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/symbolTable.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 40 // -------------------------------------------------------------------------- 41 // the number of buckets a thread claims 42 const int ClaimChunkSize = 32; 43 44 SymbolTable* SymbolTable::_the_table = NULL; 45 // Static arena for symbols that are not deallocated 46 Arena* SymbolTable::_arena = NULL; 47 bool SymbolTable::_needs_rehashing = false; 48 bool SymbolTable::_lookup_shared_first = false; 49 50 CompactHashtable<Symbol*, char> SymbolTable::_shared_table; 51 52 Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) { 53 assert (len <= Symbol::max_length(), "should be checked by caller"); 54 55 Symbol* sym; 56 57 if (DumpSharedSpaces) { 58 // Allocate all symbols to CLD shared metaspace 59 sym = new (len, ClassLoaderData::the_null_class_loader_data(), THREAD) Symbol(name, len, PERM_REFCOUNT); 60 } else if (c_heap) { 61 // refcount starts as 1 62 sym = new (len, THREAD) Symbol(name, len, 1); 63 assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted"); 64 } else { 65 // Allocate to global arena 66 sym = new (len, arena(), THREAD) Symbol(name, len, PERM_REFCOUNT); 67 } 68 return sym; 69 } 70 71 void SymbolTable::initialize_symbols(int arena_alloc_size) { 72 // Initialize the arena for global symbols, size passed in depends on CDS. 73 if (arena_alloc_size == 0) { 74 _arena = new (mtSymbol) Arena(mtSymbol); 75 } else { 76 _arena = new (mtSymbol) Arena(mtSymbol, arena_alloc_size); 77 } 78 } 79 80 // Call function for all symbols in the symbol table. 81 void SymbolTable::symbols_do(SymbolClosure *cl) { 82 // all symbols from shared table 83 _shared_table.symbols_do(cl); 84 85 // all symbols from the dynamic table 86 const int n = the_table()->table_size(); 87 for (int i = 0; i < n; i++) { 88 for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); 89 p != NULL; 90 p = p->next()) { 91 cl->do_symbol(p->literal_addr()); 92 } 93 } 94 } 95 96 int SymbolTable::_symbols_removed = 0; 97 int SymbolTable::_symbols_counted = 0; 98 volatile int SymbolTable::_parallel_claimed_idx = 0; 99 100 void SymbolTable::buckets_unlink(int start_idx, int end_idx, int* processed, int* removed) { 101 for (int i = start_idx; i < end_idx; ++i) { 102 HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i); 103 HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i); 104 while (entry != NULL) { 105 // Shared entries are normally at the end of the bucket and if we run into 106 // a shared entry, then there is nothing more to remove. However, if we 107 // have rehashed the table, then the shared entries are no longer at the 108 // end of the bucket. 109 if (entry->is_shared() && !use_alternate_hashcode()) { 110 break; 111 } 112 Symbol* s = entry->literal(); 113 (*processed)++; 114 assert(s != NULL, "just checking"); 115 // If reference count is zero, remove. 116 if (s->refcount() == 0) { 117 assert(!entry->is_shared(), "shared entries should be kept live"); 118 delete s; 119 (*removed)++; 120 *p = entry->next(); 121 the_table()->free_entry(entry); 122 } else { 123 p = entry->next_addr(); 124 } 125 // get next entry 126 entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p); 127 } 128 } 129 } 130 131 // Remove unreferenced symbols from the symbol table 132 // This is done late during GC. 133 void SymbolTable::unlink(int* processed, int* removed) { 134 size_t memory_total = 0; 135 buckets_unlink(0, the_table()->table_size(), processed, removed); 136 _symbols_removed += *removed; 137 _symbols_counted += *processed; 138 } 139 140 void SymbolTable::possibly_parallel_unlink(int* processed, int* removed) { 141 const int limit = the_table()->table_size(); 142 143 size_t memory_total = 0; 144 145 for (;;) { 146 // Grab next set of buckets to scan 147 int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize; 148 if (start_idx >= limit) { 149 // End of table 150 break; 151 } 152 153 int end_idx = MIN2(limit, start_idx + ClaimChunkSize); 154 buckets_unlink(start_idx, end_idx, processed, removed); 155 } 156 Atomic::add(*processed, &_symbols_counted); 157 Atomic::add(*removed, &_symbols_removed); 158 } 159 160 // Create a new table and using alternate hash code, populate the new table 161 // with the existing strings. Set flag to use the alternate hash code afterwards. 162 void SymbolTable::rehash_table() { 163 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 164 // This should never happen with -Xshare:dump but it might in testing mode. 165 if (DumpSharedSpaces) return; 166 // Create a new symbol table 167 SymbolTable* new_table = new SymbolTable(); 168 169 the_table()->move_to(new_table); 170 171 // Delete the table and buckets (entries are reused in new table). 172 delete _the_table; 173 // Don't check if we need rehashing until the table gets unbalanced again. 174 // Then rehash with a new global seed. 175 _needs_rehashing = false; 176 _the_table = new_table; 177 } 178 179 // Lookup a symbol in a bucket. 180 181 Symbol* SymbolTable::lookup_dynamic(int index, const char* name, 182 int len, unsigned int hash) { 183 int count = 0; 184 for (HashtableEntry<Symbol*, mtSymbol>* e = bucket(index); e != NULL; e = e->next()) { 185 count++; // count all entries in this bucket, not just ones with same hash 186 if (e->hash() == hash) { 187 Symbol* sym = e->literal(); 188 if (sym->equals(name, len)) { 189 // something is referencing this symbol now. 190 sym->increment_refcount(); 191 return sym; 192 } 193 } 194 } 195 // If the bucket size is too deep check if this hash code is insufficient. 196 if (count >= rehash_count && !needs_rehashing()) { 197 _needs_rehashing = check_rehash_table(count); 198 } 199 return NULL; 200 } 201 202 Symbol* SymbolTable::lookup_shared(const char* name, 203 int len, unsigned int hash) { 204 return _shared_table.lookup(name, hash, len); 205 } 206 207 Symbol* SymbolTable::lookup(int index, const char* name, 208 int len, unsigned int hash) { 209 Symbol* sym; 210 if (_lookup_shared_first) { 211 sym = lookup_shared(name, len, hash); 212 if (sym != NULL) { 213 return sym; 214 } 215 _lookup_shared_first = false; 216 return lookup_dynamic(index, name, len, hash); 217 } else { 218 sym = lookup_dynamic(index, name, len, hash); 219 if (sym != NULL) { 220 return sym; 221 } 222 sym = lookup_shared(name, len, hash); 223 if (sym != NULL) { 224 _lookup_shared_first = true; 225 } 226 return sym; 227 } 228 } 229 230 // Pick hashing algorithm. 231 unsigned int SymbolTable::hash_symbol(const char* s, int len) { 232 return use_alternate_hashcode() ? 233 AltHashing::murmur3_32(seed(), (const jbyte*)s, len) : 234 java_lang_String::hash_code((const jbyte*)s, len); 235 } 236 237 238 // We take care not to be blocking while holding the 239 // SymbolTable_lock. Otherwise, the system might deadlock, since the 240 // symboltable is used during compilation (VM_thread) The lock free 241 // synchronization is simplified by the fact that we do not delete 242 // entries in the symbol table during normal execution (only during 243 // safepoints). 244 245 Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) { 246 unsigned int hashValue = hash_symbol(name, len); 247 int index = the_table()->hash_to_index(hashValue); 248 249 Symbol* s = the_table()->lookup(index, name, len, hashValue); 250 251 // Found 252 if (s != NULL) return s; 253 254 // Grab SymbolTable_lock first. 