Thu, 24 May 2018 17:06:56 +0800
Merge
1 /*
2 * Copyright (c) 2003, 2013, 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 */
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/instanceMirrorKlass.hpp"
31 #include "oops/objArrayKlass.hpp"
32 #include "oops/oop.inline2.hpp"
33 #include "prims/jvmtiEventController.hpp"
34 #include "prims/jvmtiEventController.inline.hpp"
35 #include "prims/jvmtiExport.hpp"
36 #include "prims/jvmtiImpl.hpp"
37 #include "prims/jvmtiTagMap.hpp"
38 #include "runtime/biasedLocking.hpp"
39 #include "runtime/javaCalls.hpp"
40 #include "runtime/jniHandles.hpp"
41 #include "runtime/mutex.hpp"
42 #include "runtime/mutexLocker.hpp"
43 #include "runtime/reflectionUtils.hpp"
44 #include "runtime/vframe.hpp"
45 #include "runtime/vmThread.hpp"
46 #include "runtime/vm_operations.hpp"
47 #include "services/serviceUtil.hpp"
48 #include "utilities/macros.hpp"
49 #if INCLUDE_ALL_GCS
50 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
51 #endif // INCLUDE_ALL_GCS
53 // JvmtiTagHashmapEntry
54 //
55 // Each entry encapsulates a reference to the tagged object
56 // and the tag value. In addition an entry includes a next pointer which
57 // is used to chain entries together.
59 class JvmtiTagHashmapEntry : public CHeapObj<mtInternal> {
60 private:
61 friend class JvmtiTagMap;
63 oop _object; // tagged object
64 jlong _tag; // the tag
65 JvmtiTagHashmapEntry* _next; // next on the list
67 inline void init(oop object, jlong tag) {
68 _object = object;
69 _tag = tag;
70 _next = NULL;
71 }
73 // constructor
74 JvmtiTagHashmapEntry(oop object, jlong tag) { init(object, tag); }
76 public:
78 // accessor methods
79 inline oop object() const { return _object; }
80 inline oop* object_addr() { return &_object; }
81 inline jlong tag() const { return _tag; }
83 inline void set_tag(jlong tag) {
84 assert(tag != 0, "can't be zero");
85 _tag = tag;
86 }
88 inline JvmtiTagHashmapEntry* next() const { return _next; }
89 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; }
90 };
93 // JvmtiTagHashmap
94 //
95 // A hashmap is essentially a table of pointers to entries. Entries
96 // are hashed to a location, or position in the table, and then
97 // chained from that location. The "key" for hashing is address of
98 // the object, or oop. The "value" is the tag value.
99 //
100 // A hashmap maintains a count of the number entries in the hashmap
101 // and resizes if the number of entries exceeds a given threshold.
102 // The threshold is specified as a percentage of the size - for
103 // example a threshold of 0.75 will trigger the hashmap to resize
104 // if the number of entries is >75% of table size.
105 //
106 // A hashmap provides functions for adding, removing, and finding
107 // entries. It also provides a function to iterate over all entries
108 // in the hashmap.
110 class JvmtiTagHashmap : public CHeapObj<mtInternal> {
111 private:
112 friend class JvmtiTagMap;
114 enum {
115 small_trace_threshold = 10000, // threshold for tracing
116 medium_trace_threshold = 100000,
117 large_trace_threshold = 1000000,
118 initial_trace_threshold = small_trace_threshold
119 };
121 static int _sizes[]; // array of possible hashmap sizes
122 int _size; // actual size of the table
123 int _size_index; // index into size table
125 int _entry_count; // number of entries in the hashmap
127 float _load_factor; // load factor as a % of the size
128 int _resize_threshold; // computed threshold to trigger resizing.
129 bool _resizing_enabled; // indicates if hashmap can resize
131 int _trace_threshold; // threshold for trace messages
133 JvmtiTagHashmapEntry** _table; // the table of entries.
135 // private accessors
136 int resize_threshold() const { return _resize_threshold; }
137 int trace_threshold() const { return _trace_threshold; }
139 // initialize the hashmap
140 void init(int size_index=0, float load_factor=4.0f) {
141 int initial_size = _sizes[size_index];
142 _size_index = size_index;
143 _size = initial_size;
144 _entry_count = 0;
145 if (TraceJVMTIObjectTagging) {
146 _trace_threshold = initial_trace_threshold;
147 } else {
148 _trace_threshold = -1;
149 }
150 _load_factor = load_factor;
151 _resize_threshold = (int)(_load_factor * _size);
152 _resizing_enabled = true;
153 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
154 _table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
155 if (_table == NULL) {
156 vm_exit_out_of_memory(s, OOM_MALLOC_ERROR,
157 "unable to allocate initial hashtable for jvmti object tags");
158 }
159 for (int i=0; i<initial_size; i++) {
160 _table[i] = NULL;
161 }
162 }
164 // hash a given key (oop) with the specified size
165 static unsigned int hash(oop key, int size) {
166 // shift right to get better distribution (as these bits will be zero
167 // with aligned addresses)
168 unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key));
169 #ifdef _LP64
170 return (addr >> 3) % size;
171 #else
172 return (addr >> 2) % size;
173 #endif
174 }
176 // hash a given key (oop)
177 unsigned int hash(oop key) {
178 return hash(key, _size);
179 }
181 // resize the hashmap - allocates a large table and re-hashes
182 // all entries into the new table.
183 void resize() {
184 int new_size_index = _size_index+1;
185 int new_size = _sizes[new_size_index];
186 if (new_size < 0) {
187 // hashmap already at maximum capacity
188 return;
189 }
191 // allocate new table
192 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
193 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s, mtInternal);
194 if (new_table == NULL) {
195 warning("unable to allocate larger hashtable for jvmti object tags");
196 set_resizing_enabled(false);
197 return;
198 }
200 // initialize new table
201 int i;
202 for (i=0; i<new_size; i++) {
203 new_table[i] = NULL;
204 }
206 // rehash all entries into the new table
207 for (i=0; i<_size; i++) {
208 JvmtiTagHashmapEntry* entry = _table[i];
209 while (entry != NULL) {
210 JvmtiTagHashmapEntry* next = entry->next();
211 oop key = entry->object();
212 assert(key != NULL, "jni weak reference cleared!!");
213 unsigned int h = hash(key, new_size);
214 JvmtiTagHashmapEntry* anchor = new_table[h];
215 if (anchor == NULL) {
216 new_table[h] = entry;
217 entry->set_next(NULL);
218 } else {
219 entry->set_next(anchor);
220 new_table[h] = entry;
221 }
222 entry = next;
223 }
224 }
226 // free old table and update settings.
227 os::free((void*)_table);
228 _table = new_table;
229 _size_index = new_size_index;
230 _size = new_size;
232 // compute new resize threshold
233 _resize_threshold = (int)(_load_factor * _size);
234 }
237 // internal remove function - remove an entry at a given position in the
238 // table.
239 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
240 assert(pos >= 0 && pos < _size, "out of range");
241 if (prev == NULL) {
242 _table[pos] = entry->next();
243 } else {
244 prev->set_next(entry->next());
245 }
246 assert(_entry_count > 0, "checking");
247 _entry_count--;
248 }
250 // resizing switch
251 bool is_resizing_enabled() const { return _resizing_enabled; }
252 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; }
254 // debugging
255 void print_memory_usage();
256 void compute_next_trace_threshold();
258 public:
260 // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
261 // The preferred size is rounded down to an actual size.
262 JvmtiTagHashmap(int size, float load_factor=0.0f) {
263 int i=0;
264 while (_sizes[i] < size) {
265 if (_sizes[i] < 0) {
266 assert(i > 0, "sanity check");
267 i--;
268 break;
269 }
270 i++;
271 }
273 // if a load factor is specified then use it, otherwise use default
274 if (load_factor > 0.01f) {
275 init(i, load_factor);
276 } else {
277 init(i);
278 }
279 }
281 // create a JvmtiTagHashmap with default settings
282 JvmtiTagHashmap() {
283 init();
284 }
286 // release table when JvmtiTagHashmap destroyed
287 ~JvmtiTagHashmap() {
288 if (_table != NULL) {
289 os::free((void*)_table);
290 _table = NULL;
291 }
292 }
294 // accessors
295 int size() const { return _size; }
296 JvmtiTagHashmapEntry** table() const { return _table; }
297 int entry_count() const { return _entry_count; }
299 // find an entry in the hashmap, returns NULL if not found.
300 inline JvmtiTagHashmapEntry* find(oop key) {
301 unsigned int h = hash(key);
302 JvmtiTagHashmapEntry* entry = _table[h];
303 while (entry != NULL) {
304 if (entry->object() == key) {
305 return entry;
306 }
307 entry = entry->next();
308 }
309 return NULL;
310 }
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 }
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 }
334 // if the number of entries exceed the threshold then resize
335 if (entry_count() > resize_threshold() && is_resizing_enabled()) {
336 resize();
337 }
338 }
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 if (key == entry->object()) {
347 break;
348 }
349 prev = entry;
350 entry = entry->next();
351 }
352 if (entry != NULL) {
353 remove(prev, h, entry);
354 }
355 return entry;
356 }
358 // iterate over all entries in the hashmap
359 void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
360 };
362 // possible hashmap sizes - odd primes that roughly double in size.
363 // To avoid excessive resizing the odd primes from 4801-76831 and
364 // 76831-307261 have been removed. The list must be terminated by -1.
365 int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891,
366 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
369 // A supporting class for iterating over all entries in Hashmap
370 class JvmtiTagHashmapEntryClosure {
371 public:
372 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
373 };
376 // iterate over all entries in the hashmap
377 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
378 for (int i=0; i<_size; i++) {
379 JvmtiTagHashmapEntry* entry = _table[i];
380 JvmtiTagHashmapEntry* prev = NULL;
381 while (entry != NULL) {
382 // obtain the next entry before invoking do_entry - this is
383 // necessary because do_entry may remove the entry from the
384 // hashmap.
385 JvmtiTagHashmapEntry* next = entry->next();
386 closure->do_entry(entry);
387 entry = next;
388 }
389 }
390 }
392 // debugging
393 void JvmtiTagHashmap::print_memory_usage() {
394 intptr_t p = (intptr_t)this;
395 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
397 // table + entries in KB
398 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
399 entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
401 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
402 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
403 entry_count(), hashmap_usage, weak_globals_usage);
404 }
406 // compute threshold for the next trace message
407 void JvmtiTagHashmap::compute_next_trace_threshold() {
408 if (trace_threshold() < medium_trace_threshold) {
409 _trace_threshold += small_trace_threshold;
410 } else {
411 if (trace_threshold() < large_trace_threshold) {
412 _trace_threshold += medium_trace_threshold;
413 } else {
414 _trace_threshold += large_trace_threshold;
415 }
416 }
417 }
419 // create a JvmtiTagMap
420 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
421 _env(env),
422 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
423 _free_entries(NULL),
424 _free_entries_count(0)
425 {
426 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
427 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
429 _hashmap = new JvmtiTagHashmap();
431 // finally add us to the environment
432 ((JvmtiEnvBase *)env)->set_tag_map(this);
433 }
436 // destroy a JvmtiTagMap
437 JvmtiTagMap::~JvmtiTagMap() {
439 // no lock acquired as we assume the enclosing environment is
440 // also being destroryed.
441 ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
443 JvmtiTagHashmapEntry** table = _hashmap->table();
444 for (int j = 0; j < _hashmap->size(); j++) {
445 JvmtiTagHashmapEntry* entry = table[j];
446 while (entry != NULL) {
447 JvmtiTagHashmapEntry* next = entry->next();
448 delete entry;
449 entry = next;
450 }
451 }
453 // finally destroy the hashmap
454 delete _hashmap;
455 _hashmap = NULL;
457 // remove any entries on the free list
458 JvmtiTagHashmapEntry* entry = _free_entries;
459 while (entry != NULL) {
460 JvmtiTagHashmapEntry* next = entry->next();
461 delete entry;
462 entry = next;
463 }
464 _free_entries = NULL;
465 }
467 // create a hashmap entry
468 // - if there's an entry on the (per-environment) free list then this
469 // is returned. Otherwise an new entry is allocated.
