1 /*
   2  * Copyright (c) 2003, 2018, 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/dictionary.inline.hpp"
  28 #include "classfile/protectionDomainCache.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "logging/log.hpp"
  31 #include "logging/logStream.hpp"
  32 #include "memory/iterator.hpp"
  33 #include "memory/metaspaceClosure.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "oops/oop.inline.hpp"
  36 #include "runtime/atomic.hpp"
  37 #include "runtime/orderAccess.hpp"
  38 #include "runtime/safepointVerifiers.hpp"
  39 #include "utilities/hashtable.inline.hpp"
  40 
  41 // Optimization: if any dictionary needs resizing, we set this flag,
  42 // so that we dont't have to walk all dictionaries to check if any actually
  43 // needs resizing, which is costly to do at Safepoint.
  44 bool Dictionary::_some_dictionary_needs_resizing = false;
  45 
  46 Dictionary::Dictionary(ClassLoaderData* loader_data, int table_size, bool resizable)
  47   : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry)),
  48     _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {
  49 };
  50 
  51 
  52 Dictionary::Dictionary(ClassLoaderData* loader_data,
  53                        int table_size, HashtableBucket<mtClass>* t,
  54                        int number_of_entries, bool resizable)
  55   : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry), t, number_of_entries),
  56     _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {
  57 };
  58 
  59 Dictionary::~Dictionary() {
  60   DictionaryEntry* probe = NULL;
  61   for (int index = 0; index < table_size(); index++) {
  62     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
  63       probe = *p;
  64       *p = probe->next();
  65       free_entry(probe);
  66     }
  67   }
  68   assert(number_of_entries() == 0, "should have removed all entries");
  69   assert(new_entry_free_list() == NULL, "entry present on Dictionary's free list");
  70 }
  71 
  72 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass) {
  73   DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::allocate_new_entry(hash, klass);
  74   entry->set_pd_set(NULL);
  75   assert(klass->is_instance_klass(), "Must be");
  76   return entry;
  77 }
  78 
  79 
  80 void Dictionary::free_entry(DictionaryEntry* entry) {
  81   // avoid recursion when deleting linked list
  82   // pd_set is accessed during a safepoint.
  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   // Unlink from the Hashtable prior to freeing
  89   unlink_entry(entry);
  90   FREE_C_HEAP_ARRAY(char, entry);
  91 }
  92 
  93 const int _resize_load_trigger = 5;       // load factor that will trigger the resize
  94 const double _resize_factor    = 2.0;     // by how much we will resize using current number of entries
  95 const int _resize_max_size     = 40423;   // the max dictionary size allowed
  96 const int _primelist[] = {107, 1009, 2017, 4049, 5051, 10103, 20201, _resize_max_size};
  97 const int _prime_array_size = sizeof(_primelist)/sizeof(int);
  98 
  99 // Calculate next "good" dictionary size based on requested count
 100 static int calculate_dictionary_size(int requested) {
 101   int newsize = _primelist[0];
 102   int index = 0;
 103   for (newsize = _primelist[index]; index < (_prime_array_size - 1);
 104        newsize = _primelist[++index]) {
 105     if (requested <= newsize) {
 106       break;
 107     }
 108   }
 109   return newsize;
 110 }
 111 
 112 bool Dictionary::does_any_dictionary_needs_resizing() {
 113   return Dictionary::_some_dictionary_needs_resizing;
 114 }
 115 
 116 void Dictionary::check_if_needs_resize() {
 117   if (_resizable == true) {
 118     if (number_of_entries() > (_resize_load_trigger*table_size())) {
 119       _needs_resizing = true;
 120       Dictionary::_some_dictionary_needs_resizing = true;
 121     }
 122   }
 123 }
 124 
 125 bool Dictionary::resize_if_needed() {
 126   int desired_size = 0;
 127   if (_needs_resizing == true) {
 128     desired_size = calculate_dictionary_size((int)(_resize_factor*number_of_entries()));
 129     if (desired_size >= _resize_max_size) {
 130       desired_size = _resize_max_size;
 131       // We have reached the limit, turn resizing off
 132       _resizable = false;
 133     }
 134     if ((desired_size != 0) && (desired_size != table_size())) {
 135       if (!resize(desired_size)) {
 136         // Something went wrong, turn resizing off
 137         _resizable = false;
 138       }
 139     }
 140   }
 141 
