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.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/heapShared.inline.hpp"
39 #include "memory/resourceArea.hpp"
40 #include "memory/universe.hpp"
41 #include "oops/access.inline.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "oops/typeArrayOop.inline.hpp"
44 #include "oops/weakHandle.inline.hpp"
45 #include "runtime/atomic.hpp"
46 #include "runtime/handles.inline.hpp"
47 #include "runtime/mutexLocker.hpp"
48 #include "runtime/safepointVerifiers.hpp"
49 #include "runtime/timerTrace.hpp"
50 #include "runtime/interfaceSupport.inline.hpp"
51 #include "services/diagnosticCommand.hpp"
52 #include "utilities/concurrentHashTable.inline.hpp"
53 #include "utilities/concurrentHashTableTasks.inline.hpp"
54 #include "utilities/macros.hpp"
55
56 // We prefer short chains of avg 2
57 #define PREF_AVG_LIST_LEN 2
58 // 2^24 is max size
59 #define END_SIZE 24
60 // If a chain gets to 32 something might be wrong
61 #define REHASH_LEN 32
62 // If we have as many dead items as 50% of the number of bucket
63 #define CLEAN_DEAD_HIGH_WATER_MARK 0.5
64
65 #if INCLUDE_CDS_JAVA_HEAP
66 inline oop read_string_from_compact_hashtable(address base_address, u4 offset) {
67 assert(sizeof(narrowOop) == sizeof(offset), "must be");
68 narrowOop v = (narrowOop)offset;
69 return HeapShared::decode_from_archive(v);
70 }
71
72 static CompactHashtable<
73 const jchar*, oop,
74 read_string_from_compact_hashtable,
75 java_lang_String::equals
76 > _shared_table;
77 #endif
78
79 // --------------------------------------------------------------------------
80 StringTable* StringTable::_the_table = NULL;
81 volatile bool StringTable::_shared_string_mapped = false;
82 volatile bool StringTable::_alt_hash = false;
83
84 static juint murmur_seed = 0;
85
86 uintx hash_string(const jchar* s, int len, bool useAlt) {
87 return useAlt ?
88 AltHashing::murmur3_32(murmur_seed, s, len) :
89 java_lang_String::hash_code(s, len);
90 }
91
92 class StringTableConfig : public StringTableHash::BaseConfig {
93 private:
94 public:
95 static uintx get_hash(WeakHandle<vm_string_table_data> const& value,
96 bool* is_dead) {
97 EXCEPTION_MARK;
98 oop val_oop = value.peek();
99 if (val_oop == NULL) {
100 *is_dead = true;
101 return 0;
102 }
103 *is_dead = false;
104 ResourceMark rm(THREAD);
105 // All String oops are hashed as unicode
106 int length;
107 jchar* chars = java_lang_String::as_unicode_string(val_oop, length, THREAD);
108 if (chars != NULL) {
109 return hash_string(chars, length, StringTable::_alt_hash);
110 }
111 vm_exit_out_of_memory(length, OOM_MALLOC_ERROR, "get hash from oop");
112 return 0;
113 }
114 // We use default allocation/deallocation but counted
115 static void* allocate_node(size_t size,
116 WeakHandle<vm_string_table_data> const& value) {
117 StringTable::item_added();
118 return StringTableHash::BaseConfig::allocate_node(size, value);
119 }
120 static void free_node(void* memory,
121 WeakHandle<vm_string_table_data> const& value) {
122 value.release();
123 StringTableHash::BaseConfig::free_node(memory, value);
124 StringTable::item_removed();
125 }
126 };
127
128 class StringTableLookupJchar : StackObj {
129 private:
130 Thread* _thread;
131 uintx _hash;
132 int _len;
133 const jchar* _str;
134 Handle _found;
135
136 public:
137 StringTableLookupJchar(Thread* thread, uintx hash, const jchar* key, int len)
138 : _thread(thread), _hash(hash), _len(len), _str(key) {
139 }
140 uintx get_hash() const {
141 return _hash;
142 }
143 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
144 oop val_oop = value->peek();
145 if (val_oop == NULL) {
146 // dead oop, mark this hash dead for cleaning
147 *is_dead = true;
148 return false;
149 }
150 bool equals = java_lang_String::equals(val_oop, _str, _len);
151 if (!equals) {
152 return false;
153 }
154 // Need to resolve weak handle and Handleize through possible safepoint.
