|  |  |  | GStreamer 0.10 Core Reference Manual |  | 
|---|---|---|---|---|
#include <gst/gst.h>
                    GstTask;
void                (*GstTaskFunction)                  (void *data);
enum                GstTaskState;
#define             GST_TASK_BROADCAST                  (task)
#define             GST_TASK_GET_COND                   (task)
#define             GST_TASK_GET_LOCK                   (task)
#define             GST_TASK_SIGNAL                     (task)
#define             GST_TASK_STATE                      (task)
#define             GST_TASK_WAIT                       (task)
void                gst_task_cleanup_all                (void);
GstTask*            gst_task_create                     (GstTaskFunction func,
                                                         gpointer data);
GstTaskState        gst_task_get_state                  (GstTask *task);
gboolean            gst_task_join                       (GstTask *task);
gboolean            gst_task_pause                      (GstTask *task);
void                gst_task_set_lock                   (GstTask *task,
                                                         GStaticRecMutex *mutex);
gboolean            gst_task_start                      (GstTask *task);
gboolean            gst_task_stop                       (GstTask *task);
GstTask is used by GstElement and GstPad to provide the data passing threads in a GstPipeline.
A GstPad will typically start a GstTask to push or pull data to/from the peer pads. Most source elements start a GstTask to push data. In some cases a demuxer element can start a GstTask to pull data from a peer element. This is typically done when the demuxer can perform random access on the upstream peer element for improved performance.
Although convenience functions exist on GstPad to start/pause/stop tasks, it might sometimes be needed to create a GstTask manually if it is not related to a GstPad.
Before the GstTask can be run, it needs a GStaticRecMutex that can be set with
gst_task_set_lock().
The task can be started, paused and stopped with gst_task_start(), gst_task_pause()
and gst_task_stop() respectively.
A GstTask will repeatedly call the GstTaskFunction with the user data
that was provided when creating the task with gst_task_create(). Before calling
the function it will acquire the provided lock.
Stopping a task with gst_task_stop() will not immediately make sure the task is
not running anymore. Use gst_task_join() to make sure the task is completely
stopped and the thread is stopped.
After creating a GstTask, use gst_object_unref() to free its resources. This can
only be done it the task is not running anymore.
Last reviewed on 2006-02-13 (0.10.4)
typedef struct {
  GstTaskState     state;
  GCond 	  *cond;
  GStaticRecMutex *lock;
  GstTaskFunction  func;
  gpointer 	   data;
  gboolean	   running;
} GstTask;
The GstTask object.
| GstTaskState  | the state of the task | 
| GCond * | used to pause/resume the task | 
| GStaticRecMutex * | The lock taken when iterating the task function | 
| GstTaskFunction  | the function executed by this task | 
| gpointer  | data passed to the task function | 
| gboolean  | a flag indicating that the task is running | 
void (*GstTaskFunction) (void *data);
A function that will repeatedly be called in the thread created by a GstTask.
| 
 | user data passed to the function | 
typedef enum {
  GST_TASK_STARTED,
  GST_TASK_STOPPED,
  GST_TASK_PAUSED
} GstTaskState;
The different states a task can be in
#define GST_TASK_BROADCAST(task) g_cond_breadcast(GST_TASK_GET_COND (task))
Send a broadcast signal to all waiting task conds
| 
 | Task to broadcast | 
#define GST_TASK_GET_COND(task) (GST_TASK_CAST(task)->cond)
Get access to the cond of the task.
| 
 | Task to get the cond of | 
#define GST_TASK_GET_LOCK(task) (GST_TASK_CAST(task)->lock)
Get access to the task lock.
| 
 | Task to get the lock of | 
#define GST_TASK_SIGNAL(task) g_cond_signal(GST_TASK_GET_COND (task))
Signal the task cond
| 
 | Task to signal | 
#define GST_TASK_STATE(task) (GST_TASK_CAST(task)->state)
Get access to the state of the task.
| 
 | Task to get the state of | 
#define GST_TASK_WAIT(task) g_cond_wait(GST_TASK_GET_COND (task), GST_OBJECT_GET_LOCK (task))
Wait for the task cond to be signalled
| 
 | Task to wait for | 
void gst_task_cleanup_all (void);
Wait for all tasks to be stopped. This is mainly used internally to ensure proper cleanup of internal data structures in test suites.
MT safe.
GstTask* gst_task_create (GstTaskFunction func, gpointer data);
Create a new Task that will repeatedly call the provided func
with data as a parameter. Typically the task will run in
a new thread.
The function cannot be changed after the task has been created. You must create a new GstTask to change the function.
| 
 | The GstTaskFunction to use | 
| 
 | User data to pass to func | 
| Returns : | A new GstTask. MT safe. | 
GstTaskState gst_task_get_state (GstTask *task);
Get the current state of the task.
| 
 | The GstTask to query | 
| Returns : | The GstTaskState of the task MT safe. | 
gboolean gst_task_join (GstTask *task);
Joins task. After this call, it is safe to unref the task
and clean up the lock set with gst_task_set_lock().
The task will automatically be stopped with this call.
This function cannot be called from within a task function as this would cause a deadlock. The function will detect this and print a g_warning.
| 
 | The GstTask to join | 
| Returns : | TRUEif the task could be joined.
MT safe. | 
gboolean gst_task_pause (GstTask *task);
Pauses task. This method can also be called on a task in the
stopped state, in which case a thread will be started and will remain
in the paused state. This function does not wait for the task to complete
the paused state.
| 
 | The GstTask to pause | 
| Returns : | TRUEif the task could be paused.
MT safe. | 
void gst_task_set_lock (GstTask *task, GStaticRecMutex *mutex);
Set the mutex used by the task. The mutex will be acquired before calling the GstTaskFunction.
This function has to be called before calling gst_task_pause() or
gst_task_start().
MT safe.
| 
 | The GstTask to use | 
| 
 | The GMutex to use | 
gboolean gst_task_start (GstTask *task);
Starts task. The task must have a lock associated with it using
gst_task_set_lock() or this function will return FALSE.
| 
 | The GstTask to start | 
| Returns : | TRUEif the task could be started.
MT safe. | 
gboolean gst_task_stop (GstTask *task);
Stops task. This method merely schedules the task to stop and
will not wait for the task to have completely stopped. Use
gst_task_join() to stop and wait for completion.
| 
 | The GstTask to stop | 
| Returns : | TRUEif the task could be stopped.
MT safe. |