src/share/vm/classfile/symbolTable.cpp

Fri, 23 Mar 2012 11:16:05 -0400

author
coleenp
date
Fri, 23 Mar 2012 11:16:05 -0400
changeset 3682
fc9d8850ab8b
parent 3427
94ec88ca68e2
child 3865
e9140bf80b4a
permissions
-rw-r--r--

7150058: Allocate symbols from null boot loader to an arena for NMT
Summary: Move symbol allocation to an arena so NMT doesn't have to track them at startup.
Reviewed-by: never, kamg, zgu

duke@435 1 /*
coleenp@3682 2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
duke@435 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435 4 *
duke@435 5 * This code is free software; you can redistribute it and/or modify it
duke@435 6 * under the terms of the GNU General Public License version 2 only, as
duke@435 7 * published by the Free Software Foundation.
duke@435 8 *
duke@435 9 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435 12 * version 2 for more details (a copy is included in the LICENSE file that
duke@435 13 * accompanied this code).
duke@435 14 *
duke@435 15 * You should have received a copy of the GNU General Public License version
duke@435 16 * 2 along with this work; if not, write to the Free Software Foundation,
duke@435 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435 18 *
trims@1907 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907 20 * or visit www.oracle.com if you need additional information or have any
trims@1907 21 * questions.
duke@435 22 *
duke@435 23 */
duke@435 24
stefank@2314 25 #include "precompiled.hpp"
stefank@2314 26 #include "classfile/javaClasses.hpp"
stefank@2314 27 #include "classfile/symbolTable.hpp"
stefank@2314 28 #include "classfile/systemDictionary.hpp"
stefank@2314 29 #include "gc_interface/collectedHeap.inline.hpp"
coleenp@3682 30 #include "memory/allocation.inline.hpp"
stefank@2314 31 #include "memory/filemap.hpp"
stefank@2314 32 #include "memory/gcLocker.inline.hpp"
stefank@2314 33 #include "oops/oop.inline.hpp"
stefank@2314 34 #include "oops/oop.inline2.hpp"
stefank@2314 35 #include "runtime/mutexLocker.hpp"
stefank@2314 36 #include "utilities/hashtable.inline.hpp"
duke@435 37
duke@435 38 // --------------------------------------------------------------------------
duke@435 39
duke@435 40 SymbolTable* SymbolTable::_the_table = NULL;
coleenp@3682 41 // Static arena for symbols that are not deallocated
coleenp@3682 42 Arena* SymbolTable::_arena = NULL;
duke@435 43
coleenp@3682 44 Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) {
coleenp@2497 45 // Don't allow symbols to be created which cannot fit in a Symbol*.
coleenp@2497 46 if (len > Symbol::max_length()) {
coleenp@2497 47 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
coleenp@2497 48 "name is too long to represent");
coleenp@2497 49 }
coleenp@3682 50 Symbol* sym;
coleenp@3682 51 // Allocate symbols in the C heap when dumping shared spaces in case there
coleenp@3682 52 // are temporary symbols we can remove.
coleenp@3682 53 if (c_heap || DumpSharedSpaces) {
coleenp@3682 54 // refcount starts as 1
coleenp@3682 55 sym = new (len, THREAD) Symbol(name, len, 1);
coleenp@3682 56 } else {
coleenp@3682 57 sym = new (len, arena(), THREAD) Symbol(name, len, -1);
coleenp@3682 58 }
coleenp@2497 59 assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
coleenp@2497 60 return sym;
coleenp@2497 61 }
coleenp@2497 62
coleenp@3682 63 void SymbolTable::initialize_symbols(int arena_alloc_size) {
coleenp@3682 64 // Initialize the arena for global symbols, size passed in depends on CDS.
coleenp@3682 65 if (arena_alloc_size == 0) {
coleenp@3682 66 _arena = new Arena();
coleenp@3682 67 } else {
coleenp@3682 68 _arena = new Arena(arena_alloc_size);
coleenp@2497 69 }
coleenp@2497 70 }
coleenp@2497 71
coleenp@2497 72 // Call function for all symbols in the symbol table.