470 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
471 assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
472 JvmtiTagHashmapEntry* entry;
473 if (_free_entries == NULL) {
474 entry = new JvmtiTagHashmapEntry(ref, tag);
475 } else {
476 assert(_free_entries_count > 0, "mismatched _free_entries_count");
477 _free_entries_count--;
478 entry = _free_entries;
479 _free_entries = entry->next();
480 entry->init(ref, tag);
481 }
482 return entry;
483 }
485 // destroy an entry by returning it to the free list
486 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
487 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
488 // limit the size of the free list
489 if (_free_entries_count >= max_free_entries) {
490 delete entry;
491 } else {
492 entry->set_next(_free_entries);
493 _free_entries = entry;
494 _free_entries_count++;
495 }
496 }
498 // returns the tag map for the given environments. If the tag map
499 // doesn't exist then it is created.
500 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
501 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
502 if (tag_map == NULL) {
503 MutexLocker mu(JvmtiThreadState_lock);
504 tag_map = ((JvmtiEnvBase*)env)->tag_map();
505 if (tag_map == NULL) {
506 tag_map = new JvmtiTagMap(env);
507 }
508 } else {
509 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
510 }
511 return tag_map;
512 }
514 // iterate over all entries in the tag map.
515 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
516 hashmap()->entry_iterate(closure);
517 }
519 // returns true if the hashmaps are empty
520 bool JvmtiTagMap::is_empty() {
521 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
522 return hashmap()->entry_count() == 0;
523 }
526 // Return the tag value for an object, or 0 if the object is
527 // not tagged
528 //
529 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
530 JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
531 if (entry == NULL) {
532 return 0;
533 } else {
534 return entry->tag();
535 }
536 }
539 // A CallbackWrapper is a support class for querying and tagging an object
540 // around a callback to a profiler. The constructor does pre-callback
541 // work to get the tag value, klass tag value, ... and the destructor
542 // does the post-callback work of tagging or untagging the object.
543 //
544 // {
545 // CallbackWrapper wrapper(tag_map, o);
546 //
547 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
548 //
549 // } // wrapper goes out of scope here which results in the destructor
550 // checking to see if the object has been tagged, untagged, or the
551 // tag value has changed.
552 //
553 class CallbackWrapper : public StackObj {
554 private:
555 JvmtiTagMap* _tag_map;
556 JvmtiTagHashmap* _hashmap;
557 JvmtiTagHashmapEntry* _entry;
558 oop _o;
559 jlong _obj_size;
560 jlong _obj_tag;
561 jlong _klass_tag;
563 protected:
564 JvmtiTagMap* tag_map() const { return _tag_map; }
566 // invoked post-callback to tag, untag, or update the tag of an object
567 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
568 JvmtiTagHashmapEntry* entry, jlong obj_tag);
569 public:
570 CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
571 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
572 "MT unsafe or must be VM thread");
574 // object to tag
575 _o = o;
577 // object size
578 _obj_size = (jlong)_o->size() * wordSize;
580 // record the context
581 _tag_map = tag_map;
582 _hashmap = tag_map->hashmap();
583 _entry = _hashmap->find(_o);
585 // get object tag
586 _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
588 // get the class and the class's tag value
589 assert(SystemDictionary::Class_klass()->oop_is_instanceMirror(), "Is not?");
591 _klass_tag = tag_for(tag_map, _o->klass()->java_mirror());
592 }
594 ~CallbackWrapper() {
595 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
596 }
598 inline jlong* obj_tag_p() { return &_obj_tag; }
599 inline jlong obj_size() const { return _obj_size; }
600 inline jlong obj_tag() const { return _obj_tag; }
601 inline jlong klass_tag() const { return _klass_tag; }
602 };
606 // callback post-callback to tag, untag, or update the tag of an object
607 void inline CallbackWrapper::post_callback_tag_update(oop o,
608 JvmtiTagHashmap* hashmap,
609 JvmtiTagHashmapEntry* entry,
610 jlong obj_tag) {
611 if (entry == NULL) {
612 if (obj_tag != 0) {
613 // callback has tagged the object
614 assert(Thread::current()->is_VM_thread(), "must be VMThread");
615 entry = tag_map()->create_entry(o, obj_tag);
616 hashmap->add(o, entry);
617 }
618 } else {
619 // object was previously tagged - the callback may have untagged
620 // the object or changed the tag value
621 if (obj_tag == 0) {
623 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
624 assert(entry_removed == entry, "checking");
625 tag_map()->destroy_entry(entry);
627 } else {
628 if (obj_tag != entry->tag()) {
629 entry->set_tag(obj_tag);
630 }
631 }
632 }
633 }
635 // An extended CallbackWrapper used when reporting an object reference
636 // to the agent.
637 //
638 // {
639 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
640 //
641 // (*callback)(wrapper.klass_tag(),
642 // wrapper.obj_size(),
643 // wrapper.obj_tag_p()
644 // wrapper.referrer_tag_p(), ...)
645 //
646 // } // wrapper goes out of scope here which results in the destructor
647 // checking to see if the referrer object has been tagged, untagged,
648 // or the tag value has changed.
649 //
650 class TwoOopCallbackWrapper : public CallbackWrapper {
651 private:
652 bool _is_reference_to_self;
653 JvmtiTagHashmap* _referrer_hashmap;
654 JvmtiTagHashmapEntry* _referrer_entry;
655 oop _referrer;
656 jlong _referrer_obj_tag;
657 jlong _referrer_klass_tag;
658 jlong* _referrer_tag_p;
660 bool is_reference_to_self() const { return _is_reference_to_self; }
662 public:
663 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
664 CallbackWrapper(tag_map, o)
665 {
666 // self reference needs to be handled in a special way
667 _is_reference_to_self = (referrer == o);
669 if (_is_reference_to_self) {
670 _referrer_klass_tag = klass_tag();
671 _referrer_tag_p = obj_tag_p();
672 } else {
673 _referrer = referrer;
674 // record the context
675 _referrer_hashmap = tag_map->hashmap();
676 _referrer_entry = _referrer_hashmap->find(_referrer);
678 // get object tag
679 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
680 _referrer_tag_p = &_referrer_obj_tag;
682 // get referrer class tag.
683 _referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror());
684 }
685 }
687 ~TwoOopCallbackWrapper() {
688 if (!is_reference_to_self()){
689 post_callback_tag_update(_referrer,
690 _referrer_hashmap,
691 _referrer_entry,
692 _referrer_obj_tag);
693 }
694 }
696 // address of referrer tag
697 // (for a self reference this will return the same thing as obj_tag_p())
698 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
700 // referrer's class tag
701 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
702 };
704 // tag an object
705 //
706 // This function is performance critical. If many threads attempt to tag objects
707 // around the same time then it's possible that the Mutex associated with the
708 // tag map will be a hot lock.
709 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
710 MutexLocker ml(lock());
712 // resolve the object
713 oop o = JNIHandles::resolve_non_null(object);
715 // see if the object is already tagged
716 JvmtiTagHashmap* hashmap = _hashmap;
717 JvmtiTagHashmapEntry* entry = hashmap->find(o);
719 // if the object is not already tagged then we tag it
720 if (entry == NULL) {
721 if (tag != 0) {
722 entry = create_entry(o, tag);
723 hashmap->add(o, entry);
724 } else {
725 // no-op
726 }
727 } else {
728 // if the object is already tagged then we either update
729 // the tag (if a new tag value has been provided)
730 // or remove the object if the new tag value is 0.
731 if (tag == 0) {
732 hashmap->remove(o);
733 destroy_entry(entry);
734 } else {
735 entry->set_tag(tag);
736 }
737 }
738 }
740 // get the tag for an object
741 jlong JvmtiTagMap::get_tag(jobject object) {
742 MutexLocker ml(lock());
744 // resolve the object
745 oop o = JNIHandles::resolve_non_null(object);
747 return tag_for(this, o);
748 }
751 // Helper class used to describe the static or instance fields of a class.
752 // For each field it holds the field index (as defined by the JVMTI specification),
753 // the field type, and the offset.
755 class ClassFieldDescriptor: public CHeapObj<mtInternal> {
756 private:
757 int _field_index;
758 int _field_offset;
759 char _field_type;
760 public:
761 ClassFieldDescriptor(int index, char type, int offset) :
762 _field_index(index), _field_type(type), _field_offset(offset) {
763 }
764 int field_index() const { return _field_index; }
765 char field_type() const { return _field_type; }
766 int field_offset() const { return _field_offset; }
767 };
769 class ClassFieldMap: public CHeapObj<mtInternal> {
770 private:
771 enum {
772 initial_field_count = 5
773 };
775 // list of field descriptors
776 GrowableArray<ClassFieldDescriptor*>* _fields;
778 // constructor
779 ClassFieldMap();
781 // add a field
782 void add(int index, char type, int offset);
784 // returns the field count for the given class
785 static int compute_field_count(instanceKlassHandle ikh);
787 public:
788 ~ClassFieldMap();
790 // access
791 int field_count() { return _fields->length(); }
792 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
794 // functions to create maps of static or instance fields
795 static ClassFieldMap* create_map_of_static_fields(Klass* k);
796 static ClassFieldMap* create_map_of_instance_fields(oop obj);
797 };
799 ClassFieldMap::ClassFieldMap() {
800 _fields = new (ResourceObj::C_HEAP, mtInternal)
801 GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
802 }
804 ClassFieldMap::~ClassFieldMap() {
805 for (int i=0; i<_fields->length(); i++) {
806 delete _fields->at(i);
807 }
808 delete _fields;
809 }
811 void ClassFieldMap::add(int index, char type, int offset) {
812 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
813 _fields->append(field);
814 }
816 // Returns a heap allocated ClassFieldMap to describe the static fields
817 // of the given class.
818 //
819 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
820 HandleMark hm;
821 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
823 // create the field map
824 ClassFieldMap* field_map = new ClassFieldMap();
826 FilteredFieldStream f(ikh, false, false);
827 int max_field_index = f.field_count()-1;
829 int index = 0;
830 for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
831 // ignore instance fields
832 if (!fld.access_flags().is_static()) {
833 continue;
834 }
835 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
836 }
837 return field_map;
838 }
840 // Returns a heap allocated ClassFieldMap to describe the instance fields
841 // of the given class. All instance fields are included (this means public
842 // and private fields declared in superclasses and superinterfaces too).
843 //
844 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
845 HandleMark hm;
846 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
848 // create the field map
849 ClassFieldMap* field_map = new ClassFieldMap();
851 FilteredFieldStream f(ikh, false, false);
853 int max_field_index = f.field_count()-1;
855 int index = 0;
856 for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
857 // ignore static fields
858 if (fld.access_flags().is_static()) {
859 continue;
860 }
861 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
862 }
864 return field_map;
865 }
867 // Helper class used to cache a ClassFileMap for the instance fields of
868 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
869 // heap iteration and avoid creating a field map for each object in the heap
870 // (only need to create the map when the first instance of a class is encountered).
871 //
872 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
873 private:
874 enum {
875 initial_class_count = 200
876 };
877 ClassFieldMap* _field_map;
879 ClassFieldMap* field_map() const { return _field_map; }
881 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
882 ~JvmtiCachedClassFieldMap();
884 static GrowableArray<InstanceKlass*>* _class_list;
885 static void add_to_class_list(InstanceKlass* ik);
887 public:
888 // returns the field map for a given object (returning map cached
889 // by InstanceKlass if possible
890 static ClassFieldMap* get_map_of_instance_fields(oop obj);
892 // removes the field map from all instanceKlasses - should be
893 // called before VM operation completes
894 static void clear_cache();
896 // returns the number of ClassFieldMap cached by instanceKlasses
897 static int cached_field_map_count();
898 };
900 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
902 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
903 _field_map = field_map;
904 }
906 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
907 if (_field_map != NULL) {
908 delete _field_map;
909 }
910 }
912 // Marker class to ensure that the class file map cache is only used in a defined
913 // scope.
914 class ClassFieldMapCacheMark : public StackObj {
915 private:
916 static bool _is_active;
917 public:
918 ClassFieldMapCacheMark() {
919 assert(Thread::current()->is_VM_thread(), "must be VMThread");
920 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
921 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
922 _is_active = true;
923 }
924 ~ClassFieldMapCacheMark() {
925 JvmtiCachedClassFieldMap::clear_cache();
926 _is_active = false;
927 }
928 static bool is_active() { return _is_active; }
929 };
931 bool ClassFieldMapCacheMark::_is_active;
934 // record that the given InstanceKlass is caching a field map
935 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
936 if (_class_list == NULL) {
937 _class_list = new (ResourceObj::C_HEAP, mtInternal)
938 GrowableArray<InstanceKlass*>(initial_class_count, true);
939 }
940 _class_list->push(ik);
941 }
943 // returns the instance field map for the given object
944 // (returns field map cached by the InstanceKlass if possible)
945 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
946 assert(Thread::current()->is_VM_thread(), "must be VMThread");
947 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
949 Klass* k = obj->klass();
950 InstanceKlass* ik = InstanceKlass::cast(k);
952 // return cached map if possible
953 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
954 if (cached_map != NULL) {
955 assert(cached_map->field_map() != NULL, "missing field list");
956 return cached_map->field_map();
957 } else {
958 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
959 cached_map = new JvmtiCachedClassFieldMap(field_map);
960 ik->set_jvmti_cached_class_field_map(cached_map);
961 add_to_class_list(ik);
962 return field_map;
963 }
964 }
966 // remove the fields maps cached from all instanceKlasses
967 void JvmtiCachedClassFieldMap::clear_cache() {
968 assert(Thread::current()->is_VM_thread(), "must be VMThread");
969 if (_class_list != NULL) {
970 for (int i = 0; i < _class_list->length(); i++) {
971 InstanceKlass* ik = _class_list->at(i);
972 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
973 assert(cached_map != NULL, "should not be NULL");
974 ik->set_jvmti_cached_class_field_map(NULL);
975 delete cached_map; // deletes the encapsulated field map
976 }
977 delete _class_list;
978 _class_list = NULL;
979 }
980 }
982 // returns the number of ClassFieldMap cached by instanceKlasses
983 int JvmtiCachedClassFieldMap::cached_field_map_count() {
984 return (_class_list == NULL) ? 0 : _class_list->length();
985 }
987 // helper function to indicate if an object is filtered by its tag or class tag
988 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
989 jlong klass_tag,
990 int heap_filter) {
991 // apply the heap filter
992 if (obj_tag != 0) {
993 // filter out tagged objects
994 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
995 } else {
996 // filter out untagged objects
997 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
998 }
999 if (klass_tag != 0) {
1000 // filter out objects with tagged classes
1001 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1002 } else {
1003 // filter out objects with untagged classes.
1004 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1005 }
1006 return false;
1007 }
1009 // helper function to indicate if an object is filtered by a klass filter
1010 static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
1011 if (!klass_filter.is_null()) {
1012 if (obj->klass() != klass_filter()) {
1013 return true;
1014 }
1015 }
1016 return false;
1017 }
1019 // helper function to tell if a field is a primitive field or not
1020 static inline bool is_primitive_field_type(char type) {
1021 return (type != 'L' && type != '[');
1022 }
1024 // helper function to copy the value from location addr to jvalue.
1025 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1026 switch (value_type) {
1027 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1028 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
1029 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
1030 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
1031 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
1032 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
1033 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
1034 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
1035 default: ShouldNotReachHere();
1036 }
1037 }
1039 // helper function to invoke string primitive value callback
1040 // returns visit control flags
1041 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1042 CallbackWrapper* wrapper,
1043 oop str,
1044 void* user_data)
1045 {
1046 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1048 typeArrayOop s_value = java_lang_String::value(str);
1050 // JDK-6584008: the value field may be null if a String instance is
1051 // partially constructed.
1052 if (s_value == NULL) {
1053 return 0;
1054 }
1055 // get the string value and length
1056 // (string value may be offset from the base)
1057 int s_len = java_lang_String::length(str);
1058 int s_offset = java_lang_String::offset(str);
1059 jchar* value;
1060 if (s_len > 0) {
1061 value = s_value->char_at_addr(s_offset);
1062 } else {
1063 value = (jchar*) s_value->base(T_CHAR);
1064 }
1066 // invoke the callback
1067 return (*cb)(wrapper->klass_tag(),
1068 wrapper->obj_size(),
1069 wrapper->obj_tag_p(),
1070 value,
1071 (jint)s_len,
1072 user_data);
1073 }
1075 // helper function to invoke string primitive value callback
1076 // returns visit control flags
1077 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1078 CallbackWrapper* wrapper,
1079 oop obj,
1080 void* user_data)
1081 {
1082 assert(obj->is_typeArray(), "not a primitive array");
1084 // get base address of first element
1085 typeArrayOop array = typeArrayOop(obj);
1086 BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
1087 void* elements = array->base(type);
1089 // jvmtiPrimitiveType is defined so this mapping is always correct
1090 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1092 return (*cb)(wrapper->klass_tag(),
1093 wrapper->obj_size(),
1094 wrapper->obj_tag_p(),
1095 (jint)array->length(),
1096 elem_type,
1097 elements,
1098 user_data);
1099 }
1101 // helper function to invoke the primitive field callback for all static fields
1102 // of a given class
1103 static jint invoke_primitive_field_callback_for_static_fields
1104 (CallbackWrapper* wrapper,
1105 oop obj,
1106 jvmtiPrimitiveFieldCallback cb,
1107 void* user_data)
1108 {
1109 // for static fields only the index will be set
1110 static jvmtiHeapReferenceInfo reference_info = { 0 };
1112 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1113 if (java_lang_Class::is_primitive(obj)) {
1114 return 0;
1115 }
1116 Klass* klass = java_lang_Class::as_Klass(obj);
1118 // ignore classes for object and type arrays
1119 if (!klass->oop_is_instance()) {
1120 return 0;
1121 }
1123 // ignore classes which aren't linked yet
1124 InstanceKlass* ik = InstanceKlass::cast(klass);
1125 if (!ik->is_linked()) {
1126 return 0;
1127 }
1129 // get the field map
1130 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1132 // invoke the callback for each static primitive field
1133 for (int i=0; i<field_map->field_count(); i++) {
1134 ClassFieldDescriptor* field = field_map->field_at(i);
1136 // ignore non-primitive fields
1137 char type = field->field_type();
1138 if (!is_primitive_field_type(type)) {
1139 continue;
1140 }
1141 // one-to-one mapping
1142 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1144 // get offset and field value
1145 int offset = field->field_offset();
1146 address addr = (address)klass->java_mirror() + offset;
1147 jvalue value;
1148 copy_to_jvalue(&value, addr, value_type);
1150 // field index
1151 reference_info.field.index = field->field_index();
1153 // invoke the callback
1154 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1155 &reference_info,
1156 wrapper->klass_tag(),
1157 wrapper->obj_tag_p(),
1158 value,
1159 value_type,
1160 user_data);
1161 if (res & JVMTI_VISIT_ABORT) {
1162 delete field_map;
1163 return res;
1164 }
1165 }
1167 delete field_map;
1168 return 0;
1169 }
1171 // helper function to invoke the primitive field callback for all instance fields
1172 // of a given object
1173 static jint invoke_primitive_field_callback_for_instance_fields(
1174 CallbackWrapper* wrapper,
1175 oop obj,
1176 jvmtiPrimitiveFieldCallback cb,
1177 void* user_data)
1178 {
1179 // for instance fields only the index will be set
1180 static jvmtiHeapReferenceInfo reference_info = { 0 };
1182 // get the map of the instance fields
1183 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1185 // invoke the callback for each instance primitive field
1186 for (int i=0; i<fields->field_count(); i++) {
1187 ClassFieldDescriptor* field = fields->field_at(i);
1189 // ignore non-primitive fields
1190 char type = field->field_type();
1191 if (!is_primitive_field_type(type)) {
1192 continue;
1193 }
1194 // one-to-one mapping
1195 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1197 // get offset and field value
1198 int offset = field->field_offset();
1199 address addr = (address)obj + offset;
1200 jvalue value;
1201 copy_to_jvalue(&value, addr, value_type);
1203 // field index
1204 reference_info.field.index = field->field_index();
1206 // invoke the callback
1207 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1208 &reference_info,
1209 wrapper->klass_tag(),
1210 wrapper->obj_tag_p(),
1211 value,
1212 value_type,
1213 user_data);
1214 if (res & JVMTI_VISIT_ABORT) {
1215 return res;
1216 }
1217 }
1218 return 0;
1219 }
1222 // VM operation to iterate over all objects in the heap (both reachable
1223 // and unreachable)
1224 class VM_HeapIterateOperation: public VM_Operation {
1225 private:
1226 ObjectClosure* _blk;
1227 public:
1228 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1230 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1231 void doit() {
1232 // allows class files maps to be cached during iteration
1233 ClassFieldMapCacheMark cm;
1235 // make sure that heap is parsable (fills TLABs with filler objects)
1236 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1238 // Verify heap before iteration - if the heap gets corrupted then
1239 // JVMTI's IterateOverHeap will crash.
1240 if (VerifyBeforeIteration) {
1241 Universe::verify();
1242 }
1244 // do the iteration
1245 // If this operation encounters a bad object when using CMS,
1246 // consider using safe_object_iterate() which avoids perm gen
1247 // objects that may contain bad references.
1248 Universe::heap()->object_iterate(_blk);
1249 }
1251 };
1254 // An ObjectClosure used to support the deprecated IterateOverHeap and
1255 // IterateOverInstancesOfClass functions
1256 class IterateOverHeapObjectClosure: public ObjectClosure {
1257 private:
1258 JvmtiTagMap* _tag_map;
1259 KlassHandle _klass;
1260 jvmtiHeapObjectFilter _object_filter;
1261 jvmtiHeapObjectCallback _heap_object_callback;
1262 const void* _user_data;
1264 // accessors
1265 JvmtiTagMap* tag_map() const { return _tag_map; }
1266 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1267 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1268 KlassHandle klass() const { return _klass; }
1269 const void* user_data() const { return _user_data; }
1271 // indicates if iteration has been aborted
1272 bool _iteration_aborted;
1273 bool is_iteration_aborted() const { return _iteration_aborted; }
1274 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1276 public:
1277 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1278 KlassHandle klass,
1279 jvmtiHeapObjectFilter object_filter,
1280 jvmtiHeapObjectCallback heap_object_callback,
1281 const void* user_data) :
1282 _tag_map(tag_map),
1283 _klass(klass),
1284 _object_filter(object_filter),
1285 _heap_object_callback(heap_object_callback),
1286 _user_data(user_data),
1287 _iteration_aborted(false)
1288 {
1289 }
1291 void do_object(oop o);
1292 };
1294 // invoked for each object in the heap
1295 void IterateOverHeapObjectClosure::do_object(oop o) {
1296 // check if iteration has been halted
1297 if (is_iteration_aborted()) return;
1299 // ignore any objects that aren't visible to profiler
1300 if (!ServiceUtil::visible_oop(o)) return;
1302 // instanceof check when filtering by klass
1303 if (!klass().is_null() && !o->is_a(klass()())) {
1304 return;
1305 }
1306 // prepare for the calllback
1307 CallbackWrapper wrapper(tag_map(), o);
1309 // if the object is tagged and we're only interested in untagged objects
1310 // then don't invoke the callback. Similiarly, if the object is untagged
1311 // and we're only interested in tagged objects we skip the callback.
