jdk8-mips64-public/hotspot: src/share/vm/classfile/dictionary.cpp@1f9994892f89 (annotated)

src/share/vm/classfile/dictionary.cpp@1f9994892f89 (annotated)

src/share/vm/classfile/dictionary.cpp

Thu, 21 Feb 2013 17:22:15 +0100

author: stefank
date: Thu, 21 Feb 2013 17:22:15 +0100
changeset 4667: 1f9994892f89
parent 4304: 90273fc0a981
child 4981: d587a5c30bd8
permissions: -rw-r--r--

8008549: NPG: SystemDictionary::find(...) unnecessarily keeps class loaders alive
Summary: SystemDictionary::find(...) should not create and register ClassLoaderData objects for class loaders.
Reviewed-by: coleenp, acorn
Contributed-by: Stefan Karlsson <stefan.karlsson@oracle.com>, Erik Helin <erik.helin@oracle.com>

 /*
  * Copyright (c) 2003, 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.
  *
  */
 #include "precompiled.hpp"
 #include "classfile/dictionary.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "oops/oop.inline.hpp"
 #include "prims/jvmtiRedefineClassesTrace.hpp"
 #include "services/classLoadingService.hpp"
 #include "utilities/hashtable.inline.hpp"
 DictionaryEntry*  Dictionary::_current_class_entry = NULL;
 int               Dictionary::_current_class_index =    0;
 Dictionary::Dictionary(int table_size)
   : TwoOopHashtable<Klass*, mtClass>(table_size, sizeof(DictionaryEntry)) {
   _current_class_index = 0;
   _current_class_entry = NULL;
 };
 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t,
                        int number_of_entries)
   : TwoOopHashtable<Klass*, mtClass>(table_size, sizeof(DictionaryEntry), t, number_of_entries) {
   _current_class_index = 0;
   _current_class_entry = NULL;
 };
 DictionaryEntry* Dictionary::new_entry(unsigned int hash, Klass* klass,
                                        ClassLoaderData* loader_data) {
   DictionaryEntry* entry = (DictionaryEntry*)Hashtable<Klass*, mtClass>::new_entry(hash, klass);
   entry->set_loader_data(loader_data);
   entry->set_pd_set(NULL);
   assert(klass->oop_is_instance(), "Must be");
   return entry;
 }
 void Dictionary::free_entry(DictionaryEntry* entry) {
   // avoid recursion when deleting linked list
   while (entry->pd_set() != NULL) {
     ProtectionDomainEntry* to_delete = entry->pd_set();
     entry->set_pd_set(to_delete->next());
     delete to_delete;
   }
   Hashtable<Klass*, mtClass>::free_entry(entry);
 }
 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
 #ifdef ASSERT
   if (protection_domain == InstanceKlass::cast(klass())->protection_domain()) {
     // Ensure this doesn't show up in the pd_set (invariant)
     bool in_pd_set = false;
     for (ProtectionDomainEntry* current = _pd_set;
                                 current != NULL;
                                 current = current->next()) {
       if (current->protection_domain() == protection_domain) {
         in_pd_set = true;
         break;
       }
     }
     if (in_pd_set) {
       assert(false, "A klass's protection domain should not show up "
                     "in its sys. dict. PD set");
     }
   }
 #endif /* ASSERT */
   if (protection_domain == InstanceKlass::cast(klass())->protection_domain()) {
     // Succeeds trivially
     return true;
   }
   for (ProtectionDomainEntry* current = _pd_set;
                               current != NULL;
                               current = current->next()) {
     if (current->protection_domain() == protection_domain) return true;
   }
   return false;
 }
 void DictionaryEntry::add_protection_domain(oop protection_domain) {
   assert_locked_or_safepoint(SystemDictionary_lock);
   if (!contains_protection_domain(protection_domain)) {
     ProtectionDomainEntry* new_head =
                 new ProtectionDomainEntry(protection_domain, _pd_set);
     // Warning: Preserve store ordering.  The SystemDictionary is read
     //          without locks.  The new ProtectionDomainEntry must be
     //          complete before other threads can be allowed to see it
     //          via a store to _pd_set.
     OrderAccess::release_store_ptr(&_pd_set, new_head);
   }
   if (TraceProtectionDomainVerification && WizardMode) {
     print();
   }
 }
 bool Dictionary::do_unloading() {
   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
   bool class_was_unloaded = false;
   int  index = 0; // Defined here for portability! Do not move
   // Remove unloadable entries and classes from system dictionary
   // The placeholder array has been handled in always_strong_oops_do.
   DictionaryEntry* probe = NULL;
   for (index = 0; index < table_size(); index++) {
     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
       probe = *p;
       Klass* e = probe->klass();
       ClassLoaderData* loader_data = probe->loader_data();
       InstanceKlass* ik = InstanceKlass::cast(e);
       // Non-unloadable classes were handled in always_strong_oops_do
