1 /*
2 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "jvmtifiles/jvmtiEnv.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "oops/oop.inline2.hpp"
32 #include "prims/jvmtiEventController.hpp"
33 #include "prims/jvmtiEventController.inline.hpp"
34 #include "prims/jvmtiExport.hpp"
35 #include "prims/jvmtiImpl.hpp"
36 #include "prims/jvmtiTagMap.hpp"
37 #include "runtime/biasedLocking.hpp"
38 #include "runtime/javaCalls.hpp"
39 #include "runtime/jniHandles.hpp"
40 #include "runtime/mutex.hpp"
41 #include "runtime/mutexLocker.hpp"
42 #include "runtime/reflectionUtils.hpp"
43 #include "runtime/vframe.hpp"
44 #include "runtime/vmThread.hpp"
45 #include "runtime/vm_operations.hpp"
46 #include "services/serviceUtil.hpp"
47 #ifndef SERIALGC
48 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
49 #endif
50
51 // JvmtiTagHashmapEntry
52 //
53 // Each entry encapsulates a JNI weak reference to the tagged object
54 // and the tag value. In addition an entry includes a next pointer which
55 // is used to chain entries together.
56
57 class JvmtiTagHashmapEntry : public CHeapObj {
58 private:
59 friend class JvmtiTagMap;
60
61 jweak _object; // JNI weak ref to tagged object
62 jlong _tag; // the tag
63 JvmtiTagHashmapEntry* _next; // next on the list
64
65 inline void init(jweak object, jlong tag) {
66 _object = object;
67 _tag = tag;
68 _next = NULL;
69 }
70
71 // constructor
72 JvmtiTagHashmapEntry(jweak object, jlong tag) { init(object, tag); }
73
74 public:
75
76 // accessor methods
77 inline jweak object() const { return _object; }
78 inline jlong tag() const { return _tag; }
79
80 inline void set_tag(jlong tag) {
81 assert(tag != 0, "can't be zero");
82 _tag = tag;
83 }
84
85 inline JvmtiTagHashmapEntry* next() const { return _next; }
86 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; }
87 };
88
89
90 // JvmtiTagHashmap
91 //
92 // A hashmap is essentially a table of pointers to entries. Entries
93 // are hashed to a location, or position in the table, and then
94 // chained from that location. The "key" for hashing is address of
95 // the object, or oop. The "value" is the JNI weak reference to the
96 // object and the tag value. Keys are not stored with the entry.
97 // Instead the weak reference is resolved to obtain the key.
98 //
99 // A hashmap maintains a count of the number entries in the hashmap
100 // and resizes if the number of entries exceeds a given threshold.
101 // The threshold is specified as a percentage of the size - for
102 // example a threshold of 0.75 will trigger the hashmap to resize
103 // if the number of entries is >75% of table size.
104 //
105 // A hashmap provides functions for adding, removing, and finding
106 // entries. It also provides a function to iterate over all entries
107 // in the hashmap.
108
109 class JvmtiTagHashmap : public CHeapObj {
110 private:
111 friend class JvmtiTagMap;
112
113 enum {
114 small_trace_threshold = 10000, // threshold for tracing
115 medium_trace_threshold = 100000,
116 large_trace_threshold = 1000000,
117 initial_trace_threshold = small_trace_threshold
118 };
119
120 static int _sizes[]; // array of possible hashmap sizes
121 int _size; // actual size of the table
122 int _size_index; // index into size table
123
124 int _entry_count; // number of entries in the hashmap
125
126 float _load_factor; // load factor as a % of the size
127 int _resize_threshold; // computed threshold to trigger resizing.
128 bool _resizing_enabled; // indicates if hashmap can resize
129
130 int _trace_threshold; // threshold for trace messages
131
132 JvmtiTagHashmapEntry** _table; // the table of entries.
133
134 // private accessors
135 int resize_threshold() const { return _resize_threshold; }
136 int trace_threshold() const { return _trace_threshold; }
137
138 // initialize the hashmap
139 void init(int size_index=0, float load_factor=4.0f) {
140 int initial_size = _sizes[size_index];
141 _size_index = size_index;
142 _size = initial_size;
143 _entry_count = 0;
144 if (TraceJVMTIObjectTagging) {
145 _trace_threshold = initial_trace_threshold;
146 } else {
147 _trace_threshold = -1;
148 }
149 _load_factor = load_factor;
150 _resize_threshold = (int)(_load_factor * _size);
151 _resizing_enabled = true;
152 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
153 _table = (JvmtiTagHashmapEntry**)os::malloc(s);
154 if (_table == NULL) {
155 vm_exit_out_of_memory(s, "unable to allocate initial hashtable for jvmti object tags");
156 }
157 for (int i=0; i<initial_size; i++) {
158 _table[i] = NULL;
159 }
160 }
161
162 // hash a given key (oop) with the specified size
163 static unsigned int hash(oop key, int size) {
164 // shift right to get better distribution (as these bits will be zero
165 // with aligned addresses)
166 unsigned int addr = (unsigned int)((intptr_t)key);
167 #ifdef _LP64
168 return (addr >> 3) % size;
169 #else
170 return (addr >> 2) % size;
171 #endif
172 }
173
174 // hash a given key (oop)
175 unsigned int hash(oop key) {
176 return hash(key, _size);
177 }
178
179 // resize the hashmap - allocates a large table and re-hashes
180 // all entries into the new table.
181 void resize() {
182 int new_size_index = _size_index+1;
183 int new_size = _sizes[new_size_index];
184 if (new_size < 0) {
185 // hashmap already at maximum capacity
186 return;
187 }
188
189 // allocate new table
190 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
191 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s);
192 if (new_table == NULL) {
193 warning("unable to allocate larger hashtable for jvmti object tags");
194 set_resizing_enabled(false);
195 return;
196 }
197
198 // initialize new table
199 int i;
200 for (i=0; i<new_size; i++) {
201 new_table[i] = NULL;
202 }
203
204 // rehash all entries into the new table
205 for (i=0; i<_size; i++) {
206 JvmtiTagHashmapEntry* entry = _table[i];
207 while (entry != NULL) {
208 JvmtiTagHashmapEntry* next = entry->next();
209 oop key = JNIHandles::resolve(entry->object());
210 assert(key != NULL, "jni weak reference cleared!!");
211 unsigned int h = hash(key, new_size);
212 JvmtiTagHashmapEntry* anchor = new_table[h];
213 if (anchor == NULL) {
214 new_table[h] = entry;
215 entry->set_next(NULL);
216 } else {
217 entry->set_next(anchor);
218 new_table[h] = entry;
219 }
220 entry = next;
221 }
222 }
223
224 // free old table and update settings.
225 os::free((void*)_table);
226 _table = new_table;
227 _size_index = new_size_index;
228 _size = new_size;
229
230 // compute new resize threshold
231 _resize_threshold = (int)(_load_factor * _size);
232 }
233
234
235 // internal remove function - remove an entry at a given position in the
236 // table.
237 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
238 assert(pos >= 0 && pos < _size, "out of range");
239 if (prev == NULL) {
240 _table[pos] = entry->next();
241 } else {
242 prev->set_next(entry->next());
243 }
244 assert(_entry_count > 0, "checking");
245 _entry_count--;
246 }
247
248 // resizing switch
249 bool is_resizing_enabled() const { return _resizing_enabled; }
250 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; }
251
252 // debugging
253 void print_memory_usage();
254 void compute_next_trace_threshold();
255
256 public:
257
258 // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
259 // The preferred size is rounded down to an actual size.
260 JvmtiTagHashmap(int size, float load_factor=0.0f) {
261 int i=0;
262 while (_sizes[i] < size) {
263 if (_sizes[i] < 0) {
264 assert(i > 0, "sanity check");
265 i--;
266 break;
267 }
268 i++;
269 }
270
271 // if a load factor is specified then use it, otherwise use default
272 if (load_factor > 0.01f) {
273 init(i, load_factor);
274 } else {
275 init(i);
276 }
277 }
278
279 // create a JvmtiTagHashmap with default settings
280 JvmtiTagHashmap() {
281 init();
282 }
283
284 // release table when JvmtiTagHashmap destroyed
285 ~JvmtiTagHashmap() {
286 if (_table != NULL) {
287 os::free((void*)_table);
288 _table = NULL;
289 }
290 }
291
292 // accessors
293 int size() const { return _size; }
294 JvmtiTagHashmapEntry** table() const { return _table; }
295 int entry_count() const { return _entry_count; }
296
297 // find an entry in the hashmap, returns NULL if not found.
298 inline JvmtiTagHashmapEntry* find(oop key) {
299 unsigned int h = hash(key);
300 JvmtiTagHashmapEntry* entry = _table[h];
301 while (entry != NULL) {
302 oop orig_key = JNIHandles::resolve(entry->object());
303 assert(orig_key != NULL, "jni weak reference cleared!!");
304 if (key == orig_key) {
305 break;
306 }
307 entry = entry->next();
308 }
309 return entry;
310 }
311
312
313 // add a new entry to hashmap
314 inline void add(oop key, JvmtiTagHashmapEntry* entry) {
315 assert(key != NULL, "checking");
316 assert(find(key) == NULL, "duplicate detected");
317 unsigned int h = hash(key);
318 JvmtiTagHashmapEntry* anchor = _table[h];
319 if (anchor == NULL) {
320 _table[h] = entry;
321 entry->set_next(NULL);
322 } else {
323 entry->set_next(anchor);
324 _table[h] = entry;
325 }
326
327 _entry_count++;
328 if (trace_threshold() > 0 && entry_count() >= trace_threshold()) {
329 assert(TraceJVMTIObjectTagging, "should only get here when tracing");
330 print_memory_usage();
331 compute_next_trace_threshold();
332 }
333
334 // if the number of entries exceed the threshold then resize
335 if (entry_count() > resize_threshold() && is_resizing_enabled()) {
336 resize();
337 }
338 }
339
340 // remove an entry with the given key.
341 inline JvmtiTagHashmapEntry* remove(oop key) {
342 unsigned int h = hash(key);
343 JvmtiTagHashmapEntry* entry = _table[h];
344 JvmtiTagHashmapEntry* prev = NULL;
345 while (entry != NULL) {
346 oop orig_key = JNIHandles::resolve(entry->object());
347 assert(orig_key != NULL, "jni weak reference cleared!!");
348 if (key == orig_key) {
349 break;
350 }
351 prev = entry;
352 entry = entry->next();
353 }
354 if (entry != NULL) {
355 remove(prev, h, entry);
356 }
357 return entry;
358 }
359
360 // iterate over all entries in the hashmap
361 void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
362 };
363
364 // possible hashmap sizes - odd primes that roughly double in size.
365 // To avoid excessive resizing the odd primes from 4801-76831 and
366 // 76831-307261 have been removed. The list must be terminated by -1.
367 int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891,
368 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
369
370
371 // A supporting class for iterating over all entries in Hashmap
372 class JvmtiTagHashmapEntryClosure {
373 public:
374 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
375 };
376
377
378 // iterate over all entries in the hashmap
379 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
380 for (int i=0; i<_size; i++) {
381 JvmtiTagHashmapEntry* entry = _table[i];
382 JvmtiTagHashmapEntry* prev = NULL;
383 while (entry != NULL) {
384 // obtain the next entry before invoking do_entry - this is
385 // necessary because do_entry may remove the entry from the
386 // hashmap.
387 JvmtiTagHashmapEntry* next = entry->next();
388 closure->do_entry(entry);
389 entry = next;
390 }
391 }
392 }
393
394 // debugging
395 void JvmtiTagHashmap::print_memory_usage() {
396 intptr_t p = (intptr_t)this;
397 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
398
399 // table + entries in KB
400 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
401 entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
402
403 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
404 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
405 entry_count(), hashmap_usage, weak_globals_usage);
406 }
407
408 // compute threshold for the next trace message
409 void JvmtiTagHashmap::compute_next_trace_threshold() {
410 if (trace_threshold() < medium_trace_threshold) {
411 _trace_threshold += small_trace_threshold;
412 } else {
413 if (trace_threshold() < large_trace_threshold) {
414 _trace_threshold += medium_trace_threshold;
415 } else {
416 _trace_threshold += large_trace_threshold;
417 }
418 }
419 }
420
421 // memory region for young generation
422 MemRegion JvmtiTagMap::_young_gen;
423
424 // get the memory region used for the young generation
425 void JvmtiTagMap::get_young_generation() {
426 CollectedHeap* ch = Universe::heap();
427 switch (ch->kind()) {
428 case (CollectedHeap::GenCollectedHeap): {
429 _young_gen = ((GenCollectedHeap*)ch)->get_gen(0)->reserved();
430 break;
431 }
432 #ifndef SERIALGC
433 case (CollectedHeap::ParallelScavengeHeap): {
434 _young_gen = ((ParallelScavengeHeap*)ch)->young_gen()->reserved();
435 break;
436 }
437 case (CollectedHeap::G1CollectedHeap): {
438 // Until a more satisfactory solution is implemented, all
439 // oops in the tag map will require rehash at each gc.
440 // This is a correct, if extremely inefficient solution.
441 // See RFE 6621729 for related commentary.
