Andreas Rheinhardt (12020-08-12):
> When one merges two AVFilterChannelLayouts structs, there is no need to
> allocate a new one. Instead one can reuse one of the two given ones.
> If one does this, one also doesn't need to update the references of the
> AVFilterChannelLayouts that is reused. Therefore this commit reuses the
> structure with the higher refcount.
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
> ---
> This can of course be applied independently of 7-21.
>
> libavfilter/formats.c | 48 +++++++++++++++++++------------------------
> 1 file changed, 21 insertions(+), 27 deletions(-)
>
> diff --git a/libavfilter/formats.c b/libavfilter/formats.c
> index 00d050e439..2d33dd7afe 100644
> --- a/libavfilter/formats.c
> +++ b/libavfilter/formats.c
> @@ -48,13 +48,13 @@ do {
> \
> av_freep(&a); \
> } while (0)
>
> -#define MERGE_REF(ret, a, fmts, type, fail) \
> +#define MERGE_REF(ret, a, fmts, type, fail_statement) \
> do { \
> type ***tmp; \
> \
> if (!(tmp = av_realloc_array(ret->refs, ret->refcount + a->refcount, \
> sizeof(*tmp)))) \
> - goto fail; \
> + { fail_statement } \
> ret->refs = tmp; \
> MERGE_REF_NO_ALLOC(ret, a, fmts); \
> } while (0)
> @@ -157,10 +157,10 @@ AVFilterFormats *ff_merge_samplerates(AVFilterFormats
> *a,
> if (a->nb_formats && b->nb_formats) {
> MERGE_FORMATS(ret, a, b, formats, nb_formats, AVFilterFormats, fail);
> } else if (a->nb_formats) {
> - MERGE_REF(a, b, formats, AVFilterFormats, fail);
> + MERGE_REF(a, b, formats, AVFilterFormats, return NULL;);
> ret = a;
> } else {
> - MERGE_REF(b, a, formats, AVFilterFormats, fail);
> + MERGE_REF(b, a, formats, AVFilterFormats, return NULL;);
> ret = b;
> }
>
> @@ -177,7 +177,7 @@ fail:
> AVFilterChannelLayouts *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
> AVFilterChannelLayouts *b)
> {
> - AVFilterChannelLayouts *ret = NULL;
> + uint64_t *channel_layouts;
> unsigned a_all = a->all_layouts + a->all_counts;
> unsigned b_all = b->all_layouts + b->all_counts;
> int ret_max, ret_nb = 0, i, j, round;
> @@ -201,15 +201,13 @@ AVFilterChannelLayouts
> *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
> return NULL;
> b->nb_channel_layouts = j;
> }
> - MERGE_REF(b, a, channel_layouts, AVFilterChannelLayouts, fail);
> + MERGE_REF(b, a, channel_layouts, AVFilterChannelLayouts, return
> NULL;);
> return b;
> }
>
> ret_max = a->nb_channel_layouts + b->nb_channel_layouts;
> - if (!(ret = av_mallocz(sizeof(*ret))) ||
> - !(ret->channel_layouts = av_malloc_array(ret_max,
> -
> sizeof(*ret->channel_layouts))))
> - goto fail;
> + if (!(channel_layouts = av_malloc_array(ret_max,
> sizeof(channel_layouts))))
sizeof(*channel_layouts)
> + return NULL;
>
> /* a[known] intersect b[known] */
> for (i = 0; i < a->nb_channel_layouts; i++) {
> @@ -217,7 +215,7 @@ AVFilterChannelLayouts
> *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
> continue;
> for (j = 0; j < b->nb_channel_layouts; j++) {
> if (a->channel_layouts[i] == b->channel_layouts[j]) {
> - ret->channel_layouts[ret_nb++] = a->channel_layouts[i];
> + channel_layouts[ret_nb++] = a->channel_layouts[i];
> a->channel_layouts[i] = b->channel_layouts[j] = 0;
> }
> }
> @@ -232,7 +230,7 @@ AVFilterChannelLayouts
> *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
> bfmt = FF_COUNT2LAYOUT(av_get_channel_layout_nb_channels(fmt));
> for (j = 0; j < b->nb_channel_layouts; j++)
> if (b->channel_layouts[j] == bfmt)
> - ret->channel_layouts[ret_nb++] = a->channel_layouts[i];
> + channel_layouts[ret_nb++] = a->channel_layouts[i];
> }
> /* 1st round: swap to prepare 2nd round; 2nd round: put it back */
> FFSWAP(AVFilterChannelLayouts *, a, b);
> @@ -243,27 +241,23 @@ AVFilterChannelLayouts
> *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
> continue;
> for (j = 0; j < b->nb_channel_layouts; j++)
> if (a->channel_layouts[i] == b->channel_layouts[j])
> - ret->channel_layouts[ret_nb++] = a->channel_layouts[i];
> + channel_layouts[ret_nb++] = a->channel_layouts[i];
> }
>
> - ret->nb_channel_layouts = ret_nb;
> - if (!ret->nb_channel_layouts)
> + if (!ret_nb)
> goto fail;
>
> - ret->refs = av_realloc_array(NULL, a->refcount + b->refcount,
> - sizeof(*ret->refs));
> - if (!ret->refs)
> - goto fail;
> - MERGE_REF_NO_ALLOC(ret, a, channel_layouts);
> - MERGE_REF_NO_ALLOC(ret, b, channel_layouts);
> - return ret;
> + if (a->refcount > b->refcount)
> + FFSWAP(AVFilterChannelLayouts *, a, b);
I do not think it is just as simple as that: if you swap, then b->refs
points to the references of a and a->refs points to the references of b.
Then the MERGE_REF() below will update a->refs, i.e. the references of
b, which are already valid, and not b->refs, which need to.
Better leave this optimization for later. Especially if we consider
using a linked list as I suggested.
> +
> + MERGE_REF(b, a, channel_layouts, AVFilterChannelLayouts, goto fail;);
> + av_freep(&b->channel_layouts);
> + b->channel_layouts = channel_layouts;
> + b->nb_channel_layouts = ret_nb;
> + return b;
>
> fail:
> - if (ret) {
> - av_assert1(!ret->refs);
> - av_freep(&ret->channel_layouts);
> - av_freep(&ret);
> - }
> + av_free(channel_layouts);
> return NULL;
> }
LGTM apart from that.
Regards,
--
Nicolas George
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