51 #include "classfile/classLoaderDataGraph.inline.hpp"
52 #include "classfile/dictionary.hpp"
53 #include "classfile/javaClasses.hpp"
54 #include "classfile/moduleEntry.hpp"
55 #include "classfile/packageEntry.hpp"
56 #include "classfile/symbolTable.hpp"
57 #include "classfile/systemDictionary.hpp"
58 #include "classfile/vmClasses.hpp"
59 #include "logging/log.hpp"
60 #include "logging/logStream.hpp"
61 #include "memory/allocation.inline.hpp"
62 #include "memory/classLoaderMetaspace.hpp"
63 #include "memory/metadataFactory.hpp"
64 #include "memory/metaspace.hpp"
65 #include "memory/resourceArea.hpp"
66 #include "memory/universe.hpp"
67 #include "oops/access.inline.hpp"
68 #include "oops/klass.inline.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "oops/oopHandle.inline.hpp"
71 #include "oops/weakHandle.inline.hpp"
72 #include "runtime/arguments.hpp"
73 #include "runtime/atomic.hpp"
74 #include "runtime/handles.inline.hpp"
75 #include "runtime/mutex.hpp"
76 #include "runtime/safepoint.hpp"
77 #include "utilities/growableArray.hpp"
78 #include "utilities/macros.hpp"
79 #include "utilities/ostream.hpp"
80
81 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
82
83 void ClassLoaderData::init_null_class_loader_data() {
84 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
85 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
86
87 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
88 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
89 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
90
360 #ifdef ASSERT
361 oop m = k->java_mirror();
362 assert(m != NULL, "NULL mirror");
363 assert(m->is_a(vmClasses::Class_klass()), "invalid mirror");
364 #endif
365 klass_closure->do_klass(k);
366 }
367 }
368 }
369
370 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
371 // Lock-free access requires load_acquire
372 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
373 if (k->is_instance_klass()) {
374 f(InstanceKlass::cast(k));
375 }
376 assert(k != k->next_link(), "no loops!");
377 }
378 }
379
380 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
381 assert_locked_or_safepoint(Module_lock);
382 if (_unnamed_module != NULL) {
383 f(_unnamed_module);
384 }
385 if (_modules != NULL) {
386 for (int i = 0; i < _modules->table_size(); i++) {
387 for (ModuleEntry* entry = _modules->bucket(i);
388 entry != NULL;
389 entry = entry->next()) {
390 f(entry);
391 }
392 }
393 }
394 }
395
396 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
397 assert_locked_or_safepoint(Module_lock);
398 if (_packages != NULL) {
399 for (int i = 0; i < _packages->table_size(); i++) {
526 }
527 ShouldNotReachHere(); // should have found this class!!
528 }
529
530 void ClassLoaderData::unload() {
531 _unloading = true;
532
533 LogTarget(Trace, class, loader, data) lt;
534 if (lt.is_enabled()) {
535 ResourceMark rm;
536 LogStream ls(lt);
537 ls.print("unload");
538 print_value_on(&ls);
539 ls.cr();
540 }
541
542 // Some items on the _deallocate_list need to free their C heap structures
543 // if they are not already on the _klasses list.
544 free_deallocate_list_C_heap_structures();
545
546 // Clean up class dependencies and tell serviceability tools
547 // these classes are unloading. Must be called
548 // after erroneous classes are released.
549 classes_do(InstanceKlass::unload_class);
550
551 // Method::clear_jmethod_ids only sets the jmethod_ids to NULL without
552 // releasing the memory for related JNIMethodBlocks and JNIMethodBlockNodes.
553 // This is done intentionally because native code (e.g. JVMTI agent) holding
554 // jmethod_ids may access them after the associated classes and class loader
555 // are unloaded. The Java Native Interface Specification says "method ID
556 // does not prevent the VM from unloading the class from which the ID has
557 // been derived. After the class is unloaded, the method or field ID becomes
558 // invalid". In real world usages, the native code may rely on jmethod_ids
559 // being NULL after class unloading. Hence, it is unsafe to free the memory
560 // from the VM side without knowing when native code is going to stop using
561 // them.
562 if (_jmethod_ids != NULL) {
563 Method::clear_jmethod_ids(this);
564 }
565
828 void ClassLoaderData::free_deallocate_list() {
829 // This must be called at a safepoint because it depends on metadata walking at
830 // safepoint cleanup time.
831 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
832 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
833 if (_deallocate_list == NULL) {
834 return;
835 }
836 // Go backwards because this removes entries that are freed.
837 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
838 Metadata* m = _deallocate_list->at(i);
839 if (!m->on_stack()) {
840 _deallocate_list->remove_at(i);
841 // There are only three types of metadata that we deallocate directly.
842 // Cast them so they can be used by the template function.
843 if (m->is_method()) {
844 MetadataFactory::free_metadata(this, (Method*)m);
845 } else if (m->is_constantPool()) {
846 MetadataFactory::free_metadata(this, (ConstantPool*)m);
847 } else if (m->is_klass()) {
848 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
849 } else {
850 ShouldNotReachHere();
851 }
852 } else {
853 // Metadata is alive.
854 // If scratch_class is on stack then it shouldn't be on this list!
855 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
856 "scratch classes on this list should be dead");
857 // Also should assert that other metadata on the list was found in handles.
858 // Some cleaning remains.
859 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
860 }
861 }
862 }
863
864 // This is distinct from free_deallocate_list. For class loader data that are
865 // unloading, this frees the C heap memory for items on the list, and unlinks
866 // scratch or error classes so that unloading events aren't triggered for these
867 // classes. The metadata is removed with the unloading metaspace.
868 // There isn't C heap memory allocated for methods, so nothing is done for them.
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51 #include "classfile/classLoaderDataGraph.inline.hpp"
52 #include "classfile/dictionary.hpp"
53 #include "classfile/javaClasses.hpp"
54 #include "classfile/moduleEntry.hpp"
55 #include "classfile/packageEntry.hpp"
56 #include "classfile/symbolTable.hpp"
57 #include "classfile/systemDictionary.hpp"
58 #include "classfile/vmClasses.hpp"
59 #include "logging/log.hpp"
60 #include "logging/logStream.hpp"
61 #include "memory/allocation.inline.hpp"
62 #include "memory/classLoaderMetaspace.hpp"
63 #include "memory/metadataFactory.hpp"
64 #include "memory/metaspace.hpp"
65 #include "memory/resourceArea.hpp"
66 #include "memory/universe.hpp"
67 #include "oops/access.inline.hpp"
68 #include "oops/klass.inline.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "oops/oopHandle.inline.hpp"
71 #include "oops/inlineKlass.inline.hpp"
72 #include "oops/weakHandle.inline.hpp"
73 #include "runtime/arguments.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/handles.inline.hpp"
76 #include "runtime/mutex.hpp"
77 #include "runtime/safepoint.hpp"
78 #include "utilities/growableArray.hpp"
79 #include "utilities/macros.hpp"
80 #include "utilities/ostream.hpp"
81
82 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
83
84 void ClassLoaderData::init_null_class_loader_data() {
85 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
86 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
87
88 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
89 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
90 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
91
361 #ifdef ASSERT
362 oop m = k->java_mirror();
363 assert(m != NULL, "NULL mirror");
364 assert(m->is_a(vmClasses::Class_klass()), "invalid mirror");
365 #endif
366 klass_closure->do_klass(k);
367 }
368 }
369 }
370
371 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
372 // Lock-free access requires load_acquire
373 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
374 if (k->is_instance_klass()) {
375 f(InstanceKlass::cast(k));
376 }
377 assert(k != k->next_link(), "no loops!");
378 }
379 }
380
381 void ClassLoaderData::inline_classes_do(void f(InlineKlass*)) {
382 // Lock-free access requires load_acquire
383 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
384 if (k->is_inline_klass()) {
385 f(InlineKlass::cast(k));
386 }
387 assert(k != k->next_link(), "no loops!");
388 }
389 }
390
391 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
392 assert_locked_or_safepoint(Module_lock);
393 if (_unnamed_module != NULL) {
394 f(_unnamed_module);
395 }
396 if (_modules != NULL) {
397 for (int i = 0; i < _modules->table_size(); i++) {
398 for (ModuleEntry* entry = _modules->bucket(i);
399 entry != NULL;
400 entry = entry->next()) {
401 f(entry);
402 }
403 }
404 }
405 }
406
407 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
408 assert_locked_or_safepoint(Module_lock);
