rev 48017 : [mq]: Access_strings

   1 /*
   2  * Copyright (c) 1997, 2017, 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.inline.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 "logging/log.hpp"
  34 #include "memory/allocation.inline.hpp"
  35 #include "memory/filemap.hpp"
  36 #include "memory/metaspaceShared.hpp"
  37 #include "memory/resourceArea.hpp"

  38 #include "oops/oop.inline.hpp"
  39 #include "runtime/atomic.hpp"
  40 #include "runtime/mutexLocker.hpp"
  41 #include "services/diagnosticCommand.hpp"
  42 #include "utilities/hashtable.inline.hpp"
  43 #include "utilities/macros.hpp"
  44 #if INCLUDE_ALL_GCS
  45 #include "gc/g1/g1CollectedHeap.hpp"
  46 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  47 #include "gc/g1/g1StringDedup.hpp"
  48 #endif
  49 
  50 // the number of buckets a thread claims
  51 const int ClaimChunkSize = 32;
  52 
  53 #ifdef ASSERT
  54 class StableMemoryChecker : public StackObj {
  55   enum { _bufsize = wordSize*4 };
  56 
  57   address _region;
  58   jint    _size;
  59   u1      _save_buf[_bufsize];
  60 
  61   int sample(u1* save_buf) {
  62     if (_size <= _bufsize) {
  63       memcpy(save_buf, _region, _size);
  64       return _size;
  65     } else {
  66       // copy head and tail
  67       memcpy(&save_buf[0],          _region,                      _bufsize/2);
  68       memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
  69       return (_bufsize/2)*2;
  70     }
  71   }
  72 
  73  public:
  74   StableMemoryChecker(const void* region, jint size) {
  75     _region = (address) region;
  76     _size   = size;
  77     sample(_save_buf);
  78   }
  79 
  80   bool verify() {
  81     u1 check_buf[sizeof(_save_buf)];
  82     int check_size = sample(check_buf);
  83     return (0 == memcmp(_save_buf, check_buf, check_size));
  84   }
  85 
  86   void set_region(const void* region) { _region = (address) region; }
  87 };
  88 #endif
  89 
  90 
  91 // --------------------------------------------------------------------------
  92 StringTable* StringTable::_the_table = NULL;
  93 bool StringTable::_shared_string_mapped = false;
  94 bool StringTable::_needs_rehashing = false;
  95 
  96 volatile int StringTable::_parallel_claimed_idx = 0;
  97 
  98 CompactHashtable<oop, char> StringTable::_shared_table;
  99 
 100 // Pick hashing algorithm
 101 unsigned int StringTable::hash_string(const jchar* s, int len) {
 102   return use_alternate_hashcode() ? alt_hash_string(s, len) :
 103                                     java_lang_String::hash_code(s, len);
 104 }
 105 
 106 unsigned int StringTable::alt_hash_string(const jchar* s, int len) {
 107   return AltHashing::murmur3_32(seed(), s, len);
 108 }
 109 
 110 unsigned int StringTable::hash_string(oop string) {
 111   EXCEPTION_MARK;
 112   if (string == NULL) {
 113     return hash_string((jchar*)NULL, 0);
 114   }
 115   ResourceMark rm(THREAD);
 116   // All String oops are hashed as unicode
 117   int length;
 118   jchar* chars = java_lang_String::as_unicode_string(string, length, THREAD);
 119   if (chars != NULL) {
 120     return hash_string(chars, length);
 121   } else {
 122     vm_exit_out_of_memory(length, OOM_MALLOC_ERROR, "unable to create Unicode string for verification");
 123     return 0;
 124   }
 125 }
 126 
















 127 oop StringTable::lookup_shared(jchar* name, int len, unsigned int hash) {
 128   assert(hash == java_lang_String::hash_code(name, len),
 129          "hash must be computed using java_lang_String::hash_code");
 130   return _shared_table.lookup((const char*)name, hash, len);
 131 }
 132 
 133 oop StringTable::lookup_in_main_table(int index, jchar* name,
 134                                 int len, unsigned int hash) {
 135   int count = 0;
 136   for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) {
 137     count++;
 138     if (l->hash() == hash) {
 139       if (java_lang_String::equals(l->literal(), name, len)) {
 140         return l->literal();

 141       }
 142     }
 143   }
 144   // If the bucket size is too deep check if this hash code is insufficient.
