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.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 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
47
48 // the number of buckets a thread claims
49 const int ClaimChunkSize = 32;
50
51 #ifdef ASSERT
52 class StableMemoryChecker : public StackObj {
53 enum { _bufsize = wordSize*4 };
54
55 address _region;
56 jint _size;
57 u1 _save_buf[_bufsize];
58
59 int sample(u1* save_buf) {
60 if (_size <= _bufsize) {
61 memcpy(save_buf, _region, _size);
62 return _size;
63 } else {
64 // copy head and tail
65 memcpy(&save_buf[0], _region, _bufsize/2);
66 memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
67 return (_bufsize/2)*2;
68 }
69 }
70
71 public:
72 StableMemoryChecker(const void* region, jint size) {
73 _region = (address) region;
74 _size = size;
75 sample(_save_buf);
76 }
77
78 bool verify() {
79 u1 check_buf[sizeof(_save_buf)];
80 int check_size = sample(check_buf);
81 return (0 == memcmp(_save_buf, check_buf, check_size));
82 }
83
84 void set_region(const void* region) { _region = (address) region; }
85 };
86 #endif
87
88
89 // --------------------------------------------------------------------------
90 StringTable* StringTable::_the_table = NULL;
91 bool StringTable::_ignore_shared_strings = false;
92 bool StringTable::_needs_rehashing = false;
93
94 volatile int StringTable::_parallel_claimed_idx = 0;
95
96 CompactHashtable<oop, char> StringTable::_shared_table;
97
98 // Pick hashing algorithm
99 unsigned int StringTable::hash_string(const jchar* s, int len) {
100 return use_alternate_hashcode() ? AltHashing::murmur3_32(seed(), s, len) :
101 java_lang_String::hash_code(s, len);
102 }
103
104 oop StringTable::lookup_shared(jchar* name, int len) {
105 // java_lang_String::hash_code() was used to compute hash values in the shared table. Don't
106 // use the hash value from StringTable::hash_string() as it might use alternate hashcode.
107 return _shared_table.lookup((const char*)name,
108 java_lang_String::hash_code(name, len), len);
109 }
110
111 oop StringTable::lookup_in_main_table(int index, jchar* name,
112 int len, unsigned int hash) {
113 int count = 0;
114 for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) {
115 count++;
116 if (l->hash() == hash) {
117 if (java_lang_String::equals(l->literal(), name, len)) {
118 return l->literal();
119 }
120 }
121 }
122 // If the bucket size is too deep check if this hash code is insufficient.
123 if (count >= rehash_count && !needs_rehashing()) {
124 _needs_rehashing = check_rehash_table(count);
125 }
126 return NULL;
127 }
128
129
130 oop StringTable::basic_add(int index_arg, Handle string, jchar* name,
131 int len, unsigned int hashValue_arg, TRAPS) {
132
133 assert(java_lang_String::equals(string(), name, len),
134 "string must be properly initialized");
135 // Cannot hit a safepoint in this function because the "this" pointer can move.
136 No_Safepoint_Verifier nsv;
137
138 // Check if the symbol table has been rehashed, if so, need to recalculate
139 // the hash value and index before second lookup.
140 unsigned int hashValue;
141 int index;
142 if (use_alternate_hashcode()) {
143 hashValue = hash_string(name, len);
144 index = hash_to_index(hashValue);
145 } else {
146 hashValue = hashValue_arg;
147 index = index_arg;
148 }
149
150 // Since look-up was done lock-free, we need to check if another
151 // thread beat us in the race to insert the symbol.
152
153 // No need to lookup the shared table from here since the caller (intern()) already did
154 oop test = lookup_in_main_table(index, name, len, hashValue); // calls lookup(u1*, int)
155 if (test != NULL) {
156 // Entry already added
157 return test;
158 }
159
160 HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string());
161 add_entry(index, entry);
162 return string();
163 }
164
165
166 oop StringTable::lookup(Symbol* symbol) {
167 ResourceMark rm;
168 int length;
169 jchar* chars = symbol->as_unicode(length);
170 return lookup(chars, length);
171 }
172
173 // Tell the GC that this string was looked up in the StringTable.
174 static void ensure_string_alive(oop string) {
175 // A lookup in the StringTable could return an object that was previously
176 // considered dead. The SATB part of G1 needs to get notified about this
177 // potential resurrection, otherwise the marking might not find the object.
178 #if INCLUDE_ALL_GCS
179 if (UseG1GC && string != NULL) {
180 G1SATBCardTableModRefBS::enqueue(string);
181 }
182 #endif
183 }
184
185 oop StringTable::lookup(jchar* name, int len) {
186 oop string = lookup_shared(name, len);
187 if (string != NULL) {
188 return string;
189 }
190
191 unsigned int hash = hash_string(name, len);
192 int index = the_table()->hash_to_index(hash);
193 string = the_table()->lookup_in_main_table(index, name, len, hash);
194
195 ensure_string_alive(string);
196
197 return string;
198 }
199
200
201 oop StringTable::intern(Handle string_or_null, jchar* name,
202 int len, TRAPS) {
203 oop found_string = lookup_shared(name, len);
204 if (found_string != NULL) {
205 return found_string;
206 }
207
208 unsigned int hashValue = hash_string(name, len);
209 int index = the_table()->hash_to_index(hashValue);
210 found_string = the_table()->lookup_in_main_table(index, name, len, hashValue);
211
212 // Found
213 if (found_string != NULL) {
214 ensure_string_alive(found_string);
215 return found_string;
216 }
217
218 debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
219 assert(!Universe::heap()->is_in_reserved(name),
220 "proposed name of symbol must be stable");
221
222 Handle string;
223 // try to reuse the string if possible
224 if (!string_or_null.is_null()) {
225 string = string_or_null;
226 } else {
227 string = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
228 }
229
230 #if INCLUDE_ALL_GCS
231 if (G1StringDedup::is_enabled()) {
232 // Deduplicate the string before it is interned. Note that we should never
233 // deduplicate a string after it has been interned. Doing so will counteract
234 // compiler optimizations done on e.g. interned string literals.
235 G1StringDedup::deduplicate(string());
236 }
237 #endif
238
239 // Grab the StringTable_lock before getting the_table() because it could
240 // change at safepoint.
241 oop added_or_found;
242 {
243 MutexLocker ml(StringTable_lock, THREAD);
244 // Otherwise, add to symbol to table
245 added_or_found = the_table()->basic_add(index, string, name, len,
246 hashValue, CHECK_NULL);
247 }
248
249 ensure_string_alive(added_or_found);
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 err_msg("start_idx (%d) is out of bounds", start_idx));
316 assert(0 <= end_idx && end_idx <= limit,
317 err_msg("end_idx (%d) is out of bounds", end_idx));
318 assert(start_idx <= end_idx,
319 err_msg("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 err_msg("start_idx (%d) is out of bounds", start_idx));
339 assert(0 <= end_idx && end_idx <= limit,
340 err_msg("end_idx (%d) is out of bounds", end_idx));
341 assert(start_idx <= end_idx,
342 err_msg("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 offset = java_lang_String::offset(s);
415 int length = java_lang_String::length(s);
416
417 if (length <= 0) {
418 st->print("%d: ", length);
419 } else {
420 ResourceMark rm(THREAD);
421 jchar* chars = (jchar*)value->char_at_addr(offset);
422 int utf8_length = UNICODE::utf8_length(chars, length);
423 char* utf8_string = NEW_RESOURCE_ARRAY(char, utf8_length + 1);
424 UNICODE::convert_to_utf8(chars, length, utf8_string);
425
426 st->print("%d: ", utf8_length);
427 HashtableTextDump::put_utf8(st, utf8_string, utf8_length);
428 }
429 st->cr();
430 }
431 }
432 }
433 }
434
435 StringTable::VerifyRetTypes StringTable::compare_entries(
436 int bkt1, int e_cnt1,
437 HashtableEntry<oop, mtSymbol>* e_ptr1,
438 int bkt2, int e_cnt2,
439 HashtableEntry<oop, mtSymbol>* e_ptr2) {
440 // These entries are sanity checked by verify_and_compare_entries()
441 // before this function is called.
