1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/altHashing.hpp"
27 #include "classfile/compactHashtable.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/stringTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "gc/shared/collectedHeap.hpp"
32 #include "gc/shared/oopStorage.inline.hpp"
33 #include "gc/shared/oopStorageParState.inline.hpp"
34 #include "logging/log.hpp"
35 #include "logging/logStream.hpp"
36 #include "memory/allocation.inline.hpp"
37 #include "memory/filemap.hpp"
38 #include "memory/heapShared.inline.hpp"
39 #include "memory/metaspaceShared.inline.hpp"
40 #include "memory/resourceArea.hpp"
41 #include "memory/universe.hpp"
42 #include "oops/access.inline.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "oops/typeArrayOop.inline.hpp"
45 #include "oops/weakHandle.inline.hpp"
46 #include "runtime/atomic.hpp"
47 #include "runtime/handles.inline.hpp"
48 #include "runtime/mutexLocker.hpp"
49 #include "runtime/safepointVerifiers.hpp"
50 #include "runtime/timerTrace.hpp"
51 #include "runtime/interfaceSupport.inline.hpp"
52 #include "services/diagnosticCommand.hpp"
53 #include "utilities/concurrentHashTable.inline.hpp"
54 #include "utilities/concurrentHashTableTasks.inline.hpp"
55 #include "utilities/macros.hpp"
56
57 // We prefer short chains of avg 2
58 #define PREF_AVG_LIST_LEN 2
59 // 2^24 is max size
60 #define END_SIZE 24
61 // If a chain gets to 32 something might be wrong
62 #define REHASH_LEN 32
63 // If we have as many dead items as 50% of the number of bucket
64 #define CLEAN_DEAD_HIGH_WATER_MARK 0.5
65
66 #if INCLUDE_CDS_JAVA_HEAP
67 inline oop read_string_from_compact_hashtable(address base_address, u4 offset) {
68 assert(sizeof(narrowOop) == sizeof(offset), "must be");
69 narrowOop v = (narrowOop)offset;
70 return HeapShared::decode_from_archive(v);
71 }
72
73 static CompactHashtable<
74 const jchar*, oop,
75 read_string_from_compact_hashtable,
76 java_lang_String::equals
77 > _shared_table;
78 #endif
79
80 // --------------------------------------------------------------------------
81 StringTable* StringTable::_the_table = NULL;
82 volatile bool StringTable::_shared_string_mapped = false;
83 volatile bool StringTable::_alt_hash = false;
84
85 static juint murmur_seed = 0;
86
87 uintx hash_string(const jchar* s, int len, bool useAlt) {
88 return useAlt ?
89 AltHashing::murmur3_32(murmur_seed, s, len) :
90 java_lang_String::hash_code(s, len);
91 }
92
93 class StringTableConfig : public StringTableHash::BaseConfig {
94 private:
95 public:
96 static uintx get_hash(WeakHandle<vm_string_table_data> const& value,
97 bool* is_dead) {
98 EXCEPTION_MARK;
99 oop val_oop = value.peek();
100 if (val_oop == NULL) {
101 *is_dead = true;
102 return 0;
103 }
104 *is_dead = false;
105 ResourceMark rm(THREAD);
106 // All String oops are hashed as unicode
107 int length;
108 jchar* chars = java_lang_String::as_unicode_string(val_oop, length, THREAD);
109 if (chars != NULL) {
110 return hash_string(chars, length, StringTable::_alt_hash);
111 }
112 vm_exit_out_of_memory(length, OOM_MALLOC_ERROR, "get hash from oop");
113 return 0;
114 }
115 // We use default allocation/deallocation but counted
116 static void* allocate_node(size_t size,
117 WeakHandle<vm_string_table_data> const& value) {
118 StringTable::item_added();
119 return StringTableHash::BaseConfig::allocate_node(size, value);
120 }
121 static void free_node(void* memory,
122 WeakHandle<vm_string_table_data> const& value) {
123 value.release();
124 StringTableHash::BaseConfig::free_node(memory, value);
125 StringTable::item_removed();
126 }
127 };
128
129 class StringTableLookupJchar : StackObj {
130 private:
131 Thread* _thread;
132 uintx _hash;
133 int _len;
134 const jchar* _str;
135 Handle _found;
136
137 public:
138 StringTableLookupJchar(Thread* thread, uintx hash, const jchar* key, int len)
139 : _thread(thread), _hash(hash), _len(len), _str(key) {
140 }
141 uintx get_hash() const {
142 return _hash;
143 }
144 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
145 oop val_oop = value->peek();
146 if (val_oop == NULL) {
147 // dead oop, mark this hash dead for cleaning
148 *is_dead = true;
149 return false;
150 }
151 bool equals = java_lang_String::equals(val_oop, _str, _len);
152 if (!equals) {
153 return false;
154 }
155 // Need to resolve weak handle and Handleize through possible safepoint.
