/* * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ // A ClassLoaderData identifies the full set of class types that a class // loader's name resolution strategy produces for a given configuration of the // class loader. // Class types in the ClassLoaderData may be defined by from class file binaries // provided by the class loader, or from other class loader it interacts with // according to its name resolution strategy. // // Class loaders that implement a deterministic name resolution strategy // (including with respect to their delegation behavior), such as the boot, the // platform, and the system loaders of the JDK's built-in class loader // hierarchy, always produce the same linkset for a given configuration. // // ClassLoaderData carries information related to a linkset (e.g., // metaspace holding its klass definitions). // The System Dictionary and related data structures (e.g., placeholder table, // loader constraints table) as well as the runtime representation of classes // only reference ClassLoaderData. // // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that // that represent the loader's "linking domain" in the JVM. // // The bootstrap loader (represented by NULL) also has a ClassLoaderData, // the singleton class the_null_class_loader_data(). #include "precompiled.hpp" #include "classfile/classLoaderData.hpp" #include "classfile/classLoaderData.inline.hpp" #include "classfile/dictionary.hpp" #include "classfile/javaClasses.hpp" #include "classfile/metadataOnStackMark.hpp" #include "classfile/moduleEntry.hpp" #include "classfile/packageEntry.hpp" #include "classfile/systemDictionary.hpp" #include "code/codeCache.hpp" #include "gc/shared/gcLocker.hpp" #include "logging/log.hpp" #include "memory/metadataFactory.hpp" #include "memory/metaspaceShared.hpp" #include "memory/oopFactory.hpp" #include "memory/resourceArea.hpp" #include "oops/objArrayOop.inline.hpp" #include "oops/oop.inline.hpp" #include "runtime/atomic.hpp" #include "runtime/javaCalls.hpp" #include "runtime/jniHandles.hpp" #include "runtime/mutex.hpp" #include "runtime/orderAccess.hpp" #include "runtime/safepoint.hpp" #include "runtime/synchronizer.hpp" #include "utilities/growableArray.hpp" #include "utilities/macros.hpp" #include "utilities/ostream.hpp" #if INCLUDE_TRACE #include "trace/tracing.hpp" #endif // helper function to avoid in-line casts template static T* load_ptr_acquire(T* volatile *p) { return static_cast(OrderAccess::load_ptr_acquire(p)); } ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : _class_loader(h_class_loader()), _is_anonymous(is_anonymous), // An anonymous class loader data doesn't have anything to keep // it from being unloaded during parsing of the anonymous class. // The null-class-loader should always be kept alive. _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), _metaspace(NULL), _unloading(false), _klasses(NULL), _modules(NULL), _packages(NULL), _claimed(0), _jmethod_ids(NULL), _handles(), _deallocate_list(NULL), _next(NULL), _dependencies(dependencies), _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, Monitor::_safepoint_check_never)) { // A ClassLoaderData created solely for an anonymous class should never have a // ModuleEntryTable or PackageEntryTable created for it. The defining package // and module for an anonymous class will be found in its host class. if (!is_anonymous) { _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); if (h_class_loader.is_null()) { // Create unnamed module for boot loader _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); } else { // Create unnamed module for all other loaders _unnamed_module = ModuleEntry::create_unnamed_module(this); } } else { _unnamed_module = NULL; } if (!is_anonymous) { _dictionary = create_dictionary(); } else { _dictionary = NULL; } TRACE_INIT_ID(this); } void ClassLoaderData::init_dependencies(TRAPS) { assert(!Universe::is_fully_initialized(), "should only be called when initializing"); assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); _dependencies.init(CHECK); } void ClassLoaderData::Dependencies::init(TRAPS) { // Create empty dependencies array to add to. CMS requires this to be // an oop so that it can track additions via card marks. We think. _list_head = oopFactory::new_objectArray(2, CHECK); } ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { Chunk* c = _head; while (c != NULL) { Chunk* next = c->_next; delete c; c = next; } } oop* ClassLoaderData::ChunkedHandleList::add(oop o) { if (_head == NULL || _head->_size == Chunk::CAPACITY) { Chunk* next = new Chunk(_head); OrderAccess::release_store_ptr(&_head, next); } oop* handle = &_head->_data[_head->_size]; *handle = o; OrderAccess::release_store(&_head->_size, _head->_size + 1); return handle; } inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { for (juint i = 0; i < size; i++) { if (c->_data[i] != NULL) { f->do_oop(&c->_data[i]); } } } void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head); if (head != NULL) { // Must be careful when reading size of head oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size)); for (Chunk* c = head->_next; c != NULL; c = c->_next) { oops_do_chunk(f, c, c->_size); } } } #ifdef ASSERT class VerifyContainsOopClosure : public OopClosure { oop* _target; bool _found; public: VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {} void do_oop(oop* p) { if (p == _target) { _found = true; } } void do_oop(narrowOop* p) { // The ChunkedHandleList should not contain any narrowOop ShouldNotReachHere(); } bool found() const { return _found; } }; bool ClassLoaderData::ChunkedHandleList::contains(oop* p) { VerifyContainsOopClosure cl(p); oops_do(&cl); return cl.found(); } #endif bool ClassLoaderData::claim() { if (_claimed == 1) { return false; } return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; } // Anonymous classes have their own ClassLoaderData that is marked to keep alive // while the class is being parsed, and if the class appears on the module fixup list. // Due to the uniqueness that no other class shares the anonymous class' name or // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while // it is being defined, therefore _keep_alive is not volatile or atomic. void ClassLoaderData::inc_keep_alive() { if (is_anonymous()) { assert(_keep_alive >= 0, "Invalid keep alive increment count"); _keep_alive++; } } void ClassLoaderData::dec_keep_alive() { if (is_anonymous()) { assert(_keep_alive > 0, "Invalid keep alive decrement count"); _keep_alive--; } } void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { if (must_claim && !claim()) { return; } f->do_oop(&_class_loader); _dependencies.oops_do(f); _handles.oops_do(f); if (klass_closure != NULL) { classes_do(klass_closure); } } void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { f->do_oop((oop*)&_list_head); } void ClassLoaderData::classes_do(KlassClosure* klass_closure) { // Lock-free access requires load_ptr_acquire for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { klass_closure->do_klass(k); assert(k != k->next_link(), "no loops!"); } } void ClassLoaderData::classes_do(void f(Klass * const)) { // Lock-free access requires load_ptr_acquire for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { f(k); assert(k != k->next_link(), "no loops!"); } } void ClassLoaderData::methods_do(void f(Method*)) { // Lock-free access requires load_ptr_acquire for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { InstanceKlass::cast(k)->methods_do(f); } } } void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { // Lock-free access requires load_ptr_acquire for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { // Do not filter ArrayKlass oops here... if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { klass_closure->do_klass(k); } } } void ClassLoaderData::classes_do(void f(InstanceKlass*)) { // Lock-free access requires load_ptr_acquire for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { if (k->is_instance_klass()) { f(InstanceKlass::cast(k)); } assert(k != k->next_link(), "no loops!"); } } void ClassLoaderData::modules_do(void f(ModuleEntry*)) { assert_locked_or_safepoint(Module_lock); if (_unnamed_module != NULL) { f(_unnamed_module); } if (_modules != NULL) { for (int i = 0; i < _modules->table_size(); i++) { for (ModuleEntry* entry = _modules->bucket(i); entry != NULL; entry = entry->next()) { f(entry); } } } } void ClassLoaderData::packages_do(void f(PackageEntry*)) { assert_locked_or_safepoint(Module_lock); if (_packages != NULL) { for (int i = 0; i < _packages->table_size(); i++) { for (PackageEntry* entry = _packages->bucket(i); entry != NULL; entry = entry->next()) { f(entry); } } } } void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { assert(k != NULL, "invariant"); ClassLoaderData * const from_cld = this; ClassLoaderData * const to_cld = k->class_loader_data(); // Dependency to the null class loader data doesn't need to be recorded // because the null class loader data never goes away. if (to_cld->is_the_null_class_loader_data()) { return; } oop to; if (to_cld->is_anonymous()) { // Anonymous class dependencies are through the mirror. to = k->java_mirror(); } else { to = to_cld->class_loader(); // If from_cld is anonymous, even if it's class_loader is a parent of 'to' // we still have to add it. The class_loader won't keep from_cld alive. if (!from_cld->is_anonymous()) { // Check that this dependency isn't from the same or parent class_loader oop from = from_cld->class_loader(); oop curr = from; while (curr != NULL) { if (curr == to) { return; // this class loader is in the parent list, no need to add it. } curr = java_lang_ClassLoader::parent(curr); } } } // It's a dependency we won't find through GC, add it. This is relatively rare // Must handle over GC point. Handle dependency(THREAD, to); from_cld->_dependencies.add(dependency, CHECK); } void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { // Check first if this dependency is already in the list. // Save a pointer to the last to add to under the lock. objArrayOop ok = _list_head; objArrayOop last = NULL; while (ok != NULL) { last = ok; if (ok->obj_at(0) == dependency()) { // Don't need to add it return; } ok = (objArrayOop)ok->obj_at(1); } // Must handle over GC points assert (last != NULL, "dependencies should be initialized"); objArrayHandle last_handle(THREAD, last); // Create a new dependency node with fields for (class_loader or mirror, next) objArrayOop deps = oopFactory::new_objectArray(2, CHECK); deps->obj_at_put(0, dependency()); // Must handle over GC points objArrayHandle new_dependency(THREAD, deps); // Add the dependency under lock locked_add(last_handle, new_dependency, THREAD); } void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, objArrayHandle new_dependency, Thread* THREAD) { // Have to lock and put the new dependency on the end of the dependency // array so the card mark for CMS sees that this dependency is new. // Can probably do this lock free with some effort. ObjectLocker ol(Handle(THREAD, _list_head), THREAD); oop loader_or_mirror = new_dependency->obj_at(0); // Since the dependencies are only added, add to the end. objArrayOop end = last_handle(); objArrayOop last = NULL; while (end != NULL) { last = end; // check again if another thread added it to the end. if (end->obj_at(0) == loader_or_mirror) { // Don't need to add it return; } end = (objArrayOop)end->obj_at(1); } assert (last != NULL, "dependencies should be initialized"); // fill in the first element with the oop in new_dependency. if (last->obj_at(0) == NULL) { last->obj_at_put(0, new_dependency->obj_at(0)); } else { last->obj_at_put(1, new_dependency()); } } void ClassLoaderDataGraph::clear_claimed_marks() { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->clear_claimed(); } } void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { { MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); Klass* old_value = _klasses; k->set_next_link(old_value); // Link the new item into the list, making sure the linked class is stable // since the list can be walked without a lock OrderAccess::release_store_ptr(&_klasses, k); } if (publicize && k->class_loader_data() != NULL) { ResourceMark rm; log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: " PTR_FORMAT " loader: " PTR_FORMAT " %s", p2i(k), k->external_name(), p2i(k->class_loader_data()), p2i((void *)k->class_loader()), loader_name()); } } // Class iterator used by the compiler. It gets some number of classes at // a safepoint to decay invocation counters on the methods. class ClassLoaderDataGraphKlassIteratorStatic { ClassLoaderData* _current_loader_data; Klass* _current_class_entry; public: ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {} InstanceKlass* try_get_next_class() { assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); while (true) { if (_current_class_entry != NULL) { Klass* k = _current_class_entry; _current_class_entry = _current_class_entry->next_link(); if (k->is_instance_klass()) { InstanceKlass* ik = InstanceKlass::cast(k); // Only return loaded classes if (ik->is_loaded()) { return ik; } } } else { // Go to next CLD if (_current_loader_data != NULL) { _current_loader_data = _current_loader_data->next(); } // Start at the beginning if (_current_loader_data == NULL) { _current_loader_data = ClassLoaderDataGraph::_head; } _current_class_entry = _current_loader_data->klasses(); } } // never reached: an InstanceKlass should be returned above } // If the current class for the static iterator is a class being unloaded or // deallocated, adjust the current class. void adjust_saved_class(ClassLoaderData* cld) { if (_current_loader_data == cld) { _current_loader_data = cld->next(); if (_current_loader_data != NULL) { _current_class_entry = _current_loader_data->klasses(); } // else try_get_next_class will start at the head } } void adjust_saved_class(Klass* klass) { if (_current_class_entry == klass) { _current_class_entry = klass->next_link(); } } }; static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator; InstanceKlass* ClassLoaderDataGraph::try_get_next_class() { return static_klass_iterator.try_get_next_class(); } // Remove a klass from the _klasses list for scratch_class during redefinition // or parsed class in the case of an error. void ClassLoaderData::remove_class(Klass* scratch_class) { assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); // Adjust global class iterator. static_klass_iterator.adjust_saved_class(scratch_class); Klass* prev = NULL; for (Klass* k = _klasses; k != NULL; k = k->next_link()) { if (k == scratch_class) { if (prev == NULL) { _klasses = k->next_link(); } else { Klass* next = k->next_link(); prev->set_next_link(next); } return; } prev = k; assert(k != k->next_link(), "no loops!"); } ShouldNotReachHere(); // should have found this class!! } void