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 // We start with same old size, consider to reduce this
59 #define START_SIZE 16
60 // 2^24 is max size
61 #define END_SIZE 24
62 // If a chain gets to 32 something might be wrong
63 #define REHASH_LEN 32
64 // If we have as many dead items as 50% of the number of bucket
65 #define CLEAN_DEAD_HIGH_WATER_MARK 0.5
66
67 // --------------------------------------------------------------------------
68 StringTable* StringTable::_the_table = NULL;
69 bool StringTable::_shared_string_mapped = false;
70 CompactHashtable<oop, char> StringTable::_shared_table;
71 bool StringTable::_alt_hash = false;
72
73 static juint murmur_seed = 0;
74
75 uintx hash_string(const jchar* s, int len, bool useAlt) {
76 return useAlt ?
77 AltHashing::murmur3_32(murmur_seed, s, len) :
78 java_lang_String::hash_code(s, len);
79 }
80
81 class StringTableConfig : public StringTableHash::BaseConfig {
82 private:
83 public:
84 static uintx get_hash(WeakHandle<vm_string_table_data> const& value,
85 bool* is_dead) {
86 EXCEPTION_MARK;
87 oop val_oop = value.peek();
88 if (val_oop == NULL) {
89 *is_dead = true;
90 return 0;
91 }
92 *is_dead = false;
93 ResourceMark rm(THREAD);
94 // All String oops are hashed as unicode
95 int length;
96 jchar* chars = java_lang_String::as_unicode_string(val_oop, length, THREAD);
97 if (chars != NULL) {
98 return hash_string(chars, length, StringTable::_alt_hash);
99 }
100 vm_exit_out_of_memory(length, OOM_MALLOC_ERROR, "get hash from oop");
101 return 0;
102 }
103 // We use default allocation/deallocation but counted
104 static void* allocate_node(size_t size,
105 WeakHandle<vm_string_table_data> const& value) {
106 StringTable::item_added();
107 return StringTableHash::BaseConfig::allocate_node(size, value);
108 }
109 static void free_node(void* memory,
110 WeakHandle<vm_string_table_data> const& value) {
111 value.release();
112 StringTableHash::BaseConfig::free_node(memory, value);
113 StringTable::item_removed();
114 }
115 };
116
117 class StringTableLookupJchar {
118 private:
119 Thread* _thread;
120 uintx _hash;
121 int _len;
122 const jchar* _str;
123 Handle _found;
124
125 public:
126 StringTableLookupJchar(Thread* thread, uintx hash, const jchar* key, int len)
127 : _thread(thread), _hash(hash), _str(key), _len(len) {
128 }
129 uintx get_hash() const {
130 return _hash;
131 }
132 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
133 oop val_oop = value->peek();
134 if (val_oop == NULL) {
135 // dead oop, mark this hash dead for cleaning
136 *is_dead = true;
137 return false;
138 }
139 bool equals = java_lang_String::equals(val_oop, (jchar*)_str, _len);
140 if (!equals) {
141 return false;
142 }
143 // Need to resolve weak handle and Handleize through possible safepoint.
144 _found = Handle(_thread, value->resolve());
145 return true;
146 }
147 };
148
149 class StringTableLookupOop : public StackObj {
150 private:
151 Thread* _thread;
152 uintx _hash;
153 Handle _find;
154 Handle _found; // Might be a different oop with the same value that's already
155 // in the table, which is the point.
156 public:
157 StringTableLookupOop(Thread* thread, uintx hash, Handle handle)
158 : _thread(thread), _hash(hash), _find(handle) { }
159
160 uintx get_hash() const {
161 return _hash;
162 }
163
164 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
165 oop val_oop = value->peek();
166 if (val_oop == NULL) {
167 // dead oop, mark this hash dead for cleaning
168 *is_dead = true;
169 return false;
170 }
171 bool equals = java_lang_String::equals(_find(), val_oop);
172 if (!equals) {
173 return false;
174 }
175 // Need to resolve weak handle and Handleize through possible safepoint.
