Diff

net.server_epoll: Avoid concatenating buffer with single item Saves creating a string that'll be identical to buffer[1] anyways, as well as a C function call. Depending on Lua version and length of the string, this could be reusing an interned string, but a longer one would probably be duplicated for no reason. Having exactly one item in the buffer seems like it would be fairly common, but I have not done an extensive study. If opportunistic writes are enabled then it will be even more likely. This special case could be optimized like this in table.concat but it does not look like it is.

--- a/net/server_epoll.lua	Tue Dec 24 08:42:53 2019 +0000
+++ b/net/server_epoll.lua	Sat Dec 28 06:18:58 2019 +0100
@@ -408,7 +408,7 @@
 	self:onconnect();
 	if not self.conn then return; end -- could have been closed in onconnect
 	local buffer = self.writebuffer;
-	local data = t_concat(buffer);
+	local data = #buffer == 1 and buffer[1] or t_concat(buffer);
 	local ok, err, partial = self.conn:send(data);
 	if ok then
 		self:set(nil, false);