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An object that can be waited on and asked for asynchronous values. In much the same way as promise/futures in js/java/etc A callback can be installed for when the promise changes state. Original idea by Jan Schmidt <jan@centricular.com> With contributions from Nirbheek Chauhan <nirbheek@centricular.com> Mathieu Duponchelle <mathieu@centricular.com> https://bugzilla.gnome.org/show_bug.cgi?id=789843
119 lines
3.5 KiB
C
119 lines
3.5 KiB
C
/* GStreamer
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* Copyright (C) 2017 Matthew Waters <matthew@centricular.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __GST_PROMISE_H__
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#define __GST_PROMISE_H__
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#include <gst/gst.h>
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G_BEGIN_DECLS
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GST_EXPORT
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GType gst_promise_get_type(void);
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#define GST_TYPE_PROMISE (gst_promise_get_type())
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#define GST_PROMISE(obj) ((GstPromise *) obj)
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typedef struct _GstPromise GstPromise;
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/**
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* GstPromiseResult:
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* @GST_PROMISE_RESULT_PENDING: Initial state. Waiting for transition to any
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* other state.
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* @GST_PROMISE_RESULT_INTERRUPTED: Interrupted by the consumer as it doesn't
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* want the value anymore.
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* @GST_PROMISE_RESULT_REPLIED: A producer marked a reply
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* @GST_PROMISE_RESULT_EXPIRED: The promise expired (the carrying object
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* lost all refs) and the promise will never be fulfilled.
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*
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* The result of a #GstPromise
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*/
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typedef enum
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{
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GST_PROMISE_RESULT_PENDING,
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GST_PROMISE_RESULT_INTERRUPTED,
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GST_PROMISE_RESULT_REPLIED,
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GST_PROMISE_RESULT_EXPIRED,
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} GstPromiseResult;
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/**
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* GstPromiseChangeFunc:
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* @promise: a #GstPromise
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* @user_data: (closure): user data
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*/
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typedef void (*GstPromiseChangeFunc) (GstPromise * promise, gpointer user_data);
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/**
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* GstPromise:
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* @parent: parent #GstMiniObject
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*/
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struct _GstPromise
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{
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GstMiniObject parent;
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};
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GST_EXPORT
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GstPromise * gst_promise_new (void);
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GST_EXPORT
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GstPromise * gst_promise_new_with_change_func (GstPromiseChangeFunc func,
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gpointer user_data,
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GDestroyNotify notify);
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GST_EXPORT
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GstPromiseResult gst_promise_wait (GstPromise * promise);
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GST_EXPORT
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void gst_promise_reply (GstPromise * promise,
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GstStructure * s);
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GST_EXPORT
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void gst_promise_interrupt (GstPromise * promise);
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GST_EXPORT
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void gst_promise_expire (GstPromise * promise);
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GST_EXPORT
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const GstStructure * gst_promise_get_reply (GstPromise * promise);
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/**
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* gst_promise_ref:
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* @promise: a #GstPromise.
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*
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* Increases the refcount of the given @promise by one.
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*
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* Returns: (transfer full): @promise
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*/
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static inline GstPromise *
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gst_promise_ref (GstPromise * promise)
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{
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return (GstPromise *) gst_mini_object_ref (GST_MINI_OBJECT_CAST (promise));
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}
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/**
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* gst_promise_unref:
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* @promise: (transfer full): a #GstPromise.
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*
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* Decreases the refcount of the promise. If the refcount reaches 0, the
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* promise will be freed.
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*/
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static inline void
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gst_promise_unref (GstPromise * promise)
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{
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gst_mini_object_unref (GST_MINI_OBJECT_CAST (promise));
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}
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G_END_DECLS
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#endif /* __GST_PROMISE_H__ */
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