1 /* 2 * Copyright (c) 2012, 2014, 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 "memory/gcLocker.hpp" 57 #include "memory/metadataFactory.hpp" 58 #include "memory/metaspaceShared.hpp" 59 #include "memory/oopFactory.hpp" 60 #include "runtime/atomic.inline.hpp" 61 #include "runtime/jniHandles.hpp" 62 #include "runtime/mutex.hpp" 63 #include "runtime/safepoint.hpp" 64 #include "runtime/synchronizer.hpp" 65 #include "utilities/growableArray.hpp" 66 #include "utilities/macros.hpp" 67 #include "utilities/ostream.hpp" 68 69 #if INCLUDE_TRACE 70 #include "trace/tracing.hpp" 71 #endif 72 73 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 74 75 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 76 _class_loader(h_class_loader()), 77 _is_anonymous(is_anonymous), 78 // An anonymous class loader data doesn't have anything to keep 79 // it from being unloaded during parsing of the anonymous class. 80 // The null-class-loader should always be kept alive. 81 _keep_alive(is_anonymous || h_class_loader.is_null()), 82 _metaspace(NULL), _unloading(false), _klasses(NULL), 83 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL), 84 _next(NULL), _dependencies(dependencies), 85 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) { 86 // empty 87 } 88 89 void ClassLoaderData::init_dependencies(TRAPS) { 90 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 91 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 92 _dependencies.init(CHECK); 93 } 94 95 void ClassLoaderData::Dependencies::init(TRAPS) { 96 // Create empty dependencies array to add to. CMS requires this to be 97 // an oop so that it can track additions via card marks. We think. 98 _list_head = oopFactory::new_objectArray(2, CHECK); 99 } 100 101 bool ClassLoaderData::claim() { 102 if (_claimed == 1) { 103 return false; 104 } 105 106 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 107 } 108 109 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 110 if (must_claim && !claim()) { 111 return; 112 } 113 114 f->do_oop(&_class_loader); 115 _dependencies.oops_do(f); 116 _handles->oops_do(f); 117 if (klass_closure != NULL) { 118 classes_do(klass_closure); 119 } 120 } 121 122 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 123 f->do_oop((oop*)&_list_head); 124 } 125 126 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 127 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 128 klass_closure->do_klass(k); 129 assert(k != k->next_link(), "no loops!"); 130 } 131 } 132 133 void ClassLoaderData::classes_do(void f(Klass * const)) { 134 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 135 f(k); 136 } 137 } 138 139 void ClassLoaderData::methods_do(void f(Method*)) { 140 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 141 if (k->oop_is_instance()) { 142 InstanceKlass::cast(k)->methods_do(f); 143 } 144 } 145 } 146 147 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 148 // Lock to avoid classes being modified/added/removed during iteration 149 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 150 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 151 // Do not filter ArrayKlass oops here... 152 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) { 153 klass_closure->do_klass(k); 154 } 155 } 156 } 157 158 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 159 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 160 if (k->oop_is_instance()) { 161 f(InstanceKlass::cast(k)); 162 } 163 assert(k != k->next_link(), "no loops!"); 164 } 165 } 166 167 void ClassLoaderData::record_dependency(Klass* k, TRAPS) { 168 ClassLoaderData * const from_cld = this; 169 ClassLoaderData * const to_cld = k->class_loader_data(); 170 171 // Dependency to the null class loader data doesn't need to be recorded 172 // because the null class loader data never goes away. 173 if (to_cld->is_the_null_class_loader_data()) { 174 return; 175 } 176 177 oop to; 178 if (to_cld->is_anonymous()) { 179 // Anonymous class dependencies are through the mirror. 180 to = k->java_mirror(); 181 } else { 182 to = to_cld->class_loader(); 183 184 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 185 // we still have to add it. The class_loader won't keep from_cld alive. 186 if (!from_cld->is_anonymous()) { 187 // Check that this dependency isn't from the same or parent class_loader 188 oop from = from_cld->class_loader(); 189 190 oop curr = from; 191 while (curr != NULL) { 192 if (curr == to) { 193 return; // this class loader is in the parent list, no need to add it. 194 } 195 curr = java_lang_ClassLoader::parent(curr); 196 } 197 } 198 } 199 200 // It's a dependency we won't find through GC, add it. This is relatively rare 201 // Must handle over GC point. 