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