--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/classfile/classLoaderData.hpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,419 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP
+#define SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP
+
+#include "memory/allocation.hpp"
+#include "memory/memRegion.hpp"
+#include "memory/metaspace.hpp"
+#include "memory/metaspaceCounters.hpp"
+#include "oops/oopHandle.hpp"
+#include "runtime/mutex.hpp"
+#include "trace/traceMacros.hpp"
+#include "utilities/growableArray.hpp"
+#include "utilities/macros.hpp"
+#if INCLUDE_TRACE
+#include "utilities/ticks.hpp"
+#endif
+
+//
+// A class loader represents a linkset. Conceptually, a linkset identifies
+// the complete transitive closure of resolved links that a dynamic linker can
+// produce.
+//
+// A ClassLoaderData also encapsulates the allocation space, called a metaspace,
+// used by the dynamic linker to allocate the runtime representation of all
+// the types it defines.
+//
+// ClassLoaderData are stored in the runtime representation of classes,
+// and provides iterators for root tracing and other GC operations.
+
+class ClassLoaderData;
+class JNIMethodBlock;
+class Metadebug;
+class ModuleEntry;
+class PackageEntry;
+class ModuleEntryTable;
+class PackageEntryTable;
+class DictionaryEntry;
+class Dictionary;
+
+// GC root for walking class loader data created
+
+class ClassLoaderDataGraph : public AllStatic {
+ friend class ClassLoaderData;
+ friend class ClassLoaderDataGraphMetaspaceIterator;
+ friend class ClassLoaderDataGraphKlassIteratorAtomic;
+ friend class ClassLoaderDataGraphKlassIteratorStatic;
+ friend class VMStructs;
+ private:
+ // All CLDs (except the null CLD) can be reached by walking _head->_next->...
+ static ClassLoaderData* _head;
+ static ClassLoaderData* _unloading;
+ // CMS support.
+ static ClassLoaderData* _saved_head;
+ static ClassLoaderData* _saved_unloading;
+ static bool _should_purge;
+ // OOM has been seen in metaspace allocation. Used to prevent some
+ // allocations until class unloading
+ static bool _metaspace_oom;
+
+ static ClassLoaderData* add(Handle class_loader, bool anonymous, TRAPS);
+ static void post_class_unload_events();
+ public:
+ static ClassLoaderData* find_or_create(Handle class_loader, TRAPS);
+ static void purge();
+ static void clear_claimed_marks();
+ // oops do
+ static void oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim);
+ static void keep_alive_oops_do(OopClosure* blk, KlassClosure* klass_closure, bool must_claim);
+ static void always_strong_oops_do(OopClosure* blk, KlassClosure* klass_closure, bool must_claim);
+ // cld do
+ static void cld_do(CLDClosure* cl);
+ static void cld_unloading_do(CLDClosure* cl);
+ static void roots_cld_do(CLDClosure* strong, CLDClosure* weak);
+ static void keep_alive_cld_do(CLDClosure* cl);
+ static void always_strong_cld_do(CLDClosure* cl);
+ // klass do
+ // Walking classes through the ClassLoaderDataGraph include array classes. It also includes
+ // classes that are allocated but not loaded, classes that have errors, and scratch classes
+ // for redefinition. These classes are removed during the next class unloading.
+ // Walking the ClassLoaderDataGraph also includes anonymous classes.
+ static void classes_do(KlassClosure* klass_closure);
+ static void classes_do(void f(Klass* const));
+ static void methods_do(void f(Method*));
+ static void modules_do(void f(ModuleEntry*));
+ static void modules_unloading_do(void f(ModuleEntry*));
+ static void packages_do(void f(PackageEntry*));
+ static void packages_unloading_do(void f(PackageEntry*));
+ static void loaded_classes_do(KlassClosure* klass_closure);
+ static void classes_unloading_do(void f(Klass* const));
+ static bool do_unloading(BoolObjectClosure* is_alive, bool clean_previous_versions);
+
+ // dictionary do
+ // Iterate over all klasses in dictionary, but
+ // just the classes from defining class loaders.
