1 /*

     2  * Copyright (c) 2012, 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) : _class_loader(h_class_loader()),

    68   _metaspace(NULL), _unloading(false), _klasses(NULL),

    69   _claimed(0), _jmethod_ids(NULL), _handles(NULL),

    70   _deallocate_list(NULL), _next(NULL),

    71   _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {

    72     // empty

    73 }

    74 

    75 bool ClassLoaderData::claim() {

    76   if (_claimed == 1) {

    77     return false;

    78   }

    79 

    80   return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;

    81 }

    82 

    83 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {

    84   if (must_claim && !claim()) {

    85     return;

    86   }

    87 

    88   f->do_oop(&_class_loader);

    89   _handles->oops_do(f);

    90   if (klass_closure != NULL) {

    91     classes_do(klass_closure);

    92   }

    93 }

    94 

    95 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {

    96   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {

    97     klass_closure->do_klass(k);

    98   }

    99 }

   100 

   101 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {

   102   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {

   103     if (k->oop_is_instance()) {

   104       f(InstanceKlass::cast(k));

   105     }

   106   }

   107 }

   108 

   109 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {

   110   ClassLoaderData * const from_cld = this;

   111   ClassLoaderData * const to_cld = k->class_loader_data();

   112 

   113   // Records dependency between non-null class loaders only.

   114   if (to_cld->is_the_null_class_loader_data() || from_cld->is_the_null_class_loader_data()) {

   115     return;

   116   }

   117 

   118   // Check that this dependency isn't from the same or parent class_loader

   119   oop to = to_cld->class_loader();

   120   oop from = from_cld->class_loader();

   121 

   122   oop curr = from;

   123   while (curr != NULL) {

   124     if (curr == to) {

   125       return; // this class loader is in the parent list, no need to add it.

   126     }

   127     curr = java_lang_ClassLoader::parent(curr);

   128   }

   129 

   130   // It's a dependency we won't find through GC, add it. This is relatively rare

   131   from_cld->add_dependency(to_cld, CHECK);

   132 }

   133 

   134 bool ClassLoaderData::has_dependency(ClassLoaderData* dependency) {

   135   oop loader = dependency->class_loader();

   136 

   137   // Get objArrayOop out of the class_loader oop and see if this dependency

   138   // is there.  Don't safepoint!  These are all oops.

   139   // Dependency list is (oop class_loader, objArrayOop next)

   140   objArrayOop ok = (objArrayOop)java_lang_ClassLoader::dependencies(class_loader());

   141   while (ok != NULL) {

   142     if (ok->obj_at(0) == loader) {

   143       return true;

   144     }

   145     ok = (objArrayOop)ok->obj_at(1);

   146   }

   147   return false;

   148 }

   149 

   150 void ClassLoaderData::add_dependency(ClassLoaderData* dependency, TRAPS) {

   151   // Minimize the number of duplicates in the list.

   152   if (has_dependency(dependency)) {

   153     return;

   154   }

   155 

   156   // Create a new dependency node with fields for (class_loader, next)

   157   objArrayOop deps = oopFactory::new_objectArray(2, CHECK);

   158   deps->obj_at_put(0, dependency->class_loader());

   159 

   160   // Add this lock free, using compare and exchange, need barriers for GC

   161   // Do the barrier first.

   162   HeapWord* addr = java_lang_ClassLoader::dependencies_addr(class_loader());

   163   while (true) {

   164     oop old_dependency = java_lang_ClassLoader::dependencies(class_loader());

   165     deps->obj_at_put(1, old_dependency);

   166 

   167     oop newold = oopDesc::atomic_compare_exchange_oop((oop)deps, addr, old_dependency, true);

   168     if (newold == old_dependency) {

   169       update_barrier_set((void*)addr, (oop)deps);

   170       // we won the race to add this dependency

   171       break;

   172     }

   173   }

   174 }

   175 

   176 

   177 void ClassLoaderDataGraph::clear_claimed_marks() {

   178   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {

   179     cld->clear_claimed();

   180   }

   181 }

   182 

   183 void ClassLoaderData::add_class(Klass* k) {

   184   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);