255 MutexLocker ml(SymbolTable_lock, THREAD); 256 257 // Otherwise, add to symbol to table 258 return the_table()->basic_add(index, (u1*)name, len, hashValue, true, THREAD); 259 } 260 261 Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) { 262 char* buffer; 263 int index, len; 264 unsigned int hashValue; 265 char* name; 266 { 267 debug_only(No_Safepoint_Verifier nsv;) 268 269 name = (char*)sym->base() + begin; 270 len = end - begin; 271 hashValue = hash_symbol(name, len); 272 index = the_table()->hash_to_index(hashValue); 273 Symbol* s = the_table()->lookup(index, name, len, hashValue); 274 275 // Found 276 if (s != NULL) return s; 277 } 278 279 // Otherwise, add to symbol to table. Copy to a C string first. 280 char stack_buf[128]; 281 ResourceMark rm(THREAD); 282 if (len <= 128) { 283 buffer = stack_buf; 284 } else { 285 buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len); 286 } 287 for (int i=0; i<len; i++) { 288 buffer[i] = name[i]; 289 } 290 // Make sure there is no safepoint in the code above since name can't move. 291 // We can't include the code in No_Safepoint_Verifier because of the 292 // ResourceMark. 293 294 // Grab SymbolTable_lock first. 295 MutexLocker ml(SymbolTable_lock, THREAD); 296 297 return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, THREAD); 298 } 299 300 Symbol* SymbolTable::lookup_only(const char* name, int len, 301 unsigned int& hash) { 302 hash = hash_symbol(name, len); 303 int index = the_table()->hash_to_index(hash); 304 305 Symbol* s = the_table()->lookup(index, name, len, hash); 306 return s; 307 } 308 309 // Look up the address of the literal in the SymbolTable for this Symbol* 310 // Do not create any new symbols 311 // Do not increment the reference count to keep this alive 312 Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){ 313 unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length()); 314 int index = the_table()->hash_to_index(hash); 315 316 for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(index); e != NULL; e = e->next()) { 317 if (e->hash() == hash) { 318 Symbol* literal_sym = e->literal(); 319 if (sym == literal_sym) { 320 return e->literal_addr(); 321 } 322 } 323 } 324 return NULL; 325 } 326 327 // Suggestion: Push unicode-based lookup all the way into the hashing 328 // and probing logic, so there is no need for convert_to_utf8 until 329 // an actual new Symbol* is created. 330 Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) { 331 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length); 332 char stack_buf[128]; 333 if (utf8_length < (int) sizeof(stack_buf)) { 334 char* chars = stack_buf; 335 UNICODE::convert_to_utf8(name, utf16_length, chars); 336 return lookup(chars, utf8_length, THREAD); 337 } else { 338 ResourceMark rm(THREAD); 339 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);; 340 UNICODE::convert_to_utf8(name, utf16_length, chars); 341 return lookup(chars, utf8_length, THREAD); 342 } 343 } 344 345 Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length, 346 unsigned int& hash) { 347 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length); 348 char stack_buf[128]; 349 if (utf8_length < (int) sizeof(stack_buf)) { 350 char* chars = stack_buf; 351 UNICODE::convert_to_utf8(name, utf16_length, chars); 352 return lookup_only(chars, utf8_length, hash); 353 } else { 354 ResourceMark rm; 355 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);; 356 UNICODE::convert_to_utf8(name, utf16_length, chars); 357 return lookup_only(chars, utf8_length, hash); 358 } 359 } 360 361 void SymbolTable::add(ClassLoaderData* loader_data, const constantPoolHandle& cp, 362 int names_count, 363 const char** names, int* lengths, int* cp_indices, 364 unsigned int* hashValues, TRAPS) { 365 // Grab SymbolTable_lock first. 366 MutexLocker ml(SymbolTable_lock, THREAD); 367 368 SymbolTable* table = the_table(); 369 bool added = table->basic_add(loader_data, cp, names_count, names, lengths, 370 cp_indices, hashValues, CHECK); 371 if (!added) { 372 // do it the hard way 373 for (int i=0; i<names_count; i++) { 374 int index = table->hash_to_index(hashValues[i]); 375 bool c_heap = !loader_data->is_the_null_class_loader_data(); 376 Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK); 377 cp->symbol_at_put(cp_indices[i], sym); 378 } 379 } 380 } 381 382 Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) { 383 unsigned int hash; 384 Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash); 385 if (result != NULL) { 386 return result; 387 } 388 // Grab SymbolTable_lock first. 389 MutexLocker ml(SymbolTable_lock, THREAD); 390 391 SymbolTable* table = the_table(); 392 int index = table->hash_to_index(hash); 393 return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD); 394 } 395 396 Symbol* SymbolTable::basic_add(int index_arg, u1 *name, int len, 397 unsigned int hashValue_arg, bool c_heap, TRAPS) { 398 assert(!Universe::heap()->is_in_reserved(name), 399 "proposed name of symbol must be stable"); 400 401 // Don't allow symbols to be created which cannot fit in a Symbol*. 402 if (len > Symbol::max_length()) { 403 THROW_MSG_0(vmSymbols::java_lang_InternalError(), 404 "name is too long to represent"); 405 } 406 407 // Cannot hit a safepoint in this function because the "this" pointer can move. 408 No_Safepoint_Verifier nsv; 409 410 // Check if the symbol table has been rehashed, if so, need to recalculate 411 // the hash value and index. 412 unsigned int hashValue; 413 int index; 414 if (use_alternate_hashcode()) { 415 hashValue = hash_symbol((const char*)name, len); 416 index = hash_to_index(hashValue); 417 } else { 418 hashValue = hashValue_arg; 419 index = index_arg; 420 } 421 422 // Since look-up was done lock-free, we need to check if another 423 // thread beat us in the race to insert the symbol. 424 Symbol* test = lookup(index, (char*)name, len, hashValue); 425 if (test != NULL) { 426 // A race occurred and another thread introduced the symbol. 427 assert(test->refcount() != 0, "lookup should have incremented the count"); 428 return test; 429 } 430 431 // Create a new symbol. 432 Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL); 433 assert(sym->equals((char*)name, len), "symbol must be properly initialized"); 434 435 HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym); 436 add_entry(index, entry); 437 return sym; 438 } 439 440 // This version of basic_add adds symbols in batch from the constant pool 441 // parsing. 442 bool SymbolTable::basic_add(ClassLoaderData* loader_data, const constantPoolHandle& cp, 443 int names_count, 444 const char** names, int* lengths, 445 int* cp_indices, unsigned int* hashValues, 446 TRAPS) { 447 448 // Check symbol names are not too long. If any are too long, don't add any. 449 for (int i = 0; i< names_count; i++) { 450 if (lengths[i] > Symbol::max_length()) { 451 THROW_MSG_0(vmSymbols::java_lang_InternalError(), 452 "name is too long to represent"); 453 } 454 } 455 456 // Cannot hit a safepoint in this function because the "this" pointer can move. 457 No_Safepoint_Verifier nsv; 458 459 for (int i=0; i<names_count; i++) { 460 // Check if the symbol table has been rehashed, if so, need to recalculate 461 // the hash value. 462 unsigned int hashValue; 463 if (use_alternate_hashcode()) { 464 hashValue = hash_symbol(names[i], lengths[i]); 465 } else { 466 hashValue = hashValues[i]; 467 } 468 // Since look-up was done lock-free, we need to check if another 469 // thread beat us in the race to insert the symbol. 470 int index = hash_to_index(hashValue); 471 Symbol* test = lookup(index, names[i], lengths[i], hashValue); 472 if (test != NULL) { 473 // A race occurred and another thread introduced the symbol, this one 474 // will be dropped and collected. Use test instead. 475 cp->symbol_at_put(cp_indices[i], test); 476 assert(test->refcount() != 0, "lookup should have incremented the count"); 477 } else { 478 // Create a new symbol. The null class loader is never unloaded so these 479 // are allocated specially in a permanent arena. 