442 _young_gen = ch->reserved_region();
443 break;
444 }
445 #endif // !SERIALGC
446 default:
447 ShouldNotReachHere();
448 }
449 }
450
451 // returns true if oop is in the young generation
452 inline bool JvmtiTagMap::is_in_young(oop o) {
453 assert(_young_gen.start() != NULL, "checking");
454 void* p = (void*)o;
455 bool in_young = _young_gen.contains(p);
456 return in_young;
457 }
458
459 // returns the appropriate hashmap for a given object
460 inline JvmtiTagHashmap* JvmtiTagMap::hashmap_for(oop o) {
461 if (is_in_young(o)) {
462 return _hashmap[0];
463 } else {
464 return _hashmap[1];
465 }
466 }
467
468
469 // create a JvmtiTagMap
470 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
471 _env(env),
472 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
473 _free_entries(NULL),
474 _free_entries_count(0)
475 {
476 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
477 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
478
479 // create the hashmaps
480 for (int i=0; i<n_hashmaps; i++) {
481 _hashmap[i] = new JvmtiTagHashmap();
482 }
483
484 // get the memory region used by the young generation
485 get_young_generation();
486
487 // finally add us to the environment
488 ((JvmtiEnvBase *)env)->set_tag_map(this);
489 }
490
491
492 // destroy a JvmtiTagMap
493 JvmtiTagMap::~JvmtiTagMap() {
494
495 // no lock acquired as we assume the enclosing environment is
496 // also being destroryed.
497 ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
498
499 // iterate over the hashmaps and destroy each of the entries
500 for (int i=0; i<n_hashmaps; i++) {
501 JvmtiTagHashmap* hashmap = _hashmap[i];
502 JvmtiTagHashmapEntry** table = hashmap->table();
503 for (int j=0; j<hashmap->size(); j++) {
504 JvmtiTagHashmapEntry *entry = table[j];
505 while (entry != NULL) {
506 JvmtiTagHashmapEntry* next = entry->next();
507 jweak ref = entry->object();
508 JNIHandles::destroy_weak_global(ref);
509 delete entry;
510 entry = next;
511 }
512 }
513
514 // finally destroy the hashmap
515 delete hashmap;
516 }
517
518 // remove any entries on the free list
519 JvmtiTagHashmapEntry* entry = _free_entries;
520 while (entry != NULL) {
521 JvmtiTagHashmapEntry* next = entry->next();
522 delete entry;
523 entry = next;
524 }
525 }
526
527 // create a hashmap entry
528 // - if there's an entry on the (per-environment) free list then this
529 // is returned. Otherwise an new entry is allocated.
530 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(jweak ref, jlong tag) {
531 assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
532 JvmtiTagHashmapEntry* entry;
533 if (_free_entries == NULL) {
534 entry = new JvmtiTagHashmapEntry(ref, tag);
535 } else {
536 assert(_free_entries_count > 0, "mismatched _free_entries_count");
537 _free_entries_count--;
538 entry = _free_entries;
539 _free_entries = entry->next();
540 entry->init(ref, tag);
541 }
542 return entry;
543 }
544
545 // destroy an entry by returning it to the free list
546 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
547 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
548 // limit the size of the free list
549 if (_free_entries_count >= max_free_entries) {
550 delete entry;
551 } else {
552 entry->set_next(_free_entries);
553 _free_entries = entry;
554 _free_entries_count++;
555 }
556 }
557
558 // returns the tag map for the given environments. If the tag map
559 // doesn't exist then it is created.
560 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
561 JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map();
562 if (tag_map == NULL) {
563 MutexLocker mu(JvmtiThreadState_lock);
564 tag_map = ((JvmtiEnvBase *)env)->tag_map();
565 if (tag_map == NULL) {
566 tag_map = new JvmtiTagMap(env);
567 }
568 } else {
569 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
570 }
571 return tag_map;
572 }
573
574 // iterate over all entries in the tag map.
575 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
576 for (int i=0; i<n_hashmaps; i++) {
577 JvmtiTagHashmap* hashmap = _hashmap[i];
578 hashmap->entry_iterate(closure);
579 }
580 }
581
582 // returns true if the hashmaps are empty
583 bool JvmtiTagMap::is_empty() {
584 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
585 assert(n_hashmaps == 2, "not implemented");
586 return ((_hashmap[0]->entry_count() == 0) && (_hashmap[1]->entry_count() == 0));
587 }
588
589
590 // Return the tag value for an object, or 0 if the object is
591 // not tagged
592 //
593 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
594 JvmtiTagHashmapEntry* entry = tag_map->hashmap_for(o)->find(o);
595 if (entry == NULL) {
596 return 0;
597 } else {
598 return entry->tag();
599 }
600 }
601
602 // If the object is a java.lang.Class then return the klassOop,
603 // otherwise return the original object
604 static inline oop klassOop_if_java_lang_Class(oop o) {
605 if (o->klass() == SystemDictionary::Class_klass()) {
606 if (!java_lang_Class::is_primitive(o)) {
607 o = (oop)java_lang_Class::as_klassOop(o);
608 assert(o != NULL, "class for non-primitive mirror must exist");
609 }
610 }
611 return o;
612 }
613
614 // A CallbackWrapper is a support class for querying and tagging an object
615 // around a callback to a profiler. The constructor does pre-callback
616 // work to get the tag value, klass tag value, ... and the destructor
617 // does the post-callback work of tagging or untagging the object.
618 //
619 // {
620 // CallbackWrapper wrapper(tag_map, o);
621 //
622 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
623 //
624 // } // wrapper goes out of scope here which results in the destructor
625 // checking to see if the object has been tagged, untagged, or the
626 // tag value has changed.
627 //
628 class CallbackWrapper : public StackObj {
629 private:
630 JvmtiTagMap* _tag_map;
631 JvmtiTagHashmap* _hashmap;
632 JvmtiTagHashmapEntry* _entry;
633 oop _o;
634 jlong _obj_size;
635 jlong _obj_tag;
636 klassOop _klass; // the object's class
637 jlong _klass_tag;
638
639 protected:
640 JvmtiTagMap* tag_map() const { return _tag_map; }
641
642 // invoked post-callback to tag, untag, or update the tag of an object
643 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
644 JvmtiTagHashmapEntry* entry, jlong obj_tag);
645 public:
646 CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
647 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
648 "MT unsafe or must be VM thread");
649
650 // for Classes the klassOop is tagged
651 _o = klassOop_if_java_lang_Class(o);
652
653 // object size
654 _obj_size = _o->size() * wordSize;
655
656 // record the context
657 _tag_map = tag_map;
658 _hashmap = tag_map->hashmap_for(_o);
659 _entry = _hashmap->find(_o);
660
661 // get object tag
662 _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
663
664 // get the class and the class's tag value
665 if (_o == o) {
666 _klass = _o->klass();
667 } else {
668 // if the object represents a runtime class then use the
669 // tag for java.lang.Class
670 _klass = SystemDictionary::Class_klass();
671 }
672 _klass_tag = tag_for(tag_map, _klass);
673 }
674
675 ~CallbackWrapper() {
676 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
677 }
678
679 inline jlong* obj_tag_p() { return &_obj_tag; }
680 inline jlong obj_size() const { return _obj_size; }
681 inline jlong obj_tag() const { return _obj_tag; }
682 inline klassOop klass() const { return _klass; }
683 inline jlong klass_tag() const { return _klass_tag; }
684 };
685
686
687
688 // callback post-callback to tag, untag, or update the tag of an object
689 void inline CallbackWrapper::post_callback_tag_update(oop o,
690 JvmtiTagHashmap* hashmap,
691 JvmtiTagHashmapEntry* entry,
692 jlong obj_tag) {
693 if (entry == NULL) {
694 if (obj_tag != 0) {
695 // callback has tagged the object
696 assert(Thread::current()->is_VM_thread(), "must be VMThread");
697 HandleMark hm;
698 Handle h(o);
699 jweak ref = JNIHandles::make_weak_global(h);
700 entry = tag_map()->create_entry(ref, obj_tag);
701 hashmap->add(o, entry);
702 }
703 } else {
704 // object was previously tagged - the callback may have untagged
705 // the object or changed the tag value
706 if (obj_tag == 0) {
707 jweak ref = entry->object();
708
709 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
710 assert(entry_removed == entry, "checking");
711 tag_map()->destroy_entry(entry);
712
713 JNIHandles::destroy_weak_global(ref);
714 } else {
715 if (obj_tag != entry->tag()) {
716 entry->set_tag(obj_tag);
717 }
718 }
719 }
720 }
721
722 // An extended CallbackWrapper used when reporting an object reference
723 // to the agent.
724 //
725 // {
726 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
727 //
728 // (*callback)(wrapper.klass_tag(),
729 // wrapper.obj_size(),
730 // wrapper.obj_tag_p()
731 // wrapper.referrer_tag_p(), ...)
732 //
733 // } // wrapper goes out of scope here which results in the destructor
734 // checking to see if the referrer object has been tagged, untagged,
735 // or the tag value has changed.
736 //
737 class TwoOopCallbackWrapper : public CallbackWrapper {
738 private:
739 bool _is_reference_to_self;
740 JvmtiTagHashmap* _referrer_hashmap;
741 JvmtiTagHashmapEntry* _referrer_entry;
742 oop _referrer;
743 jlong _referrer_obj_tag;
744 jlong _referrer_klass_tag;
745 jlong* _referrer_tag_p;
746
747 bool is_reference_to_self() const { return _is_reference_to_self; }
748
749 public:
750 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
751 CallbackWrapper(tag_map, o)
752 {
753 // self reference needs to be handled in a special way
754 _is_reference_to_self = (referrer == o);
755
756 if (_is_reference_to_self) {
757 _referrer_klass_tag = klass_tag();
758 _referrer_tag_p = obj_tag_p();
759 } else {
760 // for Classes the klassOop is tagged
761 _referrer = klassOop_if_java_lang_Class(referrer);
762 // record the context
763 _referrer_hashmap = tag_map->hashmap_for(_referrer);
764 _referrer_entry = _referrer_hashmap->find(_referrer);
765
766 // get object tag
767 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
768 _referrer_tag_p = &_referrer_obj_tag;
769
770 // get referrer class tag.
771 klassOop k = (_referrer == referrer) ? // Check if referrer is a class...
772 _referrer->klass() // No, just get its class
773 : SystemDictionary::Class_klass(); // Yes, its class is Class
774 _referrer_klass_tag = tag_for(tag_map, k);
775 }
776 }
777
778 ~TwoOopCallbackWrapper() {
779 if (!is_reference_to_self()){
780 post_callback_tag_update(_referrer,
781 _referrer_hashmap,
782 _referrer_entry,
783 _referrer_obj_tag);
784 }
785 }
786
787 // address of referrer tag
788 // (for a self reference this will return the same thing as obj_tag_p())
789 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
790
791 // referrer's class tag
792 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
793 };
794
795 // tag an object
796 //
797 // This function is performance critical. If many threads attempt to tag objects
798 // around the same time then it's possible that the Mutex associated with the
799 // tag map will be a hot lock. Eliminating this lock will not eliminate the issue
800 // because creating a JNI weak reference requires acquiring a global lock also.
801 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
802 MutexLocker ml(lock());
803
804 // resolve the object
805 oop o = JNIHandles::resolve_non_null(object);
806
807 // for Classes we tag the klassOop
808 o = klassOop_if_java_lang_Class(o);
809
810 // see if the object is already tagged
811 JvmtiTagHashmap* hashmap = hashmap_for(o);
812 JvmtiTagHashmapEntry* entry = hashmap->find(o);
813
814 // if the object is not already tagged then we tag it
815 if (entry == NULL) {
816 if (tag != 0) {
817 HandleMark hm;
818 Handle h(o);
819 jweak ref = JNIHandles::make_weak_global(h);
820
821 // the object may have moved because make_weak_global may
822 // have blocked - thus it is necessary resolve the handle
823 // and re-hash the object.
824 o = h();
825 entry = create_entry(ref, tag);
826 hashmap_for(o)->add(o, entry);
827 } else {
828 // no-op
829 }
830 } else {
831 // if the object is already tagged then we either update
832 // the tag (if a new tag value has been provided)
833 // or remove the object if the new tag value is 0.
834 // Removing the object requires that we also delete the JNI
835 // weak ref to the object.
836 if (tag == 0) {
837 jweak ref = entry->object();
838 hashmap->remove(o);
839 destroy_entry(entry);
840 JNIHandles::destroy_weak_global(ref);
841 } else {
842 entry->set_tag(tag);
843 }
844 }
845 }
846
847 // get the tag for an object
848 jlong JvmtiTagMap::get_tag(jobject object) {
849 MutexLocker ml(lock());
850
851 // resolve the object
852 oop o = JNIHandles::resolve_non_null(object);
853
854 // for Classes get the tag from the klassOop
855 return tag_for(this, klassOop_if_java_lang_Class(o));
856 }
857
858
859 // Helper class used to describe the static or instance fields of a class.
860 // For each field it holds the field index (as defined by the JVMTI specification),
861 // the field type, and the offset.