   185   Klass* old_value = _klasses;

   186   k->set_next_link(old_value);

   187   // link the new item into the list

   188   _klasses = k;

   189 

   190   if (TraceClassLoaderData && k->class_loader_data() != NULL) {

   191     ResourceMark rm;

   192     tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "

   193                   PTR_FORMAT " loader: " PTR_FORMAT " %s",

   194                   k,

   195                   k->external_name(),

   196                   k->class_loader_data(),

   197                   k->class_loader(),

   198                   k->class_loader() != NULL ? k->class_loader()->klass()->external_name() : "NULL"

   199       );

   200   }

   201 }

   202 

   203 // This is called by InstanceKlass::deallocate_contents() to remove the

   204 // scratch_class for redefine classes.  We need a lock because there it may not

   205 // be called at a safepoint if there's an error.

   206 void ClassLoaderData::remove_class(Klass* scratch_class) {

   207   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);

   208   Klass* prev = NULL;

   209   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {

   210     if (k == scratch_class) {

   211       if (prev == NULL) {

   212         _klasses = k->next_link();

   213       } else {

   214         Klass* next = k->next_link();

   215         prev->set_next_link(next);

   216       }

   217       return;

   218     }

   219     prev = k;

   220   }

   221   ShouldNotReachHere();   // should have found this class!!

   222 }

   223 

   224 ClassLoaderData::~ClassLoaderData() {

   225   Metaspace *m = _metaspace;

   226   if (m != NULL) {

   227     _metaspace = NULL;

   228     // release the metaspace

   229     delete m;

   230     // release the handles

   231     if (_handles != NULL) {

   232       JNIHandleBlock::release_block(_handles);

   233       _handles = NULL;

   234     }

   235   }

   236 

   237   // Clear all the JNI handles for methods

   238   // These aren't deallocated and are going to look like a leak, but that's

   239   // needed because we can't really get rid of jmethodIDs because we don't

   240   // know when native code is going to stop using them.  The spec says that

   241   // they're "invalid" but existing programs likely rely on their being

   242   // NULL after class unloading.

   243   if (_jmethod_ids != NULL) {

   244     Method::clear_jmethod_ids(this);

   245   }

   246   // Delete lock

   247   delete _metaspace_lock;

   248 

   249   // Delete free list

   250   if (_deallocate_list != NULL) {

   251     delete _deallocate_list;

   252   }

   253 }

   254 

   255 Metaspace* ClassLoaderData::metaspace_non_null() {

   256   // If the metaspace has not been allocated, create a new one.  Might want

   257   // to create smaller arena for Reflection class loaders also.

   258   // The reason for the delayed allocation is because some class loaders are

   259   // simply for delegating with no metadata of their own.

   260   if (_metaspace == NULL) {

   261     MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);

   262     // Check again if metaspace has been allocated while we were getting this lock.

   263     if (_metaspace != NULL) {

   264       return _metaspace;

   265     }

   266     if (class_loader() == NULL) {

   267       assert(this == the_null_class_loader_data(), "Must be");

   268       size_t word_size = Metaspace::first_chunk_word_size();

   269       set_metaspace(new Metaspace(_metaspace_lock, word_size));

   270     } else {

   271       set_metaspace(new Metaspace(_metaspace_lock));  // default size for now.

   272     }

   273   }

   274   return _metaspace;

   275 }

   276 

   277 JNIHandleBlock* ClassLoaderData::handles() const           { return _handles; }

   278 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }

   279 

   280 jobject ClassLoaderData::add_handle(Handle h) {

   281   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);

   282   if (handles() == NULL) {

   283     set_handles(JNIHandleBlock::allocate_block());

   284   }

   285   return handles()->allocate_handle(h());

   286 }

   287 

   288 // Add this metadata pointer to be freed when it's safe.  This is only during

   289 // class unloading because Handles might point to this metadata field.

   290 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {

   291   // Metadata in shared region isn't deleted.

   292   if (!m->is_shared()) {

   293     MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);

   294     if (_deallocate_list == NULL) {

   295       _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);

   296     }

   297     _deallocate_list->append_if_missing(m);

   298   }

   299 }

   300 

   301 // Deallocate free metadata on the free list.  How useful the PermGen was!

   302 void ClassLoaderData::free_deallocate_list() {

   303   // Don't need lock, at safepoint

   304   assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");

   305   if (_deallocate_list == NULL) {

   306     return;

   307   }

   308   // Go backwards because this removes entries that are freed.

   309   for (int i = _deallocate_list->length() - 1; i >= 0; i--) {

   310     Metadata* m = _deallocate_list->at(i);

   311     if (!m->on_stack()) {

   312       _deallocate_list->remove_at(i);

   313       // There are only three types of metadata that we deallocate directly.

   314       // Cast them so they can be used by the template function.

   315       if (m->is_method()) {

   316         MetadataFactory::free_metadata(this, (Method*)m);

   317       } else if (m->is_constantPool()) {

   318         MetadataFactory::free_metadata(this, (ConstantPool*)m);

   319       } else if (m->is_klass()) {

   320         MetadataFactory::free_metadata(this, (InstanceKlass*)m);

   321       } else {

   322         ShouldNotReachHere();

   323       }

   324     }

   325   }

   326 }

   327 

   328 #ifndef PRODUCT

   329 void ClassLoaderData::print_loader(ClassLoaderData *loader_data, outputStream* out) {

   330   oop class_loader = loader_data->class_loader();

   331   out->print("%s", SystemDictionary::loader_name(class_loader));

   332 }

   333 

   334 // Define to dump klasses

   335 #undef CLD_DUMP_KLASSES

   336 

   337 void ClassLoaderData::dump(outputStream * const out) {

   338   ResourceMark rm;

   339   out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",

   340       this, class_loader(),

   341       class_loader() != NULL ? class_loader()->klass() : NULL,

   342       class_loader() != NULL ? class_loader()->klass()->external_name() : "NULL");

   343   if (claimed()) out->print(" claimed ");

   344   if (is_unloading()) out->print(" unloading ");

   345   out->print(" handles " INTPTR_FORMAT, handles());

   346   out->cr();

   347   if (metaspace_or_null() != NULL) {

   348     out->print_cr("metaspace: " PTR_FORMAT, metaspace_or_null());

   349     metaspace_or_null()->dump(out);

   350   } else {

   351     out->print_cr("metaspace: NULL");

   352   }

   353 

   354 #ifdef CLD_DUMP_KLASSES

   355   if (Verbose) {

   356     ResourceMark rm;

   357     Klass* k = _klasses;

   358     while (k != NULL) {

   359       out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),

   360           k->has_modified_oops(), k->has_accumulated_modified_oops());

   361       k = k->next_link();

   362     }

   363   }

   364 #endif  // CLD_DUMP_KLASSES

   365 #undef CLD_DUMP_KLASSES

   366   if (_jmethod_ids != NULL) {

   367     Method::print_jmethod_ids(this, out);

   368   }

   369   out->print_cr("}");

   370 }

   371 #endif // PRODUCT

   372 

   373 void ClassLoaderData::verify() {

   374   oop cl = class_loader();

   375 

   376   guarantee(this == class_loader_data(cl), "Must be the same");

   377   guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data(), "must be");

   378 

   379   // Verify the integrity of the allocated space.

   380   if (metaspace_or_null() != NULL) {

   381     metaspace_or_null()->verify();

   382   }

   383 

   384   for (Klass* k = _klasses; k != NULL; k = k->next_link()) {

   385     guarantee(k->class_loader_data() == this, "Must be the same");

   386     k->verify();

   387   }

   388 }

   389 

   390 // GC root of class loader data created.

   391 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;

   392 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;

   393 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;

   394 

   395 

   396 // Add a new class loader data node to the list.  Assign the newly created

   397 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field

   398 ClassLoaderData* ClassLoaderDataGraph::add(ClassLoaderData** cld_addr, Handle loader_data) {

   399   // Not assigned a class loader data yet.

   400   // Create one.

   401   ClassLoaderData* *list_head = &_head;

   402   ClassLoaderData* next = _head;

   403   ClassLoaderData* cld = new ClassLoaderData(loader_data);

   404 

   405   // First, Atomically set it.

   406   ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);

   407   if (old != NULL) {

   408     delete cld;

   409     // Returns the data.

   410     return old;

   411   }

   412 

   413   // We won the race, and therefore the task of adding the data to the list of

   414   // class loader data

   415   do {

   416     cld->set_next(next);

   417     ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);

   418     if (exchanged == next) {

   419       if (TraceClassLoaderData) {

   420         tty->print("[ClassLoaderData: ");

   421         tty->print("create class loader data "PTR_FORMAT, cld);

   422         tty->print(" for instance "PTR_FORMAT" of ", cld->class_loader());

   423         loader_data->klass()->name()->print_symbol_on(tty);

   424         tty->print_cr("]");

   425       }

   426       return cld;

   427     }

   428     next = exchanged;

   429   } while (true);

   430 }

   431 

   432 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {

   433   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {

   434     cld->oops_do(f, klass_closure, must_claim);

   435   }

   436 }

   437 

   438 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {

   439   if (ClassUnloading) {

   440     ClassLoaderData::the_null_class_loader_data()->oops_do(f, klass_closure, must_claim);

   441   } else {

   442     ClassLoaderDataGraph::oops_do(f, klass_closure, must_claim);

   443   }

   444 }

   445 

   446 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {

   447   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {

   448     cld->classes_do(klass_closure);

   449   }

   450 }

   451 

   452 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {

   453   assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");

   454 

   455   GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();

   456 

   457   // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);

   458   ClassLoaderData* curr = _head;

   459   while (curr != _saved_head) {

   460     if (!curr->claimed()) {

   461       array->push(curr);

   462 

   463       if (TraceClassLoaderData) {

   464         tty->print("[ClassLoaderData] found new CLD: ");

   465         curr->print_value_on(tty);

   466         tty->cr();

   467       }

   468     }

   469 

   470     curr = curr->_next;

   471   }

   472 

   473   return array;

   474 }

   475 

   476 #ifndef PRODUCT

   477 // for debugging and hsfind(x)

   478 bool ClassLoaderDataGraph::contains(address x) {

   479   // I think we need the _metaspace_lock taken here because the class loader

   480   // data graph could be changing while we are walking it (new entries added,

   481   // new entries being unloaded, etc).

   482   if (DumpSharedSpaces) {

   483     // There are only two metaspaces to worry about.

   484     ClassLoaderData* ncld = ClassLoaderData::the_null_class_loader_data();

   485     return (ncld->ro_metaspace()->contains(x) || ncld->rw_metaspace()->contains(x));

   486   }

   487 

   488   if (UseSharedSpaces && MetaspaceShared::is_in_shared_space(x)) {

   489     return true;

   490   }

   491 

   492   for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {

   493     if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {

   494       return true;

   495     }

   496   }

   497 

   498   // Could also be on an unloading list which is okay, ie. still allocated

   499   // for a little while.

   500   for (ClassLoaderData* ucld = _unloading; ucld != NULL; ucld = ucld->next()) {

   501     if (ucld->metaspace_or_null() != NULL && ucld->metaspace_or_null()->contains(x)) {

   502       return true;

   503     }

   504   }

   505   return false;

   506 }

   507 

   508 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {

   509   for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {

   510     if (loader_data == data) {

   511       return true;

   512     }

   513   }

   514 

   515   return false;

   516 }

   517 #endif // PRODUCT

   518 

   519 // Move class loader data from main list to the unloaded list for unloading

   520 // and deallocation later.

   521 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive) {

   522   ClassLoaderData* data = _head;

   523   ClassLoaderData* prev = NULL;

   524   bool seen_dead_loader = false;

   525   // mark metadata seen on the stack and code cache so we can delete

   526   // unneeded entries.

