Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2012, 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

 // extension, 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/javaClasses.hpp"

 #include "classfile/systemDictionary.hpp"

 #include "code/codeCache.hpp"

 #include "memory/metadataFactory.hpp"

 #include "memory/metaspaceShared.hpp"

 #include "prims/jvmtiRedefineClasses.hpp"

 #include "runtime/jniHandles.hpp"

 #include "runtime/mutex.hpp"

 #include "runtime/safepoint.hpp"

 #include "runtime/synchronizer.hpp"

 #include "utilities/growableArray.hpp"

 #include "utilities/ostream.hpp"

 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;

 ClassLoaderData::ClassLoaderData(Handle h_class_loader) : _class_loader(h_class_loader()),

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

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

   _deallocate_list(NULL), _next(NULL),

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

     // empty

 }

 bool ClassLoaderData::claim() {

   if (_claimed == 1) {

     return false;

   }

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

 }

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

   if (must_claim && !claim()) {

     return;

   }

   f->do_oop(&_class_loader);

   _handles->oops_do(f);

   if (klass_closure != NULL) {

     classes_do(klass_closure);

   }

 }

 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {

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

     klass_closure->do_klass(k);

   }

 }

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

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

     if (k->oop_is_instance()) {

       f(InstanceKlass::cast(k));

     }

   }

 }

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

   ClassLoaderData * const from_cld = this;

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

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

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

     return;

   }

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

   oop to = to_cld->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

   from_cld->add_dependency(to_cld, CHECK);

 }

 bool ClassLoaderData::has_dependency(ClassLoaderData* dependency) {

   oop loader = dependency->class_loader();

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

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

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

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

   while (ok != NULL) {

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

       return true;

     }

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

   }

   return false;

 }

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

   // Minimize the number of duplicates in the list.

   if (has_dependency(dependency)) {

     return;

   }

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

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

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

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

   // Do the barrier first.

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

   while (true) {

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

     deps->obj_at_put(1, old_dependency);

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

     if (newold == old_dependency) {

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

       // we won the race to add this dependency

       break;

     }

   }

 }

 void ClassLoaderDataGraph::clear_claimed_marks() {

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

     cld->clear_claimed();

   }

 }

 void ClassLoaderData::add_class(Klass* k) {

   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

   _klasses = k;

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

     ResourceMark rm;

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

                   PTR_FORMAT " loader: " PTR_FORMAT " %s",

                   k,

                   k->external_name(),

                   k->class_loader_data(),

                   k->class_loader(),

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

       );

   }

 }

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

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

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

 void ClassLoaderData::remove_class(Klass* scratch_class) {

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

   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;

   }

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

 }

 ClassLoaderData::~ClassLoaderData() {

   Metaspace *m = _metaspace;

   if (m != NULL) {

     _metaspace = NULL;

     // release the metaspace

     delete m;

     // release the handles

     if (_handles != NULL) {

       JNIHandleBlock::release_block(_handles);

       _handles = NULL;

     }

   }

   // 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;

   }

 }

 Metaspace* ClassLoaderData::metaspace_non_null() {

   // 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.

   if (_metaspace == NULL) {

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

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

     if (_metaspace != NULL) {

       return _metaspace;

     }

     if (class_loader() == NULL) {

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

       size_t word_size = Metaspace::first_chunk_word_size();

       set_metaspace(new Metaspace(_metaspace_lock, word_size));

     } else {

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

     }

   }

   return _metaspace;

 }

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

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

 jobject ClassLoaderData::add_handle(Handle h) {

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

   if (handles() == NULL) {

     set_handles(JNIHandleBlock::allocate_block());

   }

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

 }

 // 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<Metadata*>(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();

       }

     }

   }

 }

 #ifndef PRODUCT

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

   oop class_loader = loader_data->class_loader();

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

 }

 // Define to dump klasses

 #undef CLD_DUMP_KLASSES

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

   ResourceMark rm;

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

       this, class_loader(),

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

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

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

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

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

   out->cr();

   if (metaspace_or_null() != NULL) {

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

     metaspace_or_null()->dump(out);

   } else {

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

   }

 #ifdef CLD_DUMP_KLASSES

   if (Verbose) {

     ResourceMark rm;

     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());

       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() {

   oop cl = class_loader();

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

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

   }

 }

 // GC root of class loader data created.

 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;

 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;

 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;

 // 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(ClassLoaderData** cld_addr, Handle loader_data) {

   // Not assigned a class loader data yet.

   // Create one.

   ClassLoaderData* *list_head = &_head;

   ClassLoaderData* next = _head;

   ClassLoaderData* cld = new ClassLoaderData(loader_data);

   // 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

   do {

     cld->set_next(next);

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

     if (exchanged == next) {

       if (TraceClassLoaderData) {

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

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

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

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

         tty->print_cr("]");

       }

       return cld;

     }

     next = exchanged;

   } while (true);

 }

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

   if (ClassUnloading) {

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

   } else {

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

   }

 }

 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {

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

     cld->classes_do(klass_closure);

   }

 }

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

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

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

   // 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 (TraceClassLoaderData) {

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

         curr->print_value_on(tty);

         tty->cr();

       }

     }

     curr = curr->_next;

   }

   return array;

 }

 #ifndef PRODUCT

 // for debugging and hsfind(x)

 bool ClassLoaderDataGraph::contains(address x) {

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

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

   // new entries being unloaded, etc).

   if (DumpSharedSpaces) {

     // There are only two metaspaces to worry about.

     ClassLoaderData* ncld = ClassLoaderData::the_null_class_loader_data();

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

   }

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

     return true;

   }

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

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

       return true;

     }

   }

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

   // for a little while.

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

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

       return true;

     }

   }

   return false;

 }

 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) {

   ClassLoaderData* data = _head;

   ClassLoaderData* prev = NULL;

   bool seen_dead_loader = false;

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

   // unneeded entries.

   bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();

   MetadataOnStackMark md_on_stack;

   while (data != NULL) {

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

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

       if (has_redefined_a_class) {

         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->mark_for_unload();

     if (TraceClassLoaderData) {

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

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

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

       tty->print_cr("]");

     }

     data = data->next();

     // Remove from loader list.

     if (prev != NULL) {

       prev->set_next(data);

     } else {

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

       _head = data;

     }

     dead->set_next(_unloading);

     _unloading = dead;

   }

   return seen_dead_loader;

 }

 void ClassLoaderDataGraph::purge() {

   ClassLoaderData* list = _unloading;

   _unloading = NULL;

   ClassLoaderData* next = list;

   while (next != NULL) {

     ClassLoaderData* purge_me = next;

     next = purge_me->next();

     delete purge_me;

   }

 }

 // 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, SharedReadOnlySize/wordSize);

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

   _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;

 }

 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);

 }

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

   if (class_loader() == NULL) {

     out->print_cr("NULL class_loader");

   } else {

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

     class_loader()->print_value_on(out);

   }

 }

 #endif // PRODUCT