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// Copyright 2009 The Go Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#include "config.h"

#include "runtime.h"

#include <errno.h>

#include <stdlib.h>

#include <time.h>

#include <semaphore.h>

/* If we don't have sem_timedwait, use pthread_cond_timedwait instead.

   We don't always use condition variables because on some systems

   pthread_mutex_lock and pthread_mutex_unlock must be called by the

   same thread.  That is never true of semaphores.  */

struct go_sem

{

  sem_t sem;

#ifndef HAVE_SEM_TIMEDWAIT

  int timedwait;

  pthread_mutex_t mutex;

  pthread_cond_t cond;

#endif

};

/* Create a semaphore.  */

uintptr

runtime_semacreate(void)

{

  struct go_sem *p;

  /* Call malloc rather than runtime_malloc.  This will allocate space

     on the C heap.  We can't call runtime_malloc here because it

     could cause a deadlock.  */

  p = malloc (sizeof (struct go_sem));

  if (sem_init (&p->sem, 0, 0) != 0)

    runtime_throw ("sem_init");

#ifndef HAVE_SEM_TIMEDWAIT

  if (pthread_mutex_init (&p->mutex, NULL) != 0)

    runtime_throw ("pthread_mutex_init");

  if (pthread_cond_init (&p->cond, NULL) != 0)

    runtime_throw ("pthread_cond_init");

#endif

  return (uintptr) p;

}

/* Acquire m->waitsema.  */

int32

runtime_semasleep (int64 ns)

{

  M *m;

  struct go_sem *sem;

  int r;

  m = runtime_m ();

  sem = (struct go_sem *) m->waitsema;

  if (ns >= 0)

    {

      int64 abs;

      struct timespec ts;

      int err;

      abs = ns + runtime_nanotime ();

      ts.tv_sec = abs / 1000000000LL;

      ts.tv_nsec = abs % 1000000000LL;

      err = 0;

#ifdef HAVE_SEM_TIMEDWAIT

      r = sem_timedwait (&sem->sem, &ts);

      if (r != 0)

        err = errno;

#else

      if (pthread_mutex_lock (&sem->mutex) != 0)

        runtime_throw ("pthread_mutex_lock");

      while ((r = sem_trywait (&sem->sem)) != 0)

        {

          r = pthread_cond_timedwait (&sem->cond, &sem->mutex, &ts);

          if (r != 0)

            {

              err = r;

              break;

            }

        }

      if (pthread_mutex_unlock (&sem->mutex) != 0)

        runtime_throw ("pthread_mutex_unlock");

#endif

      if (err != 0)

        {

          if (err == ETIMEDOUT || err == EAGAIN || err == EINTR)

            return -1;

          runtime_throw ("sema_timedwait");

        }

      return 0;

    }

  while (sem_wait (&sem->sem) != 0)

    {

      if (errno == EINTR)

        continue;

      runtime_throw ("sem_wait");

    }

  return 0;

}

/* Wake up mp->waitsema.  */

void

runtime_semawakeup (M *mp)

{

  struct go_sem *sem;

  sem = (struct go_sem *) mp->waitsema;

  if (sem_post (&sem->sem) != 0)

    runtime_throw ("sem_post");

#ifndef HAVE_SEM_TIMEDWAIT

  if (pthread_mutex_lock (&sem->mutex) != 0)

    runtime_throw ("pthread_mutex_lock");

  if (pthread_cond_broadcast (&sem->cond) != 0)

    runtime_throw ("pthread_cond_broadcast");

  if (pthread_mutex_unlock (&sem->mutex) != 0)

    runtime_throw ("pthread_mutex_unlock");

#endif

}

void

runtime_osinit (void)

{

}

void

runtime_goenvs (void)

{

  runtime_goenvs_unix ();

}