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/* GNU Objective C Runtime Thread Implementation for PCThreads under Darwin.
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Copyright (C) 1996, 1997 Free Software Foundation, Inc.
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Contributed by Scott Christley <scottc@net-community.com>
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Condition functions added by: Mircea Oancea <mircea@first.elcom.pub.ro>
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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version 2, or (at your option) any later version.
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GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA. */
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/* As a special exception, if you link this library with files compiled with
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GCC to produce an executable, this does not cause the resulting executable
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to be covered by the GNU General Public License. This exception does not
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however invalidate any other reasons why the executable file might be
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covered by the GNU General Public License. */
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#include "GNUstepBase/objc-gnu2next.h"
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/* Key structure for maintaining thread specific storage */
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static pthread_key_t _objc_thread_storage;
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static pthread_attr_t _objc_thread_attribs;
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/* Global exit status. */
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int __objc_thread_exit_status = 0;
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/* Number of threads alive */
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int __objc_runtime_threads_alive = 0;
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/* Thread create/exit mutex */
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struct objc_mutex* __objc_runtime_mutex = NULL;
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/* Flag which lets us know if we ever became multi threaded */
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int __objc_is_multi_threaded = 0;
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/* The hook function called when the runtime becomes multi threaded */
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objc_thread_callback _objc_became_multi_threaded = NULL;
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Use this to set the hook function that will be called when the
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runtime initially becomes multi threaded.
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The hook function is only called once, meaning only when the
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2nd thread is spawned, not for each and every thread.
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It returns the previous hook function or NULL if there is none.
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A program outside of the runtime could set this to some function so
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it can be informed; for example, the GNUstep Base Library sets it
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so it can implement the NSBecomingMultiThreaded notification.
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objc_thread_callback objc_set_thread_callback(objc_thread_callback func)
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objc_thread_callback temp = _objc_became_multi_threaded;
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_objc_became_multi_threaded = func;
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These functions are utilized by the frontend, but they are not
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considered part of the public interface.
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First function called in a thread, starts everything else.
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This function is passed to the backend by objc_thread_detach
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as the starting function for a new thread.
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struct __objc_thread_start_state
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__objc_thread_detach(void (*func)(void *arg), void *arg);
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__objc_thread_detach_function(struct __objc_thread_start_state *istate)
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id (*imp)(id,SEL,id);
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SEL selector = istate->selector;
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id object = istate->object;
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id argument = istate->argument;
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/* Don't need anymore so free it */
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/* Clear out the thread local storage */
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objc_thread_set_data(NULL);
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/* Check to see if we just became multi threaded */
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if (!__objc_is_multi_threaded)
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__objc_is_multi_threaded = 1;
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/* Call the hook function */
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if (_objc_became_multi_threaded != NULL)
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(*_objc_became_multi_threaded)();
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/* Call the method */
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if ((imp = (id(*)(id, SEL, id))objc_msg_lookup(object, selector)))
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(*imp)(object, selector, argument);
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objc_error(object, OBJC_ERR_UNIMPLEMENTED,
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"objc_thread_detach called with bad selector.\n");
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objc_error(nil, OBJC_ERR_BAD_STATE,
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"objc_thread_detach called with NULL state.\n");
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/* Exit the thread */
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These functions constitute the public interface to the Objective-C thread
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and mutex functionality.
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/* Frontend thread functions */
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Detach a new thread of execution and return its id. Returns NULL if fails.
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Thread is started by sending message with selector to object. Message
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takes a single argument.
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objc_thread_detach(SEL selector, id object, id argument)
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struct __objc_thread_start_state *istate;
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objc_thread_t thread_id = NULL;
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/* Allocate the state structure */
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if (!(istate = (struct __objc_thread_start_state *)
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objc_malloc(sizeof(*istate))))
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/* Initialize the state structure */
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istate->selector = selector;
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istate->object = object;
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istate->argument = argument;
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objc_mutex_lock(__objc_runtime_mutex);
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/* Call the backend to spawn the thread */
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if ((thread_id = __objc_thread_detach((void *)__objc_thread_detach_function,
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objc_mutex_unlock(__objc_runtime_mutex);
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/* Increment our thread counter */
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__objc_runtime_threads_alive++;
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objc_mutex_unlock(__objc_runtime_mutex);
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/* Backend initialization functions */
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/* Initialize the threads subsystem. */
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__objc_init_thread_system(void)
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/* Initialize the thread storage key */
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if (pthread_key_create(&_objc_thread_storage, NULL) == 0)
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* The normal default detach state for threads is PTHREAD_CREATE_JOINABLE
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* which causes threads to not die when you think they should.
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if (pthread_attr_init(&_objc_thread_attribs) == 0)
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if (pthread_attr_setdetachstate(&_objc_thread_attribs,
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PTHREAD_CREATE_DETACHED) == 0)
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/* Close the threads subsystem. */
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__objc_close_thread_system(void)
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/* Destroy the thread storage key */
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if (pthread_key_delete(_objc_thread_storage) == 0)
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if (pthread_attr_destroy(&_objc_thread_attribs) == 0)
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/* Backend thread functions */
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/* Create a new thread of execution. */
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__objc_thread_detach(void (*func)(void *arg), void *arg)
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objc_thread_t thread_id;
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pthread_t new_thread_handle;
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if (!(pthread_create(&new_thread_handle, &_objc_thread_attribs,
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thread_id = *(objc_thread_t *)&new_thread_handle;
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/* Set the current thread's priority. */
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objc_thread_set_priority(int priority)
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/* Not implemented yet */
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/* Return the current thread's priority. */
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objc_thread_get_priority(void)
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/* Not implemented yet */
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return OBJC_THREAD_INTERACTIVE_PRIORITY;
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/* Yield our process time to another thread. */
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objc_thread_yield(void)
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#if !defined(__APPLE__)
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/* Not defined in darwin? */
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/* Terminate the current thread. */
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objc_thread_exit(void)
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/* Decrement our counter of the number of threads alive */
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objc_mutex_lock(__objc_runtime_mutex);
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__objc_runtime_threads_alive--;
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objc_mutex_unlock(__objc_runtime_mutex);
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/* exit the thread */
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pthread_exit(&__objc_thread_exit_status);
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/* Failed if we reached here */
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/* Returns an integer value which uniquely describes a thread. */
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pthread_t self = pthread_self();
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return *(objc_thread_t *)&self;
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/* Sets the thread's local storage pointer. */
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objc_thread_set_data(void *value)
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return pthread_setspecific(_objc_thread_storage, value);
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/* Returns the thread's local storage pointer. */
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objc_thread_get_data(void)
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return pthread_getspecific(_objc_thread_storage);
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/* Backend mutex functions */
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/* Allocate a mutex. */
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objc_mutex_allocate(void)
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/* Allocate the mutex structure */
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if (!(mutex = (objc_mutex_t)objc_malloc(sizeof(struct objc_mutex))))
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/* Call backend to create the mutex */
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if (pthread_mutex_init((pthread_mutex_t *)(&(mutex->backend)), NULL))
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/* Initialize mutex */
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/* Deallocate a mutex. */
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objc_mutex_deallocate(objc_mutex_t mutex)
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/* Acquire lock on mutex */
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depth = objc_mutex_lock(mutex);
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if (pthread_mutex_destroy((pthread_mutex_t *)(&(mutex->backend))))
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/* Free the mutex structure */
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/* Return last depth */
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/* Grab a lock on a mutex. */
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objc_mutex_lock(objc_mutex_t mutex)
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objc_thread_t thread_id;
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/* If we already own the lock then increment depth */
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thread_id = objc_thread_id();
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if (mutex->owner == thread_id)
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return ++mutex->depth;
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/* Call the backend to lock the mutex */
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status = pthread_mutex_lock((pthread_mutex_t *)(&(mutex->backend)));
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/* Successfully locked the thread */
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mutex->owner = thread_id;
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return mutex->depth = 1;
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/* Try to grab a lock on a mutex. */
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objc_mutex_trylock(objc_mutex_t mutex)
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objc_thread_t thread_id;
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/* If we already own the lock then increment depth */
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thread_id = objc_thread_id();
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if (mutex->owner == thread_id)
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return ++mutex->depth;
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/* Call the backend to try to lock the mutex */
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status = pthread_mutex_trylock((pthread_mutex_t *)(&(mutex->backend)));
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/* Successfully locked the thread */
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mutex->owner = thread_id;
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return mutex->depth = 1;
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/* Unlock the mutex */
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objc_mutex_unlock(objc_mutex_t mutex)
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objc_thread_t thread_id;
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/* If another thread owns the lock then abort */
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thread_id = objc_thread_id();
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if (mutex->owner != thread_id)
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/* Decrement depth and return */
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if (mutex->depth > 1)
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return --mutex->depth;
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/* Depth down to zero so we are no longer the owner */
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/* Have the backend unlock the mutex */
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return pthread_mutex_unlock((pthread_mutex_t *)(&(mutex->backend)));
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/* Backend condition mutex functions */
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/* Allocate a condition. */
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objc_condition_allocate(void)
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objc_condition_t condition;
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/* Allocate the condition mutex structure */
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(objc_condition_t)objc_malloc(sizeof(struct objc_condition))))
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/* Call the backend to create the condition mutex */
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if (pthread_cond_init((pthread_cond_t *)(&(condition->backend)), NULL))
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objc_free(condition);
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/* Deallocate a condition. */
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objc_condition_deallocate(objc_condition_t condition)
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/* Broadcast the condition */
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if (objc_condition_broadcast(condition))
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/* Call the backend to destroy */
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if (pthread_cond_destroy((pthread_cond_t *)(&(condition->backend))))
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/* Free the condition mutex structure */
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objc_free(condition);
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/* Wait on the condition */
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objc_condition_wait(objc_condition_t condition, objc_mutex_t mutex)
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objc_thread_t thread_id;
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/* Valid arguments? */
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if (!mutex || !condition)
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/* Make sure we are owner of mutex */
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thread_id = objc_thread_id();
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if (mutex->owner != thread_id)
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/* Cannot be locked more than once */
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if (mutex->depth > 1)
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/* Virtually unlock the mutex */
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mutex->owner = (objc_thread_t)NULL;
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/* Call the backend to wait */
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pthread_cond_wait((pthread_cond_t *)(&(condition->backend)),
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(pthread_mutex_t *)(&(mutex->backend)));
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/* Make ourselves owner of the mutex */
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mutex->owner = thread_id;
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/* Wake up all threads waiting on this condition. */
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objc_condition_broadcast(objc_condition_t condition)
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/* Valid condition mutex? */
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return pthread_cond_broadcast((pthread_cond_t *)(&(condition->backend)));
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/* Wake up one thread waiting on this condition. */
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objc_condition_signal(objc_condition_t condition)
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/* Valid condition mutex? */
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return pthread_cond_signal((pthread_cond_t *)(&(condition->backend)));
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/* Make the objc thread system aware that a thread which is managed
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(started, stopped) by external code could access objc facilities
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from now on. This is used when you are interfacing with some
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external non-objc-based environment/system - you must call
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objc_thread_add() before an alien thread makes any calls to
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Objective-C. Do not cause the _objc_became_multi_threaded hook to
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objc_thread_add(void)
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objc_mutex_lock(__objc_runtime_mutex);
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__objc_is_multi_threaded = 1;
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__objc_runtime_threads_alive++;
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objc_mutex_unlock(__objc_runtime_mutex);
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/* Make the objc thread system aware that a thread managed (started,
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stopped) by some external code will no longer access objc and thus
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can be forgotten by the objc thread system. Call
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objc_thread_remove() when your alien thread is done with making
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calls to Objective-C. */
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objc_thread_remove(void)
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objc_mutex_lock(__objc_runtime_mutex);
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__objc_runtime_threads_alive--;
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objc_mutex_unlock(__objc_runtime_mutex);
added
removed
Source/thr-pthread.m
