Sat, 26 Feb 2011 13:33:23 -0500
7017640: Fix for 6766644 deadlocks on some NSK tests when running with -Xcomp
Summary: Dynamic-code generated events should be deferred and processed by service thread
Reviewed-by: dsamersoff, dcubed
1 /*
2 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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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/objArrayKlass.hpp"
31 #include "oops/oop.inline2.hpp"
32 #include "prims/jvmtiEventController.hpp"
33 #include "prims/jvmtiEventController.inline.hpp"
34 #include "prims/jvmtiExport.hpp"
35 #include "prims/jvmtiImpl.hpp"
36 #include "prims/jvmtiTagMap.hpp"
37 #include "runtime/biasedLocking.hpp"
38 #include "runtime/javaCalls.hpp"
39 #include "runtime/jniHandles.hpp"
40 #include "runtime/mutex.hpp"
41 #include "runtime/mutexLocker.hpp"
42 #include "runtime/reflectionUtils.hpp"
43 #include "runtime/vframe.hpp"
44 #include "runtime/vmThread.hpp"
45 #include "runtime/vm_operations.hpp"
46 #include "services/serviceUtil.hpp"
47 #ifndef SERIALGC
48 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
49 #endif
51 // JvmtiTagHashmapEntry
52 //
53 // Each entry encapsulates a reference to the tagged object
54 // and the tag value. In addition an entry includes a next pointer which
55 // is used to chain entries together.
57 class JvmtiTagHashmapEntry : public CHeapObj {
58 private:
59 friend class JvmtiTagMap;
61 oop _object; // tagged object
62 jlong _tag; // the tag
63 JvmtiTagHashmapEntry* _next; // next on the list
65 inline void init(oop object, jlong tag) {
66 _object = object;
67 _tag = tag;
68 _next = NULL;
69 }
71 // constructor
72 JvmtiTagHashmapEntry(oop object, jlong tag) { init(object, tag); }
74 public:
76 // accessor methods
77 inline oop object() const { return _object; }
78 inline oop* object_addr() { return &_object; }
79 inline jlong tag() const { return _tag; }
81 inline void set_tag(jlong tag) {
82 assert(tag != 0, "can't be zero");
83 _tag = tag;
84 }
86 inline JvmtiTagHashmapEntry* next() const { return _next; }
87 inline void set_next(JvmtiTagHashmapEntry* next) { _next = next; }
88 };
91 // JvmtiTagHashmap
92 //
93 // A hashmap is essentially a table of pointers to entries. Entries
94 // are hashed to a location, or position in the table, and then
95 // chained from that location. The "key" for hashing is address of
96 // the object, or oop. The "value" is the tag value.
97 //
98 // A hashmap maintains a count of the number entries in the hashmap
99 // and resizes if the number of entries exceeds a given threshold.
100 // The threshold is specified as a percentage of the size - for
101 // example a threshold of 0.75 will trigger the hashmap to resize
102 // if the number of entries is >75% of table size.
103 //
104 // A hashmap provides functions for adding, removing, and finding
105 // entries. It also provides a function to iterate over all entries
106 // in the hashmap.
108 class JvmtiTagHashmap : public CHeapObj {
109 private:
110 friend class JvmtiTagMap;
112 enum {
113 small_trace_threshold = 10000, // threshold for tracing
114 medium_trace_threshold = 100000,
115 large_trace_threshold = 1000000,
116 initial_trace_threshold = small_trace_threshold
117 };
119 static int _sizes[]; // array of possible hashmap sizes
120 int _size; // actual size of the table
121 int _size_index; // index into size table
123 int _entry_count; // number of entries in the hashmap
125 float _load_factor; // load factor as a % of the size
126 int _resize_threshold; // computed threshold to trigger resizing.
127 bool _resizing_enabled; // indicates if hashmap can resize
129 int _trace_threshold; // threshold for trace messages
131 JvmtiTagHashmapEntry** _table; // the table of entries.
133 // private accessors
134 int resize_threshold() const { return _resize_threshold; }
135 int trace_threshold() const { return _trace_threshold; }
137 // initialize the hashmap
138 void init(int size_index=0, float load_factor=4.0f) {
139 int initial_size = _sizes[size_index];
140 _size_index = size_index;
141 _size = initial_size;
142 _entry_count = 0;
143 if (TraceJVMTIObjectTagging) {
144 _trace_threshold = initial_trace_threshold;
145 } else {
146 _trace_threshold = -1;
147 }
148 _load_factor = load_factor;
149 _resize_threshold = (int)(_load_factor * _size);
150 _resizing_enabled = true;
151 size_t s = initial_size * sizeof(JvmtiTagHashmapEntry*);
152 _table = (JvmtiTagHashmapEntry**)os::malloc(s);
153 if (_table == NULL) {
154 vm_exit_out_of_memory(s, "unable to allocate initial hashtable for jvmti object tags");
155 }
156 for (int i=0; i<initial_size; i++) {
157 _table[i] = NULL;
158 }
159 }
161 // hash a given key (oop) with the specified size
162 static unsigned int hash(oop key, int size) {
163 // shift right to get better distribution (as these bits will be zero
164 // with aligned addresses)
165 unsigned int addr = (unsigned int)((intptr_t)key);
166 #ifdef _LP64
167 return (addr >> 3) % size;
168 #else
169 return (addr >> 2) % size;
170 #endif
171 }
173 // hash a given key (oop)
174 unsigned int hash(oop key) {
175 return hash(key, _size);
176 }
178 // resize the hashmap - allocates a large table and re-hashes
179 // all entries into the new table.
180 void resize() {
181 int new_size_index = _size_index+1;
182 int new_size = _sizes[new_size_index];
183 if (new_size < 0) {
184 // hashmap already at maximum capacity
185 return;
186 }
188 // allocate new table
189 size_t s = new_size * sizeof(JvmtiTagHashmapEntry*);
190 JvmtiTagHashmapEntry** new_table = (JvmtiTagHashmapEntry**)os::malloc(s);
191 if (new_table == NULL) {
192 warning("unable to allocate larger hashtable for jvmti object tags");
193 set_resizing_enabled(false);
194 return;
195 }
197 // initialize new table
198 int i;
199 for (i=0; i<new_size; i++) {
200 new_table[i] = NULL;
201 }
203 // rehash all entries into the new table
204 for (i=0; i<_size; i++) {
205 JvmtiTagHashmapEntry* entry = _table[i];
206 while (entry != NULL) {
207 JvmtiTagHashmapEntry* next = entry->next();
208 oop key = entry->object();
209 assert(key != NULL, "jni weak reference cleared!!");
210 unsigned int h = hash(key, new_size);
211 JvmtiTagHashmapEntry* anchor = new_table[h];
212 if (anchor == NULL) {
213 new_table[h] = entry;
214 entry->set_next(NULL);
215 } else {
216 entry->set_next(anchor);
217 new_table[h] = entry;
218 }
219 entry = next;
220 }
221 }
223 // free old table and update settings.
224 os::free((void*)_table);
225 _table = new_table;
226 _size_index = new_size_index;
227 _size = new_size;
229 // compute new resize threshold
230 _resize_threshold = (int)(_load_factor * _size);
231 }
234 // internal remove function - remove an entry at a given position in the
235 // table.
236 inline void remove(JvmtiTagHashmapEntry* prev, int pos, JvmtiTagHashmapEntry* entry) {
237 assert(pos >= 0 && pos < _size, "out of range");
238 if (prev == NULL) {
239 _table[pos] = entry->next();
240 } else {
241 prev->set_next(entry->next());
242 }
243 assert(_entry_count > 0, "checking");
244 _entry_count--;
245 }
247 // resizing switch
248 bool is_resizing_enabled() const { return _resizing_enabled; }
249 void set_resizing_enabled(bool enable) { _resizing_enabled = enable; }
251 // debugging
252 void print_memory_usage();
253 void compute_next_trace_threshold();
255 public:
257 // create a JvmtiTagHashmap of a preferred size and optionally a load factor.
258 // The preferred size is rounded down to an actual size.
259 JvmtiTagHashmap(int size, float load_factor=0.0f) {
260 int i=0;
261 while (_sizes[i] < size) {
262 if (_sizes[i] < 0) {
263 assert(i > 0, "sanity check");
264 i--;
265 break;
266 }
267 i++;
268 }
270 // if a load factor is specified then use it, otherwise use default
271 if (load_factor > 0.01f) {
272 init(i, load_factor);
273 } else {
274 init(i);
275 }
276 }
278 // create a JvmtiTagHashmap with default settings
279 JvmtiTagHashmap() {
280 init();
281 }
283 // release table when JvmtiTagHashmap destroyed
284 ~JvmtiTagHashmap() {
285 if (_table != NULL) {
286 os::free((void*)_table);
287 _table = NULL;
288 }
289 }
291 // accessors
292 int size() const { return _size; }
293 JvmtiTagHashmapEntry** table() const { return _table; }
294 int entry_count() const { return _entry_count; }
296 // find an entry in the hashmap, returns NULL if not found.
297 inline JvmtiTagHashmapEntry* find(oop key) {
298 unsigned int h = hash(key);
299 JvmtiTagHashmapEntry* entry = _table[h];
300 while (entry != NULL) {
301 if (entry->object() == key) {
302 return entry;
303 }
304 entry = entry->next();
305 }
306 return NULL;
307 }
310 // add a new entry to hashmap
311 inline void add(oop key, JvmtiTagHashmapEntry* entry) {
312 assert(key != NULL, "checking");
313 assert(find(key) == NULL, "duplicate detected");
314 unsigned int h = hash(key);
315 JvmtiTagHashmapEntry* anchor = _table[h];
316 if (anchor == NULL) {
317 _table[h] = entry;
318 entry->set_next(NULL);
319 } else {
320 entry->set_next(anchor);
321 _table[h] = entry;
322 }
324 _entry_count++;
325 if (trace_threshold() > 0 && entry_count() >= trace_threshold()) {
326 assert(TraceJVMTIObjectTagging, "should only get here when tracing");
327 print_memory_usage();
328 compute_next_trace_threshold();
329 }
331 // if the number of entries exceed the threshold then resize
332 if (entry_count() > resize_threshold() && is_resizing_enabled()) {
333 resize();
334 }
335 }
337 // remove an entry with the given key.
338 inline JvmtiTagHashmapEntry* remove(oop key) {
339 unsigned int h = hash(key);
340 JvmtiTagHashmapEntry* entry = _table[h];
341 JvmtiTagHashmapEntry* prev = NULL;
342 while (entry != NULL) {
343 if (key == entry->object()) {
344 break;
345 }
346 prev = entry;
347 entry = entry->next();
348 }
349 if (entry != NULL) {
350 remove(prev, h, entry);
351 }
352 return entry;
353 }
355 // iterate over all entries in the hashmap
356 void entry_iterate(JvmtiTagHashmapEntryClosure* closure);
357 };
359 // possible hashmap sizes - odd primes that roughly double in size.
360 // To avoid excessive resizing the odd primes from 4801-76831 and
361 // 76831-307261 have been removed. The list must be terminated by -1.
362 int JvmtiTagHashmap::_sizes[] = { 4801, 76831, 307261, 614563, 1228891,
363 2457733, 4915219, 9830479, 19660831, 39321619, 78643219, -1 };
366 // A supporting class for iterating over all entries in Hashmap
367 class JvmtiTagHashmapEntryClosure {
368 public:
369 virtual void do_entry(JvmtiTagHashmapEntry* entry) = 0;
370 };
373 // iterate over all entries in the hashmap
374 void JvmtiTagHashmap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
375 for (int i=0; i<_size; i++) {
376 JvmtiTagHashmapEntry* entry = _table[i];
377 JvmtiTagHashmapEntry* prev = NULL;
378 while (entry != NULL) {
379 // obtain the next entry before invoking do_entry - this is
380 // necessary because do_entry may remove the entry from the
381 // hashmap.
382 JvmtiTagHashmapEntry* next = entry->next();
383 closure->do_entry(entry);
384 entry = next;
385 }
386 }
387 }
389 // debugging
390 void JvmtiTagHashmap::print_memory_usage() {
391 intptr_t p = (intptr_t)this;
392 tty->print("[JvmtiTagHashmap @ " INTPTR_FORMAT, p);
394 // table + entries in KB
395 int hashmap_usage = (size()*sizeof(JvmtiTagHashmapEntry*) +
396 entry_count()*sizeof(JvmtiTagHashmapEntry))/K;
398 int weak_globals_usage = (int)(JNIHandles::weak_global_handle_memory_usage()/K);
399 tty->print_cr(", %d entries (%d KB) <JNI weak globals: %d KB>]",
400 entry_count(), hashmap_usage, weak_globals_usage);
401 }
403 // compute threshold for the next trace message
404 void JvmtiTagHashmap::compute_next_trace_threshold() {
405 if (trace_threshold() < medium_trace_threshold) {
406 _trace_threshold += small_trace_threshold;
407 } else {
408 if (trace_threshold() < large_trace_threshold) {
409 _trace_threshold += medium_trace_threshold;
410 } else {
411 _trace_threshold += large_trace_threshold;
412 }
413 }
414 }
416 // create a JvmtiTagMap
417 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
418 _env(env),
419 _lock(Mutex::nonleaf+2, "JvmtiTagMap._lock", false),
420 _free_entries(NULL),
421 _free_entries_count(0)
422 {
423 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
424 assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
426 _hashmap = new JvmtiTagHashmap();
428 // finally add us to the environment
429 ((JvmtiEnvBase *)env)->set_tag_map(this);
430 }
433 // destroy a JvmtiTagMap
434 JvmtiTagMap::~JvmtiTagMap() {
436 // no lock acquired as we assume the enclosing environment is
437 // also being destroryed.
