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   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.
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   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).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 // A ClassLoaderData identifies the full set of class types that a class
  26 // loader's name resolution strategy produces for a given configuration of the
  27 // class loader.
  28 // Class types in the ClassLoaderData may be defined by from class file binaries
  29 // provided by the class loader, or from other class loader it interacts with
  30 // according to its name resolution strategy.
  31 //
  32 // Class loaders that implement a deterministic name resolution strategy
  33 // (including with respect to their delegation behavior), such as the boot, the
  34 // platform, and the system loaders of the JDK's built-in class loader
  35 // hierarchy, always produce the same linkset for a given configuration.
  36 //
  37 // ClassLoaderData carries information related to a linkset (e.g.,
  38 // metaspace holding its klass definitions).
  39 // The System Dictionary and related data structures (e.g., placeholder table,
  40 // loader constraints table) as well as the runtime representation of classes
  41 // only reference ClassLoaderData.
  42 //
  43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
  44 // that represent the loader's "linking domain" in the JVM.
  45 //
  46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
  47 // the singleton class the_null_class_loader_data().
  48 
  49 #include "precompiled.hpp"
  50 #include "classfile/classLoaderData.inline.hpp"
  51 #include "classfile/classLoaderDataGraph.inline.hpp"
  52 #include "classfile/dictionary.hpp"
  53 #include "classfile/javaClasses.hpp"
  54 #include "classfile/moduleEntry.hpp"
  55 #include "classfile/packageEntry.hpp"
  56 #include "classfile/symbolTable.hpp"
  57 #include "classfile/systemDictionary.hpp"
  58 #include "classfile/systemDictionaryShared.hpp"
  59 #include "classfile/vmClasses.hpp"
  60 #include "logging/log.hpp"
  61 #include "logging/logStream.hpp"
  62 #include "memory/allocation.inline.hpp"
  63 #include "memory/classLoaderMetaspace.hpp"
  64 #include "memory/metadataFactory.hpp"
  65 #include "memory/metaspace.hpp"
  66 #include "memory/resourceArea.hpp"
  67 #include "memory/universe.hpp"
  68 #include "oops/access.inline.hpp"
  69 #include "oops/klass.inline.hpp"
  70 #include "oops/objArrayKlass.hpp"
  71 #include "oops/oop.inline.hpp"
  72 #include "oops/oopHandle.inline.hpp"
  73 #include "oops/weakHandle.inline.hpp"
  74 #include "runtime/arguments.hpp"
  75 #include "runtime/atomic.hpp"
  76 #include "runtime/handles.inline.hpp"
  77 #include "runtime/mutex.hpp"
  78 #include "runtime/safepoint.hpp"
  79 #include "utilities/growableArray.hpp"
  80 #include "utilities/macros.hpp"
  81 #include "utilities/ostream.hpp"
  82 
  83 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
  84 
  85 void ClassLoaderData::init_null_class_loader_data() {
  86   assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
  87   assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
  88 
  89   _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
  90   ClassLoaderDataGraph::_head = _the_null_class_loader_data;
  91   assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
  92 
  93   LogTarget(Trace, class, loader, data) lt;
  94   if (lt.is_enabled()) {
  95     ResourceMark rm;
  96     LogStream ls(lt);
  97     ls.print("create ");
  98     _the_null_class_loader_data->print_value_on(&ls);
  99     ls.cr();
 100   }
 101 }
 102 
 103 // Obtain and set the class loader's name within the ClassLoaderData so
 104 // it will be available for error messages, logging, JFR, etc.  The name
 105 // and klass are available after the class_loader oop is no longer alive,
 106 // during unloading.
 107 void ClassLoaderData::initialize_name(Handle class_loader) {
 108   ResourceMark rm;
 109 
 110   // Obtain the class loader's name.  If the class loader's name was not
 111   // explicitly set during construction, the CLD's _name field will be null.
 112   oop cl_name = java_lang_ClassLoader::name(class_loader());
 113   if (cl_name != NULL) {
 114     const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name);
 115 
 116     if (cl_instance_name != NULL && cl_instance_name[0] != '\0') {
 117       _name = SymbolTable::new_symbol(cl_instance_name);
 118     }
 119   }
 120 
 121   // Obtain the class loader's name and identity hash.  If the class loader's
 122   // name was not explicitly set during construction, the class loader's name and id
 123   // will be set to the qualified class name of the class loader along with its
 124   // identity hash.
 125   // If for some reason the ClassLoader's constructor has not been run, instead of
 126   // leaving the _name_and_id field null, fall back to the external qualified class
 127   // name.  Thus CLD's _name_and_id field should never have a null value.
