Add an id to the Thumbnailer.state table so we can ignore messages from workers that are for previous state versions (we may get messages from workers for the previous video after the video has changed).

Author: blank_name

src/thumbnailer_server.lua

@@ -129,6 +129,7 @@ function do_worker_job(state_json_string, frames_json_string)
         msg.error("Failed to parse state JSON")
         return
     end
+    local state_id = thumb_state.id
 
     local thumbnail_indexes, err = utils.parse_json(frames_json_string)
     if err then
@@ -169,7 +170,7 @@ function do_worker_job(state_json_string, frames_json_string)
         -- Grab the "middle" of the thumbnail duration instead of the very start, and leave some margin in the end
         local timestamp = math.min(file_duration - 0.25, (thumb_idx + 0.5) * thumb_state.thumbnail_delta)
 
-        mp.commandv("script-message", "mpv_thumbnail_script-progress", tostring(thumbnail_index))
+        mp.commandv("script-message", "mpv_thumbnail_script-progress", tostring(state_id), tostring(thumbnail_index))
 
         -- The expected size (raw BGRA image)
         local thumbnail_raw_size = (thumb_state.thumbnail_size.w * thumb_state.thumbnail_size.h * 4)
@@ -234,7 +235,7 @@ function do_worker_job(state_json_string, frames_json_string)
         end
 
         msg.debug("Finished work on thumbnail", thumb_idx)
-        mp.commandv("script-message", "mpv_thumbnail_script-ready", tostring(thumbnail_index), thumbnail_path)
+        mp.commandv("script-message", "mpv_thumbnail_script-ready", tostring(state_id), tostring(thumbnail_index), thumbnail_path)
     end
 
     msg.debug(("Generating %d thumbnails @ %dx%d for %q"):format(

src/thumbnailer_shared.lua

@@ -2,6 +2,9 @@ local Thumbnailer = {
     cache_directory = thumbnailer_options.cache_directory,
 
     state = {
+        -- Used to make sure updates sent to us by workers correspond to the
+        -- current state (the video hasn't changed)
+        id = 0,
         ready = false,
         available = false,
         enabled = false,
@@ -33,7 +36,10 @@ local Thumbnailer = {
 }
 
 function Thumbnailer:clear_state()
+    local prev_state_id = self.state.id
+
     clear_table(self.state)
+    self.state.id = prev_state_id + 1
     self.state.ready = false
     self.state.available = false
     self.state.finished_thumbnails = 0
@@ -46,7 +52,11 @@ function Thumbnailer:on_file_loaded()
     self:clear_state()
 end
 
-function Thumbnailer:on_thumb_ready(index)
+function Thumbnailer:on_thumb_ready(state_id, index)
+    if self.state.id ~= state_id then
+      return
+    end
+
     self.state.thumbnails[index] = 1
 
     -- Full recount instead of a naive increment (let's be safe!)
@@ -58,7 +68,11 @@ function Thumbnailer:on_thumb_ready(index)
     end
 end
 
-function Thumbnailer:on_thumb_progress(index)
+function Thumbnailer:on_thumb_progress(state_id, index)
+    if self.state.id ~= state_id then
+      return
+    end
+
     self.state.thumbnails[index] = math.max(self.state.thumbnails[index], 0)
 end
 
@@ -259,11 +273,11 @@ end
 function Thumbnailer:register_client()
     self.worker_register_timeout = mp.get_time() + 2
 
-    mp.register_script_message("mpv_thumbnail_script-ready", function(index, path)
-        self:on_thumb_ready(tonumber(index), path)
+    mp.register_script_message("mpv_thumbnail_script-ready", function(state_id, index, path)
+        self:on_thumb_ready(tonumber(state_id), tonumber(index), path)
     end)
-    mp.register_script_message("mpv_thumbnail_script-progress", function(index, path)
-        self:on_thumb_progress(tonumber(index), path)
+    mp.register_script_message("mpv_thumbnail_script-progress", function(state_id, index, path)
+        self:on_thumb_progress(tonumber(state_id), tonumber(index), path)
     end)
 
     mp.register_script_message("mpv_thumbnail_script-worker", function(worker_name)
@@ -371,7 +385,7 @@ function Thumbnailer:start_worker_jobs()
         return
     end
 
-    local worker_list = {}
+    local worker_list = { state_id = self.state.id }
     for worker_name in pairs(self.workers) do table.insert(worker_list, worker_name) end
 
     local worker_count = #worker_list