442 oop str1 = e_ptr1->literal();
443 oop str2 = e_ptr2->literal();
444
445 if (str1 == str2) {
446 tty->print_cr("ERROR: identical oop values (0x" PTR_FORMAT ") "
447 "in entry @ bucket[%d][%d] and entry @ bucket[%d][%d]",
448 (void *)str1, bkt1, e_cnt1, bkt2, e_cnt2);
449 return _verify_fail_continue;
450 }
451
452 if (java_lang_String::equals(str1, str2)) {
453 tty->print_cr("ERROR: identical String values in entry @ "
454 "bucket[%d][%d] and entry @ bucket[%d][%d]",
455 bkt1, e_cnt1, bkt2, e_cnt2);
456 return _verify_fail_continue;
457 }
458
459 return _verify_pass;
460 }
461
462 StringTable::VerifyRetTypes StringTable::verify_entry(int bkt, int e_cnt,
463 HashtableEntry<oop, mtSymbol>* e_ptr,
464 StringTable::VerifyMesgModes mesg_mode) {
465
466 VerifyRetTypes ret = _verify_pass; // be optimistic
467
468 oop str = e_ptr->literal();
469 if (str == NULL) {
470 if (mesg_mode == _verify_with_mesgs) {
471 tty->print_cr("ERROR: NULL oop value in entry @ bucket[%d][%d]", bkt,
472 e_cnt);
473 }
474 // NULL oop means no more verifications are possible
475 return _verify_fail_done;
476 }
477
478 if (str->klass() != SystemDictionary::String_klass()) {
479 if (mesg_mode == _verify_with_mesgs) {
480 tty->print_cr("ERROR: oop is not a String in entry @ bucket[%d][%d]",
481 bkt, e_cnt);
482 }
483 // not a String means no more verifications are possible
484 return _verify_fail_done;
485 }
486
487 unsigned int h = java_lang_String::hash_string(str);
488 if (e_ptr->hash() != h) {
489 if (mesg_mode == _verify_with_mesgs) {
490 tty->print_cr("ERROR: broken hash value in entry @ bucket[%d][%d], "
491 "bkt_hash=%d, str_hash=%d", bkt, e_cnt, e_ptr->hash(), h);
492 }
493 ret = _verify_fail_continue;
494 }
495
496 if (the_table()->hash_to_index(h) != bkt) {
497 if (mesg_mode == _verify_with_mesgs) {
498 tty->print_cr("ERROR: wrong index value for entry @ bucket[%d][%d], "
499 "str_hash=%d, hash_to_index=%d", bkt, e_cnt, h,
500 the_table()->hash_to_index(h));
501 }
502 ret = _verify_fail_continue;
503 }
504
505 return ret;
506 }
507
508 // See StringTable::verify() above for the quick verification that is
509 // part of Universe::verify(). This verification is exhaustive and
510 // reports on every issue that is found. StringTable::verify() only
511 // reports on the first issue that is found.
512 //
513 // StringTable::verify_entry() checks:
514 // - oop value != NULL (same as verify())
515 // - oop value is a String
516 // - hash(String) == hash in entry (same as verify())
517 // - index for hash == index of entry (same as verify())
518 //
519 // StringTable::compare_entries() checks:
520 // - oops are unique across all entries
521 // - String values are unique across all entries
522 //
523 int StringTable::verify_and_compare_entries() {
524 assert(StringTable_lock->is_locked(), "sanity check");
525
526 int fail_cnt = 0;
527
528 // first, verify all the entries individually:
529 for (int bkt = 0; bkt < the_table()->table_size(); bkt++) {
530 HashtableEntry<oop, mtSymbol>* e_ptr = the_table()->bucket(bkt);
531 for (int e_cnt = 0; e_ptr != NULL; e_ptr = e_ptr->next(), e_cnt++) {
532 VerifyRetTypes ret = verify_entry(bkt, e_cnt, e_ptr, _verify_with_mesgs);
533 if (ret != _verify_pass) {
534 fail_cnt++;
535 }
536 }
537 }
538
539 // Optimization: if the above check did not find any failures, then
540 // the comparison loop below does not need to call verify_entry()
541 // before calling compare_entries(). If there were failures, then we
542 // have to call verify_entry() to see if the entry can be passed to
543 // compare_entries() safely. When we call verify_entry() in the loop
544 // below, we do so quietly to void duplicate messages and we don't
545 // increment fail_cnt because the failures have already been counted.
