1 /*
   2  * Copyright (c) 2012, 2016, 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 // 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 // extension, 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.hpp"
  51 #include "classfile/classLoaderData.inline.hpp"
  52 #include "classfile/javaClasses.hpp"
  53 #include "classfile/metadataOnStackMark.hpp"
  54 #include "classfile/systemDictionary.hpp"
  55 #include "code/codeCache.hpp"
  56 #include "gc/shared/gcLocker.hpp"
  57 #include "logging/log.hpp"
  58 #include "memory/metadataFactory.hpp"
  59 #include "memory/metaspaceShared.hpp"
  60 #include "memory/oopFactory.hpp"

  61 #include "oops/objArrayOop.inline.hpp"
  62 #include "oops/oop.inline.hpp"
  63 #include "runtime/atomic.inline.hpp"
  64 #include "runtime/javaCalls.hpp"
  65 #include "runtime/jniHandles.hpp"
  66 #include "runtime/mutex.hpp"
  67 #include "runtime/safepoint.hpp"
  68 #include "runtime/synchronizer.hpp"
  69 #include "utilities/growableArray.hpp"
  70 #include "utilities/macros.hpp"
  71 #include "utilities/ostream.hpp"
  72 #if INCLUDE_TRACE
  73 #include "trace/tracing.hpp"
  74 #endif
  75 
  76 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
  77 
  78 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
  79   _class_loader(h_class_loader()),
  80   _is_anonymous(is_anonymous),
  81   // An anonymous class loader data doesn't have anything to keep
  82   // it from being unloaded during parsing of the anonymous class.
  83   // The null-class-loader should always be kept alive.
  84   _keep_alive(is_anonymous || h_class_loader.is_null()),
  85   _metaspace(NULL), _unloading(false), _klasses(NULL),
  86   _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
  87   _next(NULL), _dependencies(dependencies), _shared_class_loader_id(-1),
  88   _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
  89                             Monitor::_safepoint_check_never)) {
  90     // empty
  91 }
  92 
  93 void ClassLoaderData::init_dependencies(TRAPS) {
  94   assert(!Universe::is_fully_initialized(), "should only be called when initializing");
  95   assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
  96   _dependencies.init(CHECK);
  97 }
  98 
  99 void ClassLoaderData::Dependencies::init(TRAPS) {
 100   // Create empty dependencies array to add to. CMS requires this to be
 101   // an oop so that it can track additions via card marks.  We think.
 102   _list_head = oopFactory::new_objectArray(2, CHECK);
 103 }
 104 
 105 bool ClassLoaderData::claim() {
 106   if (_claimed == 1) {
 107     return false;
 108   }
 109 
 110   return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
 111 }
 112 
 113 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
 114   if (must_claim && !claim()) {
 115     return;
 116   }
 117 
 118   f->do_oop(&_class_loader);
 119   _dependencies.oops_do(f);
 120   _handles->oops_do(f);
 121   if (klass_closure != NULL) {
 122     classes_do(klass_closure);
 123   }
 124 }
 125 
 126 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
 127   f->do_oop((oop*)&_list_head);
 128 }
 129 
 130 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
 131   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 132     klass_closure->do_klass(k);
 133     assert(k != k->next_link(), "no loops!");
 134   }
 135 }
 136 
 137 void ClassLoaderData::classes_do(void f(Klass * const)) {
 138   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 139     f(k);
 140   }
 141 }
 142 
 143 void ClassLoaderData::methods_do(void f(Method*)) {
 144   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 145     if (k->is_instance_klass()) {
 146       InstanceKlass::cast(k)->methods_do(f);
 147     }
 148   }
 149 }
 150 
 151 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
 152   // Lock to avoid classes being modified/added/removed during iteration
 153   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 154   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 155     // Do not filter ArrayKlass oops here...
 156     if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
 157       klass_closure->do_klass(k);
 158     }
 159   }
 160 }
 161 
 162 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
 163   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 164     if (k->is_instance_klass()) {
 165       f(InstanceKlass::cast(k));
 166     }
 167     assert(k != k->next_link(), "no loops!");
 168   }
 169 }
 170 
 171 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
 172   assert(k != NULL, "invariant");
 173 
 174   ClassLoaderData * const from_cld = this;
 175   ClassLoaderData * const to_cld = k->class_loader_data();
 176 
 177   // Dependency to the null class loader data doesn't need to be recorded
 178   // because the null class loader data never goes away.
