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 /*

  * 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<klassOop>(table_size, sizeof(DictionaryEntry)) {

   _current_class_index = 0;

   _current_class_entry = NULL;

 };

 Dictionary::Dictionary(int table_size, HashtableBucket* t,

                        int number_of_entries)

   : TwoOopHashtable<klassOop>(table_size, sizeof(DictionaryEntry), t, number_of_entries) {

   _current_class_index = 0;

   _current_class_entry = NULL;

 };

 DictionaryEntry* Dictionary::new_entry(unsigned int hash, klassOop klass,

                                        oop loader) {

   DictionaryEntry* entry;

   entry = (DictionaryEntry*)Hashtable<klassOop>::new_entry(hash, klass);

   entry->set_loader(loader);

   entry->set_pd_set(NULL);

   return entry;

 }

 DictionaryEntry* Dictionary::new_entry() {

   DictionaryEntry* entry = (DictionaryEntry*)Hashtable<klassOop>::new_entry(0L, NULL);

   entry->set_loader(NULL);

   entry->set_pd_set(NULL);

   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<klassOop>::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(BoolObjectClosure* is_alive) {

   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;

       klassOop e = probe->klass();

       oop class_loader = probe->loader();

       instanceKlass* ik = instanceKlass::cast(e);

       if (ik->previous_versions() != NULL) {

         // This klass has previous versions so see what we can cleanup

         // while it is safe to do so.

         int gc_count = 0;    // leave debugging breadcrumbs

         int live_count = 0;

         // RC_TRACE macro has an embedded ResourceMark

         RC_TRACE(0x00000200, ("unload: %s: previous version length=%d",

           ik->external_name(), ik->previous_versions()->length()));

         for (int i = ik->previous_versions()->length() - 1; i >= 0; i--) {

           // check the previous versions array for GC'ed weak refs

           PreviousVersionNode * pv_node = ik->previous_versions()->at(i);

           jobject cp_ref = pv_node->prev_constant_pool();

           assert(cp_ref != NULL, "cp ref was unexpectedly cleared");

           if (cp_ref == NULL) {

             delete pv_node;

             ik->previous_versions()->remove_at(i);

             // Since we are traversing the array backwards, we don't have to

             // do anything special with the index.

             continue;  // robustness

           }

           constantPoolOop pvcp = (constantPoolOop)JNIHandles::resolve(cp_ref);

           if (pvcp == NULL) {

             // this entry has been GC'ed so remove it

             delete pv_node;

             ik->previous_versions()->remove_at(i);

             // Since we are traversing the array backwards, we don't have to

             // do anything special with the index.

             gc_count++;

             continue;

           } else {

             RC_TRACE(0x00000200, ("unload: previous version @%d is alive", i));

             if (is_alive->do_object_b(pvcp)) {

               live_count++;

             } else {

               guarantee(false, "sanity check");

             }

           }

           GrowableArray<jweak>* method_refs = pv_node->prev_EMCP_methods();

           if (method_refs != NULL) {

             RC_TRACE(0x00000200, ("unload: previous methods length=%d",

               method_refs->length()));

             for (int j = method_refs->length() - 1; j >= 0; j--) {

               jweak method_ref = method_refs->at(j);

               assert(method_ref != NULL, "weak method ref was unexpectedly cleared");

               if (method_ref == NULL) {

                 method_refs->remove_at(j);

                 // Since we are traversing the array backwards, we don't have to

                 // do anything special with the index.

                 continue;  // robustness

               }

               methodOop method = (methodOop)JNIHandles::resolve(method_ref);

               if (method == NULL) {

                 // this method entry has been GC'ed so remove it

                 JNIHandles::destroy_weak_global(method_ref);

                 method_refs->remove_at(j);

               } else {

                 // RC_TRACE macro has an embedded ResourceMark

                 RC_TRACE(0x00000200,

                   ("unload: %s(%s): prev method @%d in version @%d is alive",

                   method->name()->as_C_string(),

                   method->signature()->as_C_string(), j, i));

               }

             }

           }

         }

         assert(ik->previous_versions()->length() == live_count, "sanity check");

         RC_TRACE(0x00000200,

           ("unload: previous version stats: live=%d, GC'ed=%d", live_count,

           gc_count));

       }

       // Non-unloadable classes were handled in always_strong_oops_do

       if (!is_strongly_reachable(class_loader, e)) {

         // Entry was not visited in phase1 (negated test from phase1)

         assert(class_loader != NULL, "unloading entry with null class loader");

         oop k_def_class_loader = ik->class_loader();

         // Do we need to delete this system dictionary entry?

         bool purge_entry = false;

         // Do we need to delete this system dictionary entry?

         if (!is_alive->do_object_b(class_loader)) {

           // 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 == class_loader) {

             // This is the defining entry, so the referred class is about

             // to be unloaded.

