1 /*
   2  * Copyright (c) 2003, 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/classLoaderData.inline.hpp"
  27 #include "classfile/sharedClassUtil.hpp"
  28 #include "classfile/dictionary.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/systemDictionaryShared.hpp"
  31 #include "memory/iterator.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "oops/oop.inline.hpp"
  34 #include "runtime/orderAccess.inline.hpp"
  35 #include "utilities/hashtable.inline.hpp"
  36 
  37 DictionaryEntry*  Dictionary::_current_class_entry = NULL;
  38 int               Dictionary::_current_class_index =    0;
  39 
  40 size_t Dictionary::entry_size() {
  41   if (DumpSharedSpaces) {
  42     return SystemDictionaryShared::dictionary_entry_size();
  43   } else {
  44     return sizeof(DictionaryEntry);
  45   }
  46 }
  47 
  48 Dictionary::Dictionary(int table_size)
  49   : TwoOopHashtable<Klass*, mtClass>(table_size, (int)entry_size()) {
  50   _current_class_index = 0;
  51   _current_class_entry = NULL;
  52   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
  53 };
  54 
  55 
  56 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t,
  57                        int number_of_entries)
  58   : TwoOopHashtable<Klass*, mtClass>(table_size, (int)entry_size(), t, number_of_entries) {
  59   _current_class_index = 0;
  60   _current_class_entry = NULL;
  61   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
  62 };
  63 
  64 ProtectionDomainCacheEntry* Dictionary::cache_get(Handle protection_domain) {
  65   return _pd_cache_table->get(protection_domain);
  66 }
  67 
  68 DictionaryEntry* Dictionary::new_entry(unsigned int hash, Klass* klass,
  69                                        ClassLoaderData* loader_data) {
  70   DictionaryEntry* entry = (DictionaryEntry*)Hashtable<Klass*, mtClass>::new_entry(hash, klass);
  71   entry->set_loader_data(loader_data);
  72   entry->set_pd_set(NULL);
  73   assert(klass->is_instance_klass(), "Must be");
  74   if (DumpSharedSpaces) {
  75     SystemDictionaryShared::init_shared_dictionary_entry(klass, entry);
  76   }
  77   return entry;
  78 }
  79 
  80 
  81 void Dictionary::free_entry(DictionaryEntry* entry) {
  82   // avoid recursion when deleting linked list
  83   while (entry->pd_set() != NULL) {
  84     ProtectionDomainEntry* to_delete = entry->pd_set();
  85     entry->set_pd_set(to_delete->next());
  86     delete to_delete;
  87   }
  88   Hashtable<Klass*, mtClass>::free_entry(entry);
  89 }
  90 
  91 
  92 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
  93 #ifdef ASSERT
  94   if (protection_domain == klass()->protection_domain()) {
  95     // Ensure this doesn't show up in the pd_set (invariant)
  96     bool in_pd_set = false;
  97     for (ProtectionDomainEntry* current = _pd_set;
  98                                 current != NULL;
  99                                 current = current->next()) {
 100       if (current->protection_domain() == protection_domain) {
 101         in_pd_set = true;
 102         break;
 103       }
 104     }
 105     if (in_pd_set) {
 106       assert(false, "A klass's protection domain should not show up "
 107                     "in its sys. dict. PD set");
 108     }
 109   }
 110 #endif /* ASSERT */
 111 
 112   if (protection_domain == klass()->protection_domain()) {
 113     // Succeeds trivially
 114     return true;
 115   }
 116 
 117   for (ProtectionDomainEntry* current = _pd_set;
 118                               current != NULL;
 119                               current = current->next()) {
 120     if (current->protection_domain() == protection_domain) return true;
 121   }
 122   return false;
 123 }
 124 
 125 
 126 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {
 127   assert_locked_or_safepoint(SystemDictionary_lock);
 128   if (!contains_protection_domain(protection_domain())) {
 129     ProtectionDomainCacheEntry* entry = dict->cache_get(protection_domain);
 130     ProtectionDomainEntry* new_head =
 131                 new ProtectionDomainEntry(entry, _pd_set);
 132     // Warning: Preserve store ordering.  The SystemDictionary is read
 133     //          without locks.  The new ProtectionDomainEntry must be
 134     //          complete before other threads can be allowed to see it
 135     //          via a store to _pd_set.
