util.dbuffer: Add efficient shortcuts for discard() in certain cases
If the buffer is already empty, nothing to do. If we're throwing away the
whole buffer, we can just empty it and avoid read_chunk() (which in turn
may collapse()). These shortcuts are much more efficient.
--- a/util/dbuffer.lua Tue Oct 11 11:34:47 2022 +0100
+++ b/util/dbuffer.lua Tue Oct 11 11:37:55 2022 +0100
@@ -91,8 +91,12 @@
end
function dbuffer_methods:discard(requested_bytes)
- if requested_bytes > self._length then
- return nil;
+ if self._length == 0 then return true; end
+ if not requested_bytes or requested_bytes >= self._length then
+ self.front_consumed = 0;
+ self._length = 0;
+ for _ in self.items:consume() do end
+ return true;
end
local chunk, read_bytes = self:read_chunk(requested_bytes);