initial_object = initial_object;
2815 _following_object_refs = (callbacks.object_ref_callback() != NULL);
2816 _reporting_primitive_fields = false;
2817 _reporting_primitive_array_values = false;
2818 _reporting_string_values = false;
2819 _visit_stack = create_visit_stack();
2820
2821
2822 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2823 }
2824
2825 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2826 Handle initial_object,
2827 AdvancedHeapWalkContext callbacks,
2828 const void* user_data) {
2829 _is_advanced_heap_walk = true;
2830 _tag_map = tag_map;
2831 _initial_object = initial_object;
2832 _following_object_refs = true;
2833 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2834 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2835 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2836 _visit_stack = create_visit_stack();
2837
2838 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2839 }
2840
2841 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2842 if (_following_object_refs) {
2843 assert(_visit_stack != NULL, "checking");
2844 delete _visit_stack;
2845 _visit_stack = NULL;
2846 }
2847 }
2848
2849 // an array references its class and has a reference to
2850 // each element in the array
2851 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2852 objArrayOop array = objArrayOop(o);
2853 if (array->klass() == Universe::systemObjArrayKlassObj()) {
2854 // filtered out
2855 return true;
2856 }
2857
2858 // array reference to its class
2859 oop mirror = objArrayKlass::cast(array->klass())->java_mirror();
2860 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2861 return false;
2862 }
2863
2864 // iterate over the array and report each reference to a
2865 // non-null element
2866 for (int index=0; index<array->length(); index++) {
2867 oop elem = array->obj_at(index);
2868 if (elem == NULL) {
2869 continue;
2870 }
2871
2872 // report the array reference o[index] = elem
2873 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2874 return false;
2875 }
2876 }
2877 return true;
2878 }
2879
2880 // a type array references its class
2881 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2882 klassOop k = o->klass();
2883 oop mirror = Klass::cast(k)->java_mirror();
2884 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2885 return false;
2886 }
2887
2888 // report the array contents if required
2889 if (is_reporting_primitive_array_values()) {
2890 if (!CallbackInvoker::report_primitive_array_values(o)) {
2891 return false;
2892 }
2893 }
2894 return true;
2895 }
2896
2897 // verify that a static oop field is in range
2898 static inline bool verify_static_oop(instanceKlass* ik,
2899 klassOop k, int offset) {
2900 address obj_p = (address)k + offset;
2901 address start = (address)ik->start_of_static_fields();
2902 address end = start + (ik->static_oop_field_size() * heapOopSize);
2903 assert(end >= start, "sanity check");
2904
2905 if (obj_p >= start && obj_p < end) {
2906 return true;
2907 } else {
2908 return false;
2909 }
2910 }
2911
2912 // a class references its super class, interfaces, class loader, ...
2913 // and finally its static fields
2914 inline bool VM_HeapWalkOperation::iterate_over_class(klassOop k) {
2915 int i;
2916 Klass* klass = klassOop(k)->klass_part();
2917
2918 if (klass->oop_is_instance()) {
2919 instanceKlass* ik = instanceKlass::cast(k);
2920
2921 // ignore the class if it's has been initialized yet
2922 if (!ik->is_linked()) {
2923 return true;
2924 }
2925
2926 // get the java mirror
2927 oop mirror = klass->java_mirror();
2928
2929 // super (only if something more interesting than java.lang.Object)
2930 klassOop java_super = ik->java_super();
2931 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2932 oop super = Klass::cast(java_super)->java_mirror();
2933 if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2934 return false;
2935 }
2936 }
2937
2938 // class loader
2939 oop cl = ik->class_loader();
2940 if (cl != NULL) {
2941 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2942 return false;
2943 }
2944 }
2945
2946 // protection domain
2947 oop pd = ik->protection_domain();
2948 if (pd != NULL) {
2949 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2950 return false;
2951 }
2952 }
2953
2954 // signers
2955 oop signers = ik->signers();
2956 if (signers != NULL) {
2957 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2958 return false;
2959 }
2960 }
2961
2962 // references from the constant pool
2963 {
2964 const constantPoolOop pool = ik->constants();
2965 for (int i = 1; i < pool->length(); i++) {
2966 constantTag tag = pool->tag_at(i).value();
2967 if (tag.is_string() || tag.is_klass()) {
2968 oop entry;
2969 if (tag.is_string()) {
2970 entry = pool->resolved_string_at(i);
2971 assert(java_lang_String::is_instance(entry), "must be string");
2972 } else {
2973 entry = Klass::cast(pool->resolved_klass_at(i))->java_mirror();
2974 }
2975 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2976 return false;
2977 }
2978 }
2979 }
2980 }
2981
2982 // interfaces
2983 // (These will already have been reported as references from the constant pool
2984 // but are specified by IterateOverReachableObjects and must be reported).
2985 objArrayOop interfaces = ik->local_interfaces();
2986 for (i = 0; i < interfaces->length(); i++) {
2987 oop interf = Klass::cast((klassOop)interfaces->obj_at(i))->java_mirror();
2988 if (interf == NULL) {
2989 continue;
2990 }
2991 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
2992 return false;
2993 }
2994 }
2995
2996 // iterate over the static fields
2997
2998 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
2999 for (i=0; i<field_map->field_count(); i++) {
3000 ClassFieldDescriptor* field = field_map->field_at(i);
3001 char type = field->field_type();
3002 if (!is_primitive_field_type(type)) {
3003 oop fld_o = k->obj_field(field->field_offset());
3004 assert(verify_static_oop(ik, k, field->field_offset()), "sanity check");
3005 if (fld_o != NULL) {
3006 int slot = field->field_index();
3007 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
3008 delete field_map;
3009 return false;
3010 }
3011 }
3012 } else {
3013 if (is_reporting_primitive_fields()) {
3014 address addr = (address)k + field->field_offset();
3015 int slot = field->field_index();
3016 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
3017 delete field_map;
3018 return false;
3019 }
3020 }
3021 }
3022 }
3023 delete field_map;
3024
3025 return true;
3026 }
3027
3028 return true;
3029 }
3030
3031 // an object references a class and its instance fields
3032 // (static fields are ignored here as we report these as
3033 // references from the class).
3034 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
3035 // reference to the class
3036 if (!CallbackInvoker::report_class_reference(o, Klass::cast(o->klass())->java_mirror())) {
3037 return false;
3038 }
3039
3040 // iterate over instance fields
3041 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
3042 for (int i=0; i<field_map->field_count(); i++) {
3043 ClassFieldDescriptor* field = field_map->field_at(i);
3044 char type = field->field_type();
3045 if (!is_primitive_field_type(type)) {
3046 oop fld_o = o->obj_field(field->field_offset());
3047 if (fld_o != NULL) {
3048 // reflection code may have a reference to a klassOop.
3049 // - see sun.reflect.UnsafeStaticFieldAccessorImpl and sun.misc.Unsafe
3050 if (fld_o->is_klass()) {
3051 klassOop k = (klassOop)fld_o;
3052 fld_o = Klass::cast(k)->java_mirror();
3053 }
3054 int slot = field->field_index();
3055 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
3056 return false;
3057 }
3058 }
3059 } else {
3060 if (is_reporting_primitive_fields()) {
3061 // primitive instance field
3062 address addr = (address)o + field->field_offset();
3063 int slot = field->field_index();
3064 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
3065 return false;
3066 }
3067 }
3068 }
3069 }
3070
3071 // if the object is a java.lang.String
3072 if (is_reporting_string_values() &&
3073 o->klass() == SystemDictionary::String_klass()) {
3074 if (!CallbackInvoker::report_string_value(o)) {
3075 return false;
3076 }
3077 }
3078 return true;
3079 }
3080
3081
3082 // collects all simple (non-stack) roots.
