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 #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 // Make sure linked class is stable, since the class list is walked without a lock 278 OrderAccess::storestore(); 279 // link the new item into the list 280 _klasses = k; 281 282 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) { 283 ResourceMark rm; 284 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: " 285 PTR_FORMAT " loader: " PTR_FORMAT " %s", 286 p2i(k), 287 k->external_name(), 288 p2i(k->class_loader_data()), 289 p2i((void *)k->class_loader()), 290 loader_name()); 291 } 292 } 293 294 // This is called by InstanceKlass::deallocate_contents() to remove the 295 // scratch_class for redefine classes. We need a lock because there it may not 296 // be called at a safepoint if there's an error. 297 void ClassLoaderData::remove_class(Klass* scratch_class) { 298 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 299 Klass* prev = NULL; 300 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 301 if (k == scratch_class) { 302 if (prev == NULL) { 303 _klasses = k->next_link(); 304 } else { 305 Klass* next = k->next_link(); 306 prev->set_next_link(next); 307 } 308 return; 309 } 310 prev = k; 311 assert(k != k->next_link(), "no loops!"); 312 } 313 ShouldNotReachHere(); // should have found this class!! 314 } 315 316 void ClassLoaderData::unload() { 317 _unloading = true; 318 319 // Tell serviceability tools these classes are unloading 320 classes_do(InstanceKlass::notify_unload_class); 321 322 if (TraceClassLoaderData) { 323 ResourceMark rm; 324 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this)); 325 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 326 loader_name()); 327 if (is_anonymous()) { 328 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 329 } 330 tty->print_cr("]"); 331 } 332 } 333 334 oop ClassLoaderData::keep_alive_object() const { 335 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 336 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 337 } 338 339 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 340 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 341 || is_alive_closure->do_object_b(keep_alive_object()); 342 343 return alive; 344 } 345 346 347 ClassLoaderData::~ClassLoaderData() { 348 // Release C heap structures for all the classes. 349 classes_do(InstanceKlass::release_C_heap_structures); 350 351 Metaspace *m = _metaspace; 352 if (m != NULL) { 353 _metaspace = NULL; 354 // release the metaspace 355 delete m; 356 // release the handles 357 if (_handles != NULL) { 358 JNIHandleBlock::release_block(_handles); 359 _handles = NULL; 360 } 361 } 362 363 // Clear all the JNI handles for methods 364 // These aren't deallocated and are going to look like a leak, but that's 365 // needed because we can't really get rid of jmethodIDs because we don't 366 // know when native code is going to stop using them. The spec says that 367 // they're "invalid" but existing programs likely rely on their being 368 // NULL after class unloading. 369 if (_jmethod_ids != NULL) { 370 Method::clear_jmethod_ids(this); 371 } 372 // Delete lock 373 delete _metaspace_lock; 374 375 // Delete free list 376 if (_deallocate_list != NULL) { 377 delete _deallocate_list; 378 } 379 } 380 381 /** 382 * Returns true if this class loader data is for the extension class loader. 383 */ 384 bool ClassLoaderData::is_ext_class_loader_data() const { 385 return SystemDictionary::is_ext_class_loader(class_loader()); 386 } 387 388 Metaspace* ClassLoaderData::metaspace_non_null() { 389 assert(!DumpSharedSpaces, "wrong metaspace!"); 390 // If the metaspace has not been allocated, create a new one. Might want 391 // to create smaller arena for Reflection class loaders also. 392 // The reason for the delayed allocation is because some class loaders are 393 // simply for delegating with no metadata of their own. 394 if (_metaspace == NULL) { 395 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 396 // Check again if metaspace has been allocated while we were getting this lock. 397 if (_metaspace != NULL) { 398 return _metaspace; 399 } 400 if (this == the_null_class_loader_data()) { 401 assert (class_loader() == NULL, "Must be"); 402 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType)); 403 } else if (is_anonymous()) { 404 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 405 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name()); 406 } 407 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType)); 408 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 409 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 410 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name()); 411 } 412 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType)); 413 } else { 414 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType)); 415 } 416 } 417 return _metaspace; 418 } 419 420 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 421 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 422 423 jobject ClassLoaderData::add_handle(Handle h) { 424 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 425 if (handles() == NULL) { 426 set_handles(JNIHandleBlock::allocate_block()); 427 } 428 return handles()->allocate_handle(h()); 429 } 430 431 // Add this metadata pointer to be freed when it's safe. This is only during 432 // class unloading because Handles might point to this metadata field. 