1 /*
2 * Copyright (c) 1997, 2015, 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.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 oop StringTable::lookup_in_main_table(int index, jchar* name,
115 int len, unsigned int hash) {
116 int count = 0;
117 for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) {
118 count++;
119 if (l->hash() == hash) {
120 if (java_lang_String::equals(l->literal(), name, len)) {
121 return l->literal();
122 }
123 }
124 }
125 // If the bucket size is too deep check if this hash code is insufficient.
126 if (count >= rehash_count && !needs_rehashing()) {
127 _needs_rehashing = check_rehash_table(count);
128 }
129 return NULL;
130 }
131
132
133 oop StringTable::basic_add(int index_arg, Handle string, jchar* name,
134 int len, unsigned int hashValue_arg, TRAPS) {
135
136 assert(java_lang_String::equals(string(), name, len),
137 "string must be properly initialized");
138 // Cannot hit a safepoint in this function because the "this" pointer can move.
139 No_Safepoint_Verifier nsv;
140
141 // Check if the symbol table has been rehashed, if so, need to recalculate
142 // the hash value and index before second lookup.
143 unsigned int hashValue;
144 int index;
145 if (use_alternate_hashcode()) {
146 hashValue = hash_string(name, len);
147 index = hash_to_index(hashValue);
148 } else {
149 hashValue = hashValue_arg;
150 index = index_arg;
151 }
152
153 // Since look-up was done lock-free, we need to check if another
154 // thread beat us in the race to insert the symbol.
155
156 // No need to lookup the shared table from here since the caller (intern()) already did
157 oop test = lookup_in_main_table(index, name, len, hashValue); // calls lookup(u1*, int)
158 if (test != NULL) {
159 // Entry already added
160 return test;
161 }
162
163 HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string());
164 add_entry(index, entry);
165 return string();
166 }
167
168
169 oop StringTable::lookup(Symbol* symbol) {
170 ResourceMark rm;
171 int length;
172 jchar* chars = symbol->as_unicode(length);
173 return lookup(chars, length);
174 }
175
176 // Tell the GC that this string was looked up in the StringTable.
177 static void ensure_string_alive(oop string) {
178 // A lookup in the StringTable could return an object that was previously
179 // considered dead. The SATB part of G1 needs to get notified about this
180 // potential resurrection, otherwise the marking might not find the object.
181 #if INCLUDE_ALL_GCS
182 if (UseG1GC && string != NULL) {
183 G1SATBCardTableModRefBS::enqueue(string);
184 }
185 #endif
186 }
187
188 oop StringTable::lookup(jchar* name, int len) {
189 oop string = lookup_shared(name, len);
190 if (string != NULL) {
191 return string;
192 }
193
194 unsigned int hash = hash_string(name, len);
195 int index = the_table()->hash_to_index(hash);
196 string = the_table()->lookup_in_main_table(index, name, len, hash);
197
198 ensure_string_alive(string);
199
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 ensure_string_alive(found_string);
218 return found_string;
219 }
220
221 debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
222 assert(!Universe::heap()->is_in_reserved(name),
223 "proposed name of symbol must be stable");
224
225 Handle string;
226 // try to reuse the string if possible
227 if (!string_or_null.is_null()) {
228 string = string_or_null;
229 } else {
230 string = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
231 }
232
233 #if INCLUDE_ALL_GCS
234 if (G1StringDedup::is_enabled()) {
235 // Deduplicate the string before it is interned. Note that we should never
236 // deduplicate a string after it has been interned. Doing so will counteract
237 // compiler optimizations done on e.g. interned string literals.
238 G1StringDedup::deduplicate(string());
239 }
240 #endif
241
242 // Grab the StringTable_lock before getting the_table() because it could
243 // change at safepoint.