 145   if (count >= rehash_count && !needs_rehashing()) {
 146     _needs_rehashing = check_rehash_table(count);
 147   }
 148   return NULL;
 149 }
 150 
 151 
 152 oop StringTable::basic_add(int index_arg, Handle string, jchar* name,
 153                            int len, unsigned int hashValue_arg, TRAPS) {
 154 
 155   assert(java_lang_String::equals(string(), name, len),
 156          "string must be properly initialized");
 157   // Cannot hit a safepoint in this function because the "this" pointer can move.
 158   NoSafepointVerifier nsv;
 159 
 160   // Check if the symbol table has been rehashed, if so, need to recalculate
 161   // the hash value and index before second lookup.
 162   unsigned int hashValue;
 163   int index;
 164   if (use_alternate_hashcode()) {
 165     hashValue = alt_hash_string(name, len);
 166     index = hash_to_index(hashValue);
 167   } else {
 168     hashValue = hashValue_arg;
 169     index = index_arg;
 170   }
 171 
 172   // Since look-up was done lock-free, we need to check if another
 173   // thread beat us in the race to insert the symbol.
 174 
 175   // No need to lookup the shared table from here since the caller (intern()) already did
 176   oop test = lookup_in_main_table(index, name, len, hashValue); // calls lookup(u1*, int)
 177   if (test != NULL) {
 178     // Entry already added
 179     return test;
 180   }
 181 
 182   HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string());
 183   add_entry(index, entry);
 184   return string();
 185 }
 186 
 187 
 188 oop StringTable::lookup(Symbol* symbol) {
 189   ResourceMark rm;
 190   int length;
 191   jchar* chars = symbol->as_unicode(length);
 192   return lookup(chars, length);
 193 }
 194 
 195 // Tell the GC that this string was looked up in the StringTable.
 196 static void ensure_string_alive(oop string) {
 197   // A lookup in the StringTable could return an object that was previously
 198   // considered dead. The SATB part of G1 needs to get notified about this
 199   // potential resurrection, otherwise the marking might not find the object.
 200 #if INCLUDE_ALL_GCS
 201   if (UseG1GC && string != NULL) {
 202     G1SATBCardTableModRefBS::enqueue(string);
 203   }
 204 #endif
 205 }
 206 
 207 oop StringTable::lookup(jchar* name, int len) {
 208   // shared table always uses java_lang_String::hash_code
 209   unsigned int hash = java_lang_String::hash_code(name, len);
 210   oop string = lookup_shared(name, len, hash);
 211   if (string != NULL) {
 212     return string;
 213   }
 214   if (use_alternate_hashcode()) {
 215     hash = alt_hash_string(name, len);
 216   }
 217   int index = the_table()->hash_to_index(hash);
 218   string = the_table()->lookup_in_main_table(index, name, len, hash);
 219 
 220   ensure_string_alive(string);
 221 
 222   return string;
 223 }
 224 
 225 oop StringTable::intern(Handle string_or_null, jchar* name,
 226                         int len, TRAPS) {
 227   // shared table always uses java_lang_String::hash_code
 228   unsigned int hashValue = java_lang_String::hash_code(name, len);
 229   oop found_string = lookup_shared(name, len, hashValue);
 230   if (found_string != NULL) {
 231     return found_string;
 232   }
 233   if (use_alternate_hashcode()) {
 234     hashValue = alt_hash_string(name, len);
 235   }
 236   int index = the_table()->hash_to_index(hashValue);
 237   found_string = the_table()->lookup_in_main_table(index, name, len, hashValue);
 238 
 239   // Found
 240   if (found_string != NULL) {
 241     if (found_string != string_or_null()) {
 242       ensure_string_alive(found_string);
 243     }
 244     return found_string;
 245   }
 246 
 247   debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
 248   assert(!Universe::heap()->is_in_reserved(name),
 249          "proposed name of symbol must be stable");
 250 
 251   HandleMark hm(THREAD);  // cleanup strings created
 252   Handle string;
 253   // try to reuse the string if possible
 254   if (!string_or_null.is_null()) {
 255     string = string_or_null;
 256   } else {
 257     string = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
 258   }
 259 
 260 #if INCLUDE_ALL_GCS
 261   if (G1StringDedup::is_enabled()) {
 262     // Deduplicate the string before it is interned. Note that we should never
 263     // deduplicate a string after it has been interned. Doing so will counteract
 264     // compiler optimizations done on e.g. interned string literals.