433 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 434 // Metadata in shared region isn't deleted. 435 if (!m->is_shared()) { 436 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 437 if (_deallocate_list == NULL) { 438 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 439 } 440 _deallocate_list->append_if_missing(m); 441 } 442 } 443 444 // Deallocate free metadata on the free list. How useful the PermGen was! 445 void ClassLoaderData::free_deallocate_list() { 446 // Don't need lock, at safepoint 447 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 448 if (_deallocate_list == NULL) { 449 return; 450 } 451 // Go backwards because this removes entries that are freed. 452 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 453 Metadata* m = _deallocate_list->at(i); 454 if (!m->on_stack()) { 455 _deallocate_list->remove_at(i); 456 // There are only three types of metadata that we deallocate directly. 457 // Cast them so they can be used by the template function. 458 if (m->is_method()) { 459 MetadataFactory::free_metadata(this, (Method*)m); 460 } else if (m->is_constantPool()) { 461 MetadataFactory::free_metadata(this, (ConstantPool*)m); 462 } else if (m->is_klass()) { 463 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 464 } else { 465 ShouldNotReachHere(); 466 } 467 } 468 } 469 } 470 471 // These anonymous class loaders are to contain classes used for JSR292 472 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 473 // Add a new class loader data to the graph. 474 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL); 475 } 476 477 const char* ClassLoaderData::loader_name() { 478 // Handles null class loader 479 return SystemDictionary::loader_name(class_loader()); 480 } 481 482 #ifndef PRODUCT 483 // Define to dump klasses 484 #undef CLD_DUMP_KLASSES 485 486 void ClassLoaderData::dump(outputStream * const out) { 487 ResourceMark rm; 488 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {", 489 p2i(this), p2i((void *)class_loader()), 490 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 491 if (claimed()) out->print(" claimed "); 492 if (is_unloading()) out->print(" unloading "); 493 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 494 out->cr(); 495 if (metaspace_or_null() != NULL) { 496 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 497 metaspace_or_null()->dump(out); 498 } else { 499 out->print_cr("metaspace: NULL"); 500 } 501 502 #ifdef CLD_DUMP_KLASSES 503 if (Verbose) { 504 ResourceMark rm; 505 Klass* k = _klasses; 506 while (k != NULL) { 507 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 508 k->has_modified_oops(), k->has_accumulated_modified_oops()); 509 assert(k != k->next_link(), "no loops!"); 510 k = k->next_link(); 511 } 512 } 513 #endif // CLD_DUMP_KLASSES 514 #undef CLD_DUMP_KLASSES 515 if (_jmethod_ids != NULL) { 516 Method::print_jmethod_ids(this, out); 517 } 518 out->print_cr("}"); 519 } 520 #endif // PRODUCT 521 522 void ClassLoaderData::verify() { 523 oop cl = class_loader(); 524 525 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 526 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 527 528 // Verify the integrity of the allocated space. 529 if (metaspace_or_null() != NULL) { 530 metaspace_or_null()->verify(); 531 } 532 533 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 534 guarantee(k->class_loader_data() == this, "Must be the same"); 535 k->verify(); 536 assert(k != k->next_link(), "no loops!"); 537 } 538 } 539 540 bool ClassLoaderData::contains_klass(Klass* klass) { 541 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 542 if (k == klass) return true; 543 } 544 return false; 545 } 546 547 548 // GC root of class loader data created. 549 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 550 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 551 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 552 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 553 554 bool ClassLoaderDataGraph::_should_purge = false; 555 bool ClassLoaderDataGraph::_metaspace_oom = false; 556 557 // Add a new class loader data node to the list. Assign the newly created 558 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 559 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 560 // We need to allocate all the oops for the ClassLoaderData before allocating the 561 // actual ClassLoaderData object. 562 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 563 564 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the 565 // ClassLoaderData in the graph since the CLD 566 // contains unhandled oops 567 568 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 569 570 571 if (!is_anonymous) { 572 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 573 // First, Atomically set it 574 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 575 if (old != NULL) { 576 delete cld; 577 // Returns the data. 578 return old; 579 } 580 } 581 582 // We won the race, and therefore the task of adding the data to the list of 583 // class loader data 584 ClassLoaderData** list_head = &_head; 585 ClassLoaderData* next = _head; 586 587 do { 588 cld->set_next(next); 589 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 590 if (exchanged == next) { 591 if (TraceClassLoaderData) { 592 ResourceMark rm; 593 tty->print("[ClassLoaderData: "); 594 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 595 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 596 cld->loader_name()); 597 tty->print_cr("]"); 