244 oop added_or_found;
245 {
246 MutexLocker ml(StringTable_lock, THREAD);
247 // Otherwise, add to symbol to table
248 added_or_found = the_table()->basic_add(index, string, name, len,
249 hashValue, CHECK_NULL);
250 }
251
252 ensure_string_alive(added_or_found);
253
254 return added_or_found;
255 }
256
257 oop StringTable::intern(Symbol* symbol, TRAPS) {
258 if (symbol == NULL) return NULL;
259 ResourceMark rm(THREAD);
260 int length;
261 jchar* chars = symbol->as_unicode(length);
262 Handle string;
263 oop result = intern(string, chars, length, CHECK_NULL);
264 return result;
265 }
266
267
268 oop StringTable::intern(oop string, TRAPS)
269 {
270 if (string == NULL) return NULL;
271 ResourceMark rm(THREAD);
272 int length;
273 Handle h_string (THREAD, string);
274 jchar* chars = java_lang_String::as_unicode_string(string, length, CHECK_NULL);
275 oop result = intern(h_string, chars, length, CHECK_NULL);
276 return result;
277 }
278
279
280 oop StringTable::intern(const char* utf8_string, TRAPS) {
281 if (utf8_string == NULL) return NULL;
282 ResourceMark rm(THREAD);
283 int length = UTF8::unicode_length(utf8_string);
284 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
285 UTF8::convert_to_unicode(utf8_string, chars, length);
286 Handle string;
287 oop result = intern(string, chars, length, CHECK_NULL);
288 return result;
289 }
290
291 void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
292 buckets_unlink_or_oops_do(is_alive, f, 0, the_table()->table_size(), processed, removed);
293 }
294
295 void StringTable::possibly_parallel_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
296 // Readers of the table are unlocked, so we should only be removing
297 // entries at a safepoint.
298 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
299 const int limit = the_table()->table_size();
300
301 for (;;) {
302 // Grab next set of buckets to scan
303 int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
304 if (start_idx >= limit) {
305 // End of table
306 break;
307 }
308
309 int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
310 buckets_unlink_or_oops_do(is_alive, f, start_idx, end_idx, processed, removed);
311 }
312 }
313
314 void StringTable::buckets_oops_do(OopClosure* f, int start_idx, int end_idx) {
315 const int limit = the_table()->table_size();
316
317 assert(0 <= start_idx && start_idx <= limit,
318 "start_idx (%d) is out of bounds", start_idx);
319 assert(0 <= end_idx && end_idx <= limit,
320 "end_idx (%d) is out of bounds", end_idx);
321 assert(start_idx <= end_idx,
322 "Index ordering: start_idx=%d, end_idx=%d",
323 start_idx, end_idx);
324
325 for (int i = start_idx; i < end_idx; i += 1) {
326 HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
327 while (entry != NULL) {
328 assert(!entry->is_shared(), "CDS not used for the StringTable");
329
330 f->do_oop((oop*)entry->literal_addr());
331
332 entry = entry->next();
333 }
334 }
335 }
336
337 void StringTable::buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, int* processed, int* removed) {
338 const int limit = the_table()->table_size();
339
340 assert(0 <= start_idx && start_idx <= limit,
341 "start_idx (%d) is out of bounds", start_idx);
342 assert(0 <= end_idx && end_idx <= limit,
343 "end_idx (%d) is out of bounds", end_idx);
344 assert(start_idx <= end_idx,
345 "Index ordering: start_idx=%d, end_idx=%d",
346 start_idx, end_idx);
347
348 for (int i = start_idx; i < end_idx; ++i) {
349 HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i);
350 HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
351 while (entry != NULL) {
352 assert(!entry->is_shared(), "CDS not used for the StringTable");
353
354 if (is_alive->do_object_b(entry->literal())) {
355 if (f != NULL) {
356 f->do_oop((oop*)entry->literal_addr());
357 }
358 p = entry->next_addr();
359 } else {
360 *p = entry->next();
361 the_table()->free_entry(entry);
362 (*removed)++;
363 }
364 (*processed)++;
365 entry = *p;
366 }
367 }
368 }
369
370 void StringTable::oops_do(OopClosure* f) {
371 buckets_oops_do(f, 0, the_table()->table_size());
372 }
373
374 void StringTable::possibly_parallel_oops_do(OopClosure* f) {
375 const int limit = the_table()->table_size();
376
377 for (;;) {
378 // Grab next set of buckets to scan
379 int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
380 if (start_idx >= limit) {
381 // End of table
382 break;
383 }
384
385 int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
386 buckets_oops_do(f, start_idx, end_idx);
387 }
388 }
389
390 // This verification is part of Universe::verify() and needs to be quick.
391 // See StringTable::verify_and_compare() below for exhaustive verification.
392 void StringTable::verify() {
393 for (int i = 0; i < the_table()->table_size(); ++i) {
394 HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
395 for ( ; p != NULL; p = p->next()) {
396 oop s = p->literal();
397 guarantee(s != NULL, "interned string is NULL");
398 unsigned int h = java_lang_String::hash_string(s);
399 guarantee(p->hash() == h, "broken hash in string table entry");
400 guarantee(the_table()->hash_to_index(h) == i,
401 "wrong index in string table");
402 }
403 }
404 }
405
406 void StringTable::dump(outputStream* st, bool verbose) {
407 if (!verbose) {
408 the_table()->dump_table(st, "StringTable");
409 } else {
410 Thread* THREAD = Thread::current();
411 st->print_cr("VERSION: 1.1");
412 for (int i = 0; i < the_table()->table_size(); ++i) {
413 HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
414 for ( ; p != NULL; p = p->next()) {
415 oop s = p->literal();
416 typeArrayOop value = java_lang_String::value(s);
417 int length = java_lang_String::length(s);
418 bool is_latin1 = java_lang_String::is_latin1(s);
419
420 if (length <= 0) {
421 st->print("%d: ", length);
422 } else {
423 ResourceMark rm(THREAD);
424 int utf8_length;
425 char* utf8_string;
426
427 if (!is_latin1) {
428 jchar* chars = value->char_at_addr(0);
429 utf8_length = UNICODE::utf8_length(chars, length);
430 utf8_string = UNICODE::as_utf8(chars, length);
431 } else {
432 jbyte* bytes = value->byte_at_addr(0);
433 utf8_length = UNICODE::utf8_length(bytes, length);
434 utf8_string = UNICODE::as_utf8(bytes, length);
435 }
436
437 st->print("%d: ", utf8_length);
438 HashtableTextDump::put_utf8(st, utf8_string, utf8_length);
439 }
440 st->cr();
441 }
442 }
443 }
444 }
445
446 StringTable::VerifyRetTypes StringTable::compare_entries(
447 int bkt1, int e_cnt1,
448 HashtableEntry<oop, mtSymbol>* e_ptr1,
449 int bkt2, int e_cnt2,
450 HashtableEntry<oop, mtSymbol>* e_ptr2) {
451 // These entries are sanity checked by verify_and_compare_entries()
452 // before this function is called.