 136     OrderAccess::release_store_ptr(&_pd_set, new_head);
 137   }
 138   if (log_is_enabled(Trace, protectiondomain)) {
 139     ResourceMark rm;
 140     outputStream* log = Log(protectiondomain)::trace_stream();
 141     print_count(log);
 142   }
 143 }
 144 
 145 
 146 void Dictionary::do_unloading() {
 147   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 148 
 149   // Remove unloadable entries and classes from system dictionary
 150   // The placeholder array has been handled in always_strong_oops_do.
 151   DictionaryEntry* probe = NULL;
 152   for (int index = 0; index < table_size(); index++) {
 153     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
 154       probe = *p;
 155       Klass* e = probe->klass();
 156       ClassLoaderData* loader_data = probe->loader_data();
 157 
 158       InstanceKlass* ik = InstanceKlass::cast(e);
 159 
 160       // Non-unloadable classes were handled in always_strong_oops_do
 161       if (!is_strongly_reachable(loader_data, e)) {
 162         // Entry was not visited in phase1 (negated test from phase1)
 163         assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
 164         ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
 165 
 166         // Do we need to delete this system dictionary entry?
 167         bool purge_entry = false;
 168 
 169         // Do we need to delete this system dictionary entry?
 170         if (loader_data->is_unloading()) {
 171           // If the loader is not live this entry should always be
 172           // removed (will never be looked up again).
 173           purge_entry = true;
 174         } else {
 175           // The loader in this entry is alive. If the klass is dead,
 176           // (determined by checking the defining class loader)
 177           // the loader must be an initiating loader (rather than the
 178           // defining loader). Remove this entry.
 179           if (k_def_class_loader_data->is_unloading()) {
 180             // If we get here, the class_loader_data must not be the defining
 181             // loader, it must be an initiating one.
 182             assert(k_def_class_loader_data != loader_data,
 183                    "cannot have live defining loader and unreachable klass");
 184             // Loader is live, but class and its defining loader are dead.
 185             // Remove the entry. The class is going away.
 186             purge_entry = true;
 187           }
 188         }
 189 
 190         if (purge_entry) {
 191           *p = probe->next();
 192           if (probe == _current_class_entry) {
 193             _current_class_entry = NULL;
 194           }
 195           free_entry(probe);
 196           continue;
 197         }
 198       }
 199       p = probe->next_addr();
 200     }
 201   }
 202 }
 203 
 204 void Dictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
 205   // Skip the strong roots probe marking if the closures are the same.
 206   if (strong == weak) {
 207     oops_do(strong);
 208     return;
 209   }
 210 
 211   for (int index = 0; index < table_size(); index++) {
 212     for (DictionaryEntry *probe = bucket(index);
 213                           probe != NULL;
 214                           probe = probe->next()) {
 215       Klass* e = probe->klass();
 216       ClassLoaderData* loader_data = probe->loader_data();
 217       if (is_strongly_reachable(loader_data, e)) {
 218         probe->set_strongly_reachable();
 219       }
 220     }
 221   }
 222   _pd_cache_table->roots_oops_do(strong, weak);
 223 }
 224 
 225 void Dictionary::remove_classes_in_error_state() {
 226   assert(DumpSharedSpaces, "supported only when dumping");
 227   DictionaryEntry* probe = NULL;
 228   for (int index = 0; index < table_size(); index++) {
 229     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
 230       probe = *p;
 231       InstanceKlass* ik = InstanceKlass::cast(probe->klass());
 232       if (ik->is_in_error_state()) { // purge this entry
 233         *p = probe->next();
 234         if (probe == _current_class_entry) {
 235           _current_class_entry = NULL;
 236         }
 237         free_entry(probe);
 238         ResourceMark rm;
 239         tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name());
 240         continue;
 241       }
 242 
 243       p = probe->next_addr();
 244     }
 245   }
 246 }
 247 
 248 void Dictionary::always_strong_oops_do(OopClosure* blk) {
 249   // Follow all system classes and temporary placeholders in dictionary; only
 250   // protection domain oops contain references into the heap. In a first
 251   // pass over the system dictionary determine which need to be treated as
 252   // strongly reachable and mark them as such.
 253   for (int index = 0; index < table_size(); index++) {
 254     for (DictionaryEntry *probe = bucket(index);
 255                           probe != NULL;
 256                           probe = probe->next()) {
 257       Klass* e = probe->klass();
 258       ClassLoaderData* loader_data = probe->loader_data();
 259       if (is_strongly_reachable(loader_data, e)) {
 260         probe->set_strongly_reachable();
 261       }
 262     }
 263   }
 264   // Then iterate over the protection domain cache to apply the closure on the
 265   // previously marked ones.
 266   _pd_cache_table->always_strong_oops_do(blk);
 267 }
 268 
 269 
 270 void Dictionary::always_strong_classes_do(KlassClosure* closure) {
 271   // Follow all system classes and temporary placeholders in dictionary
 272   for (int index = 0; index < table_size(); index++) {
 273     for (DictionaryEntry* probe = bucket(index);
 274                           probe != NULL;
 275                           probe = probe->next()) {
 276       Klass* e = probe->klass();
 277       ClassLoaderData* loader_data = probe->loader_data();
 278       if (is_strongly_reachable(loader_data, e)) {
 279         closure->do_klass(e);
 280       }
 281     }
 282   }
 283 }
 284 
 285 
 286 //   Just the classes from defining class loaders
 287 void Dictionary::classes_do(void f(Klass*)) {
 288   for (int index = 0; index < table_size(); index++) {
 289     for (DictionaryEntry* probe = bucket(index);
 290                           probe != NULL;
 291                           probe = probe->next()) {
 292       Klass* k = probe->klass();
 293       if (probe->loader_data() == k->class_loader_data()) {
 294         f(k);
 295       }
 296     }
 297   }
 298 }
 299 
 300 // Added for initialize_itable_for_klass to handle exceptions
 301 //   Just the classes from defining class loaders
 302 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
 303   for (int index = 0; index < table_size(); index++) {
 304     for (DictionaryEntry* probe = bucket(index);
 305                           probe != NULL;
 306                           probe = probe->next()) {
 307       Klass* k = probe->klass();
 308       if (probe->loader_data() == k->class_loader_data()) {
 309         f(k, CHECK);
 310       }
 311     }
 312   }
 313 }
 314 
 315 //   All classes, and their class loaders
 316 // Don't iterate over placeholders
 317 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
 318   for (int index = 0; index < table_size(); index++) {
 319     for (DictionaryEntry* probe = bucket(index);
 320                           probe != NULL;
 321                           probe = probe->next()) {
 322       Klass* k = probe->klass();
 323       f(k, probe->loader_data());
 324     }
 325   }
 326 }
 327 
 328 void Dictionary::oops_do(OopClosure* f) {
 329   // Only the protection domain oops contain references into the heap. Iterate
 330   // over all of them.
 331   _pd_cache_table->oops_do(f);
 332 }
 333 
 334 void Dictionary::methods_do(void f(Method*)) {
 335   for (int index = 0; index < table_size(); index++) {
 336     for (DictionaryEntry* probe = bucket(index);
 337                           probe != NULL;
 338                           probe = probe->next()) {
 339       Klass* k = probe->klass();
 340       if (probe->loader_data() == k->class_loader_data()) {
 341         // only take klass is we have the entry with the defining class loader
 342         InstanceKlass::cast(k)->methods_do(f);
 343       }
 344     }
 345   }
 346 }
 347 
 348 void Dictionary::unlink(BoolObjectClosure* is_alive) {
 349   // Only the protection domain cache table may contain references to the heap
 350   // that need to be unlinked.
 351   _pd_cache_table->unlink(is_alive);
 352 }
 353 
 354 Klass* Dictionary::try_get_next_class() {
 355   while (true) {
 356     if (_current_class_entry != NULL) {
 357       Klass* k = _current_class_entry->klass();
 358       _current_class_entry = _current_class_entry->next();
 359       return k;
 360     }
 361     _current_class_index = (_current_class_index + 1) % table_size();
 362     _current_class_entry = bucket(_current_class_index);
 363   }
 364   // never reached
 365 }
 366 
 367 // Add a loaded class to the system dictionary.
 368 // Readers of the SystemDictionary aren't always locked, so _buckets
 369 // is volatile. The store of the next field in the constructor is
 370 // also cast to volatile;  we do this to ensure store order is maintained
 371 // by the compilers.
 372 
 373 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data,
 374                            KlassHandle obj) {
 375   assert_locked_or_safepoint(SystemDictionary_lock);
 376   assert(obj() != NULL, "adding NULL obj");
 377   assert(obj()->name() == class_name, "sanity check on name");
 378   assert(loader_data != NULL, "Must be non-NULL");
 379 
 380   unsigned int hash = compute_hash(class_name, loader_data);
 381   int index = hash_to_index(hash);
 382   DictionaryEntry* entry = new_entry(hash, obj(), loader_data);
 383   add_entry(index, entry);
 384 }
 385 
 386 
 387 // This routine does not lock the system dictionary.
 388 //
 389 // Since readers don't hold a lock, we must make sure that system
 390 // dictionary entries are only removed at a safepoint (when only one
 391 // thread is running), and are added to in a safe way (all links must
 392 // be updated in an MT-safe manner).
 393 //
 394 // Callers should be aware that an entry could be added just after
 395 // _buckets[index] is read here, so the caller will not see the new entry.
 396 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
 397                                        Symbol* class_name,
 398                                        ClassLoaderData* loader_data) {
 399   DEBUG_ONLY(_lookup_count++);
 400   for (DictionaryEntry* entry = bucket(index);
 401                         entry != NULL;
 402                         entry = entry->next()) {
 403     if (entry->hash() == hash && entry->equals(class_name, loader_data)) {
 404       DEBUG_ONLY(bucket_count_hit(index));
 405       return entry;
 406     }
 407     DEBUG_ONLY(_lookup_length++);
 408   }
 409   return NULL;
 410 }
 411 
 412 
 413 Klass* Dictionary::find(int index, unsigned int hash, Symbol* name,
 414                           ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
 415   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
 416   if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
 417     return entry->klass();
 418   } else {
 419     return NULL;
 420   }
 421 }
 422 
 423 
 424 Klass* Dictionary::find_class(int index, unsigned int hash,
 425                                 Symbol* name, ClassLoaderData* loader_data) {
 426   assert_locked_or_safepoint(SystemDictionary_lock);
 427   assert (index == index_for(name, loader_data), "incorrect index?");
 428 
 429   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
 430   return (entry != NULL) ? entry->klass() : (Klass*)NULL;
 431 }
 432 
 433 
 434 // Variant of find_class for shared classes.  No locking required, as
 435 // that table is static.
