1 /*
2 * Copyright (c) 1997, 2016, 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.inline.hpp"
32 #include "gc/shared/gcLocker.inline.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/filemap.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "runtime/atomic.inline.hpp"
37 #include "runtime/mutexLocker.hpp"
38 #include "utilities/hashtable.inline.hpp"
39 #include "utilities/macros.hpp"
40 #if INCLUDE_ALL_GCS
41 #include "gc/g1/g1CollectedHeap.hpp"
42 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
43 #include "gc/g1/g1StringDedup.hpp"
44 #endif
45
46 // the number of buckets a thread claims
47 const int ClaimChunkSize = 32;
48
49 #ifdef ASSERT
50 class StableMemoryChecker : public StackObj {
51 enum { _bufsize = wordSize*4 };
52
53 address _region;
54 jint _size;
55 u1 _save_buf[_bufsize];
56
57 int sample(u1* save_buf) {
58 if (_size <= _bufsize) {
59 memcpy(save_buf, _region, _size);
60 return _size;
61 } else {
62 // copy head and tail
63 memcpy(&save_buf[0], _region, _bufsize/2);
64 memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
65 return (_bufsize/2)*2;
66 }
67 }
68
69 public:
70 StableMemoryChecker(const void* region, jint size) {
71 _region = (address) region;
72 _size = size;
73 sample(_save_buf);
74 }
75
76 bool verify() {
77 u1 check_buf[sizeof(_save_buf)];
78 int check_size = sample(check_buf);
79 return (0 == memcmp(_save_buf, check_buf, check_size));
80 }
81
82 void set_region(const void* region) { _region = (address) region; }
83 };
84 #endif
85
86
87 // --------------------------------------------------------------------------
88 StringTable* StringTable::_the_table = NULL;
89 bool StringTable::_ignore_shared_strings = false;
90 bool StringTable::_needs_rehashing = false;
91
92 volatile int StringTable::_parallel_claimed_idx = 0;
93
94 CompactHashtable<oop, char> StringTable::_shared_table;
95
96 // Pick hashing algorithm
97 template<typename T>
98 unsigned int StringTable::hash_string(const T* s, int len) {
99 return use_alternate_hashcode() ? AltHashing::murmur3_32(seed(), s, len) :
100 java_lang_String::hash_code(s, len);
101 }
102
103 // Explicit instantiation for all supported types.
104 template unsigned int StringTable::hash_string<jchar>(const jchar* s, int len);
105 template unsigned int StringTable::hash_string<jbyte>(const jbyte* s, int len);
106
107 oop StringTable::lookup_shared(jchar* name, int len) {
108 // java_lang_String::hash_code() was used to compute hash values in the shared table. Don't
109 // use the hash value from StringTable::hash_string() as it might use alternate hashcode.
110 return _shared_table.lookup((const char*)name,
111 java_lang_String::hash_code(name, len), len);
112 }
113
114 // Tell the GC that this string was looked up in the StringTable.
115 static void ensure_string_alive(oop string) {
116 // A lookup in the StringTable could return an object that was previously
117 // considered dead. The SATB part of G1 needs to get notified about this
118 // potential resurrection, otherwise the marking might not find the object.
119 #if INCLUDE_ALL_GCS
120 assert(string != NULL, "should only be called when string found in table");
121 if (UseG1GC) {
122 G1SATBCardTableModRefBS::enqueue(string);
123 }
124 #endif
125 }
126
127 oop StringTable::lookup_in_main_table(int index, jchar* name,
128 int len, unsigned int hash) {
129 int count = 0;
130 for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) {
131 count++;
132 if (l->hash() == hash) {
133 if (java_lang_String::equals(l->literal(), name, len)) {
134 oop result = l->literal();
135 ensure_string_alive(result);
136 return result;
137 }
138 }
139 }
140 // If the bucket size is too deep check if this hash code is insufficient.
141 if (count >= rehash_count && !needs_rehashing()) {
142 _needs_rehashing = check_rehash_table(count);
143 }
144 return NULL;
145 }
146
147
148 oop StringTable::basic_add(int index_arg, Handle string, jchar* name,
149 int len, unsigned int hashValue_arg, TRAPS) {
150
151 assert(java_lang_String::equals(string(), name, len),
152 "string must be properly initialized");
153 // Cannot hit a safepoint in this function because the "this" pointer can move.
154 NoSafepointVerifier nsv;
155
156 // Check if the symbol table has been rehashed, if so, need to recalculate
157 // the hash value and index before second lookup.
158 unsigned int hashValue;
159 int index;
160 if (use_alternate_hashcode()) {
161 hashValue = hash_string(name, len);
162 index = hash_to_index(hashValue);
163 } else {
164 hashValue = hashValue_arg;
165 index = index_arg;
166 }
167
168 // Since look-up was done lock-free, we need to check if another
169 // thread beat us in the race to insert the symbol.
170
171 // No need to lookup the shared table from here since the caller (intern()) already did
172 oop test = lookup_in_main_table(index, name, len, hashValue); // calls lookup(u1*, int)
173 if (test != NULL) {
174 // Entry already added
175 return test;
176 }
177
178 HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string());
179 add_entry(index, entry);
180 return string();
181 }
182
183
184 oop StringTable::lookup(Symbol* symbol) {
185 ResourceMark rm;
186 int length;
187 jchar* chars = symbol->as_unicode(length);
188 return lookup(chars, length);
189 }
190
191 oop StringTable::lookup(jchar* name, int len) {
192 oop string = lookup_shared(name, len);
193 if (string != NULL) {
194 return string;
195 }
196
197 unsigned int hash = hash_string(name, len);
198 int index = the_table()->hash_to_index(hash);
199 string = the_table()->lookup_in_main_table(index, name, len, hash);
200 return string;
201 }
202
203
204 oop StringTable::intern(Handle string_or_null, jchar* name,
205 int len, TRAPS) {
206 oop found_string = lookup_shared(name, len);
207 if (found_string != NULL) {
208 return found_string;
209 }
210
211 unsigned int hashValue = hash_string(name, len);
212 int index = the_table()->hash_to_index(hashValue);
213 found_string = the_table()->lookup_in_main_table(index, name, len, hashValue);
214
215 // Found
216 if (found_string != NULL) {
217 return found_string;
218 }
219
220 debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
221 assert(!Universe::heap()->is_in_reserved(name),
222 "proposed name of symbol must be stable");
223
224 Handle string;
225 // try to reuse the string if possible
226 if (!string_or_null.is_null()) {
227 string = string_or_null;
228 } else {
229 string = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
230 }
231
232 #if INCLUDE_ALL_GCS
233 if (G1StringDedup::is_enabled()) {
234 // Deduplicate the string before it is interned. Note that we should never
235 // deduplicate a string after it has been interned. Doing so will counteract
236 // compiler optimizations done on e.g. interned string literals.
237 G1StringDedup::deduplicate(string());
238 }
239 #endif
240
241 // Grab the StringTable_lock before getting the_table() because it could
242 // change at safepoint.
243 oop added_or_found;
244 {
245 MutexLocker ml(StringTable_lock, THREAD);
246 // Otherwise, add to symbol to table
247 added_or_found = the_table()->basic_add(index, string, name, len,
248 hashValue, CHECK_NULL);
249 }
250
251 return added_or_found;
252 }
253
254 oop StringTable::intern(Symbol* symbol, TRAPS) {
255 if (symbol == NULL) return NULL;
256 ResourceMark rm(THREAD);
257 int length;
258 jchar* chars = symbol->as_unicode(length);
259 Handle string;
260 oop result = intern(string, chars, length, CHECK_NULL);
261 return result;
262 }
263
264
265 oop StringTable::intern(oop string, TRAPS)
266 {
267 if (string == NULL) return NULL;
268 ResourceMark rm(THREAD);
269 int length;
270 Handle h_string (THREAD, string);
271 jchar* chars = java_lang_String::as_unicode_string(string, length, CHECK_NULL);
272 oop result = intern(h_string, chars, length, CHECK_NULL);
273 return result;
274 }
275
276
277 oop StringTable::intern(const char* utf8_string, TRAPS) {
278 if (utf8_string == NULL) return NULL;
279 ResourceMark rm(THREAD);
280 int length = UTF8::unicode_length(utf8_string);
281 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
282 UTF8::convert_to_unicode(utf8_string, chars, length);
283 Handle string;
284 oop result = intern(string, chars, length, CHECK_NULL);
285 return result;
286 }
287
288 void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
289 buckets_unlink_or_oops_do(is_alive, f, 0, the_table()->table_size(), processed, removed);
290 }
291
292 void StringTable::possibly_parallel_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
293 // Readers of the table are unlocked, so we should only be removing
294 // entries at a safepoint.