coleenp@2497 73 void SymbolTable::symbols_do(SymbolClosure *cl) {
coleenp@2497 74 const int n = the_table()->table_size();
coleenp@2497 75 for (int i = 0; i < n; i++) {
coleenp@2497 76 for (HashtableEntry<Symbol*>* p = the_table()->bucket(i);
coleenp@2497 77 p != NULL;
coleenp@2497 78 p = p->next()) {
coleenp@2497 79 cl->do_symbol(p->literal_addr());
coleenp@2497 80 }
coleenp@2497 81 }
coleenp@2497 82 }
coleenp@2497 83
coleenp@2497 84 int SymbolTable::symbols_removed = 0;
coleenp@2497 85 int SymbolTable::symbols_counted = 0;
coleenp@2497 86
coleenp@2497 87 // Remove unreferenced symbols from the symbol table
coleenp@3682 88 // This is done late during GC.
coleenp@2497 89 void SymbolTable::unlink() {
coleenp@2497 90 int removed = 0;
coleenp@2497 91 int total = 0;
coleenp@2618 92 size_t memory_total = 0;
coleenp@2497 93 for (int i = 0; i < the_table()->table_size(); ++i) {
coleenp@2497 94 for (HashtableEntry<Symbol*>** p = the_table()->bucket_addr(i); *p != NULL; ) {
coleenp@2497 95 HashtableEntry<Symbol*>* entry = *p;
coleenp@2497 96 if (entry->is_shared()) {
coleenp@2497 97 break;
coleenp@2497 98 }
coleenp@2497 99 Symbol* s = entry->literal();
coleenp@2497 100 memory_total += s->object_size();
coleenp@2497 101 total++;
coleenp@2497 102 assert(s != NULL, "just checking");
coleenp@2497 103 // If reference count is zero, remove.
coleenp@2497 104 if (s->refcount() == 0) {
coleenp@2497 105 delete s;
coleenp@2497 106 removed++;
coleenp@2497 107 *p = entry->next();
coleenp@2497 108 the_table()->free_entry(entry);
coleenp@2497 109 } else {
coleenp@2497 110 p = entry->next_addr();
coleenp@2497 111 }
coleenp@2497 112 }
coleenp@2497 113 }
coleenp@2497 114 symbols_removed += removed;
coleenp@2497 115 symbols_counted += total;
coleenp@2618 116 // Exclude printing for normal PrintGCDetails because people parse
coleenp@2618 117 // this output.
coleenp@2618 118 if (PrintGCDetails && Verbose && WizardMode) {
coleenp@2618 119 gclog_or_tty->print(" [Symbols=%d size=" SIZE_FORMAT "K] ", total,
coleenp@2497 120 (memory_total*HeapWordSize)/1024);
coleenp@2497 121 }
coleenp@2497 122 }
coleenp@2497 123
coleenp@2497 124
duke@435 125 // Lookup a symbol in a bucket.
duke@435 126
coleenp@2497 127 Symbol* SymbolTable::lookup(int index, const char* name,
duke@435 128 int len, unsigned int hash) {
coleenp@2497 129 for (HashtableEntry<Symbol*>* e = bucket(index); e != NULL; e = e->next()) {
duke@435 130 if (e->hash() == hash) {
coleenp@2497 131 Symbol* sym = e->literal();
duke@435 132 if (sym->equals(name, len)) {
coleenp@2497 133 // something is referencing this symbol now.
coleenp@2497 134 sym->increment_refcount();
duke@435 135 return sym;
duke@435 136 }
duke@435 137 }
duke@435 138 }
duke@435 139 return NULL;
duke@435 140 }
duke@435 141
duke@435 142
duke@435 143 // We take care not to be blocking while holding the
duke@435 144 // SymbolTable_lock. Otherwise, the system might deadlock, since the
duke@435 145 // symboltable is used during compilation (VM_thread) The lock free
duke@435 146 // synchronization is simplified by the fact that we do not delete
duke@435 147 // entries in the symbol table during normal execution (only during
duke@435 148 // safepoints).
duke@435 149
coleenp@2497 150 Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) {
duke@435 151 unsigned int hashValue = hash_symbol(name, len);
duke@435 152 int index = the_table()->hash_to_index(hashValue);
duke@435 153
coleenp@2497 154 Symbol* s = the_table()->lookup(index, name, len, hashValue);
duke@435 155
duke@435 156 // Found
duke@435 157 if (s != NULL) return s;
duke@435 158
duke@435 159 // Otherwise, add to symbol to table
coleenp@3682 160 return the_table()->basic_add(index, (u1*)name, len, hashValue, true, CHECK_NULL);
duke@435 161 }
duke@435 162
coleenp@2497 163 Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
duke@435 164 char* buffer;
duke@435 165 int index, len;
duke@435 166 unsigned int hashValue;
duke@435 167 char* name;
duke@435 168 {
duke@435 169 debug_only(No_Safepoint_Verifier nsv;)
duke@435 170
duke@435 171 name = (char*)sym->base() + begin;
duke@435 172 len = end - begin;
duke@435 173 hashValue = hash_symbol(name, len);
duke@435 174 index = the_table()->hash_to_index(hashValue);
coleenp@2497 175 Symbol* s = the_table()->lookup(index, name, len, hashValue);
duke@435 176
duke@435 177 // Found
duke@435 178 if (s != NULL) return s;
duke@435 179 }
duke@435 180
duke@435 181 // Otherwise, add to symbol to table. Copy to a C string first.
duke@435 182 char stack_buf[128];
duke@435 183 ResourceMark rm(THREAD);
duke@435 184 if (len <= 128) {
duke@435 185 buffer = stack_buf;
duke@435 186 } else {
duke@435 187 buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
duke@435 188 }
duke@435 189 for (int i=0; i<len; i++) {
duke@435 190 buffer[i] = name[i];
duke@435 191 }
duke@435 192 // Make sure there is no safepoint in the code above since name can't move.
duke@435 193 // We can't include the code in No_Safepoint_Verifier because of the
duke@435 194 // ResourceMark.
duke@435 195
coleenp@3682 196 return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, CHECK_NULL);
duke@435 197 }
duke@435 198
coleenp@2497 199 Symbol* SymbolTable::lookup_only(const char* name, int len,
duke@435 200 unsigned int& hash) {
duke@435 201 hash = hash_symbol(name, len);
duke@435 202 int index = the_table()->hash_to_index(hash);
duke@435 203
coleenp@2497 204 Symbol* s = the_table()->lookup(index, name, len, hash);
coleenp@2497 205 return s;
duke@435 206 }
duke@435 207
phh@3427 208 // Look up the address of the literal in the SymbolTable for this Symbol*
phh@3427 209 // Do not create any new symbols
phh@3427 210 // Do not increment the reference count to keep this alive
phh@3427 211 Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){
phh@3427 212 unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length());
phh@3427 213 int index = the_table()->hash_to_index(hash);
phh@3427 214
phh@3427 215 for (HashtableEntry<Symbol*>* e = the_table()->bucket(index); e != NULL; e = e->next()) {
phh@3427 216 if (e->hash() == hash) {
phh@3427 217 Symbol* literal_sym = e->literal();
phh@3427 218 if (sym == literal_sym) {
phh@3427 219 return e->literal_addr();
phh@3427 220 }
phh@3427 221 }
phh@3427 222 }
phh@3427 223 return NULL;
phh@3427 224 }
phh@3427 225
jrose@1100 226 // Suggestion: Push unicode-based lookup all the way into the hashing
jrose@1100 227 // and probing logic, so there is no need for convert_to_utf8 until
coleenp@2497 228 // an actual new Symbol* is created.
