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threadmessage.h
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public License
6  * as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public License
15  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #ifndef AVUTIL_THREADMESSAGE_H
20 #define AVUTIL_THREADMESSAGE_H
21 
22 typedef struct AVThreadMessageQueue AVThreadMessageQueue;
23 
24 typedef enum AVThreadMessageFlags {
25 
26  /**
27  * Perform non-blocking operation.
28  * If this flag is set, send and recv operations are non-blocking and
29  * return AVERROR(EAGAIN) immediately if they can not proceed.
30  */
31  AV_THREAD_MESSAGE_NONBLOCK = 1,
32 
33 } AVThreadMessageFlags;
34 
35 /**
36  * Allocate a new message queue.
37  *
38  * @param mq pointer to the message queue
39  * @param nelem maximum number of elements in the queue
40  * @param elsize size of each element in the queue
41  * @return >=0 for success; <0 for error, in particular AVERROR(ENOSYS) if
42  * lavu was built without thread support
43  */
44 int av_thread_message_queue_alloc(AVThreadMessageQueue **mq,
45  unsigned nelem,
46  unsigned elsize);
47 
48 /**
49  * Free a message queue.
50  *
51  * The message queue must no longer be in use by another thread.
52  */
53 void av_thread_message_queue_free(AVThreadMessageQueue **mq);
54 
55 /**
56  * Send a message on the queue.
57  */
58 int av_thread_message_queue_send(AVThreadMessageQueue *mq,
59  void *msg,
60  unsigned flags);
61 
62 /**
63  * Receive a message from the queue.
64  */
65 int av_thread_message_queue_recv(AVThreadMessageQueue *mq,
66  void *msg,
67  unsigned flags);
68 
69 /**
70  * Set the sending error code.
71  *
72  * If the error code is set to non-zero, av_thread_message_queue_recv() will
73  * return it immediately when there are no longer available messages.
74  * Conventional values, such as AVERROR_EOF or AVERROR(EAGAIN), can be used
75  * to cause the receiving thread to stop or suspend its operation.
76  */
77 void av_thread_message_queue_set_err_send(AVThreadMessageQueue *mq,
78  int err);
79 
80 /**
81  * Set the receiving error code.
82  *
83  * If the error code is set to non-zero, av_thread_message_queue_send() will
84  * return it immediately. Conventional values, such as AVERROR_EOF or
85  * AVERROR(EAGAIN), can be used to cause the sending thread to stop or
86  * suspend its operation.
87  */
88 void av_thread_message_queue_set_err_recv(AVThreadMessageQueue *mq,
89  int err);
90 
91 #endif /* AVUTIL_THREADMESSAGE_H */
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