 265     G1StringDedup::deduplicate(string());
 266   }
 267 #endif
 268 
 269   // Grab the StringTable_lock before getting the_table() because it could
 270   // change at safepoint.
 271   oop added_or_found;
 272   {
 273     MutexLocker ml(StringTable_lock, THREAD);
 274     // Otherwise, add to symbol to table
 275     added_or_found = the_table()->basic_add(index, string, name, len,
 276                                   hashValue, CHECK_NULL);
 277   }
 278 
 279   if (added_or_found != string()) {
 280     ensure_string_alive(added_or_found);
 281   }
 282 
 283   return added_or_found;
 284 }
 285 
 286 oop StringTable::intern(Symbol* symbol, TRAPS) {
 287   if (symbol == NULL) return NULL;
 288   ResourceMark rm(THREAD);
 289   int length;
 290   jchar* chars = symbol->as_unicode(length);
 291   Handle string;
 292   oop result = intern(string, chars, length, CHECK_NULL);
 293   return result;
 294 }
 295 
 296 
 297 oop StringTable::intern(oop string, TRAPS)
 298 {
 299   if (string == NULL) return NULL;
 300   ResourceMark rm(THREAD);
 301   int length;
 302   Handle h_string (THREAD, string);
 303   jchar* chars = java_lang_String::as_unicode_string(string, length, CHECK_NULL);
 304   oop result = intern(h_string, chars, length, CHECK_NULL);
 305   return result;
 306 }
 307 
 308 
 309 oop StringTable::intern(const char* utf8_string, TRAPS) {
 310   if (utf8_string == NULL) return NULL;
 311   ResourceMark rm(THREAD);
 312   int length = UTF8::unicode_length(utf8_string);
 313   jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
 314   UTF8::convert_to_unicode(utf8_string, chars, length);
 315   Handle string;
 316   oop result = intern(string, chars, length, CHECK_NULL);
 317   return result;
 318 }
 319 
 320 void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
 321   BucketUnlinkContext context;
 322   buckets_unlink_or_oops_do(is_alive, f, 0, the_table()->table_size(), &context);
 323   _the_table->bulk_free_entries(&context);
 324   *processed = context._num_processed;
 325   *removed = context._num_removed;
 326 }
 327 
 328 void StringTable::possibly_parallel_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
 329   // Readers of the table are unlocked, so we should only be removing
 330   // entries at a safepoint.
