coleenp@4037: /*
coleenp@6316:  * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
coleenp@4037:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
coleenp@4037:  *
coleenp@4037:  * This code is free software; you can redistribute it and/or modify it
coleenp@4037:  * under the terms of the GNU General Public License version 2 only, as
coleenp@4037:  * published by the Free Software Foundation.
coleenp@4037:  *
coleenp@4037:  * This code is distributed in the hope that it will be useful, but WITHOUT
coleenp@4037:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
katleman@4376:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
coleenp@4037:  * version 2 for more details (a copy is included in the LICENSE file that
coleenp@4037:  * accompanied this code).
coleenp@4037:  *
coleenp@4037:  * You should have received a copy of the GNU General Public License version
coleenp@4037:  * 2 along with this work; if not, write to the Free Software Foundation,
coleenp@4037:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
coleenp@4037:  *
coleenp@4037:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
coleenp@4037:  * or visit www.oracle.com if you need additional information or have any
coleenp@4037:  * questions.
coleenp@4037:  *
coleenp@4037:  */
coleenp@4037: 
coleenp@4037: #ifndef SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP
coleenp@4037: #define SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP
coleenp@4037: 
coleenp@4037: #include "memory/allocation.hpp"
coleenp@4037: #include "memory/memRegion.hpp"
coleenp@4037: #include "memory/metaspace.hpp"
coleenp@4037: #include "memory/metaspaceCounters.hpp"
coleenp@4037: #include "runtime/mutex.hpp"
coleenp@4037: #include "utilities/growableArray.hpp"
sla@5237: #if INCLUDE_TRACE
mgronlun@6131: # include "utilities/ticks.hpp"
sla@5237: #endif
sla@5237: 
coleenp@4037: //
coleenp@4037: // A class loader represents a linkset. Conceptually, a linkset identifies
coleenp@4037: // the complete transitive closure of resolved links that a dynamic linker can
coleenp@4037: // produce.
coleenp@4037: //
coleenp@4037: // A ClassLoaderData also encapsulates the allocation space, called a metaspace,
coleenp@4037: // used by the dynamic linker to allocate the runtime representation of all
coleenp@4037: // the types it defines.
coleenp@4037: //
coleenp@4037: // ClassLoaderData are stored in the runtime representation of classes and the
coleenp@4037: // system dictionary, are roots of garbage collection, and provides iterators
coleenp@4037: // for root tracing and other GC operations.
coleenp@4037: 
coleenp@4037: class ClassLoaderData;
coleenp@4037: class JNIMethodBlock;
coleenp@4037: class JNIHandleBlock;
coleenp@4037: class Metadebug;
sla@5237: 
coleenp@4037: // GC root for walking class loader data created
coleenp@4037: 
coleenp@4037: class ClassLoaderDataGraph : public AllStatic {
coleenp@4037:   friend class ClassLoaderData;
coleenp@4037:   friend class ClassLoaderDataGraphMetaspaceIterator;
stefank@6992:   friend class ClassLoaderDataGraphKlassIteratorAtomic;
coleenp@4037:   friend class VMStructs;
coleenp@4037:  private:
coleenp@4037:   // All CLDs (except the null CLD) can be reached by walking _head->_next->...
coleenp@4037:   static ClassLoaderData* _head;
coleenp@4037:   static ClassLoaderData* _unloading;
coleenp@4037:   // CMS support.
coleenp@4037:   static ClassLoaderData* _saved_head;
mgronlun@6742:   static ClassLoaderData* _saved_unloading;
coleenp@6678:   static bool _should_purge;
coleenp@4037: 
mgerdin@5013:   static ClassLoaderData* add(Handle class_loader, bool anonymous, TRAPS);
sla@5237:   static void post_class_unload_events(void);
coleenp@4037:  public:
coleenp@4304:   static ClassLoaderData* find_or_create(Handle class_loader, TRAPS);
coleenp@4037:   static void purge();
coleenp@4037:   static void clear_claimed_marks();
stefank@6992:   // oops do
coleenp@4037:   static void oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim);
stefank@6992:   static void keep_alive_oops_do(OopClosure* blk, KlassClosure* klass_closure, bool must_claim);
coleenp@4037:   static void always_strong_oops_do(OopClosure* blk, KlassClosure* klass_closure, bool must_claim);
stefank@6992:   // cld do
stefank@6992:   static void cld_do(CLDClosure* cl);
stefank@6992:   static void roots_cld_do(CLDClosure* strong, CLDClosure* weak);
stefank@6992:   static void keep_alive_cld_do(CLDClosure* cl);
stefank@6992:   static void always_strong_cld_do(CLDClosure* cl);
stefank@6992:   // klass do
coleenp@4037:   static void classes_do(KlassClosure* klass_closure);
sla@5237:   static void classes_do(void f(Klass* const));
farvidsson@6024:   static void loaded_classes_do(KlassClosure* klass_closure);
sla@5237:   static void classes_unloading_do(void f(Klass* const));
coleenp@4037:   static bool do_unloading(BoolObjectClosure* is_alive);
coleenp@4037: 
coleenp@4037:   // CMS support.
coleenp@4037:   static void remember_new_clds(bool remember) { _saved_head = (remember ? _head : NULL); }
coleenp@4037:   static GrowableArray<ClassLoaderData*>* new_clds();
coleenp@4037: 
coleenp@6678:   static void set_should_purge(bool b) { _should_purge = b; }
coleenp@6678:   static void purge_if_needed() {
coleenp@6678:     // Only purge the CLDG for CMS if concurrent sweep is complete.
coleenp@6678:     if (_should_purge) {
coleenp@6678:       purge();
coleenp@6678:       // reset for next time.
coleenp@6678:       set_should_purge(false);
coleenp@6678:     }
coleenp@6678:   }
coleenp@6678: 
coleenp@4037:   static void dump_on(outputStream * const out) PRODUCT_RETURN;
coleenp@4037:   static void dump() { dump_on(tty); }
coleenp@4037:   static void verify();
coleenp@4037: 
stefank@6992:   static bool unload_list_contains(const void* x);
coleenp@4037: #ifndef PRODUCT
coleenp@4037:   static bool contains_loader_data(ClassLoaderData* loader_data);
coleenp@4037: #endif
sla@5237: 
sla@5237: #if INCLUDE_TRACE
sla@5237:  private:
mgronlun@6131:   static Ticks _class_unload_time;
sla@5237:   static void class_unload_event(Klass* const k);
sla@5237: #endif
coleenp@4037: };
coleenp@4037: 
coleenp@4037: // ClassLoaderData class
coleenp@4037: 
coleenp@4037: class ClassLoaderData : public CHeapObj<mtClass> {
coleenp@4037:   friend class VMStructs;
coleenp@4037:  private:
mgerdin@4903:   class Dependencies VALUE_OBJ_CLASS_SPEC {
mgerdin@4903:     objArrayOop _list_head;
mgerdin@4903:     void locked_add(objArrayHandle last,
mgerdin@4903:                     objArrayHandle new_dependency,
mgerdin@4903:                     Thread* THREAD);
mgerdin@4903:    public:
mgerdin@4903:     Dependencies() : _list_head(NULL) {}
mgerdin@5016:     Dependencies(TRAPS) : _list_head(NULL) {
mgerdin@5016:       init(CHECK);
mgerdin@5016:     }
mgerdin@4903:     void add(Handle dependency, TRAPS);
mgerdin@4903:     void init(TRAPS);
mgerdin@4903:     void oops_do(OopClosure* f);
mgerdin@4903:   };
mgerdin@4903: 
coleenp@4037:   friend class ClassLoaderDataGraph;
stefank@6992:   friend class ClassLoaderDataGraphKlassIteratorAtomic;
coleenp@4037:   friend class ClassLoaderDataGraphMetaspaceIterator;
coleenp@4037:   friend class MetaDataFactory;
coleenp@4037:   friend class Method;
coleenp@4037: 
coleenp@4037:   static ClassLoaderData * _the_null_class_loader_data;
coleenp@4037: 
mgerdin@4903:   oop _class_loader;          // oop used to uniquely identify a class loader
mgerdin@4903:                               // class loader or a canonical class path
mgerdin@4903:   Dependencies _dependencies; // holds dependencies from this class loader
mgerdin@4903:                               // data to others.
mgerdin@4903: 
coleenp@4037:   Metaspace * _metaspace;  // Meta-space where meta-data defined by the
coleenp@4037:                            // classes in the class loader are allocated.
coleenp@4037:   Mutex* _metaspace_lock;  // Locks the metaspace for allocations and setup.
coleenp@4037:   bool _unloading;         // true if this class loader goes away
stefank@6974:   bool _keep_alive;        // if this CLD is kept alive without a keep_alive_object().
coleenp@4345:   bool _is_anonymous;      // if this CLD is for an anonymous class
coleenp@4037:   volatile int _claimed;   // true if claimed, for example during GC traces.
coleenp@4037:                            // To avoid applying oop closure more than once.
coleenp@4037:                            // Has to be an int because we cas it.
coleenp@4037:   Klass* _klasses;         // The classes defined by the class loader.
coleenp@4037: 
coleenp@4037:   JNIHandleBlock* _handles; // Handles to constant pool arrays
coleenp@4037: 
coleenp@4037:   // These method IDs are created for the class loader and set to NULL when the
coleenp@4037:   // class loader is unloaded.  They are rarely freed, only for redefine classes
coleenp@4037:   // and if they lose a data race in InstanceKlass.
coleenp@4037:   JNIMethodBlock*                  _jmethod_ids;
coleenp@4037: 
coleenp@4037:   // Metadata to be deallocated when it's safe at class unloading, when
coleenp@4037:   // this class loader isn't unloaded itself.
coleenp@4037:   GrowableArray<Metadata*>*      _deallocate_list;
coleenp@4037: 
coleenp@4037:   // Support for walking class loader data objects
coleenp@4037:   ClassLoaderData* _next; /// Next loader_datas created
coleenp@4037: 
coleenp@4037:   // ReadOnly and ReadWrite metaspaces (static because only on the null
coleenp@4037:   // class loader for now).
coleenp@4037:   static Metaspace* _ro_metaspace;
coleenp@4037:   static Metaspace* _rw_metaspace;
coleenp@4037: 
coleenp@4037:   void set_next(ClassLoaderData* next) { _next = next; }
coleenp@4037:   ClassLoaderData* next() const        { return _next; }
coleenp@4037: 
mgerdin@5016:   ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies);
coleenp@4037:   ~ClassLoaderData();
coleenp@4037: 
coleenp@4037:   void set_metaspace(Metaspace* m) { _metaspace = m; }
coleenp@4037: 
coleenp@4037:   JNIHandleBlock* handles() const;
coleenp@4037:   void set_handles(JNIHandleBlock* handles);
coleenp@4037: 
coleenp@4037:   Mutex* metaspace_lock() const { return _metaspace_lock; }
coleenp@4037: 
coleenp@4037:   // GC interface.
coleenp@4037:   void clear_claimed()          { _claimed = 0; }
coleenp@4037:   bool claimed() const          { return _claimed == 1; }
coleenp@4037:   bool claim();
coleenp@4037: 
coleenp@4304:   void unload();
coleenp@4304:   bool keep_alive() const       { return _keep_alive; }
sla@5237:   void classes_do(void f(Klass*));
farvidsson@6024:   void loaded_classes_do(KlassClosure* klass_closure);
coleenp@4037:   void classes_do(void f(InstanceKlass*));
coleenp@4037: 
coleenp@4037:   // Deallocate free list during class unloading.
coleenp@4037:   void free_deallocate_list();
coleenp@4037: 
coleenp@4037:   // Allocate out of this class loader data
coleenp@4037:   MetaWord* allocate(size_t size);
coleenp@4037: 
coleenp@4037:  public:
stefank@6992: 
stefank@6992:   bool is_alive(BoolObjectClosure* is_alive_closure) const;
stefank@6992: 
coleenp@4037:   // Accessors
coleenp@4037:   Metaspace* metaspace_or_null() const     { return _metaspace; }
coleenp@4037: 
coleenp@4037:   static ClassLoaderData* the_null_class_loader_data() {
coleenp@4037:     return _the_null_class_loader_data;
coleenp@4037:   }
coleenp@4037: 
coleenp@4345:   bool is_anonymous() const { return _is_anonymous; }
coleenp@4304: 
coleenp@4037:   static void init_null_class_loader_data() {
coleenp@4037:     assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
coleenp@4037:     assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
mgerdin@5016: 
mgerdin@5016:     // We explicitly initialize the Dependencies object at a later phase in the initialization
mgerdin@5016:     _the_null_class_loader_data = new ClassLoaderData((oop)NULL, false, Dependencies());
coleenp@4037:     ClassLoaderDataGraph::_head = _the_null_class_loader_data;
coleenp@4037:     assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
coleenp@4037:     if (DumpSharedSpaces) {
coleenp@4037:       _the_null_class_loader_data->initialize_shared_metaspaces();
coleenp@4037:     }
coleenp@4037:   }
coleenp@4037: 
coleenp@4037:   bool is_the_null_class_loader_data() const {
coleenp@4037:     return this == _the_null_class_loader_data;
coleenp@4037:   }
twisti@4866:   bool is_ext_class_loader_data() const;
coleenp@4037: 
coleenp@4037:   // The Metaspace is created lazily so may be NULL.  This
coleenp@4037:   // method will allocate a Metaspace if needed.
