udp: switch custom fifo to libavutil fifo.

This also allows us to drop the semaphore as our fifo is lock free.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/udp.c

@@ -29,13 +29,13 @@
 #include "avformat.h"
 #include "avio_internal.h"
 #include "libavutil/parseutils.h"
+#include "libavutil/fifo.h"
 #include <unistd.h>
 #include "internal.h"
 #include "network.h"
 #include "os_support.h"
 #include "url.h"
 #include <pthread.h>
-#include <semaphore.h>
 #include <sys/resource.h>
 #include <sys/time.h>
 
@@ -56,15 +56,11 @@ typedef struct {
     int is_connected;
 
     /* Circular Buffer variables for use in UDP receive code */
-    unsigned char *circular_buffer;
-    int circular_buffer_head;
     int circular_buffer_size;
-    int circular_buffer_tail;
-    int circular_buffer_available;
+    AVFifoBuffer *fifo;
     int circular_buffer_available_max;
     int circular_buffer_error;
     pthread_t circular_buffer_thread;
-    sem_t circular_buffer_semaphore;
 } UDPContext;
 
 #define UDP_TX_BUF_SIZE 32768
@@ -345,31 +341,28 @@ static void *circular_buffer_task( void *_URLContext)
             continue;
 
         /* How much do we have left to the end of the buffer */
-        left = s->circular_buffer_size-s->circular_buffer_head;
         /* Whats the minimum we can read so that we dont comletely fill the buffer */
-        sem_wait( &s->circular_buffer_semaphore);
-        left = FFMIN( left, s->circular_buffer_size-s->circular_buffer_available);
-        sem_post( &s->circular_buffer_semaphore );
+        left = av_fifo_space(s->fifo);
+        left = FFMIN(left, s->fifo->end - s->fifo->wptr);
+
         /* No Space left, error, what do we do now */
         if( !left) {
             av_log(h, AV_LOG_ERROR, "circular_buffer: OVERRUN\n");
             s->circular_buffer_error = EIO;
             return NULL;
         }
-        len = recv(s->udp_fd, s->circular_buffer+s->circular_buffer_head, left, 0);
+
+        len = recv(s->udp_fd, s->fifo->wptr, left, 0);
         if (len < 0) {
             if (ff_neterrno() != AVERROR(EAGAIN) && ff_neterrno() != AVERROR(EINTR)) {
                 s->circular_buffer_error = EIO;
                 return NULL;
             }
         }
-        s->circular_buffer_head += len;
-        sem_wait( &s->circular_buffer_semaphore);
-        s->circular_buffer_available += len;
-        s->circular_buffer_available_max = FFMAX( s->circular_buffer_available_max, s->circular_buffer_available);
-        sem_post( &s->circular_buffer_semaphore );
-        if( s->circular_buffer_head>=s->circular_buffer_size)
-            s->circular_buffer_head -= s->circular_buffer_size;
+        s->fifo->wptr += len;
+        if (s->fifo->wptr >= s->fifo->end)
+            s->fifo->wptr = s->fifo->buffer;
+        s->fifo->wndx += len;
     }
 
     return NULL;
@@ -516,11 +509,7 @@ static int udp_open(URLContext *h, const char *uri, int flags)
 
     if (!is_output && s->circular_buffer_size) {
         /* start the task going */
-        s->circular_buffer = av_malloc( s->circular_buffer_size);
-        if (sem_init( &s->circular_buffer_semaphore, PTHREAD_PROCESS_PRIVATE, 1 )) {
-            av_log(h, AV_LOG_ERROR, "sem_init failed\n");
-            goto fail;
-        }
+        s->fifo = av_fifo_alloc(s->circular_buffer_size);
         if (pthread_create(&s->circular_buffer_thread, NULL, circular_buffer_task, h)) {
             av_log(h, AV_LOG_ERROR, "pthread_create failed\n");
             goto fail;
@@ -531,10 +520,7 @@ static int udp_open(URLContext *h, const char *uri, int flags)
  fail:
     if (udp_fd >= 0)
         closesocket(udp_fd);
-        if (s->circular_buffer) {
-            sem_destroy( &s->circular_buffer_semaphore);
-            av_free( s->circular_buffer);
-        }
+        av_fifo_free(s->fifo);
     av_free(s);
     return AVERROR(EIO);
 }
@@ -551,30 +537,12 @@ static int udp_read(URLContext *h, uint8_t *buf, int size)
     if (s->circular_buffer_thread) {
 
         do {
-            sem_wait( &s->circular_buffer_semaphore );
-            avail = s->circular_buffer_available;
-            sem_post( &s->circular_buffer_semaphore );
+            avail = av_fifo_size(s->fifo);
             if (avail) { // >=size) {
 
                 // Maximum amount available
                 size = FFMIN( avail, size);
-                // Whats left till the end of the circular buffer
-                left = s->circular_buffer_size-s->circular_buffer_tail;
-                // How much do we need, all?
-                left = FFMIN( left, size);
-                // Get the first block
-                memcpy( buf, s->circular_buffer+s->circular_buffer_tail, left);
-                // Have we any more, this will be from the start of the buffer
-                if (size-left)
-                    memcpy( buf+left, s->circular_buffer, size-left);
-                // Check for the tail wrapping around
-                s->circular_buffer_tail += size;
-                if( s->circular_buffer_tail>=s->circular_buffer_size)
-                    s->circular_buffer_tail -= s->circular_buffer_size;
-                // Update the available amount
-                sem_wait( &s->circular_buffer_semaphore );
-                s->circular_buffer_available -= size;
-                sem_post( &s->circular_buffer_semaphore );
+                av_fifo_generic_read(s->fifo, buf, size, NULL);
                 return size;
             }
             else {
@@ -627,11 +595,8 @@ static int udp_close(URLContext *h)
     if (s->is_multicast && (h->flags & AVIO_FLAG_READ))
         udp_leave_multicast_group(s->udp_fd, (struct sockaddr *)&s->dest_addr);
     closesocket(s->udp_fd);
-    if (s->circular_buffer) {
-        sem_destroy( &s->circular_buffer_semaphore);
-        av_free( s->circular_buffer);
     av_log( h, AV_LOG_INFO, "circular_buffer_info max:%d%%\r\n", (s->circular_buffer_available_max*100)/s->circular_buffer_size);
-    }
+    av_fifo_free(s->fifo);
     av_free(s);
     return 0;
 }