gstreamer/gst/gstbus.c

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/* GStreamer
* Copyright (C) 2004 Wim Taymans <wim@fluendo.com>
*
* gstbus.c: GstBus subsystem
*
* 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 <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include "gst_private.h"
#include "gstinfo.h"
#include "gstbus.h"
enum
{
ARG_0,
};
static void gst_bus_class_init (GstBusClass * klass);
static void gst_bus_init (GstBus * bus);
static void gst_bus_dispose (GObject * object);
static void gst_bus_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec);
static void gst_bus_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec);
static GstObjectClass *parent_class = NULL;
/* static guint gst_bus_signals[LAST_SIGNAL] = { 0 }; */
GType
gst_bus_get_type (void)
{
static GType bus_type = 0;
if (!bus_type) {
static const GTypeInfo bus_info = {
sizeof (GstBusClass),
NULL,
NULL,
(GClassInitFunc) gst_bus_class_init,
NULL,
NULL,
sizeof (GstBus),
0,
(GInstanceInitFunc) gst_bus_init,
NULL
};
bus_type = g_type_register_static (GST_TYPE_OBJECT, "GstBus", &bus_info, 0);
}
return bus_type;
}
static void
gst_bus_class_init (GstBusClass * klass)
{
GObjectClass *gobject_class;
GstObjectClass *gstobject_class;
gobject_class = (GObjectClass *) klass;
gstobject_class = (GstObjectClass *) klass;
parent_class = g_type_class_ref (GST_TYPE_OBJECT);
if (!g_thread_supported ())
g_thread_init (NULL);
gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_bus_dispose);
gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_bus_set_property);
gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_bus_get_property);
}
static void
gst_bus_init (GstBus * bus)
{
bus->queue = g_queue_new ();
bus->queue_lock = g_mutex_new ();
if (socketpair (PF_UNIX, SOCK_STREAM, 0, bus->control_socket) < 0)
goto no_socketpair;
bus->io_channel = g_io_channel_unix_new (bus->control_socket[0]);
return;
/* errors */
no_socketpair:
{
g_warning ("cannot create io channel");
bus->io_channel = NULL;
}
}
static void
gst_bus_dispose (GObject * object)
{
GstBus *bus;
bus = GST_BUS (object);
if (bus->io_channel) {
g_io_channel_shutdown (bus->io_channel, TRUE, NULL);
g_io_channel_unref (bus->io_channel);
bus->io_channel = NULL;
}
close (bus->control_socket[0]);
close (bus->control_socket[1]);
if (bus->queue) {
g_mutex_lock (bus->queue_lock);
g_queue_free (bus->queue);
bus->queue = NULL;
g_mutex_unlock (bus->queue_lock);
g_mutex_free (bus->queue_lock);
bus->queue_lock = NULL;
}
G_OBJECT_CLASS (parent_class)->dispose (object);
}
static void
gst_bus_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstBus *bus;
bus = GST_BUS (object);
switch (prop_id) {
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_bus_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec)
{
GstBus *bus;
bus = GST_BUS (object);
switch (prop_id) {
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
GstBus *
gst_bus_new (void)
{
GstBus *result;
result = g_object_new (gst_bus_get_type (), NULL);
return result;
}
/**
* gst_bus_post:
* @bus: a #GstBus to post on
* @message: The #GstMessage to post
*
* Post a message on the given bus.
*
* Returns: TRUE if the message could be posted.
*
* MT safe.
*/
gboolean
gst_bus_post (GstBus * bus, GstMessage * message)
{
gchar c;
GstBusSyncReply reply = GST_BUS_PASS;
GstBusSyncHandler handler;
gpointer handler_data;
gboolean need_write = FALSE;
ssize_t write_ret = -1;
g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
g_return_val_if_fail (GST_IS_MESSAGE (message), FALSE);
//g_print ("posting message on bus, type %d\n", GST_MESSAGE_TYPE (message));
GST_DEBUG_OBJECT (bus, "posting message on bus");
GST_LOCK (bus);
handler = bus->sync_handler;
handler_data = bus->sync_handler_data;
GST_UNLOCK (bus);
/* first call the sync handler if it is installed */
if (handler) {
reply = handler (bus, message, handler_data);
}
/* now see what we should do with the message */
switch (reply) {
case GST_BUS_DROP:
/* drop the message */
break;
case GST_BUS_PASS:
/* pass the message to the async queue */
g_mutex_lock (bus->queue_lock);
if (g_queue_get_length (bus->queue) == 0)
need_write = TRUE;
g_queue_push_tail (bus->queue, message);
g_mutex_unlock (bus->queue_lock);
if (need_write) {
c = 'p';
errno = EAGAIN;
while (write_ret == -1) {
switch (errno) {
case EAGAIN:
case EINTR:
break;
default:
perror ("gst_bus_post: could not write to fd");
return FALSE;
}
write_ret = write (bus->control_socket[1], &c, 1);
}
}
break;
case GST_BUS_ASYNC:
{
/* async delivery, we need a mutex and a cond to block
* on */
GMutex *lock = g_mutex_new ();
GCond *cond = g_cond_new ();
GST_MESSAGE_COND (message) = cond;
GST_MESSAGE_GET_LOCK (message) = lock;
GST_DEBUG ("waiting for async delivery of message %p", message);
/* now we lock the message mutex, send the message to the async
* queue. When the message is handled by the app and destroyed,
* the cond will be signalled and we can continue */
g_mutex_lock (lock);
g_mutex_lock (bus->queue_lock);
if (g_queue_get_length (bus->queue) == 0)
need_write = TRUE;
g_queue_push_tail (bus->queue, message);
g_mutex_unlock (bus->queue_lock);
if (need_write) {
c = 'p';
errno = EAGAIN;
while (write_ret == -1) {
switch (errno) {
case EAGAIN:
case EINTR:
break;
default:
perror ("gst_bus_post: could not write to fd");
return FALSE;
}
write_ret = write (bus->control_socket[1], &c, 1);
}
}
/* now block till the message is freed */
g_cond_wait (cond, lock);
g_mutex_unlock (lock);
GST_DEBUG ("message %p delivered asynchronously", message);
g_mutex_free (lock);
g_cond_free (cond);
break;
}
}
return TRUE;
}
/**
* gst_bus_have_pending:
* @bus: a #GstBus to check
*
* Check if there are pending messages on the bus that should be
* handled.
*
* Returns: TRUE if there are messages on the bus to be handled.
*
* MT safe.
*/
gboolean
gst_bus_have_pending (GstBus * bus)
{
gint length;
g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
g_mutex_lock (bus->queue_lock);
length = g_queue_get_length (bus->queue);
g_mutex_unlock (bus->queue_lock);
return (length > 0);
}
/**
* gst_bus_pop:
* @bus: a #GstBus to pop
*
* Get a message from the bus.
*
* Returns: The #GstMessage that is on the bus, or NULL if the bus is empty.
*
* MT safe.
*/
GstMessage *
gst_bus_pop (GstBus * bus)
{
GstMessage *message;
gboolean needs_read = FALSE;
g_return_val_if_fail (GST_IS_BUS (bus), NULL);
g_mutex_lock (bus->queue_lock);
message = g_queue_pop_head (bus->queue);
if (message && g_queue_get_length (bus->queue) == 0)
needs_read = TRUE;
g_mutex_unlock (bus->queue_lock);
if (needs_read) {
gchar c;
ssize_t read_ret = -1;
/* the char in the fd is essentially just a way to wake us up. read it off so
we're not woken up again. */
errno = EAGAIN;
while (read_ret == -1) {
switch (errno) {
case EAGAIN:
case EINTR:
break;
default:
perror ("gst_bus_pop: could not read from fd");
return NULL;
}
read_ret = read (bus->control_socket[0], &c, 1);
}
}
return message;
}
/**
* gst_bus_peek:
* @bus: a #GstBus
*
* Peek the message on the top of the bus' queue. The bus maintains ownership of
* the message, and the message will remain on the bus' message queue.
*
* Returns: The #GstMessage that is on the bus, or NULL if the bus is empty.
*
* MT safe.
*/
GstMessage *
gst_bus_peek (GstBus * bus)
{
GstMessage *message;
g_return_val_if_fail (GST_IS_BUS (bus), NULL);
g_mutex_lock (bus->queue_lock);
message = g_queue_peek_head (bus->queue);
g_mutex_unlock (bus->queue_lock);
return message;
}
/**
* gst_bus_set_sync_handler:
* @bus: a #GstBus to install the handler on
* @func: The handler function to install
* @data: User data that will be sent to the handler function.
*
* Install a synchronous handler on the bus. The function will be called
* every time a new message is posted on the bus. Note that the function
* will be called in the same thread context as the posting object.
*/
void
gst_bus_set_sync_handler (GstBus * bus, GstBusSyncHandler func, gpointer data)
{
g_return_if_fail (GST_IS_BUS (bus));
GST_LOCK (bus);
bus->sync_handler = func;
bus->sync_handler_data = data;
GST_UNLOCK (bus);
}
/**
* gst_bus_create_watch:
* @bus: a #GstBus to create the watch for
*
* Create watch for this bus.
*
* Returns: A #GSource that can be added to a mainloop.
*/
GSource *
gst_bus_create_watch (GstBus * bus)
{
GSource *source;
g_return_val_if_fail (GST_IS_BUS (bus), NULL);
/* FIXME, we need to ref the bus and unref it when the source
* is destroyed */
source = g_io_create_watch (bus->io_channel, G_IO_IN);
return source;
}
typedef struct
{
GSource *source;
GstBus *bus;
gint priority;
GstBusHandler handler;
gpointer user_data;
GDestroyNotify notify;
} GstBusWatch;
static gboolean
bus_watch_callback (GIOChannel * channel, GIOCondition cond,
GstBusWatch * watch)
{
GstMessage *message;
gboolean needs_pop = TRUE;
g_return_val_if_fail (GST_IS_BUS (watch->bus), FALSE);
message = gst_bus_peek (watch->bus);
g_return_val_if_fail (message != NULL, TRUE);
if (watch->handler)
needs_pop = watch->handler (watch->bus, message, watch->user_data);
if (needs_pop)
gst_message_unref (gst_bus_pop (watch->bus));
return TRUE;
}
static void
bus_watch_destroy (GstBusWatch * watch)
{
if (watch->notify) {
watch->notify (watch->user_data);
}
gst_object_unref (GST_OBJECT_CAST (watch->bus));
g_free (watch);
}
/**
* gst_bus_add_watch_full:
* @bus: a #GstBus to create the watch for.
* @priority: The priority of the watch.
* @handler: A function to call when a message is received.
* @user_data: user data passed to @handler.
* @notify: the function to call when the source is removed.
*
* Adds the bus to the mainloop with the given priority. If the handler returns
* TRUE, the message will then be popped off the queue. When the handler is
* called, the message belongs to the caller; if you want to keep a copy of it,
* call gst_message_ref before leaving the handler.
*
* Returns: The event source id.
*
* MT safe.
*/
guint
gst_bus_add_watch_full (GstBus * bus, gint priority,
GstBusHandler handler, gpointer user_data, GDestroyNotify notify)
{
guint id;
GstBusWatch *watch;
g_return_val_if_fail (GST_IS_BUS (bus), 0);
watch = g_new (GstBusWatch, 1);
gst_object_ref (GST_OBJECT_CAST (bus));
watch->source = gst_bus_create_watch (bus);
watch->bus = bus;
watch->priority = priority;
watch->handler = handler;
watch->user_data = user_data;
watch->notify = notify;
if (priority != G_PRIORITY_DEFAULT)
g_source_set_priority (watch->source, priority);
g_source_set_callback (watch->source, (GSourceFunc) bus_watch_callback,
watch, (GDestroyNotify) bus_watch_destroy);
id = g_source_attach (watch->source, NULL);
g_source_unref (watch->source);
return id;
}
/**
* gst_bus_add_watch:
* @bus: a #GstBus to create the watch for
* @handler: A function to call when a message is received.
* @user_data: user data passed to @handler.
*
* Adds the bus to the mainloop with the default priority.
*
* Returns: The event source id.
*
* MT safe.
*/
guint
gst_bus_add_watch (GstBus * bus, GstBusHandler handler, gpointer user_data)
{
return gst_bus_add_watch_full (bus, G_PRIORITY_DEFAULT, handler, user_data,
NULL);
}
typedef struct
{
GMainLoop *loop;
guint timeout_id;
GstMessageType events;
GstMessageType revent;
} GstBusPollData;
static gboolean
poll_handler (GstBus * bus, GstMessage * message, GstBusPollData * poll_data)
{
if (GST_MESSAGE_TYPE (message) & poll_data->events) {
poll_data->revent = GST_MESSAGE_TYPE (message);
if (g_main_loop_is_running (poll_data->loop))
g_main_loop_quit (poll_data->loop);
/* keep the message on the queue */
return FALSE;
} else {
/* pop and unref the message */
return TRUE;
}
}
static gboolean
poll_timeout (GstBusPollData * poll_data)
{
poll_data->timeout_id = 0;
g_main_loop_quit (poll_data->loop);
/* returning FALSE will remove the source id */
return FALSE;
}
/**
* gst_bus_poll:
* @bus: a #GstBus
* @events: a mask of #GstMessageType, representing the set of message types to
* poll for.
* @timeout: the poll timeout, as a #GstClockTimeDiff, or -1 to poll indefinitely.
*
* Poll the bus for events. Will block while waiting for events to come. You can
* specify a maximum time to poll with the @timeout parameter. If @timeout is
* negative, this function will block indefinitely.
*
* Returns: The type of the message that was received, or GST_MESSAGE_UNKNOWN if
* the poll timed out. The message will remain in the bus queue; you will need
* to gst_bus_pop() it off before entering gst_bus_poll() again.
*/
GstMessageType
gst_bus_poll (GstBus * bus, GstMessageType events, GstClockTimeDiff timeout)
{
GstBusPollData *poll_data;
GstMessageType ret;
guint id;
poll_data = g_new0 (GstBusPollData, 1);
if (timeout >= 0)
poll_data->timeout_id = g_timeout_add (timeout / GST_MSECOND,
(GSourceFunc) poll_timeout, poll_data);
poll_data->loop = g_main_loop_new (NULL, FALSE);
poll_data->events = events;
poll_data->revent = GST_MESSAGE_UNKNOWN;
id = gst_bus_add_watch (bus, (GstBusHandler) poll_handler, poll_data);
g_main_loop_run (poll_data->loop);
g_source_remove (id);
ret = poll_data->revent;
if (poll_data->timeout_id)
g_source_remove (poll_data->timeout_id);
g_main_loop_unref (poll_data->loop);
g_free (poll_data);
return ret;
}