546 bool need_entry_verify = (fail_cnt != 0);
547
548 // second, verify all entries relative to each other:
549 for (int bkt1 = 0; bkt1 < the_table()->table_size(); bkt1++) {
550 HashtableEntry<oop, mtSymbol>* e_ptr1 = the_table()->bucket(bkt1);
551 for (int e_cnt1 = 0; e_ptr1 != NULL; e_ptr1 = e_ptr1->next(), e_cnt1++) {
552 if (need_entry_verify) {
553 VerifyRetTypes ret = verify_entry(bkt1, e_cnt1, e_ptr1,
554 _verify_quietly);
555 if (ret == _verify_fail_done) {
556 // cannot use the current entry to compare against other entries
557 continue;
558 }
559 }
560
561 for (int bkt2 = bkt1; bkt2 < the_table()->table_size(); bkt2++) {
562 HashtableEntry<oop, mtSymbol>* e_ptr2 = the_table()->bucket(bkt2);
563 int e_cnt2;
564 for (e_cnt2 = 0; e_ptr2 != NULL; e_ptr2 = e_ptr2->next(), e_cnt2++) {
565 if (bkt1 == bkt2 && e_cnt2 <= e_cnt1) {
566 // skip the entries up to and including the one that
567 // we're comparing against
568 continue;
569 }
570
571 if (need_entry_verify) {
572 VerifyRetTypes ret = verify_entry(bkt2, e_cnt2, e_ptr2,
573 _verify_quietly);
574 if (ret == _verify_fail_done) {
575 // cannot compare against this entry
576 continue;
577 }
578 }
579
580 // compare two entries, report and count any failures:
581 if (compare_entries(bkt1, e_cnt1, e_ptr1, bkt2, e_cnt2, e_ptr2)
582 != _verify_pass) {
583 fail_cnt++;
584 }
585 }
586 }
587 }
588 }
589 return fail_cnt;
590 }
591
592 // Create a new table and using alternate hash code, populate the new table
593 // with the existing strings. Set flag to use the alternate hash code afterwards.
594 void StringTable::rehash_table() {
595 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
596 // This should never happen with -Xshare:dump but it might in testing mode.
597 if (DumpSharedSpaces) return;
598 StringTable* new_table = new StringTable();
599
600 // Rehash the table
601 the_table()->move_to(new_table);
602
603 // Delete the table and buckets (entries are reused in new table).
604 delete _the_table;
605 // Don't check if we need rehashing until the table gets unbalanced again.
606 // Then rehash with a new global seed.
607 _needs_rehashing = false;
608 _the_table = new_table;
609 }
610
611 // Utility for dumping strings
612 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
613 DCmdWithParser(output, heap),
614 _verbose("-verbose", "Dump the content of each string in the table",
615 "BOOLEAN", false, "false") {
616 _dcmdparser.add_dcmd_option(&_verbose);
617 }
618
619 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
620 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
621 _verbose.value());
622 VMThread::execute(&dumper);
623 }
624
625 int StringtableDCmd::num_arguments() {
626 ResourceMark rm;
627 StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
628 if (dcmd != NULL) {
629 DCmdMark mark(dcmd);
630 return dcmd->_dcmdparser.num_arguments();
631 } else {
632 return 0;
633 }
634 }
635
636 // Sharing
637 bool StringTable::copy_shared_string(GrowableArray<MemRegion> *string_space,
638 CompactHashtableWriter* ch_table) {
639 #if INCLUDE_CDS && INCLUDE_ALL_GCS && defined(_LP64) && !defined(_WINDOWS)
640 assert(UseG1GC, "Only support G1 GC");
641 assert(UseCompressedOops && UseCompressedClassPointers,
642 "Only support UseCompressedOops and UseCompressedClassPointers enabled");
643
644 Thread* THREAD = Thread::current();
645 G1CollectedHeap::heap()->begin_archive_alloc_range();
646 for (int i = 0; i < the_table()->table_size(); ++i) {
647 HashtableEntry<oop, mtSymbol>* bucket = the_table()->bucket(i);
648 for ( ; bucket != NULL; bucket = bucket->next()) {
649 oop s = bucket->literal();