 436 
 437 Klass* Dictionary::find_shared_class(int index, unsigned int hash,
 438                                        Symbol* name) {
 439   assert (index == index_for(name, NULL), "incorrect index?");
 440 
 441   DictionaryEntry* entry = get_entry(index, hash, name, NULL);
 442   return (entry != NULL) ? entry->klass() : (Klass*)NULL;
 443 }
 444 
 445 
 446 void Dictionary::add_protection_domain(int index, unsigned int hash,
 447                                        instanceKlassHandle klass,
 448                                        ClassLoaderData* loader_data, Handle protection_domain,
 449                                        TRAPS) {
 450   Symbol*  klass_name = klass->name();
 451   DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data);
 452 
 453   assert(entry != NULL,"entry must be present, we just created it");
 454   assert(protection_domain() != NULL,
 455          "real protection domain should be present");
 456 
 457   entry->add_protection_domain(this, protection_domain);
 458 
 459   assert(entry->contains_protection_domain(protection_domain()),
 460          "now protection domain should be present");
 461 }
 462 
 463 
 464 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
 465                                             Symbol* name,
 466                                             ClassLoaderData* loader_data,
 467                                             Handle protection_domain) {
 468   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
 469   return entry->is_valid_protection_domain(protection_domain);
 470 }
 471 
 472 
 473 void Dictionary::reorder_dictionary() {
 474 
 475   // Copy all the dictionary entries into a single master list.
 476 
 477   DictionaryEntry* master_list = NULL;
 478   for (int i = 0; i < table_size(); ++i) {
 479     DictionaryEntry* p = bucket(i);
 480     while (p != NULL) {
 481       DictionaryEntry* tmp;
 482       tmp = p->next();
 483       p->set_next(master_list);
 484       master_list = p;
 485       p = tmp;
 486     }
 487     set_entry(i, NULL);
 488   }
 489 
 490   // Add the dictionary entries back to the list in the correct buckets.
 491   while (master_list != NULL) {
 492     DictionaryEntry* p = master_list;
 493     master_list = master_list->next();
 494     p->set_next(NULL);
 495     Symbol* class_name = p->klass()->name();
 496     // Since the null class loader data isn't copied to the CDS archive,
 497     // compute the hash with NULL for loader data.
 498     unsigned int hash = compute_hash(class_name, NULL);
 499     int index = hash_to_index(hash);
 500     p->set_hash(hash);
 501     p->set_loader_data(NULL);   // loader_data isn't copied to CDS
 502     p->set_next(bucket(index));
 503     set_entry(index, p);
 504   }
 505 }
 506 
 507 
 508 unsigned int ProtectionDomainCacheTable::compute_hash(Handle protection_domain) {
 509   // Identity hash can safepoint, so keep protection domain in a Handle.
 510   return (unsigned int)(protection_domain->identity_hash());
 511 }
 512 
 513 int ProtectionDomainCacheTable::index_for(Handle protection_domain) {
 514   return hash_to_index(compute_hash(protection_domain));
 515 }
 516 
 517 ProtectionDomainCacheTable::ProtectionDomainCacheTable(int table_size)
 518   : Hashtable<oop, mtClass>(table_size, sizeof(ProtectionDomainCacheEntry))
 519 {
 520 }
 521 
 522 void ProtectionDomainCacheTable::unlink(BoolObjectClosure* is_alive) {
 523   assert(SafepointSynchronize::is_at_safepoint(), "must be");
 524   for (int i = 0; i < table_size(); ++i) {
 525     ProtectionDomainCacheEntry** p = bucket_addr(i);
 526     ProtectionDomainCacheEntry* entry = bucket(i);
 527     while (entry != NULL) {
 528       if (is_alive->do_object_b(entry->literal())) {
 529         p = entry->next_addr();
 530       } else {
 531         *p = entry->next();
 532         free_entry(entry);
 533       }
 534       entry = *p;
 535     }
 536   }
 537 }
 538 
 539 void ProtectionDomainCacheTable::oops_do(OopClosure* f) {
 540   for (int index = 0; index < table_size(); index++) {
 541     for (ProtectionDomainCacheEntry* probe = bucket(index);
 542                                      probe != NULL;
 543                                      probe = probe->next()) {
 544       probe->oops_do(f);
 545     }