438 ((JvmtiEnvBase *)_env)->set_tag_map(NULL);
440 JvmtiTagHashmapEntry** table = _hashmap->table();
441 for (int j = 0; j < _hashmap->size(); j++) {
442 JvmtiTagHashmapEntry* entry = table[j];
443 while (entry != NULL) {
444 JvmtiTagHashmapEntry* next = entry->next();
445 delete entry;
446 entry = next;
447 }
448 }
450 // finally destroy the hashmap
451 delete _hashmap;
452 _hashmap = NULL;
454 // remove any entries on the free list
455 JvmtiTagHashmapEntry* entry = _free_entries;
456 while (entry != NULL) {
457 JvmtiTagHashmapEntry* next = entry->next();
458 delete entry;
459 entry = next;
460 }
461 _free_entries = NULL;
462 }
464 // create a hashmap entry
465 // - if there's an entry on the (per-environment) free list then this
466 // is returned. Otherwise an new entry is allocated.
467 JvmtiTagHashmapEntry* JvmtiTagMap::create_entry(oop ref, jlong tag) {
468 assert(Thread::current()->is_VM_thread() || is_locked(), "checking");
469 JvmtiTagHashmapEntry* entry;
470 if (_free_entries == NULL) {
471 entry = new JvmtiTagHashmapEntry(ref, tag);
472 } else {
473 assert(_free_entries_count > 0, "mismatched _free_entries_count");
474 _free_entries_count--;
475 entry = _free_entries;
476 _free_entries = entry->next();
477 entry->init(ref, tag);
478 }
479 return entry;
480 }
482 // destroy an entry by returning it to the free list
483 void JvmtiTagMap::destroy_entry(JvmtiTagHashmapEntry* entry) {
484 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
485 // limit the size of the free list
486 if (_free_entries_count >= max_free_entries) {
487 delete entry;
488 } else {
489 entry->set_next(_free_entries);
490 _free_entries = entry;
491 _free_entries_count++;
492 }
493 }
495 // returns the tag map for the given environments. If the tag map
496 // doesn't exist then it is created.
497 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
498 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
499 if (tag_map == NULL) {
500 MutexLocker mu(JvmtiThreadState_lock);
501 tag_map = ((JvmtiEnvBase*)env)->tag_map();
502 if (tag_map == NULL) {
503 tag_map = new JvmtiTagMap(env);
504 }
505 } else {
506 CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
507 }
508 return tag_map;
509 }
511 // iterate over all entries in the tag map.
512 void JvmtiTagMap::entry_iterate(JvmtiTagHashmapEntryClosure* closure) {
513 hashmap()->entry_iterate(closure);
514 }
516 // returns true if the hashmaps are empty
517 bool JvmtiTagMap::is_empty() {
518 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
519 return hashmap()->entry_count() == 0;
520 }
523 // Return the tag value for an object, or 0 if the object is
524 // not tagged
525 //
526 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) {
527 JvmtiTagHashmapEntry* entry = tag_map->hashmap()->find(o);
528 if (entry == NULL) {
529 return 0;
530 } else {
531 return entry->tag();
532 }
533 }
535 // If the object is a java.lang.Class then return the klassOop,
536 // otherwise return the original object
537 static inline oop klassOop_if_java_lang_Class(oop o) {
538 if (o->klass() == SystemDictionary::Class_klass()) {
539 if (!java_lang_Class::is_primitive(o)) {
540 o = (oop)java_lang_Class::as_klassOop(o);
541 assert(o != NULL, "class for non-primitive mirror must exist");
542 }
543 }
544 return o;
545 }
547 // A CallbackWrapper is a support class for querying and tagging an object
548 // around a callback to a profiler. The constructor does pre-callback
549 // work to get the tag value, klass tag value, ... and the destructor
550 // does the post-callback work of tagging or untagging the object.
551 //
552 // {
553 // CallbackWrapper wrapper(tag_map, o);
554 //
555 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
556 //
557 // } // wrapper goes out of scope here which results in the destructor
558 // checking to see if the object has been tagged, untagged, or the
559 // tag value has changed.
560 //
561 class CallbackWrapper : public StackObj {
562 private:
563 JvmtiTagMap* _tag_map;
564 JvmtiTagHashmap* _hashmap;
565 JvmtiTagHashmapEntry* _entry;
566 oop _o;
567 jlong _obj_size;
568 jlong _obj_tag;
569 klassOop _klass; // the object's class
570 jlong _klass_tag;
572 protected:
573 JvmtiTagMap* tag_map() const { return _tag_map; }
575 // invoked post-callback to tag, untag, or update the tag of an object
576 void inline post_callback_tag_update(oop o, JvmtiTagHashmap* hashmap,
577 JvmtiTagHashmapEntry* entry, jlong obj_tag);
578 public:
579 CallbackWrapper(JvmtiTagMap* tag_map, oop o) {
580 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
581 "MT unsafe or must be VM thread");
583 // for Classes the klassOop is tagged
584 _o = klassOop_if_java_lang_Class(o);
586 // object size
587 _obj_size = _o->size() * wordSize;
589 // record the context
590 _tag_map = tag_map;
591 _hashmap = tag_map->hashmap();
592 _entry = _hashmap->find(_o);
594 // get object tag
595 _obj_tag = (_entry == NULL) ? 0 : _entry->tag();
597 // get the class and the class's tag value
598 if (_o == o) {
599 _klass = _o->klass();
600 } else {
601 // if the object represents a runtime class then use the
602 // tag for java.lang.Class
603 _klass = SystemDictionary::Class_klass();
604 }
605 _klass_tag = tag_for(tag_map, _klass);
606 }
608 ~CallbackWrapper() {
609 post_callback_tag_update(_o, _hashmap, _entry, _obj_tag);
610 }
612 inline jlong* obj_tag_p() { return &_obj_tag; }
613 inline jlong obj_size() const { return _obj_size; }
614 inline jlong obj_tag() const { return _obj_tag; }
615 inline klassOop klass() const { return _klass; }
616 inline jlong klass_tag() const { return _klass_tag; }
617 };
621 // callback post-callback to tag, untag, or update the tag of an object
622 void inline CallbackWrapper::post_callback_tag_update(oop o,
623 JvmtiTagHashmap* hashmap,
624 JvmtiTagHashmapEntry* entry,
625 jlong obj_tag) {
626 if (entry == NULL) {
627 if (obj_tag != 0) {
628 // callback has tagged the object
629 assert(Thread::current()->is_VM_thread(), "must be VMThread");
630 entry = tag_map()->create_entry(o, obj_tag);
631 hashmap->add(o, entry);
632 }
633 } else {
634 // object was previously tagged - the callback may have untagged
635 // the object or changed the tag value
636 if (obj_tag == 0) {
638 JvmtiTagHashmapEntry* entry_removed = hashmap->remove(o);
639 assert(entry_removed == entry, "checking");
640 tag_map()->destroy_entry(entry);
642 } else {
643 if (obj_tag != entry->tag()) {
644 entry->set_tag(obj_tag);
645 }
646 }
647 }
648 }
650 // An extended CallbackWrapper used when reporting an object reference
651 // to the agent.
652 //
653 // {
654 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
655 //
656 // (*callback)(wrapper.klass_tag(),
657 // wrapper.obj_size(),
658 // wrapper.obj_tag_p()
659 // wrapper.referrer_tag_p(), ...)
660 //
661 // } // wrapper goes out of scope here which results in the destructor
662 // checking to see if the referrer object has been tagged, untagged,
663 // or the tag value has changed.
664 //
665 class TwoOopCallbackWrapper : public CallbackWrapper {
666 private:
667 bool _is_reference_to_self;
668 JvmtiTagHashmap* _referrer_hashmap;
669 JvmtiTagHashmapEntry* _referrer_entry;
670 oop _referrer;
671 jlong _referrer_obj_tag;
672 jlong _referrer_klass_tag;
673 jlong* _referrer_tag_p;
675 bool is_reference_to_self() const { return _is_reference_to_self; }
677 public:
678 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) :
679 CallbackWrapper(tag_map, o)
680 {
681 // self reference needs to be handled in a special way
682 _is_reference_to_self = (referrer == o);
684 if (_is_reference_to_self) {
685 _referrer_klass_tag = klass_tag();
686 _referrer_tag_p = obj_tag_p();
687 } else {
688 // for Classes the klassOop is tagged
689 _referrer = klassOop_if_java_lang_Class(referrer);
690 // record the context
691 _referrer_hashmap = tag_map->hashmap();
692 _referrer_entry = _referrer_hashmap->find(_referrer);
694 // get object tag
695 _referrer_obj_tag = (_referrer_entry == NULL) ? 0 : _referrer_entry->tag();
696 _referrer_tag_p = &_referrer_obj_tag;
698 // get referrer class tag.
699 klassOop k = (_referrer == referrer) ? // Check if referrer is a class...
700 _referrer->klass() // No, just get its class
701 : SystemDictionary::Class_klass(); // Yes, its class is Class
702 _referrer_klass_tag = tag_for(tag_map, k);
703 }
704 }
706 ~TwoOopCallbackWrapper() {
707 if (!is_reference_to_self()){
708 post_callback_tag_update(_referrer,
709 _referrer_hashmap,
710 _referrer_entry,
711 _referrer_obj_tag);
712 }
713 }
715 // address of referrer tag
716 // (for a self reference this will return the same thing as obj_tag_p())
717 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
719 // referrer's class tag
720 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
721 };
723 // tag an object
724 //
725 // This function is performance critical. If many threads attempt to tag objects
726 // around the same time then it's possible that the Mutex associated with the
727 // tag map will be a hot lock.
728 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
729 MutexLocker ml(lock());
731 // resolve the object
732 oop o = JNIHandles::resolve_non_null(object);
734 // for Classes we tag the klassOop
735 o = klassOop_if_java_lang_Class(o);
737 // see if the object is already tagged
738 JvmtiTagHashmap* hashmap = _hashmap;
739 JvmtiTagHashmapEntry* entry = hashmap->find(o);
741 // if the object is not already tagged then we tag it
742 if (entry == NULL) {
743 if (tag != 0) {
744 entry = create_entry(o, tag);
745 hashmap->add(o, entry);
746 } else {
747 // no-op
748 }
749 } else {
750 // if the object is already tagged then we either update
751 // the tag (if a new tag value has been provided)
752 // or remove the object if the new tag value is 0.
753 if (tag == 0) {
754 hashmap->remove(o);
755 destroy_entry(entry);
756 } else {
757 entry->set_tag(tag);
758 }
759 }
760 }
762 // get the tag for an object
763 jlong JvmtiTagMap::get_tag(jobject object) {
764 MutexLocker ml(lock());
766 // resolve the object
767 oop o = JNIHandles::resolve_non_null(object);
769 // for Classes get the tag from the klassOop
770 return tag_for(this, klassOop_if_java_lang_Class(o));
771 }
774 // Helper class used to describe the static or instance fields of a class.
775 // For each field it holds the field index (as defined by the JVMTI specification),
776 // the field type, and the offset.
778 class ClassFieldDescriptor: public CHeapObj {
779 private:
780 int _field_index;
781 int _field_offset;
782 char _field_type;
783 public:
784 ClassFieldDescriptor(int index, char type, int offset) :
785 _field_index(index), _field_type(type), _field_offset(offset) {
786 }
787 int field_index() const { return _field_index; }
788 char field_type() const { return _field_type; }
789 int field_offset() const { return _field_offset; }
790 };
792 class ClassFieldMap: public CHeapObj {
793 private:
794 enum {
795 initial_field_count = 5
796 };
798 // list of field descriptors
799 GrowableArray<ClassFieldDescriptor*>* _fields;
801 // constructor
802 ClassFieldMap();
804 // add a field
805 void add(int index, char type, int offset);
807 // returns the field count for the given class
808 static int compute_field_count(instanceKlassHandle ikh);
810 public:
811 ~ClassFieldMap();
813 // access
814 int field_count() { return _fields->length(); }
815 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
817 // functions to create maps of static or instance fields
818 static ClassFieldMap* create_map_of_static_fields(klassOop k);
819 static ClassFieldMap* create_map_of_instance_fields(oop obj);
820 };
822 ClassFieldMap::ClassFieldMap() {
823 _fields = new (ResourceObj::C_HEAP) GrowableArray<ClassFieldDescriptor*>(initial_field_count, true);
824 }
826 ClassFieldMap::~ClassFieldMap() {
827 for (int i=0; i<_fields->length(); i++) {
828 delete _fields->at(i);
829 }
830 delete _fields;
831 }
833 void ClassFieldMap::add(int index, char type, int offset) {
834 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset);
835 _fields->append(field);
836 }
838 // Returns a heap allocated ClassFieldMap to describe the static fields
839 // of the given class.