155 _found = Handle(_thread, value->resolve());
156 return true;
157 }
158 };
159
160 class StringTableLookupOop : public StackObj {
161 private:
162 Thread* _thread;
163 uintx _hash;
164 Handle _find;
165 Handle _found; // Might be a different oop with the same value that's already
166 // in the table, which is the point.
167 public:
168 StringTableLookupOop(Thread* thread, uintx hash, Handle handle)
169 : _thread(thread), _hash(hash), _find(handle) { }
170
171 uintx get_hash() const {
172 return _hash;
173 }
174
175 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
176 oop val_oop = value->peek();
177 if (val_oop == NULL) {
178 // dead oop, mark this hash dead for cleaning
179 *is_dead = true;
180 return false;
181 }
182 bool equals = java_lang_String::equals(_find(), val_oop);
183 if (!equals) {
184 return false;
185 }
186 // Need to resolve weak handle and Handleize through possible safepoint.
187 _found = Handle(_thread, value->resolve());
188 return true;
189 }
190 };
191
192 static size_t ceil_log2(size_t val) {
193 size_t ret;
194 for (ret = 1; ((size_t)1 << ret) < val; ++ret);
195 return ret;
196 }
197
198 StringTable::StringTable() : _local_table(NULL), _current_size(0), _has_work(0),
199 _needs_rehashing(false), _weak_handles(NULL), _items_count(0), _uncleaned_items_count(0) {
200 _weak_handles = new OopStorage("StringTable weak",
201 StringTableWeakAlloc_lock,
202 StringTableWeakActive_lock);
203 size_t start_size_log_2 = ceil_log2(StringTableSize);
204 _current_size = ((size_t)1) << start_size_log_2;
205 log_trace(stringtable)("Start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
206 _current_size, start_size_log_2);
207 _local_table = new StringTableHash(start_size_log_2, END_SIZE, REHASH_LEN);
208 }
209
210 size_t StringTable::item_added() {
211 return Atomic::add((size_t)1, &(the_table()->_items_count));
212 }
213
214 size_t StringTable::add_items_count_to_clean(size_t ndead) {
215 size_t total = Atomic::add((size_t)ndead, &(the_table()->_uncleaned_items_count));
216 log_trace(stringtable)(
217 "Uncleaned items:" SIZE_FORMAT " added: " SIZE_FORMAT " total:" SIZE_FORMAT,
218 the_table()->_uncleaned_items_count, ndead, total);
219 return total;
220 }
221
222 void StringTable::item_removed() {
223 Atomic::add((size_t)-1, &(the_table()->_items_count));
224 }
225
226 double StringTable::get_load_factor() {
227 return (double)_items_count/_current_size;
228 }
229
230 double StringTable::get_dead_factor() {
231 return (double)_uncleaned_items_count/_current_size;
232 }
233
234 size_t StringTable::table_size() {
235 return ((size_t)1) << _local_table->get_size_log2(Thread::current());
236 }
237
238 void StringTable::trigger_concurrent_work() {
239 MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
240 the_table()->_has_work = true;
241 Service_lock->notify_all();
242 }
243
244 // Probing
245 oop StringTable::lookup(Symbol* symbol) {
246 ResourceMark rm;
247 int length;
248 jchar* chars = symbol->as_unicode(length);
249 return lookup(chars, length);
250 }
251
252 oop StringTable::lookup(const jchar* name, int len) {
253 unsigned int hash = java_lang_String::hash_code(name, len);
254 oop string = StringTable::the_table()->lookup_shared(name, len, hash);
255 if (string != NULL) {
256 return string;
257 }
258 if (StringTable::_alt_hash) {
259 hash = hash_string(name, len, true);
260 }
261 return StringTable::the_table()->do_lookup(name, len, hash);
262 }
263
264 class StringTableGet : public StackObj {
265 Thread* _thread;
266 Handle _return;
267 public:
268 StringTableGet(Thread* thread) : _thread(thread) {}