295 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
296 const int limit = the_table()->table_size();
297
298 for (;;) {
299 // Grab next set of buckets to scan
300 int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
301 if (start_idx >= limit) {
302 // End of table
303 break;
304 }
305
306 int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
307 buckets_unlink_or_oops_do(is_alive, f, start_idx, end_idx, processed, removed);
308 }
309 }
310
311 void StringTable::buckets_oops_do(OopClosure* f, int start_idx, int end_idx) {
312 const int limit = the_table()->table_size();
313
314 assert(0 <= start_idx && start_idx <= limit,
315 "start_idx (%d) is out of bounds", start_idx);
316 assert(0 <= end_idx && end_idx <= limit,
317 "end_idx (%d) is out of bounds", end_idx);
318 assert(start_idx <= end_idx,
319 "Index ordering: start_idx=%d, end_idx=%d",
320 start_idx, end_idx);
321
322 for (int i = start_idx; i < end_idx; i += 1) {
323 HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
324 while (entry != NULL) {
325 assert(!entry->is_shared(), "CDS not used for the StringTable");
326
327 f->do_oop((oop*)entry->literal_addr());
328
329 entry = entry->next();
330 }
331 }
332 }
333
334 void StringTable::buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, int* processed, int* removed) {
335 const int limit = the_table()->table_size();
336
337 assert(0 <= start_idx && start_idx <= limit,
338 "start_idx (%d) is out of bounds", start_idx);
339 assert(0 <= end_idx && end_idx <= limit,
340 "end_idx (%d) is out of bounds", end_idx);
341 assert(start_idx <= end_idx,
342 "Index ordering: start_idx=%d, end_idx=%d",
343 start_idx, end_idx);
344
345 for (int i = start_idx; i < end_idx; ++i) {
346 HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i);
347 HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
348 while (entry != NULL) {
349 assert(!entry->is_shared(), "CDS not used for the StringTable");
350
351 if (is_alive->do_object_b(entry->literal())) {
352 if (f != NULL) {
353 f->do_oop((oop*)entry->literal_addr());
354 }
355 p = entry->next_addr();
356 } else {
357 *p = entry->next();
358 the_table()->free_entry(entry);
359 (*removed)++;
360 }
361 (*processed)++;
362 entry = *p;
363 }
364 }
365 }
366
367 void StringTable::oops_do(OopClosure* f) {
368 buckets_oops_do(f, 0, the_table()->table_size());
369 }
370
371 void StringTable::possibly_parallel_oops_do(OopClosure* f) {
372 const int limit = the_table()->table_size();
373
374 for (;;) {
375 // Grab next set of buckets to scan
376 int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
377 if (start_idx >= limit) {
378 // End of table
379 break;
380 }
381
382 int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
383 buckets_oops_do(f, start_idx, end_idx);
384 }
385 }
386
387 // This verification is part of Universe::verify() and needs to be quick.
388 // See StringTable::verify_and_compare() below for exhaustive verification.
389 void StringTable::verify() {
390 for (int i = 0; i < the_table()->table_size(); ++i) {
391 HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
392 for ( ; p != NULL; p = p->next()) {
393 oop s = p->literal();
394 guarantee(s != NULL, "interned string is NULL");
395 unsigned int h = java_lang_String::hash_string(s);
396 guarantee(p->hash() == h, "broken hash in string table entry");
397 guarantee(the_table()->hash_to_index(h) == i,
398 "wrong index in string table");
399 }
400 }
401 }
402
403 void StringTable::dump(outputStream* st, bool verbose) {
404 if (!verbose) {
405 the_table()->dump_table(st, "StringTable");
406 } else {
407 Thread* THREAD = Thread::current();
408 st->print_cr("VERSION: 1.1");
409 for (int i = 0; i < the_table()->table_size(); ++i) {
410 HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
411 for ( ; p != NULL; p = p->next()) {
412 oop s = p->literal();
413 typeArrayOop value = java_lang_String::value(s);
414 int length = java_lang_String::length(s);
415 bool is_latin1 = java_lang_String::is_latin1(s);
416
417 if (length <= 0) {
418 st->print("%d: ", length);
419 } else {
420 ResourceMark rm(THREAD);
421 int utf8_length;
422 char* utf8_string;
423
424 if (!is_latin1) {
425 jchar* chars = value->char_at_addr(0);
426 utf8_length = UNICODE::utf8_length(chars, length);
427 utf8_string = UNICODE::as_utf8(chars, length);
428 } else {
429 jbyte* bytes = value->byte_at_addr(0);
430 utf8_length = UNICODE::utf8_length(bytes, length);
431 utf8_string = UNICODE::as_utf8(bytes, length);
432 }
433
434 st->print("%d: ", utf8_length);
435 HashtableTextDump::put_utf8(st, utf8_string, utf8_length);
436 }
437 st->cr();
438 }
439 }
440 }
441 }
442
443 StringTable::VerifyRetTypes StringTable::compare_entries(
444 int bkt1, int e_cnt1,
445 HashtableEntry<oop, mtSymbol>* e_ptr1,
446 int bkt2, int e_cnt2,
447 HashtableEntry<oop, mtSymbol>* e_ptr2) {
448 // These entries are sanity checked by verify_and_compare_entries()
449 // before this function is called.