ClassLoaderData::unload() { _unloading = true; // Tell serviceability tools these classes are unloading classes_do(InstanceKlass::notify_unload_class); if (log_is_enabled(Debug, class, loader, data)) { ResourceMark rm; outputStream* log = Log(class, loader, data)::debug_stream(); log->print(": unload loader data " INTPTR_FORMAT, p2i(this)); log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), loader_name()); if (is_anonymous()) { log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); } log->cr(); } // In some rare cases items added to this list will not be freed elsewhere. // To keep it simple, just free everything in it here. free_deallocate_list(); // Clean up global class iterator for compiler static_klass_iterator.adjust_saved_class(this); } ModuleEntryTable* ClassLoaderData::modules() { // Lazily create the module entry table at first request. // Lock-free access requires load_ptr_acquire. ModuleEntryTable* modules = load_ptr_acquire(&_modules); if (modules == NULL) { MutexLocker m1(Module_lock); // Check if _modules got allocated while we were waiting for this lock. if ((modules = _modules) == NULL) { modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); { MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); // Ensure _modules is stable, since it is examined without a lock OrderAccess::release_store_ptr(&_modules, modules); } } } return modules; } const int _boot_loader_dictionary_size = 1009; const int _prime_array_size = 8; // array of primes for system dictionary size const int _average_depth_goal = 3; // goal for lookup length const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423}; // Calculate a "good" dictionary size based // on predicted or current loaded classes count *per class loader* // This size will be used for all class loaders if specified, // except boot loader and reflection class loaders static int calculate_dictionary_size(int classcount) { static int newsize = 0; // only calculate once if (newsize != 0) { return newsize; } newsize = _primelist[0]; if (classcount > 0 && !DumpSharedSpaces) { int index = 0; int desiredsize = classcount/_average_depth_goal; for (newsize = _primelist[index]; index < _prime_array_size -1; newsize = _primelist[++index]) { if (desiredsize <= newsize) { break; } } } return newsize; } Dictionary* ClassLoaderData::create_dictionary() { assert(!is_anonymous(), "anonymous class loader data do not have a dictionary"); int size; if (_the_null_class_loader_data == NULL) { size = _boot_loader_dictionary_size; } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { size = 1; // there's only one class in relection class loader and no initiated classes } else { size = calculate_dictionary_size(PredictedLoadedClassCount); } return new Dictionary(this, size); } // Unloading support oop ClassLoaderData::keep_alive_object() const { assert_locked_or_safepoint(_metaspace_lock); assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); return is_anonymous() ? _klasses->java_mirror() : class_loader(); } bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { bool alive = keep_alive() // null class loader and incomplete anonymous klasses. || is_alive_closure->do_object_b(keep_alive_object()); return alive; } ClassLoaderData::~ClassLoaderData() { // Release C heap structures for all the classes. classes_do(InstanceKlass::release_C_heap_structures); // Release C heap allocated hashtable for all the packages. if (_packages != NULL) { // Destroy the table itself delete _packages; _packages = NULL; } // Release C heap allocated hashtable for all the modules. if (_modules != NULL) { // Destroy the table itself delete _modules; _modules = NULL; } // Release C heap allocated hashtable for the dictionary if (_dictionary != NULL) { // Destroy the table itself delete _dictionary; _dictionary = NULL; } if (_unnamed_module != NULL) { _unnamed_module->delete_unnamed_module(); _unnamed_module = NULL; } // release the metaspace Metaspace *m = _metaspace; if (m != NULL) { _metaspace = NULL; delete m; } // Clear all the JNI handles for methods // These aren't deallocated and are going to look like a leak, but that's // needed because we can't really get rid of jmethodIDs because we don't // know when native code is going to stop using them. The spec says that // they're "invalid" but existing programs likely rely on their being // NULL after class unloading. if (_jmethod_ids != NULL) { Method::clear_jmethod_ids(this); } // Delete lock delete _metaspace_lock; // Delete free list if (_deallocate_list != NULL) { delete _deallocate_list; } } // Returns true if this class loader data is for the system class loader. bool ClassLoaderData::is_system_class_loader_data() const { return SystemDictionary::is_system_class_loader(class_loader()); } // Returns true if this class loader data is for the platform class loader. bool ClassLoaderData::is_platform_class_loader_data() const { return