 128   oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
 129   const char* cl_instance_name_and_id =
 130                   (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
 131                                              java_lang_String::as_utf8_string(cl_name_and_id);
 132   assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
 133   _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id);
 134 }
 135 
 136 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool has_class_mirror_holder) :
 137   _metaspace(NULL),
 138   _metaspace_lock(new Mutex(Mutex::nosafepoint-2, "MetaspaceAllocation_lock")),
 139   _unloading(false), _has_class_mirror_holder(has_class_mirror_holder),
 140   _modified_oops(true),
 141   // A non-strong hidden class loader data doesn't have anything to keep
 142   // it from being unloaded during parsing of the non-strong hidden class.
 143   // The null-class-loader should always be kept alive.
 144   _keep_alive((has_class_mirror_holder || h_class_loader.is_null()) ? 1 : 0),
 145   _claim(0),
 146   _handles(),
 147   _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
 148   _jmethod_ids(NULL),
 149   _deallocate_list(NULL),
 150   _next(NULL),
 151   _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) {
 152 
 153   if (!h_class_loader.is_null()) {
 154     _class_loader = _handles.add(h_class_loader());
 155     _class_loader_klass = h_class_loader->klass();
 156     initialize_name(h_class_loader);
 157   }
 158 
 159   if (!has_class_mirror_holder) {
 160     // The holder is initialized later for non-strong hidden classes,
 161     // and before calling anything that call class_loader().
 162     initialize_holder(h_class_loader);
 163 
 164     // A ClassLoaderData created solely for a non-strong hidden class should never
 165     // have a ModuleEntryTable or PackageEntryTable created for it.
 166     _packages = new PackageEntryTable();
 167     if (h_class_loader.is_null()) {
 168       // Create unnamed module for boot loader
 169       _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
 170     } else {
 171       // Create unnamed module for all other loaders
 172       _unnamed_module = ModuleEntry::create_unnamed_module(this);
 173     }
 174     _dictionary = create_dictionary();
 175   }
 176 
 177   NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
 178 
 179   JFR_ONLY(INIT_ID(this);)
 180 }
 181 
 182 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
 183   Chunk* c = _head;
 184   while (c != NULL) {
 185     Chunk* next = c->_next;
 186     delete c;
 187     c = next;
 188   }
 189 }
 190 
 191 OopHandle ClassLoaderData::ChunkedHandleList::add(oop o) {
 192   if (_head == NULL || _head->_size == Chunk::CAPACITY) {
 193     Chunk* next = new Chunk(_head);
 194     Atomic::release_store(&_head, next);
 195   }
 196   oop* handle = &_head->_data[_head->_size];
 197   NativeAccess<IS_DEST_UNINITIALIZED>::oop_store(handle, o);
 198   Atomic::release_store(&_head->_size, _head->_size + 1);
 199   return OopHandle(handle);
 200 }
 201 
 202 int ClassLoaderData::ChunkedHandleList::count() const {
 203   int count = 0;
 204   Chunk* chunk = _head;
 205   while (chunk != NULL) {
 206     count += chunk->_size;
 207     chunk = chunk->_next;
 208   }
 209   return count;
 210 }
 211 
 212 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
 213   for (juint i = 0; i < size; i++) {
 214     if (c->_data[i] != NULL) {
 215       f->do_oop(&c->_data[i]);
 216     }
 217   }
 218 }
 219 
 220 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
 221   Chunk* head = Atomic::load_acquire(&_head);
 222   if (head != NULL) {
 223     // Must be careful when reading size of head
 224     oops_do_chunk(f, head, Atomic::load_acquire(&head->_size));
 225     for (Chunk* c = head->_next; c != NULL; c = c->_next) {
 226       oops_do_chunk(f, c, c->_size);
 227     }
 228   }
 229 }
 230 
 231 class VerifyContainsOopClosure : public OopClosure {
 232   oop  _target;
 233   bool _found;
 234 
 235  public:
 236   VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
 237 
 238   void do_oop(oop* p) {
 239     if (p != NULL && NativeAccess<AS_NO_KEEPALIVE>::oop_load(p) == _target) {
 240       _found = true;
 241     }
 242   }
 243 
 244   void do_oop(narrowOop* p) {
 245     // The ChunkedHandleList should not contain any narrowOop
 246     ShouldNotReachHere();
 247   }
 248 
 249   bool found() const {
 250     return _found;
 251   }
 252 };
 253 
 254 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
 255   VerifyContainsOopClosure cl(p);
 256   oops_do(&cl);
 257   return cl.found();
 258 }
 259 
 260 #ifndef PRODUCT
 261 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
 262   Chunk* chunk = _head;
 263   while (chunk != NULL) {
 264     if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
 265       return true;
 266     }
 267     chunk = chunk->_next;
 268   }
 269   return false;
 270 }
 271 #endif // PRODUCT
 272 
 273 void ClassLoaderData::clear_claim(int claim) {
 274   for (;;) {
 275     int old_claim = Atomic::load(&_claim);
 276     if ((old_claim & claim) == 0) {
 277       return;
 278     }
 279     int new_claim = old_claim & ~claim;
 280     if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) {
 281       return;
 282     }
 283   }
 284 }
 285 
 286 #ifdef ASSERT
 287 void ClassLoaderData::verify_not_claimed(int claim) {
 288   assert((_claim & claim) == 0, "Found claim: %d bits in _claim: %d", claim, _claim);
 289 }
 290 #endif
 291 
 292 bool ClassLoaderData::try_claim(int claim) {
 293   for (;;) {
 294     int old_claim = Atomic::load(&_claim);
 295     if ((old_claim & claim) == claim) {
 296       return false;
 297     }
 298     int new_claim = old_claim | claim;
 299     if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) {
 300       return true;
 301     }
 302   }
 303 }
 304 
 305 // Non-strong hidden classes have their own ClassLoaderData that is marked to keep alive
 306 // while the class is being parsed, and if the class appears on the module fixup list.
 307 // Due to the uniqueness that no other class shares the hidden class' name or
 308 // ClassLoaderData, no other non-GC thread has knowledge of the hidden class while
 309 // it is being defined, therefore _keep_alive is not volatile or atomic.
 310 void ClassLoaderData::inc_keep_alive() {
 311   if (has_class_mirror_holder()) {
 312     assert(_keep_alive > 0, "Invalid keep alive increment count");
 313     _keep_alive++;
 314   }
 315 }
 316 
 317 void ClassLoaderData::dec_keep_alive() {
 318   if (has_class_mirror_holder()) {
 319     assert(_keep_alive > 0, "Invalid keep alive decrement count");
 320     _keep_alive--;
 321   }
 322 }
 323 
 324 void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) {
 325   if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) {
 326     return;
 327   }
 328 
 329   // Only clear modified_oops after the ClassLoaderData is claimed.
 330   if (clear_mod_oops) {
 331     clear_modified_oops();
 332   }
 333 
 334   _handles.oops_do(f);
 335 }
 336 
 337 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
 338   // Lock-free access requires load_acquire
 339   for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
 340     klass_closure->do_klass(k);
 341     assert(k != k->next_link(), "no loops!");
 342   }
 343 }
 344 
 345 void ClassLoaderData::classes_do(void f(Klass * const)) {
 346   // Lock-free access requires load_acquire
 347   for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
 348     f(k);
 349     assert(k != k->next_link(), "no loops!");
 350   }
 351 }
 352 
 353 void ClassLoaderData::methods_do(void f(Method*)) {
 354   // Lock-free access requires load_acquire
 355   for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
 356     if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
 357       InstanceKlass::cast(k)->methods_do(f);
 358     }
 359   }
 360 }
 361 
 362 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
 363   // To call this, one must have the MultiArray_lock held, but the _klasses list still has lock free reads.
 364   assert_locked_or_safepoint(MultiArray_lock);
 365 
 366   // Lock-free access requires load_acquire
 367   for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
 368     // Filter out InstanceKlasses (or their ObjArrayKlasses) that have not entered the
 369     // loaded state.
 370     if (k->is_instance_klass()) {
 371       if (!InstanceKlass::cast(k)->is_loaded()) {
 372         continue;
 373       }
 374     } else if (k->is_shared() && k->is_objArray_klass()) {
 375       Klass* bottom = ObjArrayKlass::cast(k)->bottom_klass();
 376       if (bottom->is_instance_klass() && !InstanceKlass::cast(bottom)->is_loaded()) {
 377         // This could happen if <bottom> is a shared class that has been restored
 378         // but is not yet marked as loaded. All archived array classes of the
 379         // bottom class are already restored and placed in the _klasses list.
 380         continue;
 381       }
 382     }
 383 
 384 #ifdef ASSERT
 385     oop m = k->java_mirror();
 386     assert(m != NULL, "NULL mirror");
 387     assert(m->is_a(vmClasses::Class_klass()), "invalid mirror");
 388 #endif
 389     klass_closure->do_klass(k);
 390   }
 391 }
 392 
 393 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
 394   // Lock-free access requires load_acquire
 395   for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
 396     if (k->is_instance_klass()) {
 397       f(InstanceKlass::cast(k));
 398     }
 399     assert(k != k->next_link(), "no loops!");
 400   }
 401 }
 402 
 403 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
 404   assert_locked_or_safepoint(Module_lock);
 405   if (_unnamed_module != NULL) {
 406     f(_unnamed_module);
 407   }
 408   if (_modules != NULL) {
 409     _modules->modules_do(f);
 410   }
 411 }
 412 
 413 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
 414   assert_locked_or_safepoint(Module_lock);
 415   if (_packages != NULL) {
 416     _packages->packages_do(f);
 417   }
 418 }
 419 
 420 void ClassLoaderData::record_dependency(const Klass* k) {
 421   assert(k != NULL, "invariant");
 422 
 423   ClassLoaderData * const from_cld = this;
 424   ClassLoaderData * const to_cld = k->class_loader_data();
 425 
 426   // Do not need to record dependency if the dependency is to a class whose
 427   // class loader data is never freed.  (i.e. the dependency's class loader
 428   // is one of the three builtin class loaders and the dependency's class
 429   // loader data has a ClassLoader holder, not a Class holder.)