450 oop str1 = e_ptr1->literal();
451 oop str2 = e_ptr2->literal();
452
453 if (str1 == str2) {
454 tty->print_cr("ERROR: identical oop values (0x" PTR_FORMAT ") "
455 "in entry @ bucket[%d][%d] and entry @ bucket[%d][%d]",
456 p2i(str1), bkt1, e_cnt1, bkt2, e_cnt2);
457 return _verify_fail_continue;
458 }
459
460 if (java_lang_String::equals(str1, str2)) {
461 tty->print_cr("ERROR: identical String values in entry @ "
462 "bucket[%d][%d] and entry @ bucket[%d][%d]",
463 bkt1, e_cnt1, bkt2, e_cnt2);
464 return _verify_fail_continue;
465 }
466
467 return _verify_pass;
468 }
469
470 StringTable::VerifyRetTypes StringTable::verify_entry(int bkt, int e_cnt,
471 HashtableEntry<oop, mtSymbol>* e_ptr,
472 StringTable::VerifyMesgModes mesg_mode) {
473
474 VerifyRetTypes ret = _verify_pass; // be optimistic
475
476 oop str = e_ptr->literal();
477 if (str == NULL) {
478 if (mesg_mode == _verify_with_mesgs) {
479 tty->print_cr("ERROR: NULL oop value in entry @ bucket[%d][%d]", bkt,
480 e_cnt);
481 }
482 // NULL oop means no more verifications are possible
483 return _verify_fail_done;
484 }
485
486 if (str->klass() != SystemDictionary::String_klass()) {
487 if (mesg_mode == _verify_with_mesgs) {
488 tty->print_cr("ERROR: oop is not a String in entry @ bucket[%d][%d]",
489 bkt, e_cnt);
490 }
491 // not a String means no more verifications are possible
492 return _verify_fail_done;
493 }
494
495 unsigned int h = java_lang_String::hash_string(str);
496 if (e_ptr->hash() != h) {
497 if (mesg_mode == _verify_with_mesgs) {
498 tty->print_cr("ERROR: broken hash value in entry @ bucket[%d][%d], "
499 "bkt_hash=%d, str_hash=%d", bkt, e_cnt, e_ptr->hash(), h);
500 }
501 ret = _verify_fail_continue;
502 }
503
504 if (the_table()->hash_to_index(h) != bkt) {
505 if (mesg_mode == _verify_with_mesgs) {
506 tty->print_cr("ERROR: wrong index value for entry @ bucket[%d][%d], "
507 "str_hash=%d, hash_to_index=%d", bkt, e_cnt, h,
508 the_table()->hash_to_index(h));
509 }
510 ret = _verify_fail_continue;
511 }
512
513 return ret;
514 }
515
516 // See StringTable::verify() above for the quick verification that is
517 // part of Universe::verify(). This verification is exhaustive and
518 // reports on every issue that is found. StringTable::verify() only
519 // reports on the first issue that is found.