409 if (_packages != NULL) {
410 for (int i = 0; i < _packages->table_size(); i++) {
537 }
538 ShouldNotReachHere(); // should have found this class!!
539 }
540
541 void ClassLoaderData::unload() {
542 _unloading = true;
543
544 LogTarget(Trace, class, loader, data) lt;
545 if (lt.is_enabled()) {
546 ResourceMark rm;
547 LogStream ls(lt);
548 ls.print("unload");
549 print_value_on(&ls);
550 ls.cr();
551 }
552
553 // Some items on the _deallocate_list need to free their C heap structures
554 // if they are not already on the _klasses list.
555 free_deallocate_list_C_heap_structures();
556
557 inline_classes_do(InlineKlass::cleanup);
558
559 // Clean up class dependencies and tell serviceability tools
560 // these classes are unloading. Must be called
561 // after erroneous classes are released.
562 classes_do(InstanceKlass::unload_class);
563
564 // Method::clear_jmethod_ids only sets the jmethod_ids to NULL without
565 // releasing the memory for related JNIMethodBlocks and JNIMethodBlockNodes.
566 // This is done intentionally because native code (e.g. JVMTI agent) holding
567 // jmethod_ids may access them after the associated classes and class loader
568 // are unloaded. The Java Native Interface Specification says "method ID
569 // does not prevent the VM from unloading the class from which the ID has
570 // been derived. After the class is unloaded, the method or field ID becomes
571 // invalid". In real world usages, the native code may rely on jmethod_ids
572 // being NULL after class unloading. Hence, it is unsafe to free the memory
573 // from the VM side without knowing when native code is going to stop using
574 // them.
575 if (_jmethod_ids != NULL) {
576 Method::clear_jmethod_ids(this);
577 }
578
841 void ClassLoaderData::free_deallocate_list() {
842 // This must be called at a safepoint because it depends on metadata walking at
843 // safepoint cleanup time.
844 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
845 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
846 if (_deallocate_list == NULL) {
847 return;
848 }
849 // Go backwards because this removes entries that are freed.
850 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
851 Metadata* m = _deallocate_list->at(i);
852 if (!m->on_stack()) {
853 _deallocate_list->remove_at(i);
854 // There are only three types of metadata that we deallocate directly.
855 // Cast them so they can be used by the template function.
856 if (m->is_method()) {
857 MetadataFactory::free_metadata(this, (Method*)m);
858 } else if (m->is_constantPool()) {
859 MetadataFactory::free_metadata(this, (ConstantPool*)m);
860 } else if (m->is_klass()) {
861 if (!((Klass*)m)->is_inline_klass()) {
862 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
863 } else {
864 MetadataFactory::free_metadata(this, (InlineKlass*)m);
865 }
866 } else {
867 ShouldNotReachHere();
868 }
869 } else {
870 // Metadata is alive.
871 // If scratch_class is on stack then it shouldn't be on this list!
872 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
873 "scratch classes on this list should be dead");
874 // Also should assert that other metadata on the list was found in handles.
875 // Some cleaning remains.
876 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
877 }
878 }
879 }
880
881 // This is distinct from free_deallocate_list. For class loader data that are
882 // unloading, this frees the C heap memory for items on the list, and unlinks
883 // scratch or error classes so that unloading events aren't triggered for these
884 // classes. The metadata is removed with the unloading metaspace.
885 // There isn't C heap memory allocated for methods, so nothing is done for them.
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