156 _found = Handle(_thread, value->resolve());
157 return true;
158 }
159 };
160
161 class StringTableLookupOop : public StackObj {
162 private:
163 Thread* _thread;
164 uintx _hash;
165 Handle _find;
166 Handle _found; // Might be a different oop with the same value that's already
167 // in the table, which is the point.
168 public:
169 StringTableLookupOop(Thread* thread, uintx hash, Handle handle)
170 : _thread(thread), _hash(hash), _find(handle) { }
171
172 uintx get_hash() const {
173 return _hash;
174 }
175
176 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
177 oop val_oop = value->peek();
178 if (val_oop == NULL) {
179 // dead oop, mark this hash dead for cleaning
180 *is_dead = true;
181 return false;
182 }
183 bool equals = java_lang_String::equals(_find(), val_oop);
184 if (!equals) {
185 return false;
186 }
187 // Need to resolve weak handle and Handleize through possible safepoint.
188 _found = Handle(_thread, value->resolve());
189 return true;
190 }
191 };
192
193 static size_t ceil_log2(size_t val) {
194 size_t ret;
195 for (ret = 1; ((size_t)1 << ret) < val; ++ret);
196 return ret;
197 }
198
199 StringTable::StringTable() : _local_table(NULL), _current_size(0), _has_work(0),
200 _needs_rehashing(false), _weak_handles(NULL), _items_count(0), _uncleaned_items_count(0) {
201 _weak_handles = new OopStorage("StringTable weak",
202 StringTableWeakAlloc_lock,
203 StringTableWeakActive_lock);
204 size_t start_size_log_2 = ceil_log2(StringTableSize);
205 _current_size = ((size_t)1) << start_size_log_2;
206 log_trace(stringtable)("Start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
207 _current_size, start_size_log_2);
208 _local_table = new StringTableHash(start_size_log_2, END_SIZE, REHASH_LEN);
209 }
210
211 size_t StringTable::item_added() {
212 return Atomic::add((size_t)1, &(the_table()->_items_count));
213 }
214
215 size_t StringTable::add_items_count_to_clean(size_t ndead) {
216 size_t total = Atomic::add((size_t)ndead, &(the_table()->_uncleaned_items_count));
217 log_trace(stringtable)(
218 "Uncleaned items:" SIZE_FORMAT " added: " SIZE_FORMAT " total:" SIZE_FORMAT,
219 the_table()->_uncleaned_items_count, ndead, total);
220 return total;
221 }
222
223 void StringTable::item_removed() {
224 Atomic::add((size_t)-1, &(the_table()->_items_count));
225 }
226
227 double StringTable::get_load_factor() {
228 return (double)_items_count/_current_size;
229 }
230
231 double StringTable::get_dead_factor() {
232 return (double)_uncleaned_items_count/_current_size;
233 }
234
235 size_t StringTable::table_size() {
236 return ((size_t)1) << _local_table->get_size_log2(Thread::current());
237 }
238
239 void StringTable::trigger_concurrent_work() {
240 MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
241 the_table()->_has_work = true;
242 Service_lock->notify_all();
243 }
244
245 // Probing
246 oop StringTable::lookup(Symbol* symbol) {
247 ResourceMark rm;
248 int length;
249 jchar* chars = symbol->as_unicode(length);
250 return lookup(chars, length);
251 }
252
253 oop StringTable::lookup(const jchar* name, int len) {
254 unsigned int hash = java_lang_String::hash_code(name, len);
255 oop string = StringTable::the_table()->lookup_shared(name, len, hash);
256 if (string != NULL) {
257 return string;
258 }
259 if (StringTable::_alt_hash) {
260 hash = hash_string(name, len, true);
261 }
262 return StringTable::the_table()->do_lookup(name, len, hash);
263 }
264
265 class StringTableGet : public StackObj {
266 Thread* _thread;
267 Handle _return;
268 public:
269 StringTableGet(Thread* thread) : _thread(thread) {}
