[SCM] libav/experimental: Make url_read_complete handle EAGAIN more intelligently. Only retry 2 - 5 times in quick succession and afterwards sleep a bit to avoid creating high CPU load without any progress.

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit f1d2b5728caa39172898043e05e2ade6f224056f
Author: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
Date:   Sun Jan 24 18:09:46 2010 +0000

    Make url_read_complete handle EAGAIN more intelligently.
    Only retry 2 - 5 times in quick succession and afterwards sleep a bit
    to avoid creating high CPU load without any progress.
    
    Originally committed as revision 21427 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/libavformat/avio.c b/libavformat/avio.c
index 706ba4a..ca022c8 100644
--- a/libavformat/avio.c
+++ b/libavformat/avio.c
@@ -19,6 +19,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/* needed for usleep() */
+#define _XOPEN_SOURCE 600
+#include <unistd.h>
 #include "libavutil/avstring.h"
 #include "libavcodec/opt.h"
 #include "os_support.h"
@@ -152,14 +155,21 @@ int url_read(URLContext *h, unsigned char *buf, int size)
 int url_read_complete(URLContext *h, unsigned char *buf, int size)
 {
     int ret, len;
+    int fast_retries = 5;
 
     len = 0;
     while (len < size) {
         ret = url_read(h, buf+len, size-len);
         if (ret == AVERROR(EAGAIN)) {
             ret = 0;
+            if (fast_retries)
+                fast_retries--;
+            else
+                usleep(1000);
         } else if (ret < 1)
             return ret < 0 ? ret : len;
+        if (ret)
+           fast_retries = FFMAX(fast_retries, 2);
         len += ret;
     }
     return len;

-- 
Libav/FFmpeg packaging