Motivation:
If something is mis-configured, the "main" test will fail but it is unclear
whether it fails because the integration does not work or it wasn't applied
at all.
Also see:
https://github.com/netty/netty/issues/9738#issuecomment-548416693
Modifications:
This change adds a test that uses the same mechanism as BlockHound does
(`ServiceLoader`) and checks that `NettyBlockHoundIntegration` is present.
Result:
It is now clear whether the integration is not working or it wasn't loaded at all.
Motivation:
Netty is an asynchronous framework.
If somebody uses a blocking call inside Netty's event loops,
it may lead to a severe performance degradation.
BlockHound is a tool that helps detecting such calls.
Modifications:
This change adds a BlockHound's SPI integration that marks
threads created by Netty (`FastThreadLocalThread`s) as non-blocking.
It also marks some of Netty's internal methods as whitelisted
as they are required to run the event loops.
Result:
When BlockHound is installed, any blocking call inside event loops
is intercepted and reported (by default an error will be thrown).