270 void operator()(WeakHandle<vm_string_table_data>* val) {
271 oop result = val->resolve();
272 assert(result != NULL, "Result should be reachable");
273 _return = Handle(_thread, result);
274 }
275 oop get_res_oop() {
276 return _return();
277 }
278 };
279
280 oop StringTable::do_lookup(const jchar* name, int len, uintx hash) {
281 Thread* thread = Thread::current();
282 StringTableLookupJchar lookup(thread, hash, name, len);
283 StringTableGet stg(thread);
284 bool rehash_warning;
285 _local_table->get(thread, lookup, stg, &rehash_warning);
286 if (rehash_warning) {
287 _needs_rehashing = true;
288 }
289 return stg.get_res_oop();
290 }
291
292 // Interning
293 oop StringTable::intern(Symbol* symbol, TRAPS) {
294 if (symbol == NULL) return NULL;
295 ResourceMark rm(THREAD);
296 int length;
297 jchar* chars = symbol->as_unicode(length);
298 Handle string;
299 oop result = intern(string, chars, length, CHECK_NULL);
300 return result;
301 }
302
303 oop StringTable::intern(oop string, TRAPS) {
304 if (string == NULL) return NULL;
305 ResourceMark rm(THREAD);
306 int length;
307 Handle h_string (THREAD, string);
308 jchar* chars = java_lang_String::as_unicode_string(string, length,
309 CHECK_NULL);
310 oop result = intern(h_string, chars, length, CHECK_NULL);
311 return result;
312 }
313
314 oop StringTable::intern(const char* utf8_string, TRAPS) {
315 if (utf8_string == NULL) return NULL;
316 ResourceMark rm(THREAD);
317 int length = UTF8::unicode_length(utf8_string);
318 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
319 UTF8::convert_to_unicode(utf8_string, chars, length);
320 Handle string;
321 oop result = intern(string, chars, length, CHECK_NULL);
322 return result;
323 }
324
325 oop StringTable::intern(Handle string_or_null_h, const jchar* name, int len, TRAPS) {
326 // shared table always uses java_lang_String::hash_code
327 unsigned int hash = java_lang_String::hash_code(name, len);
328 oop found_string = StringTable::the_table()->lookup_shared(name, len, hash);
329 if (found_string != NULL) {
330 return found_string;
331 }
332 if (StringTable::_alt_hash) {
333 hash = hash_string(name, len, true);
334 }
335 return StringTable::the_table()->do_intern(string_or_null_h, name, len,
336 hash, CHECK_NULL);
337 }
338
339 class StringTableCreateEntry : public StackObj {
340 private:
341 Thread* _thread;
342 Handle _return;
343 Handle _store;
344 public:
345 StringTableCreateEntry(Thread* thread, Handle store)
346 : _thread(thread), _store(store) {}
347
348 WeakHandle<vm_string_table_data> operator()() { // No dups found
349 WeakHandle<vm_string_table_data> wh =
350 WeakHandle<vm_string_table_data>::create(_store);
351 return wh;
352 }
353 void operator()(bool inserted, WeakHandle<vm_string_table_data>* val) {
354 oop result = val->resolve();
355 assert(result != NULL, "Result should be reachable");
356 _return = Handle(_thread, result);
357 }
358 oop get_return() const {
359 return _return();
360 }
361 };
362
363 oop StringTable::do_intern(Handle string_or_null_h, const jchar* name,
364 int len, uintx hash, TRAPS) {
365 HandleMark hm(THREAD); // cleanup strings created
366 Handle string_h;
367
368 if (!string_or_null_h.is_null()) {
369 string_h = string_or_null_h;
370 } else {
371 string_h = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
372 }
373
374 // Deduplicate the string before it is interned. Note that we should never
375 // deduplicate a string after it has been interned. Doing so will counteract
376 // compiler optimizations done on e.g. interned string literals.
