Motivation:
I noticed WebSocketServerExtensionHandler taking up a non-trivial
amount of CPU time for a non-websocket based menchmark. This attempts
to speed it up.
Modifications:
- It is faster to check for a 101 response than to look at headers,
so an initial response code check is done
- Move all the actual upgrade code into its own method to increase
chance of this method being inlined
- Add an extra contains() check for the upgrade header, to avoid
allocating an iterator if there is no upgrade header
Result:
A small but noticable performance increase.
Signed-off-by: Stuart Douglas <stuart.w.douglas@gmail.com>