 179   if (to_cld->is_the_null_class_loader_data()) {
 180     return;
 181   }
 182 
 183   oop to;
 184   if (to_cld->is_anonymous()) {
 185     // Anonymous class dependencies are through the mirror.
 186     to = k->java_mirror();
 187   } else {
 188     to = to_cld->class_loader();
 189 
 190     // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
 191     // we still have to add it.  The class_loader won't keep from_cld alive.
 192     if (!from_cld->is_anonymous()) {
 193       // Check that this dependency isn't from the same or parent class_loader
 194       oop from = from_cld->class_loader();
 195 
 196       oop curr = from;
 197       while (curr != NULL) {
 198         if (curr == to) {
 199           return; // this class loader is in the parent list, no need to add it.
 200         }
 201         curr = java_lang_ClassLoader::parent(curr);
 202       }
 203     }
 204   }
 205 
 206   // It's a dependency we won't find through GC, add it. This is relatively rare
 207   // Must handle over GC point.
 208   Handle dependency(THREAD, to);
 209   from_cld->_dependencies.add(dependency, CHECK);
 210 }
 211 
 212 
 213 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
 214   // Check first if this dependency is already in the list.
 215   // Save a pointer to the last to add to under the lock.
 216   objArrayOop ok = _list_head;
 217   objArrayOop last = NULL;
 218   while (ok != NULL) {
 219     last = ok;
 220     if (ok->obj_at(0) == dependency()) {
 221       // Don't need to add it
 222       return;
 223     }
 224     ok = (objArrayOop)ok->obj_at(1);
 225   }
 226 
 227   // Must handle over GC points
 228   assert (last != NULL, "dependencies should be initialized");
 229   objArrayHandle last_handle(THREAD, last);
 230 
 231   // Create a new dependency node with fields for (class_loader or mirror, next)
 232   objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
 233   deps->obj_at_put(0, dependency());
 234 
 235   // Must handle over GC points
 236   objArrayHandle new_dependency(THREAD, deps);
 237 
 238   // Add the dependency under lock
 239   locked_add(last_handle, new_dependency, THREAD);
 240 }
 241 
 242 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
 243                                                objArrayHandle new_dependency,
 244                                                Thread* THREAD) {
 245 
 246   // Have to lock and put the new dependency on the end of the dependency
 247   // array so the card mark for CMS sees that this dependency is new.
 248   // Can probably do this lock free with some effort.
 249   ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
 250 
 251   oop loader_or_mirror = new_dependency->obj_at(0);
 252 
 253   // Since the dependencies are only added, add to the end.
 254   objArrayOop end = last_handle();
 255   objArrayOop last = NULL;
 256   while (end != NULL) {
 257     last = end;
 258     // check again if another thread added it to the end.
 259     if (end->obj_at(0) == loader_or_mirror) {
 260       // Don't need to add it
 261       return;
 262     }
 263     end = (objArrayOop)end->obj_at(1);
 264   }
 265   assert (last != NULL, "dependencies should be initialized");
 266   // fill in the first element with the oop in new_dependency.
 267   if (last->obj_at(0) == NULL) {
 268     last->obj_at_put(0, new_dependency->obj_at(0));
 269   } else {
 270     last->obj_at_put(1, new_dependency());
 271   }
 272 }
 273 
 274 void ClassLoaderDataGraph::clear_claimed_marks() {
 275   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
 276     cld->clear_claimed();
 277   }
 278 }
 279 
 280 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
 281   {
 282     MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
 283     Klass* old_value = _klasses;
 284     k->set_next_link(old_value);
 285     // Make sure linked class is stable, since the class list is walked without a lock
 286     OrderAccess::storestore();
 287     // link the new item into the list
 288     _klasses = k;
 289   }
 290 
 291   if (publicize && k->class_loader_data() != NULL) {
 292     ResourceMark rm;
 293     log_trace(classloaderdata)("Adding k: " PTR_FORMAT " %s to CLD: "
 294                   PTR_FORMAT " loader: " PTR_FORMAT " %s",
 295                   p2i(k),
 296                   k->external_name(),
 297                   p2i(k->class_loader_data()),
 298                   p2i((void *)k->class_loader()),
 299                   loader_name());
 300   }
 301 }
 302 
 303 // This is called by InstanceKlass::deallocate_contents() to remove the
 304 // scratch_class for redefine classes.  We need a lock because there it may not
 305 // be called at a safepoint if there's an error.
 306 void ClassLoaderData::remove_class(Klass* scratch_class) {
 307   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 308   Klass* prev = NULL;
 309   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 310     if (k == scratch_class) {
 311       if (prev == NULL) {
 312         _klasses = k->next_link();
 313       } else {
 314         Klass* next = k->next_link();
 315         prev->set_next_link(next);
 316       }
 317       return;
 318     }
 319     prev = k;
 320     assert(k != k->next_link(), "no loops!");
 321   }
 322   ShouldNotReachHere();   // should have found this class!!
 323 }
 324 
 325 void ClassLoaderData::unload() {
 326   _unloading = true;
 327 
 328   // Tell serviceability tools these classes are unloading
 329   classes_do(InstanceKlass::notify_unload_class);
 330 
 331   if (log_is_enabled(Debug, classloaderdata)) {
 332     ResourceMark rm;
 333     outputStream* log = LogHandle(classloaderdata)::debug_stream();
 334     log->print(": unload loader data " INTPTR_FORMAT, p2i(this));
 335     log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
 336                loader_name());
 337     if (is_anonymous()) {
 338       log->print(" for anonymous class  " INTPTR_FORMAT " ", p2i(_klasses));
 339     }
 340     log->cr();
 341   }
 342 }
 343 
 344 oop ClassLoaderData::keep_alive_object() const {
 345   assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
 346   return is_anonymous() ? _klasses->java_mirror() : class_loader();
 347 }
 348 
 349 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
 350   bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
 351       || is_alive_closure->do_object_b(keep_alive_object());
 352 
 353   return alive;
 354 }
 355 
 356 
 357 ClassLoaderData::~ClassLoaderData() {
 358   // Release C heap structures for all the classes.
 359   classes_do(InstanceKlass::release_C_heap_structures);
 360 
 361   Metaspace *m = _metaspace;
 362   if (m != NULL) {
 363     _metaspace = NULL;
 364     // release the metaspace
 365     delete m;
 366     // release the handles
 367     if (_handles != NULL) {
 368       JNIHandleBlock::release_block(_handles);
 369       _handles = NULL;
 370     }
 371   }
 372 
 373   // Clear all the JNI handles for methods
 374   // These aren't deallocated and are going to look like a leak, but that's
 375   // needed because we can't really get rid of jmethodIDs because we don't
 376   // know when native code is going to stop using them.  The spec says that
 377   // they're "invalid" but existing programs likely rely on their being
 378   // NULL after class unloading.
 379   if (_jmethod_ids != NULL) {
 380     Method::clear_jmethod_ids(this);
 381   }
 382   // Delete lock
 383   delete _metaspace_lock;
 384 
 385   // Delete free list
 386   if (_deallocate_list != NULL) {
 387     delete _deallocate_list;
 388   }
 389 }
 390 
 391 /**
 392  * Returns true if this class loader data is for the extension class loader.
 393  */
 394 bool ClassLoaderData::is_ext_class_loader_data() const {
 395   return SystemDictionary::is_ext_class_loader(class_loader());
 396 }
 397 
 398 Metaspace* ClassLoaderData::metaspace_non_null() {
 399   assert(!DumpSharedSpaces, "wrong metaspace!");
 400   // If the metaspace has not been allocated, create a new one.  Might want
 401   // to create smaller arena for Reflection class loaders also.
 402   // The reason for the delayed allocation is because some class loaders are
 403   // simply for delegating with no metadata of their own.
 404   if (_metaspace == NULL) {
 405     MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 406     // Check again if metaspace has been allocated while we were getting this lock.
 407     if (_metaspace != NULL) {
 408       return _metaspace;
 409     }
 410     if (this == the_null_class_loader_data()) {
 411       assert (class_loader() == NULL, "Must be");
 412       set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
 413     } else if (is_anonymous()) {
 414       if (class_loader() != NULL) {
 415         log_trace(classloaderdata)("is_anonymous: %s", class_loader()->klass()->internal_name());
 416       }
 417       set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
 418     } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
 419       if (class_loader() != NULL) {
 420         log_trace(classloaderdata)("is_reflection: %s", class_loader()->klass()->internal_name());
 421       }
 422       set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
 423     } else {
 424       set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
 425     }
 426   }
 427   return _metaspace;
 428 }
 429 
 430 JNIHandleBlock* ClassLoaderData::handles() const           { return _handles; }
 431 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
 432 
 433 jobject ClassLoaderData::add_handle(Handle h) {
 434   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 435   if (handles() == NULL) {
 436     set_handles(JNIHandleBlock::allocate_block());
 437   }
 438   return handles()->allocate_handle(h());
 439 }
 440 
 441 // Add this metadata pointer to be freed when it's safe.  This is only during
 442 // class unloading because Handles might point to this metadata field.
 443 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
 444   // Metadata in shared region isn't deleted.
 445   if (!m->is_shared()) {
 446     MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 447     if (_deallocate_list == NULL) {
 448       _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
 449     }
 450     _deallocate_list->append_if_missing(m);
 451   }
 452 }
 453 
 454 // Deallocate free metadata on the free list.  How useful the PermGen was!
 455 void ClassLoaderData::free_deallocate_list() {
 456   // Don't need lock, at safepoint
 457   assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
 458   if (_deallocate_list == NULL) {
 459     return;
 460   }
 461   // Go backwards because this removes entries that are freed.
 462   for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
 463     Metadata* m = _deallocate_list->at(i);
 464     if (!m->on_stack()) {
 465       _deallocate_list->remove_at(i);
 466       // There are only three types of metadata that we deallocate directly.
 467       // Cast them so they can be used by the template function.
 468       if (m->is_method()) {
 469         MetadataFactory::free_metadata(this, (Method*)m);
 470       } else if (m->is_constantPool()) {
 471         MetadataFactory::free_metadata(this, (ConstantPool*)m);
 472       } else if (m->is_klass()) {
 473         MetadataFactory::free_metadata(this, (InstanceKlass*)m);
 474       } else {
 475         ShouldNotReachHere();
 476       }
 477     } else {
 478       // Metadata is alive.
 479       // If scratch_class is on stack then it shouldn't be on this list!
 480       assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
 481              "scratch classes on this list should be dead");
 482       // Also should assert that other metadata on the list was found in handles.
 483     }
 484   }
 485 }
 486 
 487 // These anonymous class loaders are to contain classes used for JSR292
 488 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
 489   // Add a new class loader data to the graph.
 490   return ClassLoaderDataGraph::add(loader, true, THREAD);
 491 }
 492 
 493 const char* ClassLoaderData::loader_name() {
 494   // Handles null class loader
 495   return SystemDictionary::loader_name(class_loader());
 496 }
 497 
 498 #ifndef PRODUCT
 499 // Define to dump klasses
 500 #undef CLD_DUMP_KLASSES
 501 
 502 void ClassLoaderData::dump(outputStream * const out) {
 503   ResourceMark rm;
 504   out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
 505       p2i(this), p2i((void *)class_loader()),
 506       p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
 507   if (claimed()) out->print(" claimed ");
 508   if (is_unloading()) out->print(" unloading ");
 509   out->print(" handles " INTPTR_FORMAT, p2i(handles()));
 510   out->cr();
 511   if (metaspace_or_null() != NULL) {
 512     out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
 513     metaspace_or_null()->dump(out);
 514   } else {
 515     out->print_cr("metaspace: NULL");
 516   }
 517 
 518 #ifdef CLD_DUMP_KLASSES
 519   if (Verbose) {
 520     ResourceMark rm;
 521     Klass* k = _klasses;
 522     while (k != NULL) {
 523       out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
 524           k->has_modified_oops(), k->has_accumulated_modified_oops());
 525       assert(k != k->next_link(), "no loops!");
 526       k = k->next_link();
 527     }
 528   }
 529 #endif  // CLD_DUMP_KLASSES
 530 #undef CLD_DUMP_KLASSES
 531   if (_jmethod_ids != NULL) {
 532     Method::print_jmethod_ids(this, out);
 533   }
 534   out->print_cr("}");
 535 }
 536 #endif // PRODUCT
 537 
 538 void ClassLoaderData::verify() {
 539   oop cl = class_loader();
 540 
 541   guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
 542   guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
 543 
 544   // Verify the integrity of the allocated space.
