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 "logging/log.hpp"
34#include "logging/logStream.hpp"
35#include "memory/allocation.inline.hpp"
36#include "memory/filemap.hpp"
37#include "memory/heapShared.inline.hpp"
38#include "memory/resourceArea.hpp"
39#include "memory/universe.hpp"
40#include "oops/access.inline.hpp"
41#include "oops/compressedOops.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#include "utilities/utf8.hpp"
56
57// We prefer short chains of avg 2
58const double PREF_AVG_LIST_LEN = 2.0;
59// 2^24 is max size
60const size_t END_SIZE = 24;
61// If a chain gets to 100 something might be wrong
62const size_t REHASH_LEN = 100;
63// If we have as many dead items as 50% of the number of bucket
64const double CLEAN_DEAD_HIGH_WATER_MARK = 0.5;
65
66#if INCLUDE_CDS_JAVA_HEAP
67inline 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
73static CompactHashtable<
74 const jchar*, oop,
75 read_string_from_compact_hashtable,
76 java_lang_String::equals
77> _shared_table;
78#endif
79
80// --------------------------------------------------------------------------
81
82typedef ConcurrentHashTable<WeakHandle<vm_string_table_data>,
83 StringTableConfig, mtSymbol> StringTableHash;
84static StringTableHash* _local_table = NULL;
85
86volatile bool StringTable::_has_work = false;
87volatile bool StringTable::_needs_rehashing = false;
88
89volatile size_t StringTable::_uncleaned_items_count = 0;
90OopStorage* StringTable::_weak_handles = NULL;
91
92static size_t _current_size = 0;
93static volatile size_t _items_count = 0;
94
95volatile bool _alt_hash = false;
96static juint murmur_seed = 0;
97
98uintx hash_string(const jchar* s, int len, bool useAlt) {
99 return useAlt ?
100 AltHashing::murmur3_32(murmur_seed, s, len) :
101 java_lang_String::hash_code(s, len);
102}
103
104class StringTableConfig : public StringTableHash::BaseConfig {
105 private:
106 public:
107 static uintx get_hash(WeakHandle<vm_string_table_data> const& value,
108 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,
128 WeakHandle<vm_string_table_data> const& value) {
129 StringTable::item_added();
130 return StringTableHash::BaseConfig::allocate_node(size, value);
131 }
132 static void free_node(void* memory,
133 WeakHandle<vm_string_table_data> const& value) {
134 value.release();
135 StringTableHash::BaseConfig::free_node(memory, value);
136 StringTable::item_removed();
137 }
138};
139
140class StringTableLookupJchar : StackObj {
141 private:
142 Thread* _thread;
143 uintx _hash;
144 int _len;
145 const jchar* _str;
146 Handle _found;
147
148 public:
149 StringTableLookupJchar(Thread* thread, uintx hash, const jchar* key, int len)
150 : _thread(thread), _hash(hash), _len(len), _str(key) {
151 }
152 uintx get_hash() const {
153 return _hash;
154 }
155 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
156 oop val_oop = value->peek();
157 if (val_oop == NULL) {
158 // dead oop, mark this hash dead for cleaning
159 *is_dead = true;
160 return false;
161 }
162 bool equals = java_lang_String::equals(val_oop, _str, _len);
163 if (!equals) {
164 return false;
165 }
166 // Need to resolve weak handle and Handleize through possible safepoint.
167 _found = Handle(_thread, value->resolve());
168 return true;
169 }
170};
171
172class StringTableLookupOop : public StackObj {
173 private:
174 Thread* _thread;
175 uintx _hash;
176 Handle _find;
177 Handle _found; // Might be a different oop with the same value that's already
178 // in the table, which is the point.
179 public:
180 StringTableLookupOop(Thread* thread, uintx hash, Handle handle)
181 : _thread(thread), _hash(hash), _find(handle) { }
182
183 uintx get_hash() const {
184 return _hash;
185 }
186
187 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
188 oop val_oop = value->peek();
189 if (val_oop == NULL) {
190 // dead oop, mark this hash dead for cleaning
191 *is_dead = true;
192 return false;
193 }
194 bool equals = java_lang_String::equals(_find(), val_oop);
195 if (!equals) {
196 return false;
197 }
198 // Need to resolve weak handle and Handleize through possible safepoint.
199 _found = Handle(_thread, value->resolve());
200 return true;
201 }
202};
203
204static size_t ceil_log2(size_t val) {
205 size_t ret;
206 for (ret = 1; ((size_t)1 << ret) < val; ++ret);
207 return ret;
208}
209
210void StringTable::create_table() {
211 _weak_handles = new OopStorage("StringTable weak",
212 StringTableWeakAlloc_lock,
213 StringTableWeakActive_lock);
214 size_t start_size_log_2 = ceil_log2(StringTableSize);
215 _current_size = ((size_t)1) << start_size_log_2;
216 log_trace(stringtable)("Start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
217 _current_size, start_size_log_2);
218 _local_table = new StringTableHash(start_size_log_2, END_SIZE, REHASH_LEN);
219}
220
221size_t StringTable::item_added() {
222 return Atomic::add((size_t)1, &_items_count);
223}
224
225size_t StringTable::add_items_to_clean(size_t ndead) {
226 size_t total = Atomic::add((size_t)ndead, &_uncleaned_items_count);
227 log_trace(stringtable)(
228 "Uncleaned items:" SIZE_FORMAT " added: " SIZE_FORMAT " total:" SIZE_FORMAT,
229 _uncleaned_items_count, ndead, total);
230 return total;
231}
232
233void StringTable::item_removed() {
234 Atomic::add((size_t)-1, &_items_count);
235}
236
237double StringTable::get_load_factor() {
238 return (double)_items_count/_current_size;
239}
240
241double StringTable::get_dead_factor() {
242 return (double)_uncleaned_items_count/_current_size;
243}
244
245size_t StringTable::table_size() {
246 return ((size_t)1) << _local_table->get_size_log2(Thread::current());
247}
248
249void StringTable::trigger_concurrent_work() {
250 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
251 _has_work = true;
252 Service_lock->notify_all();
253}
254
255// Probing
256oop StringTable::lookup(Symbol* symbol) {
257 ResourceMark rm;
258 int length;
259 jchar* chars = symbol->as_unicode(length);
260 return lookup(chars, length);
261}
262
263oop StringTable::lookup(const jchar* name, int len) {
264 unsigned int hash = java_lang_String::hash_code(name, len);
265 oop string = lookup_shared(name, len, hash);
266 if (string != NULL) {
267 return string;
268 }
269 if (_alt_hash) {
270 hash = hash_string(name, len, true);
271 }
272 return do_lookup(name, len, hash);
273}
274
275class StringTableGet : public StackObj {
276 Thread* _thread;
277 Handle _return;
278 public:
279 StringTableGet(Thread* thread) : _thread(thread) {}
280 void operator()(WeakHandle<vm_string_table_data>* val) {
281 oop result = val->resolve();
282 assert(result != NULL, "Result should be reachable");
283 _return = Handle(_thread, result);
284 }
285 oop get_res_oop() {
286 return _return();
287 }
288};
289
290oop StringTable::do_lookup(const jchar* name, int len, uintx hash) {
291 Thread* thread = Thread::current();
292 StringTableLookupJchar lookup(thread, hash, name, len);
293 StringTableGet stg(thread);
294 bool rehash_warning;
295 _local_table->get(thread, lookup, stg, &rehash_warning);
296 update_needs_rehash(rehash_warning);
297 return stg.get_res_oop();
298}
299
300// Interning
301oop StringTable::intern(Symbol* symbol, TRAPS) {
302 if (symbol == NULL) return NULL;
303 ResourceMark rm(THREAD);
304 int length;
305 jchar* chars = symbol->as_unicode(length);
306 Handle string;
307 oop result = intern(string, chars, length, CHECK_NULL);
308 return result;
309}
310
311oop StringTable::intern(oop string, TRAPS) {
312 if (string == NULL) return NULL;
313 ResourceMark rm(THREAD);
314 int length;
315 Handle h_string (THREAD, string);
316 jchar* chars = java_lang_String::as_unicode_string(string, length,
317 CHECK_NULL);
318 oop result = intern(h_string, chars, length, CHECK_NULL);
319 return result;
320}
321
322oop StringTable::intern(const char* utf8_string, TRAPS) {
323 if (utf8_string == NULL) return NULL;
324 ResourceMark rm(THREAD);
325 int length = UTF8::unicode_length(utf8_string);
326 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
327 UTF8::convert_to_unicode(utf8_string, chars, length);
328 Handle string;
329 oop result = intern(string, chars, length, CHECK_NULL);
330 return result;
331}
332
333oop StringTable::intern(Handle string_or_null_h, const jchar* name, int len, TRAPS) {
334 // shared table always uses java_lang_String::hash_code