377 Universe::heap()->deduplicate_string(string_h());
378
379 assert(java_lang_String::equals(string_h(), name, len),
380 "string must be properly initialized");
381 assert(len == java_lang_String::length(string_h()), "Must be same length");
382 StringTableLookupOop lookup(THREAD, hash, string_h);
383 StringTableCreateEntry stc(THREAD, string_h);
384
385 bool rehash_warning;
386 _local_table->get_insert_lazy(THREAD, lookup, stc, stc, &rehash_warning);
387 if (rehash_warning) {
388 _needs_rehashing = true;
389 }
390 return stc.get_return();
391 }
392
393 // GC support
394 class StringTableIsAliveCounter : public BoolObjectClosure {
395 BoolObjectClosure* _real_boc;
396 public:
397 size_t _count;
398 size_t _count_total;
399 StringTableIsAliveCounter(BoolObjectClosure* boc) : _real_boc(boc), _count(0),
400 _count_total(0) {}
401 bool do_object_b(oop obj) {
402 bool ret = _real_boc->do_object_b(obj);
403 if (!ret) {
404 ++_count;
405 }
406 ++_count_total;
407 return ret;
408 }
409 };
410
411 void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f,
412 size_t* processed, size_t* removed) {
413 DoNothingClosure dnc;
414 assert(is_alive != NULL, "No closure");
415 StringTableIsAliveCounter stiac(is_alive);
416 OopClosure* tmp = f != NULL ? f : &dnc;
417
418 StringTable::the_table()->_weak_handles->weak_oops_do(&stiac, tmp);
419
420 // This is the serial case without ParState.
421 // Just set the correct number and check for a cleaning phase.
422 the_table()->_uncleaned_items_count = stiac._count;
423 StringTable::the_table()->check_concurrent_work();
424
425 if (processed != NULL) {
426 *processed = stiac._count_total;
427 }
428 if (removed != NULL) {
429 *removed = stiac._count;
430 }
431 }
432
433 void StringTable::oops_do(OopClosure* f) {
434 assert(f != NULL, "No closure");
435 StringTable::the_table()->_weak_handles->oops_do(f);
436 }
437
438 void StringTable::possibly_parallel_unlink(
439 OopStorage::ParState<false, false>* _par_state_string, BoolObjectClosure* cl,
440 size_t* processed, size_t* removed)
441 {
442 DoNothingClosure dnc;
443 assert(cl != NULL, "No closure");
444 StringTableIsAliveCounter stiac(cl);
445
446 _par_state_string->weak_oops_do(&stiac, &dnc);
447
448 // Accumulate the dead strings.
449 the_table()->add_items_count_to_clean(stiac._count);
450
451 *processed = stiac._count_total;
452 *removed = stiac._count;
453 }
454
455 void StringTable::possibly_parallel_oops_do(
456 OopStorage::ParState<false /* concurrent */, false /* const */>*
457 _par_state_string, OopClosure* f)
458 {
459 assert(f != NULL, "No closure");
460 _par_state_string->oops_do(f);
461 }
462
463 // Concurrent work
464 void StringTable::grow(JavaThread* jt) {
465 StringTableHash::GrowTask gt(_local_table);
466 if (!gt.prepare(jt)) {
467 return;
468 }
469 log_trace(stringtable)("Started to grow");
470 {
471 TraceTime timer("Grow", TRACETIME_LOG(Debug, stringtable, perf));
472 while (gt.do_task(jt)) {
473 gt.pause(jt);
474 {
475 ThreadBlockInVM tbivm(jt);
476 }
477 gt.cont(jt);
478 }
479 }
480 gt.done(jt);
481 _current_size = table_size();
482 log_debug(stringtable)("Grown to size:" SIZE_FORMAT, _current_size);
483 }
484
485 struct StringTableDoDelete : StackObj {
486 void operator()(WeakHandle<vm_string_table_data>* val) {
487 /* do nothing */
488 }
489 };
490
491 struct StringTableDeleteCheck : StackObj {
492 long _count;
493 long _item;
494 StringTableDeleteCheck() : _count(0), _item(0) {}
495 bool operator()(WeakHandle<vm_string_table_data>* val) {
496 ++_item;
497 oop tmp = val->peek();
498 if (tmp == NULL) {
499 ++_count;
500 return true;
501 } else {
502 return false;
503 }
504 }
505 };
506
507 void StringTable::clean_dead_entries(JavaThread* jt) {
508 StringTableHash::BulkDeleteTask bdt(_local_table);
509 if (!bdt.prepare(jt)) {
510 return;
511 }
512
513 StringTableDeleteCheck stdc;
514 StringTableDoDelete stdd;
515 {
516 TraceTime timer("Clean", TRACETIME_LOG(Debug, stringtable, perf));
517 while(bdt.do_task(jt, stdc, stdd)) {
518 bdt.pause(jt);
519 {
520 ThreadBlockInVM tbivm(jt);
521 }
522 bdt.cont(jt);
523 }
524 bdt.done(jt);
525 }
526 log_debug(stringtable)("Cleaned %ld of %ld", stdc._count, stdc._item);
527 }
528
529 void StringTable::check_concurrent_work() {
530 if (_has_work) {
531 return;
532 }
533
534 double load_factor = StringTable::get_load_factor();
535 double dead_factor = StringTable::get_dead_factor();
536 // We should clean/resize if we have more dead than alive,
537 // more items than preferred load factor or
538 // more dead items than water mark.