453 oop str1 = e_ptr1->literal();
454 oop str2 = e_ptr2->literal();
455
456 if (str1 == str2) {
457 tty->print_cr("ERROR: identical oop values (0x" PTR_FORMAT ") "
458 "in entry @ bucket[%d][%d] and entry @ bucket[%d][%d]",
459 p2i(str1), bkt1, e_cnt1, bkt2, e_cnt2);
460 return _verify_fail_continue;
461 }
462
463 if (java_lang_String::equals(str1, str2)) {
464 tty->print_cr("ERROR: identical String values in entry @ "
465 "bucket[%d][%d] and entry @ bucket[%d][%d]",
466 bkt1, e_cnt1, bkt2, e_cnt2);
467 return _verify_fail_continue;
468 }
469
470 return _verify_pass;
471 }
472
473 StringTable::VerifyRetTypes StringTable::verify_entry(int bkt, int e_cnt,
474 HashtableEntry<oop, mtSymbol>* e_ptr,
475 StringTable::VerifyMesgModes mesg_mode) {
476
477 VerifyRetTypes ret = _verify_pass; // be optimistic
478
479 oop str = e_ptr->literal();
480 if (str == NULL) {
481 if (mesg_mode == _verify_with_mesgs) {
482 tty->print_cr("ERROR: NULL oop value in entry @ bucket[%d][%d]", bkt,
483 e_cnt);
484 }
485 // NULL oop means no more verifications are possible
486 return _verify_fail_done;
487 }
488
489 if (str->klass() != SystemDictionary::String_klass()) {
490 if (mesg_mode == _verify_with_mesgs) {
491 tty->print_cr("ERROR: oop is not a String in entry @ bucket[%d][%d]",
492 bkt, e_cnt);
493 }
494 // not a String means no more verifications are possible
495 return _verify_fail_done;
496 }
497
498 unsigned int h = java_lang_String::hash_string(str);
499 if (e_ptr->hash() != h) {
500 if (mesg_mode == _verify_with_mesgs) {
501 tty->print_cr("ERROR: broken hash value in entry @ bucket[%d][%d], "
502 "bkt_hash=%d, str_hash=%d", bkt, e_cnt, e_ptr->hash(), h);
503 }
504 ret = _verify_fail_continue;
505 }
506
507 if (the_table()->hash_to_index(h) != bkt) {
508 if (mesg_mode == _verify_with_mesgs) {
509 tty->print_cr("ERROR: wrong index value for entry @ bucket[%d][%d], "
510 "str_hash=%d, hash_to_index=%d", bkt, e_cnt, h,
511 the_table()->hash_to_index(h));
512 }
513 ret = _verify_fail_continue;
514 }
515
516 return ret;
517 }
518
519 // See StringTable::verify() above for the quick verification that is
520 // part of Universe::verify(). This verification is exhaustive and
521 // reports on every issue that is found. StringTable::verify() only
522 // reports on the first issue that is found.
523 //
524 // StringTable::verify_entry() checks:
525 // - oop value != NULL (same as verify())
526 // - oop value is a String
527 // - hash(String) == hash in entry (same as verify())
528 // - index for hash == index of entry (same as verify())
529 //
530 // StringTable::compare_entries() checks:
531 // - oops are unique across all entries
532 // - String values are unique across all entries
533 //
534 int StringTable::verify_and_compare_entries() {
535 assert(StringTable_lock->is_locked(), "sanity check");
536
537 int fail_cnt = 0;
538
539 // first, verify all the entries individually:
540 for (int bkt = 0; bkt < the_table()->table_size(); bkt++) {
541 HashtableEntry<oop, mtSymbol>* e_ptr = the_table()->bucket(bkt);
542 for (int e_cnt = 0; e_ptr != NULL; e_ptr = e_ptr->next(), e_cnt++) {
543 VerifyRetTypes ret = verify_entry(bkt, e_cnt, e_ptr, _verify_with_mesgs);
544 if (ret != _verify_pass) {
545 fail_cnt++;
546 }
547 }
548 }
549
550 // Optimization: if the above check did not find any failures, then
551 // the comparison loop below does not need to call verify_entry()
552 // before calling compare_entries(). If there were failures, then we
553 // have to call verify_entry() to see if the entry can be passed to
554 // compare_entries() safely. When we call verify_entry() in the loop
555 // below, we do so quietly to void duplicate messages and we don't
556 // increment fail_cnt because the failures have already been counted.