335 unsigned int hash = java_lang_String::hash_code(name, len);
336 oop found_string = lookup_shared(name, len, hash);
337 if (found_string != NULL) {
338 return found_string;
339 }
340 if (_alt_hash) {
341 hash = hash_string(name, len, true);
342 }
343 found_string = do_lookup(name, len, hash);
344 if (found_string != NULL) {
345 return found_string;
346 }
347 return do_intern(string_or_null_h, name, len, hash, CHECK_NULL);
348}
349
350oop StringTable::do_intern(Handle string_or_null_h, const jchar* name,
351 int len, uintx hash, TRAPS) {
352 HandleMark hm(THREAD); // cleanup strings created
353 Handle string_h;
354
355 if (!string_or_null_h.is_null()) {
356 string_h = string_or_null_h;
357 } else {
358 string_h = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
359 }
360
361 // Deduplicate the string before it is interned. Note that we should never
362 // deduplicate a string after it has been interned. Doing so will counteract
363 // compiler optimizations done on e.g. interned string literals.
364 Universe::heap()->deduplicate_string(string_h());
365
366 assert(java_lang_String::equals(string_h(), name, len),
367 "string must be properly initialized");
368 assert(len == java_lang_String::length(string_h()), "Must be same length");
369
370 StringTableLookupOop lookup(THREAD, hash, string_h);
371 StringTableGet stg(THREAD);
372
373 bool rehash_warning;
374 do {
375 // Callers have already looked up the String using the jchar* name, so just go to add.
376 WeakHandle<vm_string_table_data> wh = WeakHandle<vm_string_table_data>::create(string_h);
377 // The hash table takes ownership of the WeakHandle, even if it's not inserted.
378 if (_local_table->insert(THREAD, lookup, wh, &rehash_warning)) {
379 update_needs_rehash(rehash_warning);
380 return wh.resolve();
381 }
382 // In case another thread did a concurrent add, return value already in the table.
383 // This could fail if the String got gc'ed concurrently, so loop back until success.
384 if (_local_table->get(THREAD, lookup, stg, &rehash_warning)) {
385 update_needs_rehash(rehash_warning);
386 return stg.get_res_oop();
387 }
388 } while(true);
389}
390
391void StringTable::oops_do(OopClosure* f) {
392 assert(f != NULL, "No closure");
393 _weak_handles->oops_do(f);
394}
395
396// Concurrent work
397void StringTable::grow(JavaThread* jt) {
398 StringTableHash::GrowTask gt(_local_table);
399 if (!gt.prepare(jt)) {
400 return;
401 }
402 log_trace(stringtable)("Started to grow");
403 {
404 TraceTime timer("Grow", TRACETIME_LOG(Debug, stringtable, perf));
405 while (gt.do_task(jt)) {
406 gt.pause(jt);
407 {
408 ThreadBlockInVM tbivm(jt);
409 }
410 gt.cont(jt);
411 }
412 }
413 gt.done(jt);
414 _current_size = table_size();
415 log_debug(stringtable)("Grown to size:" SIZE_FORMAT, _current_size);
416}
417
418struct StringTableDoDelete : StackObj {
419 void operator()(WeakHandle<vm_string_table_data>* val) {
420 /* do nothing */
421 }
422};
423
424struct StringTableDeleteCheck : StackObj {
425 long _count;
426 long _item;
427 StringTableDeleteCheck() : _count(0), _item(0) {}
428 bool operator()(WeakHandle<vm_string_table_data>* val) {
429 ++_item;
430 oop tmp = val->peek();
431 if (tmp == NULL) {
432 ++_count;
433 return true;
434 } else {
435 return false;
436 }
437 }
438};
439
440void StringTable::clean_dead_entries(JavaThread* jt) {
441 StringTableHash::BulkDeleteTask bdt(_local_table);
442 if (!bdt.prepare(jt)) {
443 return;
444 }
445
446 StringTableDeleteCheck stdc;
447 StringTableDoDelete stdd;
448 {
449 TraceTime timer("Clean", TRACETIME_LOG(Debug, stringtable, perf));
450 while(bdt.do_task(jt, stdc, stdd)) {
451 bdt.pause(jt);
452 {
453 ThreadBlockInVM tbivm(jt);
454 }
455 bdt.cont(jt);
456 }
457 bdt.done(jt);
458 }
459 log_debug(stringtable)("Cleaned %ld of %ld", stdc._count, stdc._item);
460}
461
462void StringTable::check_concurrent_work() {
463 if (_has_work) {
464 return;
465 }
466
467 double load_factor = StringTable::get_load_factor();
468 double dead_factor = StringTable::get_dead_factor();
469 // We should clean/resize if we have more dead than alive,
470 // more items than preferred load factor or
471 // more dead items than water mark.