       if (!is_strongly_reachable(loader_data, e)) {
         // Entry was not visited in phase1 (negated test from phase1)
         assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
         ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
         // Do we need to delete this system dictionary entry?
         bool purge_entry = false;
         // Do we need to delete this system dictionary entry?
         if (loader_data->is_unloading()) {
           // If the loader is not live this entry should always be
           // removed (will never be looked up again). Note that this is
           // not the same as unloading the referred class.
           if (k_def_class_loader_data == loader_data) {
             // This is the defining entry, so the referred class is about
             // to be unloaded.
             // Notify the debugger and clean up the class.
             class_was_unloaded = true;
             // notify the debugger
             if (JvmtiExport::should_post_class_unload()) {
               JvmtiExport::post_class_unload(ik);
             }
             // notify ClassLoadingService of class unload
             ClassLoadingService::notify_class_unloaded(ik);
             // Clean up C heap
             ik->release_C_heap_structures();
             ik->constants()->release_C_heap_structures();
           }
           // Also remove this system dictionary entry.
           purge_entry = true;
         } else {
           // The loader in this entry is alive. If the klass is dead,
           // (determined by checking the defining class loader)
           // the loader must be an initiating loader (rather than the
           // defining loader). Remove this entry.
           if (k_def_class_loader_data->is_unloading()) {
             // If we get here, the class_loader_data must not be the defining
             // loader, it must be an initiating one.
             assert(k_def_class_loader_data != loader_data,
                    "cannot have live defining loader and unreachable klass");
             // Loader is live, but class and its defining loader are dead.
             // Remove the entry. The class is going away.
             purge_entry = true;
           }
         }
         if (purge_entry) {
           *p = probe->next();
           if (probe == _current_class_entry) {
             _current_class_entry = NULL;
           }
           free_entry(probe);
           continue;
         }
       }
       p = probe->next_addr();
     }
   }
   return class_was_unloaded;
 }
 void Dictionary::always_strong_oops_do(OopClosure* blk) {
   // Follow all system classes and temporary placeholders in dictionary
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry *probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* e = probe->klass();
       ClassLoaderData* loader_data = probe->loader_data();
       if (is_strongly_reachable(loader_data, e)) {
         probe->protection_domain_set_oops_do(blk);
       }
     }
   }
 }
 void Dictionary::always_strong_classes_do(KlassClosure* closure) {
   // Follow all system classes and temporary placeholders in dictionary
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* e = probe->klass();
       ClassLoaderData* loader_data = probe->loader_data();
       if (is_strongly_reachable(loader_data, e)) {
         closure->do_klass(e);
       }
     }
   }
 }
 //   Just the classes from defining class loaders
 void Dictionary::classes_do(void f(Klass*)) {
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* k = probe->klass();
       if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
         f(k);
       }
     }
   }
 }
 // Added for initialize_itable_for_klass to handle exceptions
 //   Just the classes from defining class loaders
 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* k = probe->klass();
       if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
         f(k, CHECK);
       }
     }
   }
 }
 //   All classes, and their class loaders
 //   (added for helpers that use HandleMarks and ResourceMarks)
 // Don't iterate over placeholders
 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*, TRAPS), TRAPS) {
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* k = probe->klass();
       f(k, probe->loader_data(), CHECK);
     }
   }
 }
 //   All classes, and their class loaders
 // Don't iterate over placeholders
 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* k = probe->klass();
       f(k, probe->loader_data());
     }
   }
 }
 void Dictionary::oops_do(OopClosure* f) {
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       probe->protection_domain_set_oops_do(f);
     }
   }
 }
 void Dictionary::methods_do(void f(Method*)) {