557 bool need_entry_verify = (fail_cnt != 0);
558
559 // second, verify all entries relative to each other:
560 for (int bkt1 = 0; bkt1 < the_table()->table_size(); bkt1++) {
561 HashtableEntry<oop, mtSymbol>* e_ptr1 = the_table()->bucket(bkt1);
562 for (int e_cnt1 = 0; e_ptr1 != NULL; e_ptr1 = e_ptr1->next(), e_cnt1++) {
563 if (need_entry_verify) {
564 VerifyRetTypes ret = verify_entry(bkt1, e_cnt1, e_ptr1,
565 _verify_quietly);
566 if (ret == _verify_fail_done) {
567 // cannot use the current entry to compare against other entries
568 continue;
569 }
570 }
571
572 for (int bkt2 = bkt1; bkt2 < the_table()->table_size(); bkt2++) {
573 HashtableEntry<oop, mtSymbol>* e_ptr2 = the_table()->bucket(bkt2);
574 int e_cnt2;
575 for (e_cnt2 = 0; e_ptr2 != NULL; e_ptr2 = e_ptr2->next(), e_cnt2++) {
576 if (bkt1 == bkt2 && e_cnt2 <= e_cnt1) {
577 // skip the entries up to and including the one that
578 // we're comparing against
579 continue;
580 }
581
582 if (need_entry_verify) {
583 VerifyRetTypes ret = verify_entry(bkt2, e_cnt2, e_ptr2,
584 _verify_quietly);
585 if (ret == _verify_fail_done) {
586 // cannot compare against this entry
587 continue;
588 }
589 }
590
591 // compare two entries, report and count any failures:
592 if (compare_entries(bkt1, e_cnt1, e_ptr1, bkt2, e_cnt2, e_ptr2)
593 != _verify_pass) {
594 fail_cnt++;
595 }
596 }
597 }
598 }
599 }
600 return fail_cnt;
601 }
602
603 // Create a new table and using alternate hash code, populate the new table
604 // with the existing strings. Set flag to use the alternate hash code afterwards.
605 void StringTable::rehash_table() {
606 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
607 // This should never happen with -Xshare:dump but it might in testing mode.
608 if (DumpSharedSpaces) return;
609 StringTable* new_table = new StringTable();
610
611 // Rehash the table
612 the_table()->move_to(new_table);
613
614 // Delete the table and buckets (entries are reused in new table).
615 delete _the_table;
616 // Don't check if we need rehashing until the table gets unbalanced again.
617 // Then rehash with a new global seed.
618 _needs_rehashing = false;
619 _the_table = new_table;
620 }
621
622 // Utility for dumping strings
623 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
624 DCmdWithParser(output, heap),
625 _verbose("-verbose", "Dump the content of each string in the table",
626 "BOOLEAN", false, "false") {
627 _dcmdparser.add_dcmd_option(&_verbose);
628 }
629
630 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
631 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
632 _verbose.value());
633 VMThread::execute(&dumper);
634 }
635
636 int StringtableDCmd::num_arguments() {
637 ResourceMark rm;
638 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
639 if (dcmd != NULL) {
640 DCmdMark mark(dcmd);
641 return dcmd->_dcmdparser.num_arguments();
642 } else {
643 return 0;
644 }
645 }
646
647 // Sharing
648 bool StringTable::copy_shared_string(GrowableArray<MemRegion> *string_space,
649 CompactHashtableWriter* ch_table) {
650 #if INCLUDE_CDS && INCLUDE_ALL_GCS && defined(_LP64) && !defined(_WINDOWS)
651 assert(UseG1GC, "Only support G1 GC");
652 assert(UseCompressedOops && UseCompressedClassPointers,
653 "Only support UseCompressedOops and UseCompressedClassPointers enabled");
654
655 Thread* THREAD = Thread::current();
656 G1CollectedHeap::heap()->begin_archive_alloc_range();
657 for (int i = 0; i < the_table()->table_size(); ++i) {
658 HashtableEntry<oop, mtSymbol>* bucket = the_table()->bucket(i);
659 for ( ; bucket != NULL; bucket = bucket->next()) {
660 oop s = bucket->literal();