598 } 599 return cld; 600 } 601 next = exchanged; 602 } while (true); 603 604 } 605 606 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 607 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 608 cld->oops_do(f, klass_closure, must_claim); 609 } 610 } 611 612 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 613 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 614 if (cld->keep_alive()) { 615 cld->oops_do(f, klass_closure, must_claim); 616 } 617 } 618 } 619 620 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 621 if (ClassUnloading) { 622 keep_alive_oops_do(f, klass_closure, must_claim); 623 } else { 624 oops_do(f, klass_closure, must_claim); 625 } 626 } 627 628 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 629 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 630 cl->do_cld(cld); 631 } 632 } 633 634 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 635 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 636 CLDClosure* closure = cld->keep_alive() ? strong : weak; 637 if (closure != NULL) { 638 closure->do_cld(cld); 639 } 640 } 641 } 642 643 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 644 roots_cld_do(cl, NULL); 645 } 646 647 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 648 if (ClassUnloading) { 649 keep_alive_cld_do(cl); 650 } else { 651 cld_do(cl); 652 } 653 } 654 655 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 656 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 657 cld->classes_do(klass_closure); 658 } 659 } 660 661 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 662 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 663 cld->classes_do(f); 664 } 665 } 666 667 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 668 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 669 cld->methods_do(f); 670 } 671 } 672 673 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 674 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 675 cld->loaded_classes_do(klass_closure); 676 } 677 } 678 679 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 680 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 681 // Only walk the head until any clds not purged from prior unloading 682 // (CMS doesn't purge right away). 683 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 684 cld->classes_do(f); 685 } 686 } 687 688 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 689 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 690 691 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 692 693 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 694 ClassLoaderData* curr = _head; 695 while (curr != _saved_head) { 696 if (!curr->claimed()) { 697 array->push(curr); 698 699 if (TraceClassLoaderData) { 700 tty->print("[ClassLoaderData] found new CLD: "); 701 curr->print_value_on(tty); 702 tty->cr(); 703 } 704 } 705 706 curr = curr->_next; 707 } 708 709 return array; 710 } 711 712 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 713 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 714 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 715 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 716 return true; 717 } 718 } 719 return false; 720 } 721 722 #ifndef PRODUCT 723 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 724 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 725 if (loader_data == data) { 726 return true; 727 } 728 } 729 730 return false; 731 } 732 #endif // PRODUCT 733 734 735 // Move class loader data from main list to the unloaded list for unloading 736 // and deallocation later. 737 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) { 738 ClassLoaderData* data = _head; 739 ClassLoaderData* prev = NULL; 740 bool seen_dead_loader = false; 741 742 // Save previous _unloading pointer for CMS which may add to unloading list before 743 // purging and we don't want to rewalk the previously unloaded class loader data. 744 _saved_unloading = _unloading; 745 746 data = _head; 747 while (data != NULL) { 748 if (data->is_alive(is_alive_closure)) { 749 prev = data; 750 data = data->next(); 751 continue; 752 } 753 seen_dead_loader = true; 754 ClassLoaderData* dead = data; 755 dead->unload(); 756 data = data->next(); 757 // Remove from loader list. 758 // This class loader data will no longer be found 759 // in the ClassLoaderDataGraph. 760 if (prev != NULL) { 761 prev->set_next(data); 762 } else { 763 assert(dead == _head, "sanity check"); 764 _head = data; 765 } 766 dead->set_next(_unloading); 767 _unloading = dead; 768 } 769 770 if (clean_alive) { 771 // Clean previous versions and the deallocate list. 772 ClassLoaderDataGraph::clean_metaspaces(); 773 } 774 775 if (seen_dead_loader) { 776 post_class_unload_events(); 777 } 778 779 return seen_dead_loader; 780 } 781 782 void ClassLoaderDataGraph::clean_metaspaces() { 783 // mark metadata seen on the stack and code cache so we can delete unneeded entries. 784 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class(); 785 MetadataOnStackMark md_on_stack(has_redefined_a_class); 786 787 if (has_redefined_a_class) { 788 // purge_previous_versions also cleans weak method links. Because 789 // one method's MDO can reference another method from another 790 // class loader, we need to first clean weak method links for all 791 // class loaders here. Below, we can then free redefined methods 792 // for all class loaders. 