 545   if (metaspace_or_null() != NULL) {
 546     metaspace_or_null()->verify();
 547   }
 548 
 549   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 550     guarantee(k->class_loader_data() == this, "Must be the same");
 551     k->verify();
 552     assert(k != k->next_link(), "no loops!");
 553   }
 554 }
 555 
 556 bool ClassLoaderData::contains_klass(Klass* klass) {
 557   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
 558     if (k == klass) return true;
 559   }
 560   return false;
 561 }
 562 
 563 
 564 // GC root of class loader data created.
 565 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
 566 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
 567 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
 568 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
 569 
 570 bool ClassLoaderDataGraph::_should_purge = false;
 571 bool ClassLoaderDataGraph::_metaspace_oom = false;
 572 
 573 // Add a new class loader data node to the list.  Assign the newly created
 574 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
 575 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
 576   // We need to allocate all the oops for the ClassLoaderData before allocating the
 577   // actual ClassLoaderData object.
 578   ClassLoaderData::Dependencies dependencies(CHECK_NULL);
 579 
 580   NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
 581                                      // ClassLoaderData in the graph since the CLD
 582                                      // contains unhandled oops
 583 
 584   ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
 585 
 586 
 587   if (!is_anonymous) {
 588     ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
 589     // First, Atomically set it
 590     ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
 591     if (old != NULL) {
 592       delete cld;
 593       // Returns the data.
 594       return old;
 595     }
 596   }
 597 
 598   // We won the race, and therefore the task of adding the data to the list of
 599   // class loader data
 600   ClassLoaderData** list_head = &_head;
 601   ClassLoaderData* next = _head;
 602 
 603   do {
 604     cld->set_next(next);
 605     ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
 606     if (exchanged == next) {
 607       if (log_is_enabled(Debug, classloaderdata)) {
 608        PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
 609        log_creation(loader, cld, CHECK_NULL);
 610       }
 611       return cld;
 612     }
 613     next = exchanged;
 614   } while (true);
 615 }
 616 
 617 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) {
 618   Handle string;
 619   if (loader.not_null()) {
 620     // Include the result of loader.toString() in the output. This allows
 621     // the user of the log to identify the class loader instance.
 622     JavaValue result(T_OBJECT);
 623     KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass());
 624     JavaCalls::call_virtual(&result,
 625                             loader,
 626                             spec_klass,
 627                             vmSymbols::toString_name(),
 628                             vmSymbols::void_string_signature(),
 629                             CHECK);
 630     assert(result.get_type() == T_OBJECT, "just checking");
 631     string = (oop)result.get_jobject();
 632   }
 633 
 634   ResourceMark rm;
 635   outputStream* log = LogHandle(classloaderdata)::debug_stream();
 636   log->print("create class loader data " INTPTR_FORMAT, p2i(cld));
 637   log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
 638              cld->loader_name());
 639 
 640   if (string.not_null()) {
 641     log->print(": ");
 642     java_lang_String::print(string(), log);
 643   }
 644   log->cr();
 645 }
 646 
 647 
 648 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
 649   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
 650     cld->oops_do(f, klass_closure, must_claim);
 651   }
 652 }
 653 
 654 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
 655   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
 656     if (cld->keep_alive()) {
 657       cld->oops_do(f, klass_closure, must_claim);
 658     }
 659   }
 660 }
 661 
 662 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
 663   if (ClassUnloading) {
 664     keep_alive_oops_do(f, klass_closure, must_claim);
 665   } else {
 666     oops_do(f, klass_closure, must_claim);
 667   }
 668 }
 669 
 670 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
 671   for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
 672     cl->do_cld(cld);
 673   }
 674 }
 675 
 676 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
 677   for (ClassLoaderData* cld = _head;  cld != NULL; cld = cld->_next) {
 678     CLDClosure* closure = cld->keep_alive() ? strong : weak;
 679     if (closure != NULL) {
 680       closure->do_cld(cld);
 681     }
 682   }
 683 }
 684 
 685 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
 686   roots_cld_do(cl, NULL);
 687 }
 688 
 689 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
 690   if (ClassUnloading) {
 691     keep_alive_cld_do(cl);
 692   } else {
 693     cld_do(cl);
 694   }
 695 }
 696 
 697 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
 698   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
 699     cld->classes_do(klass_closure);
 700   }
 701 }
 702 
 703 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
 704   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
 705     cld->classes_do(f);
 706   }
 707 }
 708 
 709 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
 710   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
 711     cld->methods_do(f);
 712   }
 713 }
 714 
 715 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
 716   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
 717     cld->loaded_classes_do(klass_closure);
 718   }
 719 }
 720 
 721 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
 722   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
 723   // Only walk the head until any clds not purged from prior unloading
 724   // (CMS doesn't purge right away).
 725   for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
 726     cld->classes_do(f);
 727   }
 728 }
 729 
 730 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
 731   assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
 732 
 733   GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
 734 
 735   // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
 736   ClassLoaderData* curr = _head;
 737   while (curr != _saved_head) {
 738     if (!curr->claimed()) {
 739       array->push(curr);
 740 
 741       if (log_is_enabled(Debug, classloaderdata)) {
 742         outputStream* log = LogHandle(classloaderdata)::debug_stream();
 743         log->print("found new CLD: ");
 744         curr->print_value_on(log);
 745         log->cr();
 746       }
 747     }
 748 
 749     curr = curr->_next;
 750   }
 751 
 752   return array;
 753 }
 754 
 755 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
 756   assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
 757   for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
 758     if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
 759       return true;
 760     }
 761   }
 762   return false;
 763 }
 764 
 765 #ifndef PRODUCT
 766 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
 767   for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
 768     if (loader_data == data) {
 769       return true;
 770     }
 771   }
 772 
 773   return false;
 774 }
 775 #endif // PRODUCT
 776 
 777 
 778 // Move class loader data from main list to the unloaded list for unloading
 779 // and deallocation later.
 780 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
 781                                         bool clean_previous_versions) {
 782 
 783   ClassLoaderData* data = _head;
 784   ClassLoaderData* prev = NULL;
 785   bool seen_dead_loader = false;
 786 
 787   // Mark metadata seen on the stack only so we can delete unneeded entries.
 788   // Only walk all metadata, including the expensive code cache walk, for Full GC
 789   // and only if class redefinition and if there's previous versions of
 790   // Klasses to delete.
 791   bool walk_all_metadata = clean_previous_versions &&
 792                            JvmtiExport::has_redefined_a_class() &&
 793                            InstanceKlass::has_previous_versions();
 794   MetadataOnStackMark md_on_stack(walk_all_metadata);
 795 
 796   // Save previous _unloading pointer for CMS which may add to unloading list before
 797   // purging and we don't want to rewalk the previously unloaded class loader data.
 798   _saved_unloading = _unloading;
 799 
 800   data = _head;
 801   while (data != NULL) {
 802     if (data->is_alive(is_alive_closure)) {
 803       // clean metaspace
 804       if (walk_all_metadata) {
 805         data->classes_do(InstanceKlass::purge_previous_versions);
 806       }
 807       data->free_deallocate_list();
 808       prev = data;
 809       data = data->next();
 810       continue;
 811     }
 812     seen_dead_loader = true;
 813     ClassLoaderData* dead = data;
 814     dead->unload();
 815     data = data->next();
 816     // Remove from loader list.
 817     // This class loader data will no longer be found
 818     // in the ClassLoaderDataGraph.
 819     if (prev != NULL) {
 820       prev->set_next(data);
 821     } else {
 822       assert(dead == _head, "sanity check");
 823       _head = data;
 824     }
 825     dead->set_next(_unloading);
 826     _unloading = dead;
 827   }
 828 
 829   if (seen_dead_loader) {
 830     post_class_unload_events();
 831   }
 832 
 833   return seen_dead_loader;
 834 }
 835 
 836 void ClassLoaderDataGraph::purge() {
 837   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
 838   ClassLoaderData* list = _unloading;
 839   _unloading = NULL;
 840   ClassLoaderData* next = list;
 841   bool classes_unloaded = false;
 842   while (next != NULL) {
 843     ClassLoaderData* purge_me = next;
 844     next = purge_me->next();
 845     delete purge_me;
 846     classes_unloaded = true;
 847   }
 848   if (classes_unloaded) {
 849     Metaspace::purge();
 850     set_metaspace_oom(false);
 851   }
 852 }
 853 
 854 void ClassLoaderDataGraph::post_class_unload_events(void) {
 855 #if INCLUDE_TRACE
 856   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
 857   if (Tracing::enabled()) {
 858     if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
 859       assert(_unloading != NULL, "need class loader data unload list!");
 860       _class_unload_time = Ticks::now();
 861       classes_unloading_do(&class_unload_event);
 862     }
 863     Tracing::on_unloading_classes();
 864   }
 865 #endif
 866 }
 867 
 868 // CDS support
 869 
 870 // Global metaspaces for writing information to the shared archive.  When
 871 // application CDS is supported, we may need one per metaspace, so this
 872 // sort of looks like it.