472 if ((dead_factor > load_factor) ||
473 (load_factor > PREF_AVG_LIST_LEN) ||
474 (dead_factor > CLEAN_DEAD_HIGH_WATER_MARK)) {
475 log_debug(stringtable)("Concurrent work triggered, live factor: %g dead factor: %g",
476 load_factor, dead_factor);
477 trigger_concurrent_work();
478 }
479}
480
481void StringTable::do_concurrent_work(JavaThread* jt) {
482 _has_work = false;
483 double load_factor = get_load_factor();
484 log_debug(stringtable, perf)("Concurrent work, live factor: %g", load_factor);
485 // We prefer growing, since that also removes dead items
486 if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
487 grow(jt);
488 } else {
489 clean_dead_entries(jt);
490 }
491}
492
493// Rehash
494bool StringTable::do_rehash() {
495 if (!_local_table->is_safepoint_safe()) {
496 return false;
497 }
498
499 // We use current size, not max size.
500 size_t new_size = _local_table->get_size_log2(Thread::current());
501 StringTableHash* new_table = new StringTableHash(new_size, END_SIZE, REHASH_LEN);
502 // Use alt hash from now on
503 _alt_hash = true;
504 if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) {
505 _alt_hash = false;
506 delete new_table;
507 return false;
508 }
509
510 // free old table
511 delete _local_table;
512 _local_table = new_table;
513
514 return true;
515}
516
517void StringTable::rehash_table() {
518 static bool rehashed = false;
519 log_debug(stringtable)("Table imbalanced, rehashing called.");
520
521 // Grow instead of rehash.
522 if (get_load_factor() > PREF_AVG_LIST_LEN &&
523 !_local_table->is_max_size_reached()) {
524 log_debug(stringtable)("Choosing growing over rehashing.");
525 trigger_concurrent_work();
526 _needs_rehashing = false;
527 return;
528 }
529 // Already rehashed.
530 if (rehashed) {
531 log_warning(stringtable)("Rehashing already done, still long lists.");
532 trigger_concurrent_work();
533 _needs_rehashing = false;
534 return;
535 }
536
537 murmur_seed = AltHashing::compute_seed();
538 {
539 if (do_rehash()) {
540 rehashed = true;
541 } else {
542 log_info(stringtable)("Resizes in progress rehashing skipped.");
543 }
544 }
545 _needs_rehashing = false;
546}
547
548// Statistics
549static int literal_size(oop obj) {
550 // NOTE: this would over-count if (pre-JDK8)
551 // java_lang_Class::has_offset_field() is true and the String.value array is
552 // shared by several Strings. However, starting from JDK8, the String.value
553 // array is not shared anymore.
554 if (obj == NULL) {
555 return 0;
556 } else if (obj->klass() == SystemDictionary::String_klass()) {
557 return (obj->size() + java_lang_String::value(obj)->size()) * HeapWordSize;
558 } else {
559 return obj->size();
560 }
561}
562
563struct SizeFunc : StackObj {
564 size_t operator()(WeakHandle<vm_string_table_data>* val) {
565 oop s = val->peek();
566 if (s == NULL) {
567 // Dead
568 return 0;
569 }
570 return literal_size(s);
571 };
572};
573
574TableStatistics StringTable::get_table_statistics() {
575 static TableStatistics ts;
576 SizeFunc sz;
577 ts = _local_table->statistics_get(Thread::current(), sz, ts);
578 return ts;
579}
580
581void StringTable::print_table_statistics(outputStream* st,
582 const char* table_name) {
583 SizeFunc sz;
584 _local_table->statistics_to(Thread::current(), sz, st, table_name);
585}
586
587// Verification
588class VerifyStrings : StackObj {
589 public:
590 bool operator()(WeakHandle<vm_string_table_data>* val) {
591 oop s = val->peek();
592 if (s != NULL) {
593 assert(java_lang_String::length(s) >= 0, "Length on string must work.");
594 }
595 return true;
596 };
597};
598
599// This verification is part of Universe::verify() and needs to be quick.
600void StringTable::verify() {
601 Thread* thr = Thread::current();
602 VerifyStrings vs;
603 if (!_local_table->try_scan(thr, vs)) {
604 log_info(stringtable)("verify unavailable at this moment");
605 }
606}
607
608// Verification and comp
609class VerifyCompStrings : StackObj {
610 GrowableArray<oop>* _oops;
611 public:
612 size_t _errors;
613 VerifyCompStrings(GrowableArray<oop>* oops) : _oops(oops), _errors(0) {}
614 bool operator()(WeakHandle<vm_string_table_data>* val) {
615 oop s = val->resolve();
616 if (s == NULL) {
617 return true;
618 }
619 int len = _oops->length();
620 for (int i = 0; i < len; i++) {
621 bool eq = java_lang_String::equals(s, _oops->at(i));
622 assert(!eq, "Duplicate strings");
623 if (eq) {
624 _errors++;
625 }
626 }
627 _oops->push(s);
628 return true;
629 };
630};
631
632size_t StringTable::verify_and_compare_entries() {
633 Thread* thr = Thread::current();
634 GrowableArray<oop>* oops =
635 new (ResourceObj::C_HEAP, mtInternal)
636 GrowableArray<oop>((int)_current_size, true);
637
638 VerifyCompStrings vcs(oops);
639 if (!_local_table->try_scan(thr, vcs)) {
640 log_info(stringtable)("verify unavailable at this moment");
641 }
642 delete oops;
643 return vcs._errors;
644}
645
646// Dumping
647class PrintString : StackObj {
648 Thread* _thr;
649 outputStream* _st;
650 public:
651 PrintString(Thread* thr, outputStream* st) : _thr(thr), _st(st) {}
652 bool operator()(WeakHandle<vm_string_table_data>* val) {
653 oop s = val->peek();
654 if (s == NULL) {
655 return true;
656 }
657 typeArrayOop value = java_lang_String::value_no_keepalive(s);
658 int length = java_lang_String::length(s);
659 bool is_latin1 = java_lang_String::is_latin1(s);
660
661 if (length <= 0) {
662 _st->print("%d: ", length);
663 } else {
664 ResourceMark rm(_thr);
665 int utf8_length = length;
666 char* utf8_string;
667
668 if (!is_latin1) {
669 jchar* chars = value->char_at_addr(0);
670 utf8_string = UNICODE::as_utf8(chars, utf8_length);
671 } else {
672 jbyte* bytes = value->byte_at_addr(0);
673 utf8_string = UNICODE::as_utf8(bytes, utf8_length);
674 }
675
676 _st->print("%d: ", utf8_length);
677 HashtableTextDump::put_utf8(_st, utf8_string, utf8_length);
678 }
679 _st->cr();
680 return true;
681 };
682};
683
684void StringTable::dump(outputStream* st, bool verbose) {
685 if (!verbose) {
686 print_table_statistics(st, "StringTable");
687 } else {
688 Thread* thr = Thread::current();
689 ResourceMark rm(thr);
690 st->print_cr("VERSION: 1.1");
691 PrintString ps(thr, st);
692 if (!_local_table->try_scan(thr, ps)) {
693 st->print_cr("dump unavailable at this moment");
694 }
695 }
696}
697
698// Utility for dumping strings
699StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
700 DCmdWithParser(output, heap),
701 _verbose("-verbose", "Dump the content of each string in the table",
702 "BOOLEAN", false, "false") {
703 _dcmdparser.add_dcmd_option(&_verbose);
704}
705
706void StringtableDCmd::execute(DCmdSource source, TRAPS) {
707 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
708 _verbose.value());
709 VMThread::execute(&dumper);
710}
711
712int StringtableDCmd::num_arguments() {
713 ResourceMark rm;
714 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
715 if (dcmd != NULL) {
716 DCmdMark mark(dcmd);
717 return dcmd->_dcmdparser.num_arguments();
718 } else {
719 return 0;
720 }
721}
722
723// Sharing
724#if INCLUDE_CDS_JAVA_HEAP
725oop StringTable::lookup_shared(const jchar* name, int len, unsigned int hash) {
726 assert(hash == java_lang_String::hash_code(name, len),
727 "hash must be computed using java_lang_String::hash_code");
728 return _shared_table.lookup(name, hash, len);
729}
730
731oop StringTable::create_archived_string(oop s, Thread* THREAD) {
732 assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
733
734 if (HeapShared::is_archived_object(s)) {
735 return s;
736 }
737
738 oop new_s = NULL;
739 typeArrayOop v = java_lang_String::value_no_keepalive(s);
740 typeArrayOop new_v = (typeArrayOop)HeapShared::archive_heap_object(v, THREAD);
741 if (new_v == NULL) {
742 return NULL;
743 }
744 new_s = HeapShared::archive_heap_object(s, THREAD);
745 if (new_s == NULL) {
746 return NULL;
747 }
748
749 // adjust the pointer to the 'value' field in the new String oop
750 java_lang_String::set_value_raw(new_s, new_v);
751 return new_s;
752}
753
754struct CopyToArchive : StackObj {
755 CompactHashtableWriter* _writer;
756 CopyToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
757 bool operator()(WeakHandle<vm_string_table_data>* val) {
758 oop s = val->peek();
759 if (s == NULL) {
760 return true;
761 }
762 unsigned int hash = java_lang_String::hash_code(s);
763 oop new_s = StringTable::create_archived_string(s, Thread::current());
764 if (new_s == NULL) {
765 return true;
766 }
767
768 val->replace(new_s);
769 // add to the compact table
770 _writer->add(hash, CompressedOops::encode(new_s));
771 return true;
772 }
773};
774
775void StringTable::copy_shared_string_table(CompactHashtableWriter* writer) {
776 assert(HeapShared::is_heap_object_archiving_allowed(), "must be");
777
778 CopyToArchive copy(writer);
779 _local_table->do_safepoint_scan(copy);
780}
781
782void StringTable::write_to_archive() {
783 assert(HeapShared::is_heap_object_archiving_allowed(), "must be");
784
785 _shared_table.reset();
786 CompactHashtableWriter writer(_items_count, &MetaspaceShared::stats()->string);
787
788 // Copy the interned strings into the "string space" within the java heap
789 copy_shared_string_table(&writer);
790 writer.dump(&_shared_table, "string");
791}
792
793void StringTable::serialize_shared_table_header(SerializeClosure* soc) {
794 _shared_table.serialize_header(soc);
795
796 if (soc->writing()) {
797 // Sanity. Make sure we don't use the shared table at dump time
798 _shared_table.reset();
799 } else if (!HeapShared::closed_archive_heap_region_mapped()) {
800 _shared_table.reset();
801 }
802}
803
804class SharedStringIterator {
805 OopClosure* _oop_closure;
806public:
807 SharedStringIterator(OopClosure* f) : _oop_closure(f) {}
808 void do_value(oop string) {
809 _oop_closure->do_oop(&string);
810 }
811};
812
813void StringTable::shared_oops_do(OopClosure* f) {
814 SharedStringIterator iter(f);
815 _shared_table.iterate(&iter);
816}
817#endif //INCLUDE_CDS_JAVA_HEAP
818