1 /*
2 * Copyright (c) 1997, 2019, 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/oopStorageSet.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/resourceArea.hpp"
40 #include "memory/universe.hpp"
41 #include "oops/access.inline.hpp"
42 #include "oops/compressedOops.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 #include "utilities/utf8.hpp"
57
58 // We prefer short chains of avg 2
59 const double PREF_AVG_LIST_LEN = 2.0;
60 // 2^24 is max size
61 const size_t END_SIZE = 24;
62 // If a chain gets to 100 something might be wrong
63 const size_t REHASH_LEN = 100;
64 // If we have as many dead items as 50% of the number of bucket
65 const double CLEAN_DEAD_HIGH_WATER_MARK = 0.5;
66
67 #if INCLUDE_CDS_JAVA_HEAP
68 inline oop read_string_from_compact_hashtable(address base_address, u4 offset) {
69 assert(sizeof(narrowOop) == sizeof(offset), "must be");
70 narrowOop v = (narrowOop)offset;
71 return HeapShared::decode_from_archive(v);
72 }
73
74 static CompactHashtable<
75 const jchar*, oop,
76 read_string_from_compact_hashtable,
77 java_lang_String::equals
78 > _shared_table;
79 #endif
80
81 // --------------------------------------------------------------------------
82
83 typedef ConcurrentHashTable<StringTableConfig, mtSymbol> StringTableHash;
84 static StringTableHash* _local_table = NULL;
85
86 volatile bool StringTable::_has_work = false;
87 volatile bool StringTable::_needs_rehashing = false;
88
89 volatile size_t StringTable::_uncleaned_items_count = 0;
90
91 static size_t _current_size = 0;
92 static volatile size_t _items_count = 0;
93
94 volatile bool _alt_hash = false;
95 static juint murmur_seed = 0;
96
97 uintx hash_string(const jchar* s, int len, bool useAlt) {
98 return useAlt ?
99 AltHashing::murmur3_32(murmur_seed, s, len) :
100 java_lang_String::hash_code(s, len);
101 }
102
103 class StringTableConfig : public StackObj {
104 private:
105 public:
106 typedef WeakHandle Value;
107
108 static uintx get_hash(Value const& value, bool* is_dead) {
109 EXCEPTION_MARK;
110 oop val_oop = value.peek();
111 if (val_oop == NULL) {
112 *is_dead = true;
113 return 0;
114 }
115 *is_dead = false;
116 ResourceMark rm(THREAD);
117 // All String oops are hashed as unicode
118 int length;
119 jchar* chars = java_lang_String::as_unicode_string(val_oop, length, THREAD);
120 if (chars != NULL) {
121 return hash_string(chars, length, _alt_hash);
122 }
123 vm_exit_out_of_memory(length, OOM_MALLOC_ERROR, "get hash from oop");
124 return 0;
125 }
126 // We use default allocation/deallocation but counted
127 static void* allocate_node(size_t size, Value const& value) {
128 StringTable::item_added();
129 return AllocateHeap(size, mtSymbol);
130 }
131 static void free_node(void* memory, Value const& value) {
132 value.release(OopStorageSet::string_table_weak());
133 FreeHeap(memory);
134 StringTable::item_removed();
135 }
136 };
137
138 class StringTableLookupJchar : StackObj {
139 private:
140 Thread* _thread;
141 uintx _hash;
142 int _len;
143 const jchar* _str;
144 Handle _found;
145
146 public:
147 StringTableLookupJchar(Thread* thread, uintx hash, const jchar* key, int len)
148 : _thread(thread), _hash(hash), _len(len), _str(key) {
149 }
150 uintx get_hash() const {
151 return _hash;
152 }
153 bool equals(WeakHandle* value, bool* is_dead) {
154 oop val_oop = value->peek();
155 if (val_oop == NULL) {
156 // dead oop, mark this hash dead for cleaning
157 *is_dead = true;
158 return false;
159 }
160 bool equals = java_lang_String::equals(val_oop, _str, _len);
161 if (!equals) {
162 return false;
163 }
164 // Need to resolve weak handle and Handleize through possible safepoint.
165 _found = Handle(_thread, value->resolve());
166 return true;
167 }
168 };
169
170 class StringTableLookupOop : public StackObj {
171 private:
172 Thread* _thread;
173 uintx _hash;
174 Handle _find;
175 Handle _found; // Might be a different oop with the same value that's already
176 // in the table, which is the point.
177 public:
178 StringTableLookupOop(Thread* thread, uintx hash, Handle handle)
179 : _thread(thread), _hash(hash), _find(handle) { }
180
181 uintx get_hash() const {
182 return _hash;
183 }
184
185 bool equals(WeakHandle* value, bool* is_dead) {
186 oop val_oop = value->peek();
187 if (val_oop == NULL) {
188 // dead oop, mark this hash dead for cleaning
189 *is_dead = true;
190 return false;
191 }
192 bool equals = java_lang_String::equals(_find(), val_oop);
193 if (!equals) {
194 return false;
195 }
196 // Need to resolve weak handle and Handleize through possible safepoint.
197 _found = Handle(_thread, value->resolve());
198 return true;
199 }
200 };
201
202 static size_t ceil_log2(size_t val) {
203 size_t ret;
204 for (ret = 1; ((size_t)1 << ret) < val; ++ret);
205 return ret;
206 }
207
208 void StringTable::create_table() {
209 size_t start_size_log_2 = ceil_log2(StringTableSize);
210 _current_size = ((size_t)1) << start_size_log_2;
211 log_trace(stringtable)("Start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
212 _current_size, start_size_log_2);
213 _local_table = new StringTableHash(start_size_log_2, END_SIZE, REHASH_LEN);
214 }
215
216 size_t StringTable::item_added() {
217 return Atomic::add(&_items_count, (size_t)1);
218 }
219
220 void StringTable::item_removed() {
221 Atomic::add(&_items_count, (size_t)-1);
222 }
223
224 double StringTable::get_load_factor() {
225 return double(_items_count)/double(_current_size);
226 }
227
228 double StringTable::get_dead_factor() {
229 return double(_uncleaned_items_count)/double(_current_size);
230 }
231
232 size_t StringTable::table_size() {
233 return ((size_t)1) << _local_table->get_size_log2(Thread::current());
234 }
235
236 void StringTable::trigger_concurrent_work() {
237 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
238 _has_work = true;
239 Service_lock->notify_all();
240 }
241
242 // Probing
243 oop StringTable::lookup(Symbol* symbol) {
244 ResourceMark rm;
245 int length;
246 jchar* chars = symbol->as_unicode(length);
247 return lookup(chars, length);
248 }
249
250 oop StringTable::lookup(const jchar* name, int len) {
251 unsigned int hash = java_lang_String::hash_code(name, len);
252 oop string = lookup_shared(name, len, hash);
253 if (string != NULL) {
254 return string;
255 }
256 if (_alt_hash) {
257 hash = hash_string(name, len, true);
258 }
259 return do_lookup(name, len, hash);
260 }
261
262 class StringTableGet : public StackObj {
263 Thread* _thread;
264 Handle _return;
265 public:
266 StringTableGet(Thread* thread) : _thread(thread) {}
267 void operator()(WeakHandle* val) {
268 oop result = val->resolve();
269 assert(result != NULL, "Result should be reachable");
270 _return = Handle(_thread, result);
271 }
272 oop get_res_oop() {
273 return _return();
274 }
275 };
276
277 oop StringTable::do_lookup(const jchar* name, int len, uintx hash) {
278 Thread* thread = Thread::current();
279 StringTableLookupJchar lookup(thread, hash, name, len);
280 StringTableGet stg(thread);
281 bool rehash_warning;
282 _local_table->get(thread, lookup, stg, &rehash_warning);
283 update_needs_rehash(rehash_warning);
284 return stg.get_res_oop();
285 }
286
287 // Interning
288 oop StringTable::intern(Symbol* symbol, TRAPS) {
289 if (symbol == NULL) return NULL;
290 ResourceMark rm(THREAD);
291 int length;
292 jchar* chars = symbol->as_unicode(length);
293 Handle string;
294 oop result = intern(string, chars, length, CHECK_NULL);
295 return result;
296 }
297
298 oop StringTable::intern(oop string, TRAPS) {
299 if (string == NULL) return NULL;
300 ResourceMark rm(THREAD);
301 int length;
302 Handle h_string (THREAD, string);
303 jchar* chars = java_lang_String::as_unicode_string(string, length,
304 CHECK_NULL);
305 oop result = intern(h_string, chars, length, CHECK_NULL);
306 return result;
307 }
308
309 oop StringTable::intern(const char* utf8_string, TRAPS) {
310 if (utf8_string == NULL) return NULL;
311 ResourceMark rm(THREAD);
312 int length = UTF8::unicode_length(utf8_string);
313 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
314 UTF8::convert_to_unicode(utf8_string, chars, length);
315 Handle string;
316 oop result = intern(string, chars, length, CHECK_NULL);
317 return result;
318 }
319
320 oop StringTable::intern(Handle string_or_null_h, const jchar* name, int len, TRAPS) {
321 // shared table always uses java_lang_String::hash_code
322 unsigned int hash = java_lang_String::hash_code(name, len);
323 oop found_string = lookup_shared(name, len, hash);
324 if (found_string != NULL) {
325 return found_string;
326 }
327 if (_alt_hash) {
328 hash = hash_string(name, len, true);
329 }
330 found_string = do_lookup(name, len, hash);
331 if (found_string != NULL) {
332 return found_string;
333 }
334 return do_intern(string_or_null_h, name, len, hash, THREAD);
335 }
336
337 oop StringTable::do_intern(Handle string_or_null_h, const jchar* name,
338 int len, uintx hash, TRAPS) {
339 HandleMark hm(THREAD); // cleanup strings created
340 Handle string_h;
341
342 if (!string_or_null_h.is_null()) {
343 string_h = string_or_null_h;
344 } else {
345 string_h = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
346 }
347
348 // Deduplicate the string before it is interned. Note that we should never
349 // deduplicate a string after it has been interned. Doing so will counteract
350 // compiler optimizations done on e.g. interned string literals.
351 Universe::heap()->deduplicate_string(string_h());
352
353 assert(java_lang_String::equals(string_h(), name, len),
354 "string must be properly initialized");
355 assert(len == java_lang_String::length(string_h()), "Must be same length");
356
357 StringTableLookupOop lookup(THREAD, hash, string_h);
358 StringTableGet stg(THREAD);
359
360 bool rehash_warning;
361 do {
362 // Callers have already looked up the String using the jchar* name, so just go to add.
363 WeakHandle wh(OopStorageSet::string_table_weak(), string_h);
364 // The hash table takes ownership of the WeakHandle, even if it's not inserted.
365 if (_local_table->insert(THREAD, lookup, wh, &rehash_warning)) {
366 update_needs_rehash(rehash_warning);
367 return wh.resolve();
368 }
369 // In case another thread did a concurrent add, return value already in the table.
370 // This could fail if the String got gc'ed concurrently, so loop back until success.
371 if (_local_table->get(THREAD, lookup, stg, &rehash_warning)) {
372 update_needs_rehash(rehash_warning);
373 return stg.get_res_oop();
374 }
375 } while(true);
376 }
377
378 // Concurrent work
379 void StringTable::grow(JavaThread* jt) {
380 StringTableHash::GrowTask gt(_local_table);
381 if (!gt.prepare(jt)) {
382 return;
383 }
384 log_trace(stringtable)("Started to grow");
385 {
386 TraceTime timer("Grow", TRACETIME_LOG(Debug, stringtable, perf));
387 while (gt.do_task(jt)) {
388 gt.pause(jt);
389 {
390 ThreadBlockInVM tbivm(jt);
391 }
392 gt.cont(jt);
393 }
394 }
395 gt.done(jt);
396 _current_size = table_size();
397 log_debug(stringtable)("Grown to size:" SIZE_FORMAT, _current_size);
398 }
399
400 struct StringTableDoDelete : StackObj {
401 void operator()(WeakHandle* val) {
402 /* do nothing */
403 }
404 };
405
406 struct StringTableDeleteCheck : StackObj {
407 long _count;
408 long _item;
409 StringTableDeleteCheck() : _count(0), _item(0) {}
410 bool operator()(WeakHandle* val) {
411 ++_item;
412 oop tmp = val->peek();
413 if (tmp == NULL) {
414 ++_count;
415 return true;
416 } else {
417 return false;
418 }
419 }
420 };
421
422 void StringTable::clean_dead_entries(JavaThread* jt) {
423 StringTableHash::BulkDeleteTask bdt(_local_table);
424 if (!bdt.prepare(jt)) {
425 return;
426 }
427
428 StringTableDeleteCheck stdc;
429 StringTableDoDelete stdd;
430 {
431 TraceTime timer("Clean", TRACETIME_LOG(Debug, stringtable, perf));
432 while(bdt.do_task(jt, stdc, stdd)) {
433 bdt.pause(jt);
434 {
435 ThreadBlockInVM tbivm(jt);
436 }
437 bdt.cont(jt);
438 }
439 bdt.done(jt);
440 }
441 log_debug(stringtable)("Cleaned %ld of %ld", stdc._count, stdc._item);
442 }
443
444 void StringTable::gc_notification(size_t dead_count) {
445 _uncleaned_items_count += dead_count;
446
447 if (_has_work) {
448 return;
449 }
450
451 double load_factor = StringTable::get_load_factor();
452 double dead_factor = StringTable::get_dead_factor();
453 // We should clean/resize if we have more dead than alive,
454 // more items than preferred load factor or
455 // more dead items than water mark.
456 if ((dead_factor > load_factor) ||
457 (load_factor > PREF_AVG_LIST_LEN) ||
458 (dead_factor > CLEAN_DEAD_HIGH_WATER_MARK)) {
459 log_debug(stringtable)("Concurrent work triggered, live factor: %g dead factor: %g",
460 load_factor, dead_factor);
461 _uncleaned_items_count = 0;
462 trigger_concurrent_work();
463 }
464 }
465
466 void StringTable::do_concurrent_work(JavaThread* jt) {
467 _has_work = false;
468 double load_factor = get_load_factor();
469 log_debug(stringtable, perf)("Concurrent work, live factor: %g", load_factor);
470 // We prefer growing, since that also removes dead items
471 if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
472 grow(jt);
473 } else {
474 clean_dead_entries(jt);
475 }
476 }
477
478 // Rehash
479 bool StringTable::do_rehash() {
480 if (!_local_table->is_safepoint_safe()) {
481 return false;
482 }
483
484 // We use current size, not max size.
485 size_t new_size = _local_table->get_size_log2(Thread::current());
486 StringTableHash* new_table = new StringTableHash(new_size, END_SIZE, REHASH_LEN);
487 // Use alt hash from now on
488 _alt_hash = true;
489 if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) {
490 _alt_hash = false;
491 delete new_table;
492 return false;
493 }
494
495 // free old table
496 delete _local_table;
497 _local_table = new_table;
498
499 return true;
500 }
501
502 void StringTable::rehash_table() {
503 static bool rehashed = false;
504 log_debug(stringtable)("Table imbalanced, rehashing called.");
505
506 // Grow instead of rehash.
507 if (get_load_factor() > PREF_AVG_LIST_LEN &&
508 !_local_table->is_max_size_reached()) {
509 log_debug(stringtable)("Choosing growing over rehashing.");
510 trigger_concurrent_work();
511 _needs_rehashing = false;
512 return;
513 }
514 // Already rehashed.
515 if (rehashed) {
516 log_warning(stringtable)("Rehashing already done, still long lists.");
517 trigger_concurrent_work();
518 _needs_rehashing = false;
519 return;
520 }
521
522 murmur_seed = AltHashing::compute_seed();
523 {
524 if (do_rehash()) {
525 rehashed = true;
526 } else {
527 log_info(stringtable)("Resizes in progress rehashing skipped.");
528 }
529 }
530 _needs_rehashing = false;
531 }
532
533 // Statistics
534 static int literal_size(oop obj) {
535 // NOTE: this would over-count if (pre-JDK8)
536 // java_lang_Class::has_offset_field() is true and the String.value array is
537 // shared by several Strings. However, starting from JDK8, the String.value
538 // array is not shared anymore.
539 if (obj == NULL) {
540 return 0;
541 } else if (obj->klass() == SystemDictionary::String_klass()) {
542 return (obj->size() + java_lang_String::value(obj)->size()) * HeapWordSize;
543 } else {
544 return obj->size();
545 }
546 }
547
548 struct SizeFunc : StackObj {
549 size_t operator()(WeakHandle* val) {
550 oop s = val->peek();
551 if (s == NULL) {
552 // Dead
553 return 0;
554 }
555 return literal_size(s);
556 };
557 };
558
559 TableStatistics StringTable::get_table_statistics() {
560 static TableStatistics ts;
561 SizeFunc sz;
562 ts = _local_table->statistics_get(Thread::current(), sz, ts);
563 return ts;
564 }
565
566 void StringTable::print_table_statistics(outputStream* st,
567 const char* table_name) {
568 SizeFunc sz;
569 _local_table->statistics_to(Thread::current(), sz, st, table_name);
570 }
571
572 // Verification
573 class VerifyStrings : StackObj {
574 public:
575 bool operator()(WeakHandle* val) {
576 oop s = val->peek();
577 if (s != NULL) {
578 assert(java_lang_String::length(s) >= 0, "Length on string must work.");
579 }
580 return true;
581 };
582 };
583
584 // This verification is part of Universe::verify() and needs to be quick.
585 void StringTable::verify() {
586 Thread* thr = Thread::current();
587 VerifyStrings vs;
588 if (!_local_table->try_scan(thr, vs)) {
589 log_info(stringtable)("verify unavailable at this moment");
590 }
591 }
592
593 // Verification and comp
594 class VerifyCompStrings : StackObj {
595 GrowableArray<oop>* _oops;
596 public:
597 size_t _errors;
598 VerifyCompStrings(GrowableArray<oop>* oops) : _oops(oops), _errors(0) {}
599 bool operator()(WeakHandle* val) {
600 oop s = val->resolve();
601 if (s == NULL) {
602 return true;
603 }
604 int len = _oops->length();
605 for (int i = 0; i < len; i++) {
606 bool eq = java_lang_String::equals(s, _oops->at(i));
607 assert(!eq, "Duplicate strings");
608 if (eq) {
609 _errors++;
610 }
611 }
612 _oops->push(s);
613 return true;
614 };
615 };
616
617 size_t StringTable::verify_and_compare_entries() {
618 Thread* thr = Thread::current();
619 GrowableArray<oop>* oops =
620 new (ResourceObj::C_HEAP, mtInternal)
621 GrowableArray<oop>((int)_current_size, mtInternal);
622
623 VerifyCompStrings vcs(oops);
624 if (!_local_table->try_scan(thr, vcs)) {
625 log_info(stringtable)("verify unavailable at this moment");
626 }
627 delete oops;
628 return vcs._errors;
629 }
630
631 // Dumping
632 class PrintString : StackObj {
633 Thread* _thr;
634 outputStream* _st;
635 public:
636 PrintString(Thread* thr, outputStream* st) : _thr(thr), _st(st) {}
637 bool operator()(WeakHandle* val) {
638 oop s = val->peek();
639 if (s == NULL) {
640 return true;
641 }
642 typeArrayOop value = java_lang_String::value_no_keepalive(s);
643 int length = java_lang_String::length(s);
644 bool is_latin1 = java_lang_String::is_latin1(s);
645
646 if (length <= 0) {
647 _st->print("%d: ", length);
648 } else {
649 ResourceMark rm(_thr);
650 int utf8_length = length;
651 char* utf8_string;
652
653 if (!is_latin1) {
654 jchar* chars = value->char_at_addr(0);
655 utf8_string = UNICODE::as_utf8(chars, utf8_length);
656 } else {
657 jbyte* bytes = value->byte_at_addr(0);
658 utf8_string = UNICODE::as_utf8(bytes, utf8_length);
659 }
660
661 _st->print("%d: ", utf8_length);
662 HashtableTextDump::put_utf8(_st, utf8_string, utf8_length);
663 }
664 _st->cr();
665 return true;
666 };
667 };
668
669 void StringTable::dump(outputStream* st, bool verbose) {
670 if (!verbose) {
671 print_table_statistics(st, "StringTable");
672 } else {
673 Thread* thr = Thread::current();
674 ResourceMark rm(thr);
675 st->print_cr("VERSION: 1.1");
676 PrintString ps(thr, st);
677 if (!_local_table->try_scan(thr, ps)) {
678 st->print_cr("dump unavailable at this moment");
679 }
680 }
681 }
682
683 // Utility for dumping strings
684 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
685 DCmdWithParser(output, heap),
686 _verbose("-verbose", "Dump the content of each string in the table",
687 "BOOLEAN", false, "false") {
688 _dcmdparser.add_dcmd_option(&_verbose);
689 }
690
691 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
692 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
693 _verbose.value());
694 VMThread::execute(&dumper);
695 }
696
697 int StringtableDCmd::num_arguments() {
698 ResourceMark rm;
699 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
700 if (dcmd != NULL) {
701 DCmdMark mark(dcmd);
702 return dcmd->_dcmdparser.num_arguments();
703 } else {
704 return 0;
705 }
706 }
707
708 // Sharing
709 #if INCLUDE_CDS_JAVA_HEAP
710 oop StringTable::lookup_shared(const jchar* name, int len, unsigned int hash) {
711 assert(hash == java_lang_String::hash_code(name, len),
712 "hash must be computed using java_lang_String::hash_code");
713 return _shared_table.lookup(name, hash, len);
714 }
715
716 oop StringTable::create_archived_string(oop s, Thread* THREAD) {
717 assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
718
719 if (HeapShared::is_archived_object(s)) {
720 return s;
721 }
722
723 oop new_s = NULL;
724 typeArrayOop v = java_lang_String::value_no_keepalive(s);
725 typeArrayOop new_v = (typeArrayOop)HeapShared::archive_heap_object(v, THREAD);
726 if (new_v == NULL) {
727 return NULL;
728 }
729 new_s = HeapShared::archive_heap_object(s, THREAD);
730 if (new_s == NULL) {
731 return NULL;
732 }
733
734 // adjust the pointer to the 'value' field in the new String oop
735 java_lang_String::set_value_raw(new_s, new_v);
736 return new_s;
737 }
738
739 struct CopyToArchive : StackObj {
740 CompactHashtableWriter* _writer;
741 CopyToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
742 bool operator()(WeakHandle* val) {
743 oop s = val->peek();
744 if (s == NULL) {
745 return true;
746 }
747 unsigned int hash = java_lang_String::hash_code(s);
748 oop new_s = StringTable::create_archived_string(s, Thread::current());
749 if (new_s == NULL) {
750 return true;
751 }
752
753 val->replace(new_s);
754 // add to the compact table
755 _writer->add(hash, CompressedOops::encode(new_s));
756 return true;
757 }
758 };
759
760 void StringTable::copy_shared_string_table(CompactHashtableWriter* writer) {
761 assert(HeapShared::is_heap_object_archiving_allowed(), "must be");
762
763 CopyToArchive copy(writer);
764 _local_table->do_safepoint_scan(copy);
765 }
766
767 void StringTable::write_to_archive() {
768 assert(HeapShared::is_heap_object_archiving_allowed(), "must be");
769
770 _shared_table.reset();
771 CompactHashtableWriter writer(_items_count, &MetaspaceShared::stats()->string);
772
773 // Copy the interned strings into the "string space" within the java heap
774 copy_shared_string_table(&writer);
775 writer.dump(&_shared_table, "string");
776 }
777
778 void StringTable::serialize_shared_table_header(SerializeClosure* soc) {
779 _shared_table.serialize_header(soc);
780
781 if (soc->writing()) {
782 // Sanity. Make sure we don't use the shared table at dump time
783 _shared_table.reset();
784 } else if (!HeapShared::closed_archive_heap_region_mapped()) {
785 _shared_table.reset();
786 }
787 }
788
789 class SharedStringIterator {
790 OopClosure* _oop_closure;
791 public:
792 SharedStringIterator(OopClosure* f) : _oop_closure(f) {}
793 void do_value(oop string) {
794 _oop_closure->do_oop(&string);
795 }
796 };
797
798 void StringTable::shared_oops_do(OopClosure* f) {
799 SharedStringIterator iter(f);
800 _shared_table.iterate(&iter);
801 }
802 #endif //INCLUDE_CDS_JAVA_HEAP