+ static void dictionary_classes_do(void f(InstanceKlass*));
+ // Added for initialize_itable_for_klass to handle exceptions.
+ static void dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS);
+
+ // Iterate all classes and their class loaders, including initiating class loaders.
+ static void dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*));
+
+ // VM_CounterDecay iteration support
+ static InstanceKlass* try_get_next_class();
+
+ static void verify_dictionary();
+ static void print_dictionary(outputStream* st);
+ static void print_dictionary_statistics(outputStream* st);
+
+ // CMS support.
+ static void remember_new_clds(bool remember) { _saved_head = (remember ? _head : NULL); }
+ static GrowableArray<ClassLoaderData*>* new_clds();
+
+ static void set_should_purge(bool b) { _should_purge = b; }
+ static void purge_if_needed() {
+ // Only purge the CLDG for CMS if concurrent sweep is complete.
+ if (_should_purge) {
+ purge();
+ // reset for next time.
+ set_should_purge(false);
+ }
+ }
+
+ static bool has_metaspace_oom() { return _metaspace_oom; }
+ static void set_metaspace_oom(bool value) { _metaspace_oom = value; }
+
+ static void dump_on(outputStream * const out) PRODUCT_RETURN;
+ static void dump() { dump_on(tty); }
+ static void verify();
+ static void print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS);
+
+ static bool unload_list_contains(const void* x);
+#ifndef PRODUCT
+ static bool contains_loader_data(ClassLoaderData* loader_data);
+#endif
+
+#if INCLUDE_TRACE
+ private:
+ static Ticks _class_unload_time;
+ static void class_unload_event(Klass* const k);
+#endif
+};
+
+// ClassLoaderData class
+
+class ClassLoaderData : public CHeapObj<mtClass> {
+ friend class VMStructs;
+ private:
+ class Dependencies VALUE_OBJ_CLASS_SPEC {
+ objArrayOop _list_head;
+ void locked_add(objArrayHandle last,
+ objArrayHandle new_dependency,
+ Thread* THREAD);
+ public:
+ Dependencies() : _list_head(NULL) {}
+ Dependencies(TRAPS) : _list_head(NULL) {
+ init(CHECK);
+ }
+ void add(Handle dependency, TRAPS);
+ void init(TRAPS);
+ void oops_do(OopClosure* f);
+ };
+
+ class ChunkedHandleList VALUE_OBJ_CLASS_SPEC {
+ struct Chunk : public CHeapObj<mtClass> {
+ static const size_t CAPACITY = 32;
+
+ oop _data[CAPACITY];
+ volatile juint _size;
+ Chunk* _next;
+
+ Chunk(Chunk* c) : _next(c), _size(0) { }
+ };
+
+ Chunk* _head;
+
+ void oops_do_chunk(OopClosure* f, Chunk* c, const juint size);
+
+ public:
+ ChunkedHandleList() : _head(NULL) {}
+ ~ChunkedHandleList();
+
+ // Only one thread at a time can add, guarded by ClassLoaderData::metaspace_lock().
+ // However, multiple threads can execute oops_do concurrently with add.
+ oop* add(oop o);
+#ifdef ASSERT
+ bool contains(oop* p);
+#endif
+ void oops_do(OopClosure* f);
+ };
+
+ friend class ClassLoaderDataGraph;
+ friend class ClassLoaderDataGraphKlassIteratorAtomic;
+ friend class ClassLoaderDataGraphKlassIteratorStatic;
+ friend class ClassLoaderDataGraphMetaspaceIterator;
+ friend class MetaDataFactory;
+ friend class Method;
+
+ static ClassLoaderData * _the_null_class_loader_data;
+
+ oop _class_loader; // oop used to uniquely identify a class loader
+ // class loader or a canonical class path
+ Dependencies _dependencies; // holds dependencies from this class loader
+ // data to others.
