Java example source code file (ConstMethod.java)

This example Java source code file (ConstMethod.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

checkedexceptionelement, cintfield, compressedlinenumberreadstream, constmethod, exceptiontableelement, has_exception_table, has_generic_signature, has_localvariable_table, has_method_annotations, has_method_parameters, has_parameter_annotations, linenumbertableelement, localvariabletableelement, symbol, util

The ConstMethod.java Java example source code

/*
 * 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.
 *
 */

package sun.jvm.hotspot.oops;

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.code.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.interpreter.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.types.*;
import sun.jvm.hotspot.utilities.*;

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

  // anon-enum constants for _flags.
  private static int HAS_LINENUMBER_TABLE;
  private static int HAS_CHECKED_EXCEPTIONS;
  private static int HAS_LOCALVARIABLE_TABLE;
  private static int HAS_EXCEPTION_TABLE;
  private static int HAS_GENERIC_SIGNATURE;
  private static int HAS_METHOD_ANNOTATIONS;
  private static int HAS_PARAMETER_ANNOTATIONS;
  private static int HAS_METHOD_PARAMETERS;
  private static int HAS_DEFAULT_ANNOTATIONS;
  private static int HAS_TYPE_ANNOTATIONS;

  private static final int sizeofShort = 2;

  private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
    Type type                  = db.lookupType("ConstMethod");
    constants                  = new MetadataField(type.getAddressField("_constants"), 0);
    constMethodSize            = new CIntField(type.getCIntegerField("_constMethod_size"), 0);
    flags                      = new CIntField(type.getCIntegerField("_flags"), 0);

    // enum constants for flags
    HAS_LINENUMBER_TABLE      = db.lookupIntConstant("ConstMethod::_has_linenumber_table").intValue();
    HAS_CHECKED_EXCEPTIONS     = db.lookupIntConstant("ConstMethod::_has_checked_exceptions").intValue();
    HAS_LOCALVARIABLE_TABLE   = db.lookupIntConstant("ConstMethod::_has_localvariable_table").intValue();
    HAS_EXCEPTION_TABLE       = db.lookupIntConstant("ConstMethod::_has_exception_table").intValue();
    HAS_GENERIC_SIGNATURE     = db.lookupIntConstant("ConstMethod::_has_generic_signature").intValue();
    HAS_METHOD_ANNOTATIONS    = db.lookupIntConstant("ConstMethod::_has_method_annotations").intValue();
    HAS_PARAMETER_ANNOTATIONS = db.lookupIntConstant("ConstMethod::_has_parameter_annotations").intValue();
    HAS_METHOD_PARAMETERS = db.lookupIntConstant("ConstMethod::_has_method_parameters").intValue();
    HAS_DEFAULT_ANNOTATIONS   = db.lookupIntConstant("ConstMethod::_has_default_annotations").intValue();
    HAS_TYPE_ANNOTATIONS      = db.lookupIntConstant("ConstMethod::_has_type_annotations").intValue();

    // Size of Java bytecodes allocated immediately after ConstMethod*.
    codeSize                   = new CIntField(type.getCIntegerField("_code_size"), 0);
    nameIndex                  = new CIntField(type.getCIntegerField("_name_index"), 0);
    signatureIndex             = new CIntField(type.getCIntegerField("_signature_index"), 0);
    idnum                      = new CIntField(type.getCIntegerField("_method_idnum"), 0);
    maxStack                   = new CIntField(type.getCIntegerField("_max_stack"), 0);
    maxLocals                  = new CIntField(type.getCIntegerField("_max_locals"), 0);
    sizeOfParameters           = new CIntField(type.getCIntegerField("_size_of_parameters"), 0);

    // start of byte code
    bytecodeOffset = type.getSize();

    type                       = db.lookupType("MethodParametersElement");
    methodParametersElementSize = type.getSize();

    type                       = db.lookupType("CheckedExceptionElement");
    checkedExceptionElementSize = type.getSize();

    type                       = db.lookupType("LocalVariableTableElement");
    localVariableTableElementSize = type.getSize();

    type                       = db.lookupType("ExceptionTableElement");
    exceptionTableElementSize = type.getSize();
  }

  public ConstMethod(Address addr) {
    super(addr);
  }

  // Fields
  private static MetadataField constants;
  private static CIntField constMethodSize;
  private static CIntField flags;
  private static CIntField codeSize;
  private static CIntField nameIndex;
  private static CIntField signatureIndex;
  private static CIntField idnum;
  private static CIntField maxStack;
  private static CIntField maxLocals;
  private static CIntField sizeOfParameters;

  // start of bytecode
  private static long bytecodeOffset;
  private static long methodParametersElementSize;
  private static long checkedExceptionElementSize;
  private static long localVariableTableElementSize;
  private static long exceptionTableElementSize;

  public Method getMethod() {
    InstanceKlass ik = (InstanceKlass)getConstants().getPoolHolder();
    MethodArray methods = ik.getMethods();
    return methods.at((int)getIdNum());
  }

  // Accessors for declared fields
  public ConstantPool getConstants() {
    return (ConstantPool) constants.getValue(this);
  }

  public long getConstMethodSize() {
    return constMethodSize.getValue(this);
  }

  public long getFlags() {
    return flags.getValue(this);
  }

  public long getCodeSize() {
    return codeSize.getValue(this);
  }

  public long getNameIndex() {
    return nameIndex.getValue(this);
  }

  public long getSignatureIndex() {
    return signatureIndex.getValue(this);
  }

  public long getGenericSignatureIndex() {
    if (hasGenericSignature()) {
      return getAddress().getCIntegerAt(offsetOfGenericSignatureIndex(), 2, true);
    } else {
      return 0;
    }
  }

  public long getIdNum() {
    return idnum.getValue(this);
  }

  public long getMaxStack() {
    return maxStack.getValue(this);
  }

  public long getMaxLocals() {
    return maxLocals.getValue(this);
  }

  public long getSizeOfParameters() {
    return sizeOfParameters.getValue(this);
  }

  public Symbol getName() {
    return getMethod().getName();
  }

  public Symbol getSignature() {
    return getMethod().getSignature();
  }

  public Symbol getGenericSignature() {
    return getMethod().getGenericSignature();
  }

  // bytecode accessors

  /** Get a bytecode or breakpoint at the given bci */
  public int getBytecodeOrBPAt(int bci) {
    return getAddress().getJByteAt(bytecodeOffset + bci) & 0xFF;
  }

  public byte getBytecodeByteArg(int bci) {
    return (byte) getBytecodeOrBPAt(bci);
  }

  /** Fetches a 16-bit big-endian ("Java ordered") value from the
      bytecode stream */
  public short getBytecodeShortArg(int bci) {
    int hi = getBytecodeOrBPAt(bci);
    int lo = getBytecodeOrBPAt(bci + 1);
    return (short) ((hi << 8) | lo);
  }

  /** Fetches a 16-bit native ordered value from the
      bytecode stream */
  public short getNativeShortArg(int bci) {
    int hi = getBytecodeOrBPAt(bci);
    int lo = getBytecodeOrBPAt(bci + 1);
    if (VM.getVM().isBigEndian()) {
        return (short) ((hi << 8) | lo);
    } else {
        return (short) ((lo << 8) | hi);
    }
  }

  /** Fetches a 32-bit big-endian ("Java ordered") value from the
      bytecode stream */
  public int getBytecodeIntArg(int bci) {
    int b4 = getBytecodeOrBPAt(bci);
    int b3 = getBytecodeOrBPAt(bci + 1);
    int b2 = getBytecodeOrBPAt(bci + 2);
    int b1 = getBytecodeOrBPAt(bci + 3);

    return (b4 << 24) | (b3 << 16) | (b2 << 8) | b1;
  }

  /** Fetches a 32-bit native ordered value from the
      bytecode stream */
  public int getNativeIntArg(int bci) {
    int b4 = getBytecodeOrBPAt(bci);
    int b3 = getBytecodeOrBPAt(bci + 1);
    int b2 = getBytecodeOrBPAt(bci + 2);
    int b1 = getBytecodeOrBPAt(bci + 3);

    if (VM.getVM().isBigEndian()) {
        return (b4 << 24) | (b3 << 16) | (b2 << 8) | b1;
    } else {
        return (b1 << 24) | (b2 << 16) | (b3 << 8) | b4;
    }
  }

  public byte[] getByteCode() {
     byte[] bc = new byte[ (int) getCodeSize() ];
     for( int i=0; i < bc.length; i++ )
     {
        long offs = bytecodeOffset + i;
        bc[i] = getAddress().getJByteAt( offs );
     }
     return bc;
  }

  public long getSize() {
    return getConstMethodSize();
  }

  public void printValueOn(PrintStream tty) {
    tty.print("ConstMethod " + getName().asString() + getSignature().asString() + "@" + getAddress());
  }

  public void iterateFields(MetadataVisitor visitor) {
    visitor.doMetadata(constants, true);
      visitor.doCInt(constMethodSize, true);
      visitor.doCInt(flags, true);
      visitor.doCInt(codeSize, true);
      visitor.doCInt(nameIndex, true);
      visitor.doCInt(signatureIndex, true);
      visitor.doCInt(codeSize, true);
      visitor.doCInt(maxStack, true);
      visitor.doCInt(maxLocals, true);
      visitor.doCInt(sizeOfParameters, true);
    }

  // Accessors

  public boolean hasLineNumberTable() {
    return (getFlags() & HAS_LINENUMBER_TABLE) != 0;
  }

  public int getLineNumberFromBCI(int bci) {
    if (!VM.getVM().isCore()) {
      if (bci == DebugInformationRecorder.SYNCHRONIZATION_ENTRY_BCI) bci = 0;
    }

    if (isNative()) {
      return -1;
    }

    if (Assert.ASSERTS_ENABLED) {
      Assert.that(bci == 0 || 0 <= bci && bci < getCodeSize(), "illegal bci");
    }
    int bestBCI  =  0;
    int bestLine = -1;
    if (hasLineNumberTable()) {
      // The line numbers are a short array of 2-tuples [start_pc, line_number].
      // Not necessarily sorted and not necessarily one-to-one.
      CompressedLineNumberReadStream stream =
        new CompressedLineNumberReadStream(getAddress(), (int) offsetOfCompressedLineNumberTable());
      while (stream.readPair()) {
        if (stream.bci() == bci) {
          // perfect match
          return stream.line();
        } else {
          // update best_bci/line
          if (stream.bci() < bci && stream.bci() >= bestBCI) {
            bestBCI  = stream.bci();
            bestLine = stream.line();
          }
        }
      }
    }
    return bestLine;
  }

  public LineNumberTableElement[] getLineNumberTable() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(hasLineNumberTable(),
                  "should only be called if table is present");
    }
    int len = getLineNumberTableLength();
    CompressedLineNumberReadStream stream =
      new CompressedLineNumberReadStream(getAddress(), (int) offsetOfCompressedLineNumberTable());
    LineNumberTableElement[] ret = new LineNumberTableElement[len];

    for (int idx = 0; idx < len; idx++) {
      stream.readPair();
      ret[idx] = new LineNumberTableElement(stream.bci(), stream.line());
    }
    return ret;
  }

  public boolean hasLocalVariableTable() {
    return (getFlags() & HAS_LOCALVARIABLE_TABLE) != 0;
  }

  public Symbol getLocalVariableName(int bci, int slot) {
    return getMethod().getLocalVariableName(bci, slot);
  }

  /** Should only be called if table is present */
  public LocalVariableTableElement[] getLocalVariableTable() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(hasLocalVariableTable(), "should only be called if table is present");
    }
    LocalVariableTableElement[] ret = new LocalVariableTableElement[getLocalVariableTableLength()];
    long offset = offsetOfLocalVariableTable();
    for (int i = 0; i < ret.length; i++) {
      ret[i] = new LocalVariableTableElement(getAddress(), offset);
      offset += localVariableTableElementSize;
    }
    return ret;
  }

  public boolean hasExceptionTable() {
    return (getFlags() & HAS_EXCEPTION_TABLE) != 0;
  }

  public ExceptionTableElement[] getExceptionTable() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(hasExceptionTable(), "should only be called if table is present");
    }
    ExceptionTableElement[] ret = new ExceptionTableElement[getExceptionTableLength()];
    long offset = offsetOfExceptionTable();
    for (int i = 0; i < ret.length; i++) {
      ret[i] = new ExceptionTableElement(getAddress(), offset);
      offset += exceptionTableElementSize;
    }
    return ret;
  }

  public boolean hasCheckedExceptions() {
    return (getFlags() & HAS_CHECKED_EXCEPTIONS) != 0;
  }

  public CheckedExceptionElement[] getCheckedExceptions() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(hasCheckedExceptions(), "should only be called if table is present");
    }
    CheckedExceptionElement[] ret = new CheckedExceptionElement[getCheckedExceptionsLength()];
    long offset = offsetOfCheckedExceptions();
    for (int i = 0; i < ret.length; i++) {
      ret[i] = new CheckedExceptionElement(getAddress(), offset);
      offset += checkedExceptionElementSize;
    }
    return ret;
  }

  private boolean hasMethodParameters() {
    return (getFlags() & HAS_METHOD_PARAMETERS) != 0;
  }

  private boolean hasGenericSignature() {
    return (getFlags() & HAS_GENERIC_SIGNATURE) != 0;
  }

  private boolean hasMethodAnnotations() {
    return (getFlags() & HAS_METHOD_ANNOTATIONS) != 0;
  }

  private boolean hasParameterAnnotations() {
    return (getFlags() & HAS_PARAMETER_ANNOTATIONS) != 0;
  }

  private boolean hasDefaultAnnotations() {
    return (getFlags() & HAS_DEFAULT_ANNOTATIONS) != 0;
  }

  private boolean hasTypeAnnotations() {
    return (getFlags() & HAS_TYPE_ANNOTATIONS) != 0;
  }


  //---------------------------------------------------------------------------
  // Internals only below this point
  //

  private boolean isNative() {
    return getMethod().isNative();
  }

  // Offset of end of code
  private long offsetOfCodeEnd() {
    return bytecodeOffset + getCodeSize();
  }

  // Offset of start of compressed line number table (see method.hpp)
  private long offsetOfCompressedLineNumberTable() {
    return offsetOfCodeEnd() + (isNative() ? 2 * VM.getVM().getAddressSize() : 0);
  }

  // Offset of last short in Method* before annotations, if present
  private long offsetOfLastU2Element() {
    int offset = 0;
    if (hasMethodAnnotations()) offset++;
    if (hasParameterAnnotations()) offset++;
    if (hasTypeAnnotations()) offset++;
    if (hasDefaultAnnotations()) offset++;
    long wordSize = VM.getVM().getObjectHeap().getOopSize();
    return (getSize() * wordSize) - (offset * wordSize) - sizeofShort;
  }

  // Offset of the generic signature index
  private long offsetOfGenericSignatureIndex() {
    return offsetOfLastU2Element();
  }

  private long offsetOfMethodParametersLength() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(hasMethodParameters(), "should only be called if table is present");
    }
    return hasGenericSignature() ? offsetOfLastU2Element() - sizeofShort :
                                   offsetOfLastU2Element();
  }

  private int getMethodParametersLength() {
      if (hasMethodParameters())
          return (int) getAddress().getCIntegerAt(offsetOfMethodParametersLength(), 2, true);
      else
          return 0;
  }

  // Offset of start of checked exceptions
  private long offsetOfMethodParameters() {
    long offset = offsetOfMethodParametersLength();
    long length = getMethodParametersLength();
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(length > 0, "should only be called if method parameter information is present");
    }
    offset -= length * methodParametersElementSize;
    return offset;
  }

  private long offsetOfCheckedExceptionsLength() {
    if (hasMethodParameters())
      return offsetOfMethodParameters() - sizeofShort;
    else {
      return hasGenericSignature() ? offsetOfLastU2Element() - sizeofShort :
                                     offsetOfLastU2Element();
    }
  }

  private int getCheckedExceptionsLength() {
    if (hasCheckedExceptions()) {
      return (int) getAddress().getCIntegerAt(offsetOfCheckedExceptionsLength(), 2, true);
    } else {
      return 0;
    }
  }

  // Offset of start of checked exceptions
  private long offsetOfCheckedExceptions() {
    long offset = offsetOfCheckedExceptionsLength();
    long length = getCheckedExceptionsLength();
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(length > 0, "should only be called if table is present");
    }
    offset -= length * checkedExceptionElementSize;
    return offset;
  }

  private int getLineNumberTableLength() {
    int len = 0;
    if (hasLineNumberTable()) {
      CompressedLineNumberReadStream stream =
        new CompressedLineNumberReadStream(getAddress(), (int) offsetOfCompressedLineNumberTable());
      while (stream.readPair()) {
        len += 1;
      }
    }
    return len;
  }

  private int getLocalVariableTableLength() {
    if (hasLocalVariableTable()) {
      return (int) getAddress().getCIntegerAt(offsetOfLocalVariableTableLength(), 2, true);
    } else {
      return 0;
    }
  }

  // Offset of local variable table length
  private long offsetOfLocalVariableTableLength() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(hasLocalVariableTable(), "should only be called if table is present");
    }

    if (hasExceptionTable()) {
      return offsetOfExceptionTable() - sizeofShort;
    } else if (hasCheckedExceptions()) {
      return offsetOfCheckedExceptions() - sizeofShort;
    } else if (hasMethodParameters()) {
      return offsetOfMethodParameters() - sizeofShort;
    } else {
      return hasGenericSignature() ? offsetOfLastU2Element() - sizeofShort :
                                     offsetOfLastU2Element();
    }
  }

  private long offsetOfLocalVariableTable() {
    long offset = offsetOfLocalVariableTableLength();
    long length = getLocalVariableTableLength();
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(length > 0, "should only be called if table is present");
    }
    offset -= length * localVariableTableElementSize;
    return offset;
  }

  private int getExceptionTableLength() {
    if (hasExceptionTable()) {
      return (int) getAddress().getCIntegerAt(offsetOfExceptionTableLength(), 2, true);
    } else {
      return 0;
    }
  }

  private long offsetOfExceptionTableLength() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(hasExceptionTable(), "should only be called if table is present");
    }
    if (hasCheckedExceptions()) {
      return offsetOfCheckedExceptions() - sizeofShort;
    } else if (hasMethodParameters()) {
      return offsetOfMethodParameters() - sizeofShort;
    } else {
      return hasGenericSignature() ? offsetOfLastU2Element() - sizeofShort :
                                     offsetOfLastU2Element();
    }
  }

  private long offsetOfExceptionTable() {
    long offset = offsetOfExceptionTableLength();
    long length = getExceptionTableLength();
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(length > 0, "should only be called if table is present");
    }
    offset -= length * exceptionTableElementSize;
    return offset;
  }

}