480 bool c_heap = !loader_data->is_the_null_class_loader_data(); 481 Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false)); 482 assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized"); // why wouldn't it be??? 483 HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym); 484 add_entry(index, entry); 485 cp->symbol_at_put(cp_indices[i], sym); 486 } 487 } 488 return true; 489 } 490 491 492 void SymbolTable::verify() { 493 for (int i = 0; i < the_table()->table_size(); ++i) { 494 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); 495 for ( ; p != NULL; p = p->next()) { 496 Symbol* s = (Symbol*)(p->literal()); 497 guarantee(s != NULL, "symbol is NULL"); 498 unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length()); 499 guarantee(p->hash() == h, "broken hash in symbol table entry"); 500 guarantee(the_table()->hash_to_index(h) == i, 501 "wrong index in symbol table"); 502 } 503 } 504 } 505 506 void SymbolTable::dump(outputStream* st, bool verbose) { 507 if (!verbose) { 508 the_table()->dump_table(st, "SymbolTable"); 509 } else { 510 st->print_cr("VERSION: 1.0"); 511 for (int i = 0; i < the_table()->table_size(); ++i) { 512 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); 513 for ( ; p != NULL; p = p->next()) { 514 Symbol* s = (Symbol*)(p->literal()); 515 const char* utf8_string = (const char*)s->bytes(); 516 int utf8_length = s->utf8_length(); 517 st->print("%d %d: ", utf8_length, s->refcount()); 518 HashtableTextDump::put_utf8(st, utf8_string, utf8_length); 519 st->cr(); 520 } 521 } 522 } 523 } 524 525 bool SymbolTable::copy_compact_table(char** top, char*end) { 526 #if INCLUDE_CDS 527 CompactHashtableWriter ch_table(CompactHashtable<Symbol*, char>::_symbol_table, 528 the_table()->number_of_entries(), 529 &MetaspaceShared::stats()->symbol); 530 if (*top + ch_table.get_required_bytes() > end) { 531 // not enough space left 532 return false; 533 } 534 535 for (int i = 0; i < the_table()->table_size(); ++i) { 536 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); 537 for ( ; p != NULL; p = p->next()) { 538 Symbol* s = (Symbol*)(p->literal()); 539 unsigned int fixed_hash = hash_symbol((char*)s->bytes(), s->utf8_length()); 540 assert(fixed_hash == p->hash(), "must not rehash during dumping"); 541 ch_table.add(fixed_hash, s); 542 } 543 } 544 545 ch_table.dump(top, end); 546 547 *top = (char*)align_pointer_up(*top, sizeof(void*)); 548 #endif 549 return true; 550 } 551 552 const char* SymbolTable::init_shared_table(const char* buffer) { 553 const char* end = _shared_table.init( 554 CompactHashtable<Symbol*, char>::_symbol_table, buffer); 555 return (const char*)align_pointer_up(end, sizeof(void*)); 556 } 557 558 //--------------------------------------------------------------------------- 559 // Non-product code 560 561 #ifndef PRODUCT 562 563 void SymbolTable::print_histogram() { 564 MutexLocker ml(SymbolTable_lock); 565 const int results_length = 100; 566 int counts[results_length]; 567 int sizes[results_length]; 568 int i,j; 569 570 // initialize results to zero 571 for (j = 0; j < results_length; j++) { 572 counts[j] = 0; 573 sizes[j] = 0; 574 } 575 576 int total_size = 0; 577 int total_count = 0; 578 int total_length = 0; 579 int max_length = 0; 580 int out_of_range_count = 0; 581 int out_of_range_size = 0; 582 for (i = 0; i < the_table()->table_size(); i++) { 583 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); 584 for ( ; p != NULL; p = p->next()) { 585 int size = p->literal()->size(); 586 int len = p->literal()->utf8_length(); 587 if (len < results_length) { 588 counts[len]++; 589 sizes[len] += size; 590 } else { 591 out_of_range_count++; 592 out_of_range_size += size; 593 } 594 total_count++; 595 total_size += size; 596 total_length += len; 597 max_length = MAX2(max_length, len); 598 } 599 } 600 