862
863 class ClassFieldDescriptor: public CHeapObj {
864 private:
865 int _field_index;
866 int _field_offset;
867 char _field_type;
868 public:
869 ClassFieldDescriptor(int index, char type, int offset) :
870 _field_index(index), _field_type(type), _field_offset(offset) {
871 }
872 int field_index() const { return _field_index; }
873 char field_type() const { return _field_type; }
874 int field_offset() const { return _field_offset; }
875 };
876
877 class ClassFieldMap: public CHeapObj {
878 private:
879 enum {
880 initial_field_count = 5
881 };
882
883 // list of field descriptors
884 GrowableArray<ClassFieldDescriptor*>* _fields;
885
886 // constructor
887 ClassFieldMap();
888
889 // add a field
890 void add(int index, char type, int offset);
891
892 // returns the field count for the given class
893 static int compute_field_count(instanceKlassHandle ikh);
894
895 public:
896 ~ClassFieldMap();
897
898 // access
899 int field_count() { return _fields->length(); }
900 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
901
902 // functions to create maps of static or instance fields
903 static ClassFieldMap* create_map_of_static_fields(klassOop k);
904 static ClassFieldMap* create_map_of_instance_fields(oop obj);
905 };
906
907 ClassFieldMap::ClassFieldMap() {
908 _fields = new (ResourceObj::C_HEAP) GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
909 }
910
911 ClassFieldMap::~ClassFieldMap() {
912 for (int i=0; i<_fields->length(); i++) {
913 delete _fields->at(i);
914 }
915 delete _fields;
916 }
917
918 void ClassFieldMap::add(int index, char type, int offset) {
919 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
920 _fields->append(field);
921 }
922
923 // Returns a heap allocated ClassFieldMap to describe the static fields
924 // of the given class.
925 //
926 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(klassOop k) {
927 HandleMark hm;
928 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
929
930 // create the field map
931 ClassFieldMap* field_map = new ClassFieldMap();
932
933 FilteredFieldStream f(ikh, false, false);
934 int max_field_index = f.field_count()-1;
935
936 int index = 0;
937 for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
938 // ignore instance fields
939 if (!fld.access_flags().is_static()) {
940 continue;
941 }
942 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
943 }
944 return field_map;
945 }
946
947 // Returns a heap allocated ClassFieldMap to describe the instance fields
948 // of the given class. All instance fields are included (this means public
949 // and private fields declared in superclasses and superinterfaces too).
950 //
951 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
952 HandleMark hm;
953 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
954
955 // create the field map
956 ClassFieldMap* field_map = new ClassFieldMap();
957
958 FilteredFieldStream f(ikh, false, false);
959
960 int max_field_index = f.field_count()-1;
961
962 int index = 0;
963 for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
964 // ignore static fields
965 if (fld.access_flags().is_static()) {
966 continue;
967 }
968 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
969 }
970
971 return field_map;
972 }
973
974 // Helper class used to cache a ClassFileMap for the instance fields of
975 // a cache. A JvmtiCachedClassFieldMap can be cached by an instanceKlass during
976 // heap iteration and avoid creating a field map for each object in the heap
977 // (only need to create the map when the first instance of a class is encountered).
978 //
979 class JvmtiCachedClassFieldMap : public CHeapObj {
980 private:
981 enum {
982 initial_class_count = 200
983 };
984 ClassFieldMap* _field_map;
985
986 ClassFieldMap* field_map() const { return _field_map; }
987
988 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
989 ~JvmtiCachedClassFieldMap();
990
991 static GrowableArray<instanceKlass*>* _class_list;
992 static void add_to_class_list(instanceKlass* ik);
993
994 public:
995 // returns the field map for a given object (returning map cached
996 // by instanceKlass if possible
997 static ClassFieldMap* get_map_of_instance_fields(oop obj);
998
999 // removes the field map from all instanceKlasses - should be
1000 // called before VM operation completes
1001 static void clear_cache();
1002
1003 // returns the number of ClassFieldMap cached by instanceKlasses
1004 static int cached_field_map_count();
1005 };
1006
1007 GrowableArray<instanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
1008
1009 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
1010 _field_map = field_map;
1011 }
1012
1013 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
1014 if (_field_map != NULL) {
1015 delete _field_map;
1016 }
1017 }
1018
1019 // Marker class to ensure that the class file map cache is only used in a defined
1020 // scope.
1021 class ClassFieldMapCacheMark : public StackObj {
1022 private:
1023 static bool _is_active;
1024 public:
1025 ClassFieldMapCacheMark() {
1026 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1027 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
1028 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
1029 _is_active = true;
1030 }
1031 ~ClassFieldMapCacheMark() {
1032 JvmtiCachedClassFieldMap::clear_cache();
1033 _is_active = false;
1034 }
1035 static bool is_active() { return _is_active; }
1036 };
1037
1038 bool ClassFieldMapCacheMark::_is_active;
1039
1040
1041 // record that the given instanceKlass is caching a field map
1042 void JvmtiCachedClassFieldMap::add_to_class_list(instanceKlass* ik) {
1043 if (_class_list == NULL) {
1044 _class_list = new (ResourceObj::C_HEAP) GrowableArray<instanceKlass*>(initial_class_count, true);
1045 }
1046 _class_list->push(ik);
1047 }
1048
1049 // returns the instance field map for the given object
1050 // (returns field map cached by the instanceKlass if possible)
1051 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
1052 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1053 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
1054
1055 klassOop k = obj->klass();
1056 instanceKlass* ik = instanceKlass::cast(k);
1057
1058 // return cached map if possible
1059 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
1060 if (cached_map != NULL) {
1061 assert(cached_map->field_map() != NULL, "missing field list");
1062 return cached_map->field_map();
1063 } else {
1064 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
1065 cached_map = new JvmtiCachedClassFieldMap(field_map);
1066 ik->set_jvmti_cached_class_field_map(cached_map);
1067 add_to_class_list(ik);
1068 return field_map;
1069 }
1070 }
1071
1072 // remove the fields maps cached from all instanceKlasses
1073 void JvmtiCachedClassFieldMap::clear_cache() {
1074 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1075 if (_class_list != NULL) {
1076 for (int i = 0; i < _class_list->length(); i++) {
1077 instanceKlass* ik = _class_list->at(i);
1078 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
1079 assert(cached_map != NULL, "should not be NULL");
1080 ik->set_jvmti_cached_class_field_map(NULL);
1081 delete cached_map; // deletes the encapsulated field map
1082 }
1083 delete _class_list;
1084 _class_list = NULL;
1085 }
1086 }
1087
1088 // returns the number of ClassFieldMap cached by instanceKlasses
1089 int JvmtiCachedClassFieldMap::cached_field_map_count() {
1090 return (_class_list == NULL) ? 0 : _class_list->length();
1091 }
1092
1093 // helper function to indicate if an object is filtered by its tag or class tag
1094 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
1095 jlong klass_tag,
1096 int heap_filter) {
1097 // apply the heap filter
1098 if (obj_tag != 0) {
1099 // filter out tagged objects
1100 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
1101 } else {
1102 // filter out untagged objects
1103 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
1104 }
1105 if (klass_tag != 0) {
1106 // filter out objects with tagged classes
1107 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1108 } else {
1109 // filter out objects with untagged classes.
1110 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1111 }
1112 return false;
1113 }
1114
1115 // helper function to indicate if an object is filtered by a klass filter
1116 static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
1117 if (!klass_filter.is_null()) {
1118 if (obj->klass() != klass_filter()) {
1119 return true;
1120 }
1121 }
1122 return false;
1123 }
1124
1125 // helper function to tell if a field is a primitive field or not
1126 static inline bool is_primitive_field_type(char type) {
1127 return (type != 'L' && type != '[');
1128 }
1129
1130 // helper function to copy the value from location addr to jvalue.
1131 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1132 switch (value_type) {
1133 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1134 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
1135 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
1136 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
1137 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
1138 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
1139 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
1140 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
1141 default: ShouldNotReachHere();
1142 }
1143 }
1144
1145 // helper function to invoke string primitive value callback
1146 // returns visit control flags
1147 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1148 CallbackWrapper* wrapper,
1149 oop str,
1150 void* user_data)
1151 {
1152 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1153
1154 // get the string value and length
1155 // (string value may be offset from the base)
1156 int s_len = java_lang_String::length(str);
1157 typeArrayOop s_value = java_lang_String::value(str);
1158 int s_offset = java_lang_String::offset(str);
1159 jchar* value;
1160 if (s_len > 0) {
1161 value = s_value->char_at_addr(s_offset);
1162 } else {
1163 value = (jchar*) s_value->base(T_CHAR);
1164 }
1165
1166 // invoke the callback
1167 return (*cb)(wrapper->klass_tag(),
1168 wrapper->obj_size(),
1169 wrapper->obj_tag_p(),
1170 value,
1171 (jint)s_len,
1172 user_data);
1173 }
1174
1175 // helper function to invoke string primitive value callback
1176 // returns visit control flags
1177 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1178 CallbackWrapper* wrapper,
1179 oop obj,
1180 void* user_data)
1181 {
1182 assert(obj->is_typeArray(), "not a primitive array");
1183
1184 // get base address of first element
1185 typeArrayOop array = typeArrayOop(obj);
1186 BasicType type = typeArrayKlass::cast(array->klass())->element_type();
1187 void* elements = array->base(type);
1188
1189 // jvmtiPrimitiveType is defined so this mapping is always correct
1190 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1191
1192 return (*cb)(wrapper->klass_tag(),
1193 wrapper->obj_size(),
1194 wrapper->obj_tag_p(),
1195 (jint)array->length(),
1196 elem_type,
1197 elements,
1198 user_data);
1199 }
1200
1201 // helper function to invoke the primitive field callback for all static fields
1202 // of a given class
1203 static jint invoke_primitive_field_callback_for_static_fields
1204 (CallbackWrapper* wrapper,
1205 oop obj,
1206 jvmtiPrimitiveFieldCallback cb,
1207 void* user_data)
1208 {
1209 // for static fields only the index will be set
1210 static jvmtiHeapReferenceInfo reference_info = { 0 };
1211
1212 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1213 if (java_lang_Class::is_primitive(obj)) {
1214 return 0;
1215 }
1216 klassOop k = java_lang_Class::as_klassOop(obj);
1217 Klass* klass = k->klass_part();
1218
1219 // ignore classes for object and type arrays
1220 if (!klass->oop_is_instance()) {
1221 return 0;
1222 }
1223
1224 // ignore classes which aren't linked yet
1225 instanceKlass* ik = instanceKlass::cast(k);
1226 if (!ik->is_linked()) {
1227 return 0;
1228 }
1229
1230 // get the field map
1231 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
1232
1233 // invoke the callback for each static primitive field
1234 for (int i=0; i<field_map->field_count(); i++) {
1235 ClassFieldDescriptor* field = field_map->field_at(i);
1236
1237 // ignore non-primitive fields
1238 char type = field->field_type();
1239 if (!is_primitive_field_type(type)) {
1240 continue;
1241 }
1242 // one-to-one mapping
1243 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1244
1245 // get offset and field value
1246 int offset = field->field_offset();
1247 address addr = (address)k + offset;
1248 jvalue value;
1249 copy_to_jvalue(&value, addr, value_type);
1250
1251 // field index
1252 reference_info.field.index = field->field_index();
1253
1254 // invoke the callback
1255 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1256 &reference_info,
1257 wrapper->klass_tag(),
1258 wrapper->obj_tag_p(),
1259 value,
1260 value_type,
1261 user_data);
1262 if (res & JVMTI_VISIT_ABORT) {
1263 delete field_map;
1264 return res;
1265 }
1266 }
1267
1268 delete field_map;
1269 return 0;
1270 }
1271
1272 // helper function to invoke the primitive field callback for all instance fields
1273 // of a given object
1274 static jint invoke_primitive_field_callback_for_instance_fields(
1275 CallbackWrapper* wrapper,
1276 oop obj,
1277 jvmtiPrimitiveFieldCallback cb,
1278 void* user_data)
1279 {
1280 // for instance fields only the index will be set
1281 static jvmtiHeapReferenceInfo reference_info = { 0 };
1282
1283 // get the map of the instance fields
1284 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1285
1286 // invoke the callback for each instance primitive field
1287 for (int i=0; i<fields->field_count(); i++) {
1288 ClassFieldDescriptor* field = fields->field_at(i);
1289
1290 // ignore non-primitive fields
1291 char type = field->field_type();
1292 if (!is_primitive_field_type(type)) {
1293 continue;
1294 }
1295 // one-to-one mapping
1296 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1297
1298 // get offset and field value
1299 int offset = field->field_offset();
1300 address addr = (address)obj + offset;
1301 jvalue value;
1302 copy_to_jvalue(&value, addr, value_type);
1303
1304 // field index
1305 reference_info.field.index = field->field_index();
1306
1307 // invoke the callback
1308 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1309 &reference_info,
1310 wrapper->klass_tag(),
1311 wrapper->obj_tag_p(),
1312 value,
1313 value_type,
1314 user_data);
1315 if (res & JVMTI_VISIT_ABORT) {
1316 return res;
1317 }
1318 }
1319 return 0;
1320 }
1321
1322
1323 // VM operation to iterate over all objects in the heap (both reachable
1324 // and unreachable)
1325 class VM_HeapIterateOperation: public VM_Operation {
1326 private:
1327 ObjectClosure* _blk;
1328 public:
1329 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1330
1331 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1332 void doit() {
1333 // allows class files maps to be cached during iteration
1334 ClassFieldMapCacheMark cm;
1335
1336 // make sure that heap is parsable (fills TLABs with filler objects)
1337 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1338
1339 // Verify heap before iteration - if the heap gets corrupted then
1340 // JVMTI's IterateOverHeap will crash.
1341 if (VerifyBeforeIteration) {
1342 Universe::verify();
1343 }
1344
1345 // do the iteration
1346 // If this operation encounters a bad object when using CMS,
1347 // consider using safe_object_iterate() which avoids perm gen
1348 // objects that may contain bad references.
1349 Universe::heap()->object_iterate(_blk);
1350
1351 // when sharing is enabled we must iterate over the shared spaces
1352 if (UseSharedSpaces) {
1353 GenCollectedHeap* gch = GenCollectedHeap::heap();
1354 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
1355 gen->ro_space()->object_iterate(_blk);
1356 gen->rw_space()->object_iterate(_blk);
1357 }
1358 }
1359
1360 };
1361
1362
1363 // An ObjectClosure used to support the deprecated IterateOverHeap and
1364 // IterateOverInstancesOfClass functions
1365 class IterateOverHeapObjectClosure: public ObjectClosure {
1366 private:
1367 JvmtiTagMap* _tag_map;
1368 KlassHandle _klass;
1369 jvmtiHeapObjectFilter _object_filter;
1370 jvmtiHeapObjectCallback _heap_object_callback;
1371 const void* _user_data;
1372
1373 // accessors
1374 JvmtiTagMap* tag_map() const { return _tag_map; }
1375 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1376 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1377 KlassHandle klass() const { return _klass; }
1378 const void* user_data() const { return _user_data; }
1379
1380 // indicates if iteration has been aborted
1381 bool _iteration_aborted;
1382 bool is_iteration_aborted() const { return _iteration_aborted; }
1383 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1384
1385 public:
1386 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1387 KlassHandle klass,
1388 jvmtiHeapObjectFilter object_filter,
1389 jvmtiHeapObjectCallback heap_object_callback,
1390 const void* user_data) :
1391 _tag_map(tag_map),
1392 _klass(klass),
1393 _object_filter(object_filter),
1394 _heap_object_callback(heap_object_callback),
1395 _user_data(user_data),
1396 _iteration_aborted(false)
1397 {
1398 }
1399
1400 void do_object(oop o);
1401 };
1402
1403 // invoked for each object in the heap
1404 void IterateOverHeapObjectClosure::do_object(oop o) {
1405 // check if iteration has been halted
1406 if (is_iteration_aborted()) return;
1407
1408 // ignore any objects that aren't visible to profiler
1409 if (!ServiceUtil::visible_oop(o)) return;
1410
1411 // instanceof check when filtering by klass
1412 if (!klass().is_null() && !o->is_a(klass()())) {
1413 return;
1414 }
1415 // prepare for the calllback
1416 CallbackWrapper wrapper(tag_map(), o);
1417
1418 // if the object is tagged and we're only interested in untagged objects
1419 // then don't invoke the callback. Similiarly, if the object is untagged
1420 // and we're only interested in tagged objects we skip the callback.
1421 if (wrapper.obj_tag() != 0) {
1422 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1423 } else {
1424 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1425 }
1426
1427 // invoke the agent's callback
1428 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1429 wrapper.obj_size(),
1430 wrapper.obj_tag_p(),
1431 (void*)user_data());
1432 if (control == JVMTI_ITERATION_ABORT) {
1433 set_iteration_aborted(true);
1434 }
1435 }
1436
1437 // An ObjectClosure used to support the IterateThroughHeap function
1438 class IterateThroughHeapObjectClosure: public ObjectClosure {
1439 private:
1440 JvmtiTagMap* _tag_map;
1441 KlassHandle _klass;
1442 int _heap_filter;
1443 const jvmtiHeapCallbacks* _callbacks;
1444 const void* _user_data;
1445
1446 // accessor functions
1447 JvmtiTagMap* tag_map() const { return _tag_map; }
1448 int heap_filter() const { return _heap_filter; }
1449 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1450 KlassHandle klass() const { return _klass; }
1451 const void* user_data() const { return _user_data; }
1452
1453 // indicates if the iteration has been aborted
1454 bool _iteration_aborted;
1455 bool is_iteration_aborted() const { return _iteration_aborted; }
1456
1457 // used to check the visit control flags. If the abort flag is set
1458 // then we set the iteration aborted flag so that the iteration completes
1459 // without processing any further objects
1460 bool check_flags_for_abort(jint flags) {
1461 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1462 if (is_abort) {
1463 _iteration_aborted = true;
1464 }
1465 return is_abort;
1466 }
1467
1468 public:
1469 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1470 KlassHandle klass,
1471 int heap_filter,
1472 const jvmtiHeapCallbacks* heap_callbacks,
1473 const void* user_data) :
1474 _tag_map(tag_map),
1475 _klass(klass),
1476 _heap_filter(heap_filter),
1477 _callbacks(heap_callbacks),
1478 _user_data(user_data),
1479 _iteration_aborted(false)
1480 {
1481 }
1482
1483 void do_object(oop o);
1484 };
1485
1486 // invoked for each object in the heap
1487 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1488 // check if iteration has been halted
1489 if (is_iteration_aborted()) return;
1490
1491 // ignore any objects that aren't visible to profiler
1492 if (!ServiceUtil::visible_oop(obj)) return;
1493
1494 // apply class filter
1495 if (is_filtered_by_klass_filter(obj, klass())) return;
1496
1497 // prepare for callback
1498 CallbackWrapper wrapper(tag_map(), obj);
1499
1500 // check if filtered by the heap filter
1501 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1502 return;
1503 }
1504
1505 // for arrays we need the length, otherwise -1
1506 bool is_array = obj->is_array();
1507 int len = is_array ? arrayOop(obj)->length() : -1;
1508
1509 // invoke the object callback (if callback is provided)
1510 if (callbacks()->heap_iteration_callback != NULL) {
1511 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1512 jint res = (*cb)(wrapper.klass_tag(),
1513 wrapper.obj_size(),
1514 wrapper.obj_tag_p(),
1515 (jint)len,
1516 (void*)user_data());
1517 if (check_flags_for_abort(res)) return;
1518 }
1519
1520 // for objects and classes we report primitive fields if callback provided
1521 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1522 jint res;
1523 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1524 if (obj->klass() == SystemDictionary::Class_klass()) {
1525 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1526 obj,
1527 cb,
1528 (void*)user_data());
1529 } else {
1530 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1531 obj,
1532 cb,
1533 (void*)user_data());
1534 }
1535 if (check_flags_for_abort(res)) return;
1536 }
1537
1538 // string callback
1539 if (!is_array &&
1540 callbacks()->string_primitive_value_callback != NULL &&
1541 obj->klass() == SystemDictionary::String_klass()) {
1542 jint res = invoke_string_value_callback(
1543 callbacks()->string_primitive_value_callback,
1544 &wrapper,
1545 obj,
1546 (void*)user_data() );
1547 if (check_flags_for_abort(res)) return;
1548 }
1549
1550 // array callback
1551 if (is_array &&
1552 callbacks()->array_primitive_value_callback != NULL &&
1553 obj->is_typeArray()) {
1554 jint res = invoke_array_primitive_value_callback(
1555 callbacks()->array_primitive_value_callback,
1556 &wrapper,
1557 obj,
1558 (void*)user_data() );
1559 if (check_flags_for_abort(res)) return;
1560 }
1561 };
1562
1563
1564 // Deprecated function to iterate over all objects in the heap
1565 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1566 KlassHandle klass,
1567 jvmtiHeapObjectCallback heap_object_callback,
1568 const void* user_data)
1569 {
1570 MutexLocker ml(Heap_lock);
1571 IterateOverHeapObjectClosure blk(this,
1572 klass,
1573 object_filter,
1574 heap_object_callback,
1575 user_data);
1576 VM_HeapIterateOperation op(&blk);
1577 VMThread::execute(&op);
1578 }
1579
1580
1581 // Iterates over all objects in the heap
1582 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1583 KlassHandle klass,
1584 const jvmtiHeapCallbacks* callbacks,
1585 const void* user_data)
1586 {
1587 MutexLocker ml(Heap_lock);
1588 IterateThroughHeapObjectClosure blk(this,
1589 klass,
1590 heap_filter,
1591 callbacks,
1592 user_data);
1593 VM_HeapIterateOperation op(&blk);
1594 VMThread::execute(&op);
1595 }
1596
1597 // support class for get_objects_with_tags
1598
1599 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1600 private:
1601 JvmtiEnv* _env;
1602 jlong* _tags;
1603 jint _tag_count;
1604
1605 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1606 GrowableArray<uint64_t>* _tag_results; // collected tags
1607
1608 public:
1609 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1610 _env = env;
1611 _tags = (jlong*)tags;
1612 _tag_count = tag_count;
1613 _object_results = new (ResourceObj::C_HEAP) GrowableArray<jobject>(1,true);
1614 _tag_results = new (ResourceObj::C_HEAP) GrowableArray<uint64_t>(1,true);
1615 }
1616
1617 ~TagObjectCollector() {
1618 delete _object_results;
1619 delete _tag_results;
1620 }
1621
1622 // for each tagged object check if the tag value matches
1623 // - if it matches then we create a JNI local reference to the object
1624 // and record the reference and tag value.
1625 //
1626 void do_entry(JvmtiTagHashmapEntry* entry) {
1627 for (int i=0; i<_tag_count; i++) {
1628 if (_tags[i] == entry->tag()) {
1629 oop o = JNIHandles::resolve(entry->object());
1630 assert(o != NULL && o != JNIHandles::deleted_handle(), "sanity check");
1631
1632 // the mirror is tagged
1633 if (o->is_klass()) {
1634 klassOop k = (klassOop)o;
1635 o = Klass::cast(k)->java_mirror();
1636 }
1637
1638 jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1639 _object_results->append(ref);
1640 _tag_results->append((uint64_t)entry->tag());
1641 }
1642 }
1643 }
1644
1645 // return the results from the collection
1646 //
1647 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1648 jvmtiError error;
1649 int count = _object_results->length();
1650 assert(count >= 0, "sanity check");
1651
1652 // if object_result_ptr is not NULL then allocate the result and copy
1653 // in the object references.
1654 if (object_result_ptr != NULL) {
1655 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1656 if (error != JVMTI_ERROR_NONE) {
1657 return error;
1658 }
1659 for (int i=0; i<count; i++) {
1660 (*object_result_ptr)[i] = _object_results->at(i);
1661 }
1662 }
1663
1664 // if tag_result_ptr is not NULL then allocate the result and copy
1665 // in the tag values.
1666 if (tag_result_ptr != NULL) {
1667 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1668 if (error != JVMTI_ERROR_NONE) {
1669 if (object_result_ptr != NULL) {
1670 _env->Deallocate((unsigned char*)object_result_ptr);
1671 }
1672 return error;
1673 }
1674 for (int i=0; i<count; i++) {
1675 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1676 }
1677 }
1678
1679 *count_ptr = count;
1680 return JVMTI_ERROR_NONE;
1681 }
1682 };
1683
1684 // return the list of objects with the specified tags
1685 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1686 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1687
1688 TagObjectCollector collector(env(), tags, count);
1689 {
1690 // iterate over all tagged objects
1691 MutexLocker ml(lock());
1692 entry_iterate(&collector);
1693 }
1694 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1695 }
1696
1697
1698 // ObjectMarker is used to support the marking objects when walking the
1699 // heap.
1700 //
1701 // This implementation uses the existing mark bits in an object for
1702 // marking. Objects that are marked must later have their headers restored.
1703 // As most objects are unlocked and don't have their identity hash computed
1704 // we don't have to save their headers. Instead we save the headers that
1705 // are "interesting". Later when the headers are restored this implementation
1706 // restores all headers to their initial value and then restores the few
1707 // objects that had interesting headers.
1708 //
1709 // Future work: This implementation currently uses growable arrays to save
1710 // the oop and header of interesting objects. As an optimization we could
1711 // use the same technique as the GC and make use of the unused area
1712 // between top() and end().
1713 //
1714
1715 // An ObjectClosure used to restore the mark bits of an object
1716 class RestoreMarksClosure : public ObjectClosure {
1717 public:
1718 void do_object(oop o) {
1719 if (o != NULL) {
1720 markOop mark = o->mark();
1721 if (mark->is_marked()) {
1722 o->init_mark();
1723 }
1724 }
1725 }
1726 };
1727
1728 // ObjectMarker provides the mark and visited functions
1729 class ObjectMarker : AllStatic {
1730 private:
1731 // saved headers
1732 static GrowableArray<oop>* _saved_oop_stack;
1733 static GrowableArray<markOop>* _saved_mark_stack;
1734
1735 public:
1736 static void init(); // initialize
1737 static void done(); // clean-up
1738
1739 static inline void mark(oop o); // mark an object
1740 static inline bool visited(oop o); // check if object has been visited
1741 };
1742
1743 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1744 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1745
1746 // initialize ObjectMarker - prepares for object marking
1747 void ObjectMarker::init() {
1748 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1749
1750 // prepare heap for iteration
1751 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1752
1753 // create stacks for interesting headers
1754 _saved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(4000, true);
1755 _saved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
1756
1757 if (UseBiasedLocking) {
1758 BiasedLocking::preserve_marks();
1759 }
1760 }
1761
1762 // Object marking is done so restore object headers
1763 void ObjectMarker::done() {
1764 // iterate over all objects and restore the mark bits to
1765 // their initial value
1766 RestoreMarksClosure blk;
1767 Universe::heap()->object_iterate(&blk);
1768
1769 // When sharing is enabled we need to restore the headers of the objects
1770 // in the readwrite space too.
