jdk8-mips64-public/hotspot: src/share/vm/classfile/classLoaderData.hpp@2c6ef90f030a (annotated)

src/share/vm/classfile/classLoaderData.hpp@2c6ef90f030a (annotated)

src/share/vm/classfile/classLoaderData.hpp

Mon, 07 Jul 2014 10:12:40 +0200

author: stefank
date: Mon, 07 Jul 2014 10:12:40 +0200
changeset 6992: 2c6ef90f030a
parent 6974: 556a06aec3fa
child 7333: b12a2a9b05ca
permissions: -rw-r--r--

8049421: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
Contributed-by: stefan.karlsson@oracle.com, mikael.gerdin@oracle.com

 /*
  * Copyright (c) 2012, 2014, 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 "runtime/mutex.hpp"
 #include "utilities/growableArray.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 the
 // system dictionary, are roots of garbage collection, and provides iterators
 // for root tracing and other GC operations.
 class ClassLoaderData;
 class JNIMethodBlock;
 class JNIHandleBlock;
 class Metadebug;
 // GC root for walking class loader data created
 class ClassLoaderDataGraph : public AllStatic {
   friend class ClassLoaderData;
   friend class ClassLoaderDataGraphMetaspaceIterator;
   friend class ClassLoaderDataGraphKlassIteratorAtomic;
   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;
   static ClassLoaderData* add(Handle class_loader, bool anonymous, TRAPS);
   static void post_class_unload_events(void);
  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 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
   static void classes_do(KlassClosure* klass_closure);
   static void classes_do(void f(Klass* const));
   static void loaded_classes_do(KlassClosure* klass_closure);
   static void classes_unloading_do(void f(Klass* const));
   static bool do_unloading(BoolObjectClosure* is_alive);
   // 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 void dump_on(outputStream * const out) PRODUCT_RETURN;
   static void dump() { dump_on(tty); }
   static void verify();
   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);
   };
   friend class ClassLoaderDataGraph;
   friend class ClassLoaderDataGraphKlassIteratorAtomic;
   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 * _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 _keep_alive;        // if this CLD is kept alive without a keep_alive_object().
   bool _is_anonymous;      // if this CLD is for an 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.
   Klass* _klasses;         // The classes defined by the class loader.
   JNIHandleBlock* _handles; // Handles to constant pool arrays
   // 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;
   void set_next(ClassLoaderData* next) { _next = next; }
   ClassLoaderData* next() const        { return _next; }
   ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies);
   ~ClassLoaderData();
   void set_metaspace(Metaspace* m) { _metaspace = m; }
   JNIHandleBlock* handles() const;
   void set_handles(JNIHandleBlock* handles);
   Mutex* metaspace_lock() const { return _metaspace_lock; }
   // GC interface.
   void clear_claimed()          { _claimed = 0; }
   bool claimed() const          { return _claimed == 1; }
   bool claim();
   void unload();
   bool keep_alive() const       { return _keep_alive; }
   void classes_do(void f(Klass*));
   void loaded_classes_do(KlassClosure* klass_closure);
   void classes_do(void f(InstanceKlass*));
   // Deallocate free list during class unloading.
   void free_deallocate_list();
   // Allocate out of this class loader data
   MetaWord* allocate(size_t size);
  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;
   }
   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((oop)NULL, false, Dependencies());
     ClassLoaderDataGraph::_head = _the_null_class_loader_data;
     assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
     if (DumpSharedSpaces) {
       _the_null_class_loader_data->initialize_shared_metaspaces();
     }
   }
   bool is_the_null_class_loader_data() const {
     return this == _the_null_class_loader_data;
   }
   bool is_ext_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 make sure that this CLD is not unloaded.
   void set_keep_alive(bool value) { _keep_alive = value; }
   unsigned int identity_hash() {
     return _class_loader == NULL ? 0 : _class_loader->identity_hash();
   }
   // Used when tracing from klasses.
   void oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim);
   void classes_do(KlassClosure* klass_closure);
   JNIMethodBlock* jmethod_ids() const              { return _jmethod_ids; }
   void set_jmethod_ids(JNIMethodBlock* new_block)  { _jmethod_ids = new_block; }
   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();
   jobject add_handle(Handle h);
   void add_class(Klass* k);
   void remove_class(Klass* k);
   bool contains_klass(Klass* k);
   void record_dependency(Klass* to, TRAPS);
   void init_dependencies(TRAPS);
   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);
   // CDS support
   Metaspace* ro_metaspace();
   Metaspace* rw_metaspace();
   void initialize_shared_metaspaces();
 };
 // An iterator that distributes Klasses to parallel worker threads.
 class ClassLoaderDataGraphKlassIteratorAtomic : public StackObj {
   volatile Klass* _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

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/classfile/classLoaderData.hpp@2c6ef90f030a (annotated)

src/share/vm/classfile/classLoaderData.hpp