GstDataQueue

GstDataQueue — Threadsafe queueing object

Synopsis

#include <gst/base/gstdataqueue.h>

struct              GstDataQueue;
struct              GstDataQueueSize;
gboolean            (*GstDataQueueCheckFullFunction)    (GstDataQueue *queue,
                                                         guint visible,
                                                         guint bytes,
                                                         guint64 time,
                                                         gpointer checkdata);
struct              GstDataQueueItem;
void                (*GstDataQueueEmptyCallback)        (GstDataQueue *queue,
                                                         gpointer checkdata);
void                (*GstDataQueueFullCallback)         (GstDataQueue *queue,
                                                         gpointer checkdata);
GstDataQueue *      gst_data_queue_new                  (GstDataQueueCheckFullFunction checkfull,
                                                         GstDataQueueFullCallback fullcallback,
                                                         GstDataQueueEmptyCallback emptycallback,
                                                         gpointer checkdata);
gboolean            gst_data_queue_push                 (GstDataQueue *queue,
                                                         GstDataQueueItem *item);
gboolean            gst_data_queue_push_force           (GstDataQueue *queue,
                                                         GstDataQueueItem *item);
gboolean            gst_data_queue_pop                  (GstDataQueue *queue,
                                                         GstDataQueueItem **item);
void                gst_data_queue_flush                (GstDataQueue *queue);
void                gst_data_queue_set_flushing         (GstDataQueue *queue,
                                                         gboolean flushing);
gboolean            gst_data_queue_drop_head            (GstDataQueue *queue,
                                                         GType type);
gboolean            gst_data_queue_is_full              (GstDataQueue *queue);
gboolean            gst_data_queue_is_empty             (GstDataQueue *queue);
void                gst_data_queue_get_level            (GstDataQueue *queue,
                                                         GstDataQueueSize *level);
void                gst_data_queue_limits_changed       (GstDataQueue *queue);

Description

GstDataQueue is an object that handles threadsafe queueing of objects. It also provides size-related functionality. This object should be used for any GstElement that wishes to provide some sort of queueing functionality.

Details

struct GstDataQueue

struct GstDataQueue {
  GObject object;
};

Opaque GstDataQueue structure.

GObject object;

the parent structure

struct GstDataQueueSize

struct GstDataQueueSize {
  guint visible;
  guint bytes;
  guint64 time;
};

Structure describing the size of a queue.

guint visible;

number of buffers

guint bytes;

number of bytes

guint64 time;

amount of time

GstDataQueueCheckFullFunction ()

gboolean            (*GstDataQueueCheckFullFunction)    (GstDataQueue *queue,
                                                         guint visible,
                                                         guint bytes,
                                                         guint64 time,
                                                         gpointer checkdata);

The prototype of the function used to inform the queue that it should be considered as full.

queue :

a GstDataQueue.

visible :

The number of visible items currently in the queue.

bytes :

The amount of bytes currently in the queue.

time :

The accumulated duration of the items currently in the queue.

checkdata :

The gpointer registered when the GstDataQueue was created.

Returns :

TRUE if the queue should be considered full.

struct GstDataQueueItem

struct GstDataQueueItem {
  GstMiniObject *object;
  guint size;
  guint64 duration;
  gboolean visible;

  /* user supplied destroy function */
  GDestroyNotify destroy;
};

Structure used by GstDataQueue. You can supply a different structure, as long as the top of the structure is identical to this structure.

GstMiniObject *object;

the GstMiniObject to queue.

guint size;

the size in bytes of the miniobject.

guint64 duration;

the duration in GstClockTime of the miniobject. Can not be GST_CLOCK_TIME_NONE.

gboolean visible;

TRUE if object should be considered as a visible object.

GDestroyNotify destroy;

The GDestroyNotify function to use to free the GstDataQueueItem. This function should also drop the reference to object the owner of the GstDataQueueItem is assumed to hold.

GstDataQueueEmptyCallback ()

void                (*GstDataQueueEmptyCallback)        (GstDataQueue *queue,
                                                         gpointer checkdata);

GstDataQueueFullCallback ()

void                (*GstDataQueueFullCallback)         (GstDataQueue *queue,
                                                         gpointer checkdata);

gst_data_queue_new ()

GstDataQueue *      gst_data_queue_new                  (GstDataQueueCheckFullFunction checkfull,
                                                         GstDataQueueFullCallback fullcallback,
                                                         GstDataQueueEmptyCallback emptycallback,
                                                         gpointer checkdata);

Creates a new GstDataQueue. The difference with gst_data_queue_new is that it will not emit the 'full' and 'empty' signals, but instead calling directly fullcallback or emptycallback.

checkfull :

the callback used to tell if the element considers the queue full or not.

fullcallback :

the callback which will be called when the queue is considered full.

emptycallback :

the callback which will be called when the queue is considered empty.

checkdata :

a gpointer that will be given in the checkfull callback.