176 _found = Handle(_thread, value->resolve());
177 return true;
178 }
179 };
180
181 StringTable::StringTable() : _local_table(NULL), _current_size(0), _has_work(0),
182 _needs_rehashing(false), _weak_handles(NULL), _items(0), _uncleaned_items(0) {
183 _weak_handles = new OopStorage("StringTable weak",
184 StringTableWeakAlloc_lock,
185 StringTableWeakActive_lock);
186 _local_table = new StringTableHash(START_SIZE, END_SIZE, REHASH_LEN);
187 _current_size = ((size_t)1) << START_SIZE;
188 }
189
190 size_t StringTable::item_added() {
191 return Atomic::add((size_t)1, &(the_table()->_items));
192 }
193
194 size_t StringTable::items_to_clean(size_t ncl) {
195 size_t total = Atomic::add((size_t)ncl, &(the_table()->_uncleaned_items));
196 log_trace(stringtable)(
197 "Uncleaned items:" SIZE_FORMAT " added: " SIZE_FORMAT " total:" SIZE_FORMAT,
198 the_table()->_uncleaned_items, ncl, total);
199 return total;
200 }
201
202 void StringTable::item_removed() {
203 Atomic::add((size_t)-1, &(the_table()->_items));
204 Atomic::add((size_t)-1, &(the_table()->_uncleaned_items));
205 }
206
207 double StringTable::get_load_factor() {
208 return (_items*1.0)/_current_size;
209 }
210
211 double StringTable::get_dead_factor() {
212 return (_uncleaned_items*1.0)/_current_size;
213 }
214
215 oop StringTable::lookup(Symbol* symbol) {
216 ResourceMark rm;
217 int length;
218 jchar* chars = symbol->as_unicode(length);
219 return lookup(chars, length);
220 }
221
222 oop StringTable::lookup(jchar* name, int len) {
223 unsigned int hash = java_lang_String::hash_code(name, len);
224 oop string = StringTable::the_table()->lookup_shared(name, len, hash);
225 if (string != NULL) {
226 return string;
227 }
228 if (StringTable::_alt_hash) {
229 hash = hash_string(name, len, true);
230 }
231 return StringTable::the_table()->do_lookup( name, len, hash);
232 }
233
234 class StringTableGet : public StackObj {
235 Thread* _thread;
236 Handle _return;
237 public:
238 StringTableGet(Thread* thread) : _thread(thread) {}
239 void operator()(WeakHandle<vm_string_table_data>* val) {
240 oop result = val->resolve();
241 assert(result != NULL, "Result should be reachable");
242 _return = Handle(_thread, result);
243 }
244 oop get_res_oop() {
245 return _return();
246 }
247 };
248
249 oop StringTable::do_lookup(jchar* name, int len, uintx hash) {
250 Thread* thread = Thread::current();
251 StringTableLookupJchar lookup(thread, hash, name, len);
252 StringTableGet stg(thread);
253 bool rehash_warning;
254 _local_table->get(thread, lookup, stg, &rehash_warning);
255 if (rehash_warning) {
256 _needs_rehashing = true;
257 }
258 return stg.get_res_oop();
259 }
260
261 class StringTableCreateEntry : public StackObj {
262 private:
263 Thread* _thread;
264 Handle _return;
265 Handle _store;
266 public:
267 StringTableCreateEntry(Thread* thread, Handle store)
268 : _thread(thread), _store(store) {}
269
270 WeakHandle<vm_string_table_data> operator()() { // No dups found
271 WeakHandle<vm_string_table_data> wh =
272 WeakHandle<vm_string_table_data>::create(_store);
273 return wh;
274 }
275 void operator()(bool inserted, WeakHandle<vm_string_table_data>* val) {
276 oop result = val->resolve();
277 assert(result != NULL, "Result should be reachable");
278 _return = Handle(_thread, result);
279 }
280 oop get_return() const {
281 return _return();
282 }
283 };
284
285 oop StringTable::intern(Handle string_or_null_h, jchar* name, int len, TRAPS) {
286 // shared table always uses java_lang_String::hash_code
287 unsigned int hash = java_lang_String::hash_code(name, len);
288 oop found_string = StringTable::the_table()->lookup_shared(name, len, hash);
289 if (found_string != NULL) {
290 return found_string;
291 }
292 if (StringTable::_alt_hash) {
293 hash = hash_string(name, len, true);
294 }
295 return StringTable::the_table()->do_intern(string_or_null_h, name, len,
296 hash, CHECK_NULL);
297 }
298
299 oop StringTable::do_intern(Handle string_or_null_h, jchar* name,
300 int len, uintx hash, TRAPS) {
301 HandleMark hm(THREAD); // cleanup strings created
302 Handle string_h;
303
304 if (!string_or_null_h.is_null()) {
305 string_h = string_or_null_h;
306 } else {
307 string_h = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
308 }
309
310 // Deduplicate the string before it is interned. Note that we should never
311 // deduplicate a string after it has been interned. Doing so will counteract
312 // compiler optimizations done on e.g. interned string literals.