tty->print_cr("Symbol Table Histogram:"); 601 tty->print_cr(" Total number of symbols %7d", total_count); 602 tty->print_cr(" Total size in memory %7dK", 603 (total_size*HeapWordSize)/1024); 604 tty->print_cr(" Total counted %7d", _symbols_counted); 605 tty->print_cr(" Total removed %7d", _symbols_removed); 606 if (_symbols_counted > 0) { 607 tty->print_cr(" Percent removed %3.2f", 608 ((float)_symbols_removed/(float)_symbols_counted)* 100); 609 } 610 tty->print_cr(" Reference counts %7d", Symbol::_total_count); 611 tty->print_cr(" Symbol arena used " SIZE_FORMAT_W(7) "K", arena()->used()/1024); 612 tty->print_cr(" Symbol arena size " SIZE_FORMAT_W(7) "K", arena()->size_in_bytes()/1024); 613 tty->print_cr(" Total symbol length %7d", total_length); 614 tty->print_cr(" Maximum symbol length %7d", max_length); 615 tty->print_cr(" Average symbol length %7.2f", ((float) total_length / (float) total_count)); 616 tty->print_cr(" Symbol length histogram:"); 617 tty->print_cr(" %6s %10s %10s", "Length", "#Symbols", "Size"); 618 for (i = 0; i < results_length; i++) { 619 if (counts[i] > 0) { 620 tty->print_cr(" %6d %10d %10dK", i, counts[i], (sizes[i]*HeapWordSize)/1024); 621 } 622 } 623 tty->print_cr(" >=%6d %10d %10dK\n", results_length, 624 out_of_range_count, (out_of_range_size*HeapWordSize)/1024); 625 } 626 627 void SymbolTable::print() { 628 for (int i = 0; i < the_table()->table_size(); ++i) { 629 HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i); 630 HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i); 631 if (entry != NULL) { 632 while (entry != NULL) { 633 tty->print(PTR_FORMAT " ", p2i(entry->literal())); 634 entry->literal()->print(); 635 tty->print(" %d", entry->literal()->refcount()); 636 p = entry->next_addr(); 637 entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p); 638 } 639 tty->cr(); 640 } 641 } 642 } 643 #endif // PRODUCT 644 645 646 // Utility for dumping symbols 647 SymboltableDCmd::SymboltableDCmd(outputStream* output, bool heap) : 648 DCmdWithParser(output, heap), 649 _verbose("-verbose", "Dump the content of each symbol in the table", 650 "BOOLEAN", false, "false") { 651 _dcmdparser.add_dcmd_option(&_verbose); 652 } 653 654 void SymboltableDCmd::execute(DCmdSource source, TRAPS) { 655 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSymbols, 656 _verbose.value()); 657 VMThread::execute(&dumper); 658 } 659 660 int SymboltableDCmd::num_arguments() { 661 ResourceMark rm; 662 SymboltableDCmd* dcmd = new SymboltableDCmd(NULL, false); 663 if (dcmd != NULL) { 664 DCmdMark mark(dcmd); 665 return dcmd->_dcmdparser.num_arguments(); 666 } else { 667 return 0; 668 } 669 } 670 671 #ifndef PRODUCT 672 // Internal test of TempNewSymbol 673 void Test_TempNewSymbol() { 674 Thread* THREAD = Thread::current(); 675 Symbol* sym = SymbolTable::new_symbol("abc", CATCH); 676 TempNewSymbol ss = sym; 677 assert(ss->refcount() == 1, "only one abc"); 678 assert(ss->refcount() == sym->refcount(), "should match TempNewSymbol"); 679 680 Symbol* sym1 = SymbolTable::new_symbol("efg", CATCH); 681 Symbol* sym2 = SymbolTable::new_symbol("hij", CATCH); 682 TempNewSymbol s1 = sym1; 683 TempNewSymbol s2 = sym2; 684 assert(s1->refcount() == 1, "one efg"); 685 assert(s2->refcount() == 1, "one hij"); 686 687 // Assignment operator 688 s1 = s2; 689 assert(sym2->refcount() == 2, "should be two hij"); 690 assert(sym1->refcount() == 0, "should be no efg"); 691 692 s1 = ss; // s1 is abc 693 assert(s1->refcount() == 2, "should be two abc (s1 and ss)"); 694 assert(sym2->refcount() == 1, "should only have one hij now (s2)"); 695 696 s1 = s1; // self assignment 697 assert(s1->refcount() == 2, "should still be two abc (s1 and ss)"); 698 699 TempNewSymbol s3; 700 s3 = SymbolTable::new_symbol("klm", CATCH); 701 assert(s3->refcount() == 1, "only one klm now"); 702 } 703 #endif // PRODUCT