661 unsigned int hash = java_lang_String::hash_code(s);
662 if (hash == 0) {
663 continue;
664 }
665
666 // allocate the new 'value' array first
667 typeArrayOop v = java_lang_String::value(s);
668 int v_len = v->size();
669 typeArrayOop new_v;
670 if (G1CollectedHeap::heap()->is_archive_alloc_too_large(v_len)) {
671 continue; // skip the current String. The 'value' array is too large to handle
672 } else {
673 new_v = (typeArrayOop)G1CollectedHeap::heap()->archive_mem_allocate(v_len);
674 if (new_v == NULL) {
675 return false; // allocation failed
676 }
677 }
678 // now allocate the new String object
679 int s_len = s->size();
680 oop new_s = (oop)G1CollectedHeap::heap()->archive_mem_allocate(s_len);
681 if (new_s == NULL) {
682 return false;
683 }
684
685 s->identity_hash();
686 v->identity_hash();
687
688 // copy the objects' data
689 Copy::aligned_disjoint_words((HeapWord*)s, (HeapWord*)new_s, s_len);
690 Copy::aligned_disjoint_words((HeapWord*)v, (HeapWord*)new_v, v_len);
691
692 // adjust the pointer to the 'value' field in the new String oop. Also pre-compute and set the
693 // 'hash' field. That avoids "write" to the shared strings at runtime by the deduplication process.
694 java_lang_String::set_value_raw(new_s, new_v);
695 if (java_lang_String::hash(new_s) == 0) {
696 java_lang_String::set_hash(new_s, hash);
697 }
698
699 // add to the compact table
700 ch_table->add(hash, new_s);
701 }
702 }
703
704 G1CollectedHeap::heap()->end_archive_alloc_range(string_space, os::vm_allocation_granularity());
705 assert(string_space->length() <= 2, "sanity");
706 #endif
707 return true;
708 }
709
710 bool StringTable::copy_compact_table(char** top, char *end, GrowableArray<MemRegion> *string_space,
711 size_t* space_size) {
712 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
713 if (!(UseG1GC && UseCompressedOops && UseCompressedClassPointers)) {
714 if (PrintSharedSpaces) {
715 tty->print_cr("Shared strings are excluded from the archive as UseG1GC, "
716 "UseCompressedOops and UseCompressedClassPointers are required.");
717 }
718 return true;
719 }
720
721 CompactHashtableWriter ch_table(CompactHashtable<oop, char>::_string_table,
722 the_table()->number_of_entries(),
723 &MetaspaceShared::stats()->string);
724
725 // Copy the interned strings into the "string space" within the java heap
726 if (!copy_shared_string(string_space, &ch_table)) {
727 return false;
728 }
729
730 for (int i = 0; i < string_space->length(); i++) {
731 *space_size += string_space->at(i).byte_size();
732 }
733
734 // Now dump the compact table
735 if (*top + ch_table.get_required_bytes() > end) {
736 // not enough space left
737 return false;
738 }
739 ch_table.dump(top, end);
740 *top = (char*)align_pointer_up(*top, sizeof(void*));
741
742 #endif
743 return true;
744 }
745
746 void StringTable::shared_oops_do(OopClosure* f) {
747 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
748 _shared_table.oops_do(f);
749 #endif
750 }
751
752 const char* StringTable::init_shared_table(FileMapInfo *mapinfo, char *buffer) {
753 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
754 if (mapinfo->space_capacity(MetaspaceShared::first_string) == 0) {
755 // no shared string data
756 return buffer;
757 }
758
759 // initialize the shared table
760 juint *p = (juint*)buffer;
761 const char* end = _shared_table.init(
762 CompactHashtable<oop, char>::_string_table, (char*)p);
763 const char* aligned_end = (const char*)align_pointer_up(end, sizeof(void*));
764
765 if (_ignore_shared_strings) {
766 _shared_table.reset();
767 }
768
769 return aligned_end;
770 #endif
771
772 return buffer;
773 }