 331   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 332   const int limit = the_table()->table_size();
 333 
 334   BucketUnlinkContext context;
 335   for (;;) {
 336     // Grab next set of buckets to scan
 337     int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
 338     if (start_idx >= limit) {
 339       // End of table
 340       break;
 341     }
 342 
 343     int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
 344     buckets_unlink_or_oops_do(is_alive, f, start_idx, end_idx, &context);
 345   }
 346   _the_table->bulk_free_entries(&context);
 347   *processed = context._num_processed;
 348   *removed = context._num_removed;
 349 }
 350 
 351 void StringTable::buckets_oops_do(OopClosure* f, int start_idx, int end_idx) {
 352   const int limit = the_table()->table_size();
 353 
 354   assert(0 <= start_idx && start_idx <= limit,
 355          "start_idx (%d) is out of bounds", start_idx);
 356   assert(0 <= end_idx && end_idx <= limit,
 357          "end_idx (%d) is out of bounds", end_idx);
 358   assert(start_idx <= end_idx,
 359          "Index ordering: start_idx=%d, end_idx=%d",
 360          start_idx, end_idx);
 361 
 362   for (int i = start_idx; i < end_idx; i += 1) {
 363     HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
 364     while (entry != NULL) {
 365       assert(!entry->is_shared(), "CDS not used for the StringTable");
 366 
 367       f->do_oop((oop*)entry->literal_addr());
 368 
 369       entry = entry->next();
 370     }
 371   }
 372 }
 373 
 374 void StringTable::buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, BucketUnlinkContext* context) {
 375   const int limit = the_table()->table_size();
 376 
 377   assert(0 <= start_idx && start_idx <= limit,
 378          "start_idx (%d) is out of bounds", start_idx);
 379   assert(0 <= end_idx && end_idx <= limit,
 380          "end_idx (%d) is out of bounds", end_idx);
 381   assert(start_idx <= end_idx,
 382          "Index ordering: start_idx=%d, end_idx=%d",
 383          start_idx, end_idx);
 384 
 385   for (int i = start_idx; i < end_idx; ++i) {
 386     HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i);
 387     HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
 388     while (entry != NULL) {
 389       assert(!entry->is_shared(), "CDS not used for the StringTable");
 390 
 391       if (is_alive->do_object_b(entry->literal())) {
 392         if (f != NULL) {
 393           f->do_oop((oop*)entry->literal_addr());
 394         }
 395         p = entry->next_addr();
 396       } else {
 397         *p = entry->next();
 398         context->free_entry(entry);
 399       }
 400       context->_num_processed++;
 401       entry = *p;
 402     }
 403   }
 404 }
 405 
 406 void StringTable::oops_do(OopClosure* f) {
 407   buckets_oops_do(f, 0, the_table()->table_size());
 408 }
 409 
 410 void StringTable::possibly_parallel_oops_do(OopClosure* f) {
 411   const int limit = the_table()->table_size();
 412 
 413   for (;;) {
 414     // Grab next set of buckets to scan
 415     int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
 416     if (start_idx >= limit) {
 417       // End of table
 418       break;
 419     }
 420 
 421     int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
 422     buckets_oops_do(f, start_idx, end_idx);
 423   }
 424 }
 425 
 426 // This verification is part of Universe::verify() and needs to be quick.
 427 // See StringTable::verify_and_compare() below for exhaustive verification.
 428 void StringTable::verify() {
 429   for (int i = 0; i < the_table()->table_size(); ++i) {
 430     HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
 431     for ( ; p != NULL; p = p->next()) {
 432       oop s = p->literal();
 433       guarantee(s != NULL, "interned string is NULL");
 434       unsigned int h = hash_string(s);
 435       guarantee(p->hash() == h, "broken hash in string table entry");
 436       guarantee(the_table()->hash_to_index(h) == i,
 437                 "wrong index in string table");
 438     }
 439   }
 440 }
 441 
 442 void StringTable::dump(outputStream* st, bool verbose) {
 443   if (!verbose) {
 444     the_table()->print_table_statistics(st, "StringTable");
 445   } else {
 446     Thread* THREAD = Thread::current();
 447     st->print_cr("VERSION: 1.1");
 448     for (int i = 0; i < the_table()->table_size(); ++i) {
 449       HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
 450       for ( ; p != NULL; p = p->next()) {
 451         oop s = p->literal();
 452         typeArrayOop value  = java_lang_String::value(s);
 453         int          length = java_lang_String::length(s);
 454         bool      is_latin1 = java_lang_String::is_latin1(s);
 455 
 456         if (length <= 0) {
 457           st->print("%d: ", length);
 458         } else {
 459           ResourceMark rm(THREAD);
 460           int utf8_length = length;
 461           char* utf8_string;
 462 
 463           if (!is_latin1) {
 464             jchar* chars = value->char_at_addr(0);
 465             utf8_string = UNICODE::as_utf8(chars, utf8_length);
 466           } else {
 467             jbyte* bytes = value->byte_at_addr(0);
 468             utf8_string = UNICODE::as_utf8(bytes, utf8_length);
 469           }
 470 
 471           st->print("%d: ", utf8_length);
 472           HashtableTextDump::put_utf8(st, utf8_string, utf8_length);
 473         }
 474         st->cr();
 475       }
 476     }
 477   }
 478 }
 479 
 480 StringTable::VerifyRetTypes StringTable::compare_entries(
 481                                       int bkt1, int e_cnt1,
 482                                       HashtableEntry<oop, mtSymbol>* e_ptr1,
 483                                       int bkt2, int e_cnt2,
 484                                       HashtableEntry<oop, mtSymbol>* e_ptr2) {
 485   // These entries are sanity checked by verify_and_compare_entries()
 486   // before this function is called.