1312 if (wrapper.obj_tag() != 0) {
1313 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1314 } else {
1315 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1316 }
1318 // invoke the agent's callback
1319 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1320 wrapper.obj_size(),
1321 wrapper.obj_tag_p(),
1322 (void*)user_data());
1323 if (control == JVMTI_ITERATION_ABORT) {
1324 set_iteration_aborted(true);
1325 }
1326 }
1328 // An ObjectClosure used to support the IterateThroughHeap function
1329 class IterateThroughHeapObjectClosure: public ObjectClosure {
1330 private:
1331 JvmtiTagMap* _tag_map;
1332 KlassHandle _klass;
1333 int _heap_filter;
1334 const jvmtiHeapCallbacks* _callbacks;
1335 const void* _user_data;
1337 // accessor functions
1338 JvmtiTagMap* tag_map() const { return _tag_map; }
1339 int heap_filter() const { return _heap_filter; }
1340 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1341 KlassHandle klass() const { return _klass; }
1342 const void* user_data() const { return _user_data; }
1344 // indicates if the iteration has been aborted
1345 bool _iteration_aborted;
1346 bool is_iteration_aborted() const { return _iteration_aborted; }
1348 // used to check the visit control flags. If the abort flag is set
1349 // then we set the iteration aborted flag so that the iteration completes
1350 // without processing any further objects
1351 bool check_flags_for_abort(jint flags) {
1352 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1353 if (is_abort) {
1354 _iteration_aborted = true;
1355 }
1356 return is_abort;
1357 }
1359 public:
1360 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1361 KlassHandle klass,
1362 int heap_filter,
1363 const jvmtiHeapCallbacks* heap_callbacks,
1364 const void* user_data) :
1365 _tag_map(tag_map),
1366 _klass(klass),
1367 _heap_filter(heap_filter),
1368 _callbacks(heap_callbacks),
1369 _user_data(user_data),
1370 _iteration_aborted(false)
1371 {
1372 }
1374 void do_object(oop o);
1375 };
1377 // invoked for each object in the heap
1378 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1379 // check if iteration has been halted
1380 if (is_iteration_aborted()) return;
1382 // ignore any objects that aren't visible to profiler
1383 if (!ServiceUtil::visible_oop(obj)) return;
1385 // apply class filter
1386 if (is_filtered_by_klass_filter(obj, klass())) return;
1388 // prepare for callback
1389 CallbackWrapper wrapper(tag_map(), obj);
1391 // check if filtered by the heap filter
1392 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1393 return;
1394 }
1396 // for arrays we need the length, otherwise -1
1397 bool is_array = obj->is_array();
1398 int len = is_array ? arrayOop(obj)->length() : -1;
1400 // invoke the object callback (if callback is provided)
1401 if (callbacks()->heap_iteration_callback != NULL) {
1402 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1403 jint res = (*cb)(wrapper.klass_tag(),
1404 wrapper.obj_size(),
1405 wrapper.obj_tag_p(),
1406 (jint)len,
1407 (void*)user_data());
1408 if (check_flags_for_abort(res)) return;
1409 }
1411 // for objects and classes we report primitive fields if callback provided
1412 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1413 jint res;
1414 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1415 if (obj->klass() == SystemDictionary::Class_klass()) {
1416 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1417 obj,
1418 cb,
1419 (void*)user_data());
1420 } else {
1421 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1422 obj,
1423 cb,
1424 (void*)user_data());
1425 }
1426 if (check_flags_for_abort(res)) return;
1427 }
1429 // string callback
1430 if (!is_array &&
1431 callbacks()->string_primitive_value_callback != NULL &&
1432 obj->klass() == SystemDictionary::String_klass()) {
1433 jint res = invoke_string_value_callback(
1434 callbacks()->string_primitive_value_callback,
1435 &wrapper,
1436 obj,
1437 (void*)user_data() );
1438 if (check_flags_for_abort(res)) return;
1439 }
1441 // array callback
1442 if (is_array &&
1443 callbacks()->array_primitive_value_callback != NULL &&
1444 obj->is_typeArray()) {
1445 jint res = invoke_array_primitive_value_callback(
1446 callbacks()->array_primitive_value_callback,
1447 &wrapper,
1448 obj,
1449 (void*)user_data() );
1450 if (check_flags_for_abort(res)) return;
1451 }
1452 };
1455 // Deprecated function to iterate over all objects in the heap
1456 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1457 KlassHandle klass,
1458 jvmtiHeapObjectCallback heap_object_callback,
1459 const void* user_data)
1460 {
1461 MutexLocker ml(Heap_lock);
1462 IterateOverHeapObjectClosure blk(this,
1463 klass,
1464 object_filter,
1465 heap_object_callback,
1466 user_data);
1467 VM_HeapIterateOperation op(&blk);
1468 VMThread::execute(&op);
1469 }
1472 // Iterates over all objects in the heap
1473 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1474 KlassHandle klass,
1475 const jvmtiHeapCallbacks* callbacks,
1476 const void* user_data)
1477 {
1478 MutexLocker ml(Heap_lock);
1479 IterateThroughHeapObjectClosure blk(this,
1480 klass,
1481 heap_filter,
1482 callbacks,
1483 user_data);
1484 VM_HeapIterateOperation op(&blk);
1485 VMThread::execute(&op);
1486 }
1488 // support class for get_objects_with_tags
1490 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1491 private:
1492 JvmtiEnv* _env;
1493 jlong* _tags;
1494 jint _tag_count;
1496 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1497 GrowableArray<uint64_t>* _tag_results; // collected tags
1499 public:
1500 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1501 _env = env;
1502 _tags = (jlong*)tags;
1503 _tag_count = tag_count;
1504 _object_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<jobject>(1,true);
1505 _tag_results = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<uint64_t>(1,true);
1506 }
1508 ~TagObjectCollector() {
1509 delete _object_results;
1510 delete _tag_results;
1511 }
1513 // for each tagged object check if the tag value matches
1514 // - if it matches then we create a JNI local reference to the object
1515 // and record the reference and tag value.
1516 //
1517 void do_entry(JvmtiTagHashmapEntry* entry) {
1518 for (int i=0; i<_tag_count; i++) {
1519 if (_tags[i] == entry->tag()) {
1520 oop o = entry->object();
1521 assert(o != NULL && Universe::heap()->is_in_reserved(o), "sanity check");
1522 jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1523 _object_results->append(ref);
1524 _tag_results->append((uint64_t)entry->tag());
1525 }
1526 }
1527 }
1529 // return the results from the collection
1530 //
1531 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1532 jvmtiError error;
1533 int count = _object_results->length();
1534 assert(count >= 0, "sanity check");
1536 // if object_result_ptr is not NULL then allocate the result and copy
1537 // in the object references.
1538 if (object_result_ptr != NULL) {
1539 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1540 if (error != JVMTI_ERROR_NONE) {
1541 return error;
1542 }
1543 for (int i=0; i<count; i++) {
1544 (*object_result_ptr)[i] = _object_results->at(i);
1545 }
1546 }
1548 // if tag_result_ptr is not NULL then allocate the result and copy
1549 // in the tag values.
1550 if (tag_result_ptr != NULL) {
1551 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1552 if (error != JVMTI_ERROR_NONE) {
1553 if (object_result_ptr != NULL) {
1554 _env->Deallocate((unsigned char*)object_result_ptr);
1555 }
1556 return error;
1557 }
1558 for (int i=0; i<count; i++) {
1559 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1560 }
1561 }
1563 *count_ptr = count;
1564 return JVMTI_ERROR_NONE;
1565 }
1566 };
1568 // return the list of objects with the specified tags
1569 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1570 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1572 TagObjectCollector collector(env(), tags, count);
1573 {
1574 // iterate over all tagged objects
1575 MutexLocker ml(lock());
1576 entry_iterate(&collector);
1577 }
1578 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1579 }
1582 // ObjectMarker is used to support the marking objects when walking the
1583 // heap.
1584 //
1585 // This implementation uses the existing mark bits in an object for
1586 // marking. Objects that are marked must later have their headers restored.
1587 // As most objects are unlocked and don't have their identity hash computed
1588 // we don't have to save their headers. Instead we save the headers that
1589 // are "interesting". Later when the headers are restored this implementation
1590 // restores all headers to their initial value and then restores the few
1591 // objects that had interesting headers.
1592 //
1593 // Future work: This implementation currently uses growable arrays to save
1594 // the oop and header of interesting objects. As an optimization we could
1595 // use the same technique as the GC and make use of the unused area
1596 // between top() and end().
1597 //
1599 // An ObjectClosure used to restore the mark bits of an object
1600 class RestoreMarksClosure : public ObjectClosure {
1601 public:
1602 void do_object(oop o) {
1603 if (o != NULL) {
1604 markOop mark = o->mark();
1605 if (mark->is_marked()) {
1606 o->init_mark();
1607 }
1608 }
1609 }
1610 };
1612 // ObjectMarker provides the mark and visited functions
1613 class ObjectMarker : AllStatic {
1614 private:
1615 // saved headers
1616 static GrowableArray<oop>* _saved_oop_stack;
1617 static GrowableArray<markOop>* _saved_mark_stack;
1618 static bool _needs_reset; // do we need to reset mark bits?
1620 public:
1621 static void init(); // initialize
1622 static void done(); // clean-up
1624 static inline void mark(oop o); // mark an object
1625 static inline bool visited(oop o); // check if object has been visited
1627 static inline bool needs_reset() { return _needs_reset; }
1628 static inline void set_needs_reset(bool v) { _needs_reset = v; }
1629 };
1631 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1632 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1633 bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default
1635 // initialize ObjectMarker - prepares for object marking
1636 void ObjectMarker::init() {
1637 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1639 // prepare heap for iteration
1640 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1642 // create stacks for interesting headers
1643 _saved_mark_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<markOop>(4000, true);
1644 _saved_oop_stack = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(4000, true);
1646 if (UseBiasedLocking) {
1647 BiasedLocking::preserve_marks();
1648 }
1649 }
1651 // Object marking is done so restore object headers
1652 void ObjectMarker::done() {
1653 // iterate over all objects and restore the mark bits to
1654 // their initial value
1655 RestoreMarksClosure blk;
1656 if (needs_reset()) {
1657 Universe::heap()->object_iterate(&blk);
1658 } else {
1659 // We don't need to reset mark bits on this call, but reset the
1660 // flag to the default for the next call.
1661 set_needs_reset(true);
1662 }
1664 // now restore the interesting headers
1665 for (int i = 0; i < _saved_oop_stack->length(); i++) {
1666 oop o = _saved_oop_stack->at(i);
1667 markOop mark = _saved_mark_stack->at(i);
1668 o->set_mark(mark);
1669 }
1671 if (UseBiasedLocking) {
1672 BiasedLocking::restore_marks();
1673 }
1675 // free the stacks
1676 delete _saved_oop_stack;
1677 delete _saved_mark_stack;
1678 }
1680 // mark an object
1681 inline void ObjectMarker::mark(oop o) {
1682 assert(Universe::heap()->is_in(o), "sanity check");
1683 assert(!o->mark()->is_marked(), "should only mark an object once");
1685 // object's mark word
1686 markOop mark = o->mark();
1688 if (mark->must_be_preserved(o)) {
1689 _saved_mark_stack->push(mark);
1690 _saved_oop_stack->push(o);
1691 }
1693 // mark the object
1694 o->set_mark(markOopDesc::prototype()->set_marked());
1695 }
1697 // return true if object is marked
1698 inline bool ObjectMarker::visited(oop o) {
1699 return o->mark()->is_marked();
1700 }
1702 // Stack allocated class to help ensure that ObjectMarker is used
1703 // correctly. Constructor initializes ObjectMarker, destructor calls
1704 // ObjectMarker's done() function to restore object headers.
1705 class ObjectMarkerController : public StackObj {
1706 public:
1707 ObjectMarkerController() {
1708 ObjectMarker::init();
1709 }
1710 ~ObjectMarkerController() {
1711 ObjectMarker::done();
1712 }
1713 };
1716 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1717 // (not performance critical as only used for roots)
1718 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1719 switch (kind) {
1720 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1721 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1722 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR;
1723 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1724 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1725 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1726 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1727 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1728 }
1729 }
1731 // Base class for all heap walk contexts. The base class maintains a flag
1732 // to indicate if the context is valid or not.
1733 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1734 private:
1735 bool _valid;
1736 public:
1737 HeapWalkContext(bool valid) { _valid = valid; }
1738 void invalidate() { _valid = false; }
1739 bool is_valid() const { return _valid; }
1740 };
1742 // A basic heap walk context for the deprecated heap walking functions.
1743 // The context for a basic heap walk are the callbacks and fields used by
1744 // the referrer caching scheme.
1745 class BasicHeapWalkContext: public HeapWalkContext {
1746 private:
1747 jvmtiHeapRootCallback _heap_root_callback;
1748 jvmtiStackReferenceCallback _stack_ref_callback;
1749 jvmtiObjectReferenceCallback _object_ref_callback;
1751 // used for caching
1752 oop _last_referrer;
1753 jlong _last_referrer_tag;
1755 public:
1756 BasicHeapWalkContext() : HeapWalkContext(false) { }
1758 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1759 jvmtiStackReferenceCallback stack_ref_callback,
1760 jvmtiObjectReferenceCallback object_ref_callback) :
1761 HeapWalkContext(true),
1762 _heap_root_callback(heap_root_callback),
1763 _stack_ref_callback(stack_ref_callback),
1764 _object_ref_callback(object_ref_callback),
1765 _last_referrer(NULL),
1766 _last_referrer_tag(0) {
1767 }
1769 // accessors
1770 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1771 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1772 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1774 oop last_referrer() const { return _last_referrer; }
1775 void set_last_referrer(oop referrer) { _last_referrer = referrer; }
1776 jlong last_referrer_tag() const { return _last_referrer_tag; }
1777 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1778 };
1780 // The advanced heap walk context for the FollowReferences functions.
1781 // The context is the callbacks, and the fields used for filtering.
1782 class AdvancedHeapWalkContext: public HeapWalkContext {
1783 private:
1784 jint _heap_filter;
1785 KlassHandle _klass_filter;
1786 const jvmtiHeapCallbacks* _heap_callbacks;
1788 public:
1789 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1791 AdvancedHeapWalkContext(jint heap_filter,
1792 KlassHandle klass_filter,
1793 const jvmtiHeapCallbacks* heap_callbacks) :
1794 HeapWalkContext(true),
1795 _heap_filter(heap_filter),
1796 _klass_filter(klass_filter),
1797 _heap_callbacks(heap_callbacks) {
1798 }
1800 // accessors
1801 jint heap_filter() const { return _heap_filter; }
1802 KlassHandle klass_filter() const { return _klass_filter; }
1804 const jvmtiHeapReferenceCallback heap_reference_callback() const {
1805 return _heap_callbacks->heap_reference_callback;
1806 };
1807 const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1808 return _heap_callbacks->primitive_field_callback;
1809 }
1810 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1811 return _heap_callbacks->array_primitive_value_callback;
1812 }
1813 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1814 return _heap_callbacks->string_primitive_value_callback;
1815 }
1816 };
1818 // The CallbackInvoker is a class with static functions that the heap walk can call
1819 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1820 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1821 // mode is for the newer FollowReferences function which supports a lot of
1822 // additional callbacks.
1823 class CallbackInvoker : AllStatic {
1824 private:
1825 // heap walk styles
1826 enum { basic, advanced };
1827 static int _heap_walk_type;
1828 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1829 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1831 // context for basic style heap walk
1832 static BasicHeapWalkContext _basic_context;
1833 static BasicHeapWalkContext* basic_context() {
1834 assert(_basic_context.is_valid(), "invalid");
1835 return &_basic_context;
1836 }
1838 // context for advanced style heap walk
1839 static AdvancedHeapWalkContext _advanced_context;
1840 static AdvancedHeapWalkContext* advanced_context() {
1841 assert(_advanced_context.is_valid(), "invalid");
1842 return &_advanced_context;
1843 }
1845 // context needed for all heap walks
1846 static JvmtiTagMap* _tag_map;
1847 static const void* _user_data;
1848 static GrowableArray<oop>* _visit_stack;
1850 // accessors
1851 static JvmtiTagMap* tag_map() { return _tag_map; }
1852 static const void* user_data() { return _user_data; }
1853 static GrowableArray<oop>* visit_stack() { return _visit_stack; }
1855 // if the object hasn't been visited then push it onto the visit stack
1856 // so that it will be visited later
1857 static inline bool check_for_visit(oop obj) {
1858 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1859 return true;
1860 }
1862 // invoke basic style callbacks
1863 static inline bool invoke_basic_heap_root_callback
1864 (jvmtiHeapRootKind root_kind, oop obj);
1865 static inline bool invoke_basic_stack_ref_callback
1866 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1867 int slot, oop obj);
1868 static inline bool invoke_basic_object_reference_callback
1869 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1871 // invoke advanced style callbacks
1872 static inline bool invoke_advanced_heap_root_callback
1873 (jvmtiHeapReferenceKind ref_kind, oop obj);
1874 static inline bool invoke_advanced_stack_ref_callback
1875 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1876 jmethodID method, jlocation bci, jint slot, oop obj);
1877 static inline bool invoke_advanced_object_reference_callback
1878 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1880 // used to report the value of primitive fields
1881 static inline bool report_primitive_field
1882 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1884 public:
1885 // initialize for basic mode
1886 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1887 GrowableArray<oop>* visit_stack,
1888 const void* user_data,
1889 BasicHeapWalkContext context);
1891 // initialize for advanced mode
1892 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1893 GrowableArray<oop>* visit_stack,
1894 const void* user_data,
1895 AdvancedHeapWalkContext context);
1897 // functions to report roots
1898 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
1899 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1900 jmethodID m, oop o);
1901 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1902 jmethodID method, jlocation bci, jint slot, oop o);
1904 // functions to report references
1905 static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
1906 static inline bool report_class_reference(oop referrer, oop referree);
1907 static inline bool report_class_loader_reference(oop referrer, oop referree);
1908 static inline bool report_signers_reference(oop referrer, oop referree);
1909 static inline bool report_protection_domain_reference(oop referrer, oop referree);
1910 static inline bool report_superclass_reference(oop referrer, oop referree);
1911 static inline bool report_interface_reference(oop referrer, oop referree);
1912 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
1913 static inline bool report_field_reference(oop referrer, oop referree, jint slot);
1914 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
1915 static inline bool report_primitive_array_values(oop array);
1916 static inline bool report_string_value(oop str);
1917 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
1918 static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
1919 };
1921 // statics
1922 int CallbackInvoker::_heap_walk_type;
1923 BasicHeapWalkContext CallbackInvoker::_basic_context;
1924 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1925 JvmtiTagMap* CallbackInvoker::_tag_map;
1926 const void* CallbackInvoker::_user_data;
1927 GrowableArray<oop>* CallbackInvoker::_visit_stack;
1929 // initialize for basic heap walk (IterateOverReachableObjects et al)
1930 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1931 GrowableArray<oop>* visit_stack,
1932 const void* user_data,
1933 BasicHeapWalkContext context) {
1934 _tag_map = tag_map;
1935 _visit_stack = visit_stack;
1936 _user_data = user_data;
1937 _basic_context = context;
1938 _advanced_context.invalidate(); // will trigger assertion if used
1939 _heap_walk_type = basic;
1940 }
1942 // initialize for advanced heap walk (FollowReferences)
1943 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1944 GrowableArray<oop>* visit_stack,
1945 const void* user_data,
1946 AdvancedHeapWalkContext context) {
1947 _tag_map = tag_map;
1948 _visit_stack = visit_stack;
1949 _user_data = user_data;
1950 _advanced_context = context;
1951 _basic_context.invalidate(); // will trigger assertion if used
1952 _heap_walk_type = advanced;
1953 }
1956 // invoke basic style heap root callback
1957 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
1958 assert(ServiceUtil::visible_oop(obj), "checking");
1960 // if we heap roots should be reported
1961 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1962 if (cb == NULL) {
1963 return check_for_visit(obj);
1964 }
1966 CallbackWrapper wrapper(tag_map(), obj);
1967 jvmtiIterationControl control = (*cb)(root_kind,
1968 wrapper.klass_tag(),
1969 wrapper.obj_size(),
1970 wrapper.obj_tag_p(),
1971 (void*)user_data());
1972 // push root to visit stack when following references
1973 if (control == JVMTI_ITERATION_CONTINUE &&
1974 basic_context()->object_ref_callback() != NULL) {
1975 visit_stack()->push(obj);
1976 }
1977 return control != JVMTI_ITERATION_ABORT;
1978 }
1980 // invoke basic style stack ref callback
1981 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
1982 jlong thread_tag,
1983 jint depth,
1984 jmethodID method,
1985 jint slot,
1986 oop obj) {
1987 assert(ServiceUtil::visible_oop(obj), "checking");
1989 // if we stack refs should be reported
1990 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
1991 if (cb == NULL) {
1992 return check_for_visit(obj);
1993 }
1995 CallbackWrapper wrapper(tag_map(), obj);
1996 jvmtiIterationControl control = (*cb)(root_kind,
1997 wrapper.klass_tag(),
1998 wrapper.obj_size(),
1999 wrapper.obj_tag_p(),
2000 thread_tag,
2001 depth,
2002 method,
2003 slot,
2004 (void*)user_data());
2005 // push root to visit stack when following references
2006 if (control == JVMTI_ITERATION_CONTINUE &&
2007 basic_context()->object_ref_callback() != NULL) {
2008 visit_stack()->push(obj);
2009 }
2010 return control != JVMTI_ITERATION_ABORT;
2011 }
2013 // invoke basic style object reference callback
2014 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2015 oop referrer,
2016 oop referree,
2017 jint index) {
2019 assert(ServiceUtil::visible_oop(referrer), "checking");
2020 assert(ServiceUtil::visible_oop(referree), "checking");
2022 BasicHeapWalkContext* context = basic_context();
2024 // callback requires the referrer's tag. If it's the same referrer
2025 // as the last call then we use the cached value.
2026 jlong referrer_tag;
2027 if (referrer == context->last_referrer()) {
2028 referrer_tag = context->last_referrer_tag();
2029 } else {
2030 referrer_tag = tag_for(tag_map(), referrer);
2031 }
2033 // do the callback
2034 CallbackWrapper wrapper(tag_map(), referree);
2035 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2036 jvmtiIterationControl control = (*cb)(ref_kind,
2037 wrapper.klass_tag(),
2038 wrapper.obj_size(),
2039 wrapper.obj_tag_p(),
2040 referrer_tag,
2041 index,
2042 (void*)user_data());
2044 // record referrer and referrer tag. For self-references record the
2045 // tag value from the callback as this might differ from referrer_tag.