269 void operator()(WeakHandle<vm_string_table_data>* val) {
270 oop result = val->resolve();
271 assert(result != NULL, "Result should be reachable");
272 _return = Handle(_thread, result);
273 }
274 oop get_res_oop() {
275 return _return();
276 }
277 };
278
279 oop StringTable::do_lookup(const jchar* name, int len, uintx hash) {
280 Thread* thread = Thread::current();
281 StringTableLookupJchar lookup(thread, hash, name, len);
282 StringTableGet stg(thread);
283 bool rehash_warning;
284 _local_table->get(thread, lookup, stg, &rehash_warning);
285 if (rehash_warning) {
286 _needs_rehashing = true;
287 }
288 return stg.get_res_oop();
289 }
290
291 // Interning
292 oop StringTable::intern(Symbol* symbol, TRAPS) {
293 if (symbol == NULL) return NULL;
294 ResourceMark rm(THREAD);
295 int length;
296 jchar* chars = symbol->as_unicode(length);
297 Handle string;
298 oop result = intern(string, chars, length, CHECK_NULL);
299 return result;
300 }
301
302 oop StringTable::intern(oop string, TRAPS) {
303 if (string == NULL) return NULL;
304 ResourceMark rm(THREAD);
305 int length;
306 Handle h_string (THREAD, string);
307 jchar* chars = java_lang_String::as_unicode_string(string, length,
308 CHECK_NULL);
309 oop result = intern(h_string, chars, length, CHECK_NULL);
310 return result;
311 }
312
313 oop StringTable::intern(const char* utf8_string, TRAPS) {
314 if (utf8_string == NULL) return NULL;
315 ResourceMark rm(THREAD);
316 int length = UTF8::unicode_length(utf8_string);
317 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
318 UTF8::convert_to_unicode(utf8_string, chars, length);
319 Handle string;
320 oop result = intern(string, chars, length, CHECK_NULL);
321 return result;
322 }
323
324 oop StringTable::intern(Handle string_or_null_h, const jchar* name, int len, TRAPS) {
325 // shared table always uses java_lang_String::hash_code
326 unsigned int hash = java_lang_String::hash_code(name, len);
327 oop found_string = StringTable::the_table()->lookup_shared(name, len, hash);
328 if (found_string != NULL) {
329 return found_string;
330 }
331 if (StringTable::_alt_hash) {
332 hash = hash_string(name, len, true);
333 }
334 return StringTable::the_table()->do_intern(string_or_null_h, name, len,
335 hash, CHECK_NULL);
336 }
337
338 class StringTableCreateEntry : public StackObj {
339 private:
340 Thread* _thread;
341 Handle _return;
342 Handle _store;
343 public:
344 StringTableCreateEntry(Thread* thread, Handle store)
345 : _thread(thread), _store(store) {}
346
347 WeakHandle<vm_string_table_data> operator()() { // No dups found
348 WeakHandle<vm_string_table_data> wh =
349 WeakHandle<vm_string_table_data>::create(_store);
350 return wh;
351 }
352 void operator()(bool inserted, WeakHandle<vm_string_table_data>* val) {
353 oop result = val->resolve();
354 assert(result != NULL, "Result should be reachable");
355 _return = Handle(_thread, result);
356 }
357 oop get_return() const {
358 return _return();
359 }
360 };
361
362 oop StringTable::do_intern(Handle string_or_null_h, const jchar* name,
363 int len, uintx hash, TRAPS) {
364 HandleMark hm(THREAD); // cleanup strings created
365 Handle string_h;
366
367 if (!string_or_null_h.is_null()) {
368 string_h = string_or_null_h;
369 } else {
370 string_h = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
371 }
372
373 // Deduplicate the string before it is interned. Note that we should never
374 // deduplicate a string after it has been interned. Doing so will counteract
375 // compiler optimizations done on e.g. interned string literals.
376 Universe::heap()->deduplicate_string(string_h());
377
378 assert(java_lang_String::equals(string_h(), name, len),
379 "string must be properly initialized");
380 assert(len == java_lang_String::length(string_h()), "Must be same length");
381 StringTableLookupOop lookup(THREAD, hash, string_h);
382 StringTableCreateEntry stc(THREAD, string_h);
383
384 bool rehash_warning;
385 _local_table->get_insert_lazy(THREAD, lookup, stc, stc, &rehash_warning);
386 if (rehash_warning) {
387 _needs_rehashing = true;
388 }
389 return stc.get_return();
390 }
391
392 // GC support
393 class StringTableIsAliveCounter : public BoolObjectClosure {
394 BoolObjectClosure* _real_boc;
395 public:
396 size_t _count;
397 size_t _count_total;
398 StringTableIsAliveCounter(BoolObjectClosure* boc) : _real_boc(boc), _count(0),
399 _count_total(0) {}
400 bool do_object_b(oop obj) {
401 bool ret = _real_boc->do_object_b(obj);
402 if (!ret) {
403 ++_count;
404 }
405 ++_count_total;
406 return ret;
407 }
408 };
409
410 void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f,
411 size_t* processed, size_t* removed) {
412 DoNothingClosure dnc;
413 assert(is_alive != NULL, "No closure");
414 StringTableIsAliveCounter stiac(is_alive);
415 OopClosure* tmp = f != NULL ? f : &dnc;
416
417 StringTable::the_table()->_weak_handles->weak_oops_do(&stiac, tmp);
418
419 // This is the serial case without ParState.
420 // Just set the correct number and check for a cleaning phase.
421 the_table()->_uncleaned_items_count = stiac._count;
422 StringTable::the_table()->check_concurrent_work();
423
424 if (processed != NULL) {
425 *processed = stiac._count_total;
426 }
427 if (removed != NULL) {
428 *removed = stiac._count;
429 }
430 }
431
432 void StringTable::oops_do(OopClosure* f) {
433 assert(f != NULL, "No closure");
434 StringTable::the_table()->_weak_handles->oops_do(f);
435 }
436
437 void StringTable::possibly_parallel_unlink(
438 OopStorage::ParState<false, false>* _par_state_string, BoolObjectClosure* cl,
439 size_t* processed, size_t* removed)
440 {
441 DoNothingClosure dnc;
442 assert(cl != NULL, "No closure");
443 StringTableIsAliveCounter stiac(cl);
444
445 _par_state_string->weak_oops_do(&stiac, &dnc);
446
447 // Accumulate the dead strings.
448 the_table()->add_items_count_to_clean(stiac._count);
449
450 *processed = stiac._count_total;
451 *removed = stiac._count;
452 }
453
454 void StringTable::possibly_parallel_oops_do(
455 OopStorage::ParState<false /* concurrent */, false /* const */>*
456 _par_state_string, OopClosure* f)
457 {
458 assert(f != NULL, "No closure");
459 _par_state_string->oops_do(f);
460 }
461
462 // Concurrent work
463 void StringTable::grow(JavaThread* jt) {
464 StringTableHash::GrowTask gt(_local_table);
465 if (!gt.prepare(jt)) {
466 return;
467 }
468 log_trace(stringtable)("Started to grow");
469 {
470 TraceTime timer("Grow", TRACETIME_LOG(Debug, stringtable, perf));
471 while (gt.do_task(jt)) {
472 gt.pause(jt);
473 {
474 ThreadBlockInVM tbivm(jt);
475 }
476 gt.cont(jt);
477 }
478 }
479 gt.done(jt);
480 _current_size = table_size();
481 log_debug(stringtable)("Grown to size:" SIZE_FORMAT, _current_size);
482 }
483
484 struct StringTableDoDelete : StackObj {
485 void operator()(WeakHandle<vm_string_table_data>* val) {
486 /* do nothing */
487 }
488 };
489
490 struct StringTableDeleteCheck : StackObj {
491 long _count;
492 long _item;
493 StringTableDeleteCheck() : _count(0), _item(0) {}
494 bool operator()(WeakHandle<vm_string_table_data>* val) {
495 ++_item;
496 oop tmp = val->peek();
497 if (tmp == NULL) {
498 ++_count;
499 return true;
500 } else {
501 return false;
502 }
503 }
504 };
505
506 void StringTable::clean_dead_entries(JavaThread* jt) {
507 StringTableHash::BulkDeleteTask bdt(_local_table);
508 if (!bdt.prepare(jt)) {
509 return;
510 }
511
512 StringTableDeleteCheck stdc;
513 StringTableDoDelete stdd;
514 {
515 TraceTime timer("Clean", TRACETIME_LOG(Debug, stringtable, perf));
516 while(bdt.do_task(jt, stdc, stdd)) {
517 bdt.pause(jt);
518 {
519 ThreadBlockInVM tbivm(jt);
520 }
521 bdt.cont(jt);
522 }
523 bdt.done(jt);
524 }
525 log_debug(stringtable)("Cleaned %ld of %ld", stdc._count, stdc._item);
526 }
527
528 void StringTable::check_concurrent_work() {
529 if (_has_work) {
530 return;
531 }
532
533 double load_factor = StringTable::get_load_factor();
534 double dead_factor = StringTable::get_dead_factor();
535 // We should clean/resize if we have more dead than alive,
536 // more items than preferred load factor or
537 // more dead items than water mark.
538 if ((dead_factor > load_factor) ||
539 (load_factor > PREF_AVG_LIST_LEN) ||
540 (dead_factor > CLEAN_DEAD_HIGH_WATER_MARK)) {
541 log_debug(stringtable)("Concurrent work triggered, live factor:%g dead factor:%g",
542 load_factor, dead_factor);
543 trigger_concurrent_work();
544 }
545 }
546
547 void StringTable::concurrent_work(JavaThread* jt) {
548 _has_work = false;
549 double load_factor = get_load_factor();
550 log_debug(stringtable, perf)("Concurrent work, live factor: %g", load_factor);
551 // We prefer growing, since that also removes dead items
552 if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
553 grow(jt);
554 } else {
555 clean_dead_entries(jt);
556 }
557 }
558
559 void StringTable::do_concurrent_work(JavaThread* jt) {
560 StringTable::the_table()->concurrent_work(jt);
561 }
562
563 // Rehash
564 bool StringTable::do_rehash() {
565 if (!_local_table->is_safepoint_safe()) {
566 return false;
567 }
568
569 // We use max size
570 StringTableHash* new_table = new StringTableHash(END_SIZE, END_SIZE, REHASH_LEN);
571 // Use alt hash from now on
572 _alt_hash = true;
573 if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) {
574 _alt_hash = false;
575 delete new_table;
576 return false;
577 }
578
579 // free old table
580 delete _local_table;
581 _local_table = new_table;
582
583 return true;
584 }
585
586 void StringTable::try_rehash_table() {
587 static bool rehashed = false;
588 log_debug(stringtable)("Table imbalanced, rehashing called.");
589
590 // Grow instead of rehash.
591 if (get_load_factor() > PREF_AVG_LIST_LEN &&
592 !_local_table->is_max_size_reached()) {
593 log_debug(stringtable)("Choosing growing over rehashing.");
594 trigger_concurrent_work();
595 _needs_rehashing = false;
596 return;
597 }
598 // Already rehashed.
599 if (rehashed) {
600 log_warning(stringtable)("Rehashing already done, still long lists.");
601 trigger_concurrent_work();
602 _needs_rehashing = false;
603 return;
604 }
605
606 murmur_seed = AltHashing::compute_seed();
607 {
608 if (do_rehash()) {
609 rehashed = true;
610 } else {
611 log_info(stringtable)("Resizes in progress rehashing skipped.");
612 }
613 }
614 _needs_rehashing = false;
615 }
616
617 void StringTable::rehash_table() {
618 StringTable::the_table()->try_rehash_table();
619 }
620
621 // Statistics
622 static int literal_size(oop obj) {
623 // NOTE: this would over-count if (pre-JDK8)
624 // java_lang_Class::has_offset_field() is true and the String.value array is
625 // shared by several Strings. However, starting from JDK8, the String.value
626 // array is not shared anymore.
627 if (obj == NULL) {
628 return 0;
629 } else if (obj->klass() == SystemDictionary::String_klass()) {
630 return (obj->size() + java_lang_String::value(obj)->size()) * HeapWordSize;
631 } else {
632 return obj->size();
633 }
634 }
635
636 struct SizeFunc : StackObj {
637 size_t operator()(WeakHandle<vm_string_table_data>* val) {
638 oop s = val->peek();
639 if (s == NULL) {
640 // Dead
641 return 0;
642 }
643 return literal_size(s);
644 };
645 };
646
647 void StringTable::print_table_statistics(outputStream* st,
648 const char* table_name) {
649 SizeFunc sz;
650 _local_table->statistics_to(Thread::current(), sz, st, table_name);
651 }
652
653 // Verification
654 class VerifyStrings : StackObj {
655 public:
656 bool operator()(WeakHandle<vm_string_table_data>* val) {
657 oop s = val->peek();
658 if (s != NULL) {
659 assert(java_lang_String::length(s) >= 0, "Length on string must work.");
660 }
661 return true;
662 };
663 };
664
665 // This verification is part of Universe::verify() and needs to be quick.
666 void StringTable::verify() {
667 Thread* thr = Thread::current();
668 VerifyStrings vs;
669 if (!the_table()->_local_table->try_scan(thr, vs)) {
670 log_info(stringtable)("verify unavailable at this moment");
671 }
672 }
673
674 // Verification and comp
675 class VerifyCompStrings : StackObj {
676 GrowableArray<oop>* _oops;
677 public:
678 size_t _errors;
679 VerifyCompStrings(GrowableArray<oop>* oops) : _oops(oops), _errors(0) {}
680 bool operator()(WeakHandle<vm_string_table_data>* val) {
681 oop s = val->resolve();
682 if (s == NULL) {
683 return true;
684 }
685 int len = _oops->length();
686 for (int i = 0; i < len; i++) {
687 bool eq = java_lang_String::equals(s, _oops->at(i));
688 assert(!eq, "Duplicate strings");
689 if (eq) {
690 _errors++;
691 }
692 }
693 _oops->push(s);
694 return true;
695 };
696 };
697
698 size_t StringTable::verify_and_compare_entries() {
699 Thread* thr = Thread::current();
700 GrowableArray<oop>* oops =
701 new (ResourceObj::C_HEAP, mtInternal)
702 GrowableArray<oop>((int)the_table()->_current_size, true);
703
704 VerifyCompStrings vcs(oops);
705 if (!the_table()->_local_table->try_scan(thr, vcs)) {
706 log_info(stringtable)("verify unavailable at this moment");
707 }
708 delete oops;
709 return vcs._errors;
710 }
711
712 // Dumping
713 class PrintString : StackObj {
714 Thread* _thr;
715 outputStream* _st;
716 public:
717 PrintString(Thread* thr, outputStream* st) : _thr(thr), _st(st) {}
718 bool operator()(WeakHandle<vm_string_table_data>* val) {
719 oop s = val->peek();
720 if (s == NULL) {
721 return true;
722 }
723 typeArrayOop value = java_lang_String::value_no_keepalive(s);
724 int length = java_lang_String::length(s);
725 bool is_latin1 = java_lang_String::is_latin1(s);
726
727 if (length <= 0) {
728 _st->print("%d: ", length);
729 } else {
730 ResourceMark rm(_thr);
731 int utf8_length = length;
732 char* utf8_string;
733
734 if (!is_latin1) {
735 jchar* chars = value->char_at_addr(0);
736 utf8_string = UNICODE::as_utf8(chars, utf8_length);
737 } else {
738 jbyte* bytes = value->byte_at_addr(0);
739 utf8_string = UNICODE::as_utf8(bytes, utf8_length);
740 }
741
742 _st->print("%d: ", utf8_length);
743 HashtableTextDump::put_utf8(_st, utf8_string, utf8_length);
744 }
745 _st->cr();
746 return true;
747 };
748 };
749
750 void StringTable::dump(outputStream* st, bool verbose) {
751 if (!verbose) {
752 the_table()->print_table_statistics(st, "StringTable");
753 } else {
754 Thread* thr = Thread::current();
755 ResourceMark rm(thr);
756 st->print_cr("VERSION: 1.1");
757 PrintString ps(thr, st);
758 if (!the_table()->_local_table->try_scan(thr, ps)) {
759 st->print_cr("dump unavailable at this moment");
760 }
761 }
762 }
763
764 // Utility for dumping strings
765 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
766 DCmdWithParser(output, heap),
767 _verbose("-verbose", "Dump the content of each string in the table",
768 "BOOLEAN", false, "false") {
769 _dcmdparser.add_dcmd_option(&_verbose);
770 }
771
772 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
773 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
774 _verbose.value());
775 VMThread::execute(&dumper);
776 }
777
778 int StringtableDCmd::num_arguments() {
779 ResourceMark rm;
780 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
781 if (dcmd != NULL) {
782 DCmdMark mark(dcmd);
783 return dcmd->_dcmdparser.num_arguments();
784 } else {
785 return 0;
786 }
787 }
788
789 // Sharing
790 #if INCLUDE_CDS_JAVA_HEAP
791 oop StringTable::lookup_shared(const jchar* name, int len, unsigned int hash) {
792 assert(hash == java_lang_String::hash_code(name, len),
793 "hash must be computed using java_lang_String::hash_code");
794 return _shared_table.lookup(name, hash, len);
795 }
796
797 oop StringTable::create_archived_string(oop s, Thread* THREAD) {
798 assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
799
800 if (HeapShared::is_archived_object(s)) {
801 return s;
802 }
803
804 oop new_s = NULL;
805 typeArrayOop v = java_lang_String::value_no_keepalive(s);
806 typeArrayOop new_v = (typeArrayOop)HeapShared::archive_heap_object(v, THREAD);
807 if (new_v == NULL) {
808 return NULL;
809 }
810 new_s = HeapShared::archive_heap_object(s, THREAD);
811 if (new_s == NULL) {
812 return NULL;
813 }
814
815 // adjust the pointer to the 'value' field in the new String oop
816 java_lang_String::set_value_raw(new_s, new_v);
817 return new_s;
818 }
819
820 class CompactStringTableWriter: public CompactHashtableWriter {
821 public:
822 CompactStringTableWriter(int num_entries, CompactHashtableStats* stats) :
823 CompactHashtableWriter(num_entries, stats) {}
824 void add(unsigned int hash, oop string) {
825 CompactHashtableWriter::add(hash, CompressedOops::encode(string));
826 }
827 };
828
829 struct CopyToArchive : StackObj {
830 CompactStringTableWriter* _writer;
831 CopyToArchive(CompactStringTableWriter* writer) : _writer(writer) {}
832 bool operator()(WeakHandle<vm_string_table_data>* val) {
833 oop s = val->peek();
834 if (s == NULL) {
835 return true;
836 }
837 unsigned int hash = java_lang_String::hash_code(s);
838 if (hash == 0) {
839 return true;
840 }
841
842 java_lang_String::set_hash(s, hash);
843 oop new_s = StringTable::create_archived_string(s, Thread::current());
844 if (new_s == NULL) {
845 return true;
846 }
847
848 val->replace(new_s);
849 // add to the compact table
850 _writer->add(hash, new_s);
851 return true;
852 }
853 };
854
855 void StringTable::copy_shared_string_table(CompactStringTableWriter* writer) {
856 assert(HeapShared::is_heap_object_archiving_allowed(), "must be");
857
858 CopyToArchive copy(writer);
859 StringTable::the_table()->_local_table->do_scan(Thread::current(), copy);
860 }
861
862 void StringTable::write_to_archive() {
863 assert(HeapShared::is_heap_object_archiving_allowed(), "must be");
864
865 _shared_table.reset();
866 int num_buckets = the_table()->_items_count / SharedSymbolTableBucketSize;
867 // calculation of num_buckets can result in zero buckets, we need at least one
868 CompactStringTableWriter writer(num_buckets > 1 ? num_buckets : 1,
869 &MetaspaceShared::stats()->string);
870
871 // Copy the interned strings into the "string space" within the java heap
872 copy_shared_string_table(&writer);
873 writer.dump(&_shared_table, "string");
874 }
875
876 void StringTable::serialize(SerializeClosure* soc) {
877 _shared_table.serialize(soc);
878
879 if (soc->writing()) {
880 // Sanity. Make sure we don't use the shared table at dump time
881 _shared_table.reset();
882 } else if (!_shared_string_mapped) {
883 _shared_table.reset();
884 }
885 }
886
887 class SharedStringIterator {
888 OopClosure* _oop_closure;
889 public:
890 SharedStringIterator(OopClosure* f) : _oop_closure(f) {}
891 void do_value(oop string) {
892 _oop_closure->do_oop(&string);
893 }
894 };
895
896 void StringTable::shared_oops_do(OopClosure* f) {
897 SharedStringIterator iter(f);
898 _shared_table.iterate(&iter);
899 }
900 #endif //INCLUDE_CDS_JAVA_HEAP