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 }