2046 context->set_last_referrer(referrer);
2047 if (referrer == referree) {
2048 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2049 } else {
2050 context->set_last_referrer_tag(referrer_tag);
2051 }
2053 if (control == JVMTI_ITERATION_CONTINUE) {
2054 return check_for_visit(referree);
2055 } else {
2056 return control != JVMTI_ITERATION_ABORT;
2057 }
2058 }
2060 // invoke advanced style heap root callback
2061 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2062 oop obj) {
2063 assert(ServiceUtil::visible_oop(obj), "checking");
2065 AdvancedHeapWalkContext* context = advanced_context();
2067 // check that callback is provided
2068 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2069 if (cb == NULL) {
2070 return check_for_visit(obj);
2071 }
2073 // apply class filter
2074 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2075 return check_for_visit(obj);
2076 }
2078 // setup the callback wrapper
2079 CallbackWrapper wrapper(tag_map(), obj);
2081 // apply tag filter
2082 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2083 wrapper.klass_tag(),
2084 context->heap_filter())) {
2085 return check_for_visit(obj);
2086 }
2088 // for arrays we need the length, otherwise -1
2089 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2091 // invoke the callback
2092 jint res = (*cb)(ref_kind,
2093 NULL, // referrer info
2094 wrapper.klass_tag(),
2095 0, // referrer_class_tag is 0 for heap root
2096 wrapper.obj_size(),
2097 wrapper.obj_tag_p(),
2098 NULL, // referrer_tag_p
2099 len,
2100 (void*)user_data());
2101 if (res & JVMTI_VISIT_ABORT) {
2102 return false;// referrer class tag
2103 }
2104 if (res & JVMTI_VISIT_OBJECTS) {
2105 check_for_visit(obj);
2106 }
2107 return true;
2108 }
2110 // report a reference from a thread stack to an object
2111 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2112 jlong thread_tag,
2113 jlong tid,
2114 int depth,
2115 jmethodID method,
2116 jlocation bci,
2117 jint slot,
2118 oop obj) {
2119 assert(ServiceUtil::visible_oop(obj), "checking");
2121 AdvancedHeapWalkContext* context = advanced_context();
2123 // check that callback is provider
2124 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2125 if (cb == NULL) {
2126 return check_for_visit(obj);
2127 }
2129 // apply class filter
2130 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2131 return check_for_visit(obj);
2132 }
2134 // setup the callback wrapper
2135 CallbackWrapper wrapper(tag_map(), obj);
2137 // apply tag filter
2138 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2139 wrapper.klass_tag(),
2140 context->heap_filter())) {
2141 return check_for_visit(obj);
2142 }
2144 // setup the referrer info
2145 jvmtiHeapReferenceInfo reference_info;
2146 reference_info.stack_local.thread_tag = thread_tag;
2147 reference_info.stack_local.thread_id = tid;
2148 reference_info.stack_local.depth = depth;
2149 reference_info.stack_local.method = method;
2150 reference_info.stack_local.location = bci;
2151 reference_info.stack_local.slot = slot;
2153 // for arrays we need the length, otherwise -1
2154 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2156 // call into the agent
2157 int res = (*cb)(ref_kind,
2158 &reference_info,
2159 wrapper.klass_tag(),
2160 0, // referrer_class_tag is 0 for heap root (stack)
2161 wrapper.obj_size(),
2162 wrapper.obj_tag_p(),
2163 NULL, // referrer_tag is 0 for root
2164 len,
2165 (void*)user_data());
2167 if (res & JVMTI_VISIT_ABORT) {
2168 return false;
2169 }
2170 if (res & JVMTI_VISIT_OBJECTS) {
2171 check_for_visit(obj);
2172 }
2173 return true;
2174 }
2176 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2177 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2178 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2179 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2180 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2181 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2182 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2183 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2185 // invoke the object reference callback to report a reference
2186 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2187 oop referrer,
2188 oop obj,
2189 jint index)
2190 {
2191 // field index is only valid field in reference_info
2192 static jvmtiHeapReferenceInfo reference_info = { 0 };
2194 assert(ServiceUtil::visible_oop(referrer), "checking");
2195 assert(ServiceUtil::visible_oop(obj), "checking");
2197 AdvancedHeapWalkContext* context = advanced_context();
2199 // check that callback is provider
2200 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2201 if (cb == NULL) {
2202 return check_for_visit(obj);
2203 }
2205 // apply class filter
2206 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2207 return check_for_visit(obj);
2208 }
2210 // setup the callback wrapper
2211 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2213 // apply tag filter
2214 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2215 wrapper.klass_tag(),
2216 context->heap_filter())) {
2217 return check_for_visit(obj);
2218 }
2220 // field index is only valid field in reference_info
2221 reference_info.field.index = index;
2223 // for arrays we need the length, otherwise -1
2224 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2226 // invoke the callback
2227 int res = (*cb)(ref_kind,
2228 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2229 wrapper.klass_tag(),
2230 wrapper.referrer_klass_tag(),
2231 wrapper.obj_size(),
2232 wrapper.obj_tag_p(),
2233 wrapper.referrer_tag_p(),
2234 len,
2235 (void*)user_data());
2237 if (res & JVMTI_VISIT_ABORT) {
2238 return false;
2239 }
2240 if (res & JVMTI_VISIT_OBJECTS) {
2241 check_for_visit(obj);
2242 }
2243 return true;
2244 }
2246 // report a "simple root"
2247 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2248 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2249 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2250 assert(ServiceUtil::visible_oop(obj), "checking");
2252 if (is_basic_heap_walk()) {
2253 // map to old style root kind
2254 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2255 return invoke_basic_heap_root_callback(root_kind, obj);
2256 } else {
2257 assert(is_advanced_heap_walk(), "wrong heap walk type");
2258 return invoke_advanced_heap_root_callback(kind, obj);
2259 }
2260 }
2263 // invoke the primitive array values
2264 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2265 assert(obj->is_typeArray(), "not a primitive array");
2267 AdvancedHeapWalkContext* context = advanced_context();
2268 assert(context->array_primitive_value_callback() != NULL, "no callback");
2270 // apply class filter
2271 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2272 return true;
2273 }
2275 CallbackWrapper wrapper(tag_map(), obj);
2277 // apply tag filter
2278 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2279 wrapper.klass_tag(),
2280 context->heap_filter())) {
2281 return true;
2282 }
2284 // invoke the callback
2285 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2286 &wrapper,
2287 obj,
2288 (void*)user_data());
2289 return (!(res & JVMTI_VISIT_ABORT));
2290 }
2292 // invoke the string value callback
2293 inline bool CallbackInvoker::report_string_value(oop str) {
2294 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2296 AdvancedHeapWalkContext* context = advanced_context();
2297 assert(context->string_primitive_value_callback() != NULL, "no callback");
2299 // apply class filter
2300 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2301 return true;
2302 }
2304 CallbackWrapper wrapper(tag_map(), str);
2306 // apply tag filter
2307 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2308 wrapper.klass_tag(),
2309 context->heap_filter())) {
2310 return true;
2311 }
2313 // invoke the callback
2314 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2315 &wrapper,
2316 str,
2317 (void*)user_data());
2318 return (!(res & JVMTI_VISIT_ABORT));
2319 }
2321 // invoke the primitive field callback
2322 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2323 oop obj,
2324 jint index,
2325 address addr,
2326 char type)
2327 {
2328 // for primitive fields only the index will be set
2329 static jvmtiHeapReferenceInfo reference_info = { 0 };
2331 AdvancedHeapWalkContext* context = advanced_context();
2332 assert(context->primitive_field_callback() != NULL, "no callback");
2334 // apply class filter
2335 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2336 return true;
2337 }
2339 CallbackWrapper wrapper(tag_map(), obj);
2341 // apply tag filter
2342 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2343 wrapper.klass_tag(),
2344 context->heap_filter())) {
2345 return true;
2346 }
2348 // the field index in the referrer
2349 reference_info.field.index = index;
2351 // map the type
2352 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2354 // setup the jvalue
2355 jvalue value;
2356 copy_to_jvalue(&value, addr, value_type);
2358 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2359 int res = (*cb)(ref_kind,
2360 &reference_info,
2361 wrapper.klass_tag(),
2362 wrapper.obj_tag_p(),
2363 value,
2364 value_type,
2365 (void*)user_data());
2366 return (!(res & JVMTI_VISIT_ABORT));
2367 }
2370 // instance field
2371 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2372 jint index,
2373 address value,
2374 char type) {
2375 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2376 obj,
2377 index,
2378 value,
2379 type);
2380 }
2382 // static field
2383 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2384 jint index,
2385 address value,
2386 char type) {
2387 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2388 obj,
2389 index,
2390 value,
2391 type);
2392 }
2394 // report a JNI local (root object) to the profiler
2395 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2396 if (is_basic_heap_walk()) {
2397 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2398 thread_tag,
2399 depth,
2400 m,
2401 -1,
2402 obj);
2403 } else {
2404 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2405 thread_tag, tid,
2406 depth,
2407 m,
2408 (jlocation)-1,
2409 -1,
2410 obj);
2411 }
2412 }
2415 // report a local (stack reference, root object)
2416 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2417 jlong tid,
2418 jint depth,
2419 jmethodID method,
2420 jlocation bci,
2421 jint slot,
2422 oop obj) {
2423 if (is_basic_heap_walk()) {
2424 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2425 thread_tag,
2426 depth,
2427 method,
2428 slot,
2429 obj);
2430 } else {
2431 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2432 thread_tag,
2433 tid,
2434 depth,
2435 method,
2436 bci,
2437 slot,
2438 obj);
2439 }
2440 }
2442 // report an object referencing a class.
2443 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2444 if (is_basic_heap_walk()) {
2445 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2446 } else {
2447 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2448 }
2449 }
2451 // report a class referencing its class loader.
2452 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2453 if (is_basic_heap_walk()) {
2454 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2455 } else {
2456 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2457 }
2458 }
2460 // report a class referencing its signers.
2461 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2462 if (is_basic_heap_walk()) {
2463 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2464 } else {
2465 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2466 }
2467 }
2469 // report a class referencing its protection domain..
2470 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2471 if (is_basic_heap_walk()) {
2472 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2473 } else {
2474 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2475 }
2476 }
2478 // report a class referencing its superclass.
2479 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2480 if (is_basic_heap_walk()) {
2481 // Send this to be consistent with past implementation
2482 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2483 } else {
2484 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2485 }
2486 }
2488 // report a class referencing one of its interfaces.
2489 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2490 if (is_basic_heap_walk()) {
2491 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2492 } else {
2493 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2494 }
2495 }
2497 // report a class referencing one of its static fields.
2498 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2499 if (is_basic_heap_walk()) {
2500 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2501 } else {
2502 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2503 }
2504 }
2506 // report an array referencing an element object
2507 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2508 if (is_basic_heap_walk()) {
2509 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2510 } else {
2511 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2512 }
2513 }
2515 // report an object referencing an instance field object
2516 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2517 if (is_basic_heap_walk()) {
2518 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2519 } else {
2520 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2521 }
2522 }
2524 // report an array referencing an element object
2525 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2526 if (is_basic_heap_walk()) {
2527 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2528 } else {
2529 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2530 }
2531 }
2533 // A supporting closure used to process simple roots
2534 class SimpleRootsClosure : public OopClosure {
2535 private:
2536 jvmtiHeapReferenceKind _kind;
2537 bool _continue;
2539 jvmtiHeapReferenceKind root_kind() { return _kind; }
2541 public:
2542 void set_kind(jvmtiHeapReferenceKind kind) {
2543 _kind = kind;
2544 _continue = true;
2545 }
2547 inline bool stopped() {
2548 return !_continue;
2549 }
2551 void do_oop(oop* obj_p) {
2552 // iteration has terminated
2553 if (stopped()) {
2554 return;
2555 }
2557 // ignore null or deleted handles
2558 oop o = *obj_p;
2559 if (o == NULL || o == JNIHandles::deleted_handle()) {
2560 return;
2561 }
2563 assert(Universe::heap()->is_in_reserved(o), "should be impossible");
2565 jvmtiHeapReferenceKind kind = root_kind();
2566 if (kind == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2567 // SystemDictionary::always_strong_oops_do reports the application
2568 // class loader as a root. We want this root to be reported as
2569 // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2570 if (!o->is_instanceMirror()) {
2571 kind = JVMTI_HEAP_REFERENCE_OTHER;
2572 }
2573 }
2575 // some objects are ignored - in the case of simple
2576 // roots it's mostly Symbol*s that we are skipping
2577 // here.