313 Universe::heap()->deduplicate_string(string_h());
314
315 assert(java_lang_String::equals(string_h(), name, len),
316 "string must be properly initialized");
317 assert(len == java_lang_String::length(string_h()), "Must be same length");
318 StringTableLookupOop lookup(THREAD, hash, string_h);
319 StringTableCreateEntry stc(THREAD, string_h);
320
321 bool rehash_warning;
322 _local_table->get_insert_lazy(THREAD, lookup, stc, stc, &rehash_warning);
323 if (rehash_warning) {
324 _needs_rehashing = true;
325 }
326 return stc.get_return();
327 }
328
329 oop StringTable::intern(Symbol* symbol, TRAPS) {
330 if (symbol == NULL) return NULL;
331 ResourceMark rm(THREAD);
332 int length;
333 jchar* chars = symbol->as_unicode(length);
334 Handle string;
335 oop result = intern(string, chars, length, CHECK_NULL);
336 return result;
337 }
338
339 oop StringTable::intern(oop string, TRAPS) {
340 if (string == NULL) return NULL;
341 ResourceMark rm(THREAD);
342 int length;
343 Handle h_string (THREAD, string);
344 jchar* chars = java_lang_String::as_unicode_string(string, length,
345 CHECK_NULL);
346 oop result = intern(h_string, chars, length, CHECK_NULL);
347 return result;
348 }
349
350 oop StringTable::intern(const char* utf8_string, TRAPS) {
351 if (utf8_string == NULL) return NULL;
352 ResourceMark rm(THREAD);
353 int length = UTF8::unicode_length(utf8_string);
354 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
355 UTF8::convert_to_unicode(utf8_string, chars, length);
356 Handle string;
357 oop result = intern(string, chars, length, CHECK_NULL);
358 return result;
359 }
360
361 size_t StringTable::table_size(Thread* thread) {
362 return ((size_t)(1)) << _local_table->get_size_log2(thread != NULL ? thread
363 : Thread::current());
364 }
365
366 class StringTableIsAliveCounter : public BoolObjectClosure {
367 BoolObjectClosure* _real_boc;
368 public:
369 size_t _count;
370 size_t _count_total;
371 StringTableIsAliveCounter(BoolObjectClosure* boc) : _real_boc(boc), _count(0),
372 _count_total(0) {}
373 bool do_object_b(oop obj) {
374 bool ret = _real_boc->do_object_b(obj);
375 if (!ret) {
376 ++_count;
377 }
378 ++_count_total;
379 return ret;
380 }
381 };
382
383 void StringTable::trigger_concurrent_work() {
384 MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
385 the_table()->_has_work = true;
386 Service_lock->notify_all();
387 }
388
389 void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f,
390 int* processed, int* removed) {
391 DoNothingClosure dnc;
392 assert(is_alive != NULL, "No closure");
393 StringTableIsAliveCounter stiac(is_alive);
394 OopClosure* tmp = f != NULL ? f : &dnc;
395
396 StringTable::the_table()->_weak_handles->weak_oops_do(&stiac, tmp);
397
398 StringTable::the_table()->items_to_clean(stiac._count);
399 StringTable::the_table()->check_concurrent_work();
400 if (processed != NULL) {
401 *processed = (int) stiac._count_total;
402 }
403 if (removed != NULL) {
404 *removed = (int) stiac._count;
405 }
406 }
407
408 void StringTable::oops_do(OopClosure* f) {
409 assert(f != NULL, "No closure");
410 StringTable::the_table()->_weak_handles->oops_do(f);
411 }
412
413 void StringTable::possibly_parallel_unlink(
414 OopStorage::ParState<false, false>* _par_state_string, BoolObjectClosure* cl,
415 int* processed, int* removed)
416 {
417 DoNothingClosure dnc;
418 assert(cl != NULL, "No closure");
419 StringTableIsAliveCounter stiac(cl);
420
421 _par_state_string->weak_oops_do(&stiac, &dnc);
422
423 StringTable::the_table()->items_to_clean(stiac._count);
424 StringTable::the_table()->check_concurrent_work();
425 *processed = (int) stiac._count_total;
426 *removed = (int) stiac._count;
427 }
428
429 void StringTable::possibly_parallel_oops_do(
430 OopStorage::ParState<false /* concurrent */, false /* const */>*
431 _par_state_string, OopClosure* f)
432 {
433 assert(f != NULL, "No closure");
434 _par_state_string->oops_do(f);
435 }
436
437 struct StringTableDeleteCheck {
438 long _count;
439 long _item;
440 StringTableDeleteCheck() : _count(0), _item(0) {}
441 bool operator()(WeakHandle<vm_string_table_data>* val) {
442 ++_item;
443 oop tmp = val->peek();
444 if (tmp == NULL) {
445 ++_count;
446 return true;
447 } else {
448 return false;
449 }
450 }
451 };
452
453 struct StringTableDoDelete {
454 long _count;
455 StringTableDoDelete() : _count(0) {}
456 void operator()(WeakHandle<vm_string_table_data>* val) {
457 ++_count;
458 }
459 };
460
461 void StringTable::grow(JavaThread* jt) {
462 StringTableHash::GrowTask gt(_local_table);
463 if (!gt.prepare(jt)) {
464 return;
465 }
466 log_trace(stringtable)("Started to growed");
467 {
468 TraceTime timer("Grow", TRACETIME_LOG(Debug, stringtable, perf));
469 while(gt.doTask(jt)) {
470 gt.pause(jt);
471 {
472 ThreadBlockInVM tbivm(jt);
473 }
474 gt.cont(jt);
475 }
476 }
477 gt.done(jt);
478 _current_size = table_size(jt);
479 log_debug(stringtable)("Growed to size:" SIZE_FORMAT, _current_size);
480 }
481
482 void StringTable::clean_dead_entries(JavaThread* jt) {
483 StringTableHash::BulkDeleteTask bdt(_local_table);
484 if (!bdt.prepare(jt)) {
485 return;
486 }
487
488 StringTableDeleteCheck stdc;
489 StringTableDoDelete stdd;
490 bool interrupted = false;
491 {
492 TraceTime timer("Clean", TRACETIME_LOG(Debug, stringtable, perf));
493 while(bdt.doTask(jt, stdc, stdd)) {
494 bdt.pause(jt);
495 {
496 ThreadBlockInVM tbivm(jt);
497 }
498 if (!bdt.cont(jt)) {
499 interrupted = true;
500 break;
501 }
502 }
503 }
504 if (interrupted) {
505 _has_work = true;
506 } else {
507 bdt.done(jt);
508 }
509 log_debug(stringtable)("Cleaned %ld of %ld", stdc._count, stdc._item);
510 }
511
512 void StringTable::check_concurrent_work() {
513 if (_has_work) {
514 return;
515 }
516 double fact = StringTable::get_load_factor();
517 double dead_fact = StringTable::get_dead_factor();
518 // We should clean/resize if we have more dead than alive,
519 // more items than preferred load factor or
520 // more dead items than water mark.