             // Notify the debugger and clean up the class.

             guarantee(!is_alive->do_object_b(e),

                       "klass should not be live if defining loader is not");

             class_was_unloaded = true;

             // notify the debugger

             if (JvmtiExport::should_post_class_unload()) {

               JvmtiExport::post_class_unload(ik->as_klassOop());

             }

             // notify ClassLoadingService of class unload

             ClassLoadingService::notify_class_unloaded(ik);

             // Clean up C heap

             ik->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,

           // the loader must be an initiating loader (rather than the

           // defining loader). Remove this entry.

           if (!is_alive->do_object_b(e)) {

             guarantee(!is_alive->do_object_b(k_def_class_loader),

                       "defining loader should not be live if klass is not");

             // If we get here, the class_loader must not be the defining

             // loader, it must be an initiating one.

             assert(k_def_class_loader != class_loader,

                    "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_classes_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()) {

       klassOop e = probe->klass();

       oop class_loader = probe->loader();

       if (is_strongly_reachable(class_loader, e)) {

         blk->do_oop((oop*)probe->klass_addr());

         if (class_loader != NULL) {

           blk->do_oop(probe->loader_addr());

         }

         probe->protection_domain_set_oops_do(blk);

       }

     }

   }

 }

 //   Just the classes from defining class loaders

 void Dictionary::classes_do(void f(klassOop)) {

   for (int index = 0; index < table_size(); index++) {

     for (DictionaryEntry* probe = bucket(index);

                           probe != NULL;

                           probe = probe->next()) {

       klassOop k = probe->klass();

       if (probe->loader() == instanceKlass::cast(k)->class_loader()) {

         f(k);

       }

     }

   }

 }

 // Added for initialize_itable_for_klass to handle exceptions

 //   Just the classes from defining class loaders

 void Dictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {

   for (int index = 0; index < table_size(); index++) {

     for (DictionaryEntry* probe = bucket(index);

                           probe != NULL;

                           probe = probe->next()) {

       klassOop k = probe->klass();

       if (probe->loader() == instanceKlass::cast(k)->class_loader()) {

         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(klassOop, oop, TRAPS), TRAPS) {

   for (int index = 0; index < table_size(); index++) {

     for (DictionaryEntry* probe = bucket(index);

                           probe != NULL;

                           probe = probe->next()) {

       klassOop k = probe->klass();

       f(k, probe->loader(), CHECK);

     }

   }

 }

 //   All classes, and their class loaders

 // Don't iterate over placeholders

 void Dictionary::classes_do(void f(klassOop, oop)) {

   for (int index = 0; index < table_size(); index++) {

     for (DictionaryEntry* probe = bucket(index);

                           probe != NULL;

                           probe = probe->next()) {

       klassOop k = probe->klass();

       f(k, probe->loader());

     }

   }

 }

 void Dictionary::oops_do(OopClosure* f) {

   for (int index = 0; index < table_size(); index++) {

     for (DictionaryEntry* probe = bucket(index);

                           probe != NULL;

                           probe = probe->next()) {

       f->do_oop((oop*)probe->klass_addr());

       if (probe->loader() != NULL) {

         f->do_oop(probe->loader_addr());

       }

       probe->protection_domain_set_oops_do(f);

     }

   }

 }

 void Dictionary::methods_do(void f(methodOop)) {

   for (int index = 0; index < table_size(); index++) {

     for (DictionaryEntry* probe = bucket(index);

                           probe != NULL;

                           probe = probe->next()) {

       klassOop k = probe->klass();

       if (probe->loader() == instanceKlass::cast(k)->class_loader()) {

         // only take klass is we have the entry with the defining class loader

         instanceKlass::cast(k)->methods_do(f);