 142   _needs_resizing = false;
 143   Dictionary::_some_dictionary_needs_resizing = false;
 144 
 145   return (desired_size != 0);
 146 }
 147 
 148 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
 149 #ifdef ASSERT
 150   if (oopDesc::equals(protection_domain, instance_klass()->protection_domain())) {
 151     // Ensure this doesn't show up in the pd_set (invariant)
 152     bool in_pd_set = false;
 153     for (ProtectionDomainEntry* current = pd_set_acquire();
 154                                 current != NULL;
 155                                 current = current->next()) {
 156       if (oopDesc::equals(current->object_no_keepalive(), protection_domain)) {
 157         in_pd_set = true;
 158         break;
 159       }
 160     }
 161     if (in_pd_set) {
 162       assert(false, "A klass's protection domain should not show up "
 163                     "in its sys. dict. PD set");
 164     }
 165   }
 166 #endif /* ASSERT */
 167 
 168   if (oopDesc::equals(protection_domain, instance_klass()->protection_domain())) {
 169     // Succeeds trivially
 170     return true;
 171   }
 172 
 173   for (ProtectionDomainEntry* current = pd_set_acquire();
 174                               current != NULL;
 175                               current = current->next()) {
 176     if (oopDesc::equals(current->object_no_keepalive(), protection_domain)) return true;
 177   }
 178   return false;
 179 }
 180 
 181 
 182 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {
 183   assert_locked_or_safepoint(SystemDictionary_lock);
 184   if (!contains_protection_domain(protection_domain())) {
 185     ProtectionDomainCacheEntry* entry = SystemDictionary::cache_get(protection_domain);
 186     ProtectionDomainEntry* new_head =
 187                 new ProtectionDomainEntry(entry, pd_set());
 188     // Warning: Preserve store ordering.  The SystemDictionary is read
 189     //          without locks.  The new ProtectionDomainEntry must be
 190     //          complete before other threads can be allowed to see it
 191     //          via a store to _pd_set.
 192     release_set_pd_set(new_head);
 193   }
 194   LogTarget(Trace, protectiondomain) lt;
 195   if (lt.is_enabled()) {
 196     LogStream ls(lt);
 197     print_count(&ls);
 198   }
 199 }
 200 
 201 // During class loading we may have cached a protection domain that has
 202 // since been unreferenced, so this entry should be cleared.
 203 void Dictionary::clean_cached_protection_domains(DictionaryEntry* probe) {
 204   assert_locked_or_safepoint(SystemDictionary_lock);
 205 
 206   ProtectionDomainEntry* current = probe->pd_set();
 207   ProtectionDomainEntry* prev = NULL;
 208   while (current != NULL) {
 209     if (current->object_no_keepalive() == NULL) {
 210       LogTarget(Debug, protectiondomain) lt;
 211       if (lt.is_enabled()) {
 212         ResourceMark rm;
 213         // Print out trace information
 214         LogStream ls(lt);
 215         ls.print_cr("PD in set is not alive:");
 216         ls.print("class loader: "); loader_data()->class_loader()->print_value_on(&ls);
 217         ls.print(" loading: "); probe->instance_klass()->print_value_on(&ls);
 218         ls.cr();
 219       }
 220       if (probe->pd_set() == current) {
 221         probe->set_pd_set(current->next());
 222       } else {
 223         assert(prev != NULL, "should be set by alive entry");
 224         prev->set_next(current->next());
 225       }
 226       ProtectionDomainEntry* to_delete = current;
 227       current = current->next();
 228       delete to_delete;
 229     } else {
 230       prev = current;
 231       current = current->next();
 232     }
 233   }
 234 }
 235 
 236 
 237 void Dictionary::do_unloading() {
 238   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 239 
 240   // The NULL class loader doesn't initiate loading classes from other class loaders
 241   if (loader_data() == ClassLoaderData::the_null_class_loader_data()) {
 242     return;
 243   }
 244 
 245   // Remove unloaded entries and classes from this dictionary
 246   DictionaryEntry* probe = NULL;
 247   for (int index = 0; index < table_size(); index++) {
 248     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
 249       probe = *p;
 250       InstanceKlass* ik = probe->instance_klass();
 251       ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
 252 
 253       // If the klass that this loader initiated is dead,
 254       // (determined by checking the defining class loader)
 255       // remove this entry.
