[FFmpeg-devel] [PATCH] udp: do not wait for data from the receiving thread.

[Nicolas George]

Lowest-level read protocols are supposed to be always
non-blocking: blocking, if requested, is done by
retry_transfer_wrapper, which also handles interrupting.

Fixes interrupting UDP reads.

Bug reported by Andrey Utkin.

Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
---
 libavformat/udp.c |   18 +-----------------
 1 files changed, 1 insertions(+), 17 deletions(-)


As a side note, stores to s->exit_thread and s->circular_buffer_error are
not protected by a mutex: theoretically that is a bug.


diff --git a/libavformat/udp.c b/libavformat/udp.c
index 17bf434..835bc1a 100644
--- a/libavformat/udp.c
+++ b/libavformat/udp.c
@@ -71,7 +71,6 @@ typedef struct {
 #if HAVE_PTHREADS
     pthread_t circular_buffer_thread;
     pthread_mutex_t mutex;
-    pthread_cond_t cond;
     int thread_started;
     volatile int exit_thread;
 #endif
@@ -385,14 +384,10 @@ static void *circular_buffer_task( void *_URLContext)
         }
         pthread_mutex_lock(&s->mutex);
         av_fifo_generic_write(s->fifo, s->tmp, len+4, NULL);
-        pthread_cond_signal(&s->cond);
         pthread_mutex_unlock(&s->mutex);
     }
 
 end:
-    pthread_mutex_lock(&s->mutex);
-    pthread_cond_signal(&s->cond);
-    pthread_mutex_unlock(&s->mutex);
     return NULL;
 }
 #endif
@@ -558,11 +553,6 @@ static int udp_open(URLContext *h, const char *uri, int flags)
             av_log(h, AV_LOG_ERROR, "pthread_mutex_init failed : %s\n", strerror(ret));
             goto fail;
         }
-        ret = pthread_cond_init(&s->cond, NULL);
-        if (ret != 0) {
-            av_log(h, AV_LOG_ERROR, "pthread_cond_init failed : %s\n", strerror(ret));
-            goto cond_fail;
-        }
         ret = pthread_create(&s->circular_buffer_thread, NULL, circular_buffer_task, h);
         if (ret != 0) {
             av_log(h, AV_LOG_ERROR, "pthread_create failed : %s\n", strerror(ret));
@@ -575,8 +565,6 @@ static int udp_open(URLContext *h, const char *uri, int flags)
     return 0;
 #if HAVE_PTHREADS
  thread_fail:
-    pthread_cond_destroy(&s->cond);
- cond_fail:
     pthread_mutex_destroy(&s->mutex);
 #endif
  fail:
@@ -614,13 +602,10 @@ static int udp_read(URLContext *h, uint8_t *buf, int size)
             } else if(s->circular_buffer_error){
                 pthread_mutex_unlock(&s->mutex);
                 return s->circular_buffer_error;
-            } else if(h->flags & AVIO_FLAG_NONBLOCK) {
+            } else {
                 pthread_mutex_unlock(&s->mutex);
                 return AVERROR(EAGAIN);
             }
-            else {
-                pthread_cond_wait(&s->cond, &s->mutex);
-            }
         } while( 1);
     }
 #endif
@@ -674,7 +659,6 @@ static int udp_close(URLContext *h)
     }
 
     pthread_mutex_destroy(&s->mutex);
-    pthread_cond_destroy(&s->cond);
 #endif
     return 0;
 }
-- 
1.7.9.1