       }

     }

   }

 }

 klassOop Dictionary::try_get_next_class() {

   while (true) {

     if (_current_class_entry != NULL) {

       klassOop 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, Handle class_loader,

                            KlassHandle obj) {

   assert_locked_or_safepoint(SystemDictionary_lock);

   assert(obj() != NULL, "adding NULL obj");

   assert(Klass::cast(obj())->name() == class_name, "sanity check on name");

   unsigned int hash = compute_hash(class_name, class_loader);

   int index = hash_to_index(hash);

   DictionaryEntry* entry = new_entry(hash, obj(), class_loader());

   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,

                                        Handle class_loader) {

   oop loader = class_loader();

   debug_only(_lookup_count++);

   for (DictionaryEntry* entry = bucket(index);

                         entry != NULL;

                         entry = entry->next()) {

     if (entry->hash() == hash && entry->equals(class_name, loader)) {

       return entry;

     }

     debug_only(_lookup_length++);

   }

   return NULL;

 }

 klassOop Dictionary::find(int index, unsigned int hash, Symbol* name,

                           Handle loader, Handle protection_domain, TRAPS) {

   DictionaryEntry* entry = get_entry(index, hash, name, loader);

   if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {

     return entry->klass();

   } else {

     return NULL;

   }

 }

 klassOop Dictionary::find_class(int index, unsigned int hash,

                                 Symbol* name, Handle loader) {

   assert_locked_or_safepoint(SystemDictionary_lock);

   assert (index == index_for(name, loader), "incorrect index?");

   DictionaryEntry* entry = get_entry(index, hash, name, loader);

   return (entry != NULL) ? entry->klass() : (klassOop)NULL;

 }

 // Variant of find_class for shared classes.  No locking required, as

 // that table is static.

 klassOop Dictionary::find_shared_class(int index, unsigned int hash,

                                        Symbol* name) {

   assert (index == index_for(name, Handle()), "incorrect index?");

   DictionaryEntry* entry = get_entry(index, hash, name, Handle());

   return (entry != NULL) ? entry->klass() : (klassOop)NULL;

 }

 void Dictionary::add_protection_domain(int index, unsigned int hash,

                                        instanceKlassHandle klass,

                                        Handle loader, Handle protection_domain,

                                        TRAPS) {

   Symbol*  klass_name = klass->name();

   DictionaryEntry* entry = get_entry(index, hash, klass_name, loader);

   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,

                                             Handle loader,

                                             Handle protection_domain) {

   DictionaryEntry* entry = get_entry(index, hash, name, loader);

   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.

   Thread *thread = Thread::current();

   while (master_list != NULL) {

     DictionaryEntry* p = master_list;

     master_list = master_list->next();

     p->set_next(NULL);

     Symbol* class_name = instanceKlass::cast((klassOop)(p->klass()))->name();

     unsigned int hash = compute_hash(class_name, Handle(thread, p->loader()));

     int index = hash_to_index(hash);

     p->set_hash(hash);

     p->set_next(bucket(index));

     set_entry(index, p);

   }

 }

 SymbolPropertyTable::SymbolPropertyTable(int table_size)

   : Hashtable<Symbol*>(table_size, sizeof(SymbolPropertyEntry))

 {

 }

 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket* t,

                                          int number_of_entries)

   : Hashtable<Symbol*>(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*>::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->property_oop() != NULL) {

         f->do_oop(p->property_oop_addr());

       }

     }

   }

 }

 void SymbolPropertyTable::methods_do(void f(methodOop)) {

   for (int index = 0; index < table_size(); index++) {

     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {

       oop prop = p->property_oop();

       if (prop != NULL && prop->is_method()) {

         f((methodOop)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);

       klassOop e = probe->klass();

       oop class_loader =  probe->loader();

       bool is_defining_class =

          (class_loader == instanceKlass::cast(e)->class_loader());

       tty->print("%s%s", is_defining_class ? " " : "^",

                    Klass::cast(e)->external_name());

       if (class_loader != NULL) {

         tty->print(", loader ");

         class_loader->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()) {

       klassOop e = probe->klass();

       oop class_loader = probe->loader();

       guarantee(Klass::cast(e)->oop_is_instance(),

                               "Verify of system dictionary failed");

       // class loader must be present;  a null class loader is the

       // boostrap loader

       guarantee(class_loader == NULL || 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()));

 }