/*

 * Copyright 2000-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

package sun.jvm.hotspot.runtime;

import java.util.*;

import sun.jvm.hotspot.debugger.*;

import sun.jvm.hotspot.types.*;

public class Thread extends VMObject {

  private static long tlabFieldOffset;

  private static CIntegerField suspendFlagsField;

  // Thread::SuspendFlags enum constants

  private static int EXTERNAL_SUSPEND;

  private static int EXT_SUSPENDED;

  private static int HAS_ASYNC_EXCEPTION;

  private static AddressField activeHandlesField;

  private static AddressField currentPendingMonitorField;

  private static AddressField currentWaitingMonitorField;

  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("Thread");

    suspendFlagsField = type.getCIntegerField("_suspend_flags");

    EXTERNAL_SUSPEND = db.lookupIntConstant("Thread::_external_suspend").intValue();

    EXT_SUSPENDED = db.lookupIntConstant("Thread::_ext_suspended").intValue();

    HAS_ASYNC_EXCEPTION = db.lookupIntConstant("Thread::_has_async_exception").intValue();

    tlabFieldOffset    = type.getField("_tlab").getOffset();

    activeHandlesField = type.getAddressField("_active_handles");

    currentPendingMonitorField = type.getAddressField("_current_pending_monitor");

    currentWaitingMonitorField = type.getAddressField("_current_waiting_monitor");

  }

  public Thread(Address addr) {

    super(addr);

  }

  public int suspendFlags() {

    return (int) suspendFlagsField.getValue(addr);

  }

  public boolean isExternalSuspend() {

    return (suspendFlags() & EXTERNAL_SUSPEND) != 0;

  }

  public boolean isExtSuspended() {

    return (suspendFlags() & EXT_SUSPENDED) != 0;

  }

  public boolean isBeingExtSuspended() {

    return isExtSuspended() || isExternalSuspend();

  }

  // historical usage: checked for VM or external suspension

  public boolean isAnySuspended() {

    return isExtSuspended();

  }

  public boolean hasAsyncException() {

    return (suspendFlags() & HAS_ASYNC_EXCEPTION) != 0;

  }

  public ThreadLocalAllocBuffer tlab() {

    return new ThreadLocalAllocBuffer(addr.addOffsetTo(tlabFieldOffset));

  }

  public JNIHandleBlock activeHandles() {

    Address a = activeHandlesField.getAddress(addr);

    if (a == null) {

      return null;

    }

    return new JNIHandleBlock(a);

  }

  public boolean   isVMThread()                { return false; }

  public boolean   isJavaThread()              { return false; }

  public boolean   isCompilerThread()          { return false; }

  public boolean   isHiddenFromExternalView()  { return false; }

  public boolean   isJvmtiAgentThread()        { return false; }

  public boolean   isWatcherThread()           { return false; }

  public boolean   isConcurrentMarkSweepThread() { return false; }

  public boolean   isLowMemoryDetectorThread() { return false; }

  /** Memory operations */

  public void oopsDo(AddressVisitor oopVisitor) {

    // FIXME: Empty for now; will later traverse JNI handles and

    // pending exception

  }

  public ObjectMonitor getCurrentPendingMonitor() {

    Address monitorAddr = currentPendingMonitorField.getValue(addr);

    if (monitorAddr == null) {

      return null;

    }

    return new ObjectMonitor(monitorAddr);

  }

  public ObjectMonitor getCurrentWaitingMonitor() {

    Address monitorAddr = currentWaitingMonitorField.getValue(addr);

    if (monitorAddr == null) {

      return null;

    }

    return new ObjectMonitor(monitorAddr);

  }

  public boolean isLockOwned(Address lock) {

    if (isInStack(lock)) return true;

    return false;

  }

  public boolean isInStack(Address a) {

    // In the Serviceability Agent we need access to the thread's

    // stack pointer to be able to answer this question. Since it is

    // only a debugging system at the moment we need access to the

    // underlying thread, which is only present for Java threads; see

    // JavaThread.java.

    return false;

  }

  /** Assistance for ObjectMonitor implementation */

  Address threadObjectAddress() { return addr; }

}