coleenp@2497 229 Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) {
jrose@1100 230 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
jrose@1100 231 char stack_buf[128];
jrose@1100 232 if (utf8_length < (int) sizeof(stack_buf)) {
jrose@1100 233 char* chars = stack_buf;
jrose@1100 234 UNICODE::convert_to_utf8(name, utf16_length, chars);
jrose@1100 235 return lookup(chars, utf8_length, THREAD);
jrose@1100 236 } else {
jrose@1100 237 ResourceMark rm(THREAD);
jrose@1100 238 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
jrose@1100 239 UNICODE::convert_to_utf8(name, utf16_length, chars);
jrose@1100 240 return lookup(chars, utf8_length, THREAD);
jrose@1100 241 }
jrose@1100 242 }
jrose@1100 243
coleenp@2497 244 Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length,
jrose@1100 245 unsigned int& hash) {
jrose@1100 246 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
jrose@1100 247 char stack_buf[128];
jrose@1100 248 if (utf8_length < (int) sizeof(stack_buf)) {
jrose@1100 249 char* chars = stack_buf;
jrose@1100 250 UNICODE::convert_to_utf8(name, utf16_length, chars);
jrose@1100 251 return lookup_only(chars, utf8_length, hash);
jrose@1100 252 } else {
jrose@1100 253 ResourceMark rm;
jrose@1100 254 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
jrose@1100 255 UNICODE::convert_to_utf8(name, utf16_length, chars);
jrose@1100 256 return lookup_only(chars, utf8_length, hash);
jrose@1100 257 }
jrose@1100 258 }
jrose@1100 259
coleenp@3682 260 void SymbolTable::add(Handle class_loader, constantPoolHandle cp,
coleenp@3682 261 int names_count,
duke@435 262 const char** names, int* lengths, int* cp_indices,
duke@435 263 unsigned int* hashValues, TRAPS) {
duke@435 264 SymbolTable* table = the_table();
coleenp@3682 265 bool added = table->basic_add(class_loader, cp, names_count, names, lengths,
duke@435 266 cp_indices, hashValues, CHECK);
duke@435 267 if (!added) {
duke@435 268 // do it the hard way
duke@435 269 for (int i=0; i<names_count; i++) {
duke@435 270 int index = table->hash_to_index(hashValues[i]);
coleenp@3682 271 bool c_heap = class_loader() != NULL;
coleenp@3682 272 Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK);
duke@435 273 cp->symbol_at_put(cp_indices[i], sym);
duke@435 274 }
duke@435 275 }
duke@435 276 }
duke@435 277
coleenp@3682 278 Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) {
coleenp@3682 279 unsigned int hash;
coleenp@3682 280 Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash);
coleenp@3682 281 if (result != NULL) {
coleenp@3682 282 return result;
coleenp@3682 283 }
coleenp@3682 284 SymbolTable* table = the_table();
coleenp@3682 285 int index = table->hash_to_index(hash);
coleenp@3682 286 return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD);
coleenp@3682 287 }
coleenp@3682 288
coleenp@2497 289 Symbol* SymbolTable::basic_add(int index, u1 *name, int len,
coleenp@3682 290 unsigned int hashValue, bool c_heap, TRAPS) {
duke@435 291 assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
duke@435 292 "proposed name of symbol must be stable");
duke@435 293
coleenp@3682 294 // Grab SymbolTable_lock first.
duke@435 295 MutexLocker ml(SymbolTable_lock, THREAD);
duke@435 296
duke@435 297 // Since look-up was done lock-free, we need to check if another
duke@435 298 // thread beat us in the race to insert the symbol.
coleenp@2497 299 Symbol* test = lookup(index, (char*)name, len, hashValue);
duke@435 300 if (test != NULL) {
coleenp@3682 301 // A race occurred and another thread introduced the symbol.
coleenp@2497 302 assert(test->refcount() != 0, "lookup should have incremented the count");
duke@435 303 return test;
duke@435 304 }
duke@435 305
coleenp@3682 306 // Create a new symbol.
coleenp@3682 307 Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL);
coleenp@3682 308 assert(sym->equals((char*)name, len), "symbol must be properly initialized");
coleenp@3682 309
coleenp@2497 310 HashtableEntry<Symbol*>* entry = new_entry(hashValue, sym);
duke@435 311 add_entry(index, entry);
coleenp@2497 312 return sym;
duke@435 313 }
duke@435 314
coleenp@3682 315 // This version of basic_add adds symbols in batch from the constant pool
coleenp@3682 316 // parsing.
coleenp@3682 317 bool SymbolTable::basic_add(Handle class_loader, constantPoolHandle cp,
coleenp@3682 318 int names_count,
duke@435 319 const char** names, int* lengths,
duke@435 320 int* cp_indices, unsigned int* hashValues,
duke@435 321 TRAPS) {
coleenp@3682 322
coleenp@3682 323 // Check symbol names are not too long. If any are too long, don't add any.
coleenp@3682 324 for (int i = 0; i< names_count; i++) {
coleenp@3682 325 if (lengths[i] > Symbol::max_length()) {
coleenp@3682 326 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
coleenp@3682 327 "name is too long to represent");
coleenp@3682 328 }
duke@435 329 }
duke@435 330
coleenp@3682 331 // Hold SymbolTable_lock through the symbol creation
duke@435 332 MutexLocker ml(SymbolTable_lock, THREAD);
duke@435 333
coleenp@2497 334 for (int i=0; i<names_count; i++) {
duke@435 335 // Since look-up was done lock-free, we need to check if another
duke@435 336 // thread beat us in the race to insert the symbol.
duke@435 337 int index = hash_to_index(hashValues[i]);
coleenp@2497 338 Symbol* test = lookup(index, names[i], lengths[i], hashValues[i]);
duke@435 339 if (test != NULL) {
twisti@1040 340 // A race occurred and another thread introduced the symbol, this one
duke@435 341 // will be dropped and collected. Use test instead.
duke@435 342 cp->symbol_at_put(cp_indices[i], test);
coleenp@2497 343 assert(test->refcount() != 0, "lookup should have incremented the count");
duke@435 344 } else {
coleenp@3682 345 // Create a new symbol. The null class loader is never unloaded so these
coleenp@3682 346 // are allocated specially in a permanent arena.
coleenp@3682 347 bool c_heap = class_loader() != NULL;
coleenp@3682 348 Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false));
coleenp@3682 349 assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized"); // why wouldn't it be???
coleenp@2497 350 HashtableEntry<Symbol*>* entry = new_entry(hashValues[i], sym);
duke@435 351 add_entry(index, entry);
duke@435 352 cp->symbol_at_put(cp_indices[i], sym);
duke@435 353 }
duke@435 354 }
duke@435 355 return true;
duke@435 356 }
duke@435 357
duke@435 358
duke@435 359 void SymbolTable::verify() {
duke@435 360 for (int i = 0; i < the_table()->table_size(); ++i) {
coleenp@2497 361 HashtableEntry<Symbol*>* p = the_table()->bucket(i);
duke@435 362 for ( ; p != NULL; p = p->next()) {
coleenp@2497 363 Symbol* s = (Symbol*)(p->literal());
duke@435 364 guarantee(s != NULL, "symbol is NULL");
duke@435 365 unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
duke@435 366 guarantee(p->hash() == h, "broken hash in symbol table entry");
duke@435 367 guarantee(the_table()->hash_to_index(h) == i,
duke@435 368 "wrong index in symbol table");
duke@435 369 }
duke@435 370 }
duke@435 371 }
duke@435 372
duke@435 373
duke@435 374 //---------------------------------------------------------------------------
duke@435 375 // Non-product code
duke@435 376
duke@435 377 #ifndef PRODUCT
duke@435 378
duke@435 379 void SymbolTable::print_histogram() {
duke@435 380 MutexLocker ml(SymbolTable_lock);
duke@435 381 const int results_length = 100;
duke@435 382 int results[results_length];
duke@435 383 int i,j;
duke@435 384
duke@435 385 // initialize results to zero
duke@435 386 for (j = 0; j < results_length; j++) {
duke@435 387 results[j] = 0;
duke@435 388 }
duke@435 389
duke@435 390 int total = 0;
duke@435 391 int max_symbols = 0;
duke@435 392 int out_of_range = 0;
coleenp@2497 393 int memory_total = 0;
coleenp@2497 394 int count = 0;
duke@435 395 for (i = 0; i < the_table()->table_size(); i++) {
coleenp@2497 396 HashtableEntry<Symbol*>* p = the_table()->bucket(i);
duke@435 397 for ( ; p != NULL; p = p->next()) {
coleenp@2497 398 memory_total += p->literal()->object_size();
coleenp@2497 399 count++;
coleenp@2497 400 int counter = p->literal()->utf8_length();
duke@435 401 total += counter;
duke@435 402 if (counter < results_length) {
duke@435 403 results[counter]++;
duke@435 404 } else {
duke@435 405 out_of_range++;
duke@435 406 }
duke@435 407 max_symbols = MAX2(max_symbols, counter);
duke@435 408 }
duke@435 409 }
duke@435 410 tty->print_cr("Symbol Table:");
coleenp@2497 411 tty->print_cr("Total number of symbols %5d", count);
coleenp@2497 412 tty->print_cr("Total size in memory %5dK",
coleenp@2497 413 (memory_total*HeapWordSize)/1024);
coleenp@2497 414 tty->print_cr("Total counted %5d", symbols_counted);
coleenp@2497 415 tty->print_cr("Total removed %5d", symbols_removed);
coleenp@2497 416 if (symbols_counted > 0) {
coleenp@2497 417 tty->print_cr("Percent removed %3.2f",
coleenp@2497 418 ((float)symbols_removed/(float)symbols_counted)* 100);
coleenp@2497 419 }
coleenp@2497 420 tty->print_cr("Reference counts %5d", Symbol::_total_count);
coleenp@3682 421 tty->print_cr("Symbol arena size %5d used %5d",
coleenp@3682 422 arena()->size_in_bytes(), arena()->used());
coleenp@2497 423 tty->print_cr("Histogram of symbol length:");
duke@435 424 tty->print_cr("%8s %5d", "Total ", total);
duke@435 425 tty->print_cr("%8s %5d", "Maximum", max_symbols);
duke@435 426 tty->print_cr("%8s %3.2f", "Average",
duke@435 427 ((float) total / (float) the_table()->table_size()));
duke@435 428 tty->print_cr("%s", "Histogram:");
duke@435 429 tty->print_cr(" %s %29s", "Length", "Number chains that length");
duke@435 430 for (i = 0; i < results_length; i++) {
duke@435 431 if (results[i] > 0) {
duke@435 432 tty->print_cr("%6d %10d", i, results[i]);
duke@435 433 }
duke@435 434 }
coleenp@2497 435 if (Verbose) {
coleenp@2497 436 int line_length = 70;
coleenp@2497 437 tty->print_cr("%s %30s", " Length", "Number chains that length");
coleenp@2497 438 for (i = 0; i < results_length; i++) {
coleenp@2497 439 if (results[i] > 0) {
coleenp@2497 440 tty->print("%4d", i);
coleenp@2497 441 for (j = 0; (j < results[i]) && (j < line_length); j++) {
coleenp@2497 442 tty->print("%1s", "*");
coleenp@2497 443 }
coleenp@2497 444 if (j == line_length) {
coleenp@2497 445 tty->print("%1s", "+");
coleenp@2497 446 }
coleenp@2497 447 tty->cr();
duke@435 448 }
coleenp@2497 449 }
coleenp@2497 450 }
coleenp@2497 451 tty->print_cr(" %s %d: %d\n", "Number chains longer than",
coleenp@2497 452 results_length, out_of_range);
coleenp@2497 453 }
coleenp@2497 454
coleenp@2497 455 void SymbolTable::print() {
coleenp@2497 456 for (int i = 0; i < the_table()->table_size(); ++i) {
coleenp@2497 457 HashtableEntry<Symbol*>** p = the_table()->bucket_addr(i);
coleenp@2497 458 HashtableEntry<Symbol*>* entry = the_table()->bucket(i);
coleenp@2497 459 if (entry != NULL) {
coleenp@2497 460 while (entry != NULL) {
coleenp@2497 461 tty->print(PTR_FORMAT " ", entry->literal());
coleenp@2497 462 entry->literal()->print();
coleenp@2497 463 tty->print(" %d", entry->literal()->refcount());
coleenp@2497 464 p = entry->next_addr();
coleenp@2497 465 entry = (HashtableEntry<Symbol*>*)HashtableEntry<Symbol*>::make_ptr(*p);
duke@435 466 }
duke@435 467 tty->cr();
duke@435 468 }
duke@435 469 }
duke@435 470 }
duke@435 471
duke@435 472 #endif // PRODUCT
duke@435 473
duke@435 474 // --------------------------------------------------------------------------
duke@435 475
duke@435 476 #ifdef ASSERT
duke@435 477 class StableMemoryChecker : public StackObj {
duke@435 478 enum { _bufsize = wordSize*4 };
duke@435 479
duke@435 480 address _region;
duke@435 481 jint _size;
duke@435 482 u1 _save_buf[_bufsize];
duke@435 483
duke@435 484 int sample(u1* save_buf) {
duke@435 485 if (_size <= _bufsize) {
duke@435 486 memcpy(save_buf, _region, _size);
duke@435 487 return _size;
duke@435 488 } else {
duke@435 489 // copy head and tail
duke@435 490 memcpy(&save_buf[0], _region, _bufsize/2);
duke@435 491 memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
duke@435 492 return (_bufsize/2)*2;
duke@435 493 }
duke@435 494 }
duke@435 495
duke@435 496 public:
duke@435 497 StableMemoryChecker(const void* region, jint size) {
duke@435 498 _region = (address) region;
duke@435 499 _size = size;
duke@435 500 sample(_save_buf);
duke@435 501 }
duke@435 502
duke@435 503 bool verify() {
duke@435 504 u1 check_buf[sizeof(_save_buf)];
duke@435 505 int check_size = sample(check_buf);
duke@435 506 return (0 == memcmp(_save_buf, check_buf, check_size));
duke@435 507 }
duke@435 508
duke@435 509 void set_region(const void* region) { _region = (address) region; }
duke@435 510 };
duke@435 511 #endif
duke@435 512
duke@435 513
duke@435 514 // --------------------------------------------------------------------------
duke@435 515 StringTable* StringTable::_the_table = NULL;
duke@435 516
duke@435 517 oop StringTable::lookup(int index, jchar* name,
duke@435 518 int len, unsigned int hash) {
coleenp@2497 519 for (HashtableEntry<oop>* l = bucket(index); l != NULL; l = l->next()) {
duke@435 520 if (l->hash() == hash) {
duke@435 521 if (java_lang_String::equals(l->literal(), name, len)) {
duke@435 522 return l->literal();
duke@435 523 }
duke@435 524 }
duke@435 525 }
duke@435 526 return NULL;
duke@435 527 }
duke@435 528
duke@435 529
duke@435 530 oop StringTable::basic_add(int index, Handle string_or_null, jchar* name,
duke@435 531 int len, unsigned int hashValue, TRAPS) {
duke@435 532 debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
duke@435 533 assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
duke@435 534 "proposed name of symbol must be stable");
duke@435 535
duke@435 536 Handle string;
duke@435 537 // try to reuse the string if possible
jcoomes@2661 538 if (!string_or_null.is_null() && (!JavaObjectsInPerm || string_or_null()->is_perm())) {
duke@435 539 string = string_or_null;
duke@435 540 } else {
duke@435 541 string = java_lang_String::create_tenured_from_unicode(name, len, CHECK_NULL);
duke@435 542 }
duke@435 543
duke@435 544 // Allocation must be done before grapping the SymbolTable_lock lock
duke@435 545 MutexLocker ml(StringTable_lock, THREAD);
duke@435 546
duke@435 547 assert(java_lang_String::equals(string(), name, len),
duke@435 548 "string must be properly initialized");
duke@435 549
duke@435 550 // Since look-up was done lock-free, we need to check if another
duke@435 551 // thread beat us in the race to insert the symbol.
duke@435 552
duke@435 553 oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int)
duke@435 554 if (test != NULL) {
duke@435 555 // Entry already added
duke@435 556 return test;
duke@435 557 }
duke@435 558
coleenp@2497 559 HashtableEntry<oop>* entry = new_entry(hashValue, string());
duke@435 560 add_entry(index, entry);
duke@435 561 return string();
duke@435 562 }
duke@435 563
duke@435 564
coleenp@2497 565 oop StringTable::lookup(Symbol* symbol) {
duke@435 566 ResourceMark rm;
duke@435 567 int length;
duke@435 568 jchar* chars = symbol->as_unicode(length);
never@2700 569 unsigned int hashValue = java_lang_String::hash_string(chars, length);
duke@435 570 int index = the_table()->hash_to_index(hashValue);
duke@435 571 return the_table()->lookup(index, chars, length, hashValue);
duke@435 572 }
duke@435 573
duke@435 574
duke@435 575 oop StringTable::intern(Handle string_or_null, jchar* name,
duke@435 576 int len, TRAPS) {
never@2700 577 unsigned int hashValue = java_lang_String::hash_string(name, len);
duke@435 578 int index = the_table()->hash_to_index(hashValue);
duke@435 579 oop string = the_table()->lookup(index, name, len, hashValue);
duke@435 580
duke@435 581 // Found
duke@435 582 if (string != NULL) return string;
duke@435 583
duke@435 584 // Otherwise, add to symbol to table
duke@435 585 return the_table()->basic_add(index, string_or_null, name, len,
duke@435 586 hashValue, CHECK_NULL);
duke@435 587 }
duke@435 588
coleenp@2497 589 oop StringTable::intern(Symbol* symbol, TRAPS) {
duke@435 590 if (symbol == NULL) return NULL;
duke@435 591 ResourceMark rm(THREAD);
duke@435 592 int length;
duke@435 593 jchar* chars = symbol->as_unicode(length);
duke@435 594 Handle string;
duke@435 595 oop result = intern(string, chars, length, CHECK_NULL);
duke@435 596 return result;