521 if ((dead_fact > fact) ||
522 (fact > PREF_AVG_LIST_LEN) ||
523 (dead_fact > CLEAN_DEAD_HIGH_WATER_MARK)) {
524 log_debug(stringtable)("Concurrent work triggered, live factor:%g dead factor:%g",
525 fact, dead_fact);
526 trigger_concurrent_work();
527 }
528 }
529
530 void StringTable::concurrent_work(JavaThread* jt) {
531 _has_work = false;
532 double fact = get_load_factor();
533 log_debug(stringtable, perf)("Concurrent work, live factor: %g", fact);
534 // We prefer growing, since that also removes dead items
535 if (fact > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
536 grow(jt);
537 } else {
538 clean_dead_entries(jt);
539 }
540 }
541
542 void StringTable::do_concurrent_work(JavaThread* jt) {
543 StringTable::the_table()->concurrent_work(jt);
544 }
545
546 bool StringTable::do_rehash() {
547 if (!_local_table->is_safepoint_safe()) {
548 return false;
549 }
550
551 // We use max size
552 StringTableHash* new_table = new StringTableHash(END_SIZE, END_SIZE, REHASH_LEN);
553 // Use alt hash from now on
554 _alt_hash = true;
555 if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) {
556 _alt_hash = false;
557 delete new_table;
558 return false;
559 }
560
561 // free old table
562 delete _local_table;
563 _local_table = new_table;
564
565 return true;
566 }
567
568 void StringTable::try_rehash_table() {
569 static bool rehashed = false;
570 log_debug(stringtable)("Table imbalanced, rehashing called.");
571
572 // Grow instead of rehash.
573 if (get_load_factor() > PREF_AVG_LIST_LEN &&
574 !_local_table->is_max_size_reached()) {
575 log_debug(stringtable)("Choosing growing over rehashing.");
576 trigger_concurrent_work();
577 _needs_rehashing = false;
578 return;
579 }
580 // Already rehashed.
581 if (rehashed) {
582 log_warning(stringtable)("Rehashing already done, still long lists.");
583 trigger_concurrent_work();
584 _needs_rehashing = false;
585 return;
586 }
587
588 murmur_seed = AltHashing::compute_seed();
589 {
590 if (do_rehash()) {
591 rehashed = true;
592 } else {
593 log_info(stringtable)("Resizes in progress rehashing skipped.");
594 }
595 }
596 _needs_rehashing = false;
597 }
598
599 void StringTable::rehash_table() {
600 StringTable::the_table()->try_rehash_table();
601 }
602
603 oop StringTable::lookup_shared(jchar* name, int len, unsigned int hash) {
604 assert(hash == java_lang_String::hash_code(name, len),
605 "hash must be computed using java_lang_String::hash_code");
606 return _shared_table.lookup((const char*)name, hash, len);
607 }
608
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 {
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 class PrintString {
641 Thread* _thr;
642 outputStream* _st;
643 public:
644 PrintString(Thread* thr, outputStream* st) : _thr(thr), _st(st) {}
645 bool operator()(WeakHandle<vm_string_table_data>* val) {
646 oop s = val->peek();
647 if (s == NULL) {
648 return true;
649 }
650 typeArrayOop value = java_lang_String::value_no_keepalive(s);
651 int length = java_lang_String::length(s);
652 bool is_latin1 = java_lang_String::is_latin1(s);
653
654 if (length <= 0) {
655 _st->print("%d: ", length);
656 } else {
657 ResourceMark rm(_thr);
658 int utf8_length = length;
659 char* utf8_string;
660
661 if (!is_latin1) {
662 jchar* chars = value->char_at_addr(0);
663 utf8_string = UNICODE::as_utf8(chars, utf8_length);
664 } else {
665 jbyte* bytes = value->byte_at_addr(0);
666 utf8_string = UNICODE::as_utf8(bytes, utf8_length);
667 }
668
669 _st->print("%d: ", utf8_length);
670 HashtableTextDump::put_utf8(_st, utf8_string, utf8_length);
671 }
672 _st->cr();
673 return true;
674 };
675 };
676
677 void StringTable::dump(outputStream* st, bool verbose) {
678 if (!verbose) {
679 the_table()->print_table_statistics(st, "StringTable");
680 } else {
681 Thread* thr = Thread::current();
682 ResourceMark rm(thr);
683 st->print_cr("VERSION: 1.1");
684 PrintString ps(thr, st);
685 if (!the_table()->_local_table->try_scan(thr, ps)) {
686 st->print_cr("dump unavailable at this moment");
687 }
688 }
689 }
690
691 class VerifyStrings {
692 public:
693 bool operator()(WeakHandle<vm_string_table_data>* val) {
694 oop s = val->peek();
695 if (s != NULL) {
696 assert(java_lang_String::length(s) >= 0, "Length on string must work.");
697 }
698 return true;
699 };
700 };
701
702 // This verification is part of Universe::verify() and needs to be quick.
