[FFmpeg-cvslog] lavfi/vulkan: use av_get_random_seed instead of rand

[Lynne]

ffmpeg | branch: master | Lynne <dev at lynne.ee> | Fri May 29 13:10:58 2020 +0100| [83fa39eb06d0d720422e8a5408d15ba472a82ea6] | committer: Lynne

lavfi/vulkan: use av_get_random_seed instead of rand

We need at least a few bits of entropy to determine the start index of each
queue, in order to let filters run in parallel as much as possible, and
rand() is not thread safe and disrupts any external API's usage of rand,
so instead replace it with av_get_random_seed.
While it has more overhead than rand, we only run it once per filter upon init.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=83fa39eb06d0d720422e8a5408d15ba472a82ea6
---

 libavfilter/vf_avgblur_vulkan.c   | 3 ++-
 libavfilter/vf_chromaber_vulkan.c | 3 ++-
 libavfilter/vf_overlay_vulkan.c   | 3 ++-
 libavfilter/vf_scale_vulkan.c     | 3 ++-
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/libavfilter/vf_avgblur_vulkan.c b/libavfilter/vf_avgblur_vulkan.c
index 12d57e0875..89763345d9 100644
--- a/libavfilter/vf_avgblur_vulkan.c
+++ b/libavfilter/vf_avgblur_vulkan.c
@@ -16,6 +16,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/random_seed.h"
 #include "libavutil/opt.h"
 #include "vulkan.h"
 #include "internal.h"
@@ -99,7 +100,7 @@ static av_cold int init_filter(AVFilterContext *ctx, AVFrame *in)
 
     s->vkctx.queue_family_idx = s->vkctx.hwctx->queue_family_comp_index;
     s->vkctx.queue_count = GET_QUEUE_COUNT(s->vkctx.hwctx, 0, 1, 0);
-    s->vkctx.cur_queue_idx = rand() % s->vkctx.queue_count;
+    s->vkctx.cur_queue_idx = av_get_random_seed() % s->vkctx.queue_count;
 
     { /* Create shader for the horizontal pass */
         desc_i[0].updater = s->input_images;
diff --git a/libavfilter/vf_chromaber_vulkan.c b/libavfilter/vf_chromaber_vulkan.c
index 1bee5e10f8..12dfebb1fe 100644
--- a/libavfilter/vf_chromaber_vulkan.c
+++ b/libavfilter/vf_chromaber_vulkan.c
@@ -16,6 +16,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/random_seed.h"
 #include "libavutil/opt.h"
 #include "vulkan.h"
 #include "internal.h"
@@ -75,7 +76,7 @@ static av_cold int init_filter(AVFilterContext *ctx, AVFrame *in)
 
     s->vkctx.queue_family_idx = s->vkctx.hwctx->queue_family_comp_index;
     s->vkctx.queue_count = GET_QUEUE_COUNT(s->vkctx.hwctx, 0, 1, 0);
-    s->vkctx.cur_queue_idx = rand() % s->vkctx.queue_count;
+    s->vkctx.cur_queue_idx = av_get_random_seed() % s->vkctx.queue_count;
 
     s->pl = ff_vk_create_pipeline(ctx);
     if (!s->pl)
diff --git a/libavfilter/vf_overlay_vulkan.c b/libavfilter/vf_overlay_vulkan.c
index 60a7356456..60ca85fd08 100644
--- a/libavfilter/vf_overlay_vulkan.c
+++ b/libavfilter/vf_overlay_vulkan.c
@@ -16,6 +16,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/random_seed.h"
 #include "libavutil/opt.h"
 #include "vulkan.h"
 #include "internal.h"
@@ -89,7 +90,7 @@ static av_cold int init_filter(AVFilterContext *ctx)
 
     s->vkctx.queue_family_idx = s->vkctx.hwctx->queue_family_comp_index;
     s->vkctx.queue_count = GET_QUEUE_COUNT(s->vkctx.hwctx, 0, 1, 0);
-    s->vkctx.cur_queue_idx = rand() % s->vkctx.queue_count;
+    s->vkctx.cur_queue_idx = av_get_random_seed() % s->vkctx.queue_count;
 
     { /* Create the shader */
         const int planes = av_pix_fmt_count_planes(s->vkctx.output_format);
diff --git a/libavfilter/vf_scale_vulkan.c b/libavfilter/vf_scale_vulkan.c
index 9b2e5b92f6..35ea2e1e5d 100644
--- a/libavfilter/vf_scale_vulkan.c
+++ b/libavfilter/vf_scale_vulkan.c
@@ -16,6 +16,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/random_seed.h"
 #include "libavutil/opt.h"
 #include "vulkan.h"
 #include "scale_eval.h"
@@ -117,7 +118,7 @@ static av_cold int init_filter(AVFilterContext *ctx, AVFrame *in)
 
     s->vkctx.queue_family_idx = s->vkctx.hwctx->queue_family_comp_index;
     s->vkctx.queue_count = GET_QUEUE_COUNT(s->vkctx.hwctx, 0, 1, 0);
-    s->vkctx.cur_queue_idx = rand() % s->vkctx.queue_count;
+    s->vkctx.cur_queue_idx = av_get_random_seed() % s->vkctx.queue_count;
 
     switch (s->scaler) {
     case F_NEAREST: