/* than.c: ANSI THREADS MANAGER
 *
 *  $Id$
 *  Copyright (c) 2001-2014 Ravenbrook Limited.  See end of file for license.
 *
 *  This is a single-threaded implementation of the threads manager.
 *  Has stubs for thread suspension.
 *  See <design/thread-manager/>.
 *
 *  .single: We only expect at most one thread on the ring.
 *
 *  This supports the <code/th.h>
 */

#include "mpm.h"

SRCID(than, "$Id$");


typedef struct mps_thr_s {      /* ANSI fake thread structure */
  Sig sig;                      /* <design/sig/> */
  Serial serial;                /* from arena->threadSerial */
  Arena arena;                  /* owning arena */
  RingStruct arenaRing;         /* attaches to arena */
} ThreadStruct;


Bool ThreadCheck(Thread thread)
{
  CHECKS(Thread, thread);
  CHECKU(Arena, thread->arena);
  CHECKL(thread->serial < thread->arena->threadSerial);
  CHECKD_NOSIG(Ring, &thread->arenaRing);
  return TRUE;
}


Bool ThreadCheckSimple(Thread thread)
{
  CHECKS(Thread, thread);
  return TRUE;
}


Res ThreadRegister(Thread *threadReturn, Arena arena)
{
  Res res;
  Thread thread;
  Ring ring;
  void *p;

  AVER(threadReturn != NULL);

  res = ControlAlloc(&p, arena, sizeof(ThreadStruct),
                     /* withReservoirPermit */ FALSE);
  if(res != ResOK) return res;
  thread = (Thread)p;

  thread->arena = arena;
  RingInit(&thread->arenaRing);

  thread->sig = ThreadSig;
  thread->serial = arena->threadSerial;
  ++arena->threadSerial;

  AVERT(Thread, thread);

  ring = ArenaThreadRing(arena);
  AVER(RingCheckSingle(ring));  /* .single */

  RingAppend(ring, &thread->arenaRing);

  *threadReturn = thread;
  return ResOK;
}


void ThreadDeregister(Thread thread, Arena arena)
{
  AVERT(Thread, thread);
  AVERT(Arena, arena);

  RingRemove(&thread->arenaRing);

  thread->sig = SigInvalid;

  RingFinish(&thread->arenaRing);

  ControlFree(arena, thread, sizeof(ThreadStruct));
}


void ThreadRingSuspend(Ring threadRing)
{
  AVERT(Ring, threadRing);
  return;
}

void ThreadRingResume(Ring threadRing)
{
  AVERT(Ring, threadRing);
  return;
}

Thread ThreadRingThread(Ring threadRing)
{
  Thread thread;
  AVERT(Ring, threadRing);
  thread = RING_ELT(Thread, arenaRing, threadRing);
  AVERT(Thread, thread);
  return thread;
}


/* Must be thread-safe.  See <design/interface-c/#thread-safety>. */
Arena ThreadArena(Thread thread)
{
  /* Can't AVER thread as that would not be thread-safe */
  /* AVERT(Thread, thread); */
  return thread->arena;
}


Res ThreadScan(ScanState ss, Thread thread, void *stackBot)
{
  UNUSED(thread);
  return StackScan(ss, stackBot);
}


Res ThreadDescribe(Thread thread, mps_lib_FILE *stream)
{
  Res res;
 
  res = WriteF(stream,
               "Thread $P ($U) {\n", (WriteFP)thread, (WriteFU)thread->serial,
               "  arena $P ($U)\n", 
               (WriteFP)thread->arena, (WriteFU)thread->arena->serial,
               "} Thread $P ($U)\n", (WriteFP)thread, (WriteFU)thread->serial,
               NULL);
  if(res != ResOK) return res;

  return ResOK;
}


/* C. COPYRIGHT AND LICENSE
 *
 * Copyright (C) 2001-2014 Ravenbrook Limited <http://www.ravenbrook.com/>.
 * All rights reserved.  This is an open source license.  Contact
 * Ravenbrook for commercial licensing options.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * 3. Redistributions in any form must be accompanied by information on how
 * to obtain complete source code for this software and any accompanying
 * software that uses this software.  The source code must either be
 * included in the distribution or be available for no more than the cost
 * of distribution plus a nominal fee, and must be freely redistributable
 * under reasonable conditions.  For an executable file, complete source
 * code means the source code for all modules it contains. It does not
 * include source code for modules or files that typically accompany the
 * major components of the operating system on which the executable file
 * runs.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */