1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/altHashing.hpp"
27 #include "classfile/compactHashtable.inline.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/stringTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "gc/shared/collectedHeap.hpp"
32 #include "gc/shared/oopStorage.inline.hpp"
33 #include "gc/shared/oopStorageParState.inline.hpp"
34 #include "logging/log.hpp"
35 #include "logging/logStream.hpp"
36 #include "memory/allocation.inline.hpp"
37 #include "memory/filemap.hpp"
38 #include "memory/metaspaceShared.hpp"
39 #include "memory/resourceArea.hpp"
40 #include "memory/universe.hpp"
41 #include "oops/access.inline.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "oops/typeArrayOop.inline.hpp"
44 #include "oops/weakHandle.inline.hpp"
45 #include "runtime/atomic.hpp"
46 #include "runtime/handles.inline.hpp"
47 #include "runtime/mutexLocker.hpp"
48 #include "runtime/safepointVerifiers.hpp"
49 #include "runtime/timerTrace.hpp"
50 #include "runtime/interfaceSupport.inline.hpp"
51 #include "services/diagnosticCommand.hpp"
52 #include "utilities/concurrentHashTable.inline.hpp"
53 #include "utilities/concurrentHashTableTasks.inline.hpp"
54 #include "utilities/macros.hpp"
55
56 // We prefer short chains of avg 2
57 #define PREF_AVG_LIST_LEN 2
58 // 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 // --------------------------------------------------------------------------
66 StringTable* StringTable::_the_table = NULL;
67 bool StringTable::_shared_string_mapped = false;
68 CompactHashtable<oop, char> StringTable::_shared_table;
69 bool StringTable::_alt_hash = false;
70
71 static juint murmur_seed = 0;
72
73 uintx hash_string(const jchar* s, int len, bool useAlt) {
74 return useAlt ?
75 AltHashing::murmur3_32(murmur_seed, s, len) :
76 java_lang_String::hash_code(s, len);
77 }
78
79 class StringTableConfig : public StringTableHash::BaseConfig {
80 private:
81 public:
82 static uintx get_hash(WeakHandle<vm_string_table_data> const& value,
83 bool* is_dead) {
84 EXCEPTION_MARK;
85 oop val_oop = value.peek();
86 if (val_oop == NULL) {
87 *is_dead = true;
88 return 0;
89 }
90 *is_dead = false;
91 ResourceMark rm(THREAD);
92 // All String oops are hashed as unicode
93 int length;
94 jchar* chars = java_lang_String::as_unicode_string(val_oop, length, THREAD);
95 if (chars != NULL) {
96 return hash_string(chars, length, StringTable::_alt_hash);
97 }
98 vm_exit_out_of_memory(length, OOM_MALLOC_ERROR, "get hash from oop");
99 return 0;
100 }
101 // We use default allocation/deallocation but counted
102 static void* allocate_node(size_t size,
103 WeakHandle<vm_string_table_data> const& value) {
104 StringTable::item_added();
105 return StringTableHash::BaseConfig::allocate_node(size, value);
106 }
107 static void free_node(void* memory,
108 WeakHandle<vm_string_table_data> const& value) {
109 value.release();
110 StringTableHash::BaseConfig::free_node(memory, value);
111 StringTable::item_removed();
112 }
113 };
114
115 class StringTableLookupJchar : StackObj {
116 private:
117 Thread* _thread;
118 uintx _hash;
119 int _len;
120 const jchar* _str;
121 Handle _found;
122
123 public:
124 StringTableLookupJchar(Thread* thread, uintx hash, const jchar* key, int len)
125 : _thread(thread), _hash(hash), _str(key), _len(len) {
126 }
127 uintx get_hash() const {
128 return _hash;
129 }
130 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
131 oop val_oop = value->peek();
132 if (val_oop == NULL) {
133 // dead oop, mark this hash dead for cleaning
134 *is_dead = true;
135 return false;
136 }
137 bool equals = java_lang_String::equals(val_oop, (jchar*)_str, _len);
138 if (!equals) {
139 return false;
140 }
141 // Need to resolve weak handle and Handleize through possible safepoint.