3083 // if there's a heap root callback provided then the callback is
3084 // invoked for each simple root.
3085 // if an object reference callback is provided then all simple
3086 // roots are pushed onto the marking stack so that they can be
3087 // processed later
3088 //
3089 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3090 SimpleRootsClosure blk;
3091
3092 // JNI globals
3093 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3094 JNIHandles::oops_do(&blk);
3095 if (blk.stopped()) {
3096 return false;
3097 }
3098
3099 // Preloaded classes and loader from the system dictionary
3100 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3101 SystemDictionary::always_strong_oops_do(&blk);
3102 if (blk.stopped()) {
3103 return false;
3104 }
3105
3106 // Inflated monitors
3107 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3108 ObjectSynchronizer::oops_do(&blk);
3109 if (blk.stopped()) {
3110 return false;
3111 }
3112
3113 // Threads
3114 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3115 oop threadObj = thread->threadObj();
3116 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3117 bool cont = CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, threadObj);
3118 if (!cont) {
3119 return false;
3120 }
3121 }
3122 }
3123
3124 // Other kinds of roots maintained by HotSpot
3125 // Many of these won't be visible but others (such as instances of important
3126 // exceptions) will be visible.
3127 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3128 Universe::oops_do(&blk);
3129
3130 // If there are any non-perm roots in the code cache, visit them.
3131 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3132 CodeBlobToOopClosure look_in_blobs(&blk, false);
3133 CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3134
3135 return true;
3136 }
3137
3138 // Walk the stack of a given thread and find all references (locals
3139 // and JNI calls) and report these as stack references
3140 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3141 JNILocalRootsClosure* blk)
3142 {
3143 oop threadObj = java_thread->threadObj();
3144 assert(threadObj != NULL, "sanity check");
3145
3146 // only need to get the thread's tag once per thread
3147 jlong thread_tag = tag_for(_tag_map, threadObj);
3148
3149 // also need the thread id
3150 jlong tid = java_lang_Thread::thread_id(threadObj);
3151
3152
3153 if (java_thread->has_last_Java_frame()) {
3154
3155 // vframes are resource allocated
3156 Thread* current_thread = Thread::current();
3157 ResourceMark rm(current_thread);
3158 HandleMark hm(current_thread);
3159
3160 RegisterMap reg_map(java_thread);
3161 frame f = java_thread->last_frame();
3162 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3163
3164 bool is_top_frame = true;
3165 int depth = 0;
3166 frame* last_entry_frame = NULL;
3167
3168 while (vf != NULL) {
3169 if (vf->is_java_frame()) {
3170
3171 // java frame (interpreted, compiled, ...)
3172 javaVFrame *jvf = javaVFrame::cast(vf);
3173
3174 // the jmethodID
3175 jmethodID method = jvf->method()->jmethod_id();
3176
3177 if (!(jvf->method()->is_native())) {
3178 jlocation bci = (jlocation)jvf->bci();
3179 StackValueCollection* locals = jvf->locals();
3180 for (int slot=0; slot<locals->size(); slot++) {
3181 if (locals->at(slot)->type() == T_OBJECT) {
3182 oop o = locals->obj_at(slot)();
3183 if (o == NULL) {
3184 continue;
3185 }
3186
3187 // stack reference
3188 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3189 bci, slot, o)) {
3190 return false;
3191 }
3192 }
3193 }
3194 } else {
3195 blk->set_context(thread_tag, tid, depth, method);
3196 if (is_top_frame) {
3197 // JNI locals for the top frame.
3198 java_thread->active_handles()->oops_do(blk);
3199 } else {
3200 if (last_entry_frame != NULL) {
3201 // JNI locals for the entry frame
3202 assert(last_entry_frame->is_entry_frame(), "checking");
3203 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3204 }
3205 }
3206 }
3207 last_entry_frame = NULL;
3208 depth++;
3209 } else {
3210 // externalVFrame - for an entry frame then we report the JNI locals
3211 // when we find the corresponding javaVFrame
3212 frame* fr = vf->frame_pointer();
3213 assert(fr != NULL, "sanity check");
3214 if (fr->is_entry_frame()) {
3215 last_entry_frame = fr;
3216 }
3217 }
3218
3219 vf = vf->sender();
3220 is_top_frame = false;
3221 }
3222 } else {
3223 // no last java frame but there may be JNI locals
3224 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3225 java_thread->active_handles()->oops_do(blk);
3226 }
3227 return true;
3228 }
3229
3230
3231 // collects all stack roots - for each thread it walks the execution
3232 // stack to find all references and local JNI refs.
3233 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3234 JNILocalRootsClosure blk;
3235 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3236 oop threadObj = thread->threadObj();
3237 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3238 if (!collect_stack_roots(thread, &blk)) {
3239 return false;
3240 }
3241 }
3242 }
3243 return true;
3244 }
3245
3246 // visit an object
3247 // first mark the object as visited
3248 // second get all the outbound references from this object (in other words, all
3249 // the objects referenced by this object).
3250 //
3251 bool VM_HeapWalkOperation::visit(oop o) {
3252 // mark object as visited
3253 assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3254 ObjectMarker::mark(o);
3255
3256 // instance
3257 if (o->is_instance()) {
3258 if (o->klass() == SystemDictionary::Class_klass()) {
3259 o = klassOop_if_java_lang_Class(o);
3260 if (o->is_klass()) {
3261 // a java.lang.Class
3262 return iterate_over_class(klassOop(o));
3263 }
3264 } else {
3265 return iterate_over_object(o);
3266 }
3267 }
3268
3269 // object array
3270 if (o->is_objArray()) {
3271 return iterate_over_array(o);
3272 }
3273
3274 // type array
3275 if (o->is_typeArray()) {
3276 return iterate_over_type_array(o);
3277 }
3278
3279 return true;
3280 }
3281
3282 void VM_HeapWalkOperation::doit() {
3283 ResourceMark rm;
3284 ObjectMarkerController marker;
3285 ClassFieldMapCacheMark cm;
3286
3287 assert(visit_stack()->is_empty(), "visit stack must be empty");
3288
3289 // the heap walk starts with an initial object or the heap roots
3290 if (initial_object().is_null()) {
3291 if (!collect_simple_roots()) return;
3292 if (!collect_stack_roots()) return;
3293 } else {
3294 visit_stack()->push(initial_object()());
3295 }
3296
3297 // object references required
3298 if (is_following_references()) {
3299
3300 // visit each object until all reachable objects have been
3301 // visited or the callback asked to terminate the iteration.
3302 while (!visit_stack()->is_empty()) {
3303 oop o = visit_stack()->pop();
3304 if (!ObjectMarker::visited(o)) {
3305 if (!visit(o)) {
3306 break;
3307 }
3308 }
3309 }
3310 }
3311 }
3312
3313 // iterate over all objects that are reachable from a set of roots
3314 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3315 jvmtiStackReferenceCallback stack_ref_callback,
3316 jvmtiObjectReferenceCallback object_ref_callback,
3317 const void* user_data) {
3318 MutexLocker ml(Heap_lock);
3319 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3320 VM_HeapWalkOperation op(this, Handle(), context, user_data);
3321 VMThread::execute(&op);
3322 }
3323
3324 // iterate over all objects that are reachable from a given object
3325 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3326 jvmtiObjectReferenceCallback object_ref_callback,
3327 const void* user_data) {
3328 oop obj = JNIHandles::resolve(object);
3329 Handle initial_object(Thread::current(), obj);
3330
3331 MutexLocker ml(Heap_lock);
3332 BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3333 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3334 VMThread::execute(&op);
3335 }
3336
3337 // follow references from an initial object or the GC roots
3338 void JvmtiTagMap::follow_references(jint heap_filter,
3339 KlassHandle klass,
3340 jobject object,
3341 const jvmtiHeapCallbacks* callbacks,
3342 const void* user_data)
3343 {
3344 oop obj = JNIHandles::resolve(object);
3345 Handle initial_object(Thread::current(), obj);
3346
3347 MutexLocker ml(Heap_lock);
3348 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3349 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3350 VMThread::execute(&op);
3351 }
3352
3353
3354 // called post-GC
3355 // - for each JVMTI environment with an object tag map, call its rehash
3356 // function to re-sync with the new object locations.
3357 void JvmtiTagMap::gc_epilogue(bool full) {
3358 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
3359 if (JvmtiEnv::environments_might_exist()) {
3360 // re-obtain the memory region for the young generation (might
3361 // changed due to adaptive resizing policy)
3362 get_young_generation();
3363
3364 JvmtiEnvIterator it;
3365 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3366 JvmtiTagMap* tag_map = env->tag_map();
3367 if (tag_map != NULL && !tag_map->is_empty()) {
3368 TraceTime t(full ? "JVMTI Full Rehash " : "JVMTI Rehash ", TraceJVMTIObjectTagging);
3369 if (full) {
3370 tag_map->rehash(0, n_hashmaps);
3371 } else {
3372 tag_map->rehash(0, 0); // tag map for young gen only
3373 }
3374 }
3375 }
3376 }
3377 }
3378
3379 // CMS has completed referencing processing so we may have JNI weak refs
3380 // to objects in the CMS generation that have been GC'ed.
3381 void JvmtiTagMap::cms_ref_processing_epilogue() {
3382 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
3383 assert(UseConcMarkSweepGC, "should only be used with CMS");
3384 if (JvmtiEnv::environments_might_exist()) {
3385 JvmtiEnvIterator it;
3386 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3387 JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map();
3388 if (tag_map != NULL && !tag_map->is_empty()) {
3389 TraceTime t("JVMTI Rehash (CMS) ", TraceJVMTIObjectTagging);
3390 tag_map->rehash(1, n_hashmaps); // assume CMS not used in young gen
3391 }
3392 }
3393 }
3394 }
3395
3396
3397 // For each entry in the hashmaps 'start' to 'end' :
3398 //
3399 // 1. resolve the JNI weak reference
3400 //
3401 // 2. If it resolves to NULL it means the object has been freed so the entry
3402 // is removed, the weak reference destroyed, and the object free event is
3403 // posted (if enabled).
3404 //
3405 // 3. If the weak reference resolves to an object then we re-hash the object
3406 // to see if it has moved or has been promoted (from the young to the old
3407 // generation for example).
3408 //
3409 void JvmtiTagMap::rehash(int start, int end) {
3410
3411 // does this environment have the OBJECT_FREE event enabled
3412 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3413
3414 // counters used for trace message
3415 int freed = 0;
3416 int moved = 0;
3417 int promoted = 0;
3418
3419 // we assume there are two hashmaps - one for the young generation
3420 // and the other for all other spaces.
3421 assert(n_hashmaps == 2, "not implemented");
3422 JvmtiTagHashmap* young_hashmap = _hashmap[0];
3423 JvmtiTagHashmap* other_hashmap = _hashmap[1];
3424
3425 // reenable sizing (if disabled)
3426 young_hashmap->set_resizing_enabled(true);
3427 other_hashmap->set_resizing_enabled(true);
3428
3429 // when re-hashing the hashmap corresponding to the young generation we
3430 // collect the entries corresponding to objects that have been promoted.