1771 if (UseSharedSpaces) {
1772 GenCollectedHeap* gch = GenCollectedHeap::heap();
1773 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
1774 gen->rw_space()->object_iterate(&blk);
1775 }
1776
1777 // now restore the interesting headers
1778 for (int i = 0; i < _saved_oop_stack->length(); i++) {
1779 oop o = _saved_oop_stack->at(i);
1780 markOop mark = _saved_mark_stack->at(i);
1781 o->set_mark(mark);
1782 }
1783
1784 if (UseBiasedLocking) {
1785 BiasedLocking::restore_marks();
1786 }
1787
1788 // free the stacks
1789 delete _saved_oop_stack;
1790 delete _saved_mark_stack;
1791 }
1792
1793 // mark an object
1794 inline void ObjectMarker::mark(oop o) {
1795 assert(Universe::heap()->is_in(o), "sanity check");
1796 assert(!o->mark()->is_marked(), "should only mark an object once");
1797
1798 // object's mark word
1799 markOop mark = o->mark();
1800
1801 if (mark->must_be_preserved(o)) {
1802 _saved_mark_stack->push(mark);
1803 _saved_oop_stack->push(o);
1804 }
1805
1806 // mark the object
1807 o->set_mark(markOopDesc::prototype()->set_marked());
1808 }
1809
1810 // return true if object is marked
1811 inline bool ObjectMarker::visited(oop o) {
1812 return o->mark()->is_marked();
1813 }
1814
1815 // Stack allocated class to help ensure that ObjectMarker is used
1816 // correctly. Constructor initializes ObjectMarker, destructor calls
1817 // ObjectMarker's done() function to restore object headers.
1818 class ObjectMarkerController : public StackObj {
1819 public:
1820 ObjectMarkerController() {
1821 ObjectMarker::init();
1822 }
1823 ~ObjectMarkerController() {
1824 ObjectMarker::done();
1825 }
1826 };
1827
1828
1829 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1830 // (not performance critical as only used for roots)
1831 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1832 switch (kind) {
1833 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1834 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1835 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR;
1836 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1837 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1838 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1839 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1840 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1841 }
1842 }
1843
1844 // Base class for all heap walk contexts. The base class maintains a flag
1845 // to indicate if the context is valid or not.
1846 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1847 private:
1848 bool _valid;
1849 public:
1850 HeapWalkContext(bool valid) { _valid = valid; }
1851 void invalidate() { _valid = false; }
1852 bool is_valid() const { return _valid; }
1853 };
1854
1855 // A basic heap walk context for the deprecated heap walking functions.
1856 // The context for a basic heap walk are the callbacks and fields used by
1857 // the referrer caching scheme.
1858 class BasicHeapWalkContext: public HeapWalkContext {
1859 private:
1860 jvmtiHeapRootCallback _heap_root_callback;
1861 jvmtiStackReferenceCallback _stack_ref_callback;
1862 jvmtiObjectReferenceCallback _object_ref_callback;
1863
1864 // used for caching
1865 oop _last_referrer;
1866 jlong _last_referrer_tag;
1867
1868 public:
1869 BasicHeapWalkContext() : HeapWalkContext(false) { }
1870
1871 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1872 jvmtiStackReferenceCallback stack_ref_callback,
1873 jvmtiObjectReferenceCallback object_ref_callback) :
1874 HeapWalkContext(true),
1875 _heap_root_callback(heap_root_callback),
1876 _stack_ref_callback(stack_ref_callback),
1877 _object_ref_callback(object_ref_callback),
1878 _last_referrer(NULL),
1879 _last_referrer_tag(0) {
1880 }
1881
1882 // accessors
1883 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1884 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1885 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1886
1887 oop last_referrer() const { return _last_referrer; }
1888 void set_last_referrer(oop referrer) { _last_referrer = referrer; }
1889 jlong last_referrer_tag() const { return _last_referrer_tag; }
1890 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1891 };
1892
1893 // The advanced heap walk context for the FollowReferences functions.
1894 // The context is the callbacks, and the fields used for filtering.
1895 class AdvancedHeapWalkContext: public HeapWalkContext {
1896 private:
1897 jint _heap_filter;
1898 KlassHandle _klass_filter;
1899 const jvmtiHeapCallbacks* _heap_callbacks;
1900
1901 public:
1902 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1903
1904 AdvancedHeapWalkContext(jint heap_filter,
1905 KlassHandle klass_filter,
1906 const jvmtiHeapCallbacks* heap_callbacks) :
1907 HeapWalkContext(true),
1908 _heap_filter(heap_filter),
1909 _klass_filter(klass_filter),
1910 _heap_callbacks(heap_callbacks) {
1911 }
1912
1913 // accessors
1914 jint heap_filter() const { return _heap_filter; }
1915 KlassHandle klass_filter() const { return _klass_filter; }
1916
1917 const jvmtiHeapReferenceCallback heap_reference_callback() const {
1918 return _heap_callbacks->heap_reference_callback;
1919 };
1920 const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1921 return _heap_callbacks->primitive_field_callback;
1922 }
1923 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1924 return _heap_callbacks->array_primitive_value_callback;
1925 }
1926 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1927 return _heap_callbacks->string_primitive_value_callback;
1928 }
1929 };
1930
1931 // The CallbackInvoker is a class with static functions that the heap walk can call
1932 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1933 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1934 // mode is for the newer FollowReferences function which supports a lot of
1935 // additional callbacks.
1936 class CallbackInvoker : AllStatic {
1937 private:
1938 // heap walk styles
1939 enum { basic, advanced };
1940 static int _heap_walk_type;
1941 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1942 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1943
1944 // context for basic style heap walk
1945 static BasicHeapWalkContext _basic_context;
1946 static BasicHeapWalkContext* basic_context() {
1947 assert(_basic_context.is_valid(), "invalid");
1948 return &_basic_context;
1949 }
1950
1951 // context for advanced style heap walk
1952 static AdvancedHeapWalkContext _advanced_context;
1953 static AdvancedHeapWalkContext* advanced_context() {
1954 assert(_advanced_context.is_valid(), "invalid");
1955 return &_advanced_context;
1956 }
1957
1958 // context needed for all heap walks
1959 static JvmtiTagMap* _tag_map;
1960 static const void* _user_data;
1961 static GrowableArray<oop>* _visit_stack;
1962
1963 // accessors
1964 static JvmtiTagMap* tag_map() { return _tag_map; }
1965 static const void* user_data() { return _user_data; }
1966 static GrowableArray<oop>* visit_stack() { return _visit_stack; }
1967
1968 // if the object hasn't been visited then push it onto the visit stack
1969 // so that it will be visited later
1970 static inline bool check_for_visit(oop obj) {
1971 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1972 return true;
1973 }
1974
1975 // invoke basic style callbacks
1976 static inline bool invoke_basic_heap_root_callback
1977 (jvmtiHeapRootKind root_kind, oop obj);
1978 static inline bool invoke_basic_stack_ref_callback
1979 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1980 int slot, oop obj);
1981 static inline bool invoke_basic_object_reference_callback
1982 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1983
1984 // invoke advanced style callbacks
1985 static inline bool invoke_advanced_heap_root_callback
1986 (jvmtiHeapReferenceKind ref_kind, oop obj);
1987 static inline bool invoke_advanced_stack_ref_callback
1988 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1989 jmethodID method, jlocation bci, jint slot, oop obj);
1990 static inline bool invoke_advanced_object_reference_callback
1991 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1992
1993 // used to report the value of primitive fields
1994 static inline bool report_primitive_field
1995 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1996
1997 public:
1998 // initialize for basic mode
1999 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
2000 GrowableArray<oop>* visit_stack,
2001 const void* user_data,
2002 BasicHeapWalkContext context);
2003
2004 // initialize for advanced mode
2005 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
2006 GrowableArray<oop>* visit_stack,
2007 const void* user_data,
2008 AdvancedHeapWalkContext context);
2009
2010 // functions to report roots
2011 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
2012 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
2013 jmethodID m, oop o);
2014 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
2015 jmethodID method, jlocation bci, jint slot, oop o);
2016
2017 // functions to report references
2018 static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
2019 static inline bool report_class_reference(oop referrer, oop referree);
2020 static inline bool report_class_loader_reference(oop referrer, oop referree);
2021 static inline bool report_signers_reference(oop referrer, oop referree);
2022 static inline bool report_protection_domain_reference(oop referrer, oop referree);
2023 static inline bool report_superclass_reference(oop referrer, oop referree);
2024 static inline bool report_interface_reference(oop referrer, oop referree);
2025 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
2026 static inline bool report_field_reference(oop referrer, oop referree, jint slot);
2027 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
2028 static inline bool report_primitive_array_values(oop array);
2029 static inline bool report_string_value(oop str);
2030 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
2031 static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
2032 };
2033
2034 // statics
2035 int CallbackInvoker::_heap_walk_type;
2036 BasicHeapWalkContext CallbackInvoker::_basic_context;
2037 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
2038 JvmtiTagMap* CallbackInvoker::_tag_map;
2039 const void* CallbackInvoker::_user_data;
2040 GrowableArray<oop>* CallbackInvoker::_visit_stack;
2041
2042 // initialize for basic heap walk (IterateOverReachableObjects et al)
2043 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
2044 GrowableArray<oop>* visit_stack,
2045 const void* user_data,
2046 BasicHeapWalkContext context) {
2047 _tag_map = tag_map;
2048 _visit_stack = visit_stack;
2049 _user_data = user_data;
2050 _basic_context = context;
2051 _advanced_context.invalidate(); // will trigger assertion if used
2052 _heap_walk_type = basic;
2053 }
2054
2055 // initialize for advanced heap walk (FollowReferences)
2056 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
2057 GrowableArray<oop>* visit_stack,
2058 const void* user_data,
2059 AdvancedHeapWalkContext context) {
2060 _tag_map = tag_map;
2061 _visit_stack = visit_stack;
2062 _user_data = user_data;
2063 _advanced_context = context;
2064 _basic_context.invalidate(); // will trigger assertion if used
2065 _heap_walk_type = advanced;
2066 }
2067
2068
2069 // invoke basic style heap root callback
2070 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
2071 assert(ServiceUtil::visible_oop(obj), "checking");
2072
2073 // if we heap roots should be reported
2074 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
2075 if (cb == NULL) {
2076 return check_for_visit(obj);
2077 }
2078
2079 CallbackWrapper wrapper(tag_map(), obj);
2080 jvmtiIterationControl control = (*cb)(root_kind,
2081 wrapper.klass_tag(),
2082 wrapper.obj_size(),
2083 wrapper.obj_tag_p(),
2084 (void*)user_data());
2085 // push root to visit stack when following references
2086 if (control == JVMTI_ITERATION_CONTINUE &&
2087 basic_context()->object_ref_callback() != NULL) {
2088 visit_stack()->push(obj);
2089 }
2090 return control != JVMTI_ITERATION_ABORT;
2091 }
2092
2093 // invoke basic style stack ref callback
2094 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
2095 jlong thread_tag,
2096 jint depth,
2097 jmethodID method,
2098 jint slot,
2099 oop obj) {
2100 assert(ServiceUtil::visible_oop(obj), "checking");
2101
2102 // if we stack refs should be reported
2103 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
2104 if (cb == NULL) {
2105 return check_for_visit(obj);
2106 }
2107
2108 CallbackWrapper wrapper(tag_map(), obj);
2109 jvmtiIterationControl control = (*cb)(root_kind,
2110 wrapper.klass_tag(),
2111 wrapper.obj_size(),
2112 wrapper.obj_tag_p(),
2113 thread_tag,
2114 depth,
2115 method,
2116 slot,
2117 (void*)user_data());
2118 // push root to visit stack when following references
2119 if (control == JVMTI_ITERATION_CONTINUE &&
2120 basic_context()->object_ref_callback() != NULL) {
2121 visit_stack()->push(obj);
2122 }
2123 return control != JVMTI_ITERATION_ABORT;
2124 }
2125
2126 // invoke basic style object reference callback
2127 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2128 oop referrer,
2129 oop referree,
2130 jint index) {
2131
2132 assert(ServiceUtil::visible_oop(referrer), "checking");
2133 assert(ServiceUtil::visible_oop(referree), "checking");
2134
2135 BasicHeapWalkContext* context = basic_context();
2136
2137 // callback requires the referrer's tag. If it's the same referrer
2138 // as the last call then we use the cached value.
2139 jlong referrer_tag;
2140 if (referrer == context->last_referrer()) {
2141 referrer_tag = context->last_referrer_tag();
2142 } else {
2143 referrer_tag = tag_for(tag_map(), klassOop_if_java_lang_Class(referrer));
2144 }
2145
2146 // do the callback
2147 CallbackWrapper wrapper(tag_map(), referree);
2148 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2149 jvmtiIterationControl control = (*cb)(ref_kind,
2150 wrapper.klass_tag(),
2151 wrapper.obj_size(),
2152 wrapper.obj_tag_p(),
2153 referrer_tag,
2154 index,
2155 (void*)user_data());
2156
2157 // record referrer and referrer tag. For self-references record the
2158 // tag value from the callback as this might differ from referrer_tag.
