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threadmessage.c
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1 /*
2  * Copyright (c) 2014 Nicolas George
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public License
8  * as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public License
17  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "fifo.h"
22 #include "threadmessage.h"
23 #if HAVE_THREADS
24 #if HAVE_PTHREADS
25 #include <pthread.h>
26 #elif HAVE_W32THREADS
27 #include "compat/w32pthreads.h"
28 #elif HAVE_OS2THREADS
29 #include "compat/os2threads.h"
30 #else
31 #error "Unknown threads implementation"
32 #endif
33 #endif
34 
36 #if HAVE_THREADS
37  AVFifoBuffer *fifo;
38  pthread_mutex_t lock;
39  pthread_cond_t cond;
40  int err_send;
41  int err_recv;
42  unsigned elsize;
43 #else
44  int dummy;
45 #endif
46 };
47 
49  unsigned nelem,
50  unsigned elsize)
51 {
52 #if HAVE_THREADS
54  int ret = 0;
55 
56  if (nelem > INT_MAX / elsize)
57  return AVERROR(EINVAL);
58  if (!(rmq = av_mallocz(sizeof(*rmq))))
59  return AVERROR(ENOMEM);
60  if ((ret = pthread_mutex_init(&rmq->lock, NULL))) {
61  av_free(rmq);
62  return AVERROR(ret);
63  }
64  if ((ret = pthread_cond_init(&rmq->cond, NULL))) {
65  pthread_mutex_destroy(&rmq->lock);
66  av_free(rmq);
67  return AVERROR(ret);
68  }
69  if (!(rmq->fifo = av_fifo_alloc(elsize * nelem))) {
70  pthread_cond_destroy(&rmq->cond);
71  pthread_mutex_destroy(&rmq->lock);
72  av_free(rmq);
73  return AVERROR(ret);
74  }
75  rmq->elsize = elsize;
76  *mq = rmq;
77  return 0;
78 #else
79  *mq = NULL;
80  return AVERROR(ENOSYS);
81 #endif /* HAVE_THREADS */
82 }
83 
85 {
86 #if HAVE_THREADS
87  if (*mq) {
88  av_fifo_freep(&(*mq)->fifo);
89  pthread_cond_destroy(&(*mq)->cond);
90  pthread_mutex_destroy(&(*mq)->lock);
91  av_freep(mq);
92  }
93 #endif
94 }
95 
96 #if HAVE_THREADS
97 
98 static int av_thread_message_queue_send_locked(AVThreadMessageQueue *mq,
99  void *msg,
100  unsigned flags)
101 {
102  while (!mq->err_send && av_fifo_space(mq->fifo) < mq->elsize) {
103  if ((flags & AV_THREAD_MESSAGE_NONBLOCK))
104  return AVERROR(EAGAIN);
105  pthread_cond_wait(&mq->cond, &mq->lock);
106  }
107  if (mq->err_send)
108  return mq->err_send;
109  av_fifo_generic_write(mq->fifo, msg, mq->elsize, NULL);
110  pthread_cond_signal(&mq->cond);
111  return 0;
112 }
113 
114 static int av_thread_message_queue_recv_locked(AVThreadMessageQueue *mq,
115  void *msg,
116  unsigned flags)
117 {
118  while (!mq->err_recv && av_fifo_size(mq->fifo) < mq->elsize) {
119  if ((flags & AV_THREAD_MESSAGE_NONBLOCK))
120  return AVERROR(EAGAIN);
121  pthread_cond_wait(&mq->cond, &mq->lock);
122  }
123  if (av_fifo_size(mq->fifo) < mq->elsize)
124  return mq->err_recv;
125  av_fifo_generic_read(mq->fifo, msg, mq->elsize, NULL);
126  pthread_cond_signal(&mq->cond);
127  return 0;
128 }
129 
130 #endif /* HAVE_THREADS */
131 
133  void *msg,
134  unsigned flags)
135 {
136 #if HAVE_THREADS
137  int ret;
138 
139  pthread_mutex_lock(&mq->lock);
140  ret = av_thread_message_queue_send_locked(mq, msg, flags);
141  pthread_mutex_unlock(&mq->lock);
142  return ret;
143 #else
144  return AVERROR(ENOSYS);
145 #endif /* HAVE_THREADS */
146 }
147 
149  void *msg,
150  unsigned flags)
151 {
152 #if HAVE_THREADS
153  int ret;
154 
155  pthread_mutex_lock(&mq->lock);
156  ret = av_thread_message_queue_recv_locked(mq, msg, flags);
157  pthread_mutex_unlock(&mq->lock);
158  return ret;
159 #else
160  return AVERROR(ENOSYS);
161 #endif /* HAVE_THREADS */
162 }
163 
165  int err)
166 {
167 #if HAVE_THREADS
168  pthread_mutex_lock(&mq->lock);
169  mq->err_send = err;
170  pthread_cond_broadcast(&mq->cond);
171  pthread_mutex_unlock(&mq->lock);
172 #endif /* HAVE_THREADS */
173 }
174 
176  int err)
177 {
178 #if HAVE_THREADS
179  pthread_mutex_lock(&mq->lock);
180  mq->err_recv = err;
181  pthread_cond_broadcast(&mq->cond);
182  pthread_mutex_unlock(&mq->lock);
183 #endif /* HAVE_THREADS */
184 }