1 /* 2 * Copyright (c) 2012, 2013, 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/systemDictionary.hpp" 54 #include "code/codeCache.hpp" 55 #include "memory/metadataFactory.hpp" 56 #include "memory/metaspaceShared.hpp" 57 #include "prims/jvmtiRedefineClasses.hpp" 58 #include "runtime/jniHandles.hpp" 59 #include "runtime/mutex.hpp" 60 #include "runtime/safepoint.hpp" 61 #include "runtime/synchronizer.hpp" 62 #include "utilities/growableArray.hpp" 63 #include "utilities/ostream.hpp" 64 65 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 66 67 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) : 68 _class_loader(h_class_loader()), 69 _is_anonymous(is_anonymous), _keep_alive(is_anonymous), // initially 70 _metaspace(NULL), _unloading(false), _klasses(NULL), 71 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL), 72 _next(NULL), _dependencies(NULL), 73 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) { 74 // empty 75 } 76 77 void ClassLoaderData::init_dependencies(TRAPS) { 78 // Create empty dependencies array to add to. CMS requires this to be 79 // an oop so that it can track additions via card marks. We think. 80 _dependencies = (oop)oopFactory::new_objectArray(2, CHECK); 81 } 82 83 bool ClassLoaderData::claim() { 84 if (_claimed == 1) { 85 return false; 86 } 87 88 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 89 } 90 91 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 92 if (must_claim && !claim()) { 93 return; 94 } 95 96 f->do_oop(&_class_loader); 97 f->do_oop(&_dependencies); 98 _handles->oops_do(f); 99 if (klass_closure != NULL) { 100 classes_do(klass_closure); 101 } 102 } 103 104 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 105 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 106 klass_closure->do_klass(k); 107 } 108 } 109 110 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 111 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 112 if (k->oop_is_instance()) { 113 f(InstanceKlass::cast(k)); 114 } 115 } 116 } 117 118 void ClassLoaderData::record_dependency(Klass* k, TRAPS) { 119 ClassLoaderData * const from_cld = this; 120 ClassLoaderData * const to_cld = k->class_loader_data(); 121 122 // Dependency to the null class loader data doesn't need to be recorded 123 // because the null class loader data never goes away. 124 if (to_cld->is_the_null_class_loader_data()) { 125 return; 126 } 127 128 oop to; 129 if (to_cld->is_anonymous()) { 130 // Anonymous class dependencies are through the mirror. 131 to = k->java_mirror(); 132 } else { 133 to = to_cld->class_loader(); 134 135 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 136 // we still have to add it. The class_loader won't keep from_cld alive. 137 if (!from_cld->is_anonymous()) { 138 // Check that this dependency isn't from the same or parent class_loader 139 oop from = from_cld->class_loader(); 140 141 oop curr = from; 142 while (curr != NULL) { 143 if (curr == to) { 144 return; // this class loader is in the parent list, no need to add it. 145 } 146 curr = java_lang_ClassLoader::parent(curr); 147 } 148 } 149 } 150 151 // It's a dependency we won't find through GC, add it. This is relatively rare 152 // Must handle over GC point. 153 Handle dependency(THREAD, to); 154 from_cld->add_dependency(dependency, CHECK); 155 } 156 157 158 void ClassLoaderData::add_dependency(Handle dependency, TRAPS) { 159 // Check first if this dependency is already in the list. 160 // Save a pointer to the last to add to under the lock. 161 objArrayOop ok = (objArrayOop)_dependencies; 162 objArrayOop last = NULL; 163 while (ok != NULL) { 164 last = ok; 165 if (ok->obj_at(0) == dependency()) { 166 // Don't need to add it 167 return; 168 } 169 ok = (objArrayOop)ok->obj_at(1); 170 } 171 172 // Must handle over GC points 173 assert (last != NULL, "dependencies should be initialized"); 174 objArrayHandle last_handle(THREAD, last); 175 176 // Create a new dependency node with fields for (class_loader or mirror, next) 177 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 178 deps->obj_at_put(0, dependency()); 179 180 // Must handle over GC points 181 objArrayHandle new_dependency(THREAD, deps); 182 183 // Add the dependency under lock 184 locked_add_dependency(last_handle, new_dependency); 185 } 186 187 void ClassLoaderData::locked_add_dependency(objArrayHandle last_handle, 188 objArrayHandle new_dependency) { 189 190 // Have to lock and put the new dependency on the end of the dependency 191 // array so the card mark for CMS sees that this dependency is new. 192 // Can probably do this lock free with some effort. 193 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 194 195 oop loader_or_mirror = new_dependency->obj_at(0); 196 197 // Since the dependencies are only added, add to the end. 198 objArrayOop end = last_handle(); 199 objArrayOop last = NULL; 200 while (end != NULL) { 201 last = end; 202 // check again if another thread added it to the end. 203 if (end->obj_at(0) == loader_or_mirror) { 204 // Don't need to add it 205 return; 206 } 207 end = (objArrayOop)end->obj_at(1); 208 } 209 assert (last != NULL, "dependencies should be initialized"); 210 // fill in the first element with the oop in new_dependency. 211 if (last->obj_at(0) == NULL) { 212 last->obj_at_put(0, new_dependency->obj_at(0)); 213 } else { 214 last->obj_at_put(1, new_dependency()); 215 } 216 } 217 218 void ClassLoaderDataGraph::clear_claimed_marks() { 219 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 220 cld->clear_claimed(); 221 } 222 } 223 224 void ClassLoaderData::add_class(Klass* k) { 225 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 226 Klass* old_value = _klasses; 227 k->set_next_link(old_value); 228 // link the new item into the list 229 _klasses = k; 230 231 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) { 232 ResourceMark rm; 233 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: " 234 PTR_FORMAT " loader: " PTR_FORMAT " %s", 235 k, 236 k->external_name(), 237 k->class_loader_data(), 238 k->class_loader(), 239 loader_name()); 240 } 241 } 242 243 // This is called by InstanceKlass::deallocate_contents() to remove the 244 // scratch_class for redefine classes. We need a lock because there it may not 245 // be called at a safepoint if there's an error. 246 void ClassLoaderData::remove_class(Klass* scratch_class) { 247 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 248 Klass* prev = NULL; 249 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 250 if (k == scratch_class) { 251 if (prev == NULL) { 252 _klasses = k->next_link(); 253 } else { 254 Klass* next = k->next_link(); 255 prev->set_next_link(next); 256 } 257 return; 258 } 259 prev = k; 260 } 261 ShouldNotReachHere(); // should have found this class!! 262 } 263 264 void ClassLoaderData::unload() { 265 _unloading = true; 266 267 if (TraceClassLoaderData) { 268 ResourceMark rm; 269 tty->print("[ClassLoaderData: unload loader data "PTR_FORMAT, this); 270 tty->print(" for instance "PTR_FORMAT" of %s", class_loader(), 271 loader_name()); 272 if (is_anonymous()) { 273 tty->print(" for anonymous class "PTR_FORMAT " ", _klasses); 274 } 275 tty->print_cr("]"); 276 } 277 } 278 279 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 280 bool alive = 281 is_anonymous() ? 282 is_alive_closure->do_object_b(_klasses->java_mirror()) : 283 class_loader() == NULL || is_alive_closure->do_object_b(class_loader()); 284 assert(!alive || claimed(), "must be claimed"); 285 return alive; 286 } 287 288 289 ClassLoaderData::~ClassLoaderData() { 290 Metaspace *m = _metaspace; 291 if (m != NULL) { 292 _metaspace = NULL; 293 // release the metaspace 294 delete m; 295 // release the handles 296 if (_handles != NULL) { 297 JNIHandleBlock::release_block(_handles); 298 _handles = NULL; 299 } 300 } 301 302 // Clear all the JNI handles for methods 303 // These aren't deallocated and are going to look like a leak, but that's 304 // needed because we can't really get rid of jmethodIDs because we don't 305 // know when native code is going to stop using them. The spec says that 306 // they're "invalid" but existing programs likely rely on their being 307 // NULL after class unloading. 308 if (_jmethod_ids != NULL) { 309 Method::clear_jmethod_ids(this); 310 } 311 // Delete lock 312 delete _metaspace_lock; 313 314 // Delete free list 315 if (_deallocate_list != NULL) { 316 delete _deallocate_list; 317 } 318 } 319 320 Metaspace* ClassLoaderData::metaspace_non_null() { 321 assert(!DumpSharedSpaces, "wrong metaspace!"); 322 // If the metaspace has not been allocated, create a new one. Might want 323 // to create smaller arena for Reflection class loaders also. 324 // The reason for the delayed allocation is because some class loaders are 325 // simply for delegating with no metadata of their own. 326 if (_metaspace == NULL) { 327 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 328 // Check again if metaspace has been allocated while we were getting this lock. 329 if (_metaspace != NULL) { 330 return _metaspace; 331 } 332 if (this == the_null_class_loader_data()) { 333 assert (class_loader() == NULL, "Must be"); 334 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType)); 335 } else if (is_anonymous()) { 336 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 337 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name()); 338 } 339 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType)); 340 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 341 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 342 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name()); 343 } 344 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType)); 345 } else { 346 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType)); 347 } 348 } 349 return _metaspace; 350 } 351 352 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 353 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 354 355 jobject ClassLoaderData::add_handle(Handle h) { 356 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 357 if (handles() == NULL) { 358 set_handles(JNIHandleBlock::allocate_block()); 359 } 360 return handles()->allocate_handle(h()); 361 } 362 363 // Add this metadata pointer to be freed when it's safe. This is only during 364 // class unloading because Handles might point to this metadata field. 365 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 366 // Metadata in shared region isn't deleted. 367 if (!m->is_shared()) { 368 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 369 if (_deallocate_list == NULL) { 370 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 371 } 372 _deallocate_list->append_if_missing(m); 373 } 374 } 375 376 // Deallocate free metadata on the free list. How useful the PermGen was! 377 void ClassLoaderData::free_deallocate_list() { 378 // Don't need lock, at safepoint 379 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 380 if (_deallocate_list == NULL) { 381 return; 382 } 383 // Go backwards because this removes entries that are freed. 384 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 385 Metadata* m = _deallocate_list->at(i); 386 if (!m->on_stack()) { 387 _deallocate_list->remove_at(i); 388 // There are only three types of metadata that we deallocate directly. 389 // Cast them so they can be used by the template function. 390 if (m->is_method()) { 391 MetadataFactory::free_metadata(this, (Method*)m); 392 } else if (m->is_constantPool()) { 393 MetadataFactory::free_metadata(this, (ConstantPool*)m); 394 } else if (m->is_klass()) { 395 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 396 } else { 397 ShouldNotReachHere(); 398 } 399 } 400 } 401 } 402 403 // These anonymous class loaders are to contain classes used for JSR292 404 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 405 // Add a new class loader data to the graph. 406 return ClassLoaderDataGraph::add(NULL, loader, CHECK_NULL); 407 } 408 409 const char* ClassLoaderData::loader_name() { 410 // Handles null class loader 411 return SystemDictionary::loader_name(class_loader()); 412 } 413 414 #ifndef PRODUCT 415 // Define to dump klasses 416 #undef CLD_DUMP_KLASSES 417 418 void ClassLoaderData::dump(outputStream * const out) { 419 ResourceMark rm; 420 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {", 421 this, class_loader(), 422 class_loader() != NULL ? class_loader()->klass() : NULL, loader_name()); 423 if (claimed()) out->print(" claimed "); 424 if (is_unloading()) out->print(" unloading "); 425 out->print(" handles " INTPTR_FORMAT, handles()); 426 out->cr(); 427 if (metaspace_or_null() != NULL) { 428 out->print_cr("metaspace: " PTR_FORMAT, metaspace_or_null()); 429 metaspace_or_null()->dump(out); 430 } else { 431 out->print_cr("metaspace: NULL"); 432 } 433 434 #ifdef CLD_DUMP_KLASSES 435 if (Verbose) { 436 ResourceMark rm; 437 Klass* k = _klasses; 438 while (k != NULL) { 439 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 440 k->has_modified_oops(), k->has_accumulated_modified_oops()); 441 k = k->next_link(); 442 } 443 } 444 #endif // CLD_DUMP_KLASSES 445 #undef CLD_DUMP_KLASSES 446 if (_jmethod_ids != NULL) { 447 Method::print_jmethod_ids(this, out); 448 } 449 out->print_cr("}"); 450 } 451 #endif // PRODUCT 452 453 void ClassLoaderData::verify() { 454 oop cl = class_loader(); 455 456 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 457 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 458 459 // Verify the integrity of the allocated space. 460 if (metaspace_or_null() != NULL) { 461 metaspace_or_null()->verify(); 462 } 463 464 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 465 guarantee(k->class_loader_data() == this, "Must be the same"); 466 k->verify(); 467 } 468 } 469 470 471 // GC root of class loader data created. 472 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 473 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 474 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 475 476 477 // Add a new class loader data node to the list. Assign the newly created 478 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 479 ClassLoaderData* ClassLoaderDataGraph::add(ClassLoaderData** cld_addr, Handle loader, TRAPS) { 480 // Not assigned a class loader data yet. 481 // Create one. 482 ClassLoaderData* *list_head = &_head; 483 ClassLoaderData* next = _head; 484 485 bool is_anonymous = (cld_addr == NULL); 486 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous); 487 488 if (cld_addr != NULL) { 489 // First, Atomically set it 490 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 491 if (old != NULL) { 492 delete cld; 493 // Returns the data. 494 return old; 495 } 496 } 497 498 // We won the race, and therefore the task of adding the data to the list of 499 // class loader data 500 do { 501 cld->set_next(next); 502 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 503 if (exchanged == next) { 504 if (TraceClassLoaderData) { 505 ResourceMark rm; 506 tty->print("[ClassLoaderData: "); 507 tty->print("create class loader data "PTR_FORMAT, cld); 508 tty->print(" for instance "PTR_FORMAT" of %s", cld->class_loader(), 509 cld->loader_name()); 510 tty->print_cr("]"); 511 } 512 // Create dependencies after the CLD is added to the list. Otherwise, 513 // the GC GC will not find the CLD and the _class_loader field will 514 // not be updated. 515 cld->init_dependencies(CHECK_NULL); 516 return cld; 517 } 518 next = exchanged; 519 } while (true); 520 521 } 522 523 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 524 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 525 cld->oops_do(f, klass_closure, must_claim); 526 } 527 } 528 529 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 530 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 531 if (cld->keep_alive()) { 532 cld->oops_do(f, klass_closure, must_claim); 533 } 534 } 535 } 536 537 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 538 if (ClassUnloading) { 539 ClassLoaderData::the_null_class_loader_data()->oops_do(f, klass_closure, must_claim); 540 // keep any special CLDs alive. 541 ClassLoaderDataGraph::keep_alive_oops_do(f, klass_closure, must_claim); 542 } else { 543 ClassLoaderDataGraph::oops_do(f, klass_closure, must_claim); 544 } 545 } 546 547 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 548 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 549 cld->classes_do(klass_closure); 550 } 551 } 552 553 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 554 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 555 556 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 557 558 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 559 ClassLoaderData* curr = _head; 560 while (curr != _saved_head) { 561 if (!curr->claimed()) { 562 array->push(curr); 563 564 if (TraceClassLoaderData) { 565 tty->print("[ClassLoaderData] found new CLD: "); 566 curr->print_value_on(tty); 567 tty->cr(); 568 } 569 } 570 571 curr = curr->_next; 572 } 573 574 return array; 575 } 576 577 #ifndef PRODUCT 578 // for debugging and hsfind(x) 579 bool ClassLoaderDataGraph::contains(address x) { 580 // I think we need the _metaspace_lock taken here because the class loader 581 // data graph could be changing while we are walking it (new entries added, 582 // new entries being unloaded, etc). 583 if (DumpSharedSpaces) { 584 // There are only two metaspaces to worry about. 585 ClassLoaderData* ncld = ClassLoaderData::the_null_class_loader_data(); 586 return (ncld->ro_metaspace()->contains(x) || ncld->rw_metaspace()->contains(x)); 587 } 588 589 if (UseSharedSpaces && MetaspaceShared::is_in_shared_space(x)) { 590 return true; 591 } 592 593 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 594 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 595 return true; 596 } 597 } 598 599 // Could also be on an unloading list which is okay, ie. still allocated 600 // for a little while. 601 for (ClassLoaderData* ucld = _unloading; ucld != NULL; ucld = ucld->next()) { 602 if (ucld->metaspace_or_null() != NULL && ucld->metaspace_or_null()->contains(x)) { 603 return true; 604 } 605 } 606 return false; 607 } 608 609 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 610 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 611 if (loader_data == data) { 612 return true; 613 } 614 } 615 616 return false; 617 } 618 #endif // PRODUCT 619 620 621 // Move class loader data from main list to the unloaded list for unloading 622 // and deallocation later. 623 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) { 624 ClassLoaderData* data = _head; 625 ClassLoaderData* prev = NULL; 626 bool seen_dead_loader = false; 627 // mark metadata seen on the stack and code cache so we can delete 628 // unneeded entries. 629 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class(); 630 MetadataOnStackMark md_on_stack; 631 while (data != NULL) { 632 if (data->keep_alive() || data->is_alive(is_alive_closure)) { 633 if (has_redefined_a_class) { 634 data->classes_do(InstanceKlass::purge_previous_versions); 635 } 636 data->free_deallocate_list(); 637 prev = data; 638 data = data->next(); 639 continue; 640 } 641 seen_dead_loader = true; 642 ClassLoaderData* dead = data; 643 dead->unload(); 644 data = data->next(); 645 // Remove from loader list. 646 if (prev != NULL) { 647 prev->set_next(data); 648 } else { 649 assert(dead == _head, "sanity check"); 650 _head = data; 651 } 652 dead->set_next(_unloading); 653 _unloading = dead; 654 } 655 return seen_dead_loader; 656 } 657 658 void ClassLoaderDataGraph::purge() { 659 ClassLoaderData* list = _unloading; 660 _unloading = NULL; 661 ClassLoaderData* next = list; 662 while (next != NULL) { 663 ClassLoaderData* purge_me = next; 664 next = purge_me->next(); 665 delete purge_me; 666 } 667 } 668 669 // CDS support 670 671 // Global metaspaces for writing information to the shared archive. When 672 // application CDS is supported, we may need one per metaspace, so this 673 // sort of looks like it. 674 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 675 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 676 static bool _shared_metaspaces_initialized = false; 677 678 // Initialize shared metaspaces (change to call from somewhere not lazily) 679 void ClassLoaderData::initialize_shared_metaspaces() { 680 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 681 assert(this == ClassLoaderData::the_null_class_loader_data(), 682 "only supported for null loader data for now"); 683 assert (!_shared_metaspaces_initialized, "only initialize once"); 684 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 685 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 686 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 687 _shared_metaspaces_initialized = true; 688 } 689 690 Metaspace* ClassLoaderData::ro_metaspace() { 691 assert(_ro_metaspace != NULL, "should already be initialized"); 692 return _ro_metaspace; 693 } 694 695 Metaspace* ClassLoaderData::rw_metaspace() { 696 assert(_rw_metaspace != NULL, "should already be initialized"); 697 return _rw_metaspace; 698 } 699 700 701 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 702 _data = ClassLoaderDataGraph::_head; 703 } 704 705 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 706 707 #ifndef PRODUCT 708 // callable from debugger 709 extern "C" int print_loader_data_graph() { 710 ClassLoaderDataGraph::dump_on(tty); 711 return 0; 712 } 713 714 void ClassLoaderDataGraph::verify() { 715 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 716 data->verify(); 717 } 718 } 719 720 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 721 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 722 data->dump(out); 723 } 724 MetaspaceAux::dump(out); 725 } 726 #endif // PRODUCT 727 728 void ClassLoaderData::print_value_on(outputStream* out) const { 729 if (class_loader() == NULL) { 730 out->print("NULL class_loader"); 731 } else { 732 out->print("class loader "PTR_FORMAT, this); 733 class_loader()->print_value_on(out); 734 } 735 }