/* GStreamer * Copyright (C) 1999,2000 Erik Walthinsen * 2000 Wim Taymans * 2003 Benjamin Otte * * gstthread.c: Threaded container object * * 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 "gst_private.h" #include "gstthread.h" #include "gstmarshal.h" #include "gstscheduler.h" #include "gstinfo.h" #define GST_CAT_DEFAULT GST_CAT_THREAD #define STACK_SIZE 0x200000 static GstElementDetails gst_thread_details = GST_ELEMENT_DETAILS ("Threaded container", "Generic/Bin", "Container that creates/manages a thread", "Erik Walthinsen , " "Benjamin Otte dispose = gst_thread_dispose; #ifndef GST_DISABLE_LOADSAVE gstobject_class->save_thyself = GST_DEBUG_FUNCPTR (gst_thread_save_thyself); gstobject_class->restore_thyself = GST_DEBUG_FUNCPTR (gst_thread_restore_thyself); #endif gstelement_class->change_state = GST_DEBUG_FUNCPTR (gst_thread_change_state); gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_thread_set_property); gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_thread_get_property); gstbin_class->child_state_change = GST_DEBUG_FUNCPTR (gst_thread_child_state_change); } static void gst_thread_init (GTypeInstance * instance, gpointer g_class) { GstScheduler *scheduler; GstThread *thread = GST_THREAD (instance); GST_DEBUG ("initializing thread"); /* threads are managing bins and iterate themselves */ /* CR1: the GstBin code checks these flags */ GST_FLAG_SET (thread, GST_BIN_FLAG_MANAGER); GST_FLAG_SET (thread, GST_BIN_SELF_SCHEDULABLE); scheduler = gst_scheduler_factory_make (NULL, GST_ELEMENT (thread)); g_assert (scheduler); thread->lock = g_mutex_new (); thread->cond = g_cond_new (); thread->iterate_lock = g_mutex_new (); thread->thread_id = (GThread *) NULL; /* set in NULL -> READY */ thread->priority = G_THREAD_PRIORITY_NORMAL; } static void gst_thread_dispose (GObject * object) { GstThread *thread = GST_THREAD (object); GST_CAT_DEBUG (GST_CAT_REFCOUNTING, "GstThread: dispose"); /* if we get here, the thread is really stopped as it has released * the last refcount to the thread object, so we can safely free the * mutex and cond vars */ G_OBJECT_CLASS (parent_class)->dispose (object); g_assert (GST_STATE (thread) == GST_STATE_NULL); GST_CAT_DEBUG (GST_CAT_REFCOUNTING, "GstThread: dispose, freeing locks"); g_mutex_free (thread->lock); g_cond_free (thread->cond); g_mutex_free (thread->iterate_lock); gst_object_replace ((GstObject **) & GST_ELEMENT_SCHED (thread), NULL); } /** * gst_thread_set_priority: * @thread: the thread to change * @priority: the new priority for the thread * * change the thread's priority */ void gst_thread_set_priority (GstThread * thread, GThreadPriority priority) { g_return_if_fail (GST_IS_THREAD (thread)); thread->priority = priority; } static void gst_thread_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) { GstThread *thread; thread = GST_THREAD (object); switch (prop_id) { case ARG_PRIORITY: thread->priority = g_value_get_enum (value); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } static void gst_thread_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) { GstThread *thread; thread = GST_THREAD (object); switch (prop_id) { case ARG_PRIORITY: g_value_set_enum (value, thread->priority); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } /** * gst_thread_new: * @name: the name of the thread * * Create a new thread with the given name. * * Returns: The new thread */ GstElement * gst_thread_new (const gchar * name) { return gst_element_factory_make ("thread", name); } /** * gst_thread_get_current: * * Gets the current GstThread. * * Returns: The current GstThread or NULL if you are not running inside a * #GstThread. */ GstThread * gst_thread_get_current (void) { return (GstThread *) g_private_get (gst_thread_current); } static inline void gst_thread_release_children_locks (GstThread * thread) { GstRealPad *peer = NULL; GstElement *peerelement; GList *elements = (GList *) gst_bin_get_list (GST_BIN (thread)); while (elements) { GstElement *element = GST_ELEMENT (elements->data); GList *pads; g_assert (element); GST_DEBUG_OBJECT (thread, "waking element \"%s\"", GST_ELEMENT_NAME (element)); elements = g_list_next (elements); if (!gst_element_release_locks (element)) g_warning ("element %s could not release locks", GST_ELEMENT_NAME (element)); pads = GST_ELEMENT_PADS (element); while (pads) { if (GST_PAD_PEER (pads->data)) { peer = GST_REAL_PAD (GST_PAD_PEER (pads->data)); pads = g_list_next (pads); } else { pads = g_list_next (pads); continue; } if (!peer) continue; peerelement = GST_PAD_PARENT (peer); if (!peerelement) continue; /* FIXME: deal with case where there's no peer */ if (GST_ELEMENT_SCHED (peerelement) != GST_ELEMENT_SCHED (thread)) { GST_LOG_OBJECT (thread, "element \"%s\" has pad cross sched boundary", GST_ELEMENT_NAME (element)); GST_LOG_OBJECT (thread, "waking element \"%s\"", GST_ELEMENT_NAME (peerelement)); if (!gst_element_release_locks (peerelement)) g_warning ("element %s could not release locks", GST_ELEMENT_NAME (peerelement)); } } } } /* sync the main thread, if there is one and makes sure that the thread * is not spinning and in the waiting state. We can only do this if * this function is not called from the thread itself. * * This function should be called with the thread lock held. */ static void gst_thread_sync (GstThread * thread, gboolean is_self) { if (thread->thread_id == NULL) return; /* need to stop spinning in any case */ GST_FLAG_UNSET (thread, GST_THREAD_STATE_SPINNING); if (is_self) { /* we're trying to sync ourself. Not much we can do here but hope * that the thread will stop spinning and end up in the waiting * state */ GST_DEBUG_OBJECT (thread, "syncing itself"); } else { GST_DEBUG_OBJECT (thread, "syncing thread, grabbing lock"); /* another thread is trying to sync us. The strategy is to * repeadetly unlock the element locks until the thread is * blocking in the waiting state. We use a timeout because * unlocking all of the children at the same time is not * atomic and might fail. */ while (!GST_FLAG_IS_SET (thread, GST_THREAD_STATE_WAITING)) { GTimeVal tv; GST_LOG_OBJECT (thread, "syncing thread..."); /* release child locks */ gst_thread_release_children_locks (thread); g_get_current_time (&tv); g_time_val_add (&tv, 1000); /* wait a millisecond to sync the thread */ GST_DEBUG_OBJECT (thread, "wait"); g_cond_timed_wait (thread->cond, thread->lock, &tv); } GST_LOG_OBJECT (thread, "caught thread"); /* at this point we should be waiting */ g_assert (GST_FLAG_IS_SET (thread, GST_THREAD_STATE_WAITING)); } g_assert (!GST_FLAG_IS_SET (thread, GST_THREAD_STATE_SPINNING)); } static GstElementStateReturn gst_thread_change_state (GstElement * element) { GstThread *thread; GstElementStateReturn ret; gint transition; gboolean is_self; g_return_val_if_fail (GST_IS_THREAD (element), GST_STATE_FAILURE); GST_DEBUG_OBJECT (element, "changing state from %s to %s", gst_element_state_get_name (GST_STATE (element)), gst_element_state_get_name (GST_STATE_PENDING (element))); thread = GST_THREAD (element); /* boolean to check if we called the state change in the same thread as * the iterate thread */ is_self = (thread == gst_thread_get_current ()); GST_LOG_OBJECT (thread, "grabbing lock"); g_mutex_lock (thread->lock); gst_thread_sync (thread, is_self); /* no iteration is allowed during this state change because an iteration * can cause another state change conflicting with this one */ /* do not try to grab the lock if this method is called from the * same thread as the iterate thread, the lock might be held and we * might deadlock */ if (!is_self) g_mutex_lock (thread->iterate_lock); transition = GST_STATE_TRANSITION (element); switch (transition) { case GST_STATE_NULL_TO_READY: /* create the thread */ GST_FLAG_UNSET (thread, GST_THREAD_STATE_REAPING); GST_LOG_OBJECT (element, "grabbing lock"); thread->thread_id = g_thread_create_full (gst_thread_main_loop, thread, STACK_SIZE, FALSE, TRUE, thread->priority, NULL); if (!thread->thread_id) { GST_ERROR_OBJECT (element, "g_thread_create_full failed"); goto error_out; } GST_LOG_OBJECT (element, "GThread created"); /* wait for it to 'spin up' */ g_cond_wait (thread->cond, thread->lock); break; case GST_STATE_READY_TO_PAUSED: break; case GST_STATE_PAUSED_TO_PLAYING: { /* FIXME: recurse into sub-bins */ GList *elements = (GList *) gst_bin_get_list (GST_BIN (thread)); while (elements) { gst_element_enable_threadsafe_properties ((GstElement *) elements-> data); elements = g_list_next (elements); } /* reset self to spinning */ GST_FLAG_SET (thread, GST_THREAD_STATE_SPINNING); break; } case GST_STATE_PLAYING_TO_PAUSED: { GList *elements; GST_FLAG_UNSET (thread, GST_THREAD_STATE_SPINNING); elements = (GList *) gst_bin_get_list (GST_BIN (thread)); while (elements) { gst_element_disable_threadsafe_properties ((GstElement *) elements-> data); elements = g_list_next (elements); } break; } case GST_STATE_PAUSED_TO_READY: GST_FLAG_UNSET (thread, GST_THREAD_STATE_SPINNING); break; case GST_STATE_READY_TO_NULL: /* we can't join the threads here, because this could have been triggered by ourself (ouch) */ GST_LOG_OBJECT (thread, "destroying GThread %p", thread->thread_id); GST_FLAG_SET (thread, GST_THREAD_STATE_REAPING); GST_FLAG_UNSET (thread, GST_THREAD_STATE_SPINNING); /* thread was already gone */ if (thread->thread_id != NULL) { thread->thread_id = NULL; if (is_self) { GST_LOG_OBJECT (thread, "Thread %s is destroying itself. Returning to mainloop ASAP!", GST_ELEMENT_NAME (thread)); break; } else { /* now wait for the thread to destroy itself */ GST_DEBUG_OBJECT (thread, "signal"); g_cond_signal (thread->cond); GST_DEBUG_OBJECT (thread, "wait"); g_cond_wait (thread->cond, thread->lock); GST_DEBUG_OBJECT (thread, "done"); /* it should be dead now */ } } break; default: break; } GST_LOG_OBJECT (thread, "unlocking lock"); g_mutex_unlock (thread->lock); if (GST_ELEMENT_CLASS (parent_class)->change_state) { ret = GST_ELEMENT_CLASS (parent_class)->change_state (GST_ELEMENT (thread)); } else { ret = GST_STATE_SUCCESS; } g_mutex_lock (thread->lock); if (GST_STATE (thread) == GST_STATE_PLAYING && GST_FLAG_IS_SET (thread, GST_THREAD_STATE_WAITING)) { GST_FLAG_SET (thread, GST_THREAD_STATE_SPINNING); if (!is_self) { g_cond_signal (thread->cond); } } g_mutex_unlock (thread->lock); if (!is_self) g_mutex_unlock (thread->iterate_lock); return ret; error_out: GST_CAT_DEBUG (GST_CAT_STATES, "changing state from %s to %s failed for %s", gst_element_state_get_name (GST_STATE (element)), gst_element_state_get_name (GST_STATE_PENDING (element)), GST_ELEMENT_NAME (element)); g_mutex_unlock (thread->lock); if (!is_self) g_mutex_unlock (thread->iterate_lock); return GST_STATE_FAILURE; } /* When a child changes its state the thread might have to start. * * When we are in the thread context we set the spinning flag. * When we are not in the thread context, we grab the lock. The * thread can then only be in the waiting or spinning state. If it's * waiting we signal it to start. If it was spinning, we let it spin. */ static void gst_thread_child_state_change (GstBin * bin, GstElementState oldstate, GstElementState newstate, GstElement * element) { GstThread *thread = GST_THREAD (bin); gboolean is_self; GstThread *current; current = gst_thread_get_current (); is_self = (current == thread); GST_LOG_OBJECT (bin, "(from thread %s) child %s changed state from %s to %s", current ? GST_ELEMENT_NAME (current) : "(none)", GST_ELEMENT_NAME (element), gst_element_state_get_name (oldstate), gst_element_state_get_name (newstate)); if (parent_class->child_state_change) parent_class->child_state_change (bin, oldstate, newstate, element); /* if we're changing from playing to paused, kids will one-by-one go * to paused while we're playing, which is bad if we execute the code * below. We should only do that when a child explicitely changed * state outside our own context. */ if (GST_FLAG_IS_SET (bin, GST_BIN_STATE_LOCKED)) return; /* see if we have to wake up the thread now. */ if (is_self) { GST_LOG_OBJECT (element, "we are in the thread context"); /* we are the thread, set the spinning flag so that we start spinning * next time */ if (newstate == GST_STATE_PLAYING) { GST_FLAG_SET (thread, GST_THREAD_STATE_SPINNING); } } else { g_mutex_lock (thread->lock); /* thread is now spinning or waiting after grabbing the lock */ if (newstate == GST_STATE_PLAYING) { if (!GST_FLAG_IS_SET (thread, GST_THREAD_STATE_WAITING)) { /* its spinning, that's not really a problem, it will * continue to do so */ GST_LOG_OBJECT (element, "thread is playing"); } else { /* waiting, set spinning flag and trigger restart. */ GST_LOG_OBJECT (element, "signal playing"); GST_FLAG_SET (thread, GST_THREAD_STATE_SPINNING); g_cond_signal (GST_THREAD (bin)->cond); } } g_mutex_unlock (thread->lock); } GST_LOG_OBJECT (element, "done child state change"); } /** * gst_thread_main_loop: * @arg: the thread to start * * The main loop of the thread. The thread will iterate * while the state is GST_THREAD_STATE_SPINNING. */ static void * gst_thread_main_loop (void *arg) { GstThread *thread = NULL; GstElement *element = NULL; GstScheduler *sched; thread = GST_THREAD (arg); GST_LOG_OBJECT (element, "grabbing lock"); g_mutex_lock (thread->lock); element = GST_ELEMENT (arg); GST_LOG_OBJECT (thread, "Started main loop"); /* initialize gst_thread_current */ g_private_set (gst_thread_current, thread); /* set up the element's scheduler */ gst_scheduler_setup (GST_ELEMENT_SCHED (thread)); GST_FLAG_UNSET (thread, GST_THREAD_STATE_REAPING); GST_FLAG_UNSET (thread, GST_THREAD_STATE_WAITING); /* signals the startup of the thread */ GST_LOG_OBJECT (element, "signal"); g_cond_signal (thread->cond); GST_LOG_OBJECT (element, "unlocking lock"); gst_object_ref (GST_OBJECT (thread)); /* as long as we're not dying we can continue */ while (!(GST_FLAG_IS_SET (thread, GST_THREAD_STATE_REAPING))) { /* in the playing state we need to do something special */ if (GST_STATE (thread) == GST_STATE_PLAYING) { GST_LOG_OBJECT (thread, "starting to iterate"); /* continue iteration while spinning */ while (GST_FLAG_IS_SET (thread, GST_THREAD_STATE_SPINNING)) { gboolean status; g_mutex_unlock (thread->lock); g_mutex_lock (thread->iterate_lock); status = gst_bin_iterate (GST_BIN (thread)); g_mutex_unlock (thread->iterate_lock); g_mutex_lock (thread->lock); if (!status) { GST_DEBUG_OBJECT (thread, "iterate returned false"); if (GST_STATE (thread) != GST_STATE_PLAYING) { GST_DEBUG_OBJECT (thread, "stopping spinning as state is not playing"); GST_FLAG_UNSET (thread, GST_THREAD_STATE_SPINNING); } } /* if we hold the last refcount, the app unreffed the * thread and we should stop ASAP */ if (G_OBJECT (thread)->ref_count == 1) { GST_DEBUG_OBJECT (thread, "reaping as refcount is only 1"); GST_FLAG_SET (thread, GST_THREAD_STATE_REAPING); GST_FLAG_UNSET (thread, GST_THREAD_STATE_SPINNING); } } } /* do not try to sync when we are REAPING */ if (!(GST_FLAG_IS_SET (thread, GST_THREAD_STATE_REAPING))) { /* sync section */ GST_LOG_OBJECT (thread, "entering sync"); GST_DEBUG_OBJECT (thread, "signal"); g_cond_signal (thread->cond); GST_DEBUG_OBJECT (thread, "wait"); GST_FLAG_UNSET (thread, GST_THREAD_STATE_SPINNING); GST_FLAG_SET (thread, GST_THREAD_STATE_WAITING); g_cond_wait (thread->cond, thread->lock); GST_FLAG_UNSET (thread, GST_THREAD_STATE_WAITING); GST_LOG_OBJECT (thread, "wait done"); } } GST_LOG_OBJECT (thread, "unlocking lock"); thread->thread_id = NULL; g_mutex_unlock (thread->lock); /* we need to destroy the scheduler here because it might have * mapped it's stack into the threads stack space */ sched = GST_ELEMENT_SCHED (thread); if (sched) gst_scheduler_reset (sched); g_signal_emit (G_OBJECT (thread), gst_thread_signals[SHUTDOWN], 0); /* signal - we are out */ GST_LOG_OBJECT (thread, "Thread %p exits main loop", g_thread_self ()); g_cond_signal (thread->cond); gst_object_unref (GST_OBJECT (thread)); /* don't assume the GstThread object exists anymore now */ return NULL; } #ifndef GST_DISABLE_LOADSAVE static xmlNodePtr gst_thread_save_thyself (GstObject * object, xmlNodePtr self) { if (GST_OBJECT_CLASS (parent_class)->save_thyself) GST_OBJECT_CLASS (parent_class)->save_thyself (object, self); return NULL; } static void gst_thread_restore_thyself (GstObject * object, xmlNodePtr self) { GST_LOG_OBJECT (object, "restoring"); if (GST_OBJECT_CLASS (parent_class)->restore_thyself) GST_OBJECT_CLASS (parent_class)->restore_thyself (object, self); } #endif /* GST_DISABLE_LOADSAVE */