/* GNU Objective C Runtime Thread Interface   Copyright (C) 1996, 1997 Free Software Foundation, Inc.   Contributed by Galen C. Hunt (gchunt@cs.rochester.edu)This file is part of GCC.GCC is free software; you can redistribute it and/or modify it under theterms of the GNU General Public License as published by the Free SoftwareFoundation; either version 2, or (at your option) any later version.GCC is distributed in the hope that it will be useful, but WITHOUT ANYWARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESSFOR A PARTICULAR PURPOSE.  See the GNU General Public License for moredetails.You should have received a copy of the GNU General Public License along withGCC; see the file COPYING.  If not, write to the Free SoftwareFoundation, 51 Franklin Street, Fifth Floor,Boston, MA 02110-1301, 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 "objc/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 void __attribute__((noreturn))__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_tobjc_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)    {      /* failed! */      objc_mutex_unlock (__objc_runtime_mutex);      objc_free (istate);      return NULL;    }  /* Increment our thread counter */  __objc_runtime_threads_alive++;  objc_mutex_unlock (__objc_runtime_mutex);  return thread_id;}/* Set the current thread's priority. */intobjc_thread_set_priority (int priority){  /* Call the backend */  return __objc_thread_set_priority (priority);}/* Return the current thread's priority. */intobjc_thread_get_priority (void){  /* Call the backend */  return __objc_thread_get_priority ();}/*  Yield our process time to another thread.  Any BUSY waiting that is done  by a thread should use this function to make sure that other threads can  make progress even on a lazy uniprocessor system.  */voidobjc_thread_yield (void){  /* Call the backend */  __objc_thread_yield ();}/*  Terminate the current tread.  Doesn't return.  Actually, if it failed returns -1.  */intobjc_thread_exit (void){  /* Decrement our counter of the number of threads alive */  objc_mutex_lock (__objc_runtime_mutex);  __objc_runtime_threads_alive--;  objc_mutex_unlock (__objc_runtime_mutex);  /* Call the backend to terminate the thread */  return __objc_thread_exit ();}/*  Returns an integer value which uniquely describes a thread.  Must not be  NULL which is reserved as a marker for "no thread".  */objc_thread_tobjc_thread_id (void){  /* Call the backend */  return __objc_thread_id ();}/*  Sets the thread's local storage pointer.   Returns 0 if successful or -1 if failed.  */intobjc_thread_set_data (void *value){  /* Call the backend */  return __objc_thread_set_data (value);}/*  Returns the thread's local storage pointer.  Returns NULL on failure.  */void *objc_thread_get_data (void){  /* Call the backend */  return __objc_thread_get_data ();}/* Frontend mutex functions *//*  Allocate a mutex.  Return the mutex pointer if successful or NULL if the  allocation failed for any reason.  */objc_mutex_tobjc_mutex_allocate (void){  objc_mutex_t mutex;  /* Allocate the mutex structure */  if (! (mutex = (objc_mutex_t)objc_malloc (sizeof (struct objc_mutex))))    return NULL;  /* Call backend to create the mutex */  if (__objc_mutex_allocate (mutex))    {      /* failed! */      objc_free (mutex);      return NULL;    }  /* Initialize mutex */  mutex->owner = NULL;  mutex->depth = 0;  return mutex;}/*  Deallocate a mutex.  Note that this includes an implicit mutex_lock to  insure that no one else is using the lock.  It is legal to deallocate  a lock if we have a lock on it, but illegal to deallocate a lock held  by anyone else.  Returns the number of locks on the thread.  (1 for deallocate).  */intobjc_mutex_deallocate (objc_mutex_t mutex){  int depth;  /* Valid mutex? */  if (! mutex)    return -1;  /* Acquire lock on mutex */  depth = objc_mutex_lock (mutex);  /* Call backend to destroy mutex */  if (__objc_mutex_deallocate (mutex))    return -1;  /* Free the mutex structure */  objc_free (mutex);  /* Return last depth */  return depth;}/*  Grab a lock on a mutex.  If this thread already has a lock on this mutex  then we increment the lock count.  If another thread has a lock on the   mutex we block and wait for the thread to release the lock.  Returns the lock count on the mutex held by this thread.  */intobjc_mutex_lock (objc_mutex_t mutex){  objc_thread_t thread_id;  int status;  /* Valid mutex? */  if (! mutex)    return -1;  /* If we already own the lock then increment depth */  thread_id = __objc_thread_id ();  if (mutex->owner == thread_id)    return ++mutex->depth;  /* Call the backend to lock the mutex */  status = __objc_mutex_lock (mutex);  /* Failed? */  if (status)    return status;  /* Successfully locked the thread */  mutex->owner = thread_id;  return mutex->depth = 1;}/*  Try to grab a lock on a mutex.  If this thread already has a lock on  this mutex then we increment the lock count and return it.  If another  thread has a lock on the mutex returns -1.  */intobjc_mutex_trylock (objc_mutex_t mutex){  objc_thread_t thread_id;  int status;  /* Valid mutex? */  if (! mutex)    return -1;  /* If we already own the lock then increment depth */   thread_id = __objc_thread_id ();  if (mutex->owner == thread_id)    return ++mutex->depth;      /* Call the backend to try to lock the mutex */  status = __objc_mutex_trylock (mutex);  /* Failed? */  if (status)    return status;  /* Successfully locked the thread */  mutex->owner = thread_id;  return mutex->depth = 1;}/*   Unlocks the mutex by one level.  Decrements the lock count on this mutex by one.  If the lock count reaches zero, release the lock on the mutex.  Returns the lock count on the mutex.  It is an error to attempt to unlock a mutex which this thread   doesn't hold in which case return -1 and the mutex is unaffected.  */intobjc_mutex_unlock (objc_mutex_t mutex){  objc_thread_t thread_id;  int status;  /* Valid mutex? */  if (! mutex)    return -1;  /* If another thread owns the lock then abort */  thread_id = __objc_thread_id ();  if (mutex->owner != thread_id)    return -1;  /* Decrement depth and return */  if (mutex->depth > 1)    return --mutex->depth;  /* Depth down to zero so we are no longer the owner */  mutex->depth = 0;  mutex->owner = NULL;  /* Have the backend unlock the mutex */  status = __objc_mutex_unlock (mutex);  /* Failed? */  if (status)    return status;  return 0;}/* Frontend condition mutex functions *//*  Allocate a condition.  Return the condition pointer if successful or NULL  if the allocation failed for any reason.  */objc_condition_t objc_condition_allocate (void){  objc_condition_t condition;      /* Allocate the condition mutex structure */  if (! (condition = 	 (objc_condition_t) objc_malloc (sizeof (struct objc_condition))))    return NULL;  /* Call the backend to create the condition mutex */  if (__objc_condition_allocate (condition))    {      /* failed! */      objc_free (condition);      return NULL;    }  /* Success! */  return condition;}/*  Deallocate a condition. Note that this includes an implicit   condition_broadcast to insure that waiting threads have the opportunity  to wake.  It is legal to dealloc a condition only if no other  thread is/will be using it. Here we do NOT check for other threads  waiting but just wake them up.  */intobjc_condition_deallocate (objc_condition_t condition){  /* Broadcast the condition */  if (objc_condition_broadcast (condition))    return -1;  /* Call the backend to destroy */  if (__objc_condition_deallocate (condition))    return -1;  /* Free the condition mutex structure */  objc_free (condition);  return 0;}/*  Wait on the condition unlocking the mutex until objc_condition_signal ()  or objc_condition_broadcast () are called for the same condition. The  given mutex *must* have the depth set to 1 so that it can be unlocked  here, so that someone else can lock it and signal/broadcast the condition.  The mutex is used to lock access to the shared data that make up the  "condition" predicate.  */intobjc_condition_wait (objc_condition_t condition, objc_mutex_t mutex){  objc_thread_t thread_id;  /* Valid arguments? */  if (! mutex || ! condition)    return -1;  /* Make sure we are owner of mutex */  thread_id = __objc_thread_id ();  if (mutex->owner != thread_id)    return -1;  /* Cannot be locked more than once */  if (mutex->depth > 1)    return -1;  /* Virtually unlock the mutex */  mutex->depth = 0;  mutex->owner = (objc_thread_t)NULL;  /* Call the backend to wait */  __objc_condition_wait (condition, mutex);  /* Make ourselves owner of the mutex */  mutex->owner = thread_id;  mutex->depth = 1;  return 0;}/*  Wake up all threads waiting on this condition. It is recommended that   the called would lock the same mutex as the threads in objc_condition_wait  before changing the "condition predicate" and make this call and unlock it  right away after this call.  */intobjc_condition_broadcast (objc_condition_t condition){  /* Valid condition mutex? */  if (! condition)    return -1;  return __objc_condition_broadcast (condition);}/*  Wake up one thread waiting on this condition. It is recommended that   the called would lock the same mutex as the threads in objc_condition_wait  before changing the "condition predicate" and make this call and unlock it  right away after this call.  */intobjc_condition_signal (objc_condition_t condition){  /* Valid condition mutex? */  if (! condition)    return -1;  return __objc_condition_signal (condition);}/* Make the objc thread system aware that a thread which is managed   (started, stopped) by external code could access objc facilities   from now on.  This is used when you are interfacing with some   external non-objc-based environment/system - you must call   objc_thread_add () before an alien thread makes any calls to   Objective-C.  Do not cause the _objc_became_multi_threaded hook to   be executed. */void objc_thread_add (void){  objc_mutex_lock (__objc_runtime_mutex);  __objc_is_multi_threaded = 1;  __objc_runtime_threads_alive++;  objc_mutex_unlock (__objc_runtime_mutex);  }/* Make the objc thread system aware that a thread managed (started,   stopped) by some external code will no longer access objc and thus   can be forgotten by the objc thread system.  Call   objc_thread_remove () when your alien thread is done with making   calls to Objective-C. */voidobjc_thread_remove (void){  objc_mutex_lock (__objc_runtime_mutex);  __objc_runtime_threads_alive--;  objc_mutex_unlock (__objc_runtime_mutex);  }/* End of File */