/* GStreamer * Copyright (C) 2003 Benjamin Otte * * gthread-cothreads.c: cothreads implemented via GThread for compatibility * They're probably slooooooow * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. */ #include /* the name of this cothreads */ #define COTHREADS_NAME "gthread" #define COTHREADS_NAME_CAPITAL "GThread" /** * Theory of operation: * Instead of using cothreads, GThreads and 1 mutex are used. * Every thread may only run if it holds the mutex. Otherwise it holds its own * cond which has to be signaled to wakeit up. */ /* define "cothread", "cothread_context" and "cothread_func" */ typedef void (*cothread_func) (int, char **); typedef struct _cothread cothread; typedef struct _cothread_context cothread_context; struct _cothread_context { GSList * cothreads; /* contains all threads but main */ cothread * main; cothread * current; GMutex * mutex; }; struct _cothread { GThread * thread; GCond * cond; cothread_func run; int argc; char ** argv; cothread * creator; gboolean die; cothread_context * context; }; /* define functions * Functions starting with "do_" are used by the scheduler. */ static void do_cothreads_init (void *unused); static cothread_context *do_cothread_context_init (void); static void do_cothread_context_destroy (cothread_context *context); static cothread * cothread_create (cothread_context *context, cothread_func func, int argc, char **argv); #define do_cothread_create(new_cothread, context, func, argc, argv) \ G_STMT_START{ \ new_cothread = cothread_create ((context), (func), argc, (char**) (argv)); \ }G_STMT_END static void do_cothread_switch (cothread *to); static void do_cothread_setfunc (cothread *thread, cothread_context *context, cothread_func func, int argc, char **argv); static void do_cothread_destroy (cothread *thread); #define do_cothread_lock(cothread) /* FIXME */ #define do_cothread_unlock(cothread) /* FIXME */ #define do_cothread_get_current(context) ((context)->current) #define do_cothread_get_main(context) ((context)->main) static void do_cothreads_init (void *unused) { if (!g_thread_supported ()) g_thread_init (NULL); } static cothread_context * do_cothread_context_init (void) { cothread_context *ret = g_new0 (cothread_context, 1); ret->main = g_new0 (cothread, 1); ret->main->thread = g_thread_self (); ret->main->cond = g_cond_new (); ret->main->die = FALSE; ret->main->context = ret; ret->mutex = g_mutex_new (); ret->cothreads = NULL; ret->current = ret->main; g_mutex_lock (ret->mutex); return ret; } static void do_cothread_context_destroy (cothread_context *context) { g_assert (g_thread_self() == context->main->thread); while (context->cothreads) { do_cothread_destroy ((cothread *) context->cothreads->data); } g_mutex_unlock (context->mutex); g_mutex_free (context->mutex); g_free (context); } static void die (cothread *to_die) { g_cond_free (to_die->cond); to_die->context->cothreads = g_slist_remove (to_die->context->cothreads, to_die); g_free (to_die); g_thread_exit (to_die); /* don't unlock the mutex here, the thread waiting for us to die is gonna take it */ } static gpointer run_new_thread (gpointer data) { cothread *self = (cothread *) data; g_mutex_lock (self->context->mutex); g_cond_signal (self->creator->cond); g_cond_wait (self->cond, self->context->mutex); if (self->die) die (self); while (TRUE) { self->run (self->argc, self->argv); /* compatibility */ do_cothread_switch (do_cothread_get_main (self->context)); } g_assert_not_reached (); return NULL; } static cothread * cothread_create (cothread_context *context, cothread_func func, int argc, char **argv) { cothread *ret; if ((ret = g_new (cothread, 1)) == NULL) { goto out1; } ret->cond = g_cond_new (); ret->run = func; ret->argc = argc; ret->argv = argv; ret->creator = do_cothread_get_current (context); ret->die = FALSE; ret->context = context; context->cothreads = g_slist_prepend (context->cothreads, ret); ret->thread = g_thread_create (run_new_thread, ret, TRUE, NULL); if (ret->thread == NULL) goto out2; g_cond_wait (do_cothread_get_current (context)->cond, context->mutex); return ret; out2: context->cothreads = g_slist_remove (context->cothreads, ret); g_free (ret); out1: return NULL; } static void do_cothread_switch (cothread *to) { cothread *self = do_cothread_get_current(to->context); if (self == to) { g_warning ("trying to switch to the same cothread, not allowed"); } else { self->context->current = to; g_cond_signal (to->cond); g_cond_wait (self->cond, self->context->mutex); if (self->die) die (self); } } static void do_cothread_setfunc (cothread *thread, cothread_context *context, cothread_func func, int argc, char **argv) { thread->run = func; thread->argc = argc; thread->argv = argv; } static void do_cothread_destroy (cothread *thread) { GThread *join; cothread_context *context; g_return_if_fail (thread != thread->context->main); g_return_if_fail (thread != thread->context->current); thread->die = TRUE; join = thread->thread; context = thread->context; g_cond_signal (thread->cond); g_mutex_unlock (thread->context->mutex); g_thread_join (join); /* the mutex was locked by the thread that we joined, no need to lock again */ } #define do_cothread_lock(cothread) /* FIXME */ #define do_cothread_unlock(cothread) /* FIXME */ #define do_cothread_get_current(context) ((context)->current) #define do_cothread_get_main(context) ((context)->main)