source: trunk/src/gcc/libobjc/thr.c@ 80

/* GNU Objective C Runtime Thread Interface
   Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   Contributed by Galen C. Hunt ([email protected])

This file is part of GNU CC.

GNU CC 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 2, or (at your option) any later version.

GNU CC 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.

You should have received a copy of the GNU General Public License along with
GNU CC; see the file COPYING.  If not, write to the Free Software
Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* As a special exception, if you link this library with files compiled with
   GCC to produce an executable, this does not cause the resulting executable
   to be covered by the GNU General Public License. This exception does not
   however invalidate any other reasons why the executable file might be
   covered by the GNU General Public License.  */

#include <stdlib.h>
#include "runtime.h"

/* Global exit status. */
int __objc_thread_exit_status = 0;

/* Flag which lets us know if we ever became multi threaded */
int __objc_is_multi_threaded = 0;

/* The hook function called when the runtime becomes multi threaded */
objc_thread_callback _objc_became_multi_threaded = NULL;

/*
  Use this to set the hook function that will be called when the 
  runtime initially becomes multi threaded.
  The hook function is only called once, meaning only when the 
  2nd thread is spawned, not for each and every thread.

  It returns the previous hook function or NULL if there is none.

  A program outside of the runtime could set this to some function so
  it can be informed; for example, the GNUstep Base Library sets it 
  so it can implement the NSBecomingMultiThreaded notification.
  */
objc_thread_callback objc_set_thread_callback(objc_thread_callback func)
{
  objc_thread_callback temp = _objc_became_multi_threaded;
  _objc_became_multi_threaded = func;
  return temp;
}

/*
  Private functions

  These functions are utilized by the frontend, but they are not
  considered part of the public interface.
  */

/*
  First function called in a thread, starts everything else.

  This function is passed to the backend by objc_thread_detach
  as the starting function for a new thread.
 */
struct __objc_thread_start_state
{
  SEL selector;
  id object;
  id argument;
};

static volatile void
__objc_thread_detach_function(struct __objc_thread_start_state *istate)
{
  /* Valid state? */
  if (istate) {
    id (*imp)(id,SEL,id);
    SEL selector = istate->selector;
    id object   = istate->object;
    id argument = istate->argument;

    /* Don't need anymore so free it */
    objc_free(istate);

    /* Clear out the thread local storage */
    objc_thread_set_data(NULL);

    /* Check to see if we just became multi threaded */
    if (!__objc_is_multi_threaded)
      {
        __objc_is_multi_threaded = 1;

        /* Call the hook function */
        if (_objc_became_multi_threaded != NULL)
          (*_objc_became_multi_threaded)();
      }

    /* Call the method */
    if ((imp = (id(*)(id, SEL, id))objc_msg_lookup(object, selector)))
        (*imp)(object, selector, argument);
    else
      objc_error(object, OBJC_ERR_UNIMPLEMENTED,
                 "objc_thread_detach called with bad selector.\n");
  }
  else
    objc_error(nil, OBJC_ERR_BAD_STATE,
               "objc_thread_detach called with NULL state.\n");

  /* Exit the thread */
  objc_thread_exit();
}

/*
  Frontend functions

  These functions constitute the public interface to the Objective-C thread
  and mutex functionality.
  */

/* Frontend thread functions */

/*
  Detach a new thread of execution and return its id.  Returns NULL if fails.
  Thread is started by sending message with selector to object.  Message
  takes a single argument.
  */
objc_thread_t
objc_thread_detach(SEL selector, id object, id argument)
{
  struct __objc_thread_start_state *istate;
  objc_thread_t        thread_id = NULL;

  /* Allocate the state structure */
  if (!(istate = (struct __objc_thread_start_state *)
        objc_malloc(sizeof(*istate))))
    return NULL;

  /* Initialize the state structure */
  istate->selector = selector;
  istate->object = object;
  istate->argument = argument;

  /* lock access */
  objc_mutex_lock(__objc_runtime_mutex);

  /* Call the backend to spawn the thread */
  if ((thread_id = __objc_thread_detach((void *)__objc_thread_detach_function,
                                        istate)) == NULL)