2159 context->set_last_referrer(referrer);
2160 if (referrer == referree) {
2161 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2162 } else {
2163 context->set_last_referrer_tag(referrer_tag);
2164 }
2165
2166 if (control == JVMTI_ITERATION_CONTINUE) {
2167 return check_for_visit(referree);
2168 } else {
2169 return control != JVMTI_ITERATION_ABORT;
2170 }
2171 }
2172
2173 // invoke advanced style heap root callback
2174 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2175 oop obj) {
2176 assert(ServiceUtil::visible_oop(obj), "checking");
2177
2178 AdvancedHeapWalkContext* context = advanced_context();
2179
2180 // check that callback is provided
2181 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2182 if (cb == NULL) {
2183 return check_for_visit(obj);
2184 }
2185
2186 // apply class filter
2187 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2188 return check_for_visit(obj);
2189 }
2190
2191 // setup the callback wrapper
2192 CallbackWrapper wrapper(tag_map(), obj);
2193
2194 // apply tag filter
2195 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2196 wrapper.klass_tag(),
2197 context->heap_filter())) {
2198 return check_for_visit(obj);
2199 }
2200
2201 // for arrays we need the length, otherwise -1
2202 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2203
2204 // invoke the callback
2205 jint res = (*cb)(ref_kind,
2206 NULL, // referrer info
2207 wrapper.klass_tag(),
2208 0, // referrer_class_tag is 0 for heap root
2209 wrapper.obj_size(),
2210 wrapper.obj_tag_p(),
2211 NULL, // referrer_tag_p
2212 len,
2213 (void*)user_data());
2214 if (res & JVMTI_VISIT_ABORT) {
2215 return false;// referrer class tag
2216 }
2217 if (res & JVMTI_VISIT_OBJECTS) {
2218 check_for_visit(obj);
2219 }
2220 return true;
2221 }
2222
2223 // report a reference from a thread stack to an object
2224 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2225 jlong thread_tag,
2226 jlong tid,
2227 int depth,
2228 jmethodID method,
2229 jlocation bci,
2230 jint slot,
2231 oop obj) {
2232 assert(ServiceUtil::visible_oop(obj), "checking");
2233
2234 AdvancedHeapWalkContext* context = advanced_context();
2235
2236 // check that callback is provider
2237 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2238 if (cb == NULL) {
2239 return check_for_visit(obj);
2240 }
2241
2242 // apply class filter
2243 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2244 return check_for_visit(obj);
2245 }
2246
2247 // setup the callback wrapper
2248 CallbackWrapper wrapper(tag_map(), obj);
2249
2250 // apply tag filter
2251 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2252 wrapper.klass_tag(),
2253 context->heap_filter())) {
2254 return check_for_visit(obj);
2255 }
2256
2257 // setup the referrer info
2258 jvmtiHeapReferenceInfo reference_info;
2259 reference_info.stack_local.thread_tag = thread_tag;
2260 reference_info.stack_local.thread_id = tid;
2261 reference_info.stack_local.depth = depth;
2262 reference_info.stack_local.method = method;
2263 reference_info.stack_local.location = bci;
2264 reference_info.stack_local.slot = slot;
2265
2266 // for arrays we need the length, otherwise -1
2267 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2268
2269 // call into the agent
2270 int res = (*cb)(ref_kind,
2271 &reference_info,
2272 wrapper.klass_tag(),
2273 0, // referrer_class_tag is 0 for heap root (stack)
2274 wrapper.obj_size(),
2275 wrapper.obj_tag_p(),
2276 NULL, // referrer_tag is 0 for root
2277 len,
2278 (void*)user_data());
2279
2280 if (res & JVMTI_VISIT_ABORT) {
2281 return false;
2282 }
2283 if (res & JVMTI_VISIT_OBJECTS) {
2284 check_for_visit(obj);
2285 }
2286 return true;
2287 }
2288
2289 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2290 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2291 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2292 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2293 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2294 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2295 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2296 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2297
2298 // invoke the object reference callback to report a reference
2299 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2300 oop referrer,
2301 oop obj,
2302 jint index)
2303 {
2304 // field index is only valid field in reference_info
2305 static jvmtiHeapReferenceInfo reference_info = { 0 };
2306
2307 assert(ServiceUtil::visible_oop(referrer), "checking");
2308 assert(ServiceUtil::visible_oop(obj), "checking");
2309
2310 AdvancedHeapWalkContext* context = advanced_context();
2311
2312 // check that callback is provider
2313 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2314 if (cb == NULL) {
2315 return check_for_visit(obj);
2316 }
2317
2318 // apply class filter
2319 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2320 return check_for_visit(obj);
2321 }
2322
2323 // setup the callback wrapper
2324 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2325
2326 // apply tag filter
2327 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2328 wrapper.klass_tag(),
2329 context->heap_filter())) {
2330 return check_for_visit(obj);
2331 }
2332
2333 // field index is only valid field in reference_info
2334 reference_info.field.index = index;
2335
2336 // for arrays we need the length, otherwise -1
2337 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2338
2339 // invoke the callback
2340 int res = (*cb)(ref_kind,
2341 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2342 wrapper.klass_tag(),
2343 wrapper.referrer_klass_tag(),
2344 wrapper.obj_size(),
2345 wrapper.obj_tag_p(),
2346 wrapper.referrer_tag_p(),
2347 len,
2348 (void*)user_data());
2349
2350 if (res & JVMTI_VISIT_ABORT) {
2351 return false;
2352 }
2353 if (res & JVMTI_VISIT_OBJECTS) {
2354 check_for_visit(obj);
2355 }
2356 return true;
2357 }
2358
2359 // report a "simple root"
2360 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2361 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2362 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2363 assert(ServiceUtil::visible_oop(obj), "checking");
2364
2365 if (is_basic_heap_walk()) {
2366 // map to old style root kind
2367 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2368 return invoke_basic_heap_root_callback(root_kind, obj);
2369 } else {
2370 assert(is_advanced_heap_walk(), "wrong heap walk type");
2371 return invoke_advanced_heap_root_callback(kind, obj);
2372 }
2373 }
2374
2375
2376 // invoke the primitive array values
2377 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2378 assert(obj->is_typeArray(), "not a primitive array");
2379
2380 AdvancedHeapWalkContext* context = advanced_context();
2381 assert(context->array_primitive_value_callback() != NULL, "no callback");
2382
2383 // apply class filter
2384 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2385 return true;
2386 }
2387
2388 CallbackWrapper wrapper(tag_map(), obj);
2389
2390 // apply tag filter
2391 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2392 wrapper.klass_tag(),
2393 context->heap_filter())) {
2394 return true;
2395 }
2396
2397 // invoke the callback
2398 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2399 &wrapper,
2400 obj,
2401 (void*)user_data());
2402 return (!(res & JVMTI_VISIT_ABORT));
2403 }
2404
2405 // invoke the string value callback
2406 inline bool CallbackInvoker::report_string_value(oop str) {
2407 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2408
2409 AdvancedHeapWalkContext* context = advanced_context();
2410 assert(context->string_primitive_value_callback() != NULL, "no callback");
2411
2412 // apply class filter
2413 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2414 return true;
2415 }
2416
2417 CallbackWrapper wrapper(tag_map(), str);
2418
2419 // apply tag filter
2420 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2421 wrapper.klass_tag(),
2422 context->heap_filter())) {
2423 return true;
2424 }
2425
2426 // invoke the callback
2427 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2428 &wrapper,
2429 str,
2430 (void*)user_data());
2431 return (!(res & JVMTI_VISIT_ABORT));
2432 }
2433
2434 // invoke the primitive field callback
2435 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2436 oop obj,
2437 jint index,
2438 address addr,
2439 char type)
2440 {
2441 // for primitive fields only the index will be set
2442 static jvmtiHeapReferenceInfo reference_info = { 0 };
2443
2444 AdvancedHeapWalkContext* context = advanced_context();
2445 assert(context->primitive_field_callback() != NULL, "no callback");
2446
2447 // apply class filter
2448 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2449 return true;
2450 }
2451
2452 CallbackWrapper wrapper(tag_map(), obj);
2453
2454 // apply tag filter
2455 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2456 wrapper.klass_tag(),
2457 context->heap_filter())) {
2458 return true;
2459 }
2460
2461 // the field index in the referrer
2462 reference_info.field.index = index;
2463
2464 // map the type
2465 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2466
2467 // setup the jvalue
2468 jvalue value;
2469 copy_to_jvalue(&value, addr, value_type);
2470
2471 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2472 int res = (*cb)(ref_kind,
2473 &reference_info,
2474 wrapper.klass_tag(),
2475 wrapper.obj_tag_p(),
2476 value,
2477 value_type,
2478 (void*)user_data());
2479 return (!(res & JVMTI_VISIT_ABORT));
2480 }
2481
2482
2483 // instance field
2484 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2485 jint index,
2486 address value,
2487 char type) {
2488 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2489 obj,
2490 index,
2491 value,
2492 type);
2493 }
2494
2495 // static field
2496 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2497 jint index,
2498 address value,
2499 char type) {
2500 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2501 obj,
2502 index,
2503 value,
2504 type);
2505 }
2506
2507 // report a JNI local (root object) to the profiler
2508 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2509 if (is_basic_heap_walk()) {
2510 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2511 thread_tag,
2512 depth,
2513 m,
2514 -1,
2515 obj);
2516 } else {
2517 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2518 thread_tag, tid,
2519 depth,
2520 m,
2521 (jlocation)-1,
2522 -1,
2523 obj);
2524 }
2525 }
2526
2527
2528 // report a local (stack reference, root object)
2529 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2530 jlong tid,
2531 jint depth,
2532 jmethodID method,
2533 jlocation bci,
2534 jint slot,
2535 oop obj) {
2536 if (is_basic_heap_walk()) {
2537 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2538 thread_tag,
2539 depth,
2540 method,
2541 slot,
2542 obj);
2543 } else {
2544 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2545 thread_tag,
2546 tid,
2547 depth,
2548 method,
2549 bci,
2550 slot,
2551 obj);
2552 }
2553 }
2554
2555 // report an object referencing a class.
2556 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2557 if (is_basic_heap_walk()) {
2558 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2559 } else {
2560 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2561 }
2562 }
2563
2564 // report a class referencing its class loader.
2565 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2566 if (is_basic_heap_walk()) {
2567 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2568 } else {
2569 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2570 }
2571 }
2572
2573 // report a class referencing its signers.
2574 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2575 if (is_basic_heap_walk()) {
2576 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2577 } else {
2578 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2579 }
2580 }
2581
2582 // report a class referencing its protection domain..
2583 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2584 if (is_basic_heap_walk()) {
2585 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2586 } else {
2587 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2588 }
2589 }
2590
2591 // report a class referencing its superclass.
2592 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2593 if (is_basic_heap_walk()) {
2594 // Send this to be consistent with past implementation
2595 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2596 } else {
2597 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2598 }
2599 }
2600
2601 // report a class referencing one of its interfaces.
2602 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2603 if (is_basic_heap_walk()) {
2604 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2605 } else {
2606 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2607 }
2608 }
2609
2610 // report a class referencing one of its static fields.
2611 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2612 if (is_basic_heap_walk()) {
2613 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2614 } else {
2615 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2616 }
2617 }
2618
2619 // report an array referencing an element object
2620 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2621 if (is_basic_heap_walk()) {
2622 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2623 } else {
2624 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2625 }
2626 }
2627
2628 // report an object referencing an instance field object
2629 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2630 if (is_basic_heap_walk()) {
2631 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2632 } else {
2633 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2634 }
2635 }
2636
2637 // report an array referencing an element object
2638 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2639 if (is_basic_heap_walk()) {
2640 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2641 } else {
2642 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2643 }
2644 }
2645
2646 // A supporting closure used to process simple roots
2647 class SimpleRootsClosure : public OopClosure {
2648 private:
2649 jvmtiHeapReferenceKind _kind;
2650 bool _continue;
2651
2652 jvmtiHeapReferenceKind root_kind() { return _kind; }
2653
2654 public:
2655 void set_kind(jvmtiHeapReferenceKind kind) {
2656 _kind = kind;
2657 _continue = true;
2658 }
2659
2660 inline bool stopped() {
2661 return !_continue;
2662 }
2663
2664 void do_oop(oop* obj_p) {
2665 // iteration has terminated
2666 if (stopped()) {
2667 return;
2668 }
2669
2670 // ignore null or deleted handles
2671 oop o = *obj_p;
2672 if (o == NULL || o == JNIHandles::deleted_handle()) {
2673 return;
2674 }
2675
2676 jvmtiHeapReferenceKind kind = root_kind();
2677
2678 // many roots are Klasses so we use the java mirror
2679 if (o->is_klass()) {
2680 klassOop k = (klassOop)o;
2681 o = Klass::cast(k)->java_mirror();
2682 } else {
2683
2684 // SystemDictionary::always_strong_oops_do reports the application
2685 // class loader as a root. We want this root to be reported as
2686 // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2687 if (o->is_instance() && root_kind() == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2688 kind = JVMTI_HEAP_REFERENCE_OTHER;
2689 }
2690 }
2691
2692 // some objects are ignored - in the case of simple
2693 // roots it's mostly symbolOops that we are skipping
2694 // here.