 430   if (to_cld->is_permanent_class_loader_data()) {
 431     return;
 432   }
 433 
 434   oop to;
 435   if (to_cld->has_class_mirror_holder()) {
 436     // Just return if a non-strong hidden class class is attempting to record a dependency
 437     // to itself.  (Note that every non-strong hidden class has its own unique class
 438     // loader data.)
 439     if (to_cld == from_cld) {
 440       return;
 441     }
 442     // Hidden class dependencies are through the mirror.
 443     to = k->java_mirror();
 444   } else {
 445     to = to_cld->class_loader();
 446     oop from = from_cld->class_loader();
 447 
 448     // Just return if this dependency is to a class with the same or a parent
 449     // class_loader.
 450     if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {
 451       return; // this class loader is in the parent list, no need to add it.
 452     }
 453   }
 454 
 455   // It's a dependency we won't find through GC, add it.
 456   if (!_handles.contains(to)) {
 457     NOT_PRODUCT(Atomic::inc(&_dependency_count));
 458     LogTarget(Trace, class, loader, data) lt;
 459     if (lt.is_enabled()) {
 460       ResourceMark rm;
 461       LogStream ls(lt);
 462       ls.print("adding dependency from ");
 463       print_value_on(&ls);
 464       ls.print(" to ");
 465       to_cld->print_value_on(&ls);
 466       ls.cr();
 467     }
 468     Handle dependency(Thread::current(), to);
 469     add_handle(dependency);
 470     // Added a potentially young gen oop to the ClassLoaderData
 471     record_modified_oops();
 472   }
 473 }
 474 
 475 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
 476   {
 477     MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
 478     Klass* old_value = _klasses;
 479     k->set_next_link(old_value);
 480     // Link the new item into the list, making sure the linked class is stable
 481     // since the list can be walked without a lock
 482     Atomic::release_store(&_klasses, k);
 483     if (k->is_array_klass()) {
 484       ClassLoaderDataGraph::inc_array_classes(1);
 485     } else {
 486       ClassLoaderDataGraph::inc_instance_classes(1);
 487     }
 488   }
 489 
 490   if (publicize) {
 491     LogTarget(Trace, class, loader, data) lt;
 492     if (lt.is_enabled()) {
 493       ResourceMark rm;
 494       LogStream ls(lt);
 495       ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
 496       print_value_on(&ls);
 497       ls.cr();
 498     }
 499   }
 500 }
 501 
 502 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
 503   if (loader_or_mirror() != NULL) {
 504     assert(_holder.is_null(), "never replace holders");
 505     _holder = WeakHandle(Universe::vm_weak(), loader_or_mirror);
 506   }
 507 }
 508 
 509 // Remove a klass from the _klasses list for scratch_class during redefinition
 510 // or parsed class in the case of an error.
 511 void ClassLoaderData::remove_class(Klass* scratch_class) {
 512   assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
 513 
 514   // Adjust global class iterator.
 515   ClassLoaderDataGraph::adjust_saved_class(scratch_class);
 516 
 517   Klass* prev = NULL;
 518   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 519     if (k == scratch_class) {
 520       if (prev == NULL) {
 521         _klasses = k->next_link();
 522       } else {
 523         Klass* next = k->next_link();
 524         prev->set_next_link(next);
 525       }
 526 
 527       if (k->is_array_klass()) {
 528         ClassLoaderDataGraph::dec_array_classes(1);
 529       } else {
 530         ClassLoaderDataGraph::dec_instance_classes(1);
 531       }
 532 
 533       return;
 534     }
 535     prev = k;
 536     assert(k != k->next_link(), "no loops!");
 537   }
 538   ShouldNotReachHere();   // should have found this class!!
 539 }
 540 
 541 void ClassLoaderData::unload() {
 542   _unloading = true;
 543 
 544   LogTarget(Trace, class, loader, data) lt;
 545   if (lt.is_enabled()) {
 546     ResourceMark rm;
 547     LogStream ls(lt);
 548     ls.print("unload");
 549     print_value_on(&ls);
 550     ls.cr();
 551   }
 552 
 553   // Some items on the _deallocate_list need to free their C heap structures
 554   // if they are not already on the _klasses list.
 555   free_deallocate_list_C_heap_structures();
 556 
 557   // Clean up class dependencies and tell serviceability tools
 558   // these classes are unloading.  Must be called
 559   // after erroneous classes are released.
 560   classes_do(InstanceKlass::unload_class);
 561 
 562   // Method::clear_jmethod_ids only sets the jmethod_ids to NULL without
 563   // releasing the memory for related JNIMethodBlocks and JNIMethodBlockNodes.
