JDK14/Java14源码在线阅读

/*
 * Copyright (c) 2001, 2018, 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.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.classfile.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.types.*;

public class SystemDictionary {
  private static sun.jvm.hotspot.types.OopField javaSystemLoaderField;

  private static AddressField objectKlassField;
  private static AddressField classLoaderKlassField;
  private static AddressField stringKlassField;
  private static AddressField systemKlassField;
  private static AddressField threadKlassField;
  private static AddressField threadGroupKlassField;
  private static AddressField methodHandleKlassField;

  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("SystemDictionary");

    javaSystemLoaderField = type.getOopField("_java_system_loader");

    objectKlassField = type.getAddressField(WK_KLASS("Object_klass"));
    classLoaderKlassField = type.getAddressField(WK_KLASS("ClassLoader_klass"));
    stringKlassField = type.getAddressField(WK_KLASS("String_klass"));
    systemKlassField = type.getAddressField(WK_KLASS("System_klass"));
    threadKlassField = type.getAddressField(WK_KLASS("Thread_klass"));
    threadGroupKlassField = type.getAddressField(WK_KLASS("ThreadGroup_klass"));
    methodHandleKlassField = type.getAddressField(WK_KLASS("MethodHandle_klass"));
  }

  // This WK functions must follow the definitions in systemDictionary.hpp:
  private static String WK_KLASS(String name) {
      //#define WK_KLASS(name) _well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]
      return ("_well_known_klasses[SystemDictionary::"+WK_KLASS_ENUM_NAME(name)+"]");
  }
  private static String WK_KLASS_ENUM_NAME(String kname) {
      //#define WK_KLASS_ENUM_NAME(kname)    kname##_knum
      return (kname+"_knum");
  }

  // few well known classes -- not all are added here.
  // add more if needed.
  public static InstanceKlass getThreadKlass() {
    return (InstanceKlass)Metadata.instantiateWrapperFor(threadKlassField.getValue());
  }

  public static InstanceKlass getThreadGroupKlass() {
    return (InstanceKlass)Metadata.instantiateWrapperFor(threadGroupKlassField.getValue());
  }

  public static InstanceKlass getObjectKlass() {
    return (InstanceKlass)Metadata.instantiateWrapperFor(objectKlassField.getValue());
  }

  public static InstanceKlass getStringKlass() {
    return (InstanceKlass)Metadata.instantiateWrapperFor(stringKlassField.getValue());
  }

  public static InstanceKlass getClassLoaderKlass() {
    return (InstanceKlass)Metadata.instantiateWrapperFor(classLoaderKlassField.getValue());
  }

  public static InstanceKlass getSystemKlass() {
    return (InstanceKlass)Metadata.instantiateWrapperFor(systemKlassField.getValue());
  }

  public static InstanceKlass getMethodHandleKlass() {

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