/**
* gst_buffer_pool_acquire_buffer:
* @pool: a #GstBufferPool
* @buffer: (out): a location for a #GstBuffer
* @params: (transfer none) (allow-none) parameters.
*
* Acquire a buffer from @pool. @buffer should point to a memory location that
* can hold a pointer to the new buffer.
*
* @params can be NULL or contain optional parameters to influence the allocation.
*
* Returns: a #GstFlowReturn such as GST_FLOW_FLUSHING when the pool is
* inactive.
*/
GstFlowReturn
gst_buffer_pool_acquire_buffer (GstBufferPool * pool, GstBuffer ** buffer,
GstBufferPoolAcquireParams * params)
{
GstBufferPoolClass *pclass;
GstFlowReturn result;
g_return_val_if_fail (GST_IS_BUFFER_POOL (pool), GST_FLOW_ERROR);
g_return_val_if_fail (buffer != NULL, GST_FLOW_ERROR);
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
/* assume we'll have one more outstanding buffer we need to do that so
* that concurrent set_active doesn't clear the buffers */
g_atomic_int_inc (&pool->priv->outstanding);
if (G_LIKELY (pclass->acquire_buffer))
result = pclass->acquire_buffer (pool, buffer, params);
else
result = GST_FLOW_NOT_SUPPORTED;
if (G_LIKELY (result == GST_FLOW_OK)) {
/* all buffers from the pool point to the pool and have the refcount of the
* pool incremented */
(*buffer)->pool = gst_object_ref (pool);
} else {
dec_outstanding (pool);
}
return result;
}
/* the default implementation for preallocating the buffers
* in the pool */
static gboolean
default_start (GstBufferPool * pool)
{
guint i;
GstBufferPoolPrivate *priv = pool->priv;
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
/* we need to prealloc buffers */
for (i = 0; i < priv->min_buffers; i++) {
GstBuffer *buffer;
if (do_alloc_buffer (pool, &buffer, NULL) != GST_FLOW_OK)
goto alloc_failed;
/* release to the queue, we call the vmethod directly, we don't need to do
* the other refcount handling right now. */
if (G_LIKELY (pclass->release_buffer))
pclass->release_buffer (pool, buffer);
}
return TRUE;
/* ERRORS */
alloc_failed:
{
GST_WARNING_OBJECT (pool, "failed to allocate buffer");
return FALSE;
}
}
/**
* gst_buffer_pool_release_buffer:
* @pool: a #GstBufferPool
* @buffer: (transfer full): a #GstBuffer
*
* Release @buffer to @pool. @buffer should have previously been allocated from
* @pool with gst_buffer_pool_acquire_buffer().
*
* This function is usually called automatically when the last ref on @buffer
* disappears.
*/
void
gst_buffer_pool_release_buffer (GstBufferPool * pool, GstBuffer * buffer)
{
GstBufferPoolClass *pclass;
g_return_if_fail (GST_IS_BUFFER_POOL (pool));
g_return_if_fail (buffer != NULL);
/* check that the buffer is ours, all buffers returned to the pool have the
* pool member set to NULL and the pool refcount decreased */
if (!g_atomic_pointer_compare_and_exchange (&buffer->pool, pool, NULL))
return;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
/* reset the buffer when needed */
if (G_LIKELY (pclass->reset_buffer))
pclass->reset_buffer (pool, buffer);
if (G_LIKELY (pclass->release_buffer))
pclass->release_buffer (pool, buffer);
dec_outstanding (pool);
/* decrease the refcount that the buffer had to us */
gst_object_unref (pool);
}
/* must be called with the lock */
static void
do_set_flushing (GstBufferPool * pool, gboolean flushing)
{
GstBufferPoolPrivate *priv = pool->priv;
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
if (GST_BUFFER_POOL_IS_FLUSHING (pool) == flushing)
return;
if (flushing) {
g_atomic_int_set (&pool->flushing, 1);
gst_poll_write_control (priv->poll);
if (pclass->flush_start)
pclass->flush_start (pool);
} else {
if (pclass->flush_stop)
pclass->flush_stop (pool);
gst_poll_read_control (priv->poll);
g_atomic_int_set (&pool->flushing, 0);
}
}
/**
* gst_buffer_pool_set_config:
* @pool: a #GstBufferPool
* @config: (transfer full): a #GstStructure
*
* Set the configuration of the pool. The pool must be inactive and all buffers
* allocated form this pool must be returned or else this function will do
* nothing and return FALSE.
*
* @config is a #GstStructure that contains the configuration parameters for
* the pool. A default and mandatory set of parameters can be configured with
* gst_buffer_pool_config_set_params(), gst_buffer_pool_config_set_allocator()
* and gst_buffer_pool_config_add_option().
*
* If the parameters in @config can not be set exactly, this function returns
* FALSE and will try to update as much state as possible. The new state can
* then be retrieved and refined with gst_buffer_pool_get_config().
*
* This function takes ownership of @config.
*
* Returns: TRUE when the configuration could be set.
*/
gboolean
gst_buffer_pool_set_config (GstBufferPool * pool, GstStructure * config)
{
gboolean result;
GstBufferPoolClass *pclass;
GstBufferPoolPrivate *priv;
g_return_val_if_fail (GST_IS_BUFFER_POOL (pool), FALSE);
g_return_val_if_fail (config != NULL, FALSE);
priv = pool->priv;
GST_BUFFER_POOL_LOCK (pool);
/* can't change the settings when active */
if (priv->active)
goto was_active;
/* we can't change when outstanding buffers */
if (g_atomic_int_get (&priv->outstanding) != 0)
goto have_outstanding;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
/* set the new config */
if (G_LIKELY (pclass->set_config))
result = pclass->set_config (pool, config);
else
result = FALSE;
if (result) {
if (priv->config)
gst_structure_free (priv->config);
priv->config = config;
/* now we are configured */
priv->configured = TRUE;
} else {
gst_structure_free (config);
}
GST_BUFFER_POOL_UNLOCK (pool);
return result;
/* ERRORS */
was_active:
{
gst_structure_free (config);
GST_WARNING_OBJECT (pool, "can't change config, we are active");
GST_BUFFER_POOL_UNLOCK (pool);
return FALSE;
}
have_outstanding:
{
gst_structure_free (config);
GST_WARNING_OBJECT (pool, "can't change config, have outstanding buffers");
GST_BUFFER_POOL_UNLOCK (pool);
return FALSE;
}
}
static GstFlowReturn
do_alloc_buffer (GstBufferPool * pool, GstBuffer ** buffer,
GstBufferPoolAcquireParams * params)
{
GstBufferPoolPrivate *priv = pool->priv;
GstFlowReturn result;
gint cur_buffers, max_buffers;
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
if (G_UNLIKELY (!pclass->alloc_buffer))
goto no_function;
max_buffers = priv->max_buffers;
/* increment the allocation counter */
cur_buffers = g_atomic_int_add (&priv->cur_buffers, 1);
if (max_buffers && cur_buffers >= max_buffers)
goto max_reached;
result = pclass->alloc_buffer (pool, buffer, params);
if (G_UNLIKELY (result != GST_FLOW_OK))
goto alloc_failed;
/* lock all metadata and mark as pooled, we want this to remain on
* the buffer and we want to remove any other metadata that gets added
* later */
gst_buffer_foreach_meta (*buffer, mark_meta_pooled, pool);
/* un-tag memory, this is how we expect the buffer when it is
* released again */
GST_BUFFER_FLAG_UNSET (*buffer, GST_BUFFER_FLAG_TAG_MEMORY);
GST_LOG_OBJECT (pool, "allocated buffer %d/%d, %p", cur_buffers,
max_buffers, *buffer);
return result;
/* ERRORS */
no_function:
{
GST_ERROR_OBJECT (pool, "no alloc function");
return GST_FLOW_NOT_SUPPORTED;
}
max_reached:
{
GST_DEBUG_OBJECT (pool, "max buffers reached");
g_atomic_int_add (&priv->cur_buffers, -1);
return GST_FLOW_EOS;
}
alloc_failed:
{
GST_WARNING_OBJECT (pool, "alloc function failed");
g_atomic_int_add (&priv->cur_buffers, -1);
return result;
}
}
static GstFlowReturn
do_alloc_buffer (GstBufferPool * pool, GstBuffer ** buffer,
GstBufferPoolAcquireParams * params)
{
GstBufferPoolPrivate *priv = pool->priv;
GstFlowReturn result;
gint cur_buffers, max_buffers;
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
if (G_UNLIKELY (!pclass->alloc_buffer))
goto no_function;
max_buffers = priv->max_buffers;
/* increment the allocation counter */
cur_buffers = g_atomic_int_add (&priv->cur_buffers, 1);
if (max_buffers && cur_buffers >= max_buffers)
goto max_reached;
result = pclass->alloc_buffer (pool, buffer, params);
if (G_UNLIKELY (result != GST_FLOW_OK))
goto alloc_failed;
gst_buffer_foreach_meta (*buffer, mark_meta_pooled, pool);
GST_LOG_OBJECT (pool, "allocated buffer %d/%d, %p", cur_buffers,
max_buffers, buffer);
return result;
/* ERRORS */
no_function:
{
GST_ERROR_OBJECT (pool, "no alloc function");
return GST_FLOW_NOT_SUPPORTED;
}
max_reached:
{
GST_DEBUG_OBJECT (pool, "max buffers reached");
g_atomic_int_add (&priv->cur_buffers, -1);
return GST_FLOW_EOS;
}
alloc_failed:
{
GST_WARNING_OBJECT (pool, "alloc function failed");
g_atomic_int_add (&priv->cur_buffers, -1);
return result;
}
}
static void
do_free_buffer (GstBufferPool * pool, GstBuffer * buffer)
{
GstBufferPoolPrivate *priv;
GstBufferPoolClass *pclass;
priv = pool->priv;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
g_atomic_int_add (&priv->cur_buffers, -1);
GST_LOG_OBJECT (pool, "freeing buffer %p (%u left)", buffer,
priv->cur_buffers);
if (G_LIKELY (pclass->free_buffer))
pclass->free_buffer (pool, buffer);
}
/* must be called with the lock */
static gboolean
do_stop (GstBufferPool * pool)
{
GstBufferPoolPrivate *priv = pool->priv;
if (priv->started) {
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
GST_LOG_OBJECT (pool, "stopping");
if (G_LIKELY (pclass->stop)) {
if (!pclass->stop (pool))
return FALSE;
}
priv->started = FALSE;
}
return TRUE;
}
/* must be called with the lock */
static gboolean
default_stop (GstBufferPool * pool)
{
GstBufferPoolPrivate *priv = pool->priv;
GstBuffer *buffer;
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
/* clear the pool */
while ((buffer = gst_atomic_queue_pop (priv->queue))) {
GST_LOG_OBJECT (pool, "freeing %p", buffer);
gst_poll_read_control (priv->poll);
if (G_LIKELY (pclass->free_buffer))
pclass->free_buffer (pool, buffer);
}
priv->cur_buffers = 0;
return TRUE;
}
/* must be called with the lock */
static gboolean
do_start (GstBufferPool * pool)
{
GstBufferPoolPrivate *priv = pool->priv;
if (!priv->started) {
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
GST_LOG_OBJECT (pool, "starting");
/* start the pool, subclasses should allocate buffers and put them
* in the queue */
if (G_LIKELY (pclass->start)) {
if (!pclass->start (pool))
return FALSE;
}
priv->started = TRUE;
}
return TRUE;
}
/* must be called with the lock */
static void
do_set_flushing (GstBufferPool * pool, gboolean flushing)
{
GstBufferPoolPrivate *priv = pool->priv;
GstBufferPoolClass *pclass;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
if (GST_BUFFER_POOL_IS_FLUSHING (pool) == flushing)
return;
if (flushing) {
g_atomic_int_set (&pool->flushing, 1);
/* Write the flush token to wake up any waiters */
gst_poll_write_control (priv->poll);
if (pclass->flush_start)
pclass->flush_start (pool);
} else {
if (pclass->flush_stop)
pclass->flush_stop (pool);
while (!gst_poll_read_control (priv->poll)) {
if (errno == EWOULDBLOCK) {
/* This should not really happen unless flushing and unflushing
* happens on different threads. Let's wait a bit to get back flush
* token from the thread that was setting it to flushing */
g_thread_yield ();
continue;
} else {
/* Critical error but GstPoll already complained */
break;
}
}
g_atomic_int_set (&pool->flushing, 0);
}
}
/**
* gst_buffer_pool_set_config:
* @pool: a #GstBufferPool
* @config: (transfer full): a #GstStructure
*
* Set the configuration of the pool. If the pool is already configured, and
* the configuration haven't change, this function will return %TRUE. If the
* pool is active, this method will return %FALSE and active configuration
* will remain. Buffers allocated form this pool must be returned or else this
* function will do nothing and return %FALSE.
*
* @config is a #GstStructure that contains the configuration parameters for
* the pool. A default and mandatory set of parameters can be configured with
* gst_buffer_pool_config_set_params(), gst_buffer_pool_config_set_allocator()
* and gst_buffer_pool_config_add_option().
*
* If the parameters in @config can not be set exactly, this function returns
* %FALSE and will try to update as much state as possible. The new state can
* then be retrieved and refined with gst_buffer_pool_get_config().
*
* This function takes ownership of @config.
*
* Returns: %TRUE when the configuration could be set.
*/
gboolean
gst_buffer_pool_set_config (GstBufferPool * pool, GstStructure * config)
{
gboolean result;
GstBufferPoolClass *pclass;
GstBufferPoolPrivate *priv;
g_return_val_if_fail (GST_IS_BUFFER_POOL (pool), FALSE);
g_return_val_if_fail (config != NULL, FALSE);
priv = pool->priv;
GST_BUFFER_POOL_LOCK (pool);
/* nothing to do if config is unchanged */
if (priv->configured && gst_structure_is_equal (config, priv->config))
goto config_unchanged;
/* can't change the settings when active */
if (priv->active)
goto was_active;
/* we can't change when outstanding buffers */
if (g_atomic_int_get (&priv->outstanding) != 0)
goto have_outstanding;
pclass = GST_BUFFER_POOL_GET_CLASS (pool);
/* set the new config */
if (G_LIKELY (pclass->set_config))
result = pclass->set_config (pool, config);
else
result = FALSE;
/* save the config regardless of the result so user can read back the
* modified config and evaluate if the changes are acceptable */
if (priv->config)
gst_structure_free (priv->config);
priv->config = config;
if (result) {
/* now we are configured */
priv->configured = TRUE;
}
GST_BUFFER_POOL_UNLOCK (pool);
return result;
config_unchanged:
{
gst_structure_free (config);
GST_BUFFER_POOL_UNLOCK (pool);
return TRUE;
}
/* ERRORS */
was_active:
{
gst_structure_free (config);
GST_INFO_OBJECT (pool, "can't change config, we are active");
GST_BUFFER_POOL_UNLOCK (pool);
return FALSE;
}
have_outstanding:
{
gst_structure_free (config);
GST_WARNING_OBJECT (pool, "can't change config, have outstanding buffers");
GST_BUFFER_POOL_UNLOCK (pool);
return FALSE;
}
}
