libobjc/thr-posix.c

/* GNU Objective C Runtime Thread Interface for POSIX compliant threads
   Copyright (C) 1996, 1997, 2009 Free Software Foundation, Inc.
   Contributed by Galen C. Hunt (gchunt@cs.rochester.edu)
   Modified for Linux/Pthreads by Kai-Uwe Sattler (kus@iti.cs.uni-magdeburg.de)
   Modified for posix compliance by Chris Ball (cball@fmco.com)

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.

GCC 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 for more
details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */


#include "objc/thr.h"
#include "objc/runtime.h"
#include <pthread.h>

/* Key structure for maintaining thread specific storage */
static pthread_key_t _objc_thread_storage;
static pthread_attr_t _objc_thread_attribs;

/* Backend initialization functions */

/* Initialize the threads subsystem. */
int
__objc_init_thread_system(void)
{
  /* Initialize the thread storage key */
  if (pthread_key_create(&_objc_thread_storage, NULL) == 0)
    {
      /*
       * The normal default detach state for threads is PTHREAD_CREATE_JOINABLE
       * which causes threads to not die when you think they should.
	   */
      if (pthread_attr_init(&_objc_thread_attribs) == 0)
        {
          if (pthread_attr_setdetachstate(&_objc_thread_attribs, 
                                          PTHREAD_CREATE_DETACHED) == 0)
            return 0;
        }
    }

  return -1;
}

/* Close the threads subsystem. */
int
__objc_close_thread_system(void)
{
  if (pthread_key_delete(_objc_thread_storage) == 0)
    {
      if (pthread_attr_destroy(&_objc_thread_attribs) == 0)
        return 0;
    }

  return -1;
}

/* Backend thread functions */

/* Create a new thread of execution. */
objc_thread_t
__objc_thread_detach(void (*func)(void *arg), void *arg)
{
  objc_thread_t thread_id;
  pthread_t new_thread_handle;
  
  if (!(pthread_create(&new_thread_handle, &_objc_thread_attribs, 
                       (void *)func, arg)))
    thread_id = *(objc_thread_t *)&new_thread_handle;
  else
    thread_id = NULL;
  
  return thread_id;
}

/* Set the current thread's priority.
 *
 * Be aware that the default schedpolicy often disallows thread priorities.
 */
int
__objc_thread_set_priority(int priority)
{
  pthread_t thread_id = pthread_self();
  int policy;
  struct sched_param params;
  int priority_min, priority_max;

  if (pthread_getschedparam(thread_id, &policy, &params) == 0)
    {
      if ((priority_max = sched_get_priority_max(policy)) != 0)
        return -1;

      if ((priority_min = sched_get_priority_min(policy)) != 0)
        return -1;

      if (priority > priority_max)
        priority = priority_max;
      else if (priority < priority_min)
        priority = priority_min;
      params.sched_priority = priority;

      /*
       * The solaris 7 and several other man pages incorrectly state that
       * this should be a pointer to policy but pthread.h is universally
       * at odds with this.
       */
      if (pthread_setschedparam(thread_id, policy, &params) == 0)
        return 0;
    }
  return -1;
}

/* Return the current thread's priority. */
int
__objc_thread_get_priority(void)
{
  int policy;
  struct sched_param params;

  if (pthread_getschedparam(pthread_self(), &policy, &params) == 0)
    return params.sched_priority;
  else
    return -1;
}

/* Yield our process time to another thread. */
void
__objc_thread_yield(void)
{
  sched_yield();
}

/* Terminate the current thread. */
int
__objc_thread_exit(void)
{
  /* exit the thread */
  pthread_exit(&__objc_thread_exit_status);

  /* Failed if we reached here */
  return -1;
}

/* Returns an integer value which uniquely describes a thread. */
objc_thread_t
__objc_thread_id(void)
{
  pthread_t self = pthread_self();

  return *(objc_thread_t *)&self;
}

/* Sets the thread's local storage pointer. */
int
__objc_thread_set_data(void *value)
{
  if (pthread_setspecific(_objc_thread_storage, value) == 0)
    return 0;
  else
    return -1;
}

/* Returns the thread's local storage pointer. */
void *
__objc_thread_get_data(void)
{
  return pthread_getspecific(_objc_thread_storage);
}

/* Backend mutex functions */

/* Allocate a mutex. */
int
__objc_mutex_allocate(objc_mutex_t mutex)
{
  mutex->backend = objc_malloc(sizeof(pthread_mutex_t));

  if (pthread_mutex_init((pthread_mutex_t *)mutex->backend, NULL))
    {
      objc_free(mutex->backend);
      mutex->backend = NULL;
      return -1;
    }

  return 0;
}

/* Deallocate a mutex. */
int
__objc_mutex_deallocate(objc_mutex_t mutex)
{
  int count = 1;

  /*
   * Posix Threads specifically require that the thread be unlocked for
   * pthread_mutex_destroy to work.
   */

  while (count)
    {
      if ((count = pthread_mutex_unlock((pthread_mutex_t*)mutex->backend)) < 0)
        return -1;
    }

  if (pthread_mutex_destroy((pthread_mutex_t *)mutex->backend))
    return -1;

  objc_free(mutex->backend);
  mutex->backend = NULL;
  return 0;
}

/* Grab a lock on a mutex. */
int
__objc_mutex_lock(objc_mutex_t mutex)
{
  if (pthread_mutex_lock((pthread_mutex_t *)mutex->backend) == 0)
    return 0;
  else
    return -1;
}

/* Try to grab a lock on a mutex. */
int
__objc_mutex_trylock(objc_mutex_t mutex)
{
  if (pthread_mutex_trylock((pthread_mutex_t *)mutex->backend) == 0)
    return 0;
  else
    return -1;
}

/* Unlock the mutex */
int
__objc_mutex_unlock(objc_mutex_t mutex)
{
  if (pthread_mutex_unlock((pthread_mutex_t *)mutex->backend) == 0)
    return 0;
  else
    return -1;
}

/* Backend condition mutex functions */

/* Allocate a condition. */
int
__objc_condition_allocate(objc_condition_t condition)
{
  condition->backend = objc_malloc(sizeof(pthread_cond_t));

  if (pthread_cond_init((pthread_cond_t *)condition->backend, NULL))
    {
      objc_free(condition->backend);
      condition->backend = NULL;
      return -1;
    }

  return 0;
}

/* Deallocate a condition. */
int
__objc_condition_deallocate(objc_condition_t condition)
{
  if (pthread_cond_destroy((pthread_cond_t *)condition->backend))
    return -1;

  objc_free(condition->backend);
  condition->backend = NULL;
  return 0;
}

/* Wait on the condition */
int
__objc_condition_wait(objc_condition_t condition, objc_mutex_t mutex)
{
  if (pthread_cond_wait((pthread_cond_t *)condition->backend,
                        (pthread_mutex_t *)mutex->backend) == 0)
    return 0;
  else
    return -1;
}

/* Wake up all threads waiting on this condition. */
int
__objc_condition_broadcast(objc_condition_t condition)
{
  if (pthread_cond_broadcast((pthread_cond_t *)condition->backend) == 0)
    return 0;
  else
    return -1;
}

/* Wake up one thread waiting on this condition. */
int
__objc_condition_signal(objc_condition_t condition)
{
  if (pthread_cond_signal((pthread_cond_t *)condition->backend) == 0)
    return 0;
  else
    return -1;
}