323 lines
12 KiB
C
323 lines
12 KiB
C
/* GNU Objective C Runtime Thread Interface for POSIX compliant threads
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Copyright (C) 1996, 1997 Free Software Foundation, Inc.
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Contributed by Galen C. Hunt (gchunt@cs.rochester.edu)
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Modified for Linux/Pthreads by Kai-Uwe Sattler (kus@iti.cs.uni-magdeburg.de)
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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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Foundation; either 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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details.
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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, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, 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 <objc/thr.h>
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#include "runtime.h"
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#include <pthread.h>
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/********
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* This structure represents a single mutual exclusion lock. Lock semantics
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* are detailed with the subsequent functions. We use whatever lock is
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* provided by the system. We augment it with depth and current owner id
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* fields to implement and re-entrant lock.
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*/
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struct objc_mutex
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{
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volatile objc_thread_t owner; /* Id of thread that owns. */
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volatile int depth; /* # of acquires. */
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pthread_mutex_t lock; /* pthread mutex. */
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};
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/*****************************************************************************
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* Static variables.
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*/
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static pthread_key_t __objc_thread_data_key; /* Data key for thread data.*/
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/********
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* Initialize the threads subsystem. Returns 0 if successful, or -1 if no
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* thread support is available.
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*/
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int
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__objc_init_thread_system(void)
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{
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if (pthread_key_create(&__objc_thread_data_key, NULL) == 0)
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return 0; /* Yes, return success. */
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return -1; /* Failed. */
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}
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int
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__objc_fini_thread_system(void)
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{
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return 0;
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}
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/********
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* Create a new thread of execution and return its id. Return NULL if fails.
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* The new thread starts in "func" with the given argument.
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*/
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objc_thread_t
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objc_thread_create(void (*func)(void *arg), void *arg)
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{
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objc_thread_t thread_id = NULL; /* Detached thread id. */
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pthread_t new_thread_handle; /* DCE thread handle. */
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objc_mutex_lock(__objc_runtime_mutex);
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if (pthread_create(&new_thread_handle, NULL,
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(void *)func, arg) == 0) {
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thread_id = (objc_thread_t) new_thread_handle;
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pthread_detach(new_thread_handle); /* Fully detach thread. */
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__objc_runtime_threads_alive++;
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}
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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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/********
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* Set the current thread's priority.
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*/
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int
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objc_thread_set_priority(int priority)
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{
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#if 0 /* no get/set priority in Linux pthreads */
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int sys_priority = 0;
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switch (priority) {
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case OBJC_THREAD_INTERACTIVE_PRIORITY:
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sys_priority = (PRI_FG_MIN_NP + PRI_FG_MAX_NP) / 2;
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break;
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default:
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case OBJC_THREAD_BACKGROUND_PRIORITY:
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sys_priority = (PRI_BG_MIN_NP + PRI_BG_MAX_NP) / 2;
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break;
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case OBJC_THREAD_LOW_PRIORITY:
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sys_priority = (PRI_BG_MIN_NP + PRI_BG_MAX_NP) / 2;
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break;
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}
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if (pthread_setprio(pthread_self(), sys_priority) >= 0)
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return 0; /* Changed priority. End. */
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#endif
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return -1; /* Failed. */
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}
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/********
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* Return the current thread's priority.
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*/
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int
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objc_thread_get_priority(void)
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{
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#if 0 /* no get/set priority in Linux pthreads */
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int sys_priority; /* DCE thread priority. */
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if ((sys_priority = pthread_getprio(pthread_self())) >= 0) {
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if (sys_priority >= PRI_FG_MIN_NP && sys_priority <= PRI_FG_MAX_NP)
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return OBJC_THREAD_INTERACTIVE_PRIORITY;
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if (sys_priority >= PRI_BG_MIN_NP && sys_priority <= PRI_BG_MAX_NP)
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return OBJC_THREAD_BACKGROUND_PRIORITY;
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return OBJC_THREAD_LOW_PRIORITY;
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}
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#endif
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return -1; /* Couldn't get priority. */
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}
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/********
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* Yield our process time to another thread. Any BUSY waiting that is done
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* by a thread should use this function to make sure that other threads can
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* make progress even on a lazy uniprocessor system.
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*/
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void
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objc_thread_yield(void)
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{
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pthread_yield(); /* Yield to equal thread. */
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}
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/********
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* Terminate the current tread. Doesn't return anything. Doesn't return.
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* Actually, if it failed returns -1.
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*/
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int
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objc_thread_exit(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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pthread_exit(&__objc_thread_exit_status); /* Terminate thread. */
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return -1;
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}
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/********
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* Returns an integer value which uniquely describes a thread. Must not be
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* -1 which is reserved as a marker for "no thread".
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*/
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objc_thread_t
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objc_thread_id(void)
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{
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pthread_t self = pthread_self();
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return (objc_thread_t) self; /* Return thread handle. */
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}
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/********
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* Sets the thread's local storage pointer. Returns 0 if successful or -1
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* if failed.
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*/
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int
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objc_thread_set_data(void *value)
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{
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if (pthread_setspecific(__objc_thread_data_key, (void *)value) == 0)
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return 0; /* Return thread data. */
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return -1;
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}
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/********
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* Returns the thread's local storage pointer. Returns NULL on failure.
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*/
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void *
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objc_thread_get_data(void)
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{
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return pthread_getspecific(__objc_thread_data_key);
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}
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/********
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* Allocate a mutex. Return the mutex pointer if successful or NULL if
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* the allocation fails for any reason.
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*/
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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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int err = 0;
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if (!(mutex = (objc_mutex_t)objc_malloc(sizeof(struct objc_mutex))))
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return NULL; /* Abort if malloc failed. */
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err = pthread_mutex_init(&mutex->lock, NULL);
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if (err != 0) { /* System init failed? */
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objc_free(mutex); /* Yes, free local memory. */
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return NULL; /* Abort. */
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}
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mutex->owner = NULL; /* No owner. */
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mutex->depth = 0; /* No locks. */
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return mutex; /* Return mutex handle. */
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}
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/********
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* Deallocate a mutex. Note that this includes an implicit mutex_lock to
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* insure that no one else is using the lock. It is legal to deallocate
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* a lock if we have a lock on it, but illegal to deallotcate a lock held
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* by anyone else.
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* Returns the number of locks on the thread. (1 for deallocate).
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*/
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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; /* # of locks on mutex. */
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if (!mutex) /* Is argument bad? */
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return -1; /* Yes, abort. */
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depth = objc_mutex_lock(mutex); /* Must have lock. */
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pthread_mutex_unlock(&mutex->lock); /* Must unlock system mutex.*/
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pthread_mutex_destroy(&mutex->lock); /* Free system mutex. */
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objc_free(mutex); /* Free memory. */
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return depth; /* Return last depth. */
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}
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/********
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* Grab a lock on a mutex. If this thread already has a lock on this mutex
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* then we increment the lock count. If another thread has a lock on the
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* mutex we block and wait for the thread to release the lock.
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* Returns the lock count on the mutex held by this thread.
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*/
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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; /* Cache our thread id. */
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if (!mutex) /* Is argument bad? */
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return -1; /* Yes, abort. */
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thread_id = objc_thread_id(); /* Get this thread's id. */
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if (mutex->owner == thread_id) /* Already own lock? */
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return ++mutex->depth; /* Yes, increment depth. */
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if (pthread_mutex_lock(&mutex->lock) != 0) /* Lock DCE system mutex. */
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return -1; /* Failed, abort. */
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mutex->owner = thread_id; /* Mark thread as owner. */
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return mutex->depth = 1; /* Increment depth to end. */
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}
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/********
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* Try to grab a lock on a mutex. If this thread already has a lock on
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* this mutex then we increment the lock count and return it. If another
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* thread has a lock on the mutex returns -1.
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*/
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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; /* Cache our thread id. */
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if (!mutex) /* Is argument bad? */
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return -1; /* Yes, abort. */
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thread_id = objc_thread_id(); /* Get this thread's id. */
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if (mutex->owner == thread_id) /* Already own lock? */
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return ++mutex->depth; /* Yes, increment depth. */
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if (pthread_mutex_trylock(&mutex->lock) != 1) /* Lock DCE system mutex. */
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return -1; /* Failed, abort. */
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mutex->owner = thread_id; /* Mark thread as owner. */
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return mutex->depth = 1; /* Increment depth to end. */
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}
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/********
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* Decrements the lock count on this mutex by one. If the lock count reaches
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* zero, release the lock on the mutex. Returns the lock count on the mutex.
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* It is an error to attempt to unlock a mutex which this thread doesn't hold
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* in which case return -1 and the mutex is unaffected.
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* Will also return -1 if the mutex free fails.
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*/
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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; /* Cache our thread id. */
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if (!mutex) /* Is argument bad? */
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return -1; /* Yes, abort. */
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thread_id = objc_thread_id(); /* Get this thread's id. */
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if (mutex->owner != thread_id) /* Does some else own lock? */
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return -1; /* Yes, abort. */
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if (mutex->depth > 1) /* Released last lock? */
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return --mutex->depth; /* No, Decrement depth, end.*/
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mutex->depth = 0; /* Yes, reset depth to 0. */
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mutex->owner = NULL; /* Set owner to "no thread".*/
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if (pthread_mutex_unlock(&mutex->lock) != 0) /* Unlock system mutex. */
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return -1; /* Failed, abort. */
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return 0; /* No, return success. */
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}
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