 487   oop str1 = e_ptr1->literal();
 488   oop str2 = e_ptr2->literal();
 489 
 490   if (str1 == str2) {
 491     tty->print_cr("ERROR: identical oop values (0x" PTR_FORMAT ") "
 492                   "in entry @ bucket[%d][%d] and entry @ bucket[%d][%d]",
 493                   p2i(str1), bkt1, e_cnt1, bkt2, e_cnt2);
 494     return _verify_fail_continue;
 495   }
 496 
 497   if (java_lang_String::equals(str1, str2)) {
 498     tty->print_cr("ERROR: identical String values in entry @ "
 499                   "bucket[%d][%d] and entry @ bucket[%d][%d]",
 500                   bkt1, e_cnt1, bkt2, e_cnt2);
 501     return _verify_fail_continue;
 502   }
 503 
 504   return _verify_pass;
 505 }
 506 
 507 StringTable::VerifyRetTypes StringTable::verify_entry(int bkt, int e_cnt,
 508                                       HashtableEntry<oop, mtSymbol>* e_ptr,
 509                                       StringTable::VerifyMesgModes mesg_mode) {
 510 
 511   VerifyRetTypes ret = _verify_pass;  // be optimistic
 512 
 513   oop str = e_ptr->literal();
 514   if (str == NULL) {
 515     if (mesg_mode == _verify_with_mesgs) {
 516       tty->print_cr("ERROR: NULL oop value in entry @ bucket[%d][%d]", bkt,
 517                     e_cnt);
 518     }
 519     // NULL oop means no more verifications are possible
 520     return _verify_fail_done;
 521   }
 522 
 523   if (str->klass() != SystemDictionary::String_klass()) {
 524     if (mesg_mode == _verify_with_mesgs) {
 525       tty->print_cr("ERROR: oop is not a String in entry @ bucket[%d][%d]",
 526                     bkt, e_cnt);
 527     }
 528     // not a String means no more verifications are possible
 529     return _verify_fail_done;
 530   }
 531 
 532   unsigned int h = hash_string(str);
 533   if (e_ptr->hash() != h) {
 534     if (mesg_mode == _verify_with_mesgs) {
 535       tty->print_cr("ERROR: broken hash value in entry @ bucket[%d][%d], "
 536                     "bkt_hash=%d, str_hash=%d", bkt, e_cnt, e_ptr->hash(), h);
 537     }
 538     ret = _verify_fail_continue;
 539   }
 540 
 541   if (the_table()->hash_to_index(h) != bkt) {
 542     if (mesg_mode == _verify_with_mesgs) {
 543       tty->print_cr("ERROR: wrong index value for entry @ bucket[%d][%d], "
 544                     "str_hash=%d, hash_to_index=%d", bkt, e_cnt, h,
 545                     the_table()->hash_to_index(h));
 546     }
 547     ret = _verify_fail_continue;
 548   }
 549 
 550   return ret;
 551 }
 552 
 553 // See StringTable::verify() above for the quick verification that is
 554 // part of Universe::verify(). This verification is exhaustive and
 555 // reports on every issue that is found. StringTable::verify() only
 556 // reports on the first issue that is found.