793 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 794 data->classes_do(InstanceKlass::purge_previous_versions); 795 } 796 } 797 798 // Need to purge the previous version before deallocating. 799 free_deallocate_lists(); 800 } 801 802 void ClassLoaderDataGraph::purge() { 803 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 804 ClassLoaderData* list = _unloading; 805 _unloading = NULL; 806 ClassLoaderData* next = list; 807 bool classes_unloaded = false; 808 while (next != NULL) { 809 ClassLoaderData* purge_me = next; 810 next = purge_me->next(); 811 delete purge_me; 812 classes_unloaded = true; 813 } 814 if (classes_unloaded) { 815 Metaspace::purge(); 816 set_metaspace_oom(false); 817 } 818 } 819 820 void ClassLoaderDataGraph::post_class_unload_events(void) { 821 #if INCLUDE_TRACE 822 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 823 if (Tracing::enabled()) { 824 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 825 assert(_unloading != NULL, "need class loader data unload list!"); 826 _class_unload_time = Ticks::now(); 827 classes_unloading_do(&class_unload_event); 828 } 829 Tracing::on_unloading_classes(); 830 } 831 #endif 832 } 833 834 void ClassLoaderDataGraph::free_deallocate_lists() { 835 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 836 // We need to keep this data until InstanceKlass::purge_previous_version has been 837 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces. 838 cld->free_deallocate_list(); 839 } 840 } 841 842 // CDS support 843 844 // Global metaspaces for writing information to the shared archive. When 845 // application CDS is supported, we may need one per metaspace, so this 846 // sort of looks like it. 847 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 848 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 849 static bool _shared_metaspaces_initialized = false; 850 851 // Initialize shared metaspaces (change to call from somewhere not lazily) 852 void ClassLoaderData::initialize_shared_metaspaces() { 853 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 854 assert(this == ClassLoaderData::the_null_class_loader_data(), 855 "only supported for null loader data for now"); 856 assert (!_shared_metaspaces_initialized, "only initialize once"); 857 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 858 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 859 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 860 _shared_metaspaces_initialized = true; 861 } 862 863 Metaspace* ClassLoaderData::ro_metaspace() { 864 assert(_ro_metaspace != NULL, "should already be initialized"); 865 return _ro_metaspace; 866 } 867 868 Metaspace* ClassLoaderData::rw_metaspace() { 869 assert(_rw_metaspace != NULL, "should already be initialized"); 870 return _rw_metaspace; 871 } 872 873 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 874 : _next_klass(NULL) { 875 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 876 Klass* klass = NULL; 877 878 // Find the first klass in the CLDG. 879 while (cld != NULL) { 880 klass = cld->_klasses; 881 if (klass != NULL) { 882 _next_klass = klass; 883 return; 884 } 885 cld = cld->next(); 886 } 887 } 888 889 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 890 Klass* next = klass->next_link(); 891 if (next != NULL) { 892 return next; 893 } 894 895 // No more klasses in the current CLD. Time to find a new CLD. 896 ClassLoaderData* cld = klass->class_loader_data(); 897 while (next == NULL) { 898 cld = cld->next(); 899 if (cld == NULL) { 900 break; 901 } 902 next = cld->_klasses; 903 } 904 905 return next; 906 } 907 908 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 909 Klass* head = (Klass*)_next_klass; 910 911 while (head != NULL) { 912 Klass* next = next_klass_in_cldg(head); 913 914 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 915 916 if (old_head == head) { 917 return head; // Won the CAS. 918 } 919 920 head = old_head; 921 } 922 923 // Nothing more for the iterator to hand out. 924 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head))); 925 return NULL; 926 } 927 928 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 929 _data = ClassLoaderDataGraph::_head; 930 } 931 932 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 933 934 #ifndef PRODUCT 935 // callable from debugger 936 extern "C" int print_loader_data_graph() { 937 ClassLoaderDataGraph::dump_on(tty); 938 return 0; 939 } 940 941 void ClassLoaderDataGraph::verify() { 942 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 943 data->verify(); 944 } 945 } 946 947 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 948 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 949 data->dump(out); 950 } 951 MetaspaceAux::dump(out); 952 } 953 #endif // PRODUCT 954 955 void ClassLoaderData::print_value_on(outputStream* out) const { 956 if (class_loader() == NULL) { 957 out->print("NULL class_loader"); 958 } else { 959 out->print("class loader " INTPTR_FORMAT, p2i(this)); 960 class_loader()->print_value_on(out); 961 } 962 } 963 964 #if INCLUDE_TRACE 965 966 Ticks ClassLoaderDataGraph::_class_unload_time; 967 968 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 969 970 // post class unload event 971 EventClassUnload event(UNTIMED); 972 event.set_endtime(_class_unload_time); 973 event.set_unloadedClass(k); 974 oop defining_class_loader = k->class_loader(); 975 event.set_definingClassLoader(defining_class_loader != NULL ? 976 defining_class_loader->klass() : (Klass*)NULL); 977 event.commit(); 978 } 979 980 #endif // INCLUDE_TRACE