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* k = probe->klass();
       if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
         // only take klass is we have the entry with the defining class loader
         InstanceKlass::cast(k)->methods_do(f);
       }
     }
   }
 }
 Klass* Dictionary::try_get_next_class() {
   while (true) {
     if (_current_class_entry != NULL) {
       Klass* k = _current_class_entry->klass();
       _current_class_entry = _current_class_entry->next();
       return k;
     }
     _current_class_index = (_current_class_index + 1) % table_size();
     _current_class_entry = bucket(_current_class_index);
   }
   // never reached
 }
 // Add a loaded class to the system dictionary.
 // Readers of the SystemDictionary aren't always locked, so _buckets
 // is volatile. The store of the next field in the constructor is
 // also cast to volatile;  we do this to ensure store order is maintained
 // by the compilers.
 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data,
                            KlassHandle obj) {
   assert_locked_or_safepoint(SystemDictionary_lock);
   assert(obj() != NULL, "adding NULL obj");
   assert(obj()->name() == class_name, "sanity check on name");
   assert(loader_data != NULL, "Must be non-NULL");
   unsigned int hash = compute_hash(class_name, loader_data);
   int index = hash_to_index(hash);
   DictionaryEntry* entry = new_entry(hash, obj(), loader_data);
   add_entry(index, entry);
 }
 // This routine does not lock the system dictionary.
 //
 // Since readers don't hold a lock, we must make sure that system
 // dictionary entries are only removed at a safepoint (when only one
 // thread is running), and are added to in a safe way (all links must
 // be updated in an MT-safe manner).
 //
 // Callers should be aware that an entry could be added just after
 // _buckets[index] is read here, so the caller will not see the new entry.
 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
                                        Symbol* class_name,
                                        ClassLoaderData* loader_data) {
   debug_only(_lookup_count++);
   for (DictionaryEntry* entry = bucket(index);
                         entry != NULL;
                         entry = entry->next()) {
     if (entry->hash() == hash && entry->equals(class_name, loader_data)) {
       return entry;
     }
     debug_only(_lookup_length++);
   }
   return NULL;
 }
 Klass* Dictionary::find(int index, unsigned int hash, Symbol* name,
                           ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
   if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
     return entry->klass();
   } else {
     return NULL;
   }
 }
 Klass* Dictionary::find_class(int index, unsigned int hash,
                                 Symbol* name, ClassLoaderData* loader_data) {
   assert_locked_or_safepoint(SystemDictionary_lock);
   assert (index == index_for(name, loader_data), "incorrect index?");
   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
   return (entry != NULL) ? entry->klass() : (Klass*)NULL;
 }
 // Variant of find_class for shared classes.  No locking required, as
 // that table is static.
 Klass* Dictionary::find_shared_class(int index, unsigned int hash,
                                        Symbol* name) {
   assert (index == index_for(name, NULL), "incorrect index?");
   DictionaryEntry* entry = get_entry(index, hash, name, NULL);
   return (entry != NULL) ? entry->klass() : (Klass*)NULL;
 }
 void Dictionary::add_protection_domain(int index, unsigned int hash,
                                        instanceKlassHandle klass,
                                        ClassLoaderData* loader_data, Handle protection_domain,
                                        TRAPS) {
   Symbol*  klass_name = klass->name();
   DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data);
   assert(entry != NULL,"entry must be present, we just created it");
   assert(protection_domain() != NULL,
          "real protection domain should be present");
   entry->add_protection_domain(protection_domain());
   assert(entry->contains_protection_domain(protection_domain()),
          "now protection domain should be present");
 }
 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
                                             Symbol* name,
                                             ClassLoaderData* loader_data,
                                             Handle protection_domain) {
   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
   return entry->is_valid_protection_domain(protection_domain);
 }
 void Dictionary::reorder_dictionary() {
   // Copy all the dictionary entries into a single master list.
   DictionaryEntry* master_list = NULL;
   for (int i = 0; i < table_size(); ++i) {