 873 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
 874 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
 875 static bool _shared_metaspaces_initialized = false;
 876 
 877 // Initialize shared metaspaces (change to call from somewhere not lazily)
 878 void ClassLoaderData::initialize_shared_metaspaces() {
 879   assert(DumpSharedSpaces, "only use this for dumping shared spaces");
 880   assert(this == ClassLoaderData::the_null_class_loader_data(),
 881          "only supported for null loader data for now");
 882   assert (!_shared_metaspaces_initialized, "only initialize once");
 883   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);
 884   _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
 885   _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
 886   _shared_metaspaces_initialized = true;
 887 }
 888 
 889 Metaspace* ClassLoaderData::ro_metaspace() {
 890   assert(_ro_metaspace != NULL, "should already be initialized");
 891   return _ro_metaspace;
 892 }
 893 
 894 Metaspace* ClassLoaderData::rw_metaspace() {
 895   assert(_rw_metaspace != NULL, "should already be initialized");
 896   return _rw_metaspace;
 897 }
 898 
 899 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
 900     : _next_klass(NULL) {
 901   ClassLoaderData* cld = ClassLoaderDataGraph::_head;
 902   Klass* klass = NULL;
 903 
 904   // Find the first klass in the CLDG.
 905   while (cld != NULL) {
 906     klass = cld->_klasses;
 907     if (klass != NULL) {
 908       _next_klass = klass;
 909       return;
 910     }
 911     cld = cld->next();
 912   }
 913 }
 914 
 915 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
 916   Klass* next = klass->next_link();
 917   if (next != NULL) {
 918     return next;
 919   }
 920 
 921   // No more klasses in the current CLD. Time to find a new CLD.
 922   ClassLoaderData* cld = klass->class_loader_data();
 923   while (next == NULL) {
 924     cld = cld->next();
 925     if (cld == NULL) {
 926       break;
 927     }
 928     next = cld->_klasses;
 929   }
 930 
 931   return next;
 932 }
 933 
 934 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
 935   Klass* head = _next_klass;
 936 
 937   while (head != NULL) {
 938     Klass* next = next_klass_in_cldg(head);
 939 
 940     Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
 941 
 942     if (old_head == head) {
 943       return head; // Won the CAS.
 944     }
 945 
 946     head = old_head;
 947   }
 948 
 949   // Nothing more for the iterator to hand out.
 950   assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
 951   return NULL;
 952 }
 953 
 954 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
 955   _data = ClassLoaderDataGraph::_head;
 956 }
 957 
 958 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
 959 
 960 #ifndef PRODUCT
 961 // callable from debugger
 962 extern "C" int print_loader_data_graph() {
 963   ClassLoaderDataGraph::dump_on(tty);
 964   return 0;
 965 }
 966 
 967 void ClassLoaderDataGraph::verify() {
 968   for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
 969     data->verify();
 970   }
 971 }
 972 
 973 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
 974   for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
 975     data->dump(out);
 976   }
 977   MetaspaceAux::dump(out);
 978 }
 979 #endif // PRODUCT
 980 
 981 void ClassLoaderData::print_value_on(outputStream* out) const {
 982   if (class_loader() == NULL) {
 983     out->print("NULL class_loader");
 984   } else {
 985     out->print("class loader " INTPTR_FORMAT, p2i(this));
 986     class_loader()->print_value_on(out);
 987   }
 988 }
 989 
 990 #if INCLUDE_TRACE
 991 
 992 Ticks ClassLoaderDataGraph::_class_unload_time;
 993 
 994 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
 995 
 996   // post class unload event
 997   EventClassUnload event(UNTIMED);
 998   event.set_endtime(_class_unload_time);
 999   event.set_unloadedClass(k);
1000   oop defining_class_loader = k->class_loader();
1001   event.set_definingClassLoader(defining_class_loader != NULL ?
1002                                 defining_class_loader->klass() : (Klass*)NULL);
1003   event.commit();
1004 }
1005 
1006 #endif // INCLUDE_TRACE
--- EOF ---