520 //
521 // StringTable::verify_entry() checks:
522 // - oop value != NULL (same as verify())
523 // - oop value is a String
524 // - hash(String) == hash in entry (same as verify())
525 // - index for hash == index of entry (same as verify())
526 //
527 // StringTable::compare_entries() checks:
528 // - oops are unique across all entries
529 // - String values are unique across all entries
530 //
531 int StringTable::verify_and_compare_entries() {
532 assert(StringTable_lock->is_locked(), "sanity check");
533
534 int fail_cnt = 0;
535
536 // first, verify all the entries individually:
537 for (int bkt = 0; bkt < the_table()->table_size(); bkt++) {
538 HashtableEntry<oop, mtSymbol>* e_ptr = the_table()->bucket(bkt);
539 for (int e_cnt = 0; e_ptr != NULL; e_ptr = e_ptr->next(), e_cnt++) {
540 VerifyRetTypes ret = verify_entry(bkt, e_cnt, e_ptr, _verify_with_mesgs);
541 if (ret != _verify_pass) {
542 fail_cnt++;
543 }
544 }
545 }
546
547 // Optimization: if the above check did not find any failures, then
548 // the comparison loop below does not need to call verify_entry()
549 // before calling compare_entries(). If there were failures, then we
550 // have to call verify_entry() to see if the entry can be passed to
551 // compare_entries() safely. When we call verify_entry() in the loop
552 // below, we do so quietly to void duplicate messages and we don't
553 // increment fail_cnt because the failures have already been counted.
554 bool need_entry_verify = (fail_cnt != 0);
555
556 // second, verify all entries relative to each other:
557 for (int bkt1 = 0; bkt1 < the_table()->table_size(); bkt1++) {
558 HashtableEntry<oop, mtSymbol>* e_ptr1 = the_table()->bucket(bkt1);
559 for (int e_cnt1 = 0; e_ptr1 != NULL; e_ptr1 = e_ptr1->next(), e_cnt1++) {
560 if (need_entry_verify) {
561 VerifyRetTypes ret = verify_entry(bkt1, e_cnt1, e_ptr1,
562 _verify_quietly);
563 if (ret == _verify_fail_done) {
564 // cannot use the current entry to compare against other entries
565 continue;
566 }
567 }
568
569 for (int bkt2 = bkt1; bkt2 < the_table()->table_size(); bkt2++) {
570 HashtableEntry<oop, mtSymbol>* e_ptr2 = the_table()->bucket(bkt2);
571 int e_cnt2;
572 for (e_cnt2 = 0; e_ptr2 != NULL; e_ptr2 = e_ptr2->next(), e_cnt2++) {
573 if (bkt1 == bkt2 && e_cnt2 <= e_cnt1) {
574 // skip the entries up to and including the one that
575 // we're comparing against
576 continue;
577 }
578
579 if (need_entry_verify) {
580 VerifyRetTypes ret = verify_entry(bkt2, e_cnt2, e_ptr2,
581 _verify_quietly);
582 if (ret == _verify_fail_done) {
583 // cannot compare against this entry
584 continue;
585 }
586 }
587
588 // compare two entries, report and count any failures:
589 if (compare_entries(bkt1, e_cnt1, e_ptr1, bkt2, e_cnt2, e_ptr2)
590 != _verify_pass) {
591 fail_cnt++;
592 }
593 }
594 }
595 }
596 }
597 return fail_cnt;
598 }
599
600 // Create a new table and using alternate hash code, populate the new table
601 // with the existing strings. Set flag to use the alternate hash code afterwards.
602 void StringTable::rehash_table() {
603 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
604 // This should never happen with -Xshare:dump but it might in testing mode.
605 if (DumpSharedSpaces) return;
606 StringTable* new_table = new StringTable();
607
608 // Rehash the table
609 the_table()->move_to(new_table);
610
611 // Delete the table and buckets (entries are reused in new table).
612 delete _the_table;
613 // Don't check if we need rehashing until the table gets unbalanced again.
614 // Then rehash with a new global seed.