 557 //
 558 // StringTable::verify_entry() checks:
 559 // - oop value != NULL (same as verify())
 560 // - oop value is a String
 561 // - hash(String) == hash in entry (same as verify())
 562 // - index for hash == index of entry (same as verify())
 563 //
 564 // StringTable::compare_entries() checks:
 565 // - oops are unique across all entries
 566 // - String values are unique across all entries
 567 //
 568 int StringTable::verify_and_compare_entries() {
 569   assert(StringTable_lock->is_locked(), "sanity check");
 570 
 571   int  fail_cnt = 0;
 572 
 573   // first, verify all the entries individually:
 574   for (int bkt = 0; bkt < the_table()->table_size(); bkt++) {
 575     HashtableEntry<oop, mtSymbol>* e_ptr = the_table()->bucket(bkt);
 576     for (int e_cnt = 0; e_ptr != NULL; e_ptr = e_ptr->next(), e_cnt++) {
 577       VerifyRetTypes ret = verify_entry(bkt, e_cnt, e_ptr, _verify_with_mesgs);
 578       if (ret != _verify_pass) {
 579         fail_cnt++;
 580       }
 581     }
 582   }
 583 
 584   // Optimization: if the above check did not find any failures, then
 585   // the comparison loop below does not need to call verify_entry()
 586   // before calling compare_entries(). If there were failures, then we
 587   // have to call verify_entry() to see if the entry can be passed to
 588   // compare_entries() safely. When we call verify_entry() in the loop
 589   // below, we do so quietly to void duplicate messages and we don't
 590   // increment fail_cnt because the failures have already been counted.
 591   bool need_entry_verify = (fail_cnt != 0);
 592 
 593   // second, verify all entries relative to each other:
 594   for (int bkt1 = 0; bkt1 < the_table()->table_size(); bkt1++) {
 595     HashtableEntry<oop, mtSymbol>* e_ptr1 = the_table()->bucket(bkt1);
 596     for (int e_cnt1 = 0; e_ptr1 != NULL; e_ptr1 = e_ptr1->next(), e_cnt1++) {
 597       if (need_entry_verify) {
 598         VerifyRetTypes ret = verify_entry(bkt1, e_cnt1, e_ptr1,
 599                                           _verify_quietly);
 600         if (ret == _verify_fail_done) {
 601           // cannot use the current entry to compare against other entries
 602           continue;
 603         }
 604       }
 605 
 606       for (int bkt2 = bkt1; bkt2 < the_table()->table_size(); bkt2++) {
 607         HashtableEntry<oop, mtSymbol>* e_ptr2 = the_table()->bucket(bkt2);
 608         int e_cnt2;
 609         for (e_cnt2 = 0; e_ptr2 != NULL; e_ptr2 = e_ptr2->next(), e_cnt2++) {
 610           if (bkt1 == bkt2 && e_cnt2 <= e_cnt1) {
 611             // skip the entries up to and including the one that
 612             // we're comparing against
 613             continue;
 614           }
 615 
 616           if (need_entry_verify) {
 617             VerifyRetTypes ret = verify_entry(bkt2, e_cnt2, e_ptr2,
 618                                               _verify_quietly);
 619             if (ret == _verify_fail_done) {
 620               // cannot compare against this entry
 621               continue;
 622             }
 623           }
 624 
 625           // compare two entries, report and count any failures:
 626           if (compare_entries(bkt1, e_cnt1, e_ptr1, bkt2, e_cnt2, e_ptr2)
 627               != _verify_pass) {
 628             fail_cnt++;
 629           }
 630         }
 631       }
 632     }
 633   }
 634   return fail_cnt;
 635 }
 636 
 637 // Create a new table and using alternate hash code, populate the new table
 638 // with the existing strings.   Set flag to use the alternate hash code afterwards.
 639 void StringTable::rehash_table() {
 640   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 641   // This should never happen with -Xshare:dump but it might in testing mode.
 642   if (DumpSharedSpaces) return;
 643   StringTable* new_table = new StringTable();
 644 
 645   // Rehash the table
 646   the_table()->move_to(new_table);
 647 
 648   // Delete the table and buckets (entries are reused in new table).
 649   delete _the_table;
 650   // Don't check if we need rehashing until the table gets unbalanced again.
 651   // Then rehash with a new global seed.