 564   // This is done intentionally because native code (e.g. JVMTI agent) holding
 565   // jmethod_ids may access them after the associated classes and class loader
 566   // are unloaded. The Java Native Interface Specification says "method ID
 567   // does not prevent the VM from unloading the class from which the ID has
 568   // been derived. After the class is unloaded, the method or field ID becomes
 569   // invalid". In real world usages, the native code may rely on jmethod_ids
 570   // being NULL after class unloading. Hence, it is unsafe to free the memory
 571   // from the VM side without knowing when native code is going to stop using
 572   // them.
 573   if (_jmethod_ids != NULL) {
 574     Method::clear_jmethod_ids(this);
 575   }
 576 
 577   // Clean up global class iterator for compiler
 578   ClassLoaderDataGraph::adjust_saved_class(this);
 579 }
 580 
 581 ModuleEntryTable* ClassLoaderData::modules() {
 582   // Lazily create the module entry table at first request.
 583   // Lock-free access requires load_acquire.
 584   ModuleEntryTable* modules = Atomic::load_acquire(&_modules);
 585   if (modules == NULL) {
 586     MutexLocker m1(Module_lock);
 587     // Check if _modules got allocated while we were waiting for this lock.
 588     if ((modules = _modules) == NULL) {
 589       modules = new ModuleEntryTable();
 590 
 591       {
 592         MutexLocker m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
 593         // Ensure _modules is stable, since it is examined without a lock
 594         Atomic::release_store(&_modules, modules);
 595       }
 596     }
 597   }
 598   return modules;
 599 }
 600 
 601 const int _boot_loader_dictionary_size    = 1009;
 602 const int _default_loader_dictionary_size = 107;
 603 
 604 Dictionary* ClassLoaderData::create_dictionary() {
 605   assert(!has_class_mirror_holder(), "class mirror holder cld does not have a dictionary");
 606   int size;
 607   if (_the_null_class_loader_data == NULL) {
 608     size = _boot_loader_dictionary_size;
 609   } else if (class_loader()->is_a(vmClasses::reflect_DelegatingClassLoader_klass())) {
 610     size = 1;  // there's only one class in relection class loader and no initiated classes
 611   } else if (is_system_class_loader_data()) {
 612     size = _boot_loader_dictionary_size;
 613   } else {
 614     size = _default_loader_dictionary_size;
 615   }
 616   return new Dictionary(this, size);
 617 }
 618 
 619 // Tell the GC to keep this klass alive. Needed while iterating ClassLoaderDataGraph,
 620 // and any runtime code that uses klasses.
 621 oop ClassLoaderData::holder() const {
 622   // A klass that was previously considered dead can be looked up in the
 623   // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
 624   // or a reachable object making it alive again. The SATB part of G1 needs
 625   // to get notified about this potential resurrection, otherwise the marking
 626   // might not find the object.
 627   if (!_holder.is_null()) {  // NULL class_loader
 628     return _holder.resolve();
 629   } else {
 630     return NULL;
 631   }
 632 }
 633 
 634 // Let the GC read the holder without keeping it alive.
 635 oop ClassLoaderData::holder_no_keepalive() const {
 636   if (!_holder.is_null()) {  // NULL class_loader
 637     return _holder.peek();
 638   } else {
 639     return NULL;
 640   }
 641 }
 642 
 643 // Unloading support
 644 bool ClassLoaderData::is_alive() const {
 645   bool alive = keep_alive()         // null class loader and incomplete non-strong hidden class.
 646       || (_holder.peek() != NULL);  // and not cleaned by the GC weak handle processing.
 647 
 648   return alive;
 649 }
 650 
 651 class ReleaseKlassClosure: public KlassClosure {
 652 private:
 653   size_t  _instance_class_released;
 654   size_t  _array_class_released;
 655 public:
 656   ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
 657 
 658   size_t instance_class_released() const { return _instance_class_released; }
 659   size_t array_class_released()    const { return _array_class_released;    }
 660 
 661   void do_klass(Klass* k) {
 662     if (k->is_array_klass()) {
 663       _array_class_released ++;
 664     } else {
 665       assert(k->is_instance_klass(), "Must be");
 666       _instance_class_released ++;
 667     }
 668     k->release_C_heap_structures();
 669   }
 670 };
 671 
 672 ClassLoaderData::~ClassLoaderData() {
 673   // Release C heap structures for all the classes.
 674   ReleaseKlassClosure cl;
 675   classes_do(&cl);
 676 
 677   ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
 678   ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
 679 
 680   // Release the WeakHandle
 681   _holder.release(Universe::vm_weak());
 682 
 683   // Release C heap allocated hashtable for all the packages.
 684   if (_packages != NULL) {
 685     // Destroy the table itself
 686     delete _packages;
 687     _packages = NULL;
 688   }
 689 
 690   // Release C heap allocated hashtable for all the modules.
 691   if (_modules != NULL) {
 692     // Destroy the table itself
 693     delete _modules;
 694     _modules = NULL;
 695   }
 696 
 697   // Release C heap allocated hashtable for the dictionary
 698   if (_dictionary != NULL) {
 699     // Destroy the table itself
 700     delete _dictionary;
 701     _dictionary = NULL;
 702   }
 703 
 704   if (_unnamed_module != NULL) {
 705     delete _unnamed_module;
 706     _unnamed_module = NULL;
 707   }
 708 
 709   // release the metaspace
 710   ClassLoaderMetaspace *m = _metaspace;
 711   if (m != NULL) {
 712     _metaspace = NULL;
 713     delete m;
 714   }
 715 
 716   // Delete lock
 717   delete _metaspace_lock;
 718 
 719   // Delete free list
 720   if (_deallocate_list != NULL) {
 721     delete _deallocate_list;
 722   }
 723 
 724   // Decrement refcounts of Symbols if created.
 725   if (_name != NULL) {
 726     _name->decrement_refcount();
 727   }
 728   if (_name_and_id != NULL) {
 729     _name_and_id->decrement_refcount();
 730   }
 731 }
 732 
 733 // Returns true if this class loader data is for the app class loader
 734 // or a user defined system class loader.  (Note that the class loader
 735 // data may have a Class holder.)
 736 bool ClassLoaderData::is_system_class_loader_data() const {
 737   return SystemDictionary::is_system_class_loader(class_loader());
 738 }
 739 
 740 // Returns true if this class loader data is for the platform class loader.
 741 // (Note that the class loader data may have a Class holder.)
 742 bool ClassLoaderData::is_platform_class_loader_data() const {
 743   return SystemDictionary::is_platform_class_loader(class_loader());
 744 }
 745 
 746 // Returns true if the class loader for this class loader data is one of
 747 // the 3 builtin (boot application/system or platform) class loaders,
 748 // including a user-defined system class loader.  Note that if the class
 749 // loader data is for a non-strong hidden class then it may
 750 // get freed by a GC even if its class loader is one of these loaders.
 751 bool ClassLoaderData::is_builtin_class_loader_data() const {
 752   return (is_boot_class_loader_data() ||
 753           SystemDictionary::is_system_class_loader(class_loader()) ||
 754           SystemDictionary::is_platform_class_loader(class_loader()));
 755 }
 756 
 757 // Returns true if this class loader data is a class loader data
 758 // that is not ever freed by a GC.  It must be the CLD for one of the builtin
 759 // class loaders and not the CLD for a non-strong hidden class.
 760 bool ClassLoaderData::is_permanent_class_loader_data() const {
 761   return is_builtin_class_loader_data() && !has_class_mirror_holder();
 762 }
 763 
 764 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
 765   // If the metaspace has not been allocated, create a new one.  Might want
 766   // to create smaller arena for Reflection class loaders also.
 767   // The reason for the delayed allocation is because some class loaders are
 768   // simply for delegating with no metadata of their own.
 769   // Lock-free access requires load_acquire.
 770   ClassLoaderMetaspace* metaspace = Atomic::load_acquire(&_metaspace);
 771   if (metaspace == NULL) {
 772     MutexLocker ml(_metaspace_lock,  Mutex::_no_safepoint_check_flag);
 773     // Check if _metaspace got allocated while we were waiting for this lock.
 774     if ((metaspace = _metaspace) == NULL) {
 775       if (this == the_null_class_loader_data()) {
 776         assert (class_loader() == NULL, "Must be");
 777         metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
 778       } else if (has_class_mirror_holder()) {
 779         metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ClassMirrorHolderMetaspaceType);
 780       } else if (class_loader()->is_a(vmClasses::reflect_DelegatingClassLoader_klass())) {
 781         metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
 782       } else {
 783         metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
 784       }
 785       // Ensure _metaspace is stable, since it is examined without a lock
 786       Atomic::release_store(&_metaspace, metaspace);
 787     }
 788   }
 789   return metaspace;
 790 }
 791 
 792 OopHandle ClassLoaderData::add_handle(Handle h) {
 793   MutexLocker ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 794   record_modified_oops();
 795   return _handles.add(h());
 796 }
 797 
 798 void ClassLoaderData::remove_handle(OopHandle h) {
 799   assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
 800   oop* ptr = h.ptr_raw();
 801   if (ptr != NULL) {
 802     assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
 803     NativeAccess<>::oop_store(ptr, oop(NULL));
 804   }
 805 }
 806 
 807 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
 808   MutexLocker ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 809   if (dest.resolve() != NULL) {
 810     return;
 811   } else {
 812     record_modified_oops();
 813     dest = _handles.add(h());
 814   }
 815 }
 816 
 817 // Add this metadata pointer to be freed when it's safe.  This is only during
 818 // a safepoint which checks if handles point to this metadata field.
 819 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
 820   // Metadata in shared region isn't deleted.
 821   if (!m->is_shared()) {
 822     MutexLocker ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 823     if (_deallocate_list == NULL) {
 824       _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, mtClass);
 825     }
 826     _deallocate_list->append_if_missing(m);
 827     log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
 828     ClassLoaderDataGraph::set_should_clean_deallocate_lists();
 829   }
 830 }
 831 
 832 // Deallocate free metadata on the free list.  How useful the PermGen was!
 833 void ClassLoaderData::free_deallocate_list() {
 834   // This must be called at a safepoint because it depends on metadata walking at
 835   // safepoint cleanup time.
 836   assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
 837   assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
 838   if (_deallocate_list == NULL) {
 839     return;
 840   }
 841   // Go backwards because this removes entries that are freed.
 842   for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
 843     Metadata* m = _deallocate_list->at(i);
 844     if (!m->on_stack()) {
 845       _deallocate_list->remove_at(i);
 846       // There are only three types of metadata that we deallocate directly.
 847       // Cast them so they can be used by the template function.
 848       if (m->is_method()) {
 849         MetadataFactory::free_metadata(this, (Method*)m);
 850       } else if (m->is_constantPool()) {
 851         MetadataFactory::free_metadata(this, (ConstantPool*)m);
 852       } else if (m->is_klass()) {
 853         MetadataFactory::free_metadata(this, (InstanceKlass*)m);
 854       } else {
 855         ShouldNotReachHere();
 856       }
 857     } else {
 858       // Metadata is alive.
 859       // If scratch_class is on stack then it shouldn't be on this list!
 860       assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
 861              "scratch classes on this list should be dead");
 862       // Also should assert that other metadata on the list was found in handles.
 863       // Some cleaning remains.
 864       ClassLoaderDataGraph::set_should_clean_deallocate_lists();
 865     }
 866   }
 867 }
 868 
 869 // This is distinct from free_deallocate_list.  For class loader data that are
 870 // unloading, this frees the C heap memory for items on the list, and unlinks
 871 // scratch or error classes so that unloading events aren't triggered for these
 872 // classes. The metadata is removed with the unloading metaspace.
 873 // There isn't C heap memory allocated for methods, so nothing is done for them.
 874 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
 875   assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
 876   assert(is_unloading(), "only called for ClassLoaderData that are unloading");
 877   if (_deallocate_list == NULL) {
 878     return;
 879   }
 880   // Go backwards because this removes entries that are freed.
 881   for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
 882     Metadata* m = _deallocate_list->at(i);
 883     _deallocate_list->remove_at(i);
 884     if (m->is_constantPool()) {
 885       ((ConstantPool*)m)->release_C_heap_structures();
 886     } else if (m->is_klass()) {
 887       InstanceKlass* ik = (InstanceKlass*)m;
 888       // also releases ik->constants() C heap memory
 889       ik->release_C_heap_structures();
 890       // Remove the class so unloading events aren't triggered for
 891       // this class (scratch or error class) in do_unloading().
 892       remove_class(ik);
 893       // But still have to remove it from the dumptime_table.
 894       SystemDictionaryShared::handle_class_unloading(ik);
 895     }
 896   }
 897 }
 898 
 899 // Caller needs ResourceMark
 900 // If the class loader's _name has not been explicitly set, the class loader's
 901 // qualified class name is returned.
 902 const char* ClassLoaderData::loader_name() const {
 903    if (_class_loader_klass == NULL) {
 904      return BOOTSTRAP_LOADER_NAME;
 905    } else if (_name != NULL) {
 906      return _name->as_C_string();
 907    } else {
 908      return _class_loader_klass->external_name();
 909    }
 910 }
 911 
 912 // Caller needs ResourceMark
 913 // Format of the _name_and_id is as follows:
 914 //   If the defining loader has a name explicitly set then '<loader-name>' @<id>
 915 //   If the defining loader has no name then <qualified-class-name> @<id>
 916 //   If built-in loader, then omit '@<id>' as there is only one instance.
 917 const char* ClassLoaderData::loader_name_and_id() const {
 918   if (_class_loader_klass == NULL) {
 919     return "'" BOOTSTRAP_LOADER_NAME "'";
 920   } else if (_name_and_id != NULL) {
 921     return _name_and_id->as_C_string();
 922   } else {
 923     // May be called in a race before _name_and_id is initialized.
 924     return _class_loader_klass->external_name();
 925   }
 926 }
 927 
 928 void ClassLoaderData::print_value_on(outputStream* out) const {
 929   if (!is_unloading() && class_loader() != NULL) {
 930     out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
 931     class_loader()->print_value_on(out);  // includes loader_name_and_id() and address of class loader instance
 932   } else {
 933     // loader data: 0xsomeaddr of 'bootstrap'
 934     out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
 935   }
 936   if (_has_class_mirror_holder) {
 937     out->print(" has a class holder");
 938   }
 939 }
 940 
 941 void ClassLoaderData::print_value() const { print_value_on(tty); }
 942 
 943 #ifndef PRODUCT
 944 class PrintKlassClosure: public KlassClosure {
 945   outputStream* _out;
 946 public:
 947   PrintKlassClosure(outputStream* out): _out(out) { }
 948 
 949   void do_klass(Klass* k) {
 950     ResourceMark rm;
 951     _out->print("%s,", k->external_name());
 952   }
 953 };
 954 
 955 void ClassLoaderData::print_on(outputStream* out) const {
 956   ResourceMark rm;
 957   out->print_cr("ClassLoaderData(" INTPTR_FORMAT ")", p2i(this));
 958   out->print_cr(" - name                %s", loader_name_and_id());
 959   if (!_holder.is_null()) {
 960     out->print   (" - holder              ");
 961     _holder.print_on(out);
 962     out->print_cr("");
 963   }
 964   out->print_cr(" - class loader        " INTPTR_FORMAT, p2i(_class_loader.ptr_raw()));
 965   out->print_cr(" - metaspace           " INTPTR_FORMAT, p2i(_metaspace));
 966   out->print_cr(" - unloading           %s", _unloading ? "true" : "false");
 967   out->print_cr(" - class mirror holder %s", _has_class_mirror_holder ? "true" : "false");
 968   out->print_cr(" - modified oops       %s", _modified_oops ? "true" : "false");
 969   out->print_cr(" - keep alive          %d", _keep_alive);
 970   out->print   (" - claim               ");
 971   switch(_claim) {
 972     case _claim_none:                       out->print_cr("none"); break;
 973     case _claim_finalizable:                out->print_cr("finalizable"); break;
 974     case _claim_strong:                     out->print_cr("strong"); break;
 975     case _claim_other:                      out->print_cr("other"); break;
 976     case _claim_other | _claim_finalizable: out->print_cr("other and finalizable"); break;
 977     case _claim_other | _claim_strong:      out->print_cr("other and strong"); break;
 978     default:                                ShouldNotReachHere();
 979   }
 980   out->print_cr(" - handles             %d", _handles.count());
 981   out->print_cr(" - dependency count    %d", _dependency_count);
 982   out->print   (" - klasses             { ");
 983   if (Verbose) {
 984     PrintKlassClosure closure(out);
 985     ((ClassLoaderData*)this)->classes_do(&closure);
 986   } else {
 987      out->print("...");
 988   }
 989   out->print_cr(" }");
 990   out->print_cr(" - packages            " INTPTR_FORMAT, p2i(_packages));
 991   out->print_cr(" - module              " INTPTR_FORMAT, p2i(_modules));
 992   out->print_cr(" - unnamed module      " INTPTR_FORMAT, p2i(_unnamed_module));
 993   if (_dictionary != nullptr) {
 994     out->print   (" - dictionary          " INTPTR_FORMAT " ", p2i(_dictionary));
 995     _dictionary->print_size(out);
 996   } else {
 997     out->print_cr(" - dictionary          " INTPTR_FORMAT, p2i(_dictionary));
 998   }
 999   if (_jmethod_ids != NULL) {
1000     out->print   (" - jmethod count       ");
1001     Method::print_jmethod_ids_count(this, out);
1002     out->print_cr("");
1003   }
1004   out->print_cr(" - deallocate list     " INTPTR_FORMAT, p2i(_deallocate_list));
1005   out->print_cr(" - next CLD            " INTPTR_FORMAT, p2i(_next));
1006 }
1007 #endif // PRODUCT
1008 
1009 void ClassLoaderData::print() const { print_on(tty); }
1010 
1011 void ClassLoaderData::verify() {
1012   assert_locked_or_safepoint(_metaspace_lock);
1013   oop cl = class_loader();
1014 
1015   guarantee(this == class_loader_data(cl) || has_class_mirror_holder(), "Must be the same");
1016   guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || has_class_mirror_holder(), "must be");
1017 
1018   // Verify the integrity of the allocated space.
1019 #ifdef ASSERT
1020   if (metaspace_or_null() != NULL) {
1021     metaspace_or_null()->verify();
1022   }
1023 #endif
1024 
1025   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
1026     guarantee(k->class_loader_data() == this, "Must be the same");
1027     k->verify();
1028     assert(k != k->next_link(), "no loops!");
1029   }
1030 
1031   if (_modules != NULL) {
1032     _modules->verify();
1033   }
1034 }
1035 
1036 bool ClassLoaderData::contains_klass(Klass* klass) {
1037   // Lock-free access requires load_acquire
1038   for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
1039     if (k == klass) return true;
1040   }
1041   return false;
1042 }