Java example source code file (Universe.java)

This example Java source code file (Universe.java) 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

addressfield, cintegerfield, collectedheap, g1collectedheap, gencollectedheap, object, observer, oop, parallelscavengeheap, type, universe, util, virtualconstructor, wrongtypeexception

The Universe.java Java example source code

/*
 * Copyright (c) 2000, 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.
 *
 */

package sun.jvm.hotspot.memory;

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.gc_interface.*;
import sun.jvm.hotspot.gc_implementation.g1.G1CollectedHeap;
import sun.jvm.hotspot.gc_implementation.parallelScavenge.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.types.*;
import sun.jvm.hotspot.runtime.*;


public class Universe {
  private static AddressField collectedHeapField;
  private static VirtualConstructor heapConstructor;
  private static sun.jvm.hotspot.types.OopField mainThreadGroupField;
  private static sun.jvm.hotspot.types.OopField systemThreadGroupField;

  // single dimensional primitive array klasses
  private static sun.jvm.hotspot.types.AddressField boolArrayKlassField;
  private static sun.jvm.hotspot.types.AddressField byteArrayKlassField;
  private static sun.jvm.hotspot.types.AddressField charArrayKlassField;
  private static sun.jvm.hotspot.types.AddressField intArrayKlassField;
  private static sun.jvm.hotspot.types.AddressField shortArrayKlassField;
  private static sun.jvm.hotspot.types.AddressField longArrayKlassField;
  private static sun.jvm.hotspot.types.AddressField singleArrayKlassField;
  private static sun.jvm.hotspot.types.AddressField doubleArrayKlassField;

  private static AddressField narrowOopBaseField;
  private static CIntegerField narrowOopShiftField;
  private static AddressField narrowKlassBaseField;
  private static CIntegerField narrowKlassShiftField;

  static {
    VM.registerVMInitializedObserver(new Observer() {
        public void update(Observable o, Object data) {
          initialize(VM.getVM().getTypeDataBase());
        }
      });
  }

  private static synchronized void initialize(TypeDataBase db) {
    Type type = db.lookupType("Universe");

    collectedHeapField = type.getAddressField("_collectedHeap");

    heapConstructor = new VirtualConstructor(db);
    heapConstructor.addMapping("GenCollectedHeap", GenCollectedHeap.class);
    heapConstructor.addMapping("ParallelScavengeHeap", ParallelScavengeHeap.class);
    heapConstructor.addMapping("G1CollectedHeap", G1CollectedHeap.class);

    mainThreadGroupField   = type.getOopField("_main_thread_group");
    systemThreadGroupField = type.getOopField("_system_thread_group");

    boolArrayKlassField      = type.getAddressField("_boolArrayKlassObj");
    byteArrayKlassField      = type.getAddressField("_byteArrayKlassObj");
    charArrayKlassField      = type.getAddressField("_charArrayKlassObj");
    intArrayKlassField       = type.getAddressField("_intArrayKlassObj");
    shortArrayKlassField     = type.getAddressField("_shortArrayKlassObj");
    longArrayKlassField      = type.getAddressField("_longArrayKlassObj");
    singleArrayKlassField    = type.getAddressField("_singleArrayKlassObj");
    doubleArrayKlassField    = type.getAddressField("_doubleArrayKlassObj");

    narrowOopBaseField = type.getAddressField("_narrow_oop._base");
    narrowOopShiftField = type.getCIntegerField("_narrow_oop._shift");
    narrowKlassBaseField = type.getAddressField("_narrow_klass._base");
    narrowKlassShiftField = type.getCIntegerField("_narrow_klass._shift");
  }

  public Universe() {
  }

  public CollectedHeap heap() {
    try {
      return (CollectedHeap) heapConstructor.instantiateWrapperFor(collectedHeapField.getValue());
    } catch (WrongTypeException e) {
      return new CollectedHeap(collectedHeapField.getValue());
    }
  }

  public static long getNarrowOopBase() {
    if (narrowOopBaseField.getValue() == null) {
      return 0;
    } else {
      return narrowOopBaseField.getValue().minus(null);
    }
  }

  public static int getNarrowOopShift() {
    return (int)narrowOopShiftField.getValue();
  }

  public static long getNarrowKlassBase() {
    if (narrowKlassBaseField.getValue() == null) {
      return 0;
    } else {
      return narrowKlassBaseField.getValue().minus(null);
    }
  }

  public static int getNarrowKlassShift() {
    return (int)narrowKlassShiftField.getValue();
  }


  /** Returns "TRUE" iff "p" points into the allocated area of the heap. */
  public boolean isIn(Address p) {
    return heap().isIn(p);
  }

  /** Returns "TRUE" iff "p" points into the reserved area of the heap. */
  public boolean isInReserved(Address p) {
    return heap().isInReserved(p);
  }

  private Oop newOop(OopHandle handle) {
    return VM.getVM().getObjectHeap().newOop(handle);
  }

  public Oop mainThreadGroup() {
    return newOop(mainThreadGroupField.getValue());
  }

  public Oop systemThreadGroup() {
    return newOop(systemThreadGroupField.getValue());
  }

  // iterate through the single dimensional primitive array klasses
  // refer to basic_type_classes_do(void f(Klass*)) in universe.cpp
  public void basicTypeClassesDo(SystemDictionary.ClassVisitor visitor) {
    visitor.visit(new TypeArrayKlass(boolArrayKlassField.getValue()));
    visitor.visit(new TypeArrayKlass(byteArrayKlassField.getValue()));
    visitor.visit(new TypeArrayKlass(charArrayKlassField.getValue()));
    visitor.visit(new TypeArrayKlass(intArrayKlassField.getValue()));
    visitor.visit(new TypeArrayKlass(shortArrayKlassField.getValue()));
    visitor.visit(new TypeArrayKlass(longArrayKlassField.getValue()));
    visitor.visit(new TypeArrayKlass(singleArrayKlassField.getValue()));
    visitor.visit(new TypeArrayKlass(doubleArrayKlassField.getValue()));
  }

  public void print() { printOn(System.out); }
  public void printOn(PrintStream tty) {
    heap().printOn(tty);
  }

  // Check whether an element of a typeArrayOop with the given type must be
  // aligned 0 mod 8.  The typeArrayOop itself must be aligned at least this
  // strongly.
  public static boolean elementTypeShouldBeAligned(BasicType type) {
    return type == BasicType.T_DOUBLE || type == BasicType.T_LONG;
  }

  // Check whether an object field (static/non-static) of the given type must be
  // aligned 0 mod 8.
  public static boolean fieldTypeShouldBeAligned(BasicType type) {
    return type == BasicType.T_DOUBLE || type == BasicType.T_LONG;
  }
}