avoid duplicate downloads on sequential requests of same URL

1 files changed, 15 insertions, 7 deletions

diff --git a/downloader.lua b/downloader.lua
index 768d726..a8519dd 100644
--- a/downloader.lua
+++ b/downloader.lua
@@ -29,16 +29,24 @@ function mt:exec(url, file, cb)
 		args = cmd,
 		playback_only = false,
 	}, function(success, res)
-		self.running = false
-		self:exec_next()
-		if success and res.status == 0 then
-			os.rename(tmp, file)
-			if cb then
-				cb(url, file)
-			end
+		success = success and res.status == 0
+		if success then
+			success = os.rename(tmp, file)
 		else
 			os.remove(tmp)
 		end
+
+		-- execute next download after renaming the file but before
+		-- executing the callback function. this avoids duplicate
+		-- downloads when the same file is requested twice in a row,
+		-- without unnecessarily waiting for the callback to complete
+		-- before starting the next download.
+		self.running = false
+		self:exec_next()
+
+		if success and cb then
+			cb(url, file)
+		end
 	end)
 end