[FFmpeg-devel] cache: read ahead to avoid excessive small requests

[Michael Niedermayer]

On Sat, Sep 22, 2018 at 07:32:28PM +0200, Robert Nagy wrote:
> diff --git a/libavformat/cache.c b/libavformat/cache.c
> index 66bbbf54c9..48ff5ab363 100644
> --- a/libavformat/cache.c
> +++ b/libavformat/cache.c
> @@ -153,6 +153,38 @@ fail:
>      return ret;
>  }
> 
> +static int cache_read_ahead(URLContext *h)
> +{
> +    Context *c= h->priv_data;
> +    int64_t r, read_ahead, pos;
> +    uint8_t buf[32768];
> +
> +    pos = c->logical_pos;
> +    read_ahead = c->read_ahead_limit < 0
> +        ? 512 * 512
> +        : FFMIN(512 * 512, c->read_ahead_limit);
> +
> +    while (read_ahead > 0) {
> +        r = ffurl_read(c->inner, buf, FFMIN(read_ahead, sizeof(buf)));
> +        if (r == AVERROR_EOF) {
> +            c->is_true_eof = 1;
> +            av_assert0(c->end >= c->logical_pos);
> +        }
> +        if (r<=0)
> +            break;
> +        c->inner_pos += r;
> +
> +        add_entry(h, buf, r);
> +        c->logical_pos += r;
> +        c->end = FFMAX(c->end, c->logical_pos);
> +        read_ahead -= r;
> +    }
> +
> +    c->logical_pos = pos;
> +
> +    return r < 0 ? r : 0;
> +}
> +
>  static int cache_read(URLContext *h, unsigned char *buf, int size)
>  {
>      Context *c= h->priv_data;

> @@ -215,6 +247,10 @@ static int cache_read(URLContext *h, unsigned
> char *buf, int size)

still not cleanly applying (due to new lines)

Applying: cache: read ahead to avoid excessive small requests
error: corrupt patch at line 45
error: could not build fake ancestor
Patch failed at 0001 cache: read ahead to avoid excessive small requests
hint: Use 'git am --show-current-patch' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The greatest way to live with honor in this world is to be what we pretend
to be. -- Socrates
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