Returns :

a new GstDataQueue.

Since 1.2.0


gst_data_queue_push ()

gboolean            gst_data_queue_push                 (GstDataQueue *queue,
                                                         GstDataQueueItem *item);

Pushes a GstDataQueueItem (or a structure that begins with the same fields) on the queue. If the queue is full, the call will block until space is available, OR the queue is set to flushing state. MT safe.

Note that this function has slightly different semantics than gst_pad_push() and gst_pad_push_event(): this function only takes ownership of item and the GstMiniObject contained in item if the push was successful. If FALSE is returned, the caller is responsible for freeing item and its contents.

queue :

a GstDataQueue.

item :

a GstDataQueueItem.

Returns :

TRUE if the item was successfully pushed on the queue.

Since 1.2.0


gst_data_queue_push_force ()

gboolean            gst_data_queue_push_force           (GstDataQueue *queue,
                                                         GstDataQueueItem *item);

Pushes a GstDataQueueItem (or a structure that begins with the same fields) on the queue. It ignores if the queue is full or not and forces the item to be pushed anyway. MT safe.

Note that this function has slightly different semantics than gst_pad_push() and gst_pad_push_event(): this function only takes ownership of item and the GstMiniObject contained in item if the push was successful. If FALSE is returned, the caller is responsible for freeing item and its contents.

queue :

a GstDataQueue.

item :

a GstDataQueueItem.

Returns :

TRUE if the item was successfully pushed on the queue.

Since 1.2.0


gst_data_queue_pop ()

gboolean            gst_data_queue_pop                  (GstDataQueue *queue,
                                                         GstDataQueueItem **item);

Retrieves the first item available on the queue. If the queue is currently empty, the call will block until at least one item is available, OR the queue is set to the flushing state. MT safe.

queue :

a GstDataQueue.

item :

pointer to store the returned GstDataQueueItem.

Returns :

TRUE if an item was successfully retrieved from the queue.

Since 1.2.0


gst_data_queue_flush ()

void                gst_data_queue_flush                (GstDataQueue *queue);

Flushes all the contents of the queue. Any call to gst_data_queue_push and gst_data_queue_pop will be released. MT safe.

queue :

a GstDataQueue.

Since 1.2.0


gst_data_queue_set_flushing ()

void                gst_data_queue_set_flushing         (GstDataQueue *queue,
                                                         gboolean flushing);

Sets the queue to flushing state if flushing is TRUE. If set to flushing state, any incoming data on the queue will be discarded. Any call currently blocking on gst_data_queue_push or gst_data_queue_pop will return straight away with a return value of FALSE. While the queue is in flushing state, all calls to those two functions will return FALSE.

MT Safe.

queue :

a GstDataQueue.

flushing :

a gboolean stating if the queue will be flushing or not.

Since 1.2.0


gst_data_queue_drop_head ()

gboolean            gst_data_queue_drop_head            (GstDataQueue *queue,
                                                         GType type);

Pop and unref the head-most GstMiniObject with the given GType.

queue :

The GstDataQueue to drop an item from.

type :

The GType of the item to drop.

Returns :

TRUE if an element was removed.

Since 1.2.0


gst_data_queue_is_full ()

gboolean            gst_data_queue_is_full              (GstDataQueue *queue);

Queries if queue is full. This check will be done using the GstDataQueueCheckFullFunction registered with queue. MT safe.

queue :

a GstDataQueue.

Returns :

TRUE if queue is full.

Since 1.2.0


gst_data_queue_is_empty ()

gboolean            gst_data_queue_is_empty             (GstDataQueue *queue);

Queries if there are any items in the queue. MT safe.

queue :

a GstDataQueue.

Returns :

TRUE if queue is empty.

Since 1.2.0


gst_data_queue_get_level ()

void                gst_data_queue_get_level            (GstDataQueue *queue,
                                                         GstDataQueueSize *level);

Get the current level of the queue.

queue :

The GstDataQueue

level :

the location to store the result

Since 1.2.0


gst_data_queue_limits_changed ()

void                gst_data_queue_limits_changed       (GstDataQueue *queue);

Inform the queue that the limits for the fullness check have changed and that any blocking gst_data_queue_push() should be unblocked to recheck the limts.

queue :

The GstDataQueue

Since 1.2.0