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