 256       if (k_def_class_loader_data->is_unloading()) {
 257         assert(k_def_class_loader_data != loader_data(),
 258                "cannot have live defining loader and unreachable klass");
 259         *p = probe->next();
 260         free_entry(probe);
 261         continue;
 262       }
 263       // Clean pd_set
 264       clean_cached_protection_domains(probe);
 265       p = probe->next_addr();
 266     }
 267   }
 268 }
 269 
 270 //   Just the classes from defining class loaders
 271 void Dictionary::classes_do(void f(InstanceKlass*)) {
 272   for (int index = 0; index < table_size(); index++) {
 273     for (DictionaryEntry* probe = bucket(index);
 274                           probe != NULL;
 275                           probe = probe->next()) {
 276       InstanceKlass* k = probe->instance_klass();
 277       if (loader_data() == k->class_loader_data()) {
 278         f(k);
 279       }
 280     }
 281   }
 282 }
 283 
 284 // Added for initialize_itable_for_klass to handle exceptions
 285 //   Just the classes from defining class loaders
 286 void Dictionary::classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
 287   for (int index = 0; index < table_size(); index++) {
 288     for (DictionaryEntry* probe = bucket(index);
 289                           probe != NULL;
 290                           probe = probe->next()) {
 291       InstanceKlass* k = probe->instance_klass();
 292       if (loader_data() == k->class_loader_data()) {
 293         f(k, CHECK);
 294       }
 295     }
 296   }
 297 }
 298 
 299 // All classes, and their class loaders, including initiating class loaders
 300 void Dictionary::all_entries_do(KlassClosure* closure) {
 301   for (int index = 0; index < table_size(); index++) {
 302     for (DictionaryEntry* probe = bucket(index);
 303                           probe != NULL;
 304                           probe = probe->next()) {
 305       InstanceKlass* k = probe->instance_klass();
 306       closure->do_klass(k);
 307     }
 308   }
 309 }
 310 
 311 // Used to scan and relocate the classes during CDS archive dump.
 312 void Dictionary::classes_do(MetaspaceClosure* it) {
 313   assert(DumpSharedSpaces, "dump-time only");
 314   for (int index = 0; index < table_size(); index++) {
 315     for (DictionaryEntry* probe = bucket(index);
 316                           probe != NULL;
 317                           probe = probe->next()) {
 318       it->push(probe->klass_addr());
 319     }
 320   }
 321 }
 322 
 323 
 324 
 325 // Add a loaded class to the dictionary.
 326 // Readers of the SystemDictionary aren't always locked, so _buckets
 327 // is volatile. The store of the next field in the constructor is
 328 // also cast to volatile;  we do this to ensure store order is maintained
 329 // by the compilers.
 330 
 331 void Dictionary::add_klass(unsigned int hash, Symbol* class_name,
 332                            InstanceKlass* obj) {
 333   assert_locked_or_safepoint(SystemDictionary_lock);
 334   assert(obj != NULL, "adding NULL obj");
 335   assert(obj->name() == class_name, "sanity check on name");
 336 
 337   DictionaryEntry* entry = new_entry(hash, obj);
 338   int index = hash_to_index(hash);
 339   add_entry(index, entry);
 340   check_if_needs_resize();
 341 }
 342 
 343 
 344 // This routine does not lock the dictionary.
 345 //
 346 // Since readers don't hold a lock, we must make sure that system
 347 // dictionary entries are only removed at a safepoint (when only one
 348 // thread is running), and are added to in a safe way (all links must
 349 // be updated in an MT-safe manner).
 350 //
 351 // Callers should be aware that an entry could be added just after
 352 // _buckets[index] is read here, so the caller will not see the new entry.
 353 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
 354                                        Symbol* class_name) {
 355   for (DictionaryEntry* entry = bucket(index);
 356                         entry != NULL;
 357                         entry = entry->next()) {
 358     if (entry->hash() == hash && entry->equals(class_name)) {
 359       return entry;
 360     }
 361   }
 362   return NULL;
 363 }
 364 
 365 
 366 InstanceKlass* Dictionary::find(unsigned int hash, Symbol* name,
 367                                 Handle protection_domain) {
 368   NoSafepointVerifier nsv;
 369 
 370   int index = hash_to_index(hash);
 371   DictionaryEntry* entry = get_entry(index, hash, name);
 372   if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
 373     return entry->instance_klass();
 374   } else {
 375     return NULL;
 376   }
 377 }
 378 
 379 
 380 InstanceKlass* Dictionary::find_class(int index, unsigned int hash,
 381                                       Symbol* name) {
 382   assert_locked_or_safepoint(SystemDictionary_lock);
 383   assert (index == index_for(name), "incorrect index?");
 384 
 385   DictionaryEntry* entry = get_entry(index, hash, name);
 386   return (entry != NULL) ? entry->instance_klass() : NULL;
 387 }
 388 
 389 
 390 void Dictionary::add_protection_domain(int index, unsigned int hash,
 391                                        InstanceKlass* klass,
 392                                        Handle protection_domain,
 393                                        TRAPS) {
