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