 546   }
 547 }
 548 
 549 void ProtectionDomainCacheTable::roots_oops_do(OopClosure* strong, OopClosure* weak) {
 550   for (int index = 0; index < table_size(); index++) {
 551     for (ProtectionDomainCacheEntry* probe = bucket(index);
 552                                      probe != NULL;
 553                                      probe = probe->next()) {
 554       if (probe->is_strongly_reachable()) {
 555         probe->reset_strongly_reachable();
 556         probe->oops_do(strong);
 557       } else {
 558         if (weak != NULL) {
 559           probe->oops_do(weak);
 560         }
 561       }
 562     }
 563   }
 564 }
 565 
 566 uint ProtectionDomainCacheTable::bucket_size() {
 567   return sizeof(ProtectionDomainCacheEntry);
 568 }
 569 
 570 #ifndef PRODUCT
 571 void ProtectionDomainCacheTable::print() {
 572   tty->print_cr("Protection domain cache table (table_size=%d, classes=%d)",
 573                 table_size(), number_of_entries());
 574   for (int index = 0; index < table_size(); index++) {
 575     for (ProtectionDomainCacheEntry* probe = bucket(index);
 576                                      probe != NULL;
 577                                      probe = probe->next()) {
 578       probe->print();
 579     }
 580   }
 581 }
 582 
 583 void ProtectionDomainCacheEntry::print() {
 584   tty->print_cr("entry " PTR_FORMAT " value " PTR_FORMAT " strongly_reachable %d next " PTR_FORMAT,
 585                 p2i(this), p2i(literal()), _strongly_reachable, p2i(next()));
 586 }
 587 #endif
 588 
 589 void ProtectionDomainCacheTable::verify() {
 590   int element_count = 0;
 591   for (int index = 0; index < table_size(); index++) {
 592     for (ProtectionDomainCacheEntry* probe = bucket(index);
 593                                      probe != NULL;
 594                                      probe = probe->next()) {
 595       probe->verify();
 596       element_count++;
 597     }
 598   }
 599   guarantee(number_of_entries() == element_count,
 600             "Verify of protection domain cache table failed");
 601   DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Domain Cache Table"));
 602 }
 603 
 604 void ProtectionDomainCacheEntry::verify() {
 605   guarantee(literal()->is_oop(), "must be an oop");
 606 }
 607 
 608 void ProtectionDomainCacheTable::always_strong_oops_do(OopClosure* f) {
 609   // the caller marked the protection domain cache entries that we need to apply
 610   // the closure on. Only process them.
 611   for (int index = 0; index < table_size(); index++) {
 612     for (ProtectionDomainCacheEntry* probe = bucket(index);
 613                                      probe != NULL;
 614                                      probe = probe->next()) {
 615       if (probe->is_strongly_reachable()) {
 616         probe->reset_strongly_reachable();
 617         probe->oops_do(f);
 618       }
 619     }
 620   }
 621 }
 622 
 623 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::get(Handle protection_domain) {
 624   unsigned int hash = compute_hash(protection_domain);
 625   int index = hash_to_index(hash);
 626 
 627   ProtectionDomainCacheEntry* entry = find_entry(index, protection_domain);
 628   if (entry == NULL) {
 629     entry = add_entry(index, hash, protection_domain);
 630   }
 631   return entry;
 632 }
 633 
 634 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::find_entry(int index, Handle protection_domain) {
 635   for (ProtectionDomainCacheEntry* e = bucket(index); e != NULL; e = e->next()) {
 636     if (e->protection_domain() == protection_domain()) {
 637       return e;
 638     }
 639   }
 640 
 641   return NULL;
 642 }
 643 
 644 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::add_entry(int index, unsigned int hash, Handle protection_domain) {
 645   assert_locked_or_safepoint(SystemDictionary_lock);
 646   assert(index == index_for(protection_domain), "incorrect index?");
 647   assert(find_entry(index, protection_domain) == NULL, "no double entry");
 648 
 649   ProtectionDomainCacheEntry* p = new_entry(hash, protection_domain);
 650   Hashtable<oop, mtClass>::add_entry(index, p);
 651   return p;
 652 }
 653 
 654 void ProtectionDomainCacheTable::free(ProtectionDomainCacheEntry* to_delete) {
 655   unsigned int hash = compute_hash(Handle(Thread::current(), to_delete->protection_domain()));