840 //
841 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(klassOop k) {
842 HandleMark hm;
843 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), k);
845 // create the field map
846 ClassFieldMap* field_map = new ClassFieldMap();
848 FilteredFieldStream f(ikh, false, false);
849 int max_field_index = f.field_count()-1;
851 int index = 0;
852 for (FilteredFieldStream fld(ikh, true, true); !fld.eos(); fld.next(), index++) {
853 // ignore instance fields
854 if (!fld.access_flags().is_static()) {
855 continue;
856 }
857 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
858 }
859 return field_map;
860 }
862 // Returns a heap allocated ClassFieldMap to describe the instance fields
863 // of the given class. All instance fields are included (this means public
864 // and private fields declared in superclasses and superinterfaces too).
865 //
866 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) {
867 HandleMark hm;
868 instanceKlassHandle ikh = instanceKlassHandle(Thread::current(), obj->klass());
870 // create the field map
871 ClassFieldMap* field_map = new ClassFieldMap();
873 FilteredFieldStream f(ikh, false, false);
875 int max_field_index = f.field_count()-1;
877 int index = 0;
878 for (FilteredFieldStream fld(ikh, false, false); !fld.eos(); fld.next(), index++) {
879 // ignore static fields
880 if (fld.access_flags().is_static()) {
881 continue;
882 }
883 field_map->add(max_field_index - index, fld.signature()->byte_at(0), fld.offset());
884 }
886 return field_map;
887 }
889 // Helper class used to cache a ClassFileMap for the instance fields of
890 // a cache. A JvmtiCachedClassFieldMap can be cached by an instanceKlass during
891 // heap iteration and avoid creating a field map for each object in the heap
892 // (only need to create the map when the first instance of a class is encountered).
893 //
894 class JvmtiCachedClassFieldMap : public CHeapObj {
895 private:
896 enum {
897 initial_class_count = 200
898 };
899 ClassFieldMap* _field_map;
901 ClassFieldMap* field_map() const { return _field_map; }
903 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
904 ~JvmtiCachedClassFieldMap();
906 static GrowableArray<instanceKlass*>* _class_list;
907 static void add_to_class_list(instanceKlass* ik);
909 public:
910 // returns the field map for a given object (returning map cached
911 // by instanceKlass if possible
912 static ClassFieldMap* get_map_of_instance_fields(oop obj);
914 // removes the field map from all instanceKlasses - should be
915 // called before VM operation completes
916 static void clear_cache();
918 // returns the number of ClassFieldMap cached by instanceKlasses
919 static int cached_field_map_count();
920 };
922 GrowableArray<instanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
924 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
925 _field_map = field_map;
926 }
928 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
929 if (_field_map != NULL) {
930 delete _field_map;
931 }
932 }
934 // Marker class to ensure that the class file map cache is only used in a defined
935 // scope.
936 class ClassFieldMapCacheMark : public StackObj {
937 private:
938 static bool _is_active;
939 public:
940 ClassFieldMapCacheMark() {
941 assert(Thread::current()->is_VM_thread(), "must be VMThread");
942 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
943 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
944 _is_active = true;
945 }
946 ~ClassFieldMapCacheMark() {
947 JvmtiCachedClassFieldMap::clear_cache();
948 _is_active = false;
949 }
950 static bool is_active() { return _is_active; }
951 };
953 bool ClassFieldMapCacheMark::_is_active;
956 // record that the given instanceKlass is caching a field map
957 void JvmtiCachedClassFieldMap::add_to_class_list(instanceKlass* ik) {
958 if (_class_list == NULL) {
959 _class_list = new (ResourceObj::C_HEAP) GrowableArray<instanceKlass*>(initial_class_count, true);
960 }
961 _class_list->push(ik);
962 }
964 // returns the instance field map for the given object
965 // (returns field map cached by the instanceKlass if possible)
966 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) {
967 assert(Thread::current()->is_VM_thread(), "must be VMThread");
968 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
970 klassOop k = obj->klass();
971 instanceKlass* ik = instanceKlass::cast(k);
973 // return cached map if possible
974 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
975 if (cached_map != NULL) {
976 assert(cached_map->field_map() != NULL, "missing field list");
977 return cached_map->field_map();
978 } else {
979 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj);
980 cached_map = new JvmtiCachedClassFieldMap(field_map);
981 ik->set_jvmti_cached_class_field_map(cached_map);
982 add_to_class_list(ik);
983 return field_map;
984 }
985 }
987 // remove the fields maps cached from all instanceKlasses
988 void JvmtiCachedClassFieldMap::clear_cache() {
989 assert(Thread::current()->is_VM_thread(), "must be VMThread");
990 if (_class_list != NULL) {
991 for (int i = 0; i < _class_list->length(); i++) {
992 instanceKlass* ik = _class_list->at(i);
993 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
994 assert(cached_map != NULL, "should not be NULL");
995 ik->set_jvmti_cached_class_field_map(NULL);
996 delete cached_map; // deletes the encapsulated field map
997 }
998 delete _class_list;
999 _class_list = NULL;
1000 }
1001 }
1003 // returns the number of ClassFieldMap cached by instanceKlasses
1004 int JvmtiCachedClassFieldMap::cached_field_map_count() {
1005 return (_class_list == NULL) ? 0 : _class_list->length();
1006 }
1008 // helper function to indicate if an object is filtered by its tag or class tag
1009 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
1010 jlong klass_tag,
1011 int heap_filter) {
1012 // apply the heap filter
1013 if (obj_tag != 0) {
1014 // filter out tagged objects
1015 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
1016 } else {
1017 // filter out untagged objects
1018 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
1019 }
1020 if (klass_tag != 0) {
1021 // filter out objects with tagged classes
1022 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
1023 } else {
1024 // filter out objects with untagged classes.
1025 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
1026 }
1027 return false;
1028 }
1030 // helper function to indicate if an object is filtered by a klass filter
1031 static inline bool is_filtered_by_klass_filter(oop obj, KlassHandle klass_filter) {
1032 if (!klass_filter.is_null()) {
1033 if (obj->klass() != klass_filter()) {
1034 return true;
1035 }
1036 }
1037 return false;
1038 }
1040 // helper function to tell if a field is a primitive field or not
1041 static inline bool is_primitive_field_type(char type) {
1042 return (type != 'L' && type != '[');
1043 }
1045 // helper function to copy the value from location addr to jvalue.
1046 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
1047 switch (value_type) {
1048 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
1049 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
1050 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
1051 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
1052 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
1053 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
1054 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
1055 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
1056 default: ShouldNotReachHere();
1057 }
1058 }
1060 // helper function to invoke string primitive value callback
1061 // returns visit control flags
1062 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
1063 CallbackWrapper* wrapper,
1064 oop str,
1065 void* user_data)
1066 {
1067 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
1069 // get the string value and length
1070 // (string value may be offset from the base)
1071 int s_len = java_lang_String::length(str);
1072 typeArrayOop s_value = java_lang_String::value(str);
1073 int s_offset = java_lang_String::offset(str);
1074 jchar* value;
1075 if (s_len > 0) {
1076 value = s_value->char_at_addr(s_offset);
1077 } else {
1078 value = (jchar*) s_value->base(T_CHAR);
1079 }
1081 // invoke the callback
1082 return (*cb)(wrapper->klass_tag(),
1083 wrapper->obj_size(),
1084 wrapper->obj_tag_p(),
1085 value,
1086 (jint)s_len,
1087 user_data);
1088 }
1090 // helper function to invoke string primitive value callback
1091 // returns visit control flags
1092 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
1093 CallbackWrapper* wrapper,
1094 oop obj,
1095 void* user_data)
1096 {
1097 assert(obj->is_typeArray(), "not a primitive array");
1099 // get base address of first element
1100 typeArrayOop array = typeArrayOop(obj);
1101 BasicType type = typeArrayKlass::cast(array->klass())->element_type();
1102 void* elements = array->base(type);
1104 // jvmtiPrimitiveType is defined so this mapping is always correct
1105 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
1107 return (*cb)(wrapper->klass_tag(),
1108 wrapper->obj_size(),
1109 wrapper->obj_tag_p(),
1110 (jint)array->length(),
1111 elem_type,
1112 elements,
1113 user_data);
1114 }
1116 // helper function to invoke the primitive field callback for all static fields
1117 // of a given class
1118 static jint invoke_primitive_field_callback_for_static_fields
1119 (CallbackWrapper* wrapper,
1120 oop obj,
1121 jvmtiPrimitiveFieldCallback cb,
1122 void* user_data)
1123 {
1124 // for static fields only the index will be set
1125 static jvmtiHeapReferenceInfo reference_info = { 0 };
1127 assert(obj->klass() == SystemDictionary::Class_klass(), "not a class");
1128 if (java_lang_Class::is_primitive(obj)) {
1129 return 0;
1130 }
1131 klassOop k = java_lang_Class::as_klassOop(obj);
1132 Klass* klass = k->klass_part();
1134 // ignore classes for object and type arrays
1135 if (!klass->oop_is_instance()) {
1136 return 0;
1137 }
1139 // ignore classes which aren't linked yet
1140 instanceKlass* ik = instanceKlass::cast(k);
1141 if (!ik->is_linked()) {
1142 return 0;
1143 }
1145 // get the field map
1146 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
1148 // invoke the callback for each static primitive field
1149 for (int i=0; i<field_map->field_count(); i++) {
1150 ClassFieldDescriptor* field = field_map->field_at(i);
1152 // ignore non-primitive fields
1153 char type = field->field_type();
1154 if (!is_primitive_field_type(type)) {
1155 continue;
1156 }
1157 // one-to-one mapping
1158 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1160 // get offset and field value
1161 int offset = field->field_offset();
1162 address addr = (address)k + offset;
1163 jvalue value;
1164 copy_to_jvalue(&value, addr, value_type);
1166 // field index
1167 reference_info.field.index = field->field_index();
1169 // invoke the callback
1170 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1171 &reference_info,
1172 wrapper->klass_tag(),
1173 wrapper->obj_tag_p(),
1174 value,
1175 value_type,
1176 user_data);
1177 if (res & JVMTI_VISIT_ABORT) {
1178 delete field_map;
1179 return res;
1180 }
1181 }
1183 delete field_map;
1184 return 0;
1185 }
1187 // helper function to invoke the primitive field callback for all instance fields
1188 // of a given object
1189 static jint invoke_primitive_field_callback_for_instance_fields(
1190 CallbackWrapper* wrapper,
1191 oop obj,
1192 jvmtiPrimitiveFieldCallback cb,
1193 void* user_data)
1194 {
1195 // for instance fields only the index will be set
1196 static jvmtiHeapReferenceInfo reference_info = { 0 };
1198 // get the map of the instance fields
1199 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj);
1201 // invoke the callback for each instance primitive field
1202 for (int i=0; i<fields->field_count(); i++) {
1203 ClassFieldDescriptor* field = fields->field_at(i);
1205 // ignore non-primitive fields
1206 char type = field->field_type();
1207 if (!is_primitive_field_type(type)) {
1208 continue;
1209 }
1210 // one-to-one mapping
1211 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1213 // get offset and field value
1214 int offset = field->field_offset();
1215 address addr = (address)obj + offset;
1216 jvalue value;
1217 copy_to_jvalue(&value, addr, value_type);
1219 // field index
1220 reference_info.field.index = field->field_index();
1222 // invoke the callback
1223 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1224 &reference_info,
1225 wrapper->klass_tag(),
1226 wrapper->obj_tag_p(),
1227 value,
1228 value_type,
1229 user_data);
1230 if (res & JVMTI_VISIT_ABORT) {
1231 return res;
1232 }
1233 }
1234 return 0;
1235 }
1238 // VM operation to iterate over all objects in the heap (both reachable
1239 // and unreachable)
1240 class VM_HeapIterateOperation: public VM_Operation {
1241 private:
1242 ObjectClosure* _blk;
1243 public:
1244 VM_HeapIterateOperation(ObjectClosure* blk) { _blk = blk; }
1246 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1247 void doit() {
1248 // allows class files maps to be cached during iteration
1249 ClassFieldMapCacheMark cm;
1251 // make sure that heap is parsable (fills TLABs with filler objects)
1252 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1254 // Verify heap before iteration - if the heap gets corrupted then
1255 // JVMTI's IterateOverHeap will crash.