duke@435 597 }
duke@435 598
duke@435 599
duke@435 600 oop StringTable::intern(oop string, TRAPS)
duke@435 601 {
duke@435 602 if (string == NULL) return NULL;
duke@435 603 ResourceMark rm(THREAD);
duke@435 604 int length;
duke@435 605 Handle h_string (THREAD, string);
duke@435 606 jchar* chars = java_lang_String::as_unicode_string(string, length);
duke@435 607 oop result = intern(h_string, chars, length, CHECK_NULL);
duke@435 608 return result;
duke@435 609 }
duke@435 610
duke@435 611
duke@435 612 oop StringTable::intern(const char* utf8_string, TRAPS) {
duke@435 613 if (utf8_string == NULL) return NULL;
duke@435 614 ResourceMark rm(THREAD);
duke@435 615 int length = UTF8::unicode_length(utf8_string);
duke@435 616 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
duke@435 617 UTF8::convert_to_unicode(utf8_string, chars, length);
duke@435 618 Handle string;
duke@435 619 oop result = intern(string, chars, length, CHECK_NULL);
duke@435 620 return result;
duke@435 621 }
duke@435 622
coleenp@2497 623 void StringTable::unlink(BoolObjectClosure* is_alive) {
coleenp@2497 624 // Readers of the table are unlocked, so we should only be removing
coleenp@2497 625 // entries at a safepoint.
coleenp@2497 626 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
coleenp@2497 627 for (int i = 0; i < the_table()->table_size(); ++i) {
coleenp@2497 628 for (HashtableEntry<oop>** p = the_table()->bucket_addr(i); *p != NULL; ) {
coleenp@2497 629 HashtableEntry<oop>* entry = *p;
coleenp@2497 630 if (entry->is_shared()) {
coleenp@2497 631 break;
coleenp@2497 632 }
coleenp@2497 633 assert(entry->literal() != NULL, "just checking");
coleenp@2497 634 if (is_alive->do_object_b(entry->literal())) {
coleenp@2497 635 p = entry->next_addr();
coleenp@2497 636 } else {
coleenp@2497 637 *p = entry->next();
coleenp@2497 638 the_table()->free_entry(entry);
coleenp@2497 639 }
coleenp@2497 640 }
coleenp@2497 641 }
coleenp@2497 642 }
coleenp@2497 643
coleenp@2497 644 void StringTable::oops_do(OopClosure* f) {
coleenp@2497 645 for (int i = 0; i < the_table()->table_size(); ++i) {
coleenp@2497 646 HashtableEntry<oop>** p = the_table()->bucket_addr(i);
coleenp@2497 647 HashtableEntry<oop>* entry = the_table()->bucket(i);
coleenp@2497 648 while (entry != NULL) {
coleenp@2497 649 f->do_oop((oop*)entry->literal_addr());
coleenp@2497 650
coleenp@2497 651 // Did the closure remove the literal from the table?
coleenp@2497 652 if (entry->literal() == NULL) {
coleenp@2497 653 assert(!entry->is_shared(), "immutable hashtable entry?");
coleenp@2497 654 *p = entry->next();
coleenp@2497 655 the_table()->free_entry(entry);
coleenp@2497 656 } else {
coleenp@2497 657 p = entry->next_addr();
coleenp@2497 658 }
coleenp@2497 659 entry = (HashtableEntry<oop>*)HashtableEntry<oop>::make_ptr(*p);
coleenp@2497 660 }
coleenp@2497 661 }
coleenp@2497 662 }
coleenp@2497 663
duke@435 664 void StringTable::verify() {
duke@435 665 for (int i = 0; i < the_table()->table_size(); ++i) {
coleenp@2497 666 HashtableEntry<oop>* p = the_table()->bucket(i);
duke@435 667 for ( ; p != NULL; p = p->next()) {
duke@435 668 oop s = p->literal();
duke@435 669 guarantee(s != NULL, "interned string is NULL");
jcoomes@2661 670 guarantee(s->is_perm() || !JavaObjectsInPerm, "interned string not in permspace");
never@2700 671 unsigned int h = java_lang_String::hash_string(s);
duke@435 672 guarantee(p->hash() == h, "broken hash in string table entry");
duke@435 673 guarantee(the_table()->hash_to_index(h) == i,
duke@435 674 "wrong index in string table");
duke@435 675 }
duke@435 676 }
duke@435 677 }

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