142 _found = Handle(_thread, value->resolve());
143 return true;
144 }
145 };
146
147 class StringTableLookupOop : public StackObj {
148 private:
149 Thread* _thread;
150 uintx _hash;
151 Handle _find;
152 Handle _found; // Might be a different oop with the same value that's already
153 // in the table, which is the point.
154 public:
155 StringTableLookupOop(Thread* thread, uintx hash, Handle handle)
156 : _thread(thread), _hash(hash), _find(handle) { }
157
158 uintx get_hash() const {
159 return _hash;
160 }
161
162 bool equals(WeakHandle<vm_string_table_data>* value, bool* is_dead) {
163 oop val_oop = value->peek();
164 if (val_oop == NULL) {
165 // dead oop, mark this hash dead for cleaning
166 *is_dead = true;
167 return false;
168 }
169 bool equals = java_lang_String::equals(_find(), val_oop);
170 if (!equals) {
171 return false;
172 }
173 // Need to resolve weak handle and Handleize through possible safepoint.
174 _found = Handle(_thread, value->resolve());
175 return true;
176 }
177 };
178
179 static size_t ceil_pow_2(uintx val) {
180 size_t ret;
181 for (ret = 1; ((size_t)1 << ret) < val; ++ret);
182 return ret;
183 }
184
185 StringTable::StringTable() : _local_table(NULL), _current_size(0), _has_work(0),
186 _needs_rehashing(false), _weak_handles(NULL), _items(0), _uncleaned_items(0) {
187 _weak_handles = new OopStorage("StringTable weak",
188 StringTableWeakAlloc_lock,
189 StringTableWeakActive_lock);
190 size_t start_size_log_2 = ceil_pow_2(StringTableSize);
191 _current_size = ((size_t)1) << start_size_log_2;
192 log_trace(stringtable)("Start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
193 _current_size, start_size_log_2);
194 _local_table = new StringTableHash(start_size_log_2, END_SIZE, REHASH_LEN);
195 }
196
197 size_t StringTable::item_added() {
198 return Atomic::add((size_t)1, &(the_table()->_items));
199 }
200
201 size_t StringTable::items_to_clean(size_t ncl) {
202 size_t total = Atomic::add((size_t)ncl, &(the_table()->_uncleaned_items));
203 log_trace(stringtable)(
204 "Uncleaned items:" SIZE_FORMAT " added: " SIZE_FORMAT " total:" SIZE_FORMAT,
205 the_table()->_uncleaned_items, ncl, total);
206 return total;
207 }
208
209 void StringTable::item_removed() {
210 Atomic::add((size_t)-1, &(the_table()->_items));
211 Atomic::add((size_t)-1, &(the_table()->_uncleaned_items));
212 }
213
214 double StringTable::get_load_factor() {
215 return (_items*1.0)/_current_size;
216 }
217
218 double StringTable::get_dead_factor() {
219 return (_uncleaned_items*1.0)/_current_size;
220 }
221
222 size_t StringTable::table_size(Thread* thread) {
223 return ((size_t)(1)) << _local_table->get_size_log2(thread != NULL ? thread
224 : Thread::current());
225 }
226
227 void StringTable::trigger_concurrent_work() {
228 MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
229 the_table()->_has_work = true;
230 Service_lock->notify_all();
231 }
232
233 // Probing
234 oop StringTable::lookup(Symbol* symbol) {
235 ResourceMark rm;
236 int length;
237 jchar* chars = symbol->as_unicode(length);
238 return lookup(chars, length);
239 }
240
241 oop StringTable::lookup(jchar* name, int len) {
242 unsigned int hash = java_lang_String::hash_code(name, len);
243 oop string = StringTable::the_table()->lookup_shared(name, len, hash);
244 if (string != NULL) {
245 return string;
246 }
247 if (StringTable::_alt_hash) {
248 hash = hash_string(name, len, true);
249 }
250 return StringTable::the_table()->do_lookup(name, len, hash);
251 }
252
253 class StringTableGet : public StackObj {
254 Thread* _thread;
255 Handle _return;
256 public:
257 StringTableGet(Thread* thread) : _thread(thread) {}
258 void operator()(WeakHandle<vm_string_table_data>* val) {
259 oop result = val->resolve();
260 assert(result != NULL, "Result should be reachable");
261 _return = Handle(_thread, result);
262 }
263 oop get_res_oop() {
264 return _return();
265 }
266 };
267
268 oop StringTable::do_lookup(jchar* name, int len, uintx hash) {
269 Thread* thread = Thread::current();
270 StringTableLookupJchar lookup(thread, hash, name, len);
271 StringTableGet stg(thread);
272 bool rehash_warning;
273 _local_table->get(thread, lookup, stg, &rehash_warning);
274 if (rehash_warning) {
275 _needs_rehashing = true;
276 }
277 return stg.get_res_oop();
278 }
279
280 // Interning
281 oop StringTable::intern(Symbol* symbol, TRAPS) {
282 if (symbol == NULL) return NULL;
283 ResourceMark rm(THREAD);
284 int length;
285 jchar* chars = symbol->as_unicode(length);
286 Handle string;
287 oop result = intern(string, chars, length, CHECK_NULL);
288 return result;
289 }
290
291 oop StringTable::intern(oop string, TRAPS) {
292 if (string == NULL) return NULL;
293 ResourceMark rm(THREAD);
294 int length;
295 Handle h_string (THREAD, string);
296 jchar* chars = java_lang_String::as_unicode_string(string, length,
297 CHECK_NULL);
298 oop result = intern(h_string, chars, length, CHECK_NULL);
299 return result;
300 }
301
302 oop StringTable::intern(const char* utf8_string, TRAPS) {
303 if (utf8_string == NULL) return NULL;
304 ResourceMark rm(THREAD);
305 int length = UTF8::unicode_length(utf8_string);
306 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
307 UTF8::convert_to_unicode(utf8_string, chars, length);
308 Handle string;
309 oop result = intern(string, chars, length, CHECK_NULL);
310 return result;
311 }
312
313 oop StringTable::intern(Handle string_or_null_h, jchar* name, int len, TRAPS) {
314 // shared table always uses java_lang_String::hash_code
315 unsigned int hash = java_lang_String::hash_code(name, len);
316 oop found_string = StringTable::the_table()->lookup_shared(name, len, hash);
317 if (found_string != NULL) {
318 return found_string;
319 }
320 if (StringTable::_alt_hash) {
321 hash = hash_string(name, len, true);
322 }
323 return StringTable::the_table()->do_intern(string_or_null_h, name, len,
324 hash, CHECK_NULL);
325 }
326
327 class StringTableCreateEntry : public StackObj {
328 private:
329 Thread* _thread;
330 Handle _return;
331 Handle _store;
332 public:
333 StringTableCreateEntry(Thread* thread, Handle store)
334 : _thread(thread), _store(store) {}
335
336 WeakHandle<vm_string_table_data> operator()() { // No dups found
337 WeakHandle<vm_string_table_data> wh =
338 WeakHandle<vm_string_table_data>::create(_store);
339 return wh;
340 }
341 void operator()(bool inserted, WeakHandle<vm_string_table_data>* val) {
342 oop result = val->resolve();
343 assert(result != NULL, "Result should be reachable");
344 _return = Handle(_thread, result);
345 }
346 oop get_return() const {
347 return _return();
348 }
349 };
350
351 oop StringTable::do_intern(Handle string_or_null_h, jchar* name,
352 int len, uintx hash, TRAPS) {
353 HandleMark hm(THREAD); // cleanup strings created
354 Handle string_h;
355
356 if (!string_or_null_h.is_null()) {
357 string_h = string_or_null_h;
358 } else {
359 string_h = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
360 }
361
362 // Deduplicate the string before it is interned. Note that we should never
363 // deduplicate a string after it has been interned. Doing so will counteract
364 // compiler optimizations done on e.g. interned string literals.
365 Universe::heap()->deduplicate_string(string_h());
366
367 assert(java_lang_String::equals(string_h(), name, len),
368 "string must be properly initialized");
369 assert(len == java_lang_String::length(string_h()), "Must be same length");
370 StringTableLookupOop lookup(THREAD, hash, string_h);
371 StringTableCreateEntry stc(THREAD, string_h);
372
373 bool rehash_warning;
374 _local_table->get_insert_lazy(THREAD, lookup, stc, stc, &rehash_warning);
375 if (rehash_warning) {
376 _needs_rehashing = true;
377 }
378 return stc.get_return();
379 }
380
381 // GC support
382 class StringTableIsAliveCounter : public BoolObjectClosure {
383 BoolObjectClosure* _real_boc;
384 public:
385 size_t _count;
386 size_t _count_total;
387 StringTableIsAliveCounter(BoolObjectClosure* boc) : _real_boc(boc), _count(0),
388 _count_total(0) {}
389 bool do_object_b(oop obj) {
390 bool ret = _real_boc->do_object_b(obj);
391 if (!ret) {
392 ++_count;
393 }
394 ++_count_total;
395 return ret;
396 }
397 };
398
399 void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f,
400 int* processed, int* removed) {
401 DoNothingClosure dnc;
402 assert(is_alive != NULL, "No closure");
403 StringTableIsAliveCounter stiac(is_alive);
404 OopClosure* tmp = f != NULL ? f : &dnc;
405
406 StringTable::the_table()->_weak_handles->weak_oops_do(&stiac, tmp);
407
408 StringTable::the_table()->items_to_clean(stiac._count);
409 StringTable::the_table()->check_concurrent_work();
410 if (processed != NULL) {
411 *processed = (int) stiac._count_total;
412 }
413 if (removed != NULL) {
414 *removed = (int) stiac._count;
415 }
416 }
417
418 void StringTable::oops_do(OopClosure* f) {
419 assert(f != NULL, "No closure");
420 StringTable::the_table()->_weak_handles->oops_do(f);
421 }
422
423 void StringTable::possibly_parallel_unlink(
424 OopStorage::ParState<false, false>* _par_state_string, BoolObjectClosure* cl,
425 int* processed, int* removed)
426 {
427 DoNothingClosure dnc;
428 assert(cl != NULL, "No closure");
429 StringTableIsAliveCounter stiac(cl);
430
431 _par_state_string->weak_oops_do(&stiac, &dnc);
432
433 StringTable::the_table()->items_to_clean(stiac._count);
434 StringTable::the_table()->check_concurrent_work();
435 *processed = (int) stiac._count_total;
436 *removed = (int) stiac._count;
437 }
438
439 void StringTable::possibly_parallel_oops_do(
440 OopStorage::ParState<false /* concurrent */, false /* const */>*
441 _par_state_string, OopClosure* f)
442 {
443 assert(f != NULL, "No closure");
444 _par_state_string->oops_do(f);
445 }
446
447 // Concurrent work
448 void StringTable::grow(JavaThread* jt) {
449 StringTableHash::GrowTask gt(_local_table);
450 if (!gt.prepare(jt)) {
451 return;
452 }
453 log_trace(stringtable)("Started to grow");
454 {
455 TraceTime timer("Grow", TRACETIME_LOG(Debug, stringtable, perf));
456 while (gt.doTask(jt)) {
457 gt.pause(jt);
458 {
459 ThreadBlockInVM tbivm(jt);
460 }
461 gt.cont(jt);
462 }
463 }
464 gt.done(jt);
465 _current_size = table_size(jt);
466 log_debug(stringtable)("Grown to size:" SIZE_FORMAT, _current_size);
467 }
468
469 struct StringTableDoDelete : StackObj {
470 long _count;
471 StringTableDoDelete() : _count(0) {}
472 void operator()(WeakHandle<vm_string_table_data>* val) {
473 ++_count;
474 }
475 };
476
477 struct StringTableDeleteCheck : StackObj {
478 long _count;
479 long _item;
480 StringTableDeleteCheck() : _count(0), _item(0) {}
481 bool operator()(WeakHandle<vm_string_table_data>* val) {
482 ++_item;
483 oop tmp = val->peek();
484 if (tmp == NULL) {
485 ++_count;
486 return true;
487 } else {
488 return false;
489 }
490 }
491 };
492
493 void StringTable::clean_dead_entries(JavaThread* jt) {
494 StringTableHash::BulkDeleteTask bdt(_local_table);
495 if (!bdt.prepare(jt)) {
496 return;
497 }
498
499 StringTableDeleteCheck stdc;
500 StringTableDoDelete stdd;
501 bool interrupted = false;
502 {
503 TraceTime timer("Clean", TRACETIME_LOG(Debug, stringtable, perf));
504 while(bdt.doTask(jt, stdc, stdd)) {
505 bdt.pause(jt);
506 {
507 ThreadBlockInVM tbivm(jt);
508 }
509 if (!bdt.cont(jt)) {
510 interrupted = true;
511 break;
512 }
513 }
514 }
515 if (interrupted) {
516 _has_work = true;
517 } else {
518 bdt.done(jt);
519 }
520 log_debug(stringtable)("Cleaned %ld of %ld", stdc._count, stdc._item);
521 }
522
523 void StringTable::check_concurrent_work() {
524 if (_has_work) {
525 return;
526 }
527 double load_factor = StringTable::get_load_factor();
528 double dead_factor = StringTable::get_dead_factor();
529 // We should clean/resize if we have more dead than alive,
530 // more items than preferred load factor or
531 // more dead items than water mark.