2695 if (!ServiceUtil::visible_oop(o)) {
2696 return;
2697 }
2698
2699 // invoke the callback
2700 _continue = CallbackInvoker::report_simple_root(kind, o);
2701
2702 }
2703 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2704 };
2705
2706 // A supporting closure used to process JNI locals
2707 class JNILocalRootsClosure : public OopClosure {
2708 private:
2709 jlong _thread_tag;
2710 jlong _tid;
2711 jint _depth;
2712 jmethodID _method;
2713 bool _continue;
2714 public:
2715 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2716 _thread_tag = thread_tag;
2717 _tid = tid;
2718 _depth = depth;
2719 _method = method;
2720 _continue = true;
2721 }
2722
2723 inline bool stopped() {
2724 return !_continue;
2725 }
2726
2727 void do_oop(oop* obj_p) {
2728 // iteration has terminated
2729 if (stopped()) {
2730 return;
2731 }
2732
2733 // ignore null or deleted handles
2734 oop o = *obj_p;
2735 if (o == NULL || o == JNIHandles::deleted_handle()) {
2736 return;
2737 }
2738
2739 if (!ServiceUtil::visible_oop(o)) {
2740 return;
2741 }
2742
2743 // invoke the callback
2744 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2745 }
2746 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2747 };
2748
2749
2750 // A VM operation to iterate over objects that are reachable from
2751 // a set of roots or an initial object.
2752 //
2753 // For VM_HeapWalkOperation the set of roots used is :-
2754 //
2755 // - All JNI global references
2756 // - All inflated monitors
2757 // - All classes loaded by the boot class loader (or all classes
2758 // in the event that class unloading is disabled)
2759 // - All java threads
2760 // - For each java thread then all locals and JNI local references
2761 // on the thread's execution stack
2762 // - All visible/explainable objects from Universes::oops_do
2763 //
2764 class VM_HeapWalkOperation: public VM_Operation {
2765 private:
2766 enum {
2767 initial_visit_stack_size = 4000
2768 };
2769
2770 bool _is_advanced_heap_walk; // indicates FollowReferences
2771 JvmtiTagMap* _tag_map;
2772 Handle _initial_object;
2773 GrowableArray<oop>* _visit_stack; // the visit stack
2774
2775 bool _collecting_heap_roots; // are we collecting roots
2776 bool _following_object_refs; // are we following object references
2777
2778 bool _reporting_primitive_fields; // optional reporting
2779 bool _reporting_primitive_array_values;
2780 bool _reporting_string_values;
2781
2782 GrowableArray<oop>* create_visit_stack() {
2783 return new (ResourceObj::C_HEAP) GrowableArray<oop>(initial_visit_stack_size, true);
2784 }
2785
2786 // accessors
2787 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2788 JvmtiTagMap* tag_map() const { return _tag_map; }
2789 Handle initial_object() const { return _initial_object; }
2790
2791 bool is_following_references() const { return _following_object_refs; }
2792
2793 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2794 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2795 bool is_reporting_string_values() const { return _reporting_string_values; }
2796
2797 GrowableArray<oop>* visit_stack() const { return _visit_stack; }
2798
2799 // iterate over the various object types
2800 inline bool iterate_over_array(oop o);
2801 inline bool iterate_over_type_array(oop o);
2802 inline bool iterate_over_class(klassOop o);
2803 inline bool iterate_over_object(oop o);
2804
2805 // root collection
2806 inline bool collect_simple_roots();
2807 inline bool collect_stack_roots();
2808 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2809
2810 // visit an object
2811 inline bool visit(oop o);
2812
2813 public:
2814 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2815 Handle initial_object,
2816 BasicHeapWalkContext callbacks,
2817 const void* user_data);
2818
2819 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2820 Handle initial_object,
2821 AdvancedHeapWalkContext callbacks,
2822 const void* user_data);
2823
2824 ~VM_HeapWalkOperation();
2825
2826 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2827 void doit();
2828 };
2829
2830
2831 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2832 Handle initial_object,
2833 BasicHeapWalkContext callbacks,
2834 const void* user_data) {
2835 _is_advanced_heap_walk = false;
2836 _tag_map = tag_map;
2837 _initial_object = initial_object;
2838 _following_object_refs = (callbacks.object_ref_callback() != NULL);
2839 _reporting_primitive_fields = false;
2840 _reporting_primitive_array_values = false;
2841 _reporting_string_values = false;
2842 _visit_stack = create_visit_stack();
2843
2844
2845 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2846 }
2847
2848 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2849 Handle initial_object,
2850 AdvancedHeapWalkContext callbacks,
2851 const void* user_data) {
2852 _is_advanced_heap_walk = true;
2853 _tag_map = tag_map;
2854 _initial_object = initial_object;
2855 _following_object_refs = true;
2856 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2857 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2858 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2859 _visit_stack = create_visit_stack();
2860
2861 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2862 }
2863
2864 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2865 if (_following_object_refs) {
2866 assert(_visit_stack != NULL, "checking");
2867 delete _visit_stack;
2868 _visit_stack = NULL;
2869 }
2870 }
2871
2872 // an array references its class and has a reference to
2873 // each element in the array
2874 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2875 objArrayOop array = objArrayOop(o);
2876 if (array->klass() == Universe::systemObjArrayKlassObj()) {
2877 // filtered out
2878 return true;
2879 }
2880
2881 // array reference to its class
2882 oop mirror = objArrayKlass::cast(array->klass())->java_mirror();
2883 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2884 return false;
2885 }
2886
2887 // iterate over the array and report each reference to a
2888 // non-null element
2889 for (int index=0; index<array->length(); index++) {
2890 oop elem = array->obj_at(index);
2891 if (elem == NULL) {
2892 continue;
2893 }
2894
2895 // report the array reference o[index] = elem
2896 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2897 return false;
2898 }
2899 }
2900 return true;
2901 }
2902
2903 // a type array references its class
2904 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2905 klassOop k = o->klass();
2906 oop mirror = Klass::cast(k)->java_mirror();
2907 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2908 return false;
2909 }
2910
2911 // report the array contents if required
2912 if (is_reporting_primitive_array_values()) {
2913 if (!CallbackInvoker::report_primitive_array_values(o)) {
2914 return false;
2915 }
2916 }
2917 return true;
2918 }
2919
2920 // verify that a static oop field is in range
2921 static inline bool verify_static_oop(instanceKlass* ik,
2922 klassOop k, int offset) {
2923 address obj_p = (address)k + offset;
2924 address start = (address)ik->start_of_static_fields();
2925 address end = start + (ik->static_oop_field_size() * heapOopSize);
2926 assert(end >= start, "sanity check");
2927
2928 if (obj_p >= start && obj_p < end) {
2929 return true;
2930 } else {
2931 return false;
2932 }
2933 }
2934
2935 // a class references its super class, interfaces, class loader, ...
2936 // and finally its static fields
2937 inline bool VM_HeapWalkOperation::iterate_over_class(klassOop k) {
2938 int i;
2939 Klass* klass = klassOop(k)->klass_part();
2940
2941 if (klass->oop_is_instance()) {
2942 instanceKlass* ik = instanceKlass::cast(k);
2943
2944 // ignore the class if it's has been initialized yet
2945 if (!ik->is_linked()) {
2946 return true;
2947 }
2948
2949 // get the java mirror
2950 oop mirror = klass->java_mirror();
2951
2952 // super (only if something more interesting than java.lang.Object)
2953 klassOop java_super = ik->java_super();
2954 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2955 oop super = Klass::cast(java_super)->java_mirror();
2956 if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2957 return false;
2958 }
2959 }
2960
2961 // class loader
2962 oop cl = ik->class_loader();
2963 if (cl != NULL) {
2964 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2965 return false;
2966 }
2967 }
2968
2969 // protection domain
2970 oop pd = ik->protection_domain();
2971 if (pd != NULL) {
2972 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2973 return false;
2974 }
2975 }
2976
2977 // signers
2978 oop signers = ik->signers();
2979 if (signers != NULL) {
2980 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2981 return false;
2982 }
2983 }
2984
2985 // references from the constant pool
2986 {
2987 const constantPoolOop pool = ik->constants();
2988 for (int i = 1; i < pool->length(); i++) {
2989 constantTag tag = pool->tag_at(i).value();
2990 if (tag.is_string() || tag.is_klass()) {
2991 oop entry;
2992 if (tag.is_string()) {
2993 entry = pool->resolved_string_at(i);
2994 assert(java_lang_String::is_instance(entry), "must be string");
2995 } else {
2996 entry = Klass::cast(pool->resolved_klass_at(i))->java_mirror();
2997 }
2998 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2999 return false;
3000 }
3001 }
3002 }
3003 }
3004
3005 // interfaces
3006 // (These will already have been reported as references from the constant pool
3007 // but are specified by IterateOverReachableObjects and must be reported).
3008 objArrayOop interfaces = ik->local_interfaces();
3009 for (i = 0; i < interfaces->length(); i++) {
3010 oop interf = Klass::cast((klassOop)interfaces->obj_at(i))->java_mirror();
3011 if (interf == NULL) {
3012 continue;
3013 }
3014 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
3015 return false;
3016 }
3017 }
3018
3019 // iterate over the static fields
3020
3021 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
3022 for (i=0; i<field_map->field_count(); i++) {
3023 ClassFieldDescriptor* field = field_map->field_at(i);
3024 char type = field->field_type();
3025 if (!is_primitive_field_type(type)) {
3026 oop fld_o = k->obj_field(field->field_offset());
3027 assert(verify_static_oop(ik, k, field->field_offset()), "sanity check");
3028 if (fld_o != NULL) {
3029 int slot = field->field_index();
3030 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
3031 delete field_map;
3032 return false;
3033 }
3034 }
3035 } else {
3036 if (is_reporting_primitive_fields()) {
3037 address addr = (address)k + field->field_offset();
3038 int slot = field->field_index();
3039 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
3040 delete field_map;
3041 return false;
3042 }
3043 }
3044 }
3045 }
3046 delete field_map;
3047
3048 return true;
3049 }
3050
3051 return true;
3052 }
3053
3054 // an object references a class and its instance fields
3055 // (static fields are ignored here as we report these as
3056 // references from the class).
3057 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
3058 // reference to the class
3059 if (!CallbackInvoker::report_class_reference(o, Klass::cast(o->klass())->java_mirror())) {
3060 return false;
3061 }
3062
3063 // iterate over instance fields
3064 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
3065 for (int i=0; i<field_map->field_count(); i++) {
3066 ClassFieldDescriptor* field = field_map->field_at(i);
3067 char type = field->field_type();
3068 if (!is_primitive_field_type(type)) {
3069 oop fld_o = o->obj_field(field->field_offset());
3070 if (fld_o != NULL) {
3071 // reflection code may have a reference to a klassOop.
3072 // - see sun.reflect.UnsafeStaticFieldAccessorImpl and sun.misc.Unsafe
3073 if (fld_o->is_klass()) {
3074 klassOop k = (klassOop)fld_o;
3075 fld_o = Klass::cast(k)->java_mirror();
3076 }
3077 int slot = field->field_index();
3078 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
3079 return false;
3080 }
3081 }
3082 } else {
3083 if (is_reporting_primitive_fields()) {
3084 // primitive instance field
3085 address addr = (address)o + field->field_offset();
3086 int slot = field->field_index();
3087 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
3088 return false;
3089 }
3090 }
3091 }
3092 }
3093
3094 // if the object is a java.lang.String
3095 if (is_reporting_string_values() &&
3096 o->klass() == SystemDictionary::String_klass()) {
3097 if (!CallbackInvoker::report_string_value(o)) {
3098 return false;
3099 }
3100 }
3101 return true;
3102 }
3103
3104
3105 // collects all simple (non-stack) roots.
3106 // if there's a heap root callback provided then the callback is
3107 // invoked for each simple root.
3108 // if an object reference callback is provided then all simple
3109 // roots are pushed onto the marking stack so that they can be
3110 // processed later
3111 //
3112 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3113 SimpleRootsClosure blk;
3114
3115 // JNI globals
3116 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3117 JNIHandles::oops_do(&blk);
3118 if (blk.stopped()) {
3119 return false;
3120 }
3121
3122 // Preloaded classes and loader from the system dictionary
3123 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3124 SystemDictionary::always_strong_oops_do(&blk);
3125 if (blk.stopped()) {
3126 return false;
3127 }
3128
3129 // Inflated monitors
3130 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3131 ObjectSynchronizer::oops_do(&blk);
3132 if (blk.stopped()) {
3133 return false;
3134 }
3135
3136 // Threads
3137 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3138 oop threadObj = thread->threadObj();
3139 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3140 bool cont = CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, threadObj);
3141 if (!cont) {
3142 return false;
3143 }
3144 }
3145 }
3146
3147 // Other kinds of roots maintained by HotSpot
3148 // Many of these won't be visible but others (such as instances of important
3149 // exceptions) will be visible.
3150 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3151 Universe::oops_do(&blk);
3152
3153 // If there are any non-perm roots in the code cache, visit them.
