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544 lines
15 KiB
C
544 lines
15 KiB
C
/* GNU Objective C Runtime Thread Interface
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Copyright (C) 1996-2022 Free Software Foundation, Inc.
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Contributed by Galen C. Hunt (gchunt@cs.rochester.edu)
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This file is part of GCC.
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GCC 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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Foundation; either version 3, or (at your option) any later version.
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GCC 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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details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "objc-private/common.h"
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#include "objc-private/error.h"
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#define _LIBOBJC
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#include "config.h"
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#include "tconfig.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "defaults.h"
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#include "objc/thr.h"
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#include "objc/message.h" /* For objc_msg_lookup(). */
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#include "objc/runtime.h"
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#include "objc-private/module-abi-8.h"
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#include "objc-private/runtime.h"
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#include <gthr.h>
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#include <stdlib.h>
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/* Global exit status. */
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int __objc_thread_exit_status = 0;
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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
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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. The hook function is
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only called once, meaning only when the 2nd thread is spawned, not
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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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{
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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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return temp;
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}
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/* Private functions.
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These functions are utilized by the runtime, but they are not
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considered part of the public interface. */
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/* Initialize the threads subsystem. */
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int
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__objc_init_thread_system(void)
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{
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return __gthread_objc_init_thread_system ();
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}
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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 as the
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starting function for a new thread. */
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struct __objc_thread_start_state
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{
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SEL selector;
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id object;
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id argument;
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};
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static void __attribute__((noreturn))
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__objc_thread_detach_function (struct __objc_thread_start_state *istate)
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{
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/* Valid state? */
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if (istate)
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{
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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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objc_free (istate);
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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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{
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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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}
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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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else
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{
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/* FIXME: Should we abort here ? */
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_objc_abort ("objc_thread_detach called with bad selector.\n");
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}
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}
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else
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{
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/* FIXME: Should we abort here ? */
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_objc_abort ("objc_thread_detach called with NULL state.\n");
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}
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/* Exit the thread. */
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objc_thread_exit ();
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/* Make sure compiler detects no return. */
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__builtin_trap ();
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}
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/* Public functions.
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These functions constitute the public interface to the Objective-C
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thread and mutex functionality. */
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/* Detach a new thread of execution and return its id. Returns NULL
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if fails. Thread is started by sending message with selector to
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object. Message takes a single argument. */
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objc_thread_t
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objc_thread_detach (SEL selector, id object, id argument)
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{
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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 *)objc_malloc
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(sizeof (*istate))))
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return NULL;
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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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/* Lock access. */
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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 = __gthread_objc_thread_detach ((void *)__objc_thread_detach_function,
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istate)) == NULL)
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{
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/* Failed! */
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objc_mutex_unlock (__objc_runtime_mutex);
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objc_free (istate);
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return NULL;
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}
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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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return thread_id;
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}
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/* Set the current thread's priority. */
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int
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objc_thread_set_priority (int priority)
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{
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return __gthread_objc_thread_set_priority (priority);
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}
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/* Return the current thread's priority. */
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int
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objc_thread_get_priority (void)
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{
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return __gthread_objc_thread_get_priority ();
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}
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/* Yield our process time to another thread. Any BUSY waiting that is
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done by a thread should use this function to make sure that other
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threads can make progress even on a lazy uniprocessor system. */
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void
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objc_thread_yield (void)
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{
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__gthread_objc_thread_yield ();
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}
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/* Terminate the current tread. Doesn't return. Actually, if it
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failed returns -1. */
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int
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objc_thread_exit (void)
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{
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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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/* Call the backend to terminate the thread. */
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return __gthread_objc_thread_exit ();
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}
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/* Returns an integer value which uniquely describes a thread. Must
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not be NULL which is reserved as a marker for "no thread". */
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objc_thread_t
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objc_thread_id (void)
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{
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return __gthread_objc_thread_id ();
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}
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/* Sets the thread's local storage pointer. Returns 0 if successful
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or -1 if failed. */
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int
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objc_thread_set_data (void *value)
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{
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return __gthread_objc_thread_set_data (value);
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}
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/* Returns the thread's local storage pointer. Returns NULL on
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failure. */
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void *
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objc_thread_get_data (void)
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{
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return __gthread_objc_thread_get_data ();
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}
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/* Public mutex functions */
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/* Allocate a mutex. Return the mutex pointer if successful or NULL
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if the allocation failed for any reason. */
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objc_mutex_t
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objc_mutex_allocate (void)
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{
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objc_mutex_t mutex;
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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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return NULL;
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/* Call backend to create the mutex. */
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if (__gthread_objc_mutex_allocate (mutex))
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{
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/* Failed! */
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objc_free (mutex);
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return NULL;
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}
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/* Initialize mutex. */
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mutex->owner = NULL;
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mutex->depth = 0;
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return mutex;
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}
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/* Deallocate a mutex. Note that this includes an implicit mutex_lock
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to insure that no one else is using the lock. It is legal to
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deallocate a lock if we have a lock on it, but illegal to
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deallocate a lock held by anyone else. Returns the number of locks
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on the thread. (1 for deallocate). */
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int
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objc_mutex_deallocate (objc_mutex_t mutex)
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{
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int depth;
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/* Valid mutex? */
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if (! mutex)
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return -1;
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/* Acquire lock on mutex. */
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depth = objc_mutex_lock (mutex);
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/* Call backend to destroy mutex. */
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if (__gthread_objc_mutex_deallocate (mutex))
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return -1;
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/* Free the mutex structure. */
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objc_free (mutex);
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/* Return last depth. */
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return depth;
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}
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/* Grab a lock on a mutex. If this thread already has a lock on this
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mutex then we increment the lock count. If another thread has a
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lock on the mutex we block and wait for the thread to release the
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lock. Returns the lock count on the mutex held by this thread. */
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int
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objc_mutex_lock (objc_mutex_t mutex)
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{
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objc_thread_t thread_id;
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int status;
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/* Valid mutex? */
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if (! mutex)
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return -1;
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/* If we already own the lock then increment depth. */
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thread_id = __gthread_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 = __gthread_objc_mutex_lock (mutex);
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/* Failed? */
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if (status)
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return status;
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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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}
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/* Try to grab a lock on a mutex. If this thread already has a lock
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on this mutex then we increment the lock count and return it. If
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another thread has a lock on the mutex returns -1. */
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int
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objc_mutex_trylock (objc_mutex_t mutex)
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{
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objc_thread_t thread_id;
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int status;
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/* Valid mutex? */
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if (! mutex)
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return -1;
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/* If we already own the lock then increment depth. */
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thread_id = __gthread_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 = __gthread_objc_mutex_trylock (mutex);
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/* Failed? */
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if (status)
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return status;
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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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}
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/* Unlocks the mutex by one level. Decrements the lock count on this
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mutex by one. If the lock count reaches zero, release the lock on
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the mutex. Returns the lock count on the mutex. It is an error to
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attempt to unlock a mutex which this thread doesn't hold in which
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case return -1 and the mutex is unaffected. */
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int
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objc_mutex_unlock (objc_mutex_t mutex)
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{
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objc_thread_t thread_id;
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int status;
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/* Valid mutex? */
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if (! mutex)
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return -1;
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/* If another thread owns the lock then abort. */
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thread_id = __gthread_objc_thread_id ();
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if (mutex->owner != thread_id)
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return -1;
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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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mutex->depth = 0;
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mutex->owner = NULL;
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/* Have the backend unlock the mutex. */
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status = __gthread_objc_mutex_unlock (mutex);
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/* Failed? */
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if (status)
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return status;
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return 0;
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}
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/* Public condition mutex functions */
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/* Allocate a condition. Return the condition pointer if successful
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or NULL if the allocation failed for any reason. */
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objc_condition_t
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objc_condition_allocate (void)
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{
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objc_condition_t condition;
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/* Allocate the condition mutex structure. */
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if (! (condition =
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(objc_condition_t) objc_malloc (sizeof (struct objc_condition))))
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return NULL;
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/* Call the backend to create the condition mutex. */
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if (__gthread_objc_condition_allocate (condition))
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{
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/* Failed! */
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objc_free (condition);
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return NULL;
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}
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/* Success! */
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return condition;
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}
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/* Deallocate a condition. Note that this includes an implicit
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condition_broadcast to insure that waiting threads have the
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opportunity to wake. It is legal to dealloc a condition only if no
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other thread is/will be using it. Here we do NOT check for other
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threads waiting but just wake them up. */
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int
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objc_condition_deallocate (objc_condition_t condition)
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{
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/* Broadcast the condition. */
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if (objc_condition_broadcast (condition))
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return -1;
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/* Call the backend to destroy. */
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if (__gthread_objc_condition_deallocate (condition))
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return -1;
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/* Free the condition mutex structure. */
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objc_free (condition);
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return 0;
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}
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/* Wait on the condition unlocking the mutex until
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objc_condition_signal () or objc_condition_broadcast () are called
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for the same condition. The given mutex *must* have the depth set
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to 1 so that it can be unlocked here, so that someone else can lock
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it and signal/broadcast the condition. The mutex is used to lock
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access to the shared data that make up the "condition"
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predicate. */
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int
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objc_condition_wait (objc_condition_t condition, objc_mutex_t mutex)
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{
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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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return -1;
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/* Make sure we are owner of mutex. */
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thread_id = __gthread_objc_thread_id ();
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if (mutex->owner != thread_id)
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return -1;
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/* Cannot be locked more than once. */
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if (mutex->depth > 1)
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return -1;
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/* Virtually unlock the mutex. */
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mutex->depth = 0;
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mutex->owner = (objc_thread_t)NULL;
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/* Call the backend to wait. */
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__gthread_objc_condition_wait (condition, mutex);
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/* Make ourselves owner of the mutex. */
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mutex->owner = thread_id;
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mutex->depth = 1;
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return 0;
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}
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/* Wake up all threads waiting on this condition. It is recommended
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that the called would lock the same mutex as the threads in
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objc_condition_wait before changing the "condition predicate" and
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make this call and unlock it right away after this call. */
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int
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objc_condition_broadcast (objc_condition_t condition)
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{
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/* Valid condition mutex? */
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if (! condition)
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return -1;
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return __gthread_objc_condition_broadcast (condition);
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}
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/* Wake up one thread waiting on this condition. It is recommended
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that the called would lock the same mutex as the threads in
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objc_condition_wait before changing the "condition predicate" and
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make this call and unlock it right away after this call. */
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int
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objc_condition_signal (objc_condition_t condition)
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{
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/* Valid condition mutex? */
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if (! condition)
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return -1;
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return __gthread_objc_condition_signal (condition);
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}
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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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be executed. */
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void
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objc_thread_add (void)
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{
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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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}
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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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void
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objc_thread_remove (void)
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{
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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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}
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