SystemDictionary::is_platform_class_loader(class_loader()); } // Returns true if this class loader data is one of the 3 builtin // (boot, application/system or platform) class loaders. Note, the // builtin loaders are not freed by a GC. bool ClassLoaderData::is_builtin_class_loader_data() const { return (is_the_null_class_loader_data() || SystemDictionary::is_system_class_loader(class_loader()) || SystemDictionary::is_platform_class_loader(class_loader())); } Metaspace* ClassLoaderData::metaspace_non_null() { assert(!DumpSharedSpaces, "wrong metaspace!"); // If the metaspace has not been allocated, create a new one. Might want // to create smaller arena for Reflection class loaders also. // The reason for the delayed allocation is because some class loaders are // simply for delegating with no metadata of their own. // Lock-free access requires load_ptr_acquire. Metaspace* metaspace = load_ptr_acquire(&_metaspace); if (metaspace == NULL) { MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); // Check if _metaspace got allocated while we were waiting for this lock. if ((metaspace = _metaspace) == NULL) { if (this == the_null_class_loader_data()) { assert (class_loader() == NULL, "Must be"); metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType); } else if (is_anonymous()) { if (class_loader() != NULL) { log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name()); } metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { if (class_loader() != NULL) { log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name()); } metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); } else { metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); } // Ensure _metaspace is stable, since it is examined without a lock OrderAccess::release_store_ptr(&_metaspace, metaspace); } } return metaspace; } jobject ClassLoaderData::add_handle(Handle h) { MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); return (jobject) _handles.add(h()); } void ClassLoaderData::remove_handle_unsafe(jobject h) { assert(_handles.contains((oop*) h), "Got unexpected handle " PTR_FORMAT, p2i((oop*) h)); *((oop*) h) = NULL; } // Add this metadata pointer to be freed when it's safe. This is only during // class unloading because Handles might point to this metadata field. void ClassLoaderData::add_to_deallocate_list(Metadata* m) { // Metadata in shared region isn't deleted. if (!m->is_shared()) { MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); if (_deallocate_list == NULL) { _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray(100, true); } _deallocate_list->append_if_missing(m); } } // Deallocate free metadata on the free list. How useful the PermGen was! void ClassLoaderData::free_deallocate_list() { // Don't need lock, at safepoint assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); if (_deallocate_list == NULL) { return; } // Go backwards because this removes entries that are freed. for (int i = _deallocate_list->length() - 1; i >= 0; i--) { Metadata* m = _deallocate_list->at(i); if (!m->on_stack()) { _deallocate_list->remove_at(i); // There are only three types of metadata that we deallocate directly. // Cast them so they can be used by the template function. if (m->is_method()) { MetadataFactory::free_metadata(this, (Method*)m); } else if (m->is_constantPool()) { MetadataFactory::free_metadata(this, (ConstantPool*)m); } else if (m->is_klass()) { MetadataFactory::free_metadata(this, (InstanceKlass*)m); } else { ShouldNotReachHere(); } } else { // Metadata is alive. // If scratch_class is on stack then it shouldn't be on this list! assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), "scratch classes on this list should be dead"); // Also should assert that other metadata on the list was found in handles. } } } // These anonymous class loaders are to contain classes used for JSR292 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { // Add a new class loader data to the graph. Handle lh(THREAD, loader); return ClassLoaderDataGraph::add(lh, true, THREAD); } const char* ClassLoaderData::loader_name() { // Handles null class loader return SystemDictionary::loader_name(class_loader()); } #ifndef PRODUCT // Define to dump klasses #undef CLD_DUMP_KLASSES void ClassLoaderData::dump(outputStream * const out) { out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", p2i(this), p2i((void *)class_loader()), p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); if (claimed()) out->print(" claimed "); if (is_unloading()) out->print(" unloading "); out->cr(); if (metaspace_or_null() != NULL) { out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); metaspace_or_null()->dump(out); } else { out->print_cr("metaspace: NULL"); } #ifdef CLD_DUMP_KLASSES if (Verbose) { Klass* k = _klasses; while (k != NULL) { out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), k->has_modified_oops(), k->has_accumulated_modified_oops()); assert(k != k->next_link(), "no loops!"); k = k->next_link(); } } #endif // CLD_DUMP_KLASSES #undef CLD_DUMP_KLASSES if (_jmethod_ids != NULL) { Method::print_jmethod_ids(this, out); } out->print_cr("}"); } #endif // PRODUCT void ClassLoaderData::verify() { assert_locked_or_safepoint(_metaspace_lock); oop cl = class_loader(); guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); // Verify the integrity of the allocated space. if (metaspace_or_null() != NULL) { metaspace_or_null()->verify(); } for (Klass* k = _klasses; k != NULL; k = k->next_link()) { guarantee(k->class_loader_data() == this, "Must be the same"); k->verify(); assert(k != k->next_link(), "no loops!"); } } bool ClassLoaderData::contains_klass(Klass* klass) { // Lock-free access requires load_ptr_acquire for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { if (k == klass) return true; } return false; } // GC root of class loader data created. ClassLoaderData* ClassLoaderDataGraph::_head = NULL; ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; bool ClassLoaderDataGraph::_should_purge = false; bool ClassLoaderDataGraph::_metaspace_oom = false; // Add a new class loader data node to the list. Assign the newly created // ClassLoaderData into the java/lang/ClassLoader object as a hidden field ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { // We need to allocate all the oops for the ClassLoaderData before allocating the // actual ClassLoaderData object. ClassLoaderData::Dependencies dependencies(CHECK_NULL); NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the // ClassLoaderData in the graph since the CLD // contains unhandled oops ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); if (!is_anonymous) { ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); // First, Atomically set it ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); if (old != NULL) { delete cld; // Returns the data. return old; } } // We won the race, and therefore the task of adding the data to the list of // class loader data ClassLoaderData** list_head = &_head; ClassLoaderData* next = _head; do { cld->set_next(next); ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); if (exchanged == next) { if (log_is_enabled(Debug, class, loader, data)) { PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual log_creation(loader, cld, CHECK_NULL); } return cld; } next = exchanged; } while (true); } void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) { Handle string; if (loader.not_null()) { // Include the result of loader.toString() in the output. This allows // the user of the log to identify the class loader instance. JavaValue result(T_OBJECT); Klass* spec_klass = SystemDictionary::ClassLoader_klass(); JavaCalls::call_virtual(&result, loader, spec_klass, vmSymbols::toString_name(), vmSymbols::void_string_signature(), CHECK); assert(result.get_type() == T_OBJECT, "just checking"); string = Handle(THREAD, (oop)result.get_jobject()); } ResourceMark rm; outputStream* log = Log(class, loader, data)::debug_stream(); log->print("create class loader data " INTPTR_FORMAT, p2i(cld)); log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), cld->loader_name()); if (string.not_null()) { log->print(": "); java_lang_String::print(string(), log); } log->cr(); } void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->oops_do(f, klass_closure, must_claim); } } void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { if (cld->keep_alive()) { cld->oops_do(f, klass_closure, must_claim); } } } void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { if (ClassUnloading) { keep_alive_oops_do(f, klass_closure, must_claim); } else { oops_do(f, klass_closure, must_claim); } } void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { cl->do_cld(cld); } } void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) { assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); // Only walk the head until any clds not purged from prior unloading // (CMS doesn't purge right away). for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { assert(cld->is_unloading(), "invariant"); cl->do_cld(cld); } } void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { CLDClosure* closure = cld->keep_alive() ? strong : weak; if (closure != NULL) { closure->do_cld(cld); } } } void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { roots_cld_do(cl, NULL); } void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { if (ClassUnloading) { keep_alive_cld_do(cl); } else { cld_do(cl); } } void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->classes_do(klass_closure); } } void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->classes_do(f); } } void ClassLoaderDataGraph::methods_do(void f(Method*)) { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->methods_do(f); } } void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { assert_locked_or_safepoint(Module_lock); for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->modules_do(f); } } void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); // Only