picture_pool: release unused pictures immediately

When the pool is released, the pictures were destroyed only once all
references to all pooled pictures were released. Now, each picture is
destroyed individually when it is no longer referenced.

src/misc/picture_pool.c

@@ -46,7 +46,7 @@ struct picture_pool_t {
     picture_t  *picture[];
 };
 
-void picture_pool_Release(picture_pool_t *pool)
+static void picture_pool_Destroy(picture_pool_t *pool)
 {
     bool destroy;
 
@@ -58,31 +58,37 @@ void picture_pool_Release(picture_pool_t *pool)
     if (likely(!destroy))
         return;
 
-    for (unsigned i = 0; i < pool->picture_count; i++)
-        picture_Release(pool->picture[i]);
-
     vlc_mutex_destroy(&pool->lock);
     vlc_free(pool);
 }
 
-static void picture_pool_ReleasePicture(picture_t *picture)
+void picture_pool_Release(picture_pool_t *pool)
 {
-    picture_priv_t *priv = (picture_priv_t *)picture;
+    for (unsigned i = 0; i < pool->picture_count; i++)
+        picture_Release(pool->picture[i]);
+    picture_pool_Destroy(pool);
+}
+
+static void picture_pool_ReleasePicture(picture_t *clone)
+{
+    picture_priv_t *priv = (picture_priv_t *)clone;
     uintptr_t sys = (uintptr_t)priv->gc.opaque;
     picture_pool_t *pool = (void *)(sys & ~(pool_max - 1));
     unsigned offset = sys & (pool_max - 1);
+    picture_t *picture = pool->picture[offset];
+
+    free(clone);
 
     if (pool->pic_unlock != NULL)
-        pool->pic_unlock(pool->picture[offset]);
+        pool->pic_unlock(picture);
+    picture_Release(picture);
 
     vlc_mutex_lock(&pool->lock);
     assert(!(pool->available & (1ULL << offset)));
     pool->available |= 1ULL << offset;
     vlc_mutex_unlock(&pool->lock);
 
-    picture_pool_Release(pool);
-
-    free(picture);
+    picture_pool_Destroy(pool);
 }
 
 static picture_t *picture_pool_ClonePicture(picture_pool_t *pool,
@@ -102,8 +108,10 @@ static picture_t *picture_pool_ClonePicture(picture_pool_t *pool,
     }
 
     picture_t *clone = picture_NewFromResource(&picture->format, &res);
-    if (likely(clone != NULL))
+    if (likely(clone != NULL)) {
         ((picture_priv_t *)clone)->gc.opaque = (void *)sys;
+        picture_Hold(picture);
+    }
     return clone;
 }
 
@@ -126,7 +134,6 @@ picture_pool_t *picture_pool_NewExtended(const picture_pool_configuration_t *cfg
     memcpy(pool->picture, cfg->picture,
            cfg->picture_count * sizeof (picture_t *));
     return pool;
-
 }
 
 picture_pool_t *picture_pool_New(unsigned count, picture_t *const *tab)