1256 if (VerifyBeforeIteration) {
1257 Universe::verify();
1258 }
1260 // do the iteration
1261 // If this operation encounters a bad object when using CMS,
1262 // consider using safe_object_iterate() which avoids perm gen
1263 // objects that may contain bad references.
1264 Universe::heap()->object_iterate(_blk);
1266 // when sharing is enabled we must iterate over the shared spaces
1267 if (UseSharedSpaces) {
1268 GenCollectedHeap* gch = GenCollectedHeap::heap();
1269 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
1270 gen->ro_space()->object_iterate(_blk);
1271 gen->rw_space()->object_iterate(_blk);
1272 }
1273 }
1275 };
1278 // An ObjectClosure used to support the deprecated IterateOverHeap and
1279 // IterateOverInstancesOfClass functions
1280 class IterateOverHeapObjectClosure: public ObjectClosure {
1281 private:
1282 JvmtiTagMap* _tag_map;
1283 KlassHandle _klass;
1284 jvmtiHeapObjectFilter _object_filter;
1285 jvmtiHeapObjectCallback _heap_object_callback;
1286 const void* _user_data;
1288 // accessors
1289 JvmtiTagMap* tag_map() const { return _tag_map; }
1290 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1291 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1292 KlassHandle klass() const { return _klass; }
1293 const void* user_data() const { return _user_data; }
1295 // indicates if iteration has been aborted
1296 bool _iteration_aborted;
1297 bool is_iteration_aborted() const { return _iteration_aborted; }
1298 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1300 public:
1301 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1302 KlassHandle klass,
1303 jvmtiHeapObjectFilter object_filter,
1304 jvmtiHeapObjectCallback heap_object_callback,
1305 const void* user_data) :
1306 _tag_map(tag_map),
1307 _klass(klass),
1308 _object_filter(object_filter),
1309 _heap_object_callback(heap_object_callback),
1310 _user_data(user_data),
1311 _iteration_aborted(false)
1312 {
1313 }
1315 void do_object(oop o);
1316 };
1318 // invoked for each object in the heap
1319 void IterateOverHeapObjectClosure::do_object(oop o) {
1320 // check if iteration has been halted
1321 if (is_iteration_aborted()) return;
1323 // ignore any objects that aren't visible to profiler
1324 if (!ServiceUtil::visible_oop(o)) return;
1326 // instanceof check when filtering by klass
1327 if (!klass().is_null() && !o->is_a(klass()())) {
1328 return;
1329 }
1330 // prepare for the calllback
1331 CallbackWrapper wrapper(tag_map(), o);
1333 // if the object is tagged and we're only interested in untagged objects
1334 // then don't invoke the callback. Similiarly, if the object is untagged
1335 // and we're only interested in tagged objects we skip the callback.
1336 if (wrapper.obj_tag() != 0) {
1337 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1338 } else {
1339 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1340 }
1342 // invoke the agent's callback
1343 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1344 wrapper.obj_size(),
1345 wrapper.obj_tag_p(),
1346 (void*)user_data());
1347 if (control == JVMTI_ITERATION_ABORT) {
1348 set_iteration_aborted(true);
1349 }
1350 }
1352 // An ObjectClosure used to support the IterateThroughHeap function
1353 class IterateThroughHeapObjectClosure: public ObjectClosure {
1354 private:
1355 JvmtiTagMap* _tag_map;
1356 KlassHandle _klass;
1357 int _heap_filter;
1358 const jvmtiHeapCallbacks* _callbacks;
1359 const void* _user_data;
1361 // accessor functions
1362 JvmtiTagMap* tag_map() const { return _tag_map; }
1363 int heap_filter() const { return _heap_filter; }
1364 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1365 KlassHandle klass() const { return _klass; }
1366 const void* user_data() const { return _user_data; }
1368 // indicates if the iteration has been aborted
1369 bool _iteration_aborted;
1370 bool is_iteration_aborted() const { return _iteration_aborted; }
1372 // used to check the visit control flags. If the abort flag is set
1373 // then we set the iteration aborted flag so that the iteration completes
1374 // without processing any further objects
1375 bool check_flags_for_abort(jint flags) {
1376 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1377 if (is_abort) {
1378 _iteration_aborted = true;
1379 }
1380 return is_abort;
1381 }
1383 public:
1384 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1385 KlassHandle klass,
1386 int heap_filter,
1387 const jvmtiHeapCallbacks* heap_callbacks,
1388 const void* user_data) :
1389 _tag_map(tag_map),
1390 _klass(klass),
1391 _heap_filter(heap_filter),
1392 _callbacks(heap_callbacks),
1393 _user_data(user_data),
1394 _iteration_aborted(false)
1395 {
1396 }
1398 void do_object(oop o);
1399 };
1401 // invoked for each object in the heap
1402 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1403 // check if iteration has been halted
1404 if (is_iteration_aborted()) return;
1406 // ignore any objects that aren't visible to profiler
1407 if (!ServiceUtil::visible_oop(obj)) return;
1409 // apply class filter
1410 if (is_filtered_by_klass_filter(obj, klass())) return;
1412 // prepare for callback
1413 CallbackWrapper wrapper(tag_map(), obj);
1415 // check if filtered by the heap filter
1416 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1417 return;
1418 }
1420 // for arrays we need the length, otherwise -1
1421 bool is_array = obj->is_array();
1422 int len = is_array ? arrayOop(obj)->length() : -1;
1424 // invoke the object callback (if callback is provided)
1425 if (callbacks()->heap_iteration_callback != NULL) {
1426 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1427 jint res = (*cb)(wrapper.klass_tag(),
1428 wrapper.obj_size(),
1429 wrapper.obj_tag_p(),
1430 (jint)len,
1431 (void*)user_data());
1432 if (check_flags_for_abort(res)) return;
1433 }
1435 // for objects and classes we report primitive fields if callback provided
1436 if (callbacks()->primitive_field_callback != NULL && obj->is_instance()) {
1437 jint res;
1438 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1439 if (obj->klass() == SystemDictionary::Class_klass()) {
1440 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1441 obj,
1442 cb,
1443 (void*)user_data());
1444 } else {
1445 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1446 obj,
1447 cb,
1448 (void*)user_data());
1449 }
1450 if (check_flags_for_abort(res)) return;
1451 }
1453 // string callback
1454 if (!is_array &&
1455 callbacks()->string_primitive_value_callback != NULL &&
1456 obj->klass() == SystemDictionary::String_klass()) {
1457 jint res = invoke_string_value_callback(
1458 callbacks()->string_primitive_value_callback,
1459 &wrapper,
1460 obj,
1461 (void*)user_data() );
1462 if (check_flags_for_abort(res)) return;
1463 }
1465 // array callback
1466 if (is_array &&
1467 callbacks()->array_primitive_value_callback != NULL &&
1468 obj->is_typeArray()) {
1469 jint res = invoke_array_primitive_value_callback(
1470 callbacks()->array_primitive_value_callback,
1471 &wrapper,
1472 obj,
1473 (void*)user_data() );
1474 if (check_flags_for_abort(res)) return;
1475 }
1476 };
1479 // Deprecated function to iterate over all objects in the heap
1480 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1481 KlassHandle klass,
1482 jvmtiHeapObjectCallback heap_object_callback,
1483 const void* user_data)
1484 {
1485 MutexLocker ml(Heap_lock);
1486 IterateOverHeapObjectClosure blk(this,
1487 klass,
1488 object_filter,
1489 heap_object_callback,
1490 user_data);
1491 VM_HeapIterateOperation op(&blk);
1492 VMThread::execute(&op);
1493 }
1496 // Iterates over all objects in the heap
1497 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1498 KlassHandle klass,
1499 const jvmtiHeapCallbacks* callbacks,
1500 const void* user_data)
1501 {
1502 MutexLocker ml(Heap_lock);
1503 IterateThroughHeapObjectClosure blk(this,
1504 klass,
1505 heap_filter,
1506 callbacks,
1507 user_data);
1508 VM_HeapIterateOperation op(&blk);
1509 VMThread::execute(&op);
1510 }
1512 // support class for get_objects_with_tags
1514 class TagObjectCollector : public JvmtiTagHashmapEntryClosure {
1515 private:
1516 JvmtiEnv* _env;
1517 jlong* _tags;
1518 jint _tag_count;
1520 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1521 GrowableArray<uint64_t>* _tag_results; // collected tags
1523 public:
1524 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) {
1525 _env = env;
1526 _tags = (jlong*)tags;
1527 _tag_count = tag_count;
1528 _object_results = new (ResourceObj::C_HEAP) GrowableArray<jobject>(1,true);
1529 _tag_results = new (ResourceObj::C_HEAP) GrowableArray<uint64_t>(1,true);
1530 }
1532 ~TagObjectCollector() {
1533 delete _object_results;
1534 delete _tag_results;
1535 }
1537 // for each tagged object check if the tag value matches
1538 // - if it matches then we create a JNI local reference to the object
1539 // and record the reference and tag value.
1540 //
1541 void do_entry(JvmtiTagHashmapEntry* entry) {
1542 for (int i=0; i<_tag_count; i++) {
1543 if (_tags[i] == entry->tag()) {
1544 oop o = entry->object();
1545 assert(o != NULL, "sanity check");
1547 // the mirror is tagged
1548 if (o->is_klass()) {
1549 klassOop k = (klassOop)o;
1550 o = Klass::cast(k)->java_mirror();
1551 }
1553 jobject ref = JNIHandles::make_local(JavaThread::current(), o);
1554 _object_results->append(ref);
1555 _tag_results->append((uint64_t)entry->tag());
1556 }
1557 }
1558 }
1560 // return the results from the collection
1561 //
1562 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1563 jvmtiError error;
1564 int count = _object_results->length();
1565 assert(count >= 0, "sanity check");
1567 // if object_result_ptr is not NULL then allocate the result and copy
1568 // in the object references.
1569 if (object_result_ptr != NULL) {
1570 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1571 if (error != JVMTI_ERROR_NONE) {
1572 return error;
1573 }
1574 for (int i=0; i<count; i++) {
1575 (*object_result_ptr)[i] = _object_results->at(i);
1576 }
1577 }
1579 // if tag_result_ptr is not NULL then allocate the result and copy
1580 // in the tag values.
1581 if (tag_result_ptr != NULL) {
1582 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1583 if (error != JVMTI_ERROR_NONE) {
1584 if (object_result_ptr != NULL) {
1585 _env->Deallocate((unsigned char*)object_result_ptr);
1586 }
1587 return error;
1588 }
1589 for (int i=0; i<count; i++) {
1590 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1591 }
1592 }
1594 *count_ptr = count;
1595 return JVMTI_ERROR_NONE;
1596 }
1597 };
1599 // return the list of objects with the specified tags
1600 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1601 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1603 TagObjectCollector collector(env(), tags, count);
1604 {
1605 // iterate over all tagged objects
1606 MutexLocker ml(lock());
1607 entry_iterate(&collector);
1608 }
1609 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1610 }
1613 // ObjectMarker is used to support the marking objects when walking the
1614 // heap.
1615 //
1616 // This implementation uses the existing mark bits in an object for
1617 // marking. Objects that are marked must later have their headers restored.
1618 // As most objects are unlocked and don't have their identity hash computed
1619 // we don't have to save their headers. Instead we save the headers that
1620 // are "interesting". Later when the headers are restored this implementation
1621 // restores all headers to their initial value and then restores the few
1622 // objects that had interesting headers.
1623 //
1624 // Future work: This implementation currently uses growable arrays to save
1625 // the oop and header of interesting objects. As an optimization we could
1626 // use the same technique as the GC and make use of the unused area
1627 // between top() and end().
1628 //
1630 // An ObjectClosure used to restore the mark bits of an object
1631 class RestoreMarksClosure : public ObjectClosure {
1632 public:
1633 void do_object(oop o) {
1634 if (o != NULL) {
1635 markOop mark = o->mark();
1636 if (mark->is_marked()) {
1637 o->init_mark();
1638 }
1639 }
1640 }
1641 };
1643 // ObjectMarker provides the mark and visited functions
1644 class ObjectMarker : AllStatic {
1645 private:
1646 // saved headers
1647 static GrowableArray<oop>* _saved_oop_stack;
1648 static GrowableArray<markOop>* _saved_mark_stack;
1650 public:
1651 static void init(); // initialize
1652 static void done(); // clean-up
1654 static inline void mark(oop o); // mark an object
1655 static inline bool visited(oop o); // check if object has been visited
1656 };
1658 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1659 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1661 // initialize ObjectMarker - prepares for object marking
1662 void ObjectMarker::init() {
1663 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1665 // prepare heap for iteration
1666 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1668 // create stacks for interesting headers
1669 _saved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(4000, true);
1670 _saved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
1672 if (UseBiasedLocking) {
1673 BiasedLocking::preserve_marks();
1674 }
1675 }
1677 // Object marking is done so restore object headers
1678 void ObjectMarker::done() {
1679 // iterate over all objects and restore the mark bits to
1680 // their initial value
1681 RestoreMarksClosure blk;
1682 Universe::heap()->object_iterate(&blk);
1684 // When sharing is enabled we need to restore the headers of the objects
1685 // in the readwrite space too.
1686 if (UseSharedSpaces) {
1687 GenCollectedHeap* gch = GenCollectedHeap::heap();
1688 CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
1689 gen->rw_space()->object_iterate(&blk);
1690 }
1692 // now restore the interesting headers
1693 for (int i = 0; i < _saved_oop_stack->length(); i++) {
1694 oop o = _saved_oop_stack->at(i);
1695 markOop mark = _saved_mark_stack->at(i);
1696 o->set_mark(mark);
1697 }
1699 if (UseBiasedLocking) {
1700 BiasedLocking::restore_marks();
1701 }
1703 // free the stacks
1704 delete _saved_oop_stack;
1705 delete _saved_mark_stack;
1706 }
1708 // mark an object
1709 inline void ObjectMarker::mark(oop o) {
1710 assert(Universe::heap()->is_in(o), "sanity check");
1711 assert(!o->mark()->is_marked(), "should only mark an object once");
1713 // object's mark word
1714 markOop mark = o->mark();
1716 if (mark->must_be_preserved(o)) {
1717 _saved_mark_stack->push(mark);
1718 _saved_oop_stack->push(o);
1719 }
1721 // mark the object
1722 o->set_mark(markOopDesc::prototype()->set_marked());
1723 }
1725 // return true if object is marked
1726 inline bool ObjectMarker::visited(oop o) {
1727 return o->mark()->is_marked();
1728 }
1730 // Stack allocated class to help ensure that ObjectMarker is used
1731 // correctly. Constructor initializes ObjectMarker, destructor calls
1732 // ObjectMarker's done() function to restore object headers.
1733 class ObjectMarkerController : public StackObj {
1734 public:
1735 ObjectMarkerController() {
1736 ObjectMarker::init();
1737 }
1738 ~ObjectMarkerController() {
1739 ObjectMarker::done();
1740 }
1741 };
1744 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1745 // (not performance critical as only used for roots)
1746 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1747 switch (kind) {
1748 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1749 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1750 case JVMTI_HEAP_REFERENCE_MONITOR: return JVMTI_HEAP_ROOT_MONITOR;
1751 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1752 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1753 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1754 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1755 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1756 }
1757 }
1759 // Base class for all heap walk contexts. The base class maintains a flag
1760 // to indicate if the context is valid or not.
1761 class HeapWalkContext VALUE_OBJ_CLASS_SPEC {
1762 private:
1763 bool _valid;
1764 public:
1765 HeapWalkContext(bool valid) { _valid = valid; }
1766 void invalidate() { _valid = false; }
1767 bool is_valid() const { return _valid; }
1768 };
1770 // A basic heap walk context for the deprecated heap walking functions.
1771 // The context for a basic heap walk are the callbacks and fields used by
1772 // the referrer caching scheme.
1773 class BasicHeapWalkContext: public HeapWalkContext {
1774 private:
1775 jvmtiHeapRootCallback _heap_root_callback;
1776 jvmtiStackReferenceCallback _stack_ref_callback;
1777 jvmtiObjectReferenceCallback _object_ref_callback;
1779 // used for caching
1780 oop _last_referrer;
1781 jlong _last_referrer_tag;
1783 public:
1784 BasicHeapWalkContext() : HeapWalkContext(false) { }
1786 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1787 jvmtiStackReferenceCallback stack_ref_callback,
1788 jvmtiObjectReferenceCallback object_ref_callback) :
1789 HeapWalkContext(true),
1790 _heap_root_callback(heap_root_callback),
1791 _stack_ref_callback(stack_ref_callback),
1792 _object_ref_callback(object_ref_callback),
1793 _last_referrer(NULL),
1794 _last_referrer_tag(0) {
1795 }
1797 // accessors
1798 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1799 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1800 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1802 oop last_referrer() const { return _last_referrer; }
1803 void set_last_referrer(oop referrer) { _last_referrer = referrer; }
1804 jlong last_referrer_tag() const { return _last_referrer_tag; }
1805 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1806 };
1808 // The advanced heap walk context for the FollowReferences functions.
1809 // The context is the callbacks, and the fields used for filtering.
1810 class AdvancedHeapWalkContext: public HeapWalkContext {
1811 private:
1812 jint _heap_filter;
1813 KlassHandle _klass_filter;
1814 const jvmtiHeapCallbacks* _heap_callbacks;
1816 public:
1817 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1819 AdvancedHeapWalkContext(jint heap_filter,
1820 KlassHandle klass_filter,
1821 const jvmtiHeapCallbacks* heap_callbacks) :
1822 HeapWalkContext(true),
1823 _heap_filter(heap_filter),
1824 _klass_filter(klass_filter),
1825 _heap_callbacks(heap_callbacks) {
1826 }
1828 // accessors
1829 jint heap_filter() const { return _heap_filter; }
1830 KlassHandle klass_filter() const { return _klass_filter; }
1832 const jvmtiHeapReferenceCallback heap_reference_callback() const {
1833 return _heap_callbacks->heap_reference_callback;
1834 };
1835 const jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1836 return _heap_callbacks->primitive_field_callback;
1837 }
1838 const jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1839 return _heap_callbacks->array_primitive_value_callback;
1840 }
1841 const jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1842 return _heap_callbacks->string_primitive_value_callback;
1843 }
1844 };
1846 // The CallbackInvoker is a class with static functions that the heap walk can call
1847 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1848 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1849 // mode is for the newer FollowReferences function which supports a lot of
1850 // additional callbacks.
1851 class CallbackInvoker : AllStatic {
1852 private:
1853 // heap walk styles
1854 enum { basic, advanced };
1855 static int _heap_walk_type;
1856 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1857 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1859 // context for basic style heap walk
1860 static BasicHeapWalkContext _basic_context;
1861 static BasicHeapWalkContext* basic_context() {
1862 assert(_basic_context.is_valid(), "invalid");
1863 return &_basic_context;
1864 }
1866 // context for advanced style heap walk
1867 static AdvancedHeapWalkContext _advanced_context;
1868 static AdvancedHeapWalkContext* advanced_context() {
1869 assert(_advanced_context.is_valid(), "invalid");
1870 return &_advanced_context;
1871 }
1873 // context needed for all heap walks
1874 static JvmtiTagMap* _tag_map;
1875 static const void* _user_data;
1876 static GrowableArray<oop>* _visit_stack;
1878 // accessors
1879 static JvmtiTagMap* tag_map() { return _tag_map; }
1880 static const void* user_data() { return _user_data; }
1881 static GrowableArray<oop>* visit_stack() { return _visit_stack; }
1883 // if the object hasn't been visited then push it onto the visit stack
1884 // so that it will be visited later
1885 static inline bool check_for_visit(oop obj) {
1886 if (!ObjectMarker::visited(obj)) visit_stack()->push(obj);
1887 return true;
1888 }
1890 // invoke basic style callbacks
1891 static inline bool invoke_basic_heap_root_callback
1892 (jvmtiHeapRootKind root_kind, oop obj);
1893 static inline bool invoke_basic_stack_ref_callback
1894 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1895 int slot, oop obj);
1896 static inline bool invoke_basic_object_reference_callback
1897 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index);
1899 // invoke advanced style callbacks
1900 static inline bool invoke_advanced_heap_root_callback
1901 (jvmtiHeapReferenceKind ref_kind, oop obj);
1902 static inline bool invoke_advanced_stack_ref_callback
1903 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1904 jmethodID method, jlocation bci, jint slot, oop obj);
1905 static inline bool invoke_advanced_object_reference_callback
1906 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index);
1908 // used to report the value of primitive fields
1909 static inline bool report_primitive_field
1910 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type);
1912 public:
1913 // initialize for basic mode
1914 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1915 GrowableArray<oop>* visit_stack,
1916 const void* user_data,
1917 BasicHeapWalkContext context);
1919 // initialize for advanced mode
1920 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1921 GrowableArray<oop>* visit_stack,
1922 const void* user_data,
1923 AdvancedHeapWalkContext context);
1925 // functions to report roots
1926 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o);
1927 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1928 jmethodID m, oop o);
1929 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1930 jmethodID method, jlocation bci, jint slot, oop o);
1932 // functions to report references
1933 static inline bool report_array_element_reference(oop referrer, oop referree, jint index);
1934 static inline bool report_class_reference(oop referrer, oop referree);
1935 static inline bool report_class_loader_reference(oop referrer, oop referree);
1936 static inline bool report_signers_reference(oop referrer, oop referree);
1937 static inline bool report_protection_domain_reference(oop referrer, oop referree);
1938 static inline bool report_superclass_reference(oop referrer, oop referree);
1939 static inline bool report_interface_reference(oop referrer, oop referree);
1940 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot);
1941 static inline bool report_field_reference(oop referrer, oop referree, jint slot);
1942 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index);
1943 static inline bool report_primitive_array_values(oop array);
1944 static inline bool report_string_value(oop str);
1945 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type);
1946 static inline bool report_primitive_static_field(oop o, jint index, address value, char type);
1947 };
1949 // statics
1950 int CallbackInvoker::_heap_walk_type;
1951 BasicHeapWalkContext CallbackInvoker::_basic_context;
1952 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1953 JvmtiTagMap* CallbackInvoker::_tag_map;
1954 const void* CallbackInvoker::_user_data;
1955 GrowableArray<oop>* CallbackInvoker::_visit_stack;
1957 // initialize for basic heap walk (IterateOverReachableObjects et al)
1958 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1959 GrowableArray<oop>* visit_stack,
1960 const void* user_data,
1961 BasicHeapWalkContext context) {
1962 _tag_map = tag_map;
1963 _visit_stack = visit_stack;
1964 _user_data = user_data;
1965 _basic_context = context;
1966 _advanced_context.invalidate(); // will trigger assertion if used
1967 _heap_walk_type = basic;
1968 }
1970 // initialize for advanced heap walk (FollowReferences)
1971 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1972 GrowableArray<oop>* visit_stack,
1973 const void* user_data,
1974 AdvancedHeapWalkContext context) {
1975 _tag_map = tag_map;
1976 _visit_stack = visit_stack;
1977 _user_data = user_data;
1978 _advanced_context = context;
1979 _basic_context.invalidate(); // will trigger assertion if used
1980 _heap_walk_type = advanced;
1981 }
1984 // invoke basic style heap root callback
1985 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) {
1986 assert(ServiceUtil::visible_oop(obj), "checking");
1988 // if we heap roots should be reported
1989 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1990 if (cb == NULL) {
1991 return check_for_visit(obj);
1992 }
1994 CallbackWrapper wrapper(tag_map(), obj);
1995 jvmtiIterationControl control = (*cb)(root_kind,
1996 wrapper.klass_tag(),
1997 wrapper.obj_size(),
1998 wrapper.obj_tag_p(),
1999 (void*)user_data());
2000 // push root to visit stack when following references
2001 if (control == JVMTI_ITERATION_CONTINUE &&
2002 basic_context()->object_ref_callback() != NULL) {
2003 visit_stack()->push(obj);
2004 }
2005 return control != JVMTI_ITERATION_ABORT;
2006 }
2008 // invoke basic style stack ref callback
2009 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
2010 jlong thread_tag,
2011 jint depth,
2012 jmethodID method,
2013 jint slot,
2014 oop obj) {
2015 assert(ServiceUtil::visible_oop(obj), "checking");
2017 // if we stack refs should be reported
2018 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
2019 if (cb == NULL) {
2020 return check_for_visit(obj);
2021 }
2023 CallbackWrapper wrapper(tag_map(), obj);
2024 jvmtiIterationControl control = (*cb)(root_kind,
2025 wrapper.klass_tag(),
2026 wrapper.obj_size(),
2027 wrapper.obj_tag_p(),
2028 thread_tag,
2029 depth,
2030 method,
2031 slot,
2032 (void*)user_data());
2033 // push root to visit stack when following references
2034 if (control == JVMTI_ITERATION_CONTINUE &&
2035 basic_context()->object_ref_callback() != NULL) {
2036 visit_stack()->push(obj);
2037 }
2038 return control != JVMTI_ITERATION_ABORT;
2039 }
2041 // invoke basic style object reference callback
2042 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
2043 oop referrer,
2044 oop referree,
2045 jint index) {
2047 assert(ServiceUtil::visible_oop(referrer), "checking");
2048 assert(ServiceUtil::visible_oop(referree), "checking");
2050 BasicHeapWalkContext* context = basic_context();
2052 // callback requires the referrer's tag. If it's the same referrer
2053 // as the last call then we use the cached value.
2054 jlong referrer_tag;
2055 if (referrer == context->last_referrer()) {
2056 referrer_tag = context->last_referrer_tag();
2057 } else {
2058 referrer_tag = tag_for(tag_map(), klassOop_if_java_lang_Class(referrer));
2059 }
2061 // do the callback
2062 CallbackWrapper wrapper(tag_map(), referree);
2063 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2064 jvmtiIterationControl control = (*cb)(ref_kind,
2065 wrapper.klass_tag(),
2066 wrapper.obj_size(),
2067 wrapper.obj_tag_p(),
2068 referrer_tag,
2069 index,
2070 (void*)user_data());
2072 // record referrer and referrer tag. For self-references record the
2073 // tag value from the callback as this might differ from referrer_tag.
2074 context->set_last_referrer(referrer);
2075 if (referrer == referree) {
2076 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2077 } else {
2078 context->set_last_referrer_tag(referrer_tag);
2079 }
2081 if (control == JVMTI_ITERATION_CONTINUE) {
2082 return check_for_visit(referree);
2083 } else {
2084 return control != JVMTI_ITERATION_ABORT;
2085 }
2086 }
2088 // invoke advanced style heap root callback
2089 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2090 oop obj) {
2091 assert(ServiceUtil::visible_oop(obj), "checking");
2093 AdvancedHeapWalkContext* context = advanced_context();
2095 // check that callback is provided
2096 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2097 if (cb == NULL) {
2098 return check_for_visit(obj);
2099 }
2101 // apply class filter
2102 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2103 return check_for_visit(obj);
2104 }
2106 // setup the callback wrapper
2107 CallbackWrapper wrapper(tag_map(), obj);
2109 // apply tag filter
2110 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2111 wrapper.klass_tag(),
2112 context->heap_filter())) {
2113 return check_for_visit(obj);
2114 }
2116 // for arrays we need the length, otherwise -1
2117 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2119 // invoke the callback
2120 jint res = (*cb)(ref_kind,
2121 NULL, // referrer info
2122 wrapper.klass_tag(),
2123 0, // referrer_class_tag is 0 for heap root
2124 wrapper.obj_size(),
2125 wrapper.obj_tag_p(),
2126 NULL, // referrer_tag_p
2127 len,
2128 (void*)user_data());
2129 if (res & JVMTI_VISIT_ABORT) {
2130 return false;// referrer class tag
2131 }
2132 if (res & JVMTI_VISIT_OBJECTS) {
2133 check_for_visit(obj);
2134 }
2135 return true;
2136 }
2138 // report a reference from a thread stack to an object
2139 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2140 jlong thread_tag,
2141 jlong tid,
2142 int depth,
2143 jmethodID method,
2144 jlocation bci,
2145 jint slot,
2146 oop obj) {
2147 assert(ServiceUtil::visible_oop(obj), "checking");
2149 AdvancedHeapWalkContext* context = advanced_context();
2151 // check that callback is provider
2152 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2153 if (cb == NULL) {
2154 return check_for_visit(obj);
2155 }
2157 // apply class filter
2158 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2159 return check_for_visit(obj);
2160 }
2162 // setup the callback wrapper
2163 CallbackWrapper wrapper(tag_map(), obj);
2165 // apply tag filter
2166 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2167 wrapper.klass_tag(),
2168 context->heap_filter())) {
2169 return check_for_visit(obj);
2170 }
2172 // setup the referrer info
2173 jvmtiHeapReferenceInfo reference_info;
2174 reference_info.stack_local.thread_tag = thread_tag;
2175 reference_info.stack_local.thread_id = tid;
2176 reference_info.stack_local.depth = depth;
2177 reference_info.stack_local.method = method;
2178 reference_info.stack_local.location = bci;
2179 reference_info.stack_local.slot = slot;
2181 // for arrays we need the length, otherwise -1
2182 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2184 // call into the agent
2185 int res = (*cb)(ref_kind,
2186 &reference_info,
2187 wrapper.klass_tag(),
2188 0, // referrer_class_tag is 0 for heap root (stack)
2189 wrapper.obj_size(),
2190 wrapper.obj_tag_p(),
2191 NULL, // referrer_tag is 0 for root
2192 len,
2193 (void*)user_data());
2195 if (res & JVMTI_VISIT_ABORT) {
2196 return false;
2197 }
2198 if (res & JVMTI_VISIT_OBJECTS) {
2199 check_for_visit(obj);
2200 }
2201 return true;
2202 }
2204 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2205 // only for ref_kinds defined by the JVM TI spec. Otherwise, NULL is passed.
2206 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2207 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2208 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2209 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2210 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2211 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2213 // invoke the object reference callback to report a reference
2214 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2215 oop referrer,
2216 oop obj,
2217 jint index)
2218 {
2219 // field index is only valid field in reference_info
2220 static jvmtiHeapReferenceInfo reference_info = { 0 };
2222 assert(ServiceUtil::visible_oop(referrer), "checking");
2223 assert(ServiceUtil::visible_oop(obj), "checking");
2225 AdvancedHeapWalkContext* context = advanced_context();
2227 // check that callback is provider
2228 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2229 if (cb == NULL) {
2230 return check_for_visit(obj);
2231 }
2233 // apply class filter
2234 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2235 return check_for_visit(obj);
2236 }
2238 // setup the callback wrapper
2239 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2241 // apply tag filter
2242 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2243 wrapper.klass_tag(),
2244 context->heap_filter())) {
2245 return check_for_visit(obj);
2246 }
2248 // field index is only valid field in reference_info
2249 reference_info.field.index = index;
2251 // for arrays we need the length, otherwise -1
2252 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1);
2254 // invoke the callback
2255 int res = (*cb)(ref_kind,
2256 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : NULL,
2257 wrapper.klass_tag(),
2258 wrapper.referrer_klass_tag(),
2259 wrapper.obj_size(),
2260 wrapper.obj_tag_p(),
2261 wrapper.referrer_tag_p(),
2262 len,
2263 (void*)user_data());
2265 if (res & JVMTI_VISIT_ABORT) {
2266 return false;
2267 }
2268 if (res & JVMTI_VISIT_OBJECTS) {
2269 check_for_visit(obj);
2270 }
2271 return true;
2272 }
2274 // report a "simple root"
2275 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) {
2276 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2277 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2278 assert(ServiceUtil::visible_oop(obj), "checking");
2280 if (is_basic_heap_walk()) {
2281 // map to old style root kind
2282 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2283 return invoke_basic_heap_root_callback(root_kind, obj);
2284 } else {
2285 assert(is_advanced_heap_walk(), "wrong heap walk type");
2286 return invoke_advanced_heap_root_callback(kind, obj);
2287 }
2288 }
2291 // invoke the primitive array values
2292 inline bool CallbackInvoker::report_primitive_array_values(oop obj) {
2293 assert(obj->is_typeArray(), "not a primitive array");
2295 AdvancedHeapWalkContext* context = advanced_context();
2296 assert(context->array_primitive_value_callback() != NULL, "no callback");
2298 // apply class filter
2299 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2300 return true;
2301 }
2303 CallbackWrapper wrapper(tag_map(), obj);
2305 // apply tag filter
2306 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2307 wrapper.klass_tag(),
2308 context->heap_filter())) {
2309 return true;
2310 }
2312 // invoke the callback
2313 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2314 &wrapper,
2315 obj,
2316 (void*)user_data());
2317 return (!(res & JVMTI_VISIT_ABORT));
2318 }
2320 // invoke the string value callback
2321 inline bool CallbackInvoker::report_string_value(oop str) {
2322 assert(str->klass() == SystemDictionary::String_klass(), "not a string");
2324 AdvancedHeapWalkContext* context = advanced_context();
2325 assert(context->string_primitive_value_callback() != NULL, "no callback");
2327 // apply class filter
2328 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2329 return true;
2330 }
2332 CallbackWrapper wrapper(tag_map(), str);
2334 // apply tag filter
2335 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2336 wrapper.klass_tag(),
2337 context->heap_filter())) {
2338 return true;
2339 }
2341 // invoke the callback
2342 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2343 &wrapper,
2344 str,
2345 (void*)user_data());
2346 return (!(res & JVMTI_VISIT_ABORT));
2347 }
2349 // invoke the primitive field callback
2350 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2351 oop obj,
2352 jint index,
2353 address addr,
2354 char type)
2355 {
2356 // for primitive fields only the index will be set
2357 static jvmtiHeapReferenceInfo reference_info = { 0 };
2359 AdvancedHeapWalkContext* context = advanced_context();
2360 assert(context->primitive_field_callback() != NULL, "no callback");
2362 // apply class filter
2363 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2364 return true;
2365 }
2367 CallbackWrapper wrapper(tag_map(), obj);
2369 // apply tag filter
2370 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2371 wrapper.klass_tag(),
2372 context->heap_filter())) {
2373 return true;
2374 }
2376 // the field index in the referrer
2377 reference_info.field.index = index;
2379 // map the type
2380 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2382 // setup the jvalue
2383 jvalue value;
2384 copy_to_jvalue(&value, addr, value_type);
2386 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2387 int res = (*cb)(ref_kind,
2388 &reference_info,
2389 wrapper.klass_tag(),
2390 wrapper.obj_tag_p(),
2391 value,
2392 value_type,
2393 (void*)user_data());
2394 return (!(res & JVMTI_VISIT_ABORT));
2395 }
2398 // instance field
2399 inline bool CallbackInvoker::report_primitive_instance_field(oop obj,
2400 jint index,
2401 address value,
2402 char type) {
2403 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2404 obj,
2405 index,
2406 value,
2407 type);
2408 }
2410 // static field
2411 inline bool CallbackInvoker::report_primitive_static_field(oop obj,
2412 jint index,
2413 address value,
2414 char type) {
2415 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2416 obj,
2417 index,
2418 value,
2419 type);
2420 }
2422 // report a JNI local (root object) to the profiler
2423 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) {
2424 if (is_basic_heap_walk()) {
2425 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2426 thread_tag,
2427 depth,
2428 m,
2429 -1,
2430 obj);
2431 } else {
2432 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2433 thread_tag, tid,
2434 depth,
2435 m,
2436 (jlocation)-1,
2437 -1,
2438 obj);
2439 }
2440 }
2443 // report a local (stack reference, root object)
2444 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2445 jlong tid,
2446 jint depth,
2447 jmethodID method,
2448 jlocation bci,
2449 jint slot,
2450 oop obj) {
2451 if (is_basic_heap_walk()) {
2452 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2453 thread_tag,
2454 depth,
2455 method,
2456 slot,
2457 obj);
2458 } else {
2459 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2460 thread_tag,
2461 tid,
2462 depth,
2463 method,
2464 bci,
2465 slot,
2466 obj);
2467 }
2468 }
2470 // report an object referencing a class.
2471 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) {
2472 if (is_basic_heap_walk()) {
2473 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2474 } else {
2475 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2476 }
2477 }
2479 // report a class referencing its class loader.
2480 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) {
2481 if (is_basic_heap_walk()) {
2482 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2483 } else {
2484 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2485 }
2486 }
2488 // report a class referencing its signers.
2489 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) {
2490 if (is_basic_heap_walk()) {
2491 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2492 } else {
2493 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2494 }
2495 }
2497 // report a class referencing its protection domain..
2498 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) {
2499 if (is_basic_heap_walk()) {
2500 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2501 } else {
2502 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2503 }
2504 }
2506 // report a class referencing its superclass.
2507 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) {
2508 if (is_basic_heap_walk()) {
2509 // Send this to be consistent with past implementation
2510 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2511 } else {
2512 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2513 }
2514 }
2516 // report a class referencing one of its interfaces.
2517 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) {
2518 if (is_basic_heap_walk()) {
2519 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2520 } else {
2521 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2522 }
2523 }
2525 // report a class referencing one of its static fields.
2526 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) {
2527 if (is_basic_heap_walk()) {
2528 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2529 } else {
2530 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2531 }
2532 }
2534 // report an array referencing an element object
2535 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) {
2536 if (is_basic_heap_walk()) {
2537 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2538 } else {
2539 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2540 }
2541 }
2543 // report an object referencing an instance field object
2544 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) {
2545 if (is_basic_heap_walk()) {
2546 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2547 } else {
2548 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2549 }
2550 }
2552 // report an array referencing an element object
2553 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) {
2554 if (is_basic_heap_walk()) {
2555 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2556 } else {
2557 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2558 }
2559 }
2561 // A supporting closure used to process simple roots
2562 class SimpleRootsClosure : public OopClosure {
2563 private:
2564 jvmtiHeapReferenceKind _kind;
2565 bool _continue;
2567 jvmtiHeapReferenceKind root_kind() { return _kind; }
2569 public:
2570 void set_kind(jvmtiHeapReferenceKind kind) {
2571 _kind = kind;
2572 _continue = true;
2573 }
2575 inline bool stopped() {
2576 return !_continue;
2577 }
2579 void do_oop(oop* obj_p) {
2580 // iteration has terminated
2581 if (stopped()) {
2582 return;
2583 }
2585 // ignore null or deleted handles
2586 oop o = *obj_p;
2587 if (o == NULL || o == JNIHandles::deleted_handle()) {
2588 return;
2589 }
2591 jvmtiHeapReferenceKind kind = root_kind();
2593 // many roots are Klasses so we use the java mirror
2594 if (o->is_klass()) {
2595 klassOop k = (klassOop)o;
2596 o = Klass::cast(k)->java_mirror();
2597 } else {
2599 // SystemDictionary::always_strong_oops_do reports the application
2600 // class loader as a root. We want this root to be reported as
2601 // a root kind of "OTHER" rather than "SYSTEM_CLASS".
2602 if (o->is_instance() && root_kind() == JVMTI_HEAP_REFERENCE_SYSTEM_CLASS) {
2603 kind = JVMTI_HEAP_REFERENCE_OTHER;
2604 }
2605 }
2607 // some objects are ignored - in the case of simple
2608 // roots it's mostly Symbol*s that we are skipping
2609 // here.
2610 if (!ServiceUtil::visible_oop(o)) {
2611 return;
2612 }
2614 // invoke the callback
2615 _continue = CallbackInvoker::report_simple_root(kind, o);
2617 }
2618 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2619 };
2621 // A supporting closure used to process JNI locals
2622 class JNILocalRootsClosure : public OopClosure {
2623 private:
2624 jlong _thread_tag;
2625 jlong _tid;
2626 jint _depth;
2627 jmethodID _method;
2628 bool _continue;
2629 public:
2630 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2631 _thread_tag = thread_tag;
2632 _tid = tid;
2633 _depth = depth;
2634 _method = method;
2635 _continue = true;
2636 }
2638 inline bool stopped() {
2639 return !_continue;
2640 }
2642 void do_oop(oop* obj_p) {
2643 // iteration has terminated
2644 if (stopped()) {
2645 return;
2646 }
2648 // ignore null or deleted handles
2649 oop o = *obj_p;
2650 if (o == NULL || o == JNIHandles::deleted_handle()) {
2651 return;
2652 }
2654 if (!ServiceUtil::visible_oop(o)) {
2655 return;
2656 }
2658 // invoke the callback
2659 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2660 }
2661 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2662 };
2665 // A VM operation to iterate over objects that are reachable from
2666 // a set of roots or an initial object.
2667 //
2668 // For VM_HeapWalkOperation the set of roots used is :-
2669 //
2670 // - All JNI global references
2671 // - All inflated monitors
2672 // - All classes loaded by the boot class loader (or all classes
2673 // in the event that class unloading is disabled)
2674 // - All java threads
2675 // - For each java thread then all locals and JNI local references
2676 // on the thread's execution stack
2677 // - All visible/explainable objects from Universes::oops_do
2678 //
2679 class VM_HeapWalkOperation: public VM_Operation {
2680 private:
2681 enum {
2682 initial_visit_stack_size = 4000
2683 };
2685 bool _is_advanced_heap_walk; // indicates FollowReferences
2686 JvmtiTagMap* _tag_map;
2687 Handle _initial_object;
2688 GrowableArray<oop>* _visit_stack; // the visit stack
2690 bool _collecting_heap_roots; // are we collecting roots
2691 bool _following_object_refs; // are we following object references
2693 bool _reporting_primitive_fields; // optional reporting
2694 bool _reporting_primitive_array_values;
2695 bool _reporting_string_values;
2697 GrowableArray<oop>* create_visit_stack() {
2698 return new (ResourceObj::C_HEAP) GrowableArray<oop>(initial_visit_stack_size, true);
2699 }
2701 // accessors
2702 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2703 JvmtiTagMap* tag_map() const { return _tag_map; }
2704 Handle initial_object() const { return _initial_object; }
2706 bool is_following_references() const { return _following_object_refs; }
2708 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2709 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2710 bool is_reporting_string_values() const { return _reporting_string_values; }
2712 GrowableArray<oop>* visit_stack() const { return _visit_stack; }
2714 // iterate over the various object types
2715 inline bool iterate_over_array(oop o);
2716 inline bool iterate_over_type_array(oop o);
2717 inline bool iterate_over_class(klassOop o);
2718 inline bool iterate_over_object(oop o);
2720 // root collection
2721 inline bool collect_simple_roots();
2722 inline bool collect_stack_roots();
2723 inline bool collect_stack_roots(JavaThread* java_thread, JNILocalRootsClosure* blk);
2725 // visit an object
2726 inline bool visit(oop o);
2728 public:
2729 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2730 Handle initial_object,
2731 BasicHeapWalkContext callbacks,
2732 const void* user_data);
2734 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2735 Handle initial_object,
2736 AdvancedHeapWalkContext callbacks,
2737 const void* user_data);
2739 ~VM_HeapWalkOperation();
2741 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2742 void doit();
2743 };
2746 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2747 Handle initial_object,
2748 BasicHeapWalkContext callbacks,
2749 const void* user_data) {
2750 _is_advanced_heap_walk = false;
2751 _tag_map = tag_map;
2752 _initial_object = initial_object;
2753 _following_object_refs = (callbacks.object_ref_callback() != NULL);
2754 _reporting_primitive_fields = false;
2755 _reporting_primitive_array_values = false;
2756 _reporting_string_values = false;
2757 _visit_stack = create_visit_stack();
2760 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2761 }
2763 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2764 Handle initial_object,
2765 AdvancedHeapWalkContext callbacks,
2766 const void* user_data) {
2767 _is_advanced_heap_walk = true;
2768 _tag_map = tag_map;
2769 _initial_object = initial_object;
2770 _following_object_refs = true;
2771 _reporting_primitive_fields = (callbacks.primitive_field_callback() != NULL);;
2772 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != NULL);;
2773 _reporting_string_values = (callbacks.string_primitive_value_callback() != NULL);;
2774 _visit_stack = create_visit_stack();
2776 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks);
2777 }
2779 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2780 if (_following_object_refs) {
2781 assert(_visit_stack != NULL, "checking");
2782 delete _visit_stack;
2783 _visit_stack = NULL;
2784 }
2785 }
2787 // an array references its class and has a reference to
2788 // each element in the array
2789 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) {
2790 objArrayOop array = objArrayOop(o);
2791 if (array->klass() == Universe::systemObjArrayKlassObj()) {
2792 // filtered out
2793 return true;
2794 }
2796 // array reference to its class
2797 oop mirror = objArrayKlass::cast(array->klass())->java_mirror();
2798 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2799 return false;
2800 }
2802 // iterate over the array and report each reference to a
2803 // non-null element
2804 for (int index=0; index<array->length(); index++) {
2805 oop elem = array->obj_at(index);
2806 if (elem == NULL) {
2807 continue;
2808 }
2810 // report the array reference o[index] = elem
2811 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2812 return false;
2813 }
2814 }
2815 return true;
2816 }
2818 // a type array references its class
2819 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) {
2820 klassOop k = o->klass();
2821 oop mirror = Klass::cast(k)->java_mirror();
2822 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2823 return false;
2824 }
2826 // report the array contents if required
2827 if (is_reporting_primitive_array_values()) {
2828 if (!CallbackInvoker::report_primitive_array_values(o)) {
2829 return false;
2830 }
2831 }
2832 return true;
2833 }
2835 // verify that a static oop field is in range
2836 static inline bool verify_static_oop(instanceKlass* ik,
2837 klassOop k, int offset) {
2838 address obj_p = (address)k + offset;
2839 address start = (address)ik->start_of_static_fields();
2840 address end = start + (ik->static_oop_field_size() * heapOopSize);
2841 assert(end >= start, "sanity check");
2843 if (obj_p >= start && obj_p < end) {
2844 return true;
2845 } else {
2846 return false;
2847 }
2848 }
2850 // a class references its super class, interfaces, class loader, ...
2851 // and finally its static fields
2852 inline bool VM_HeapWalkOperation::iterate_over_class(klassOop k) {
2853 int i;
2854 Klass* klass = klassOop(k)->klass_part();
2856 if (klass->oop_is_instance()) {
2857 instanceKlass* ik = instanceKlass::cast(k);
2859 // ignore the class if it's has been initialized yet
2860 if (!ik->is_linked()) {
2861 return true;
2862 }
2864 // get the java mirror
2865 oop mirror = klass->java_mirror();
2867 // super (only if something more interesting than java.lang.Object)
2868 klassOop java_super = ik->java_super();
2869 if (java_super != NULL && java_super != SystemDictionary::Object_klass()) {
2870 oop super = Klass::cast(java_super)->java_mirror();
2871 if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2872 return false;
2873 }
2874 }
2876 // class loader
2877 oop cl = ik->class_loader();
2878 if (cl != NULL) {
2879 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2880 return false;
2881 }
2882 }
2884 // protection domain
2885 oop pd = ik->protection_domain();
2886 if (pd != NULL) {
2887 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2888 return false;
2889 }
2890 }
2892 // signers
2893 oop signers = ik->signers();
2894 if (signers != NULL) {
2895 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2896 return false;
2897 }
2898 }
2900 // references from the constant pool
2901 {
2902 const constantPoolOop pool = ik->constants();
2903 for (int i = 1; i < pool->length(); i++) {
2904 constantTag tag = pool->tag_at(i).value();
2905 if (tag.is_string() || tag.is_klass()) {
2906 oop entry;
2907 if (tag.is_string()) {
2908 entry = pool->resolved_string_at(i);
2909 assert(java_lang_String::is_instance(entry), "must be string");
2910 } else {
2911 entry = Klass::cast(pool->resolved_klass_at(i))->java_mirror();
2912 }
2913 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
2914 return false;
2915 }
2916 }
2917 }
2918 }
2920 // interfaces
2921 // (These will already have been reported as references from the constant pool
2922 // but are specified by IterateOverReachableObjects and must be reported).
2923 objArrayOop interfaces = ik->local_interfaces();
2924 for (i = 0; i < interfaces->length(); i++) {
2925 oop interf = Klass::cast((klassOop)interfaces->obj_at(i))->java_mirror();
2926 if (interf == NULL) {
2927 continue;
2928 }
2929 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
2930 return false;
2931 }
2932 }
2934 // iterate over the static fields
2936 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(k);
2937 for (i=0; i<field_map->field_count(); i++) {
2938 ClassFieldDescriptor* field = field_map->field_at(i);
2939 char type = field->field_type();
2940 if (!is_primitive_field_type(type)) {
2941 oop fld_o = k->obj_field(field->field_offset());
2942 assert(verify_static_oop(ik, k, field->field_offset()), "sanity check");
2943 if (fld_o != NULL) {
2944 int slot = field->field_index();
2945 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
2946 delete field_map;
2947 return false;
2948 }
2949 }
2950 } else {
2951 if (is_reporting_primitive_fields()) {
2952 address addr = (address)k + field->field_offset();
2953 int slot = field->field_index();
2954 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
2955 delete field_map;
2956 return false;
2957 }
2958 }
2959 }
2960 }
2961 delete field_map;
2963 return true;
2964 }
2966 return true;
2967 }
2969 // an object references a class and its instance fields
2970 // (static fields are ignored here as we report these as
2971 // references from the class).
2972 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) {
2973 // reference to the class
2974 if (!CallbackInvoker::report_class_reference(o, Klass::cast(o->klass())->java_mirror())) {
2975 return false;
2976 }
2978 // iterate over instance fields
2979 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o);
2980 for (int i=0; i<field_map->field_count(); i++) {
2981 ClassFieldDescriptor* field = field_map->field_at(i);
2982 char type = field->field_type();
2983 if (!is_primitive_field_type(type)) {
2984 oop fld_o = o->obj_field(field->field_offset());
2985 if (fld_o != NULL) {
2986 // reflection code may have a reference to a klassOop.
2987 // - see sun.reflect.UnsafeStaticFieldAccessorImpl and sun.misc.Unsafe
2988 if (fld_o->is_klass()) {
2989 klassOop k = (klassOop)fld_o;
2990 fld_o = Klass::cast(k)->java_mirror();
2991 }
2992 int slot = field->field_index();
2993 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
2994 return false;
2995 }
2996 }
2997 } else {
2998 if (is_reporting_primitive_fields()) {
2999 // primitive instance field
3000 address addr = (address)o + field->field_offset();
3001 int slot = field->field_index();
3002 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
3003 return false;
3004 }
3005 }
3006 }
3007 }
3009 // if the object is a java.lang.String
3010 if (is_reporting_string_values() &&
3011 o->klass() == SystemDictionary::String_klass()) {
3012 if (!CallbackInvoker::report_string_value(o)) {
3013 return false;
3014 }
3015 }
3016 return true;
3017 }
3020 // collects all simple (non-stack) roots.