3154 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3155 CodeBlobToOopClosure look_in_blobs(&blk, false);
3156 CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3157
3158 return true;
3159 }
3160
3161 // Walk the stack of a given thread and find all references (locals
3162 // and JNI calls) and report these as stack references
3163 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3164 JNILocalRootsClosure* blk)
3165 {
3166 oop threadObj = java_thread->threadObj();
3167 assert(threadObj != NULL, "sanity check");
3168
3169 // only need to get the thread's tag once per thread
3170 jlong thread_tag = tag_for(_tag_map, threadObj);
3171
3172 // also need the thread id
3173 jlong tid = java_lang_Thread::thread_id(threadObj);
3174
3175
3176 if (java_thread->has_last_Java_frame()) {
3177
3178 // vframes are resource allocated
3179 Thread* current_thread = Thread::current();
3180 ResourceMark rm(current_thread);
3181 HandleMark hm(current_thread);
3182
3183 RegisterMap reg_map(java_thread);
3184 frame f = java_thread->last_frame();
3185 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3186
3187 bool is_top_frame = true;
3188 int depth = 0;
3189 frame* last_entry_frame = NULL;
3190
3191 while (vf != NULL) {
3192 if (vf->is_java_frame()) {
3193
3194 // java frame (interpreted, compiled, ...)
3195 javaVFrame *jvf = javaVFrame::cast(vf);
3196
3197 // the jmethodID
3198 jmethodID method = jvf->method()->jmethod_id();
3199
3200 if (!(jvf->method()->is_native())) {
3201 jlocation bci = (jlocation)jvf->bci();
3202 StackValueCollection* locals = jvf->locals();
3203 for (int slot=0; slot<locals->size(); slot++) {
3204 if (locals->at(slot)->type() == T_OBJECT) {
3205 oop o = locals->obj_at(slot)();
3206 if (o == NULL) {
3207 continue;
3208 }
3209
3210 // stack reference
3211 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3212 bci, slot, o)) {
3213 return false;
3214 }
3215 }
3216 }
3217 } else {
3218 blk->set_context(thread_tag, tid, depth, method);
3219 if (is_top_frame) {
3220 // JNI locals for the top frame.
3221 java_thread->active_handles()->oops_do(blk);
3222 } else {
3223 if (last_entry_frame != NULL) {
3224 // JNI locals for the entry frame
3225 assert(last_entry_frame->is_entry_frame(), "checking");
3226 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3227 }
3228 }
3229 }
3230 last_entry_frame = NULL;
3231 depth++;
3232 } else {
3233 // externalVFrame - for an entry frame then we report the JNI locals
3234 // when we find the corresponding javaVFrame
3235 frame* fr = vf->frame_pointer();
3236 assert(fr != NULL, "sanity check");
3237 if (fr->is_entry_frame()) {
3238 last_entry_frame = fr;
3239 }
3240 }
3241
3242 vf = vf->sender();
3243 is_top_frame = false;
3244 }
3245 } else {
3246 // no last java frame but there may be JNI locals
3247 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3248 java_thread->active_handles()->oops_do(blk);
3249 }
3250 return true;
3251 }
3252
3253
3254 // collects all stack roots - for each thread it walks the execution
3255 // stack to find all references and local JNI refs.
3256 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3257 JNILocalRootsClosure blk;
3258 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3259 oop threadObj = thread->threadObj();
3260 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3261 if (!collect_stack_roots(thread, &blk)) {
3262 return false;
3263 }
3264 }
3265 }
3266 return true;
3267 }
3268
3269 // visit an object
3270 // first mark the object as visited
3271 // second get all the outbound references from this object (in other words, all
3272 // the objects referenced by this object).
3273 //
3274 bool VM_HeapWalkOperation::visit(oop o) {
3275 // mark object as visited
3276 assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3277 ObjectMarker::mark(o);
3278
3279 // instance
3280 if (o->is_instance()) {
3281 if (o->klass() == SystemDictionary::Class_klass()) {
3282 o = klassOop_if_java_lang_Class(o);
3283 if (o->is_klass()) {
3284 // a java.lang.Class
3285 return iterate_over_class(klassOop(o));
3286 }
3287 } else {
3288 return iterate_over_object(o);
3289 }
3290 }
3291
3292 // object array
3293 if (o->is_objArray()) {
3294 return iterate_over_array(o);
3295 }
3296
3297 // type array
3298 if (o->is_typeArray()) {
3299 return iterate_over_type_array(o);
3300 }
3301
3302 return true;
3303 }
3304
3305 void VM_HeapWalkOperation::doit() {
3306 ResourceMark rm;
3307 ObjectMarkerController marker;
3308 ClassFieldMapCacheMark cm;
3309
3310 assert(visit_stack()->is_empty(), "visit stack must be empty");
3311
3312 // the heap walk starts with an initial object or the heap roots
3313 if (initial_object().is_null()) {
3314 if (!collect_simple_roots()) return;
3315 if (!collect_stack_roots()) return;
3316 } else {
3317 visit_stack()->push(initial_object()());
3318 }
3319
3320 // object references required
3321 if (is_following_references()) {
3322
3323 // visit each object until all reachable objects have been
3324 // visited or the callback asked to terminate the iteration.
3325 while (!visit_stack()->is_empty()) {
3326 oop o = visit_stack()->pop();
3327 if (!ObjectMarker::visited(o)) {
3328 if (!visit(o)) {
3329 break;
3330 }
3331 }
3332 }
3333 }
3334 }
3335
3336 // iterate over all objects that are reachable from a set of roots
3337 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3338 jvmtiStackReferenceCallback stack_ref_callback,
3339 jvmtiObjectReferenceCallback object_ref_callback,
3340 const void* user_data) {
3341 MutexLocker ml(Heap_lock);
3342 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3343 VM_HeapWalkOperation op(this, Handle(), context, user_data);
3344 VMThread::execute(&op);
3345 }
3346
3347 // iterate over all objects that are reachable from a given object
3348 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3349 jvmtiObjectReferenceCallback object_ref_callback,
3350 const void* user_data) {
3351 oop obj = JNIHandles::resolve(object);
3352 Handle initial_object(Thread::current(), obj);
3353
3354 MutexLocker ml(Heap_lock);
3355 BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3356 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3357 VMThread::execute(&op);
3358 }
3359
3360 // follow references from an initial object or the GC roots
3361 void JvmtiTagMap::follow_references(jint heap_filter,
3362 KlassHandle klass,
3363 jobject object,
3364 const jvmtiHeapCallbacks* callbacks,
3365 const void* user_data)
3366 {
3367 oop obj = JNIHandles::resolve(object);
3368 Handle initial_object(Thread::current(), obj);
3369
3370 MutexLocker ml(Heap_lock);
3371 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3372 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3373 VMThread::execute(&op);
3374 }
3375
3376
3377 // called post-GC
3378 // - for each JVMTI environment with an object tag map, call its rehash
3379 // function to re-sync with the new object locations.
3380 void JvmtiTagMap::gc_epilogue(bool full) {
3381 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
3382 if (JvmtiEnv::environments_might_exist()) {
3383 // re-obtain the memory region for the young generation (might
3384 // changed due to adaptive resizing policy)
3385 get_young_generation();
3386
3387 JvmtiEnvIterator it;
3388 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3389 JvmtiTagMap* tag_map = env->tag_map();
3390 if (tag_map != NULL && !tag_map->is_empty()) {
3391 TraceTime t(full ? "JVMTI Full Rehash " : "JVMTI Rehash ", TraceJVMTIObjectTagging);
3392 if (full) {
3393 tag_map->rehash(0, n_hashmaps);
3394 } else {
3395 tag_map->rehash(0, 0); // tag map for young gen only
3396 }
3397 }
3398 }
3399 }
3400 }
3401
3402 // CMS has completed referencing processing so we may have JNI weak refs
3403 // to objects in the CMS generation that have been GC'ed.
3404 void JvmtiTagMap::cms_ref_processing_epilogue() {
3405 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
3406 assert(UseConcMarkSweepGC, "should only be used with CMS");
3407 if (JvmtiEnv::environments_might_exist()) {
3408 JvmtiEnvIterator it;
3409 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3410 JvmtiTagMap* tag_map = ((JvmtiEnvBase *)env)->tag_map();
3411 if (tag_map != NULL && !tag_map->is_empty()) {
3412 TraceTime t("JVMTI Rehash (CMS) ", TraceJVMTIObjectTagging);
3413 tag_map->rehash(1, n_hashmaps); // assume CMS not used in young gen
3414 }
3415 }
3416 }
3417 }
3418
3419
3420 // For each entry in the hashmaps 'start' to 'end' :
3421 //
3422 // 1. resolve the JNI weak reference
3423 //
3424 // 2. If it resolves to NULL it means the object has been freed so the entry
3425 // is removed, the weak reference destroyed, and the object free event is
3426 // posted (if enabled).
3427 //
3428 // 3. If the weak reference resolves to an object then we re-hash the object
3429 // to see if it has moved or has been promoted (from the young to the old
3430 // generation for example).
3431 //
3432 void JvmtiTagMap::rehash(int start, int end) {
3433
3434 // does this environment have the OBJECT_FREE event enabled
3435 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3436
3437 // counters used for trace message
3438 int freed = 0;
3439 int moved = 0;
3440 int promoted = 0;
3441
3442 // we assume there are two hashmaps - one for the young generation
3443 // and the other for all other spaces.
3444 assert(n_hashmaps == 2, "not implemented");
3445 JvmtiTagHashmap* young_hashmap = _hashmap[0];
3446 JvmtiTagHashmap* other_hashmap = _hashmap[1];
3447
3448 // reenable sizing (if disabled)
3449 young_hashmap->set_resizing_enabled(true);
3450 other_hashmap->set_resizing_enabled(true);
3451
3452 // when re-hashing the hashmap corresponding to the young generation we
3453 // collect the entries corresponding to objects that have been promoted.
3454 JvmtiTagHashmapEntry* promoted_entries = NULL;
3455
3456 if (end >= n_hashmaps) {
3457 end = n_hashmaps - 1;
3458 }
3459
3460 for (int i=start; i <= end; i++) {
3461 JvmtiTagHashmap* hashmap = _hashmap[i];
3462
3463 // if the hashmap is empty then we can skip it
3464 if (hashmap->_entry_count == 0) {
3465 continue;
3466 }
3467
3468 // now iterate through each entry in the table
3469
3470 JvmtiTagHashmapEntry** table = hashmap->table();
3471 int size = hashmap->size();
3472
3473 for (int pos=0; pos<size; pos++) {
3474 JvmtiTagHashmapEntry* entry = table[pos];
3475 JvmtiTagHashmapEntry* prev = NULL;
3476
3477 while (entry != NULL) {
3478 JvmtiTagHashmapEntry* next = entry->next();
3479
3480 jweak ref = entry->object();
3481 oop oop = JNIHandles::resolve(ref);
3482
3483 // has object been GC'ed
3484 if (oop == NULL) {
3485 // grab the tag
3486 jlong tag = entry->tag();
3487 guarantee(tag != 0, "checking");
3488
3489 // remove GC'ed entry from hashmap and return the
3490 // entry to the free list
3491 hashmap->remove(prev, pos, entry);
3492 destroy_entry(entry);
3493
3494 // destroy the weak ref
3495 JNIHandles::destroy_weak_global(ref);
3496
3497 // post the event to the profiler
3498 if (post_object_free) {
3499 JvmtiExport::post_object_free(env(), tag);
3500 }
3501
3502 freed++;
3503 entry = next;
3504 continue;
3505 }
3506
3507 // if this is the young hashmap then the object is either promoted
3508 // or moved.
3509 // if this is the other hashmap then the object is moved.
3510
3511 bool same_gen;
3512 if (i == 0) {
3513 assert(hashmap == young_hashmap, "checking");
3514 same_gen = is_in_young(oop);
3515 } else {
3516 same_gen = true;
3517 }
3518
3519
3520 if (same_gen) {
3521 // if the object has moved then re-hash it and move its
3522 // entry to its new location.
3523 unsigned int new_pos = JvmtiTagHashmap::hash(oop, size);
3524 if (new_pos != (unsigned int)pos) {
3525 if (prev == NULL) {
3526 table[pos] = next;
3527 } else {
3528 prev->set_next(next);
3529 }
3530 entry->set_next(table[new_pos]);
3531 table[new_pos] = entry;
3532 moved++;
3533 } else {
3534 // object didn't move
3535 prev = entry;
3536 }
3537 } else {
3538 // object has been promoted so remove the entry from the
3539 // young hashmap
3540 assert(hashmap == young_hashmap, "checking");
3541 hashmap->remove(prev, pos, entry);
3542
3543 // move the entry to the promoted list
3544 entry->set_next(promoted_entries);
3545 promoted_entries = entry;
3546 }
3547
3548 entry = next;
3549 }
3550 }
3551 }
3552
3553
3554 // add the entries, corresponding to the promoted objects, to the
3555 // other hashmap.
3556 JvmtiTagHashmapEntry* entry = promoted_entries;
3557 while (entry != NULL) {
3558 oop o = JNIHandles::resolve(entry->object());
3559 assert(hashmap_for(o) == other_hashmap, "checking");
3560 JvmtiTagHashmapEntry* next = entry->next();
3561 other_hashmap->add(o, entry);
3562 entry = next;
3563 promoted++;
3564 }
3565
3566 // stats
3567 if (TraceJVMTIObjectTagging) {
3568 int total_moves = promoted + moved;
3569
3570 int post_total = 0;
3571 for (int i=0; i<n_hashmaps; i++) {
3572 post_total += _hashmap[i]->_entry_count;
3573 }
3574 int pre_total = post_total + freed;
3575
3576 tty->print("(%d->%d, %d freed, %d promoted, %d total moves)",
3577 pre_total, post_total, freed, promoted, total_moves);
3578 }
3579 }