202 Handle dependency(THREAD, to); 203 from_cld->_dependencies.add(dependency, CHECK); 204 } 205 206 207 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 208 // Check first if this dependency is already in the list. 209 // Save a pointer to the last to add to under the lock. 210 objArrayOop ok = _list_head; 211 objArrayOop last = NULL; 212 while (ok != NULL) { 213 last = ok; 214 if (ok->obj_at(0) == dependency()) { 215 // Don't need to add it 216 return; 217 } 218 ok = (objArrayOop)ok->obj_at(1); 219 } 220 221 // Must handle over GC points 222 assert (last != NULL, "dependencies should be initialized"); 223 objArrayHandle last_handle(THREAD, last); 224 225 // Create a new dependency node with fields for (class_loader or mirror, next) 226 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 227 deps->obj_at_put(0, dependency()); 228 229 // Must handle over GC points 230 objArrayHandle new_dependency(THREAD, deps); 231 232 // Add the dependency under lock 233 locked_add(last_handle, new_dependency, THREAD); 234 } 235 236 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 237 objArrayHandle new_dependency, 238 Thread* THREAD) { 239 240 // Have to lock and put the new dependency on the end of the dependency 241 // array so the card mark for CMS sees that this dependency is new. 242 // Can probably do this lock free with some effort. 243 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 244 245 oop loader_or_mirror = new_dependency->obj_at(0); 246 247 // Since the dependencies are only added, add to the end. 248 objArrayOop end = last_handle(); 249 objArrayOop last = NULL; 250 while (end != NULL) { 251 last = end; 252 // check again if another thread added it to the end. 253 if (end->obj_at(0) == loader_or_mirror) { 254 // Don't need to add it 255 return; 256 } 257 end = (objArrayOop)end->obj_at(1); 258 } 259 assert (last != NULL, "dependencies should be initialized"); 260 // fill in the first element with the oop in new_dependency. 261 if (last->obj_at(0) == NULL) { 262 last->obj_at_put(0, new_dependency->obj_at(0)); 263 } else { 264 last->obj_at_put(1, new_dependency()); 265 } 266 } 267 268 void ClassLoaderDataGraph::clear_claimed_marks() { 269 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 270 cld->clear_claimed(); 271 } 272 } 273 274 void ClassLoaderData::add_class(Klass* k) { 275 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 276 Klass* old_value = _klasses; 277 k->set_next_link(old_value); 278 // Make sure linked class is stable, since the class list is walked without a lock 279 OrderAccess::storestore(); 280 // link the new item into the list 281 _klasses = k; 282 283 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) { 284 ResourceMark rm; 285 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: " 286 PTR_FORMAT " loader: " PTR_FORMAT " %s", 287 p2i(k), 288 k->external_name(), 289 p2i(k->class_loader_data()), 290 p2i((void *)k->class_loader()), 291 loader_name()); 292 } 293 } 294 295 // This is called by InstanceKlass::deallocate_contents() to remove the 296 // scratch_class for redefine classes. We need a lock because there it may not 297 // be called at a safepoint if there's an error. 298 void ClassLoaderData::remove_class(Klass* scratch_class) { 299 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 300 Klass* prev = NULL; 301 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 302 if (k == scratch_class) { 303 if (prev == NULL) { 304 _klasses = k->next_link(); 305 } else { 306 Klass* next = k->next_link(); 307 prev->set_next_link(next); 308 } 309 return; 310 } 311 prev = k; 312 assert(k != k->next_link(), "no loops!"); 313 } 314 ShouldNotReachHere(); // should have found this class!! 315 } 316 317 void ClassLoaderData::unload() { 318 _unloading = true; 319 320 // Tell serviceability tools these classes are unloading 321 classes_do(InstanceKlass::notify_unload_class); 322 323 if (TraceClassLoaderData) { 324 ResourceMark rm; 325 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this)); 326 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 327 loader_name()); 328 if (is_anonymous()) { 329 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 330 } 331 tty->print_cr("]"); 332 } 333 } 334 335 #ifdef ASSERT 336 class AllAliveClosure : public OopClosure { 337 BoolObjectClosure* _is_alive_closure; 338 bool _found_dead; 339 public: 340 AllAliveClosure(BoolObjectClosure* is_alive_closure) : _is_alive_closure(is_alive_closure), _found_dead(false) {} 341 template <typename T> void do_oop_work(T* p) { 342 T heap_oop = oopDesc::load_heap_oop(p); 343 if (!oopDesc::is_null(heap_oop)) { 344 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 345 if (!_is_alive_closure->do_object_b(obj)) { 346 _found_dead = true; 347 } 348 } 349 } 350 void do_oop(oop* p) { do_oop_work<oop>(p); } 351 void do_oop(narrowOop* p) { do_oop_work<narrowOop>(p); } 352 bool found_dead() { return _found_dead; } 353 }; 354 #endif 355 356 oop ClassLoaderData::keep_alive_object() const { 357 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 358 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 359 } 360 361 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 362 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 363 || is_alive_closure->do_object_b(keep_alive_object()); 364 365 #ifdef ASSERT 366 if (alive) { 367 AllAliveClosure all_alive_closure(is_alive_closure); 368 KlassToOopClosure klass_closure(&all_alive_closure); 369 const_cast<ClassLoaderData*>(this)->oops_do(&all_alive_closure, &klass_closure, false); 370 assert(!all_alive_closure.found_dead(), err_msg("Found dead oop in alive cld: " PTR_FORMAT, p2i(this))); 371 } 372 #endif 373 374 return alive; 375 } 376 377 378 ClassLoaderData::~ClassLoaderData() { 379 // Release C heap structures for all the classes. 380 classes_do(InstanceKlass::release_C_heap_structures); 381 382 Metaspace *m = _metaspace; 383 if (m != NULL) { 384 _metaspace = NULL; 385 // release the metaspace 386 delete m; 387 // release the handles 388 if (_handles != NULL) { 389 JNIHandleBlock::release_block(_handles); 390 _handles = NULL; 391 } 392 } 393 394 // Clear all the JNI handles for methods 395 // These aren't deallocated and are going to look like a leak, but that's 396 // needed because we can't really get rid of jmethodIDs because we don't 397 // know when native code is going to stop using them. The spec says that 398 // they're "invalid" but existing programs likely rely on their being 399 // NULL after class unloading. 400 if (_jmethod_ids != NULL) { 401 Method::clear_jmethod_ids(this); 402 } 403 // Delete lock 404 delete _metaspace_lock; 405 406 // Delete free list 407 if (_deallocate_list != NULL) { 408 delete _deallocate_list; 409 } 410 } 411 412 /** 413 * Returns true if this class loader data is for the extension class loader. 414 */ 415 bool ClassLoaderData::is_ext_class_loader_data() const { 416 return SystemDictionary::is_ext_class_loader(class_loader()); 417 } 418 419 Metaspace* ClassLoaderData::metaspace_non_null() { 420 assert(!DumpSharedSpaces, "wrong metaspace!"); 421 // If the metaspace has not been allocated, create a new one. Might want 422 // to create smaller arena for Reflection class loaders also. 423 // The reason for the delayed allocation is because some class loaders are 424 // simply for delegating with no metadata of their own. 425 if (_metaspace == NULL) { 426 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 427 // Check again if metaspace has been allocated while we were getting this lock. 428 if (_metaspace != NULL) { 429 return _metaspace; 430 } 431 if (this == the_null_class_loader_data()) { 432 assert (class_loader() == NULL, "Must be"); 433 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType)); 434 } else if (is_anonymous()) { 435 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 436 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name()); 437 } 438 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType)); 439 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 440 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 441 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name()); 442 } 443 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType)); 444 } else { 445 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType)); 446 } 447 } 448 return _metaspace; 449 } 450 451 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 452 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 453 454 jobject ClassLoaderData::add_handle(Handle h) { 455 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 456 if (handles() == NULL) { 457 set_handles(JNIHandleBlock::allocate_block()); 458 } 459 return handles()->allocate_handle(h()); 460 } 461 462 // Add this metadata pointer to be freed when it's safe. This is only during 463 // class unloading because Handles might point to this metadata field. 464 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 465 // Metadata in shared region isn't deleted. 466 if (!m->is_shared()) { 467 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 468 if (_deallocate_list == NULL) { 469 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 470 } 471 _deallocate_list->append_if_missing(m); 472 } 473 } 474 475 // Deallocate free metadata on the free list. How useful the PermGen was! 476 void ClassLoaderData::free_deallocate_list() { 477 // Don't need lock, at safepoint 478 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 479 if (_deallocate_list == NULL) { 480 return; 481 } 482 // Go backwards because this removes entries that are freed. 483 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 484 Metadata* m = _deallocate_list->at(i); 485 if (!m->on_stack()) { 486 _deallocate_list->remove_at(i); 487 // There are only three types of metadata that we deallocate directly. 488 // Cast them so they can be used by the template function. 489 if (m->is_method()) { 490 MetadataFactory::free_metadata(this, (Method*)m); 491 } else if (m->is_constantPool()) { 492 MetadataFactory::free_metadata(this, (ConstantPool*)m); 493 } else if (m->is_klass()) { 494 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 495 } else { 496 ShouldNotReachHere(); 497 } 498 } 499 } 500 } 501 502 // These anonymous class loaders are to contain classes used for JSR292 503 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 504 // Add a new class loader data to the graph. 505 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL); 506 } 507 508 const char* ClassLoaderData::loader_name() { 509 // Handles null class loader 510 return SystemDictionary::loader_name(class_loader()); 511 } 512 513 #ifndef PRODUCT 514 // Define to dump klasses 515 #undef CLD_DUMP_KLASSES 516 517 void ClassLoaderData::dump(outputStream * const out) { 518 ResourceMark rm; 519 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {", 520 p2i(this), p2i((void *)class_loader()), 521 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 522 if (claimed()) out->print(" claimed "); 523 if (is_unloading()) out->print(" unloading "); 524 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 525 out->cr(); 526 if (metaspace_or_null() != NULL) { 527 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 528 metaspace_or_null()->dump(out); 529 } else { 530 out->print_cr("metaspace: NULL"); 531 } 532 533 #ifdef CLD_DUMP_KLASSES 534 if (Verbose) { 535 ResourceMark rm; 536 Klass* k = _klasses; 537 while (k != NULL) { 538 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 539 k->has_modified_oops(), k->has_accumulated_modified_oops()); 540 assert(k != k->next_link(), "no loops!"); 541 k = k->next_link(); 542 } 543 } 544 #endif // CLD_DUMP_KLASSES 545 #undef CLD_DUMP_KLASSES 546 if (_jmethod_ids != NULL) { 547 Method::print_jmethod_ids(this, out); 548 } 549 out->print_cr("}"); 550 } 551 #endif // PRODUCT 552 553 void ClassLoaderData::verify() { 554 oop cl = class_loader(); 555 556 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 557 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 558 559 // Verify the integrity of the allocated space. 560 if (metaspace_or_null() != NULL) { 561 metaspace_or_null()->verify(); 562 } 563 564 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 565 guarantee(k->class_loader_data() == this, "Must be the same"); 566 k->verify(); 567 assert(k != k->next_link(), "no loops!"); 568 } 569 } 570 571 bool ClassLoaderData::contains_klass(Klass* klass) { 572 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 573 if (k == klass) return true; 574 } 575 return false; 576 } 577 578 579 // GC root of class loader data created. 580 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 581 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 582 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 583 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 584 585 bool ClassLoaderDataGraph::_should_purge = false; 586 587 // Add a new class loader data node to the list. Assign the newly created 588 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 589 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 590 // We need to allocate all the oops for the ClassLoaderData before allocating the 591 // actual ClassLoaderData object. 592 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 593 594 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the 595 // ClassLoaderData in the graph since the CLD 596 // contains unhandled oops 597 598 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 599 600 601 if (!is_anonymous) { 602 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 603 // First, Atomically set it 604 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 605 if (old != NULL) { 606 delete cld; 607 // Returns the data. 608 return old; 609 } 610 } 611 612 // We won the race, and therefore the task of adding the data to the list of 613 // class loader data 614 ClassLoaderData** list_head = &_head; 615 ClassLoaderData* next = _head; 616 617 do { 618 cld->set_next(next); 619 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 620 if (exchanged == next) { 621 if (TraceClassLoaderData) { 622 ResourceMark rm; 623 tty->print("[ClassLoaderData: "); 624 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 625 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 626 cld->loader_name()); 627 tty->print_cr("]"); 628 } 629 return cld; 630 } 631 next = exchanged; 632 } while (true); 633 634 } 635 636 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 637 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 638 cld->oops_do(f, klass_closure, must_claim); 639 } 640 } 641 642 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 643 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 644 if (cld->keep_alive()) { 645 cld->oops_do(f, klass_closure, must_claim); 646 } 647 } 648 } 649 650 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 651 if (ClassUnloading) { 652 keep_alive_oops_do(f, klass_closure, must_claim); 653 } else { 654 oops_do(f, klass_closure, must_claim); 655 } 656 } 657 658 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 659 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 660 cl->do_cld(cld); 661 } 662 } 663 664 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 665 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 666 CLDClosure* closure = cld->keep_alive() ? strong : weak; 667 if (closure != NULL) { 668 closure->do_cld(cld); 669 } 670 } 671 } 672 673 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 674 roots_cld_do(cl, NULL); 675 } 676 677 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 678 if (ClassUnloading) { 679 keep_alive_cld_do(cl); 680 } else { 681 cld_do(cl); 682 } 683 } 684 685 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 686 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 687 cld->classes_do(klass_closure); 688 } 689 } 690 691 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 692 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 693 cld->classes_do(f); 694 } 695 } 696 697 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 698 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 699 cld->methods_do(f); 700 } 701 } 702 703 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 704 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 705 cld->loaded_classes_do(klass_closure); 706 } 707 } 708 709 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 710 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 711 // Only walk the head until any clds not purged from prior unloading 712 // (CMS doesn't purge right away). 713 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 714 cld->classes_do(f); 715 } 716 } 717 718 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 719 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 720 721 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 722 723 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 724 ClassLoaderData* curr = _head; 725 while (curr != _saved_head) { 726 if (!curr->claimed()) { 727 array->push(curr); 728 729 if (TraceClassLoaderData) { 730 tty->print("[ClassLoaderData] found new CLD: "); 731 curr->print_value_on(tty); 732 tty->cr(); 733 } 734 } 735 736 curr = curr->_next; 737 } 738 739 return array; 740 } 741 742 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 743 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 744 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 745 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 746 return true; 747 } 748 } 749 return false; 750 } 751 752 #ifndef PRODUCT 753 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 754 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 755 if (loader_data == data) { 756 return true; 757 } 758 } 759 760 return false; 761 } 762 #endif // PRODUCT 763 764 765 // Move class loader data from main list to the unloaded list for unloading 766 // and deallocation later. 767 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) { 768 ClassLoaderData* data = _head; 769 ClassLoaderData* prev = NULL; 770 bool seen_dead_loader = false; 771 772 // Save previous _unloading pointer for CMS which may add to unloading list before 773 // purging and we don't want to rewalk the previously unloaded class loader data. 774 _saved_unloading = _unloading; 775 776 // mark metadata seen on the stack and code cache so we can delete 777 // unneeded entries. 778 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class(); 779 MetadataOnStackMark md_on_stack(has_redefined_a_class); 780 if (has_redefined_a_class) { 781 // purge_previous_versions also cleans weak method links. Because 782 // one method's MDO can reference another method from another 783 // class loader, we need to first clean weak method links for all 784 // class loaders here. Below, we can then free redefined methods 785 // for all class loaders. 786 while (data != NULL) { 787 if (data->is_alive(is_alive_closure)) { 788 data->classes_do(InstanceKlass::purge_previous_versions); 789 } 790 data = data->next(); 791 } 792 } 793 data = _head; 794 while (data != NULL) { 795 if (data->is_alive(is_alive_closure)) { 796 data->free_deallocate_list(); 797 prev = data; 798 data = data->next(); 799 continue; 800 } 801 seen_dead_loader = true; 802 ClassLoaderData* dead = data; 803 dead->unload(); 804 data = data->next(); 805 // Remove from loader list. 806 // This class loader data will no longer be found 807 // in the ClassLoaderDataGraph. 808 if (prev != NULL) { 809 prev->set_next(data); 810 } else { 811 assert(dead == _head, "sanity check"); 812 _head = data; 813 } 814 dead->set_next(_unloading); 815 _unloading = dead; 816 } 817 818 if (seen_dead_loader) { 819 post_class_unload_events(); 820 } 821 822 return seen_dead_loader; 823 } 824 825 void ClassLoaderDataGraph::purge() { 826 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 827 ClassLoaderData* list = _unloading; 828 _unloading = NULL; 829 ClassLoaderData* next = list; 830 while (next != NULL) { 831 ClassLoaderData* purge_me = next; 832 next = purge_me->next(); 833 delete purge_me; 834 } 835 Metaspace::purge(); 836 } 837 838 void ClassLoaderDataGraph::post_class_unload_events(void) { 839 #if INCLUDE_TRACE 840 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 841 if (Tracing::enabled()) { 842 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 843 assert(_unloading != NULL, "need class loader data unload list!"); 844 _class_unload_time = Ticks::now(); 845 classes_unloading_do(&class_unload_event); 846 } 847 Tracing::on_unloading_classes(); 848 } 849 #endif 850 } 851 852 // CDS support 853 854 // Global metaspaces for writing information to the shared archive. When 855 // application CDS is supported, we may need one per metaspace, so this 856 // sort of looks like it. 857 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 858 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 859 static bool _shared_metaspaces_initialized = false; 860 861 // Initialize shared metaspaces (change to call from somewhere not lazily) 862 void ClassLoaderData::initialize_shared_metaspaces() { 863 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 864 assert(this == ClassLoaderData::the_null_class_loader_data(), 865 "only supported for null loader data for now"); 866 assert (!_shared_metaspaces_initialized, "only initialize once"); 867 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 868 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 869 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 870 _shared_metaspaces_initialized = true; 871 } 872 873 Metaspace* ClassLoaderData::ro_metaspace() { 874 assert(_ro_metaspace != NULL, "should already be initialized"); 875 return _ro_metaspace; 876 } 877 878 Metaspace* ClassLoaderData::rw_metaspace() { 879 assert(_rw_metaspace != NULL, "should already be initialized"); 880 return _rw_metaspace; 881 } 882 883 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 884 : _next_klass(NULL) { 885 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 886 Klass* klass = NULL; 887 888 // Find the first klass in the CLDG. 889 while (cld != NULL) { 890 klass = cld->_klasses; 891 if (klass != NULL) { 892 _next_klass = klass; 893 return; 894 } 895 cld = cld->next(); 896 } 897 } 898 899 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 900 Klass* next = klass->next_link(); 901 if (next != NULL) { 902 return next; 903 } 904 905 // No more klasses in the current CLD. Time to find a new CLD. 906 ClassLoaderData* cld = klass->class_loader_data(); 907 while (next == NULL) { 908 cld = cld->next(); 909 if (cld == NULL) { 910 break; 911 } 912 next = cld->_klasses; 913 } 914 915 return next; 916 } 917 918 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 919 Klass* head = (Klass*)_next_klass; 920 921 while (head != NULL) { 922 Klass* next = next_klass_in_cldg(head); 923 924 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 925 926 if (old_head == head) { 927 return head; // Won the CAS. 928 } 929 930 head = old_head; 931 } 932 933 // Nothing more for the iterator to hand out. 934 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head))); 935 return NULL; 936 } 937 938 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 939 _data = ClassLoaderDataGraph::_head; 940 } 941 942 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 943 944 #ifndef PRODUCT 945 // callable from debugger 946 extern "C" int print_loader_data_graph() { 947 ClassLoaderDataGraph::dump_on(tty); 948 return 0; 949 } 950 951 void ClassLoaderDataGraph::verify() { 952 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 953 data->verify(); 954 } 955 } 956 957 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 958 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 959 data->dump(out); 960 } 961 MetaspaceAux::dump(out); 962 } 963 #endif // PRODUCT 964 965 void ClassLoaderData::print_value_on(outputStream* out) const { 966 if (class_loader() == NULL) { 967 out->print("NULL class_loader"); 968 } else { 969 out->print("class loader " INTPTR_FORMAT, p2i(this)); 970 class_loader()->print_value_on(out); 971 } 972 } 973 974 #if INCLUDE_TRACE 975 976 Ticks ClassLoaderDataGraph::_class_unload_time; 977 978 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 979 980 // post class unload event 981 EventClassUnload event(UNTIMED); 982 event.set_endtime(_class_unload_time); 983 event.set_unloadedClass(k); 984 oop defining_class_loader = k->class_loader(); 985 event.set_definingClassLoader(defining_class_loader != NULL ? 986 defining_class_loader->klass() : (Klass*)NULL); 987 event.commit(); 988 } 989 990 #endif /* INCLUDE_TRACE */