 652   _needs_rehashing = false;
 653   _the_table = new_table;
 654 }
 655 
 656 // Utility for dumping strings
 657 StringtableDCmd::StringtableDCmd(outputStream* output, bool heap) :
 658                                  DCmdWithParser(output, heap),
 659   _verbose("-verbose", "Dump the content of each string in the table",
 660            "BOOLEAN", false, "false") {
 661   _dcmdparser.add_dcmd_option(&_verbose);
 662 }
 663 
 664 void StringtableDCmd::execute(DCmdSource source, TRAPS) {
 665   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpStrings,
 666                          _verbose.value());
 667   VMThread::execute(&dumper);
 668 }
 669 
 670 int StringtableDCmd::num_arguments() {
 671   ResourceMark rm;
 672   StringtableDCmd* dcmd = new StringtableDCmd(NULL, false);
 673   if (dcmd != NULL) {
 674     DCmdMark mark(dcmd);
 675     return dcmd->_dcmdparser.num_arguments();
 676   } else {
 677     return 0;
 678   }
 679 }
 680 
 681 #if INCLUDE_CDS_JAVA_HEAP
 682 // Sharing
 683 oop StringTable::create_archived_string(oop s, Thread* THREAD) {
 684   assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
 685 
 686   oop new_s = NULL;
 687   typeArrayOop v = java_lang_String::value(s);
 688   typeArrayOop new_v = (typeArrayOop)MetaspaceShared::archive_heap_object(v, THREAD);
 689   if (new_v == NULL) {
 690     return NULL;
 691   }
 692   new_s = MetaspaceShared::archive_heap_object(s, THREAD);
 693   if (new_s == NULL) {
 694     return NULL;
 695   }
 696 
 697   // adjust the pointer to the 'value' field in the new String oop
 698   java_lang_String::set_value_raw(new_s, new_v);
 699   return new_s;
 700 }
 701 
 702 bool StringTable::copy_shared_string(GrowableArray<MemRegion> *string_space,
 703                                      CompactStringTableWriter* writer) {
 704   assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
 705 
 706   Thread* THREAD = Thread::current();
 707   G1CollectedHeap::heap()->begin_archive_alloc_range();
 708   for (int i = 0; i < the_table()->table_size(); ++i) {
 709     HashtableEntry<oop, mtSymbol>* bucket = the_table()->bucket(i);
 710     for ( ; bucket != NULL; bucket = bucket->next()) {
 711       oop s = bucket->literal();
 712       unsigned int hash = java_lang_String::hash_code(s);
 713       if (hash == 0) {
 714         continue;
 715       }
 716 
 717       java_lang_String::set_hash(s, hash);
 718       oop new_s = create_archived_string(s, THREAD);
 719       if (new_s == NULL) {
 720         continue;
 721       }
 722 
 723       // set the archived string in bucket
 724       bucket->set_literal(new_s);
 725 
 726       // add to the compact table
 727       writer->add(hash, new_s);
 728     }
 729   }
 730 
 731   G1CollectedHeap::heap()->end_archive_alloc_range(string_space, os::vm_allocation_granularity());
 732   return true;
 733 }
 734 
 735 void StringTable::write_to_archive(GrowableArray<MemRegion> *string_space) {
 736   assert(MetaspaceShared::is_heap_object_archiving_allowed(), "must be");
 737 
 738   _shared_table.reset();
 739   int num_buckets = the_table()->number_of_entries() /
 740                          SharedSymbolTableBucketSize;
 741   // calculation of num_buckets can result in zero buckets, we need at least one
 742   CompactStringTableWriter writer(num_buckets > 1 ? num_buckets : 1,
 743                                   &MetaspaceShared::stats()->string);
 744 
 745   // Copy the interned strings into the "string space" within the java heap
 746   if (copy_shared_string(string_space, &writer)) {
 747     writer.dump(&_shared_table);
 748   }
 749 }
 750 
 751 void StringTable::serialize(SerializeClosure* soc) {
 752   _shared_table.set_type(CompactHashtable<oop, char>::_string_table);
 753   _shared_table.serialize(soc);
 754 
 755   if (soc->writing()) {
 756     _shared_table.reset(); // Sanity. Make sure we don't use the shared table at dump time
 757   } else if (!_shared_string_mapped) {
 758     _shared_table.reset();
 759   }
 760 }
 761 
 762 void StringTable::shared_oops_do(OopClosure* f) {
 763   _shared_table.oops_do(f);
 764 }
 765 #endif //INCLUDE_CDS_JAVA_HEAP
 766 
--- EOF ---