walk the head until any clds not purged from prior unloading // (CMS doesn't purge right away). for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { assert(cld->is_unloading(), "invariant"); cld->modules_do(f); } } void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { assert_locked_or_safepoint(Module_lock); for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->packages_do(f); } } void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); // Only walk the head until any clds not purged from prior unloading // (CMS doesn't purge right away). for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { assert(cld->is_unloading(), "invariant"); cld->packages_do(f); } } void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { cld->loaded_classes_do(klass_closure); } } void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); // Only walk the head until any clds not purged from prior unloading // (CMS doesn't purge right away). for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { assert(cld->is_unloading(), "invariant"); cld->classes_do(f); } } #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \ if (X->dictionary() != NULL) // Walk classes in the loaded class dictionaries in various forms. // Only walks the classes defined in this class loader. void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) { FOR_ALL_DICTIONARY(cld) { cld->dictionary()->classes_do(f); } } // Only walks the classes defined in this class loader. void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) { FOR_ALL_DICTIONARY(cld) { cld->dictionary()->classes_do(f, CHECK); } } // Walks all entries in the dictionary including entries initiated by this class loader. void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) { FOR_ALL_DICTIONARY(cld) { cld->dictionary()->all_entries_do(f); } } void ClassLoaderDataGraph::verify_dictionary() { FOR_ALL_DICTIONARY(cld) { cld->dictionary()->verify(); } } void ClassLoaderDataGraph::print_dictionary(bool details) { FOR_ALL_DICTIONARY(cld) { tty->print("Dictionary for class loader "); cld->print_value(); tty->cr(); cld->dictionary()->print(details); } } GrowableArray* ClassLoaderDataGraph::new_clds() { assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); GrowableArray* array = new GrowableArray(); // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); ClassLoaderData* curr = _head; while (curr != _saved_head) { if (!curr->claimed()) { array->push(curr); if (log_is_enabled(Debug, class, loader, data)) { outputStream* log = Log(class, loader, data)::debug_stream(); log->print("found new CLD: "); curr->print_value_on(log); log->cr(); } } curr = curr->_next; } return array; } bool ClassLoaderDataGraph::unload_list_contains(const void* x) { assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { return true; } } return false; } #ifndef PRODUCT bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { if (loader_data == data) { return true; } } return false; } #endif // PRODUCT // Move class loader data from main list to the unloaded list for unloading // and deallocation later. bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_previous_versions) { ClassLoaderData* data = _head; ClassLoaderData* prev = NULL; bool seen_dead_loader = false; // Mark metadata seen on the stack only so we can delete unneeded entries. // Only walk all metadata, including the expensive code cache walk, for Full GC // and only if class redefinition and if there's previous versions of // Klasses to delete. bool walk_all_metadata = clean_previous_versions && JvmtiExport::has_redefined_a_class() && InstanceKlass::has_previous_versions_and_reset(); MetadataOnStackMark md_on_stack(walk_all_metadata); // Save previous _unloading pointer for CMS which may add to unloading list before // purging and we don't want to rewalk the previously unloaded class loader data. _saved_unloading = _unloading; data = _head; while (data != NULL) { if (data->is_alive(is_alive_closure)) { // clean metaspace if (walk_all_metadata) { data->classes_do(InstanceKlass::purge_previous_versions); } data->free_deallocate_list(); prev = data; data = data->next(); continue; } seen_dead_loader = true; ClassLoaderData* dead = data; dead->unload(); data = data->next(); // Remove from loader list. // This class loader data will no longer be found // in the ClassLoaderDataGraph. if (prev != NULL) { prev->set_next(data); } else { assert(dead == _head, "sanity check"); _head = data; } dead->set_next(_unloading); _unloading = dead; } if (seen_dead_loader) { data = _head; while (data != NULL) { // Remove entries in the dictionary of live class loader that have // initiated loading classes in a dead class loader. if (data->dictionary() != NULL) { data->dictionary()->do_unloading(); } // Walk a ModuleEntry's reads, and a PackageEntry's exports // lists to determine if there are modules on those lists that are now // dead and should be