539 if ((dead_factor > load_factor) ||
540 (load_factor > PREF_AVG_LIST_LEN) ||
541 (dead_factor > CLEAN_DEAD_HIGH_WATER_MARK)) {
542 log_debug(stringtable)("Concurrent work triggered, live factor:%g dead factor:%g",
543 load_factor, dead_factor);
544 trigger_concurrent_work();
545 }
546 }
547
548 void StringTable::concurrent_work(JavaThread* jt) {
549 _has_work = false;
550 double load_factor = get_load_factor();
551 log_debug(stringtable, perf)("Concurrent work, live factor: %g", load_factor);
552 // We prefer growing, since that also removes dead items
553 if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
554 grow(jt);
555 } else {
556 clean_dead_entries(jt);
557 }
558 }
559
560 void StringTable::do_concurrent_work(JavaThread* jt) {
561 StringTable::the_table()->concurrent_work(jt);
562 }
563
564 // Rehash
565 bool StringTable::do_rehash() {
566 if (!_local_table->is_safepoint_safe()) {
567 return false;
568 }
569
570 // We use max size
571 StringTableHash* new_table = new StringTableHash(END_SIZE, END_SIZE, REHASH_LEN);
572 // Use alt hash from now on
573 _alt_hash = true;
574 if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) {
575 _alt_hash = false;
576 delete new_table;
577 return false;
578 }
579
580 // free old table
581 delete _local_table;
582 _local_table = new_table;
583
584 return true;
585 }
586
587 void StringTable::try_rehash_table() {
588 static bool rehashed = false;
589 log_debug(stringtable)("Table imbalanced, rehashing called.");
590
591 // Grow instead of rehash.
592 if (get_load_factor() > PREF_AVG_LIST_LEN &&
593 !_local_table->is_max_size_reached()) {
594 log_debug(stringtable)("Choosing growing over rehashing.");
595 trigger_concurrent_work();
596 _needs_rehashing = false;
597 return;
598 }
599 // Already rehashed.
600 if (rehashed) {
601 log_warning(stringtable)("Rehashing already done, still long lists.");
602 trigger_concurrent_work();
603 _needs_rehashing = false;
604 return;
605 }
606
607 murmur_seed = AltHashing::compute_seed();
608 {
609 if (do_rehash()) {
610 rehashed = true;
611 } else {
612 log_info(stringtable)("Resizes in progress rehashing skipped.");
613 }
614 }
615 _needs_rehashing = false;
616 }
617
618 void StringTable::rehash_table() {
619 StringTable::the_table()->try_rehash_table();
620 }
621
622 // Statistics
623 static int literal_size(oop obj) {
624 // NOTE: this would over-count if (pre-JDK8)
625 // java_lang_Class::has_offset_field() is true and the String.value array is
626 // shared by several Strings. However, starting from JDK8, the String.value
627 // array is not shared anymore.