 656   int index = hash_to_index(hash);
 657 
 658   ProtectionDomainCacheEntry** p = bucket_addr(index);
 659   ProtectionDomainCacheEntry* entry = bucket(index);
 660   while (true) {
 661     assert(entry != NULL, "sanity");
 662 
 663     if (entry == to_delete) {
 664       *p = entry->next();
 665       Hashtable<oop, mtClass>::free_entry(entry);
 666       break;
 667     } else {
 668       p = entry->next_addr();
 669       entry = *p;
 670     }
 671   }
 672 }
 673 
 674 SymbolPropertyTable::SymbolPropertyTable(int table_size)
 675   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
 676 {
 677 }
 678 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
 679                                          int number_of_entries)
 680   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
 681 {
 682 }
 683 
 684 
 685 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
 686                                                      Symbol* sym,
 687                                                      intptr_t sym_mode) {
 688   assert(index == index_for(sym, sym_mode), "incorrect index?");
 689   for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 690     if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
 691       return p;
 692     }
 693   }
 694   return NULL;
 695 }
 696 
 697 
 698 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
 699                                                     Symbol* sym, intptr_t sym_mode) {
 700   assert_locked_or_safepoint(SystemDictionary_lock);
 701   assert(index == index_for(sym, sym_mode), "incorrect index?");
 702   assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
 703 
 704   SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
 705   Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
 706   return p;
 707 }
 708 
 709 void SymbolPropertyTable::oops_do(OopClosure* f) {
 710   for (int index = 0; index < table_size(); index++) {
 711     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 712       if (p->method_type() != NULL) {
 713         f->do_oop(p->method_type_addr());
 714       }
 715     }
 716   }
 717 }
 718 
 719 void SymbolPropertyTable::methods_do(void f(Method*)) {
 720   for (int index = 0; index < table_size(); index++) {
 721     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 722       Method* prop = p->method();
 723       if (prop != NULL) {
 724         f((Method*)prop);
 725       }
 726     }
 727   }
 728 }
 729 
 730 
 731 // ----------------------------------------------------------------------------
 732 
 733 void Dictionary::print(bool details) {
 734   ResourceMark rm;
 735 
 736   if (details) {
 737     tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
 738                    table_size(), number_of_entries());
 739     tty->print_cr("^ indicates that initiating loader is different from "
 740                   "defining loader");
 741   }
 742 
 743   for (int index = 0; index < table_size(); index++) {
 744     for (DictionaryEntry* probe = bucket(index);
 745                           probe != NULL;
 746                           probe = probe->next()) {
 747       Klass* e = probe->klass();
 748       ClassLoaderData* loader_data =  probe->loader_data();
 749       bool is_defining_class =
 750          (loader_data == e->class_loader_data());
 751       if (details) {
 752         tty->print("%4d: ", index);
 753       }
 754       tty->print("%s%s", ((!details) || is_defining_class) ? " " : "^",
 755                  e->external_name());
 756 
 757       if (details) {
 758         tty->print(", loader ");
 759         if (loader_data != NULL) {
 760           loader_data->print_value();
 761         } else {
 762           tty->print("NULL");
 763         }
 764       }
 765       tty->cr();
 766     }
 767   }
 768 
 769   if (details) {
 770     tty->cr();
 771     _pd_cache_table->print();
 772   }
 773   tty->cr();
 774 }
 775 
 776 #ifdef ASSERT
 777 void Dictionary::printPerformanceInfoDetails() {
 778   if (log_is_enabled(Info, hashtables)) {
 779     ResourceMark rm;
 780 
 781     log_info(hashtables)(" ");
 782     log_info(hashtables)("Java system dictionary (table_size=%d, classes=%d)",
 783                             table_size(), number_of_entries());
