jdk8-mips64-public/hotspot: src/share/vm/classfile/placeholders.cpp@5a32d2a3cc1e (annotated)

src/share/vm/classfile/placeholders.cpp@5a32d2a3cc1e (annotated)

src/share/vm/classfile/placeholders.cpp

Mon, 20 Jan 2014 11:47:07 +0100

author: tschatzl
date: Mon, 20 Jan 2014 11:47:07 +0100
changeset 6229: 5a32d2a3cc1e
parent 4425: aefb345d3f5e
child 6876: 710a3c8b516e
permissions: -rw-r--r--

8027476: Improve performance of Stringtable unlink
8027455: Improve symbol table scan times during gc pauses
Summary: Parallelize string table and symbol table scan during remark and full GC. Some additional statistics output if the experimental flag G1TraceStringSymbolTableScrubbing is set.
Reviewed-by: mgerdin, coleenp, brutisso

 /*
  * Copyright (c) 2003, 2013, 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/placeholders.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/fieldType.hpp"
 #include "utilities/hashtable.inline.hpp"
 // Placeholder methods
 PlaceholderEntry* PlaceholderTable::new_entry(int hash, Symbol* name,
                                               ClassLoaderData* loader_data,
                                               bool havesupername,
                                               Symbol* supername) {
   PlaceholderEntry* entry = (PlaceholderEntry*)Hashtable<Symbol*, mtClass>::new_entry(hash, name);
   // Hashtable with Symbol* literal must increment and decrement refcount.
   name->increment_refcount();
   entry->set_loader_data(loader_data);
   entry->set_havesupername(havesupername);
   entry->set_supername(supername);
   entry->set_superThreadQ(NULL);
   entry->set_loadInstanceThreadQ(NULL);
   entry->set_defineThreadQ(NULL);
   entry->set_definer(NULL);
   entry->set_instance_klass(NULL);
   return entry;
 }
 void PlaceholderTable::free_entry(PlaceholderEntry* entry) {
   // decrement Symbol refcount here because Hashtable doesn't.
   entry->literal()->decrement_refcount();
   if (entry->supername() != NULL) entry->supername()->decrement_refcount();
   Hashtable<Symbol*, mtClass>::free_entry(entry);
 }
 // Placeholder objects represent classes currently being loaded.
 // All threads examining the placeholder table must hold the
 // SystemDictionary_lock, so we don't need special precautions
 // on store ordering here.
 void PlaceholderTable::add_entry(int index, unsigned int hash,
                                  Symbol* class_name, ClassLoaderData* loader_data,
                                  bool havesupername, Symbol* supername){
   assert_locked_or_safepoint(SystemDictionary_lock);
   assert(class_name != NULL, "adding NULL obj");
   // Both readers and writers are locked so it's safe to just
   // create the placeholder and insert it in the list without a membar.
   PlaceholderEntry* entry = new_entry(hash, class_name, loader_data, havesupername, supername);
   add_entry(index, entry);
 }
 // Remove a placeholder object.
 void PlaceholderTable::remove_entry(int index, unsigned int hash,
                                     Symbol* class_name,
                                     ClassLoaderData* loader_data) {
   assert_locked_or_safepoint(SystemDictionary_lock);
   PlaceholderEntry** p = bucket_addr(index);
   while (*p) {
     PlaceholderEntry *probe = *p;
     if (probe->hash() == hash && probe->equals(class_name, loader_data)) {
       // Delete entry
       *p = probe->next();
       free_entry(probe);
       return;
     }
     p = probe->next_addr();
   }
 }
 PlaceholderEntry* PlaceholderTable::get_entry(int index, unsigned int hash,
                                        Symbol* class_name,
                                        ClassLoaderData* loader_data) {
   assert_locked_or_safepoint(SystemDictionary_lock);
   for (PlaceholderEntry *place_probe = bucket(index);
                          place_probe != NULL;
                          place_probe = place_probe->next()) {
     if (place_probe->hash() == hash &&
         place_probe->equals(class_name, loader_data)) {
       return place_probe;
     }
   }
   return NULL;
 }
 Symbol* PlaceholderTable::find_entry(int index, unsigned int hash,
                                        Symbol* class_name,
                                        ClassLoaderData* loader_data) {
   PlaceholderEntry* probe = get_entry(index, hash, class_name, loader_data);
   return (probe? probe->klassname(): (Symbol*)NULL);
 }
   // find_and_add returns probe pointer - old or new
   // If no entry exists, add a placeholder entry
   // If entry exists, reuse entry
   // For both, push SeenThread for classloadAction
   // if havesupername: this is used for circularity for instanceklass loading
 PlaceholderEntry* PlaceholderTable::find_and_add(int index, unsigned int hash,
                                                  Symbol* name,
                                                  ClassLoaderData* loader_data,
                                                  classloadAction action,
                                                  Symbol* supername,
                                                  Thread* thread) {
   PlaceholderEntry* probe = get_entry(index, hash, name, loader_data);
   if (probe == NULL) {
     // Nothing found, add place holder
     add_entry(index, hash, name, loader_data, (action == LOAD_SUPER), supername);
     probe = get_entry(index, hash, name, loader_data);
   } else {
     if (action == LOAD_SUPER) {
       probe->set_havesupername(true);
       probe->set_supername(supername);
     }
   }
   if (probe) probe->add_seen_thread(thread, action);
   return probe;
 }
 // placeholder is used to track class loading internal states
 // placeholder existence now for loading superclass/superinterface
 // superthreadQ tracks class circularity, while loading superclass/superinterface
 // loadInstanceThreadQ tracks load_instance_class calls
 // definer() tracks the single thread that owns define token
 // defineThreadQ tracks waiters on defining thread's results
 // 1st claimant creates placeholder
 // find_and_add adds SeenThread entry for appropriate queue
 // All claimants remove SeenThread after completing action
 // On removal: if definer and all queues empty, remove entry
 // Note: you can be in both placeholders and systemDictionary
 // Therefore - must always check SD first
 // Ignores the case where entry is not found
 void PlaceholderTable::find_and_remove(int index, unsigned int hash,
                                        Symbol* name, ClassLoaderData* loader_data,
                                        classloadAction action,
                                        Thread* thread) {
     assert_locked_or_safepoint(SystemDictionary_lock);
     PlaceholderEntry *probe = get_entry(index, hash, name, loader_data);
     if (probe != NULL) {
        probe->remove_seen_thread(thread, action);
        // If no other threads using this entry, and this thread is not using this entry for other states
        if ((probe->superThreadQ() == NULL) && (probe->loadInstanceThreadQ() == NULL)
           && (probe->defineThreadQ() == NULL) && (probe->definer() == NULL)) {
          remove_entry(index, hash, name, loader_data);
        }
     }
   }
 PlaceholderTable::PlaceholderTable(int table_size)
     : TwoOopHashtable<Symbol*, mtClass>(table_size, sizeof(PlaceholderEntry)) {
 }
 void PlaceholderTable::classes_do(KlassClosure* f) {
   for (int index = 0; index < table_size(); index++) {
     for (PlaceholderEntry* probe = bucket(index);
                            probe != NULL;
                            probe = probe->next()) {
       probe->classes_do(f);
     }
   }
 }
 void PlaceholderEntry::classes_do(KlassClosure* closure) {
   assert(klassname() != NULL, "should have a non-null klass");
   if (_instanceKlass != NULL) {
     closure->do_klass(instance_klass());
   }
 }
 // do all entries in the placeholder table
 void PlaceholderTable::entries_do(void f(Symbol*)) {
   for (int index = 0; index < table_size(); index++) {
     for (PlaceholderEntry* probe = bucket(index);
                            probe != NULL;
                            probe = probe->next()) {
       f(probe->klassname());
     }
   }
 }
 #ifndef PRODUCT
 // Note, doesn't append a cr
 void PlaceholderEntry::print() const {
   klassname()->print_value();
   if (loader_data() != NULL) {
     tty->print(", loader ");
     loader_data()->print_value();
   }
   if (supername() != NULL) {
     tty->print(", supername ");
     supername()->print_value();
   }
   if (definer() != NULL) {
     tty->print(", definer ");
     definer()->print_value();
   }
   if (instance_klass() != NULL) {
     tty->print(", InstanceKlass ");
     instance_klass()->print_value();
   }
   tty->print("\n");
   tty->print("loadInstanceThreadQ threads:");
   loadInstanceThreadQ()->printActionQ();
   tty->print("\n");
   tty->print("superThreadQ threads:");
   superThreadQ()->printActionQ();
   tty->print("\n");
   tty->print("defineThreadQ threads:");
   defineThreadQ()->printActionQ();
   tty->print("\n");
 }
 #endif
 void PlaceholderEntry::verify() const {
   guarantee(loader_data() != NULL, "Must have been setup.");
   guarantee(loader_data()->class_loader() == NULL || loader_data()->class_loader()->is_instance(),
             "checking type of _loader");
   guarantee(instance_klass() == NULL
             || instance_klass()->oop_is_instance(),
             "checking type of instance_klass result");
 }
 void PlaceholderTable::verify() {
   int element_count = 0;
   for (int pindex = 0; pindex < table_size(); pindex++) {
     for (PlaceholderEntry* probe = bucket(pindex);
                            probe != NULL;
                            probe = probe->next()) {
       probe->verify();
       element_count++;  // both klasses and place holders count
     }
   }
   guarantee(number_of_entries() == element_count,
             "Verify of system dictionary failed");
 }
 #ifndef PRODUCT
 void PlaceholderTable::print() {
   for (int pindex = 0; pindex < table_size(); pindex++) {
     for (PlaceholderEntry* probe = bucket(pindex);
                            probe != NULL;
                            probe = probe->next()) {
       if (Verbose) tty->print("%4d: ", pindex);
       tty->print(" place holder ");
       probe->print();
       tty->cr();
     }
   }
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/classfile/placeholders.cpp@5a32d2a3cc1e (annotated)

src/share/vm/classfile/placeholders.cpp