628 if (obj == NULL) {
629 return 0;
630 } else if (obj->klass() == SystemDictionary::String_klass()) {
631 return (obj->size() + java_lang_String::value(obj)->size()) * HeapWordSize;
632 } else {
633 return obj->size();
634 }
635 }
636
637 struct SizeFunc : StackObj {
638 size_t operator()(WeakHandle<vm_string_table_data>* val) {
639 oop s = val->peek();
640 if (s == NULL) {
641 // Dead
642 return 0;
643 }
644 return literal_size(s);
645 };
646 };
647
648 void StringTable::print_table_statistics(outputStream* st,
649 const char* table_name) {
650 SizeFunc sz;
651 _local_table->statistics_to(Thread::current(), sz, st, table_name);
652 }
653
654 // Verification
655 class VerifyStrings : StackObj {
656 public:
657 bool operator()(WeakHandle<vm_string_table_data>* val) {
658 oop s = val->peek();
659 if (s != NULL) {
660 assert(java_lang_String::length(s) >= 0, "Length on string must work.");
661 }
662 return true;
663 };
664 };
665
666 // This verification is part of Universe::verify() and needs to be quick.
667 void StringTable::verify() {
668 Thread* thr = Thread::current();
669 VerifyStrings vs;
670 if (!the_table()->_local_table->try_scan(thr, vs)) {
671 log_info(stringtable)("verify unavailable at this moment");
672 }
673 }
674
675 // Verification and comp
676 class VerifyCompStrings : StackObj {
677 GrowableArray<oop>* _oops;
678 public:
679 size_t _errors;
680 VerifyCompStrings(GrowableArray<oop>* oops) : _oops(oops), _errors(0) {}
681 bool operator()(WeakHandle<vm_string_table_data>* val) {
682 oop s = val->resolve();
683 if (s == NULL) {
684 return true;
685 }
686 int len = _oops->length();
687 for (int i = 0; i < len; i++) {
688 bool eq = java_lang_String::equals(s, _oops->at(i));
689 assert(!eq, "Duplicate strings");
690 if (eq) {
691 _errors++;
692 }
693 }
694 _oops->push(s);
695 return true;
696 };
697 };
698
699 size_t StringTable::verify_and_compare_entries() {
700 Thread* thr = Thread::current();
701 GrowableArray<oop>* oops =
702 new (ResourceObj::C_HEAP, mtInternal)
703 GrowableArray<oop>((int)the_table()->_current_size, true);
704
705 VerifyCompStrings vcs(oops);
706 if (!the_table()->_local_table->try_scan(thr, vcs)) {
707 log_info(stringtable)("verify unavailable at this moment");
708 }
709 delete oops;
710 return vcs._errors;
711 }
712
713 // Dumping
714 class PrintString : StackObj {
715 Thread* _thr;
716 outputStream* _st;
717 public:
718 PrintString(Thread* thr, outputStream* st) : _thr(thr), _st(st) {}
719 bool operator()(WeakHandle<vm_string_table_data>* val) {
720 oop s = val->peek();
721 if (s == NULL) {
722 return true;
723 }
724 typeArrayOop value = java_lang_String::value_no_keepalive(s);
725 int length = java_lang_String::length(s);
726 bool is_latin1 = java_lang_String::is_latin1(s);
727
728 if (length <= 0) {
729 _st->print("%d: ", length);
730 } else {
731 ResourceMark rm(_thr);
732 int utf8_length = length;
733 char* utf8_string;
734
735 if (!is_latin1) {
736 jchar* chars = value->char_at_addr(0);
737 utf8_string = UNICODE::as_utf8(chars, utf8_length);
738 } else {
739 jbyte* bytes = value->byte_at_addr(0);
740 utf8_string = UNICODE::as_utf8(bytes, utf8_length);
741 }
742
743 _st->print("%d: ", utf8_length);
744 HashtableTextDump::put_utf8(_st, utf8_string, utf8_length);
745 }
746 _st->cr();
747 return true;
748 };
749 };
750
751 void StringTable::dump(outputStream* st, bool verbose) {
752 if (!verbose) {
753 the_table()->print_table_statistics(st, "StringTable");
754 } else {
755 Thread* thr = Thread::current();
756 ResourceMark rm(thr);
757 st->print_cr("VERSION: 1.1");
758 PrintString ps(thr, st);
759 if (!the_table()->_local_table->try_scan(thr, ps)) {
760 st->print_cr("dump unavailable at this moment");
761 }
762 }
763 }
764
765 // Utility for dumping strings
766 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
767 DCmdWithParser(output, heap),
768 _verbose("-verbose", "Dump the content of each string in the table",
769 "BOOLEAN", false, "false") {
770 _dcmdparser.add_dcmd_option(&_verbose);