703 void StringTable::verify() {
704 Thread* thr = Thread::current();
705 VerifyStrings vs;
706 if (!the_table()->_local_table->try_scan(thr, vs)) {
707 log_info(stringtable)("verify unavailable at this moment");
708 }
709 }
710
711 // Utility for dumping strings
712 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
713 DCmdWithParser(output, heap),
714 _verbose("-verbose", "Dump the content of each string in the table",
715 "BOOLEAN", false, "false") {
716 _dcmdparser.add_dcmd_option(&_verbose);
717 }
718
719 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
720 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
721 _verbose.value());
722 VMThread::execute(&dumper);
723 }
724
725 int StringtableDCmd::num_arguments() {
726 ResourceMark rm;
727 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
728 if (dcmd != NULL) {
729 DCmdMark mark(dcmd);
730 return dcmd->_dcmdparser.num_arguments();
731 } else {
732 return 0;
733 }
734 }
735
736 #if INCLUDE_CDS_JAVA_HEAP
737 // Sharing
738 oop StringTable::create_archived_string(oop s, Thread* THREAD) {
739 assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
740
741 oop new_s = NULL;
742 typeArrayOop v = java_lang_String::value_no_keepalive(s);
743 typeArrayOop new_v =
744 (typeArrayOop)MetaspaceShared::archive_heap_object(v, THREAD);
745 if (new_v == NULL) {
746 return NULL;
747 }
748 new_s = MetaspaceShared::archive_heap_object(s, THREAD);
749 if (new_s == NULL) {
750 return NULL;
751 }
752
753 // adjust the pointer to the 'value' field in the new String oop
754 java_lang_String::set_value_raw(new_s, new_v);
755 return new_s;
756 }
757
758 struct CopyArchive {
759 CompactStringTableWriter* _writer;
760 CopyArchive(CompactStringTableWriter* writer) : _writer(writer) {}
761 bool operator()(WeakHandle<vm_string_table_data>* val) {
762 oop s = val->peek();
763 if (s == NULL) {
764 return true;
765 }
766 unsigned int hash = java_lang_String::hash_code(s);
767 if (hash == 0) {
768 return true;
769 }
770
771 java_lang_String::set_hash(s, hash);
772 oop new_s = StringTable::create_archived_string(s, Thread::current());
773 if (new_s == NULL) {
774 return true;
775 }
776
777 val->replace(new_s);
778 // add to the compact table
779 _writer->add(hash, new_s);
780 return true;
781 }
782 };
783
784 void StringTable::copy_shared_string(CompactStringTableWriter* writer) {
785 assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
786
787 CopyArchive copy(writer);
788 StringTable::the_table()->_local_table->do_scan(Thread::current(), copy);
789 }
790
791 void StringTable::write_to_archive() {
792 assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
793
794 _shared_table.reset();
795 int num_buckets = the_table()->_items / SharedSymbolTableBucketSize;
796 // calculation of num_buckets can result in zero buckets, we need at least one
797 CompactStringTableWriter writer(num_buckets > 1 ? num_buckets : 1,
798 &MetaspaceShared::stats()->string);
799
800 // Copy the interned strings into the "string space" within the java heap
801 copy_shared_string(&writer);
802 writer.dump(&_shared_table);
803 }
804
805 void StringTable::serialize(SerializeClosure* soc) {
806 _shared_table.set_type(CompactHashtable<oop, char>::_string_table);
807 _shared_table.serialize(soc);
808
809 if (soc->writing()) {
810 // Sanity. Make sure we don't use the shared table at dump time
811 _shared_table.reset();
812 } else if (!_shared_string_mapped) {
813 _shared_table.reset();
814 }
815 }
816
817 void StringTable::shared_oops_do(OopClosure* f) {
818 _shared_table.oops_do(f);
819 }
820
821 #endif //INCLUDE_CDS_JAVA_HEAP