threadmessage.h (3910B)
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_send() will 73 * return it immediately. Conventional values, such as AVERROR_EOF or 74 * AVERROR(EAGAIN), can be used to cause the sending thread to stop or 75 * 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_recv() will 84 * return it immediately when there are no longer available messages. 85 * Conventional values, such as AVERROR_EOF or AVERROR(EAGAIN), can be used 86 * to cause the receiving thread to stop or suspend its operation. 87 */ 88 void av_thread_message_queue_set_err_recv(AVThreadMessageQueue *mq, 89 int err); 90 91 /** 92 * Set the optional free message callback function which will be called if an 93 * operation is removing messages from the queue. 94 */ 95 void av_thread_message_queue_set_free_func(AVThreadMessageQueue *mq, 96 void (*free_func)(void *msg)); 97 98 /** 99 * Return the current number of messages in the queue. 100 * 101 * @return the current number of messages or AVERROR(ENOSYS) if lavu was built 102 * without thread support 103 */ 104 int av_thread_message_queue_nb_elems(AVThreadMessageQueue *mq); 105 106 /** 107 * Flush the message queue 108 * 109 * This function is mostly equivalent to reading and free-ing every message 110 * except that it will be done in a single operation (no lock/unlock between 111 * reads). 112 */ 113 void av_thread_message_flush(AVThreadMessageQueue *mq); 114 115 #endif /* AVUTIL_THREADMESSAGE_H */