650 unsigned int hash = java_lang_String::hash_code(s);
651 if (hash == 0) {
652 continue;
653 }
654
655 // allocate the new 'value' array first
656 typeArrayOop v = java_lang_String::value(s);
657 int v_len = v->size();
658 typeArrayOop new_v;
659 if (G1CollectedHeap::heap()->is_archive_alloc_too_large(v_len)) {
660 continue; // skip the current String. The 'value' array is too large to handle
661 } else {
662 new_v = (typeArrayOop)G1CollectedHeap::heap()->archive_mem_allocate(v_len);
663 if (new_v == NULL) {
664 return false; // allocation failed
665 }
666 }
667 // now allocate the new String object
668 int s_len = s->size();
669 oop new_s = (oop)G1CollectedHeap::heap()->archive_mem_allocate(s_len);
670 if (new_s == NULL) {
671 return false;
672 }
673
674 s->identity_hash();
675 v->identity_hash();
676
677 // copy the objects' data
678 Copy::aligned_disjoint_words((HeapWord*)s, (HeapWord*)new_s, s_len);
679 Copy::aligned_disjoint_words((HeapWord*)v, (HeapWord*)new_v, v_len);
680
681 // adjust the pointer to the 'value' field in the new String oop. Also pre-compute and set the
682 // 'hash' field. That avoids "write" to the shared strings at runtime by the deduplication process.
683 java_lang_String::set_value_raw(new_s, new_v);
684 if (java_lang_String::hash(new_s) == 0) {
685 java_lang_String::set_hash(new_s, hash);
686 }
687
688 // add to the compact table
689 ch_table->add(hash, new_s);
690 }
691 }
692
693 G1CollectedHeap::heap()->end_archive_alloc_range(string_space, os::vm_allocation_granularity());
694 assert(string_space->length() <= 2, "sanity");
695 #endif
696 return true;
697 }
698
699 bool StringTable::copy_compact_table(char** top, char *end, GrowableArray<MemRegion> *string_space,
700 size_t* space_size) {
701 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
702 if (!(UseG1GC && UseCompressedOops && UseCompressedClassPointers)) {
703 if (PrintSharedSpaces) {
704 tty->print_cr("Shared strings are excluded from the archive as UseG1GC, "
705 "UseCompressedOops and UseCompressedClassPointers are required.");
706 }
707 return true;
708 }
709
710 CompactHashtableWriter ch_table(CompactHashtable<oop, char>::_string_table,
711 the_table()->number_of_entries(),
712 &MetaspaceShared::stats()->string);
713
714 // Copy the interned strings into the "string space" within the java heap
715 if (!copy_shared_string(string_space, &ch_table)) {
716 return false;
717 }
718
719 for (int i = 0; i < string_space->length(); i++) {
720 *space_size += string_space->at(i).byte_size();
721 }
722
723 // Now dump the compact table
724 if (*top + ch_table.get_required_bytes() > end) {
725 // not enough space left
726 return false;
727 }
728 ch_table.dump(top, end);
729 *top = (char*)align_pointer_up(*top, sizeof(void*));
730
731 #endif
732 return true;
733 }
734
735 void StringTable::shared_oops_do(OopClosure* f) {
736 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
737 _shared_table.oops_do(f);
738 #endif
739 }
740
741 const char* StringTable::init_shared_table(FileMapInfo *mapinfo, char *buffer) {
742 #if INCLUDE_CDS && defined(_LP64) && !defined(_WINDOWS)
743 if (mapinfo->space_capacity(MetaspaceShared::first_string) == 0) {
744 // no shared string data
745 return buffer;
746 }
747
748 // initialize the shared table
749 juint *p = (juint*)buffer;
750 const char* end = _shared_table.init(
751 CompactHashtable<oop, char>::_string_table, (char*)p);
752 const char* aligned_end = (const char*)align_pointer_up(end, sizeof(void*));
753
754 if (_ignore_shared_strings) {
755 _shared_table.reset();
756 }
757
758 return aligned_end;
759 #endif
760
761 return buffer;
762 }