 394   Symbol*  klass_name = klass->name();
 395   DictionaryEntry* entry = get_entry(index, hash, klass_name);
 396 
 397   assert(entry != NULL,"entry must be present, we just created it");
 398   assert(protection_domain() != NULL,
 399          "real protection domain should be present");
 400 
 401   entry->add_protection_domain(this, protection_domain);
 402 
 403 #ifdef ASSERT
 404   assert(loader_data() != ClassLoaderData::the_null_class_loader_data(), "doesn't make sense");
 405 #endif
 406 
 407   assert(entry->contains_protection_domain(protection_domain()),
 408          "now protection domain should be present");
 409 }
 410 
 411 
 412 bool Dictionary::is_valid_protection_domain(unsigned int hash,
 413                                             Symbol* name,
 414                                             Handle protection_domain) {
 415   int index = hash_to_index(hash);
 416   DictionaryEntry* entry = get_entry(index, hash, name);
 417   return entry->is_valid_protection_domain(protection_domain);
 418 }
 419 
 420 SymbolPropertyTable::SymbolPropertyTable(int table_size)
 421   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
 422 {
 423 }
 424 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
 425                                          int number_of_entries)
 426   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
 427 {
 428 }
 429 
 430 
 431 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
 432                                                      Symbol* sym,
 433                                                      intptr_t sym_mode) {
 434   assert(index == index_for(sym, sym_mode), "incorrect index?");
 435   for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 436     if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
 437       return p;
 438     }
 439   }
 440   return NULL;
 441 }
 442 
 443 
 444 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
 445                                                     Symbol* sym, intptr_t sym_mode) {
 446   assert_locked_or_safepoint(SystemDictionary_lock);
 447   assert(index == index_for(sym, sym_mode), "incorrect index?");
 448   assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
 449 
 450   SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
 451   Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
 452   return p;
 453 }
 454 
 455 void SymbolPropertyTable::oops_do(OopClosure* f) {
 456   for (int index = 0; index < table_size(); index++) {
 457     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 458       if (p->method_type() != NULL) {
 459         f->do_oop(p->method_type_addr());
 460       }
 461     }
 462   }
 463 }
 464 
 465 void SymbolPropertyTable::methods_do(void f(Method*)) {
 466   for (int index = 0; index < table_size(); index++) {
 467     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 468       Method* prop = p->method();
 469       if (prop != NULL) {
 470         f((Method*)prop);
 471       }
 472     }
 473   }
 474 }
 475 
 476 
 477 // ----------------------------------------------------------------------------
 478 
 479 void Dictionary::print_on(outputStream* st) const {
 480   ResourceMark rm;
 481 
 482   assert(loader_data() != NULL, "loader data should not be null");
 483   st->print_cr("Java dictionary (table_size=%d, classes=%d, resizable=%s)",
 484                table_size(), number_of_entries(), BOOL_TO_STR(_resizable));
 485   st->print_cr("^ indicates that initiating loader is different from defining loader");
 486 
 487   for (int index = 0; index < table_size(); index++) {
 488     for (DictionaryEntry* probe = bucket(index);
 489                           probe != NULL;
 490                           probe = probe->next()) {
 491       Klass* e = probe->instance_klass();
 492       bool is_defining_class =
 493          (loader_data() == e->class_loader_data());
 494       st->print("%4d: %s%s", index, is_defining_class ? " " : "^", e->external_name());
 495       ClassLoaderData* cld = e->class_loader_data();
 496       if (!loader_data()->is_the_null_class_loader_data()) {
 497         // Class loader output for the dictionary for the null class loader data is
 498         // redundant and obvious.
 499         st->print(", ");
 500         cld->print_value_on(st);
 501       }
 502       st->cr();
 503     }
 504   }
 505   tty->cr();
 506 }
 507 
 508 void DictionaryEntry::verify() {
 509   Klass* e = instance_klass();
 510   guarantee(e->is_instance_klass(),
 511                           "Verify of dictionary failed");
 512   e->verify();
 513   verify_protection_domain_set();
 514 }
 515 
 516 void Dictionary::verify() {
 517   guarantee(number_of_entries() >= 0, "Verify of dictionary failed");
 518 
 519   ClassLoaderData* cld = loader_data();
 520   // class loader must be present;  a null class loader is the
 521   // boostrap loader
 522   guarantee(cld != NULL ||
 523             cld->class_loader() == NULL ||
 524             cld->class_loader()->is_instance(),
 525             "checking type of class_loader");
 526 
 527   ResourceMark rm;
 528   stringStream tempst;
 529   tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
 530   verify_table<DictionaryEntry>(tempst.as_string());
 531 }