2578 if (!ServiceUtil::visible_oop(o)) {
2579 return;
2580 }
2582 // invoke the callback
2583 _continue = CallbackInvoker::report_simple_root(kind, o);
2585 }
2586 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2587 };
2589 // A supporting closure used to process JNI locals
2590 class JNILocalRootsClosure : public OopClosure {
2591 private:
2592 jlong _thread_tag;
2593 jlong _tid;
2594 jint _depth;
2595 jmethodID _method;
2596 bool _continue;
2597 public:
2598 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2599 _thread_tag = thread_tag;
2600 _tid = tid;
2601 _depth = depth;
2602 _method = method;
2603 _continue = true;
2604 }
2606 inline bool stopped() {
2607 return !_continue;
2608 }
2610 void do_oop(oop* obj_p) {
2611 // iteration has terminated
2612 if (stopped()) {
2613 return;
2614 }
2616 // ignore null or deleted handles
2617 oop o = *obj_p;
2618 if (o == NULL || o == JNIHandles::deleted_handle()) {
2619 return;
2620 }
2622 if (!ServiceUtil::visible_oop(o)) {
2623 return;
2624 }
2626 // invoke the callback
2627 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2628 }
2629 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2630 };
2633 // A VM operation to iterate over objects that are reachable from
2634 // a set of roots or an initial object.
2635 //
2636 // For VM_HeapWalkOperation the set of roots used is :-
2637 //
2638 // - All JNI global references
2639 // - All inflated monitors
2640 // - All classes loaded by the boot class loader (or all classes
2641 // in the event that class unloading is disabled)
2642 // - All java threads
2643 // - For each java thread then all locals and JNI local references
2644 // on the thread's execution stack
2645 // - All visible/explainable objects from Universes::oops_do
2646 //
2647 class VM_HeapWalkOperation: public VM_Operation {
2648 private:
2649 enum {
2650 initial_visit_stack_size = 4000
2651 };
2653 bool _is_advanced_heap_walk; // indicates FollowReferences
2654 JvmtiTagMap* _tag_map;
2655 Handle _initial_object;
2656 GrowableArray<oop>* _visit_stack; // the visit stack
2658 bool _collecting_heap_roots; // are we collecting roots
2659 bool _following_object_refs; // are we following object references
2661 bool _reporting_primitive_fields; // optional reporting
2662 bool _reporting_primitive_array_values;
2663 bool _reporting_string_values;
2665 GrowableArray<oop>* create_visit_stack() {
2666 return new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(initial_visit_stack_size, true);
2667 }
2669 // accessors
2670 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2671 JvmtiTagMap* tag_map() const { return _tag_map; }
2672 Handle initial_object() const { return _initial_object; }
2674 bool is_following_references() const { return _following_object_refs; }
2676 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2677 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2678 bool is_reporting_string_values() const { return _reporting_string_values; }
2680 GrowableArray<oop>* visit_stack() const { return _visit_stack; }
2682 // iterate over the various object types
2683 inline bool iterate_over_array(oop o);
2684 inline bool iterate_over_type_array(oop o);
2685 inline bool iterate_over_class(oop o);
2686 inline bool iterate_over_object(oop o);
2688 // root collection
2689 inline bool collect_simple_roots();
2690 inline bool collect_stack_roots();
2691 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2693 // visit an object
2694 inline bool visit(oop o);
2696 public:
2697 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2698 Handle initial_object,
2699 BasicHeapWalkContext callbacks,
2700 const void* user_data);
2702 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2703 Handle initial_object,
2704 AdvancedHeapWalkContext callbacks,
2705 const void* user_data);
2707 ~VM_HeapWalkOperation();
2709 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2710 void doit();
2711 };
2714 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2715 Handle initial_object,
2716 BasicHeapWalkContext callbacks,
2717 const void* user_data) {
2718 _is_advanced_heap_walk = false;
2719 _tag_map = tag_map;
2720 _initial_object = initial_object;
2721 _following_object_refs = (callbacks.object_ref_callback() != NULL);
2722 _reporting_primitive_fields = false;
2723 _reporting_primitive_array_values = false;
2724 _reporting_string_values = false;
2725 _visit_stack = create_visit_stack();
2728 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2729 }
2731 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2732 Handle initial_object,
2733 AdvancedHeapWalkContext callbacks,
2734 const void* user_data) {
2735 _is_advanced_heap_walk = true;
2736 _tag_map = tag_map;
2737 _initial_object = initial_object;
2738 _following_object_refs = true;
2739 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2740 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2741 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2742 _visit_stack = create_visit_stack();
2744 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2745 }
2747 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2748 if (_following_object_refs) {
2749 assert(_visit_stack != NULL, "checking");
2750 delete _visit_stack;
2751 _visit_stack = NULL;
2752 }
2753 }
2755 // an array references its class and has a reference to
2756 // each element in the array
2757 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2758 objArrayOop array = objArrayOop(o);
2760 // array reference to its class
2761 oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
2762 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2763 return false;
2764 }
2766 // iterate over the array and report each reference to a
2767 // non-null element
2768 for (int index=0; index<array->length(); index++) {
2769 oop elem = array->obj_at(index);
2770 if (elem == NULL) {
2771 continue;
2772 }
2774 // report the array reference o[index] = elem
2775 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2776 return false;
2777 }
2778 }
2779 return true;
2780 }
2782 // a type array references its class
2783 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2784 Klass* k = o->klass();
2785 oop mirror = k->java_mirror();
2786 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2787 return false;
2788 }
2790 // report the array contents if required
2791 if (is_reporting_primitive_array_values()) {
2792 if (!CallbackInvoker::report_primitive_array_values(o)) {
2793 return false;
2794 }
2795 }
2796 return true;
2797 }
2799 // verify that a static oop field is in range
2800 static inline bool verify_static_oop(InstanceKlass* ik,
2801 oop mirror, int offset) {
2802 address obj_p = (address)mirror + offset;
2803 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2804 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2805 assert(end >= start, "sanity check");
2807 if (obj_p >= start && obj_p < end) {
2808 return true;
2809 } else {
2810 return false;
2811 }
2812 }
2814 // a class references its super class, interfaces, class loader, ...
2815 // and finally its static fields
2816 inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) {
2817 int i;
2818 Klass* klass = java_lang_Class::as_Klass(java_class);
2820 if (klass->oop_is_instance()) {
2821 InstanceKlass* ik = InstanceKlass::cast(klass);
2823 // ignore the class if it's has been initialized yet
2824 if (!ik->is_linked()) {
2825 return true;
2826 }
2828 // get the java mirror
2829 oop mirror = klass->java_mirror();
2831 // super (only if something more interesting than java.lang.Object)
2832 Klass* java_super = ik->java_super();
2833 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2834 oop super = java_super->java_mirror();
2835 if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2836 return false;
2837 }
2838 }
2840 // class loader
2841 oop cl = ik->class_loader();
2842 if (cl != NULL) {
2843 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2844 return false;
2845 }
2846 }
2848 // protection domain
2849 oop pd = ik->protection_domain();
2850 if (pd != NULL) {
2851 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2852 return false;
2853 }
2854 }
2856 // signers
2857 oop signers = ik->signers();
2858 if (signers != NULL) {
2859 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2860 return false;
2861 }
2862 }
2864 // references from the constant pool
2865 {
2866 ConstantPool* pool = ik->constants();
2867 for (int i = 1; i < pool->length(); i++) {
2868 constantTag tag = pool->tag_at(i).value();
2869 if (tag.is_string() || tag.is_klass()) {
2870 oop entry;
2871 if (tag.is_string()) {
2872 entry = pool->resolved_string_at(i);
2873 // If the entry is non-null it is resolved.
2874 if (entry == NULL) continue;
2875 } else {
2876 entry = pool->resolved_klass_at(i)->java_mirror();
2877 }
2878 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2879 return false;
2880 }
2881 }
2882 }
2883 }
2885 // interfaces
2886 // (These will already have been reported as references from the constant pool
2887 // but are specified by IterateOverReachableObjects and must be reported).
2888 Array<Klass*>* interfaces = ik->local_interfaces();
2889 for (i = 0; i < interfaces->length(); i++) {
2890 oop interf = ((Klass*)interfaces->at(i))->java_mirror();
2891 if (interf == NULL) {
2892 continue;
2893 }
2894 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
2895 return false;
2896 }
2897 }
2899 // iterate over the static fields
2901 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
2902 for (i=0; i<field_map->field_count(); i++) {
2903 ClassFieldDescriptor* field = field_map->field_at(i);
2904 char type = field->field_type();
2905 if (!is_primitive_field_type(type)) {
2906 oop fld_o = mirror->obj_field(field->field_offset());
2907 assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check");
2908 if (fld_o != NULL) {
2909 int slot = field->field_index();
2910 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
2911 delete field_map;
2912 return false;
2913 }
2914 }
2915 } else {
2916 if (is_reporting_primitive_fields()) {
2917 address addr = (address)mirror + field->field_offset();
2918 int slot = field->field_index();
2919 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
2920 delete field_map;
2921 return false;
2922 }
2923 }
2924 }
2925 }
2926 delete field_map;
2928 return true;
2929 }
2931 return true;
2932 }
2934 // an object references a class and its instance fields
2935 // (static fields are ignored here as we report these as
2936 // references from the class).
2937 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
2938 // reference to the class
2939 if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) {
2940 return false;
2941 }
2943 // iterate over instance fields
2944 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
2945 for (int i=0; i<field_map->field_count(); i++) {
2946 ClassFieldDescriptor* field = field_map->field_at(i);
2947 char type = field->field_type();
2948 if (!is_primitive_field_type(type)) {
2949 oop fld_o = o->obj_field(field->field_offset());
2950 // ignore any objects that aren't visible to profiler
2951 if (fld_o != NULL && ServiceUtil::visible_oop(fld_o)) {
2952 assert(Universe::heap()->is_in_reserved(fld_o), "unsafe code should not "
2953 "have references to Klass* anymore");
2954 int slot = field->field_index();
2955 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
2956 return false;
2957 }
2958 }
2959 } else {
2960 if (is_reporting_primitive_fields()) {
2961 // primitive instance field
2962 address addr = (address)o + field->field_offset();
2963 int slot = field->field_index();
2964 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
2965 return false;
2966 }
2967 }
2968 }
2969 }
2971 // if the object is a java.lang.String
2972 if (is_reporting_string_values() &&
2973 o->klass() == SystemDictionary::String_klass()) {
2974 if (!CallbackInvoker::report_string_value(o)) {
2975 return false;
2976 }
2977 }
2978 return true;
2979 }
2982 // Collects all simple (non-stack) roots except for threads;
2983 // threads are handled in collect_stack_roots() as an optimization.
2984 // if there's a heap root callback provided then the callback is
2985 // invoked for each simple root.
2986 // if an object reference callback is provided then all simple
2987 // roots are pushed onto the marking stack so that they can be
2988 // processed later
2989 //
2990 inline bool VM_HeapWalkOperation::collect_simple_roots() {
2991 SimpleRootsClosure blk;
2993 // JNI globals
2994 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
2995 JNIHandles::oops_do(&blk);
2996 if (blk.stopped()) {
2997 return false;
2998 }
3000 // Preloaded classes and loader from the system dictionary
3001 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3002 SystemDictionary::always_strong_oops_do(&blk);
3003 KlassToOopClosure klass_blk(&blk);
3004 ClassLoaderDataGraph::always_strong_oops_do(&blk, &klass_blk, false);
3005 if (blk.stopped()) {
3006 return false;
3007 }
3009 // Inflated monitors
3010 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3011 ObjectSynchronizer::oops_do(&blk);
3012 if (blk.stopped()) {
3013 return false;
3014 }
3016 // threads are now handled in collect_stack_roots()
3018 // Other kinds of roots maintained by HotSpot
3019 // Many of these won't be visible but others (such as instances of important
3020 // exceptions) will be visible.
3021 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3022 Universe::oops_do(&blk);
3024 // If there are any non-perm roots in the code cache, visit them.
3025 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3026 CodeBlobToOopClosure look_in_blobs(&blk, !CodeBlobToOopClosure::FixRelocations);
3027 CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3029 return true;
3030 }
3032 // Walk the stack of a given thread and find all references (locals
3033 // and JNI calls) and report these as stack references
3034 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3035 JNILocalRootsClosure* blk)
3036 {
3037 oop threadObj = java_thread->threadObj();
3038 assert(threadObj != NULL, "sanity check");
3040 // only need to get the thread's tag once per thread
3041 jlong thread_tag = tag_for(_tag_map, threadObj);
3043 // also need the thread id
3044 jlong tid = java_lang_Thread::thread_id(threadObj);
3047 if (java_thread->has_last_Java_frame()) {
3049 // vframes are resource allocated
3050 Thread* current_thread = Thread::current();
3051 ResourceMark rm(current_thread);
3052 HandleMark hm(current_thread);
3054 RegisterMap reg_map(java_thread);
3055 frame f = java_thread->last_frame();
3056 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3058 bool is_top_frame = true;
3059 int depth = 0;
3060 frame* last_entry_frame = NULL;
3062 while (vf != NULL) {
3063 if (vf->is_java_frame()) {
3065 // java frame (interpreted, compiled, ...)
3066 javaVFrame *jvf = javaVFrame::cast(vf);
3068 // the jmethodID
3069 jmethodID method = jvf->method()->jmethod_id();
3071 if (!(jvf->method()->is_native())) {
3072 jlocation bci = (jlocation)jvf->bci();
3073 StackValueCollection* locals = jvf->locals();
3074 for (int slot=0; slot<locals->size(); slot++) {
3075 if (locals->at(slot)->type() == T_OBJECT) {
3076 oop o = locals->obj_at(slot)();
3077 if (o == NULL) {
3078 continue;
3079 }
3081 // stack reference
3082 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3083 bci, slot, o)) {
3084 return false;
3085 }
3086 }
3087 }
3088 } else {
3089 blk->set_context(thread_tag, tid, depth, method);
3090 if (is_top_frame) {
3091 // JNI locals for the top frame.
3092 java_thread->active_handles()->oops_do(blk);
3093 } else {
3094 if (last_entry_frame != NULL) {
3095 // JNI locals for the entry frame
3096 assert(last_entry_frame->is_entry_frame(), "checking");
3097 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3098 }
3099 }
3100 }
3101 last_entry_frame = NULL;
3102 depth++;
3103 } else {
3104 // externalVFrame - for an entry frame then we report the JNI locals
3105 // when we find the corresponding javaVFrame
3106 frame* fr = vf->frame_pointer();
3107 assert(fr != NULL, "sanity check");
3108 if (fr->is_entry_frame()) {
3109 last_entry_frame = fr;
3110 }
3111 }
3113 vf = vf->sender();
3114 is_top_frame = false;
3115 }
3116 } else {
3117 // no last java frame but there may be JNI locals
3118 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3119 java_thread->active_handles()->oops_do(blk);
3120 }
3121 return true;
3122 }
3125 // Collects the simple roots for all threads and collects all
3126 // stack roots - for each thread it walks the execution
3127 // stack to find all references and local JNI refs.
3128 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3129 JNILocalRootsClosure blk;
3130 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3131 oop threadObj = thread->threadObj();
3132 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3133 // Collect the simple root for this thread before we
3134 // collect its stack roots
3135 if (!CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD,
3136 threadObj)) {
3137 return false;
3138 }
3139 if (!collect_stack_roots(thread, &blk)) {
3140 return false;
3141 }
3142 }
3143 }
3144 return true;
3145 }
3147 // visit an object
3148 // first mark the object as visited
3149 // second get all the outbound references from this object (in other words, all
3150 // the objects referenced by this object).
3151 //
3152 bool VM_HeapWalkOperation::visit(oop o) {
3153 // mark object as visited
3154 assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3155 ObjectMarker::mark(o);
3157 // instance
3158 if (o->is_instance()) {
3159 if (o->klass() == SystemDictionary::Class_klass()) {
3160 if (!java_lang_Class::is_primitive(o)) {
3161 // a java.lang.Class
3162 return iterate_over_class(o);
3163 }
3164 } else {
3165 return iterate_over_object(o);
3166 }
3167 }
3169 // object array
3170 if (o->is_objArray()) {
3171 return iterate_over_array(o);
3172 }
3174 // type array
3175 if (o->is_typeArray()) {
3176 return iterate_over_type_array(o);
3177 }
3179 return true;
3180 }
3182 void VM_HeapWalkOperation::doit() {
3183 ResourceMark rm;
3184 ObjectMarkerController marker;
3185 ClassFieldMapCacheMark cm;
3187 assert(visit_stack()->is_empty(), "visit stack must be empty");
3189 // the heap walk starts with an initial object or the heap roots
3190 if (initial_object().is_null()) {
3191 // If either collect_stack_roots() or collect_simple_roots()
3192 // returns false at this point, then there are no mark bits
3193 // to reset.
3194 ObjectMarker::set_needs_reset(false);
3196 // Calling collect_stack_roots() before collect_simple_roots()
3197 // can result in a big performance boost for an agent that is
3198 // focused on analyzing references in the thread stacks.
3199 if (!collect_stack_roots()) return;
3201 if (!collect_simple_roots()) return;
3203 // no early return so enable heap traversal to reset the mark bits
3204 ObjectMarker::set_needs_reset(true);
3205 } else {
3206 visit_stack()->push(initial_object()());
3207 }
3209 // object references required
3210 if (is_following_references()) {
3212 // visit each object until all reachable objects have been
3213 // visited or the callback asked to terminate the iteration.
3214 while (!visit_stack()->is_empty()) {
3215 oop o = visit_stack()->pop();
3216 if (!ObjectMarker::visited(o)) {
3217 if (!visit(o)) {
3218 break;
3219 }
3220 }
3221 }
3222 }
3223 }
3225 // iterate over all objects that are reachable from a set of roots
3226 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3227 jvmtiStackReferenceCallback stack_ref_callback,
3228 jvmtiObjectReferenceCallback object_ref_callback,
3229 const void* user_data) {
3230 MutexLocker ml(Heap_lock);
3231 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3232 VM_HeapWalkOperation op(this, Handle(), context, user_data);
3233 VMThread::execute(&op);
3234 }
3236 // iterate over all objects that are reachable from a given object
3237 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3238 jvmtiObjectReferenceCallback object_ref_callback,
3239 const void* user_data) {
3240 oop obj = JNIHandles::resolve(object);
3241 Handle initial_object(Thread::current(), obj);
3243 MutexLocker ml(Heap_lock);
3244 BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3245 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3246 VMThread::execute(&op);
3247 }
3249 // follow references from an initial object or the GC roots
3250 void JvmtiTagMap::follow_references(jint heap_filter,
3251 KlassHandle klass,
3252 jobject object,
3253 const jvmtiHeapCallbacks* callbacks,
3254 const void* user_data)
3255 {
3256 oop obj = JNIHandles::resolve(object);
3257 Handle initial_object(Thread::current(), obj);
3259 MutexLocker ml(Heap_lock);
3260 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3261 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3262 VMThread::execute(&op);
3263 }
3266 void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
3267 // No locks during VM bring-up (0 threads) and no safepoints after main
3268 // thread creation and before VMThread creation (1 thread); initial GC
3269 // verification can happen in that window which gets to here.
3270 assert(Threads::number_of_threads() <= 1 ||
3271 SafepointSynchronize::is_at_safepoint(),
3272 "must be executed at a safepoint");
3273 if (JvmtiEnv::environments_might_exist()) {
3274 JvmtiEnvIterator it;
3275 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3276 JvmtiTagMap* tag_map = env->tag_map();
3277 if (tag_map != NULL && !tag_map->is_empty()) {
3278 tag_map->do_weak_oops(is_alive, f);
3279 }
3280 }
3281 }
3282 }
3284 void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
3286 // does this environment have the OBJECT_FREE event enabled
3287 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3289 // counters used for trace message
3290 int freed = 0;
3291 int moved = 0;
3293 JvmtiTagHashmap* hashmap = this->hashmap();
3295 // reenable sizing (if disabled)
3296 hashmap->set_resizing_enabled(true);
3298 // if the hashmap is empty then we can skip it
3299 if (hashmap->_entry_count == 0) {
3300 return;
3301 }
3303 // now iterate through each entry in the table
3305 JvmtiTagHashmapEntry** table = hashmap->table();
3306 int size = hashmap->size();
3308 JvmtiTagHashmapEntry* delayed_add = NULL;
3310 for (int pos = 0; pos < size; ++pos) {
3311 JvmtiTagHashmapEntry* entry = table[pos];
3312 JvmtiTagHashmapEntry* prev = NULL;
3314 while (entry != NULL) {
3315 JvmtiTagHashmapEntry* next = entry->next();
3317 oop* obj = entry->object_addr();
3319 // has object been GC'ed
3320 if (!is_alive->do_object_b(entry->object())) {
3321 // grab the tag
3322 jlong tag = entry->tag();
3323 guarantee(tag != 0, "checking");
3325 // remove GC'ed entry from hashmap and return the
3326 // entry to the free list
3327 hashmap->remove(prev, pos, entry);
3328 destroy_entry(entry);
3330 // post the event to the profiler
3331 if (post_object_free) {
3332 JvmtiExport::post_object_free(env(), tag);
3333 }
3335 ++freed;
3336 } else {
3337 f->do_oop(entry->object_addr());
3338 oop new_oop = entry->object();
3340 // if the object has moved then re-hash it and move its
3341 // entry to its new location.
3342 unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
3343 if (new_pos != (unsigned int)pos) {
3344 if (prev == NULL) {
3345 table[pos] = next;
3346 } else {
3347 prev->set_next(next);
3348 }
3349 if (new_pos < (unsigned int)pos) {
3350 entry->set_next(table[new_pos]);
3351 table[new_pos] = entry;
3352 } else {
3353 // Delay adding this entry to it's new position as we'd end up
3354 // hitting it again during this iteration.
3355 entry->set_next(delayed_add);
3356 delayed_add = entry;
3357 }
3358 moved++;
3359 } else {
3360 // object didn't move
3361 prev = entry;
3362 }
3363 }
3365 entry = next;
3366 }
3367 }
3369 // Re-add all the entries which were kept aside
3370 while (delayed_add != NULL) {
3371 JvmtiTagHashmapEntry* next = delayed_add->next();
3372 unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
3373 delayed_add->set_next(table[pos]);
3374 table[pos] = delayed_add;
3375 delayed_add = next;
3376 }
3378 // stats
3379 if (TraceJVMTIObjectTagging) {
3380 int post_total = hashmap->_entry_count;
3381 int pre_total = post_total + freed;
3383 tty->print_cr("(%d->%d, %d freed, %d total moves)",
3384 pre_total, post_total, freed, moved);
3385 }
3386 }