   527   bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();

   528   MetadataOnStackMark md_on_stack;

   529   while (data != NULL) {

   530     if (data->class_loader() == NULL || is_alive->do_object_b(data->class_loader())) {

   531       assert(data->claimed(), "class loader data must have been claimed");

   532       if (has_redefined_a_class) {

   533         data->classes_do(InstanceKlass::purge_previous_versions);

   534       }

   535       data->free_deallocate_list();

   536       prev = data;

   537       data = data->next();

   538       continue;

   539     }

   540     seen_dead_loader = true;

   541     ClassLoaderData* dead = data;

   542     dead->mark_for_unload();

   543     if (TraceClassLoaderData) {

   544       tty->print("[ClassLoaderData: unload loader data "PTR_FORMAT, dead);

   545       tty->print(" for instance "PTR_FORMAT" of ", dead->class_loader());

   546       dead->class_loader()->klass()->name()->print_symbol_on(tty);

   547       tty->print_cr("]");

   548     }

   549     data = data->next();

   550     // Remove from loader list.

   551     if (prev != NULL) {

   552       prev->set_next(data);

   553     } else {

   554       assert(dead == _head, "sanity check");

   555       _head = data;

   556     }

   557     dead->set_next(_unloading);

   558     _unloading = dead;

   559   }

   560   return seen_dead_loader;

   561 }

   562 

   563 void ClassLoaderDataGraph::purge() {

   564   ClassLoaderData* list = _unloading;

   565   _unloading = NULL;

   566   ClassLoaderData* next = list;

   567   while (next != NULL) {

   568     ClassLoaderData* purge_me = next;

   569     next = purge_me->next();

   570     delete purge_me;

   571   }

   572 }

   573 

   574 // CDS support

   575 

   576 // Global metaspaces for writing information to the shared archive.  When

   577 // application CDS is supported, we may need one per metaspace, so this

   578 // sort of looks like it.

   579 Metaspace* ClassLoaderData::_ro_metaspace = NULL;

   580 Metaspace* ClassLoaderData::_rw_metaspace = NULL;

   581 static bool _shared_metaspaces_initialized = false;

   582 

   583 // Initialize shared metaspaces (change to call from somewhere not lazily)

   584 void ClassLoaderData::initialize_shared_metaspaces() {

   585   assert(DumpSharedSpaces, "only use this for dumping shared spaces");

   586   assert(this == ClassLoaderData::the_null_class_loader_data(),

   587          "only supported for null loader data for now");

   588   assert (!_shared_metaspaces_initialized, "only initialize once");

   589   MutexLockerEx ml(metaspace_lock(),  Mutex::_no_safepoint_check_flag);

   590   _ro_metaspace = new Metaspace(_metaspace_lock, SharedReadOnlySize/wordSize);

   591   _rw_metaspace = new Metaspace(_metaspace_lock, SharedReadWriteSize/wordSize);

   592   _shared_metaspaces_initialized = true;

   593 }

   594 

   595 Metaspace* ClassLoaderData::ro_metaspace() {

   596   assert(_ro_metaspace != NULL, "should already be initialized");

   597   return _ro_metaspace;

   598 }

   599 

   600 Metaspace* ClassLoaderData::rw_metaspace() {

   601   assert(_rw_metaspace != NULL, "should already be initialized");

   602   return _rw_metaspace;

   603 }

   604 

   605 

   606 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {

   607   _data = ClassLoaderDataGraph::_head;

   608 }

   609 

   610 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}

   611 

   612 #ifndef PRODUCT

   613 // callable from debugger

   614 extern "C" int print_loader_data_graph() {

   615   ClassLoaderDataGraph::dump_on(tty);

   616   return 0;

   617 }

   618 

   619 void ClassLoaderDataGraph::verify() {

   620   for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {

   621     data->verify();

   622   }

   623 }

   624 

   625 void ClassLoaderDataGraph::dump_on(outputStream * const out) {

   626   for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {

   627     data->dump(out);

   628   }

   629   MetaspaceAux::dump(out);

   630 }

   631 

   632 void ClassLoaderData::print_value_on(outputStream* out) const {

   633   if (class_loader() == NULL) {

   634     out->print_cr("NULL class_loader");

   635   } else {

   636     out->print("class loader "PTR_FORMAT, this);

   637     class_loader()->print_value_on(out);

   638   }

   639 }

   640 #endif // PRODUCT