532 if ((dead_factor > load_factor) ||
533 (load_factor > PREF_AVG_LIST_LEN) ||
534 (dead_factor > CLEAN_DEAD_HIGH_WATER_MARK)) {
535 log_debug(stringtable)("Concurrent work triggered, live factor:%g dead factor:%g",
536 load_factor, dead_factor);
537 trigger_concurrent_work();
538 }
539 }
540
541 void StringTable::concurrent_work(JavaThread* jt) {
542 _has_work = false;
543 double load_factor = get_load_factor();
544 log_debug(stringtable, perf)("Concurrent work, live factor: %g", load_factor);
545 // We prefer growing, since that also removes dead items
546 if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
547 grow(jt);
548 } else {
549 clean_dead_entries(jt);
550 }
551 }
552
553 void StringTable::do_concurrent_work(JavaThread* jt) {
554 StringTable::the_table()->concurrent_work(jt);
555 }
556
557 // Rehash
558 bool StringTable::do_rehash() {
559 if (!_local_table->is_safepoint_safe()) {
560 return false;
561 }
562
563 // We use max size
564 StringTableHash* new_table = new StringTableHash(END_SIZE, END_SIZE, REHASH_LEN);
565 // Use alt hash from now on
566 _alt_hash = true;
567 if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) {
568 _alt_hash = false;
569 delete new_table;
570 return false;
571 }
572
573 // free old table
574 delete _local_table;
575 _local_table = new_table;
576
577 return true;
578 }
579
580 void StringTable::try_rehash_table() {
581 static bool rehashed = false;
582 log_debug(stringtable)("Table imbalanced, rehashing called.");
583
584 // Grow instead of rehash.
585 if (get_load_factor() > PREF_AVG_LIST_LEN &&
586 !_local_table->is_max_size_reached()) {
587 log_debug(stringtable)("Choosing growing over rehashing.");
588 trigger_concurrent_work();
589 _needs_rehashing = false;
590 return;
591 }
592 // Already rehashed.
593 if (rehashed) {
594 log_warning(stringtable)("Rehashing already done, still long lists.");
595 trigger_concurrent_work();
596 _needs_rehashing = false;
597 return;
598 }
599
600 murmur_seed = AltHashing::compute_seed();
601 {
602 if (do_rehash()) {
603 rehashed = true;
604 } else {
605 log_info(stringtable)("Resizes in progress rehashing skipped.");
606 }
607 }
608 _needs_rehashing = false;
609 }
610
611 void StringTable::rehash_table() {
612 StringTable::the_table()->try_rehash_table();
613 }
614
615 // Statistics
616 static int literal_size(oop obj) {
617 // NOTE: this would over-count if (pre-JDK8)
618 // java_lang_Class::has_offset_field() is true and the String.value array is
619 // shared by several Strings. However, starting from JDK8, the String.value
620 // array is not shared anymore.
621 if (obj == NULL) {
622 return 0;
623 } else if (obj->klass() == SystemDictionary::String_klass()) {
624 return (obj->size() + java_lang_String::value(obj)->size()) * HeapWordSize;
625 } else {
626 return obj->size();
627 }
628 }
629
630 struct SizeFunc : StackObj {
631 size_t operator()(WeakHandle<vm_string_table_data>* val) {
632 oop s = val->peek();
633 if (s == NULL) {
634 // Dead
635 return 0;
636 }
637 return literal_size(s);
638 };
639 };
640
641 void StringTable::print_table_statistics(outputStream* st,
642 const char* table_name) {
643 SizeFunc sz;
644 _local_table->statistics_to(Thread::current(), sz, st, table_name);
645 }
646
647 // Verification
648 class VerifyStrings : StackObj {
649 public:
650 bool operator()(WeakHandle<vm_string_table_data>* val) {
651 oop s = val->peek();
652 if (s != NULL) {
653 assert(java_lang_String::length(s) >= 0, "Length on string must work.");
654 }
655 return true;
656 };
657 };
658
659 // This verification is part of Universe::verify() and needs to be quick.
660 void StringTable::verify() {
661 Thread* thr = Thread::current();
662 VerifyStrings vs;
663 if (!the_table()->_local_table->try_scan(thr, vs)) {
664 log_info(stringtable)("verify unavailable at this moment");
665 }
666 }
667
668 // Verification and comp
669 class VerifyCompStrings : StackObj {
670 GrowableArray<oop>* _oops;
671 public:
672 size_t _errors;
673 VerifyCompStrings(GrowableArray<oop>* oops) : _oops(oops), _errors(0) {}
674 bool operator()(WeakHandle<vm_string_table_data>* val) {
675 oop s = val->resolve();
676 if (s == NULL) {
677 return true;
678 }
679 int len = _oops->length();
680 for (int i = 0; i < len; i++) {
681 bool eq = java_lang_String::equals(s, _oops->at(i));
682 assert(!eq, "Duplicate strings");
683 if (eq) {
684 _errors++;
685 }
686 }
687 _oops->push(s);
688 return true;
689 };
690 };
691
692 size_t StringTable::verify_and_compare_entries() {
693 Thread* thr = Thread::current();
694 GrowableArray<oop>* oops =
695 new (ResourceObj::C_HEAP, mtInternal)
696 GrowableArray<oop>((int)the_table()->_current_size, true);
697
698 VerifyCompStrings vcs(oops);
699 if (!the_table()->_local_table->try_scan(thr, vcs)) {
700 log_info(stringtable)("verify unavailable at this moment");
701 }
702 delete oops;
703 return vcs._errors;
704 }
705
706 // Dumping
707 class PrintString : StackObj {
708 Thread* _thr;
709 outputStream* _st;
710 public:
711 PrintString(Thread* thr, outputStream* st) : _thr(thr), _st(st) {}
712 bool operator()(WeakHandle<vm_string_table_data>* val) {
713 oop s = val->peek();
714 if (s == NULL) {
715 return true;
716 }
717 typeArrayOop value = java_lang_String::value_no_keepalive(s);
718 int length = java_lang_String::length(s);
719 bool is_latin1 = java_lang_String::is_latin1(s);
720
721 if (length <= 0) {
722 _st->print("%d: ", length);
723 } else {
724 ResourceMark rm(_thr);
725 int utf8_length = length;
726 char* utf8_string;
727
728 if (!is_latin1) {
729 jchar* chars = value->char_at_addr(0);
730 utf8_string = UNICODE::as_utf8(chars, utf8_length);
731 } else {
732 jbyte* bytes = value->byte_at_addr(0);
733 utf8_string = UNICODE::as_utf8(bytes, utf8_length);
734 }
735
736 _st->print("%d: ", utf8_length);
737 HashtableTextDump::put_utf8(_st, utf8_string, utf8_length);
738 }
739 _st->cr();
740 return true;
741 };
742 };
743
744 void StringTable::dump(outputStream* st, bool verbose) {
745 if (!verbose) {
746 the_table()->print_table_statistics(st, "StringTable");
747 } else {
748 Thread* thr = Thread::current();
749 ResourceMark rm(thr);
750 st->print_cr("VERSION: 1.1");
751 PrintString ps(thr, st);
752 if (!the_table()->_local_table->try_scan(thr, ps)) {
753 st->print_cr("dump unavailable at this moment");
754 }
755 }
756 }
757
758 // Utility for dumping strings
759 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
760 DCmdWithParser(output, heap),
761 _verbose("-verbose", "Dump the content of each string in the table",
762 "BOOLEAN", false, "false") {
763 _dcmdparser.add_dcmd_option(&_verbose);
764 }
765
766 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
767 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
768 _verbose.value());
769 VMThread::execute(&dumper);
770 }
771
772 int StringtableDCmd::num_arguments() {
773 ResourceMark rm;
774 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
775 if (dcmd != NULL) {
776 DCmdMark mark(dcmd);
777 return dcmd->_dcmdparser.num_arguments();
778 } else {
779 return 0;
780 }
781 }
782
783 // Sharing
784 #if INCLUDE_CDS_JAVA_HEAP
785 oop StringTable::lookup_shared(jchar* name, int len, unsigned int hash) {
786 assert(hash == java_lang_String::hash_code(name, len),
787 "hash must be computed using java_lang_String::hash_code");
788 return _shared_table.lookup((const char*)name, hash, len);
789 }
790
791 oop StringTable::create_archived_string(oop s, Thread* THREAD) {
792 assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
793
794 oop new_s = NULL;
795 typeArrayOop v = java_lang_String::value_no_keepalive(s);
796 typeArrayOop new_v =
797 (typeArrayOop)MetaspaceShared::archive_heap_object(v, THREAD);
798 if (new_v == NULL) {
799 return NULL;
800 }
801 new_s = MetaspaceShared::archive_heap_object(s, THREAD);
802 if (new_s == NULL) {
803 return NULL;
804 }
805
806 // adjust the pointer to the 'value' field in the new String oop
807 java_lang_String::set_value_raw(new_s, new_v);
808 return new_s;
809 }
810
811 struct CopyToArchive : StackObj {
812 CompactStringTableWriter* _writer;
813 CopyToArchive(CompactStringTableWriter* writer) : _writer(writer) {}
814 bool operator()(WeakHandle<vm_string_table_data>* val) {
815 oop s = val->peek();
816 if (s == NULL) {
817 return true;
818 }
819 unsigned int hash = java_lang_String::hash_code(s);
820 if (hash == 0) {
821 return true;
822 }
823
824 java_lang_String::set_hash(s, hash);
825 oop new_s = StringTable::create_archived_string(s, Thread::current());
826 if (new_s == NULL) {
827 return true;
828 }
829
830 val->replace(new_s);
831 // add to the compact table
832 _writer->add(hash, new_s);
833 return true;
834 }
835 };
836
837 void StringTable::copy_shared_string_table(CompactStringTableWriter* writer) {
838 assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
839
840 CopyToArchive copy(writer);
841 StringTable::the_table()->_local_table->do_scan(Thread::current(), copy);
842 }
843
844 void StringTable::write_to_archive() {
845 assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
846
847 _shared_table.reset();
848 int num_buckets = the_table()->_items / SharedSymbolTableBucketSize;
849 // calculation of num_buckets can result in zero buckets, we need at least one
850 CompactStringTableWriter writer(num_buckets > 1 ? num_buckets : 1,
851 &MetaspaceShared::stats()->string);
852
853 // Copy the interned strings into the "string space" within the java heap
854 copy_shared_string_table(&writer);
855 writer.dump(&_shared_table);
856 }
857
858 void StringTable::serialize(SerializeClosure* soc) {
859 _shared_table.set_type(CompactHashtable<oop, char>::_string_table);
860 _shared_table.serialize(soc);
861
862 if (soc->writing()) {
863 // Sanity. Make sure we don't use the shared table at dump time
864 _shared_table.reset();
865 } else if (!_shared_string_mapped) {
866 _shared_table.reset();
867 }
868 }
869
870 void StringTable::shared_oops_do(OopClosure* f) {
871 _shared_table.oops_do(f);
872 }
873 #endif //INCLUDE_CDS_JAVA_HEAP