Fix XMB thumbnail memory exhaustion on low-memory devices

gfx/gfx_thumbnail.c

@@ -53,6 +53,30 @@ gfx_thumbnail_state_t *gfx_thumb_get_ptr(void)
    return &gfx_thumb_st;
 }
 
+/* LOW-MEMORY FIX: Concurrent load management */
+
+void gfx_thumbnail_set_max_concurrent_loads(unsigned max_loads)
+{
+   gfx_thumbnail_state_t *p_gfx_thumb = &gfx_thumb_st;
+   p_gfx_thumb->max_concurrent_loads = max_loads;
+}
+
+unsigned gfx_thumbnail_get_concurrent_loads(void)
+{
+   gfx_thumbnail_state_t *p_gfx_thumb = &gfx_thumb_st;
+   return p_gfx_thumb->current_loads;
+}
+
+bool gfx_thumbnail_can_start_load(void)
+{
+   gfx_thumbnail_state_t *p_gfx_thumb = &gfx_thumb_st;
+
+   if (p_gfx_thumb->max_concurrent_loads == 0)
+      return true;
+
+   return p_gfx_thumb->current_loads < p_gfx_thumb->max_concurrent_loads;
+}
+
 /* Setters */
 
 /* When streaming thumbnails, sets time in ms that an
@@ -152,6 +176,9 @@ static void gfx_thumbnail_handle_upload(
    if (!thumbnail_tag)
       goto end;
 
+   /* LOW-MEMORY FIX: Decrement concurrent load counter */
+   p_gfx_thumb->current_loads--;
+
    /* Ensure that we are operating on the correct
     * thumbnail... */
    if (thumbnail_tag->list_id != p_gfx_thumb->list_id)
@@ -295,6 +322,10 @@ void gfx_thumbnail_request(
    if (!path_data || !thumbnail)
       return;
 
+   /* LOW-MEMORY FIX: Check if we can start a new load */
+   if (!gfx_thumbnail_can_start_load())
+      return;
+
    /* Reset thumbnail, then set 'missing' status by default
     * (saves a number of checks later) */
    gfx_thumbnail_reset(thumbnail);
@@ -317,6 +348,9 @@ void gfx_thumbnail_request(
                if (!thumbnail_tag)
                   goto end;
 
+               /* LOW-MEMORY FIX: Increment concurrent load counter */
+               p_gfx_thumb->current_loads++;
+
                /* Configure user data */
                thumbnail_tag->thumbnail = thumbnail;
                thumbnail_tag->list_id   = p_gfx_thumb->list_id;

gfx/gfx_thumbnail.h

@@ -127,6 +127,11 @@ struct gfx_thumbnail_state
    /* When true, 'fade in' animation will also be
     * triggered for missing thumbnails */
    bool fade_missing;
+
+   /* LOW-MEMORY FIX: Maximum number of concurrent thumbnail load tasks
+    * Helps prevent memory exhaustion on low-memory devices (RPi, Switch, etc.) */
+   unsigned max_concurrent_loads;
+   unsigned current_loads;
 };
 
 typedef struct gfx_thumbnail_state gfx_thumbnail_state_t;
@@ -151,6 +156,20 @@ void gfx_thumbnail_set_fade_duration(float duration);
  *   any 'thumbnail unavailable' notifications */
 void gfx_thumbnail_set_fade_missing(bool fade_missing);
 
+/* LOW-MEMORY FIX: Concurrent load management API */
+
+/* Sets maximum number of concurrent thumbnail load tasks
+ * allowed at any time. Helps prevent memory exhaustion on
+ * low-memory devices.
+ * > Use 0 for unlimited (default behavior) */
+void gfx_thumbnail_set_max_concurrent_loads(unsigned max_loads);
+
+/* Returns current number of active thumbnail load tasks */
+unsigned gfx_thumbnail_get_concurrent_loads(void);
+
+/* Returns whether a new thumbnail load can be started */
+bool gfx_thumbnail_can_start_load(void);
+
 /* Core interface */
 
 /* When called, prevents the handling of any pending

menu/drivers/xmb.c

@@ -6847,6 +6847,12 @@ static void xmb_render(void *data,
    unsigned last                  = (unsigned)end;
    unsigned gfx_thumbnail_upscale_threshold = settings->uints.gfx_thumbnail_upscale_threshold;
    bool network_on_demand_thumbnails        = settings->bools.network_on_demand_thumbnails;
+   /* LOW-MEMORY FIX: Variables for rapid scroll detection
+    * Must be declared at block start for C89 compliance */
+   static retro_time_t last_scroll_time = 0;
+   static unsigned scroll_count = 0;
+   retro_time_t current_time;
+   bool rapid_scroll;
 
    if (!xmb)
       return;
@@ -7150,57 +7156,99 @@ static void xmb_render(void *data,
    /* Handle any pending icon thumbnail load requests */
    if (xmb->thumbnails.pending_icons != XMB_PENDING_THUMBNAIL_NONE)
    {
-      /* Limit image loading per frame to prevent slowdowns,
-       * and hide the usual icon while pending */
-      uint8_t max_per_frame = 2;
-      uint8_t cur_per_frame = 0;
+      /* LOW-MEMORY FIX: Detect rapid scrolling and defer thumbnail loading
+       * This prevents texture exhaustion on devices like Raspberry Pi and Switch */
+      current_time = cpu_features_get_time_usec();
 
-      /* Based on height of screen calculate the available entries that are visible */
-      if (height)
-         xmb_calculate_visible_range(xmb, height, end, (unsigned)selection, &first, &last);
+      /* Count scrolls within 100ms window */
+      if (current_time - last_scroll_time < 100000)
+         scroll_count++;
+      else
+         scroll_count = 1;
 
-      xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_NONE;
+      last_scroll_time = current_time;
 
-      for (i = first; i <= last; i++)
+      /* If scrolling rapidly (>5 scrolls in 100ms), skip thumbnail loading */
+      rapid_scroll = (scroll_count > 5);
+
+      if (!rapid_scroll)
       {
-         xmb_node_t *node = (xmb_node_t*)selection_buf->list[i].userdata;
-         xmb_icons_t *thumbnail_icon;
+         /* Limit image loading per frame to prevent slowdowns,
+          * and hide the usual icon while pending */
+         uint8_t max_per_frame = 2;
+         uint8_t cur_per_frame = 0;
 
-         if (!node)
-            continue;
+         /* Based on height of screen calculate the available entries that are visible */
+         if (height)
+            xmb_calculate_visible_range(xmb, height, end, (unsigned)selection, &first, &last);
 
-         thumbnail_icon = &node->thumbnail_icon;
+         xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_NONE;
 
-         if (cur_per_frame >= max_per_frame)
+         for (i = first; i <= last; i++)
          {
-            node->icon_hide = true;
-            xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_ICONS;
-            continue;
-         }
+            xmb_node_t *node = (xmb_node_t*)selection_buf->list[i].userdata;
+            xmb_icons_t *thumbnail_icon;
+
+            if (!node)
+               continue;
+
+            thumbnail_icon = &node->thumbnail_icon;
+
+            /* LOW-MEMORY FIX: Skip loading if already at max concurrent loads */
+            if (!gfx_thumbnail_can_start_load())
+            {
+               xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_ICONS;
+               continue;
+            }
+
+            if (cur_per_frame >= max_per_frame)
+            {
+               node->icon_hide = true;
+               xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_ICONS;
+               continue;
+            }
+
+            if (     thumbnail_icon->icon.status == GFX_THUMBNAIL_STATUS_UNKNOWN
+                  && !string_is_empty(thumbnail_icon->thumbnail_path_data.icon_path))
+            {
+               node->icon_hide = false;
+               if (!xmb_load_dynamic_icon(
+                        thumbnail_icon->thumbnail_path_data.icon_path,
+                        &thumbnail_icon->icon))
+               {
+                  gfx_thumbnail_request_stream(
+                        &thumbnail_icon->thumbnail_path_data,
+                        p_anim,
+                        GFX_THUMBNAIL_ICON,
+                        playlist, i,
+                        &thumbnail_icon->icon,
+                        gfx_thumbnail_upscale_threshold,
+                        network_on_demand_thumbnails);
+               }
+               else
+                  cur_per_frame++;
+            }
 
-         if (     thumbnail_icon->icon.status == GFX_THUMBNAIL_STATUS_UNKNOWN
-               && !string_is_empty(thumbnail_icon->thumbnail_path_data.icon_path))
+            if (thumbnail_icon->icon.status == GFX_THUMBNAIL_STATUS_UNKNOWN)
+               xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_ICONS;
+         }
+      }
+      else
+      {
+         /* During rapid scroll, reset off-screen thumbnails to free memory */
+         size_t sel = menu_st->selection_ptr;
+         for (i = first; i <= last; i++)
          {
-            node->icon_hide = false;
-            if (!xmb_load_dynamic_icon(
-                     thumbnail_icon->thumbnail_path_data.icon_path,
-                     &thumbnail_icon->icon))
+            if (i != sel)
             {
-               gfx_thumbnail_request_stream(
-                     &thumbnail_icon->thumbnail_path_data,
-                     p_anim,
-                     GFX_THUMBNAIL_ICON,
-                     playlist, i,
-                     &thumbnail_icon->icon,
-                     gfx_thumbnail_upscale_threshold,
-                     network_on_demand_thumbnails);
+               xmb_node_t *other_node = (xmb_node_t*)selection_buf->list[i].userdata;
+               if (other_node)
+                  gfx_thumbnail_reset(&other_node->thumbnail_icon.icon);
             }
-            else
-               cur_per_frame++;
          }
-
-         if (thumbnail_icon->icon.status == GFX_THUMBNAIL_STATUS_UNKNOWN)
-            xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_ICONS;
+         
+         /* Still need to retry later */
+         xmb->thumbnails.pending_icons = XMB_PENDING_THUMBNAIL_ICONS;
       }
    }
    else if (xmb->thumbnails.icon.status == GFX_THUMBNAIL_STATUS_UNKNOWN
@@ -9180,6 +9228,16 @@ static void *xmb_init(void **userdata, bool video_is_threaded)
    gfx_thumbnail_set_fade_duration(-1.0f);
    gfx_thumbnail_set_fade_missing(false);
 
+   /* LOW-MEMORY FIX: Set platform-appropriate concurrent load limits
+    * Prevents texture memory exhaustion on RPi, Switch, and other low-RAM devices */
+#if defined(HAVE_OPENGLES) || defined(__SWITCH__) || defined(ANDROID)
+   /* Low-memory platforms: limit to 2 concurrent loads */
+   gfx_thumbnail_set_max_concurrent_loads(2);
+#else
+   /* Desktop platforms: allow 4 concurrent loads */
+   gfx_thumbnail_set_max_concurrent_loads(4);
+#endif
+
    xmb->use_ps3_layout                        =
          xmb_use_ps3_layout(settings->uints.menu_xmb_layout, width, height);
    xmb->last_use_ps3_layout                   = xmb->use_ps3_layout;