615 _needs_rehashing = false;
616 _the_table = new_table;
617 }
618
619 // Utility for dumping strings
620 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
621 DCmdWithParser(output, heap),
622 _verbose("-verbose", "Dump the content of each string in the table",
623 "BOOLEAN", false, "false") {
624 _dcmdparser.add_dcmd_option(&_verbose);
625 }
626
627 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
628 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
629 _verbose.value());
630 VMThread::execute(&dumper);
631 }
632
633 int StringtableDCmd::num_arguments() {
634 ResourceMark rm;
635 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
636 if (dcmd != NULL) {
637 DCmdMark mark(dcmd);
638 return dcmd->_dcmdparser.num_arguments();
639 } else {
640 return 0;
641 }
642 }
643
644 // Sharing
645 bool StringTable::copy_shared_string(GrowableArray<MemRegion> *string_space,
646 CompactHashtableWriter* ch_table) {
647 #if INCLUDE_CDS && INCLUDE_ALL_GCS && defined(_LP64) && !defined(_WINDOWS)
648 assert(UseG1GC, "Only support G1 GC");
649 assert(UseCompressedOops && UseCompressedClassPointers,
650 "Only support UseCompressedOops and UseCompressedClassPointers enabled");
651
652 Thread* THREAD = Thread::current();
653 G1CollectedHeap::heap()->begin_archive_alloc_range();
654 for (int i = 0; i < the_table()->table_size(); ++i) {
655 HashtableEntry<oop, mtSymbol>* bucket = the_table()->bucket(i);
656 for ( ; bucket != NULL; bucket = bucket->next()) {
657 oop s = bucket->literal();
658 unsigned int hash = java_lang_String::hash_code(s);
659 if (hash == 0) {
660 continue;
661 }
662
663 // allocate the new 'value' array first
664 typeArrayOop v = java_lang_String::value(s);
665 int v_len = v->size();
666 typeArrayOop new_v;
667 if (G1CollectedHeap::heap()->is_archive_alloc_too_large(v_len)) {
668 continue; // skip the current String. The 'value' array is too large to handle
669 } else {
670 new_v = (typeArrayOop)G1CollectedHeap::heap()->archive_mem_allocate(v_len);
671 if (new_v == NULL) {
672 return false; // allocation failed
673 }
674 }
675 // now allocate the new String object
676 int s_len = s->size();
677 oop new_s = (oop)G1CollectedHeap::heap()->archive_mem_allocate(s_len);
678 if (new_s == NULL) {
679 return false;
680 }
681
682 s->identity_hash();
683 v->identity_hash();
684
685 // copy the objects' data
686 Copy::aligned_disjoint_words((HeapWord*)s, (HeapWord*)new_s, s_len);
687 Copy::aligned_disjoint_words((HeapWord*)v, (HeapWord*)new_v, v_len);
688
689 // adjust the pointer to the 'value' field in the new String oop. Also pre-compute and set the
690 // 'hash' field. That avoids "write" to the shared strings at runtime by the deduplication process.
691 java_lang_String::set_value_raw(new_s, new_v);
692 if (java_lang_String::hash(new_s) == 0) {
693 java_lang_String::set_hash(new_s, hash);
694 }
695
696 // add to the compact table
697 ch_table->add(hash, new_s);
698 }
699 }
700
701 G1CollectedHeap::heap()->end_archive_alloc_range(string_space, os::vm_allocation_granularity());
702 assert(string_space->length() <= 2, "sanity");
703 #endif
704 return true;
705 }
706
707 bool StringTable::copy_compact_table(char** top, char *end, GrowableArray<MemRegion> *string_space,
708 size_t* space_size) {
709 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
710 if (!(UseG1GC && UseCompressedOops && UseCompressedClassPointers)) {
711 if (PrintSharedSpaces) {
712 tty->print_cr("Shared strings are excluded from the archive as UseG1GC, "
713 "UseCompressedOops and UseCompressedClassPointers are required.");
714 }
715 return true;
716 }
717
718 CompactHashtableWriter ch_table(CompactHashtable<oop, char>::_string_table,
719 the_table()->number_of_entries(),
720 &MetaspaceShared::stats()->string);
721
722 // Copy the interned strings into the "string space" within the java heap
723 if (!copy_shared_string(string_space, &ch_table)) {
724 return false;
725 }
726
727 for (int i = 0; i < string_space->length(); i++) {
728 *space_size += string_space->at(i).byte_size();
729 }
730
731 // Now dump the compact table
732 if (*top + ch_table.get_required_bytes() > end) {
733 // not enough space left
734 return false;
735 }
736 ch_table.dump(top, end);
737 *top = (char*)align_ptr_up(*top, sizeof(void*));
738
739 #endif
740 return true;
741 }
742
743 void StringTable::shared_oops_do(OopClosure* f) {
744 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
745 _shared_table.oops_do(f);
746 #endif
747 }
748
749 const char* StringTable::init_shared_table(FileMapInfo *mapinfo, char *buffer) {
750 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
751 if (mapinfo->space_capacity(MetaspaceShared::first_string) == 0) {
752 // no shared string data
753 return buffer;
754 }
755
756 // initialize the shared table
757 juint *p = (juint*)buffer;
758 const char* end = _shared_table.init(
759 CompactHashtable<oop, char>::_string_table, (char*)p);
760 const char* aligned_end = (const char*)align_ptr_up(end, sizeof(void*));
761
762 if (_ignore_shared_strings) {
763 _shared_table.reset();
764 }
765
766 return aligned_end;
767 #endif
768
769 return buffer;
770 }