[FFmpeg-devel] [PATCH v2 1/1] avformat/http: flushing tcp receive buffer when it is write only mode

[Steven Liu]

> On 4 Apr 2018, at 19:08, vdixit at akamai.com wrote:
> 
> From: Vishwanath Dixit <vdixit at akamai.com>
> 
> In write only mode, the TCP receive buffer's data keeps growing with
> http response messages and the buffer eventually becomes full.
> This results in zero tcp window size, which in turn causes unwanted
> issues, like, terminated tcp connection. The issue is apparent when
> http persistent connection is enabled in hls/dash live streaming use
> cases. To overcome this issue, the logic here reads the buffer data
> when a file transfer is completed, so that any accumulated data in
> the recieve buffer gets flushed out.
> ---
> libavformat/http.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
> 
> diff --git a/libavformat/http.c b/libavformat/http.c
> index 983034f..0c39e9c 100644
> --- a/libavformat/http.c
> +++ b/libavformat/http.c
> @@ -1627,6 +1627,18 @@ static int http_shutdown(URLContext *h, int flags)
>         ((flags & AVIO_FLAG_READ) && s->chunked_post && s->listen)) {
>         ret = ffurl_write(s->hd, footer, sizeof(footer) - 1);
>         ret = ret > 0 ? 0 : ret;
> +        /* flush the receive buffer when it is write only mode */
> +        if (!(flags & AVIO_FLAG_READ)) {
> +            char buf[1024];
> +            int read_ret;
> +            s->hd->flags |= AVIO_FLAG_NONBLOCK;
> +            read_ret = ffurl_read(s->hd, buf, sizeof(buf));
> +            s->hd->flags &= ~AVIO_FLAG_NONBLOCK;
> +            if (read_ret < 0 && read_ret != AVERROR(EAGAIN)) {
> +                av_log(h, AV_LOG_ERROR, "URL read error:  %d\n", read_ret);
> +                ret = read_ret;
> +            }
> +        }
>         s->end_chunked_post = 1;
>     }
> 
> -- 
> 1.9.1
> 

LGTM, but i cannot sure the buf and read_ret define in the paragraph is a good style.

Thanks
Steven