     DictionaryEntry* p = bucket(i);
     while (p != NULL) {
       DictionaryEntry* tmp;
       tmp = p->next();
       p->set_next(master_list);
       master_list = p;
       p = tmp;
     }
     set_entry(i, NULL);
   }
   // Add the dictionary entries back to the list in the correct buckets.
   while (master_list != NULL) {
     DictionaryEntry* p = master_list;
     master_list = master_list->next();
     p->set_next(NULL);
     Symbol* class_name = InstanceKlass::cast((Klass*)(p->klass()))->name();
     // Since the null class loader data isn't copied to the CDS archive,
     // compute the hash with NULL for loader data.
     unsigned int hash = compute_hash(class_name, NULL);
     int index = hash_to_index(hash);
     p->set_hash(hash);
     p->set_loader_data(NULL);   // loader_data isn't copied to CDS
     p->set_next(bucket(index));
     set_entry(index, p);
   }
 }
 SymbolPropertyTable::SymbolPropertyTable(int table_size)
   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
 {
 }
 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
                                          int number_of_entries)
   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
 {
 }
 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
                                                      Symbol* sym,
                                                      intptr_t sym_mode) {
   assert(index == index_for(sym, sym_mode), "incorrect index?");
   for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
     if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
       return p;
     }
   }
   return NULL;
 }
 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
                                                     Symbol* sym, intptr_t sym_mode) {
   assert_locked_or_safepoint(SystemDictionary_lock);
   assert(index == index_for(sym, sym_mode), "incorrect index?");
   assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
   SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
   Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
   return p;
 }
 void SymbolPropertyTable::oops_do(OopClosure* f) {
   for (int index = 0; index < table_size(); index++) {
     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
       if (p->method_type() != NULL) {
         f->do_oop(p->method_type_addr());
       }
     }
   }
 }
 void SymbolPropertyTable::methods_do(void f(Method*)) {
   for (int index = 0; index < table_size(); index++) {
     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
       Method* prop = p->method();
       if (prop != NULL) {
         f((Method*)prop);
       }
     }
   }
 }
 // ----------------------------------------------------------------------------
 #ifndef PRODUCT
 void Dictionary::print() {
   ResourceMark rm;
   HandleMark   hm;
   tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
                  table_size(), number_of_entries());
   tty->print_cr("^ indicates that initiating loader is different from "
                 "defining loader");
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       if (Verbose) tty->print("%4d: ", index);
       Klass* e = probe->klass();
       ClassLoaderData* loader_data =  probe->loader_data();
       bool is_defining_class =
          (loader_data == InstanceKlass::cast(e)->class_loader_data());
       tty->print("%s%s", is_defining_class ? " " : "^",
                    e->external_name());
         tty->print(", loader ");
       loader_data->print_value();
       tty->cr();
     }
   }
 }
 #endif
 void Dictionary::verify() {
   guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
   int element_count = 0;
   for (int index = 0; index < table_size(); index++) {
     for (DictionaryEntry* probe = bucket(index);
                           probe != NULL;
                           probe = probe->next()) {
       Klass* e = probe->klass();
       ClassLoaderData* loader_data = probe->loader_data();
       guarantee(e->oop_is_instance(),
                               "Verify of system dictionary failed");
       // class loader must be present;  a null class loader is the
       // boostrap loader
       guarantee(loader_data != NULL || DumpSharedSpaces ||
                 loader_data->class_loader() == NULL ||
                 loader_data->class_loader()->is_instance(),
                 "checking type of class_loader");
       e->verify();
       probe->verify_protection_domain_set();
       element_count++;
     }
   }
   guarantee(number_of_entries() == element_count,
             "Verify of system dictionary failed");
   debug_only(verify_lookup_length((double)number_of_entries() / table_size()));
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/classfile/dictionary.cpp@1f9994892f89 (annotated)

src/share/vm/classfile/dictionary.cpp