/*

 * 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

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 */

package sun.jvm.hotspot.runtime;

import java.util.*;

import sun.jvm.hotspot.oops.*;

import sun.jvm.hotspot.utilities.*;

import sun.jvm.hotspot.debugger.*;

import sun.jvm.hotspot.types.*;

public class ObjectSynchronizer {

  static {

    VM.registerVMInitializedObserver(new Observer() {

        public void update(Observable o, Object data) {

          initialize(VM.getVM().getTypeDataBase());

        }

      });

  }

  private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {

    Type type;

    try {

      type = db.lookupType("ObjectSynchronizer");

      AddressField blockListField;

      blockListField = type.getAddressField("gBlockList");

      gBlockListAddr = blockListField.getValue();

      blockSize = db.lookupIntConstant("ObjectSynchronizer::_BLOCKSIZE").intValue();

    } catch (RuntimeException e) { }

    type = db.lookupType("ObjectMonitor");

    objectMonitorTypeSize = type.getSize();

  }

  public long identityHashValueFor(Oop obj) {

    Mark mark = obj.getMark();

    if (mark.isUnlocked()) {

      // FIXME: can not generate marks in debugging system

      return mark.hash();

    } else if (mark.hasMonitor()) {

      ObjectMonitor monitor = mark.monitor();

      Mark temp = monitor.header();

      return temp.hash();

    } else {

      if (Assert.ASSERTS_ENABLED) {

        Assert.that(VM.getVM().isDebugging(), "Can not access displaced header otherwise");

      }

      if (mark.hasDisplacedMarkHelper()) {

        Mark temp = mark.displacedMarkHelper();

        return temp.hash();

      }

      // FIXME: can not do anything else here in debugging system

      return 0;

    }

  }

  public static Iterator objectMonitorIterator() {

    if (gBlockListAddr != null) {

      return new ObjectMonitorIterator();

    } else {

      return null;

    }

  }

  private static class ObjectMonitorIterator implements Iterator {

    // JVMTI raw monitors are not pointed by gBlockList

    // and are not included by this Iterator. May add them later.

    ObjectMonitorIterator() {

      blockAddr = gBlockListAddr;

      index = blockSize - 1;

      block = new ObjectMonitor(blockAddr);

    }

    public boolean hasNext() {

      return (index > 0 || block.freeNext() != null);

    }

    public Object next() {

      Address addr;

      if (index > 0) {

        addr = blockAddr.addOffsetTo(index*objectMonitorTypeSize);

      } else {

        blockAddr = block.freeNext();

        index = blockSize - 1;

        addr = blockAddr.addOffsetTo(index*objectMonitorTypeSize);

      }

      index --;

      return new ObjectMonitor(addr);

    }

    public void remove() {

      throw new UnsupportedOperationException();

    }

    private ObjectMonitor block;

    private int index;

    private Address blockAddr;

  }

  private static Address gBlockListAddr;

  private static int blockSize;

  private static long objectMonitorTypeSize;

}