3021 // if there's a heap root callback provided then the callback is
3022 // invoked for each simple root.
3023 // if an object reference callback is provided then all simple
3024 // roots are pushed onto the marking stack so that they can be
3025 // processed later
3026 //
3027 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3028 SimpleRootsClosure blk;
3030 // JNI globals
3031 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3032 JNIHandles::oops_do(&blk);
3033 if (blk.stopped()) {
3034 return false;
3035 }
3037 // Preloaded classes and loader from the system dictionary
3038 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3039 SystemDictionary::always_strong_oops_do(&blk);
3040 if (blk.stopped()) {
3041 return false;
3042 }
3044 // Inflated monitors
3045 blk.set_kind(JVMTI_HEAP_REFERENCE_MONITOR);
3046 ObjectSynchronizer::oops_do(&blk);
3047 if (blk.stopped()) {
3048 return false;
3049 }
3051 // Threads
3052 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3053 oop threadObj = thread->threadObj();
3054 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3055 bool cont = CallbackInvoker::report_simple_root(JVMTI_HEAP_REFERENCE_THREAD, threadObj);
3056 if (!cont) {
3057 return false;
3058 }
3059 }
3060 }
3062 // Other kinds of roots maintained by HotSpot
3063 // Many of these won't be visible but others (such as instances of important
3064 // exceptions) will be visible.
3065 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3066 Universe::oops_do(&blk);
3068 // If there are any non-perm roots in the code cache, visit them.
3069 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3070 CodeBlobToOopClosure look_in_blobs(&blk, false);
3071 CodeCache::scavenge_root_nmethods_do(&look_in_blobs);
3073 return true;
3074 }
3076 // Walk the stack of a given thread and find all references (locals
3077 // and JNI calls) and report these as stack references
3078 inline bool VM_HeapWalkOperation::collect_stack_roots(JavaThread* java_thread,
3079 JNILocalRootsClosure* blk)
3080 {
3081 oop threadObj = java_thread->threadObj();
3082 assert(threadObj != NULL, "sanity check");
3084 // only need to get the thread's tag once per thread
3085 jlong thread_tag = tag_for(_tag_map, threadObj);
3087 // also need the thread id
3088 jlong tid = java_lang_Thread::thread_id(threadObj);
3091 if (java_thread->has_last_Java_frame()) {
3093 // vframes are resource allocated
3094 Thread* current_thread = Thread::current();
3095 ResourceMark rm(current_thread);
3096 HandleMark hm(current_thread);
3098 RegisterMap reg_map(java_thread);
3099 frame f = java_thread->last_frame();
3100 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3102 bool is_top_frame = true;
3103 int depth = 0;
3104 frame* last_entry_frame = NULL;
3106 while (vf != NULL) {
3107 if (vf->is_java_frame()) {
3109 // java frame (interpreted, compiled, ...)
3110 javaVFrame *jvf = javaVFrame::cast(vf);
3112 // the jmethodID
3113 jmethodID method = jvf->method()->jmethod_id();
3115 if (!(jvf->method()->is_native())) {
3116 jlocation bci = (jlocation)jvf->bci();
3117 StackValueCollection* locals = jvf->locals();
3118 for (int slot=0; slot<locals->size(); slot++) {
3119 if (locals->at(slot)->type() == T_OBJECT) {
3120 oop o = locals->obj_at(slot)();
3121 if (o == NULL) {
3122 continue;
3123 }
3125 // stack reference
3126 if (!CallbackInvoker::report_stack_ref_root(thread_tag, tid, depth, method,
3127 bci, slot, o)) {
3128 return false;
3129 }
3130 }
3131 }
3132 } else {
3133 blk->set_context(thread_tag, tid, depth, method);
3134 if (is_top_frame) {
3135 // JNI locals for the top frame.
3136 java_thread->active_handles()->oops_do(blk);
3137 } else {
3138 if (last_entry_frame != NULL) {
3139 // JNI locals for the entry frame
3140 assert(last_entry_frame->is_entry_frame(), "checking");
3141 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(blk);
3142 }
3143 }
3144 }
3145 last_entry_frame = NULL;
3146 depth++;
3147 } else {
3148 // externalVFrame - for an entry frame then we report the JNI locals
3149 // when we find the corresponding javaVFrame
3150 frame* fr = vf->frame_pointer();
3151 assert(fr != NULL, "sanity check");
3152 if (fr->is_entry_frame()) {
3153 last_entry_frame = fr;
3154 }
3155 }
3157 vf = vf->sender();
3158 is_top_frame = false;
3159 }
3160 } else {
3161 // no last java frame but there may be JNI locals
3162 blk->set_context(thread_tag, tid, 0, (jmethodID)NULL);
3163 java_thread->active_handles()->oops_do(blk);
3164 }
3165 return true;
3166 }
3169 // collects all stack roots - for each thread it walks the execution
3170 // stack to find all references and local JNI refs.
3171 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3172 JNILocalRootsClosure blk;
3173 for (JavaThread* thread = Threads::first(); thread != NULL ; thread = thread->next()) {
3174 oop threadObj = thread->threadObj();
3175 if (threadObj != NULL && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3176 if (!collect_stack_roots(thread, &blk)) {
3177 return false;
3178 }
3179 }
3180 }
3181 return true;
3182 }
3184 // visit an object
3185 // first mark the object as visited
3186 // second get all the outbound references from this object (in other words, all
3187 // the objects referenced by this object).
3188 //
3189 bool VM_HeapWalkOperation::visit(oop o) {
3190 // mark object as visited
3191 assert(!ObjectMarker::visited(o), "can't visit same object more than once");
3192 ObjectMarker::mark(o);
3194 // instance
3195 if (o->is_instance()) {
3196 if (o->klass() == SystemDictionary::Class_klass()) {
3197 o = klassOop_if_java_lang_Class(o);
3198 if (o->is_klass()) {
3199 // a java.lang.Class
3200 return iterate_over_class(klassOop(o));
3201 }
3202 } else {
3203 return iterate_over_object(o);
3204 }
3205 }
3207 // object array
3208 if (o->is_objArray()) {
3209 return iterate_over_array(o);
3210 }
3212 // type array
3213 if (o->is_typeArray()) {
3214 return iterate_over_type_array(o);
3215 }
3217 return true;
3218 }
3220 void VM_HeapWalkOperation::doit() {
3221 ResourceMark rm;
3222 ObjectMarkerController marker;
3223 ClassFieldMapCacheMark cm;
3225 assert(visit_stack()->is_empty(), "visit stack must be empty");
3227 // the heap walk starts with an initial object or the heap roots
3228 if (initial_object().is_null()) {
3229 if (!collect_simple_roots()) return;
3230 if (!collect_stack_roots()) return;
3231 } else {
3232 visit_stack()->push(initial_object()());
3233 }
3235 // object references required
3236 if (is_following_references()) {
3238 // visit each object until all reachable objects have been
3239 // visited or the callback asked to terminate the iteration.
3240 while (!visit_stack()->is_empty()) {
3241 oop o = visit_stack()->pop();
3242 if (!ObjectMarker::visited(o)) {
3243 if (!visit(o)) {
3244 break;
3245 }
3246 }
3247 }
3248 }
3249 }
3251 // iterate over all objects that are reachable from a set of roots
3252 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3253 jvmtiStackReferenceCallback stack_ref_callback,
3254 jvmtiObjectReferenceCallback object_ref_callback,
3255 const void* user_data) {
3256 MutexLocker ml(Heap_lock);
3257 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3258 VM_HeapWalkOperation op(this, Handle(), context, user_data);
3259 VMThread::execute(&op);
3260 }
3262 // iterate over all objects that are reachable from a given object
3263 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3264 jvmtiObjectReferenceCallback object_ref_callback,
3265 const void* user_data) {
3266 oop obj = JNIHandles::resolve(object);
3267 Handle initial_object(Thread::current(), obj);
3269 MutexLocker ml(Heap_lock);
3270 BasicHeapWalkContext context(NULL, NULL, object_ref_callback);
3271 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3272 VMThread::execute(&op);
3273 }
3275 // follow references from an initial object or the GC roots
3276 void JvmtiTagMap::follow_references(jint heap_filter,
3277 KlassHandle klass,
3278 jobject object,
3279 const jvmtiHeapCallbacks* callbacks,
3280 const void* user_data)
3281 {
3282 oop obj = JNIHandles::resolve(object);
3283 Handle initial_object(Thread::current(), obj);
3285 MutexLocker ml(Heap_lock);
3286 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3287 VM_HeapWalkOperation op(this, initial_object, context, user_data);
3288 VMThread::execute(&op);
3289 }
3292 void JvmtiTagMap::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
3293 // No locks during VM bring-up (0 threads) and no safepoints after main
3294 // thread creation and before VMThread creation (1 thread); initial GC
3295 // verification can happen in that window which gets to here.
3296 assert(Threads::number_of_threads() <= 1 ||
3297 SafepointSynchronize::is_at_safepoint(),
3298 "must be executed at a safepoint");
3299 if (JvmtiEnv::environments_might_exist()) {
3300 JvmtiEnvIterator it;
3301 for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
3302 JvmtiTagMap* tag_map = env->tag_map();
3303 if (tag_map != NULL && !tag_map->is_empty()) {
3304 tag_map->do_weak_oops(is_alive, f);
3305 }
3306 }
3307 }
3308 }
3310 void JvmtiTagMap::do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f) {
3312 // does this environment have the OBJECT_FREE event enabled
3313 bool post_object_free = env()->is_enabled(JVMTI_EVENT_OBJECT_FREE);
3315 // counters used for trace message
3316 int freed = 0;
3317 int moved = 0;
3319 JvmtiTagHashmap* hashmap = this->hashmap();
3321 // reenable sizing (if disabled)
3322 hashmap->set_resizing_enabled(true);
3324 // if the hashmap is empty then we can skip it
3325 if (hashmap->_entry_count == 0) {
3326 return;
3327 }
3329 // now iterate through each entry in the table
3331 JvmtiTagHashmapEntry** table = hashmap->table();
3332 int size = hashmap->size();
3334 JvmtiTagHashmapEntry* delayed_add = NULL;
3336 for (int pos = 0; pos < size; ++pos) {
3337 JvmtiTagHashmapEntry* entry = table[pos];
3338 JvmtiTagHashmapEntry* prev = NULL;
3340 while (entry != NULL) {
3341 JvmtiTagHashmapEntry* next = entry->next();
3343 oop* obj = entry->object_addr();
3345 // has object been GC'ed
3346 if (!is_alive->do_object_b(entry->object())) {
3347 // grab the tag
3348 jlong tag = entry->tag();
3349 guarantee(tag != 0, "checking");
3351 // remove GC'ed entry from hashmap and return the
3352 // entry to the free list
3353 hashmap->remove(prev, pos, entry);
3354 destroy_entry(entry);
3356 // post the event to the profiler
3357 if (post_object_free) {
3358 JvmtiExport::post_object_free(env(), tag);
3359 }
3361 ++freed;
3362 } else {
3363 f->do_oop(entry->object_addr());
3364 oop new_oop = entry->object();
3366 // if the object has moved then re-hash it and move its
3367 // entry to its new location.
3368 unsigned int new_pos = JvmtiTagHashmap::hash(new_oop, size);
3369 if (new_pos != (unsigned int)pos) {
3370 if (prev == NULL) {
3371 table[pos] = next;
3372 } else {
3373 prev->set_next(next);
3374 }
3375 if (new_pos < (unsigned int)pos) {
3376 entry->set_next(table[new_pos]);
3377 table[new_pos] = entry;
3378 } else {
3379 // Delay adding this entry to it's new position as we'd end up
3380 // hitting it again during this iteration.
3381 entry->set_next(delayed_add);
3382 delayed_add = entry;
3383 }
3384 moved++;
3385 } else {
3386 // object didn't move
3387 prev = entry;
3388 }
3389 }
3391 entry = next;
3392 }
3393 }
3395 // Re-add all the entries which were kept aside
3396 while (delayed_add != NULL) {
3397 JvmtiTagHashmapEntry* next = delayed_add->next();
3398 unsigned int pos = JvmtiTagHashmap::hash(delayed_add->object(), size);
3399 delayed_add->set_next(table[pos]);
3400 table[pos] = delayed_add;
3401 delayed_add = next;
3402 }
3404 // stats
3405 if (TraceJVMTIObjectTagging) {
3406 int post_total = hashmap->_entry_count;
3407 int pre_total = post_total + freed;
3409 tty->print_cr("(%d->%d, %d freed, %d total moves)",
3410 pre_total, post_total, freed, moved);
3411 }
3412 }