3431 JvmtiTagHashmapEntry* promoted_entries = NULL;
3432
3433 if (end >= n_hashmaps) {
3434 end = n_hashmaps - 1;
3435 }
3436
3437 for (int i=start; i <= end; i++) {
3438 JvmtiTagHashmap* hashmap = _hashmap[i];
3439
3440 // if the hashmap is empty then we can skip it
3441 if (hashmap->_entry_count == 0) {
3442 continue;
3443 }
3444
3445 // now iterate through each entry in the table
3446
3447 JvmtiTagHashmapEntry** table = hashmap->table();
3448 int size = hashmap->size();
3449
3450 for (int pos=0; pos<size; pos++) {
3451 JvmtiTagHashmapEntry* entry = table[pos];
3452 JvmtiTagHashmapEntry* prev = NULL;
3453
3454 while (entry != NULL) {
3455 JvmtiTagHashmapEntry* next = entry->next();
3456
3457 jweak ref = entry->object();
3458 oop oop = JNIHandles::resolve(ref);
3459
3460 // has object been GC'ed
3461 if (oop == NULL) {
3462 // grab the tag
3463 jlong tag = entry->tag();
3464 guarantee(tag != 0, "checking");
3465
3466 // remove GC'ed entry from hashmap and return the
3467 // entry to the free list
3468 hashmap->remove(prev, pos, entry);
3469 destroy_entry(entry);
3470
3471 // destroy the weak ref
3472 JNIHandles::destroy_weak_global(ref);
3473
3474 // post the event to the profiler
3475 if (post_object_free) {
3476 JvmtiExport::post_object_free(env(), tag);
3477 }
3478
3479 freed++;
3480 entry = next;
3481 continue;
3482 }
3483
3484 // if this is the young hashmap then the object is either promoted
3485 // or moved.
3486 // if this is the other hashmap then the object is moved.
3487
3488 bool same_gen;
3489 if (i == 0) {
3490 assert(hashmap == young_hashmap, "checking");
3491 same_gen = is_in_young(oop);
3492 } else {
3493 same_gen = true;
3494 }
3495
3496
3497 if (same_gen) {
3498 // if the object has moved then re-hash it and move its
3499 // entry to its new location.
3500 unsigned int new_pos = JvmtiTagHashmap::hash(oop, size);
3501 if (new_pos != (unsigned int)pos) {
3502 if (prev == NULL) {
3503 table[pos] = next;
3504 } else {
3505 prev->set_next(next);
3506 }
3507 entry->set_next(table[new_pos]);
3508 table[new_pos] = entry;
3509 moved++;
3510 } else {
3511 // object didn't move
3512 prev = entry;
3513 }
3514 } else {
3515 // object has been promoted so remove the entry from the
3516 // young hashmap
3517 assert(hashmap == young_hashmap, "checking");
3518 hashmap->remove(prev, pos, entry);
3519
3520 // move the entry to the promoted list
3521 entry->set_next(promoted_entries);
3522 promoted_entries = entry;
3523 }
3524
3525 entry = next;
3526 }
3527 }
3528 }
3529
3530
3531 // add the entries, corresponding to the promoted objects, to the
3532 // other hashmap.
3533 JvmtiTagHashmapEntry* entry = promoted_entries;
3534 while (entry != NULL) {
3535 oop o = JNIHandles::resolve(entry->object());
3536 assert(hashmap_for(o) == other_hashmap, "checking");
3537 JvmtiTagHashmapEntry* next = entry->next();
3538 other_hashmap->add(o, entry);
3539 entry = next;
3540 promoted++;
3541 }
3542
3543 // stats
3544 if (TraceJVMTIObjectTagging) {
3545 int total_moves = promoted + moved;
3546
3547 int post_total = 0;
3548 for (int i=0; i<n_hashmaps; i++) {
3549 post_total += _hashmap[i]->_entry_count;
3550 }
3551 int pre_total = post_total + freed;
3552
3553 tty->print("(%d->%d, %d freed, %d promoted, %d total moves)",
3554 pre_total, post_total, freed, promoted, total_moves);
3555 }
3556 }