 784     log_info(hashtables)("1st number: the bucket index");
 785     log_info(hashtables)("2nd number: the hit percentage for this bucket");
 786     log_info(hashtables)("3rd number: the entry's index within this bucket");
 787     log_info(hashtables)("4th number: the hash index of this entry");
 788     log_info(hashtables)(" ");
 789 
 790     // find top buckets with highest lookup count
 791 #define TOP_COUNT 16
 792     int topItemsIndicies[TOP_COUNT];
 793     for (int i = 0; i < TOP_COUNT; i++) {
 794       topItemsIndicies[i] = i;
 795     }
 796     double total = 0.0;
 797     for (int i = 0; i < table_size(); i++) {
 798       // find the total count number, so later on we can
 799       // express bucket lookup count as a percentage of all lookups
 800       unsigned value = bucket_hits(i);
 801       total += value;
 802 
 803       // find the top entry with min value
 804       int min_index = 0;
 805       unsigned min_value = bucket_hits(topItemsIndicies[min_index]);
 806       for (int j = 1; j < TOP_COUNT; j++) {
 807         unsigned top_value = bucket_hits(topItemsIndicies[j]);
 808         if (top_value < min_value) {
 809           min_value = top_value;
 810           min_index = j;
 811         }
 812       }
 813       // if the bucket loookup value is bigger than the top buckets min
 814       // move that bucket index into the top list
 815       if (value > min_value) {
 816         topItemsIndicies[min_index] = i;
 817       }
 818     }
 819 
 820     for (int index = 0; index < table_size(); index++) {
 821       double percentage = 100.0 * (double)bucket_hits(index)/total;
 822       int chain = 0;
 823       for (DictionaryEntry* probe = bucket(index);
 824            probe != NULL;
 825            probe = probe->next()) {
 826         Klass* e = probe->klass();
 827         ClassLoaderData* loader_data =  probe->loader_data();
 828         bool is_defining_class =
 829         (loader_data == e->class_loader_data());
 830         log_info(hashtables)("%4d: %5.2f%%: %3d: %10u: %s, loader %s",
 831                                 index, percentage, chain, probe->hash(), e->external_name(),
 832                                 (loader_data != NULL) ? loader_data->loader_name() : "NULL");
 833 
 834         chain++;
 835       }
 836       if (chain == 0) {
 837         log_info(hashtables)("%4d:", index+1);
 838       }
 839     }
 840     log_info(hashtables)(" ");
 841 
 842     // print out the TOP_COUNT of buckets with highest lookup count (unsorted)
 843     log_info(hashtables)("Top %d buckets:", TOP_COUNT);
 844     for (int i = 0; i < TOP_COUNT; i++) {
 845       log_info(hashtables)("%4d: hits %5.2f%%",
 846                               topItemsIndicies[i],
 847                                 100.0*(double)bucket_hits(topItemsIndicies[i])/total);
 848     }
 849   }
 850 }
 851 #endif // ASSERT
 852 
 853 void Dictionary::verify() {
 854   guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
 855 
 856   int element_count = 0;
 857   for (int index = 0; index < table_size(); index++) {
 858     for (DictionaryEntry* probe = bucket(index);
 859                           probe != NULL;
 860                           probe = probe->next()) {
 861       Klass* e = probe->klass();
 862       ClassLoaderData* loader_data = probe->loader_data();
 863       guarantee(e->is_instance_klass(),
 864                               "Verify of system dictionary failed");
 865       // class loader must be present;  a null class loader is the
 866       // boostrap loader
 867       guarantee(loader_data != NULL || DumpSharedSpaces ||
 868                 loader_data->class_loader() == NULL ||
 869                 loader_data->class_loader()->is_instance(),
 870                 "checking type of class_loader");
 871       e->verify();
 872       probe->verify_protection_domain_set();
 873       element_count++;
 874     }
 875   }
 876   guarantee(number_of_entries() == element_count,
 877             "Verify of system dictionary failed");
 878 #ifdef ASSERT
 879   if (!verify_lookup_length((double)number_of_entries() / table_size(), "System Dictionary")) {
 880     this->printPerformanceInfoDetails();
 881   }
 882 #endif // ASSERT
 883 
 884   _pd_cache_table->verify();
 885 }
 886