removed. A module's life cycle is equivalent // to its defining class loader's life cycle. Since a module is // considered dead if its class loader is dead, these walks must // occur after each class loader's aliveness is determined. if (data->packages() != NULL) { data->packages()->purge_all_package_exports(); } if (data->modules_defined()) { data->modules()->purge_all_module_reads(); } data = data->next(); } post_class_unload_events(); } return seen_dead_loader; } void ClassLoaderDataGraph::purge() { assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); ClassLoaderData* list = _unloading; _unloading = NULL; ClassLoaderData* next = list; bool classes_unloaded = false; while (next != NULL) { ClassLoaderData* purge_me = next; next = purge_me->next(); delete purge_me; classes_unloaded = true; } if (classes_unloaded) { Metaspace::purge(); set_metaspace_oom(false); } } void ClassLoaderDataGraph::post_class_unload_events() { #if INCLUDE_TRACE assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); if (Tracing::enabled()) { if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { assert(_unloading != NULL, "need class loader data unload list!"); _class_unload_time = Ticks::now(); classes_unloading_do(&class_unload_event); } Tracing::on_unloading_classes(); } #endif } // CDS support // Global metaspaces for writing information to the shared archive. When // application CDS is supported, we may need one per metaspace, so this // sort of looks like it. Metaspace* ClassLoaderData::_ro_metaspace = NULL; Metaspace* ClassLoaderData::_rw_metaspace = NULL; static bool _shared_metaspaces_initialized = false; // Initialize shared metaspaces (change to call from somewhere not lazily) void ClassLoaderData::initialize_shared_metaspaces() { assert(DumpSharedSpaces, "only use this for dumping shared spaces"); assert(this == ClassLoaderData::the_null_class_loader_data(), "only supported for null loader data for now"); assert (!_shared_metaspaces_initialized, "only initialize once"); MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); _shared_metaspaces_initialized = true; } Metaspace* ClassLoaderData::ro_metaspace() { assert(_ro_metaspace != NULL, "should already be initialized"); return _ro_metaspace; } Metaspace* ClassLoaderData::rw_metaspace() { assert(_rw_metaspace != NULL, "should already be initialized"); return _rw_metaspace; } ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() : _next_klass(NULL) { ClassLoaderData* cld = ClassLoaderDataGraph::_head; Klass* klass = NULL; // Find the first klass in the CLDG. while (cld != NULL) { assert_locked_or_safepoint(cld->metaspace_lock()); klass = cld->_klasses; if (klass != NULL) { _next_klass = klass; return; } cld = cld->next(); } } Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { Klass* next = klass->next_link(); if (next != NULL) { return next; } // No more klasses in the current CLD. Time to find a new CLD. ClassLoaderData* cld = klass->class_loader_data(); assert_locked_or_safepoint(cld->metaspace_lock()); while (next == NULL) { cld = cld->next(); if (cld == NULL) { break; } next = cld->_klasses; } return next; } Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { Klass* head = _next_klass; while (head != NULL) { Klass* next = next_klass_in_cldg(head); Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); if (old_head == head) { return head; // Won the CAS. } head = old_head; } // Nothing more for the iterator to hand out. assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); return NULL; } ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { _data = ClassLoaderDataGraph::_head; } ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} #ifndef PRODUCT // callable from debugger extern "C" int print_loader_data_graph() { ClassLoaderDataGraph::dump_on(tty); return 0; } void ClassLoaderDataGraph::verify() { for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { data->verify(); } } void ClassLoaderDataGraph::dump_on(outputStream * const out) { for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { data->dump(out); } MetaspaceAux::dump(out); } #endif // PRODUCT void ClassLoaderData::print_value_on(outputStream* out) const { if (class_loader() == NULL) { out->print("NULL class_loader"); } else { out->print("class loader " INTPTR_FORMAT " ", p2i(this)); class_loader()->print_value_on(out); } } void ClassLoaderData::print_on(outputStream* out) const { if (class_loader() == NULL) { out->print("NULL class_loader"); } else { out->print("class loader " INTPTR_FORMAT " ", p2i(this)); class_loader()->print_on(out); } } #if INCLUDE_TRACE Ticks ClassLoaderDataGraph::_class_unload_time; void ClassLoaderDataGraph::class_unload_event(Klass* const k) { assert(k != NULL, "invariant"); // post class unload event EventClassUnload event(UNTIMED); event.set_endtime(_class_unload_time); event.set_unloadedClass(k); event.set_definingClassLoader(k->class_loader_data()); event.commit(); } #endif // INCLUDE_TRACE