771 }
772
773 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
774 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
775 _verbose.value());
776 VMThread::execute(&dumper);
777 }
778
779 int StringtableDCmd::num_arguments() {
780 ResourceMark rm;
781 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
782 if (dcmd != NULL) {
783 DCmdMark mark(dcmd);
784 return dcmd->_dcmdparser.num_arguments();
785 } else {
786 return 0;
787 }
788 }
789
790 // Sharing
791 #if INCLUDE_CDS_JAVA_HEAP
792 oop StringTable::lookup_shared(const jchar* name, int len, unsigned int hash) {
793 assert(hash == java_lang_String::hash_code(name, len),
794 "hash must be computed using java_lang_String::hash_code");
795 return _shared_table.lookup(name, hash, len);
796 }
797
798 oop StringTable::create_archived_string(oop s, Thread* THREAD) {
799 assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
800
801 if (MetaspaceShared::is_archive_object(s)) {
802 return s;
803 }
804
805 oop new_s = NULL;
806 typeArrayOop v = java_lang_String::value_no_keepalive(s);
807 typeArrayOop new_v =
808 (typeArrayOop)MetaspaceShared::archive_heap_object(v, THREAD);
809 if (new_v == NULL) {
810 return NULL;
811 }
812 new_s = MetaspaceShared::archive_heap_object(s, THREAD);
813 if (new_s == NULL) {
814 return NULL;
815 }
816
817 // adjust the pointer to the 'value' field in the new String oop
818 java_lang_String::set_value_raw(new_s, new_v);
819 return new_s;
820 }
821
822 class CompactStringTableWriter: public CompactHashtableWriter {
823 public:
824 CompactStringTableWriter(int num_entries, CompactHashtableStats* stats) :
825 CompactHashtableWriter(num_entries, stats) {}
826 void add(unsigned int hash, oop string) {
827 CompactHashtableWriter::add(hash, CompressedOops::encode(string));
828 }
829 };
830
831 struct CopyToArchive : StackObj {
832 CompactStringTableWriter* _writer;
833 CopyToArchive(CompactStringTableWriter* writer) : _writer(writer) {}
834 bool operator()(WeakHandle<vm_string_table_data>* val) {
835 oop s = val->peek();
836 if (s == NULL) {
837 return true;
838 }
839 unsigned int hash = java_lang_String::hash_code(s);
840 if (hash == 0) {
841 return true;
842 }
843
844 java_lang_String::set_hash(s, hash);
845 oop new_s = StringTable::create_archived_string(s, Thread::current());
846 if (new_s == NULL) {
847 return true;
848 }
849
850 val->replace(new_s);
851 // add to the compact table
852 _writer->add(hash, new_s);
853 return true;
854 }
855 };
856
857 void StringTable::copy_shared_string_table(CompactStringTableWriter* writer) {
858 assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
859
860 CopyToArchive copy(writer);
861 StringTable::the_table()->_local_table->do_scan(Thread::current(), copy);
862 }
863
864 void StringTable::write_to_archive() {
865 assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
866
867 _shared_table.reset();
868 int num_buckets = the_table()->_items_count / SharedSymbolTableBucketSize;
869 // calculation of num_buckets can result in zero buckets, we need at least one
870 CompactStringTableWriter writer(num_buckets > 1 ? num_buckets : 1,
871 &MetaspaceShared::stats()->string);
872
873 // Copy the interned strings into the "string space" within the java heap
874 copy_shared_string_table(&writer);
875 writer.dump(&_shared_table, "string");
876 }
877
878 void StringTable::serialize(SerializeClosure* soc) {
879 _shared_table.serialize(soc);
880
881 if (soc->writing()) {
882 // Sanity. Make sure we don't use the shared table at dump time
883 _shared_table.reset();
884 } else if (!_shared_string_mapped) {
885 _shared_table.reset();
886 }
887 }
888
889 class SharedStringIterator {
890 OopClosure* _oop_closure;
891 public:
892 SharedStringIterator(OopClosure* f) : _oop_closure(f) {}
893 void do_value(oop string) {
894 _oop_closure->do_oop(&string);
895 }
896 };
897
898 void StringTable::shared_oops_do(OopClosure* f) {
899 SharedStringIterator iter(f);
900 _shared_table.iterate(&iter);
901 }
902 #endif //INCLUDE_CDS_JAVA_HEAP