1 /* 2 * Copyright (c) 2012, 2015, 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), 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(Klass* k, TRAPS) { 172 ClassLoaderData * const from_cld = this; 173 ClassLoaderData * const to_cld = k->class_loader_data(); 174 175 // Dependency to the null class loader data doesn't need to be recorded 176 // because the null class loader data never goes away. 177 if (to_cld->is_the_null_class_loader_data()) { 178 return; 179 } 180 181 oop to; 182 if (to_cld->is_anonymous()) { 183 // Anonymous class dependencies are through the mirror. 184 to = k->java_mirror(); 185 } else { 186 to = to_cld->class_loader(); 187 188 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 189 // we still have to add it. The class_loader won't keep from_cld alive. 190 if (!from_cld->is_anonymous()) { 191 // Check that this dependency isn't from the same or parent class_loader 192 oop from = from_cld->class_loader(); 193 194 oop curr = from; 195 while (curr != NULL) { 196 if (curr == to) { 197 return; // this class loader is in the parent list, no need to add it. 198 } 199 curr = java_lang_ClassLoader::parent(curr); 200 } 201 } 202 } 203 204 // It's a dependency we won't find through GC, add it. This is relatively rare 205 // Must handle over GC point. 206 Handle dependency(THREAD, to); 207 from_cld->_dependencies.add(dependency, CHECK); 208 } 209 210 211 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 212 // Check first if this dependency is already in the list. 213 // Save a pointer to the last to add to under the lock. 214 objArrayOop ok = _list_head; 215 objArrayOop last = NULL; 216 while (ok != NULL) { 217 last = ok; 218 if (ok->obj_at(0) == dependency()) { 219 // Don't need to add it 220 return; 221 } 222 ok = (objArrayOop)ok->obj_at(1); 223 } 224 225 // Must handle over GC points 226 assert (last != NULL, "dependencies should be initialized"); 227 objArrayHandle last_handle(THREAD, last); 228 229 // Create a new dependency node with fields for (class_loader or mirror, next) 230 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 231 deps->obj_at_put(0, dependency()); 232 233 // Must handle over GC points 234 objArrayHandle new_dependency(THREAD, deps); 235 236 // Add the dependency under lock 237 locked_add(last_handle, new_dependency, THREAD); 238 } 239 240 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 241 objArrayHandle new_dependency, 242 Thread* THREAD) { 243 244 // Have to lock and put the new dependency on the end of the dependency 245 // array so the card mark for CMS sees that this dependency is new. 246 // Can probably do this lock free with some effort. 247 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 248 249 oop loader_or_mirror = new_dependency->obj_at(0); 250 251 // Since the dependencies are only added, add to the end. 252 objArrayOop end = last_handle(); 253 objArrayOop last = NULL; 254 while (end != NULL) { 255 last = end; 256 // check again if another thread added it to the end. 257 if (end->obj_at(0) == loader_or_mirror) { 258 // Don't need to add it 259 return; 260 } 261 end = (objArrayOop)end->obj_at(1); 262 } 263 assert (last != NULL, "dependencies should be initialized"); 264 // fill in the first element with the oop in new_dependency. 265 if (last->obj_at(0) == NULL) { 266 last->obj_at_put(0, new_dependency->obj_at(0)); 267 } else { 268 last->obj_at_put(1, new_dependency()); 269 } 270 } 271 272 void ClassLoaderDataGraph::clear_claimed_marks() { 273 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 274 cld->clear_claimed(); 275 } 276 } 277 278 void ClassLoaderData::add_class(Klass* k) { 279 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 280 Klass* old_value = _klasses; 281 k->set_next_link(old_value); 282 // Make sure linked class is stable, since the class list is walked without a lock 283 OrderAccess::storestore(); 284 // link the new item into the list 285 _klasses = k; 286 287 if (log_is_enabled(Trace, classloaderdata) && k->class_loader_data() != NULL) { 288 ResourceMark rm; 289 outputStream* log = LogHandle(classloaderdata)::trace_stream(); 290 log->print_cr("Adding k: " PTR_FORMAT " %s to CLD: " 291 PTR_FORMAT " loader: " PTR_FORMAT " %s", 292 p2i(k), 293 k->external_name(), 294 p2i(k->class_loader_data()), 295 p2i((void *)k->class_loader()), 296 loader_name()); 297 } 298 } 299 300 // This is called by InstanceKlass::deallocate_contents() to remove the 301 // scratch_class for redefine classes. We need a lock because there it may not 302 // be called at a safepoint if there's an error. 303 void ClassLoaderData::remove_class(Klass* scratch_class) { 304 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 305 Klass* prev = NULL; 306 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 307 if (k == scratch_class) { 308 if (prev == NULL) { 309 _klasses = k->next_link(); 310 } else { 311 Klass* next = k->next_link(); 312 prev->set_next_link(next); 313 } 314 return; 315 } 316 prev = k; 317 assert(k != k->next_link(), "no loops!"); 318 } 319 ShouldNotReachHere(); // should have found this class!! 320 } 321 322 void ClassLoaderData::unload() { 323 _unloading = true; 324 325 // Tell serviceability tools these classes are unloading 326 classes_do(InstanceKlass::notify_unload_class); 327 328 if (log_is_enabled(Debug, classloaderdata)) { 329 ResourceMark rm; 330 outputStream* log = LogHandle(classloaderdata)::debug_stream(); 331 log->print(": unload loader data " INTPTR_FORMAT, p2i(this)); 332 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 333 loader_name()); 334 if (is_anonymous()) { 335 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 336 } 337 log->cr(); 338 } 339 } 340 341 oop ClassLoaderData::keep_alive_object() const { 342 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 343 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 344 } 345 346 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 347 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 348 || is_alive_closure->do_object_b(keep_alive_object()); 349 350 return alive; 351 } 352 353 354 ClassLoaderData::~ClassLoaderData() { 355 // Release C heap structures for all the classes. 356 classes_do(InstanceKlass::release_C_heap_structures); 357 358 Metaspace *m = _metaspace; 359 if (m != NULL) { 360 _metaspace = NULL; 361 // release the metaspace 362 delete m; 363 // release the handles 364 if (_handles != NULL) { 365 JNIHandleBlock::release_block(_handles); 366 _handles = NULL; 367 } 368 } 369 370 // Clear all the JNI handles for methods 371 // These aren't deallocated and are going to look like a leak, but that's 372 // needed because we can't really get rid of jmethodIDs because we don't 373 // know when native code is going to stop using them. The spec says that 374 // they're "invalid" but existing programs likely rely on their being 375 // NULL after class unloading. 376 if (_jmethod_ids != NULL) { 377 Method::clear_jmethod_ids(this); 378 } 379 // Delete lock 380 delete _metaspace_lock; 381 382 // Delete free list 383 if (_deallocate_list != NULL) { 384 delete _deallocate_list; 385 } 386 } 387 388 /** 389 * Returns true if this class loader data is for the extension class loader. 390 */ 391 bool ClassLoaderData::is_ext_class_loader_data() const { 392 return SystemDictionary::is_ext_class_loader(class_loader()); 393 } 394 395 Metaspace* ClassLoaderData::metaspace_non_null() { 396 assert(!DumpSharedSpaces, "wrong metaspace!"); 397 // If the metaspace has not been allocated, create a new one. Might want 398 // to create smaller arena for Reflection class loaders also. 399 // The reason for the delayed allocation is because some class loaders are 400 // simply for delegating with no metadata of their own. 401 if (_metaspace == NULL) { 402 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 403 // Check again if metaspace has been allocated while we were getting this lock. 404 if (_metaspace != NULL) { 405 return _metaspace; 406 } 407 if (this == the_null_class_loader_data()) { 408 assert (class_loader() == NULL, "Must be"); 409 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType)); 410 } else if (is_anonymous()) { 411 if (log_is_enabled(Trace, classloaderdata) && class_loader() != NULL) { 412 outputStream* log = LogHandle(classloaderdata)::trace_stream(); 413 log->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name()); 414 } 415 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType)); 416 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 417 if (log_is_enabled(Trace, classloaderdata) && class_loader() != NULL) { 418 outputStream* log = LogHandle(classloaderdata)::trace_stream(); 419 log->print_cr("is_reflection: %s", class_loader()->klass()->internal_name()); 420 } 421 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType)); 422 } else { 423 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType)); 424 } 425 } 426 return _metaspace; 427 } 428 429 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 430 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 431 432 jobject ClassLoaderData::add_handle(Handle h) { 433 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 434 if (handles() == NULL) { 435 set_handles(JNIHandleBlock::allocate_block()); 436 } 437 return handles()->allocate_handle(h()); 438 } 439 440 // Add this metadata pointer to be freed when it's safe. This is only during 441 // class unloading because Handles might point to this metadata field. 442 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 443 // Metadata in shared region isn't deleted. 444 if (!m->is_shared()) { 445 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 446 if (_deallocate_list == NULL) { 447 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 448 } 449 _deallocate_list->append_if_missing(m); 450 } 451 } 452 453 // Deallocate free metadata on the free list. How useful the PermGen was! 454 void ClassLoaderData::free_deallocate_list() { 455 // Don't need lock, at safepoint 456 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 457 if (_deallocate_list == NULL) { 458 return; 459 } 460 // Go backwards because this removes entries that are freed. 461 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 462 Metadata* m = _deallocate_list->at(i); 463 if (!m->on_stack()) { 464 _deallocate_list->remove_at(i); 465 // There are only three types of metadata that we deallocate directly. 466 // Cast them so they can be used by the template function. 467 if (m->is_method()) { 468 MetadataFactory::free_metadata(this, (Method*)m); 469 } else if (m->is_constantPool()) { 470 MetadataFactory::free_metadata(this, (ConstantPool*)m); 471 } else if (m->is_klass()) { 472 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 473 } else { 474 ShouldNotReachHere(); 475 } 476 } else { 477 // Metadata is alive. 478 // If scratch_class is on stack then it shouldn't be on this list! 479 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 480 "scratch classes on this list should be dead"); 481 // Also should assert that other metadata on the list was found in handles. 482 } 483 } 484 } 485 486 // These anonymous class loaders are to contain classes used for JSR292 487 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 488 // Add a new class loader data to the graph. 489 return ClassLoaderDataGraph::add(loader, true, THREAD); 490 } 491 492 const char* ClassLoaderData::loader_name() { 493 // Handles null class loader 494 return SystemDictionary::loader_name(class_loader()); 495 } 496 497 #ifndef PRODUCT 498 // Define to dump klasses 499 #undef CLD_DUMP_KLASSES 500 501 void ClassLoaderData::dump(outputStream * const out) { 502 ResourceMark rm; 503 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 504 p2i(this), p2i((void *)class_loader()), 505 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 506 if (claimed()) out->print(" claimed "); 507 if (is_unloading()) out->print(" unloading "); 508 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 509 out->cr(); 510 if (metaspace_or_null() != NULL) { 511 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 512 metaspace_or_null()->dump(out); 513 } else { 514 out->print_cr("metaspace: NULL"); 515 } 516 517 #ifdef CLD_DUMP_KLASSES 518 if (Verbose) { 519 ResourceMark rm; 520 Klass* k = _klasses; 521 while (k != NULL) { 522 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 523 k->has_modified_oops(), k->has_accumulated_modified_oops()); 524 assert(k != k->next_link(), "no loops!"); 525 k = k->next_link(); 526 } 527 } 528 #endif // CLD_DUMP_KLASSES 529 #undef CLD_DUMP_KLASSES 530 if (_jmethod_ids != NULL) { 531 Method::print_jmethod_ids(this, out); 532 } 533 out->print_cr("}"); 534 } 535 #endif // PRODUCT 536 537 void ClassLoaderData::verify() { 538 oop cl = class_loader(); 539 540 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 541 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 542 543 // Verify the integrity of the allocated space. 544 if (metaspace_or_null() != NULL) { 545 metaspace_or_null()->verify(); 546 } 547 548 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 549 guarantee(k->class_loader_data() == this, "Must be the same"); 550 k->verify(); 551 assert(k != k->next_link(), "no loops!"); 552 } 553 } 554 555 bool ClassLoaderData::contains_klass(Klass* klass) { 556 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 557 if (k == klass) return true; 558 } 559 return false; 560 } 561 562 563 // GC root of class loader data created. 564 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 565 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 566 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 567 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 568 569 bool ClassLoaderDataGraph::_should_purge = false; 570 bool ClassLoaderDataGraph::_metaspace_oom = false; 571 572 // Add a new class loader data node to the list. Assign the newly created 573 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 574 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 575 // We need to allocate all the oops for the ClassLoaderData before allocating the 576 // actual ClassLoaderData object. 577 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 578 ClassLoaderData* cld; 579 580 581 //BEGIN no_safepoints 582 { 583 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the 584 // ClassLoaderData in the graph since the CLD 585 // contains unhandled oops 586 587 cld = new ClassLoaderData(loader, is_anonymous, dependencies); 588 589 if (!is_anonymous) { 590 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 591 // First, Atomically set it 592 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 593 if (old != NULL) { 594 delete cld; 595 // Returns the data. 596 return old; 597 } 598 } 599 600 // We won the race, and therefore the task of adding the data to the list of 601 // class loader data 602 ClassLoaderData** list_head = &_head; 603 ClassLoaderData* next = _head; 604 605 do { 606 cld->set_next(next); 607 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 608 if (exchanged == next) { 609 break; 610 } 611 next = exchanged; 612 } while (true); 613 } 614 //END no_safepoints 615 616 // It's OK to do safe points now (and we need to do that in JavaCalls::call_virtual) 617 if (log_is_enabled(Debug, classloaderdata)) { 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_NULL); 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 return cld; 647 } 648 649 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 650 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 651 cld->oops_do(f, klass_closure, must_claim); 652 } 653 } 654 655 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 656 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 657 if (cld->keep_alive()) { 658 cld->oops_do(f, klass_closure, must_claim); 659 } 660 } 661 } 662 663 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 664 if (ClassUnloading) { 665 keep_alive_oops_do(f, klass_closure, must_claim); 666 } else { 667 oops_do(f, klass_closure, must_claim); 668 } 669 } 670 671 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 672 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 673 cl->do_cld(cld); 674 } 675 } 676 677 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 678 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 679 CLDClosure* closure = cld->keep_alive() ? strong : weak; 680 if (closure != NULL) { 681 closure->do_cld(cld); 682 } 683 } 684 } 685 686 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 687 roots_cld_do(cl, NULL); 688 } 689 690 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 691 if (ClassUnloading) { 692 keep_alive_cld_do(cl); 693 } else { 694 cld_do(cl); 695 } 696 } 697 698 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 699 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 700 cld->classes_do(klass_closure); 701 } 702 } 703 704 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 705 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 706 cld->classes_do(f); 707 } 708 } 709 710 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 711 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 712 cld->methods_do(f); 713 } 714 } 715 716 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 717 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 718 cld->loaded_classes_do(klass_closure); 719 } 720 } 721 722 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 723 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 724 // Only walk the head until any clds not purged from prior unloading 725 // (CMS doesn't purge right away). 726 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 727 cld->classes_do(f); 728 } 729 } 730 731 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 732 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 733 734 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 735 736 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 737 ClassLoaderData* curr = _head; 738 while (curr != _saved_head) { 739 if (!curr->claimed()) { 740 array->push(curr); 741 742 if (log_is_enabled(Debug, classloaderdata)) { 743 outputStream* log = LogHandle(classloaderdata)::debug_stream(); 744 log->print("[ClassLoaderData] found new CLD: "); 745 curr->print_value_on(log); 746 log->cr(); 747 } 748 } 749 750 curr = curr->_next; 751 } 752 753 return array; 754 } 755 756 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 757 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 758 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 759 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 760 return true; 761 } 762 } 763 return false; 764 } 765 766 #ifndef PRODUCT 767 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 768 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 769 if (loader_data == data) { 770 return true; 771 } 772 } 773 774 return false; 775 } 776 #endif // PRODUCT 777 778 779 // Move class loader data from main list to the unloaded list for unloading 780 // and deallocation later. 781 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 782 bool clean_previous_versions) { 783 784 ClassLoaderData* data = _head; 785 ClassLoaderData* prev = NULL; 786 bool seen_dead_loader = false; 787 788 // Mark metadata seen on the stack only so we can delete unneeded entries. 789 // Only walk all metadata, including the expensive code cache walk, for Full GC 790 // and only if class redefinition and if there's previous versions of 791 // Klasses to delete. 792 bool walk_all_metadata = clean_previous_versions && 793 JvmtiExport::has_redefined_a_class() && 794 InstanceKlass::has_previous_versions(); 795 MetadataOnStackMark md_on_stack(walk_all_metadata); 796 797 // Save previous _unloading pointer for CMS which may add to unloading list before 798 // purging and we don't want to rewalk the previously unloaded class loader data. 799 _saved_unloading = _unloading; 800 801 data = _head; 802 while (data != NULL) { 803 if (data->is_alive(is_alive_closure)) { 804 // clean metaspace 805 if (walk_all_metadata) { 806 data->classes_do(InstanceKlass::purge_previous_versions); 807 } 808 data->free_deallocate_list(); 809 prev = data; 810 data = data->next(); 811 continue; 812 } 813 seen_dead_loader = true; 814 ClassLoaderData* dead = data; 815 dead->unload(); 816 data = data->next(); 817 // Remove from loader list. 818 // This class loader data will no longer be found 819 // in the ClassLoaderDataGraph. 820 if (prev != NULL) { 821 prev->set_next(data); 822 } else { 823 assert(dead == _head, "sanity check"); 824 _head = data; 825 } 826 dead->set_next(_unloading); 827 _unloading = dead; 828 } 829 830 if (seen_dead_loader) { 831 post_class_unload_events(); 832 } 833 834 return seen_dead_loader; 835 } 836 837 void ClassLoaderDataGraph::purge() { 838 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 839 ClassLoaderData* list = _unloading; 840 _unloading = NULL; 841 ClassLoaderData* next = list; 842 bool classes_unloaded = false; 843 while (next != NULL) { 844 ClassLoaderData* purge_me = next; 845 next = purge_me->next(); 846 delete purge_me; 847 classes_unloaded = true; 848 } 849 if (classes_unloaded) { 850 Metaspace::purge(); 851 set_metaspace_oom(false); 852 } 853 } 854 855 void ClassLoaderDataGraph::post_class_unload_events(void) { 856 #if INCLUDE_TRACE 857 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 858 if (Tracing::enabled()) { 859 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 860 assert(_unloading != NULL, "need class loader data unload list!"); 861 _class_unload_time = Ticks::now(); 862 classes_unloading_do(&class_unload_event); 863 } 864 Tracing::on_unloading_classes(); 865 } 866 #endif 867 } 868 869 // CDS support 870 871 // Global metaspaces for writing information to the shared archive. When 872 // application CDS is supported, we may need one per metaspace, so this 873 // sort of looks like it. 874 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 875 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 876 static bool _shared_metaspaces_initialized = false; 877 878 // Initialize shared metaspaces (change to call from somewhere not lazily) 879 void ClassLoaderData::initialize_shared_metaspaces() { 880 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 881 assert(this == ClassLoaderData::the_null_class_loader_data(), 882 "only supported for null loader data for now"); 883 assert (!_shared_metaspaces_initialized, "only initialize once"); 884 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 885 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 886 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 887 _shared_metaspaces_initialized = true; 888 } 889 890 Metaspace* ClassLoaderData::ro_metaspace() { 891 assert(_ro_metaspace != NULL, "should already be initialized"); 892 return _ro_metaspace; 893 } 894 895 Metaspace* ClassLoaderData::rw_metaspace() { 896 assert(_rw_metaspace != NULL, "should already be initialized"); 897 return _rw_metaspace; 898 } 899 900 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 901 : _next_klass(NULL) { 902 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 903 Klass* klass = NULL; 904 905 // Find the first klass in the CLDG. 906 while (cld != NULL) { 907 klass = cld->_klasses; 908 if (klass != NULL) { 909 _next_klass = klass; 910 return; 911 } 912 cld = cld->next(); 913 } 914 } 915 916 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 917 Klass* next = klass->next_link(); 918 if (next != NULL) { 919 return next; 920 } 921 922 // No more klasses in the current CLD. Time to find a new CLD. 923 ClassLoaderData* cld = klass->class_loader_data(); 924 while (next == NULL) { 925 cld = cld->next(); 926 if (cld == NULL) { 927 break; 928 } 929 next = cld->_klasses; 930 } 931 932 return next; 933 } 934 935 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 936 Klass* head = _next_klass; 937 938 while (head != NULL) { 939 Klass* next = next_klass_in_cldg(head); 940 941 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 942 943 if (old_head == head) { 944 return head; // Won the CAS. 945 } 946 947 head = old_head; 948 } 949 950 // Nothing more for the iterator to hand out. 951 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 952 return NULL; 953 } 954 955 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 956 _data = ClassLoaderDataGraph::_head; 957 } 958 959 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 960 961 #ifndef PRODUCT 962 // callable from debugger 963 extern "C" int print_loader_data_graph() { 964 ClassLoaderDataGraph::dump_on(tty); 965 return 0; 966 } 967 968 void ClassLoaderDataGraph::verify() { 969 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 970 data->verify(); 971 } 972 } 973 974 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 975 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 976 data->dump(out); 977 } 978 MetaspaceAux::dump(out); 979 } 980 #endif // PRODUCT 981 982 void ClassLoaderData::print_value_on(outputStream* out) const { 983 if (class_loader() == NULL) { 984 out->print("NULL class_loader"); 985 } else { 986 out->print("class loader " INTPTR_FORMAT, p2i(this)); 987 class_loader()->print_value_on(out); 988 } 989 } 990 991 #if INCLUDE_TRACE 992 993 Ticks ClassLoaderDataGraph::_class_unload_time; 994 995 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 996 997 // post class unload event 998 EventClassUnload event(UNTIMED); 999 event.set_endtime(_class_unload_time); 1000 event.set_unloadedClass(k); 1001 oop defining_class_loader = k->class_loader(); 1002 event.set_definingClassLoader(defining_class_loader != NULL ? 1003 defining_class_loader->klass() : (Klass*)NULL); 1004 event.commit(); 1005 } 1006 1007 #endif // INCLUDE_TRACE