/*

 * Copyright (c) 1997, 2019, 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.

 *

 */

#include "runtime/frame.hpp"

#include "runtime/handles.hpp"

#include "runtime/javaFrameAnchor.hpp"

#include "runtime/objectMonitor.hpp"

#include "utilities/macros.hpp"

// The OSThread class holds OS-specific thread information.  It is equivalent

// to the sys_thread_t structure of the classic JVM implementation.

// The thread states represented by the ThreadState values are platform-specific

// and are likely to be only approximate, because most OSes don't give you access

// to precise thread state information.

// Note: the ThreadState is legacy code and is not correctly implemented.

// Uses of ThreadState need to be replaced by the state in the JavaThread.

enum ThreadState {

  ALLOCATED,                    // Memory has been allocated but not initialized

  INITIALIZED,                  // The thread has been initialized but yet started

  RUNNABLE,                     // Has been started and is runnable, but not necessarily running

  MONITOR_WAIT,                 // Waiting on a contended monitor lock

  CONDVAR_WAIT,                 // Waiting on a condition variable

  OBJECT_WAIT,                  // Waiting on an Object.wait() call

  BREAKPOINTED,                 // Suspended at breakpoint

  SLEEPING,                     // Thread.sleep()

  ZOMBIE                        // All done, but not reclaimed yet

};

typedef int (*OSThreadStartFunc)(void*);

class OSThread: public CHeapObj<mtThread> {

  friend class VMStructs;

  friend class JVMCIVMStructs;

 private:

  OSThreadStartFunc _start_proc;  // Thread start routine

  void* _start_parm;              // Thread start routine parameter

  volatile ThreadState _state;    // Thread state *hint*

  volatile jint _interrupted;     // Thread.isInterrupted state

  // Note:  _interrupted must be jint, so that Java intrinsics can access it.

  // The value stored there must be either 0 or 1.  It must be possible

  // for Java to emulate Thread.currentThread().isInterrupted() by performing

  // the double indirection Thread::current()->_osthread->_interrupted.

  // Methods

 public:

  void set_state(ThreadState state)                { _state = state; }

  ThreadState get_state()                          { return _state; }

  OSThread(OSThreadStartFunc start_proc, void* start_parm);

  ~OSThread();

  // Accessors

  OSThreadStartFunc start_proc() const              { return _start_proc; }

  void set_start_proc(OSThreadStartFunc start_proc) { _start_proc = start_proc; }

  void* start_parm() const                          { return _start_parm; }

  void set_start_parm(void* start_parm)             { _start_parm = start_parm; }

  volatile bool interrupted() const                 { return _interrupted != 0; }

  void set_interrupted(bool z)                      { _interrupted = z ? 1 : 0; }

  // Printing

  void print_on(outputStream* st) const;

  void print() const                                { print_on(tty); }

  // For java intrinsics:

  static ByteSize interrupted_offset()            { return byte_offset_of(OSThread, _interrupted); }

  // Platform dependent stuff

#include OS_HEADER(osThread)

 public:

  static ByteSize thread_id_offset()              { return byte_offset_of(OSThread, _thread_id); }

  static size_t thread_id_size()                  { return sizeof(thread_id_t); }

  thread_id_t thread_id() const                   { return _thread_id; }

  void set_thread_id(thread_id_t id)              { _thread_id = id; }

 private:

  // _thread_id is kernel thread id (similar to LWP id on Solaris). Each

  // thread has a unique thread_id (BsdThreads or NPTL). It can be used

  // to access /proc.

  thread_id_t _thread_id;

};

// Utility class for use with condition variables:

class OSThreadWaitState : public StackObj {

  OSThread*   _osthread;

  ThreadState _old_state;

 public:

  OSThreadWaitState(OSThread* osthread, bool is_object_wait) {

    _osthread  = osthread;

    _old_state = osthread->get_state();

    if (is_object_wait) {

      osthread->set_state(OBJECT_WAIT);

    } else {

      osthread->set_state(CONDVAR_WAIT);

    }

  }

  ~OSThreadWaitState() {

    _osthread->set_state(_old_state);

  }

};

// Utility class for use with contended monitors:

class OSThreadContendState : public StackObj {

  OSThread*   _osthread;

  ThreadState _old_state;

 public:

  OSThreadContendState(OSThread* osthread) {

    _osthread  = osthread;

    _old_state = osthread->get_state();

    osthread->set_state(MONITOR_WAIT);

  }

  ~OSThreadContendState() {

    _osthread->set_state(_old_state);

  }

};