coleenp@4037:   Metaspace* metaspace_non_null();
coleenp@4037: 
coleenp@4037:   oop class_loader() const      { return _class_loader; }
coleenp@4037: 
stefank@6974:   // The object the GC is using to keep this ClassLoaderData alive.
stefank@6974:   oop keep_alive_object() const;
stefank@6974: 
coleenp@4037:   // Returns true if this class loader data is for a loader going away.
coleenp@4037:   bool is_unloading() const     {
coleenp@4037:     assert(!(is_the_null_class_loader_data() && _unloading), "The null class loader can never be unloaded");
coleenp@4037:     return _unloading;
coleenp@4037:   }
stefank@6974: 
stefank@6974:   // Used to make sure that this CLD is not unloaded.
coleenp@4304:   void set_keep_alive(bool value) { _keep_alive = value; }
coleenp@4037: 
coleenp@4037:   unsigned int identity_hash() {
coleenp@4037:     return _class_loader == NULL ? 0 : _class_loader->identity_hash();
coleenp@4037:   }
coleenp@4037: 
coleenp@4037:   // Used when tracing from klasses.
coleenp@4037:   void oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim);
coleenp@4037: 
coleenp@4037:   void classes_do(KlassClosure* klass_closure);
coleenp@4037: 
coleenp@4037:   JNIMethodBlock* jmethod_ids() const              { return _jmethod_ids; }
coleenp@4037:   void set_jmethod_ids(JNIMethodBlock* new_block)  { _jmethod_ids = new_block; }
coleenp@4037: 
coleenp@4037:   void print_value() { print_value_on(tty); }
acorn@4497:   void print_value_on(outputStream* out) const;
coleenp@4037:   void dump(outputStream * const out) PRODUCT_RETURN;
coleenp@4037:   void verify();
coleenp@4304:   const char* loader_name();
coleenp@4037: 
coleenp@4037:   jobject add_handle(Handle h);
coleenp@4037:   void add_class(Klass* k);
coleenp@4037:   void remove_class(Klass* k);
coleenp@6316:   bool contains_klass(Klass* k);
coleenp@4037:   void record_dependency(Klass* to, TRAPS);
coleenp@4304:   void init_dependencies(TRAPS);
coleenp@4037: 
coleenp@4037:   void add_to_deallocate_list(Metadata* m);
coleenp@4037: 
coleenp@4037:   static ClassLoaderData* class_loader_data(oop loader);
stefank@4667:   static ClassLoaderData* class_loader_data_or_null(oop loader);
coleenp@4304:   static ClassLoaderData* anonymous_class_loader_data(oop loader, TRAPS);
coleenp@4037:   static void print_loader(ClassLoaderData *loader_data, outputStream *out);
coleenp@4037: 
coleenp@4037:   // CDS support
coleenp@4037:   Metaspace* ro_metaspace();
coleenp@4037:   Metaspace* rw_metaspace();
coleenp@4037:   void initialize_shared_metaspaces();
coleenp@4037: };
coleenp@4037: 
stefank@6992: // An iterator that distributes Klasses to parallel worker threads.
stefank@6992: class ClassLoaderDataGraphKlassIteratorAtomic : public StackObj {
stefank@6992:   volatile Klass* _next_klass;
stefank@6992:  public:
stefank@6992:   ClassLoaderDataGraphKlassIteratorAtomic();
stefank@6992:   Klass* next_klass();
stefank@6992:  private:
stefank@6992:   static Klass* next_klass_in_cldg(Klass* klass);
stefank@6992: };
stefank@6992: 
coleenp@4037: class ClassLoaderDataGraphMetaspaceIterator : public StackObj {
coleenp@4037:   ClassLoaderData* _data;
coleenp@4037:  public:
coleenp@4037:   ClassLoaderDataGraphMetaspaceIterator();
coleenp@4037:   ~ClassLoaderDataGraphMetaspaceIterator();
coleenp@4037:   bool repeat() { return _data != NULL; }
coleenp@4037:   Metaspace* get_next() {
coleenp@4037:     assert(_data != NULL, "Should not be NULL in call to the iterator");
coleenp@4037:     Metaspace* result = _data->metaspace_or_null();
coleenp@4037:     _data = _data->next();
coleenp@4037:     // This result might be NULL for class loaders without metaspace
coleenp@4037:     // yet.  It would be nice to return only non-null results but
coleenp@4037:     // there is no guarantee that there will be a non-null result
coleenp@4037:     // down the list so the caller is going to have to check.
coleenp@4037:     return result;
coleenp@4037:   }
coleenp@4037: };
coleenp@4037: #endif // SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP