Java example source code file (arrayKlass.cpp)

This example Java source code file (arrayKlass.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arrayklass\:\:array_klasses_do, arrayklass\:\:cast, arrayklass\:\:compute_secondary_supers, check, check_0, instanceklass\:\:header_size, jvm_acc_abstract, klass, klasshandle, null, systemdictionary\:\:object_klass, throw_0, traps, universe\:\:base_vtable_size

The arrayKlass.cpp Java example source code

/*
 * Copyright (c) 1997, 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/javaClasses.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc_interface/collectedHeap.inline.hpp"
#include "jvmtifiles/jvmti.h"
#include "memory/gcLocker.hpp"
#include "memory/universe.inline.hpp"
#include "oops/arrayKlass.hpp"
#include "oops/arrayOop.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/objArrayOop.hpp"
#include "oops/oop.inline.hpp"

int ArrayKlass::static_size(int header_size) {
  // size of an array klass object
  assert(header_size <= InstanceKlass::header_size(), "bad header size");
  // If this assert fails, see comments in base_create_array_klass.
  header_size = InstanceKlass::header_size();
  int vtable_len = Universe::base_vtable_size();
#ifdef _LP64
  int size = header_size + align_object_offset(vtable_len);
#else
  int size = header_size + vtable_len;
#endif
  return align_object_size(size);
}


Klass* ArrayKlass::java_super() const {
  if (super() == NULL)  return NULL;  // bootstrap case
  // Array klasses have primary supertypes which are not reported to Java.
  // Example super chain:  String[][] -> Object[][] -> Object[] -> Object
  return SystemDictionary::Object_klass();
}


oop ArrayKlass::multi_allocate(int rank, jint* sizes, TRAPS) {
  ShouldNotReachHere();
  return NULL;
}

Method* ArrayKlass::uncached_lookup_method(Symbol* name, Symbol* signature) const {
  // There are no methods in an array klass but the super class (Object) has some
  assert(super(), "super klass must be present");
  return super()->uncached_lookup_method(name, signature);
}

ArrayKlass::ArrayKlass(Symbol* name) {
  set_name(name);

  set_super(Universe::is_bootstrapping() ? (Klass*)NULL : SystemDictionary::Object_klass());
  set_layout_helper(Klass::_lh_neutral_value);
  set_dimension(1);
  set_higher_dimension(NULL);
  set_lower_dimension(NULL);
  set_component_mirror(NULL);
  // Arrays don't add any new methods, so their vtable is the same size as
  // the vtable of klass Object.
  int vtable_size = Universe::base_vtable_size();
  set_vtable_length(vtable_size);
  set_is_cloneable(); // All arrays are considered to be cloneable (See JLS 20.1.5)
}


// Initialization of vtables and mirror object is done separatly from base_create_array_klass,
// since a GC can happen. At this point all instance variables of the ArrayKlass must be setup.
void ArrayKlass::complete_create_array_klass(ArrayKlass* k, KlassHandle super_klass, TRAPS) {
  ResourceMark rm(THREAD);
  k->initialize_supers(super_klass(), CHECK);
  k->vtable()->initialize_vtable(false, CHECK);
  java_lang_Class::create_mirror(k, Handle(NULL), CHECK);
}

GrowableArray<Klass*>* ArrayKlass::compute_secondary_supers(int num_extra_slots) {
  // interfaces = { cloneable_klass, serializable_klass };
  assert(num_extra_slots == 0, "sanity of primitive array type");
  // Must share this for correct bootstrapping!
  set_secondary_supers(Universe::the_array_interfaces_array());
  return NULL;
}

bool ArrayKlass::compute_is_subtype_of(Klass* k) {
  // An array is a subtype of Serializable, Clonable, and Object
  return    k == SystemDictionary::Object_klass()
         || k == SystemDictionary::Cloneable_klass()
         || k == SystemDictionary::Serializable_klass();
}


inline intptr_t* ArrayKlass::start_of_vtable() const {
  // all vtables start at the same place, that's why we use InstanceKlass::header_size here
  return ((intptr_t*)this) + InstanceKlass::header_size();
}


klassVtable* ArrayKlass::vtable() const {
  KlassHandle kh(Thread::current(), this);
  return new klassVtable(kh, start_of_vtable(), vtable_length() / vtableEntry::size());
}


objArrayOop ArrayKlass::allocate_arrayArray(int n, int length, TRAPS) {
  if (length < 0) {
    THROW_0(vmSymbols::java_lang_NegativeArraySizeException());
  }
  if (length > arrayOopDesc::max_array_length(T_ARRAY)) {
    report_java_out_of_memory("Requested array size exceeds VM limit");
    JvmtiExport::post_array_size_exhausted();
    THROW_OOP_0(Universe::out_of_memory_error_array_size());
  }
  int size = objArrayOopDesc::object_size(length);
  Klass* k = array_klass(n+dimension(), CHECK_0);
  ArrayKlass* ak = ArrayKlass::cast(k);
  objArrayOop o =
    (objArrayOop)CollectedHeap::array_allocate(ak, size, length, CHECK_0);
  // initialization to NULL not necessary, area already cleared
  return o;
}

void ArrayKlass::array_klasses_do(void f(Klass* k, TRAPS), TRAPS) {
  Klass* k = this;
  // Iterate over this array klass and all higher dimensions
  while (k != NULL) {
    f(k, CHECK);
    k = ArrayKlass::cast(k)->higher_dimension();
  }
}

void ArrayKlass::array_klasses_do(void f(Klass* k)) {
  Klass* k = this;
  // Iterate over this array klass and all higher dimensions
  while (k != NULL) {
    f(k);
    k = ArrayKlass::cast(k)->higher_dimension();
  }
}

// GC support

void ArrayKlass::oops_do(OopClosure* cl) {
  Klass::oops_do(cl);

  cl->do_oop(adr_component_mirror());
}

// JVM support

jint ArrayKlass::compute_modifier_flags(TRAPS) const {
  return JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC;
}

// JVMTI support

jint ArrayKlass::jvmti_class_status() const {
  return JVMTI_CLASS_STATUS_ARRAY;
}

void ArrayKlass::remove_unshareable_info() {
  Klass::remove_unshareable_info();
  // Clear the java mirror
  set_component_mirror(NULL);
}

void ArrayKlass::restore_unshareable_info(TRAPS) {
  Klass::restore_unshareable_info(CHECK);
  // Klass recreates the component mirror also
}

// Printing

void ArrayKlass::print_on(outputStream* st) const {
  assert(is_klass(), "must be klass");
  Klass::print_on(st);
}

void ArrayKlass::print_value_on(outputStream* st) const {
  assert(is_klass(), "must be klass");
  for(int index = 0; index < dimension(); index++) {
    st->print("[]");
  }
}

void ArrayKlass::oop_print_on(oop obj, outputStream* st) {
  assert(obj->is_array(), "must be array");
  Klass::oop_print_on(obj, st);
  st->print_cr(" - length: %d", arrayOop(obj)->length());
}


// Verification

void ArrayKlass::verify_on(outputStream* st, bool check_dictionary) {
  Klass::verify_on(st, check_dictionary);

  if (component_mirror() != NULL) {
    guarantee(component_mirror()->klass() != NULL, "should have a class");
  }
}

void ArrayKlass::oop_verify_on(oop obj, outputStream* st) {
  guarantee(obj->is_array(), "must be array");
  arrayOop a = arrayOop(obj);
  guarantee(a->length() >= 0, "array with negative length?");
}