view src/share/vm/oops/objArrayKlassKlass.cpp @ 3917:eca1193ca245

4965777: GC changes to support use of discovered field for pending references Summary: If and when the reference handler thread is able to use the discovered field to link reference objects in its pending list, so will GC. In that case, GC will scan through this field once a reference object has been placed on the pending list, but not scan that field before that stage, as the field is used by the concurrent GC thread to link discovered objects. When ReferenceHandleR thread does not use the discovered field for the purpose of linking the elements in the pending list, as would be the case in older JDKs, the JVM will fall back to the old behaviour of using the next field for that purpose. Reviewed-by: jcoomes, mchung, stefank
author ysr
date Wed, 07 Sep 2011 13:55:42 -0700
parents c7f3d0b4570f
children fc9d8850ab8b
line wrap: on
line source

/*
 * Copyright (c) 1997, 2011, 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/javaClasses.hpp"
#include "classfile/systemDictionary.hpp"
#include "gc_implementation/shared/markSweep.inline.hpp"
#include "gc_interface/collectedHeap.inline.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/objArrayKlassKlass.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oop.inline2.hpp"
#ifndef SERIALGC
#include "gc_implementation/parNew/parOopClosures.inline.hpp"
#include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
#include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
#include "memory/cardTableRS.hpp"
#include "oops/oop.pcgc.inline.hpp"
#endif

klassOop objArrayKlassKlass::create_klass(TRAPS) {
  objArrayKlassKlass o;
  KlassHandle h_this_klass(THREAD, Universe::klassKlassObj());
  KlassHandle k = base_create_klass(h_this_klass, header_size(), o.vtbl_value(), CHECK_0);
  assert(k()->size() == align_object_size(header_size()), "wrong size for object");
  java_lang_Class::create_mirror(k, CHECK_0); // Allocate mirror
  return k();
}

klassOop objArrayKlassKlass::allocate_system_objArray_klass(TRAPS) {
  // system_objArrays have no instance klass, so allocate with fake class, then reset to NULL
  KlassHandle kk(THREAD, Universe::intArrayKlassObj());
  klassOop k = allocate_objArray_klass(1, kk, CHECK_0);
  objArrayKlass* tk = (objArrayKlass*) k->klass_part();
  tk->set_element_klass(NULL);
  tk->set_bottom_klass(NULL);
  return k;
}


klassOop objArrayKlassKlass::allocate_objArray_klass(int n, KlassHandle element_klass, TRAPS) {
  objArrayKlassKlassHandle this_oop(THREAD, as_klassOop());
  return allocate_objArray_klass_impl(this_oop, n, element_klass, THREAD);
}

klassOop objArrayKlassKlass::allocate_objArray_klass_impl(objArrayKlassKlassHandle this_oop,
                                                          int n, KlassHandle element_klass, TRAPS) {

  // Eagerly allocate the direct array supertype.
  KlassHandle super_klass = KlassHandle();
  if (!Universe::is_bootstrapping()) {
    KlassHandle element_super (THREAD, element_klass->super());
    if (element_super.not_null()) {
      // The element type has a direct super.  E.g., String[] has direct super of Object[].
      super_klass = KlassHandle(THREAD, element_super->array_klass_or_null());
      bool supers_exist = super_klass.not_null();
      // Also, see if the element has secondary supertypes.
      // We need an array type for each.
      objArrayHandle element_supers = objArrayHandle(THREAD,
                                            element_klass->secondary_supers());
      for( int i = element_supers->length()-1; i >= 0; i-- ) {
        klassOop elem_super = (klassOop) element_supers->obj_at(i);
        if (Klass::cast(elem_super)->array_klass_or_null() == NULL) {
          supers_exist = false;
          break;
        }
      }
      if (!supers_exist) {
        // Oops.  Not allocated yet.  Back out, allocate it, and retry.
#ifndef PRODUCT
        if (WizardMode) {
          tty->print_cr("Must retry array klass creation for depth %d",n);
        }
#endif
        KlassHandle ek;
        {
          MutexUnlocker mu(MultiArray_lock);
          MutexUnlocker mc(Compile_lock);   // for vtables
          klassOop sk = element_super->array_klass(CHECK_0);
          super_klass = KlassHandle(THREAD, sk);
          for( int i = element_supers->length()-1; i >= 0; i-- ) {
            KlassHandle elem_super (THREAD, element_supers->obj_at(i));
            elem_super->array_klass(CHECK_0);
          }
          // Now retry from the beginning
          klassOop klass_oop = element_klass->array_klass(n, CHECK_0);
          // Create a handle because the enclosing brace, when locking
          // can cause a gc.  Better to have this function return a Handle.
          ek = KlassHandle(THREAD, klass_oop);
        }  // re-lock
        return ek();
      }
    } else {
      // The element type is already Object.  Object[] has direct super of Object.
      super_klass = KlassHandle(THREAD, SystemDictionary::Object_klass());
    }
  }

  // Create type name for klass.
  Symbol* name = NULL;
  if (!element_klass->oop_is_instance() ||
      (name = instanceKlass::cast(element_klass())->array_name()) == NULL) {

    ResourceMark rm(THREAD);
    char *name_str = element_klass->name()->as_C_string();
    int len = element_klass->name()->utf8_length();
    char *new_str = NEW_RESOURCE_ARRAY(char, len + 4);
    int idx = 0;
    new_str[idx++] = '[';
    if (element_klass->oop_is_instance()) { // it could be an array or simple type
      new_str[idx++] = 'L';
    }
    memcpy(&new_str[idx], name_str, len * sizeof(char));
    idx += len;
    if (element_klass->oop_is_instance()) {
      new_str[idx++] = ';';
    }
    new_str[idx++] = '\0';
    name = SymbolTable::new_symbol(new_str, CHECK_0);
    if (element_klass->oop_is_instance()) {
      instanceKlass* ik = instanceKlass::cast(element_klass());
      ik->set_array_name(name);
    }
  }

  objArrayKlass o;
  arrayKlassHandle k = arrayKlass::base_create_array_klass(o.vtbl_value(),
                                                           objArrayKlass::header_size(),
                                                          this_oop,
                                                           CHECK_0);

  // Initialize instance variables
  objArrayKlass* oak = objArrayKlass::cast(k());
  oak->set_dimension(n);
  oak->set_element_klass(element_klass());
  oak->set_name(name);
  // decrement refcount because object arrays are not explicitly freed.  The
  // instanceKlass array_name() keeps the name counted while the klass is
  // loaded.
  name->decrement_refcount();

  klassOop bk;
  if (element_klass->oop_is_objArray()) {
    bk = objArrayKlass::cast(element_klass())->bottom_klass();
  } else {
    bk = element_klass();
  }
  assert(bk != NULL && (Klass::cast(bk)->oop_is_instance() || Klass::cast(bk)->oop_is_typeArray()), "invalid bottom klass");
  oak->set_bottom_klass(bk);

  oak->set_layout_helper(array_layout_helper(T_OBJECT));
  assert(oak->oop_is_javaArray(), "sanity");
  assert(oak->oop_is_objArray(), "sanity");

  // Call complete_create_array_klass after all instance variables has been initialized.
  arrayKlass::complete_create_array_klass(k, super_klass, CHECK_0);

  return k();
}


void objArrayKlassKlass::oop_follow_contents(oop obj) {
  assert(obj->is_klass(), "must be klass");
  assert(klassOop(obj)->klass_part()->oop_is_objArray_slow(), "must be obj array");

  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  MarkSweep::mark_and_push(oak->element_klass_addr());
  MarkSweep::mark_and_push(oak->bottom_klass_addr());

  arrayKlassKlass::oop_follow_contents(obj);
}

#ifndef SERIALGC
void objArrayKlassKlass::oop_follow_contents(ParCompactionManager* cm,
                                             oop obj) {
  assert(obj->is_klass(), "must be klass");
  assert(klassOop(obj)->klass_part()->oop_is_objArray_slow(), "must be obj array");

  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  PSParallelCompact::mark_and_push(cm, oak->element_klass_addr());
  PSParallelCompact::mark_and_push(cm, oak->bottom_klass_addr());

  arrayKlassKlass::oop_follow_contents(cm, obj);
}
#endif // SERIALGC


int objArrayKlassKlass::oop_adjust_pointers(oop obj) {
  assert(obj->is_klass(), "must be klass");
  assert(klassOop(obj)->klass_part()->oop_is_objArray_slow(), "must be obj array");

  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  MarkSweep::adjust_pointer(oak->element_klass_addr());
  MarkSweep::adjust_pointer(oak->bottom_klass_addr());

  return arrayKlassKlass::oop_adjust_pointers(obj);
}



int objArrayKlassKlass::oop_oop_iterate(oop obj, OopClosure* blk) {
  assert(obj->is_klass(), "must be klass");
  assert(klassOop(obj)->klass_part()->oop_is_objArray_slow(), "must be obj array");

  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  blk->do_oop(oak->element_klass_addr());
  blk->do_oop(oak->bottom_klass_addr());

  return arrayKlassKlass::oop_oop_iterate(obj, blk);
}


int
objArrayKlassKlass::oop_oop_iterate_m(oop obj, OopClosure* blk, MemRegion mr) {
  assert(obj->is_klass(), "must be klass");
  assert(klassOop(obj)->klass_part()->oop_is_objArray_slow(), "must be obj array");

  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  oop* addr;
  addr = oak->element_klass_addr();
  if (mr.contains(addr)) blk->do_oop(addr);
  addr = oak->bottom_klass_addr();
  if (mr.contains(addr)) blk->do_oop(addr);

  return arrayKlassKlass::oop_oop_iterate_m(obj, blk, mr);
}

#ifndef SERIALGC
void objArrayKlassKlass::oop_push_contents(PSPromotionManager* pm, oop obj) {
  assert(obj->blueprint()->oop_is_objArrayKlass(),"must be an obj array klass");
  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  oop* p = oak->element_klass_addr();
  if (PSScavenge::should_scavenge(p)) {
    pm->claim_or_forward_depth(p);
  }
  p = oak->bottom_klass_addr();
  if (PSScavenge::should_scavenge(p)) {
    pm->claim_or_forward_depth(p);
  }

  arrayKlassKlass::oop_push_contents(pm, obj);
}

int objArrayKlassKlass::oop_update_pointers(ParCompactionManager* cm, oop obj) {
  assert(obj->is_klass(), "must be klass");
  assert(klassOop(obj)->klass_part()->oop_is_objArray_slow(), "must be obj array");

  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  PSParallelCompact::adjust_pointer(oak->element_klass_addr());
  PSParallelCompact::adjust_pointer(oak->bottom_klass_addr());

  return arrayKlassKlass::oop_update_pointers(cm, obj);
}
#endif // SERIALGC

#ifndef PRODUCT

// Printing

void objArrayKlassKlass::oop_print_on(oop obj, outputStream* st) {
  assert(obj->is_klass(), "must be klass");
  objArrayKlass* oak = (objArrayKlass*) klassOop(obj)->klass_part();
  klassKlass::oop_print_on(obj, st);
  st->print(" - instance klass: ");
  oak->element_klass()->print_value_on(st);
  st->cr();
}

#endif //PRODUCT

void objArrayKlassKlass::oop_print_value_on(oop obj, outputStream* st) {
  assert(obj->is_klass(), "must be klass");
  objArrayKlass* oak = (objArrayKlass*) klassOop(obj)->klass_part();

  oak->element_klass()->print_value_on(st);
  st->print("[]");
}

const char* objArrayKlassKlass::internal_name() const {
  return "{object array class}";
}


// Verification

void objArrayKlassKlass::oop_verify_on(oop obj, outputStream* st) {
  arrayKlassKlass::oop_verify_on(obj, st);
  objArrayKlass* oak = objArrayKlass::cast((klassOop)obj);
  guarantee(oak->element_klass()->is_perm(),  "should be in permspace");
  guarantee(oak->element_klass()->is_klass(), "should be klass");
  guarantee(oak->bottom_klass()->is_perm(),   "should be in permspace");
  guarantee(oak->bottom_klass()->is_klass(),  "should be klass");
  Klass* bk = Klass::cast(oak->bottom_klass());
  guarantee(bk->oop_is_instance() || bk->oop_is_typeArray(),  "invalid bottom klass");
}