+
+ Metaspace * volatile _metaspace; // Meta-space where meta-data defined by the
+ // classes in the class loader are allocated.
+ Mutex* _metaspace_lock; // Locks the metaspace for allocations and setup.
+ bool _unloading; // true if this class loader goes away
+ bool _is_anonymous; // if this CLD is for an anonymous class
+ s2 _keep_alive; // if this CLD is kept alive without a keep_alive_object().
+ // Used for anonymous classes and the boot class
+ // loader. _keep_alive does not need to be volatile or
+ // atomic since there is one unique CLD per anonymous class.
+ volatile int _claimed; // true if claimed, for example during GC traces.
+ // To avoid applying oop closure more than once.
+ // Has to be an int because we cas it.
+ ChunkedHandleList _handles; // Handles to constant pool arrays, Modules, etc, which
+ // have the same life cycle of the corresponding ClassLoader.
+
+ Klass* volatile _klasses; // The classes defined by the class loader.
+ PackageEntryTable* volatile _packages; // The packages defined by the class loader.
+ ModuleEntryTable* volatile _modules; // The modules defined by the class loader.
+ ModuleEntry* _unnamed_module; // This class loader's unnamed module.
+ Dictionary* _dictionary; // The loaded InstanceKlasses, including initiated by this class loader
+
+ // These method IDs are created for the class loader and set to NULL when the
+ // class loader is unloaded. They are rarely freed, only for redefine classes
+ // and if they lose a data race in InstanceKlass.
+ JNIMethodBlock* _jmethod_ids;
+
+ // Metadata to be deallocated when it's safe at class unloading, when
+ // this class loader isn't unloaded itself.
+ GrowableArray<Metadata*>* _deallocate_list;
+
+ // Support for walking class loader data objects
+ ClassLoaderData* _next; /// Next loader_datas created
+
+ // ReadOnly and ReadWrite metaspaces (static because only on the null
+ // class loader for now).
+ static Metaspace* _ro_metaspace;
+ static Metaspace* _rw_metaspace;
+
+ TRACE_DEFINE_TRACE_ID_FIELD;
+
+ void set_next(ClassLoaderData* next) { _next = next; }
+ ClassLoaderData* next() const { return _next; }
+
+ ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies);
+ ~ClassLoaderData();
+
+ // GC interface.
+ void clear_claimed() { _claimed = 0; }
+ bool claimed() const { return _claimed == 1; }
+ bool claim();
+
+ void unload();
+ bool keep_alive() const { return _keep_alive > 0; }
+ void classes_do(void f(Klass*));
+ void loaded_classes_do(KlassClosure* klass_closure);
+ void classes_do(void f(InstanceKlass*));
+ void methods_do(void f(Method*));
+ void modules_do(void f(ModuleEntry*));
+ void packages_do(void f(PackageEntry*));
+
+ // Deallocate free list during class unloading.
+ void free_deallocate_list();
+
+ // Allocate out of this class loader data
+ MetaWord* allocate(size_t size);
+
+ Dictionary* create_dictionary();
+ public:
+
+ bool is_alive(BoolObjectClosure* is_alive_closure) const;
+
+ // Accessors
+ Metaspace* metaspace_or_null() const { return _metaspace; }
+
+ static ClassLoaderData* the_null_class_loader_data() {
+ return _the_null_class_loader_data;
+ }
+
+ Mutex* metaspace_lock() const { return _metaspace_lock; }
+
+ bool is_anonymous() const { return _is_anonymous; }
+
+ static void init_null_class_loader_data() {
+ assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
+ assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
+
+ // We explicitly initialize the Dependencies object at a later phase in the initialization
+ _the_null_class_loader_data = new ClassLoaderData(Handle(), false, Dependencies());
+ ClassLoaderDataGraph::_head = _the_null_class_loader_data;
+ assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
+ }
+
+ bool is_the_null_class_loader_data() const {
+ return this == _the_null_class_loader_data;
+ }
+ bool is_system_class_loader_data() const;
+ bool is_platform_class_loader_data() const;
+ bool is_builtin_class_loader_data() const;
+
+ // The Metaspace is created lazily so may be NULL. This
+ // method will allocate a Metaspace if needed.
+ Metaspace* metaspace_non_null();
+
+ oop class_loader() const { return _class_loader; }
+
+ // The object the GC is using to keep this ClassLoaderData alive.
+ oop keep_alive_object() const;
+
+ // Returns true if this class loader data is for a loader going away.
+ bool is_unloading() const {
+ assert(!(is_the_null_class_loader_data() && _unloading), "The null class loader can never be unloaded");
+ return _unloading;
+ }
+
+ // Used to refcount an anonymous class's CLD in order to
+ // indicate their aliveness without a keep_alive_object().
+ void inc_keep_alive();
+ void dec_keep_alive();
+
+ inline unsigned int identity_hash() const { return (unsigned int)(((intptr_t)this) >> 3); }
+
+ // Used when tracing from klasses.
+ void oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim);
+
+ void classes_do(KlassClosure* klass_closure);
+ Klass* klasses() { return _klasses; }
+
+ JNIMethodBlock* jmethod_ids() const { return _jmethod_ids; }
+ void set_jmethod_ids(JNIMethodBlock* new_block) { _jmethod_ids = new_block; }
+
+ void print() { print_on(tty); }
+ void print_on(outputStream* out) const;
+ void print_value() { print_value_on(tty); }
+ void print_value_on(outputStream* out) const;
+ void dump(outputStream * const out) PRODUCT_RETURN;
+ void verify();
+ const char* loader_name();
+
+ OopHandle add_handle(Handle h);
+ void remove_handle(OopHandle h);
+ void init_handle_locked(OopHandle& pd, Handle h); // used for concurrent access to ModuleEntry::_pd field
+ void add_class(Klass* k, bool publicize = true);
+ void remove_class(Klass* k);
+ bool contains_klass(Klass* k);
+ void record_dependency(const Klass* to, TRAPS);
+ void init_dependencies(TRAPS);
+ PackageEntryTable* packages() { return _packages; }
+ ModuleEntry* unnamed_module() { return _unnamed_module; }
+ ModuleEntryTable* modules();
+ bool modules_defined() { return (_modules != NULL); }
+
+ // Loaded class dictionary
+ Dictionary* dictionary() const { return _dictionary; }
+
+ void add_to_deallocate_list(Metadata* m);
+
+ static ClassLoaderData* class_loader_data(oop loader);
+ static ClassLoaderData* class_loader_data_or_null(oop loader);
+ static ClassLoaderData* anonymous_class_loader_data(oop loader, TRAPS);
+ static void print_loader(ClassLoaderData *loader_data, outputStream *out);
+
+ TRACE_DEFINE_TRACE_ID_METHODS;
+};
+
+// An iterator that distributes Klasses to parallel worker threads.
+class ClassLoaderDataGraphKlassIteratorAtomic : public StackObj {
+ Klass* volatile _next_klass;
+ public:
+ ClassLoaderDataGraphKlassIteratorAtomic();
+ Klass* next_klass();
+ private:
+ static Klass* next_klass_in_cldg(Klass* klass);
+};
+
+class ClassLoaderDataGraphMetaspaceIterator : public StackObj {
+ ClassLoaderData* _data;
+ public:
+ ClassLoaderDataGraphMetaspaceIterator();
+ ~ClassLoaderDataGraphMetaspaceIterator();
+ bool repeat() { return _data != NULL; }
+ Metaspace* get_next() {
+ assert(_data != NULL, "Should not be NULL in call to the iterator");
+ Metaspace* result = _data->metaspace_or_null();
+ _data = _data->next();
+ // This result might be NULL for class loaders without metaspace
+ // yet. It would be nice to return only non-null results but
+ // there is no guarantee that there will be a non-null result
+ // down the list so the caller is going to have to check.
+ return result;
+ }
+};
+#endif // SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP