Add support for keep-alive-time parameter

[cescoffier]

The Netty variant of the gRPC server allows configuring the keep-alive-time. However, the Vert.x variant does not.

Related to: quarkusio/quarkus#36033

[vietj]

which keep alive are we talking about ? HTTP/2 ? it is not clear

[cescoffier]

In the NettyChannelBuilder, you have the io.grpc.netty.NettyChannelBuilder#keepAliveTime with the following javadoc:

Sets the time without read activity before sending a keepalive ping. An unreasonably small value might be increased, and Long.MAX_VALUE nano seconds or an unreasonably large value will disable keepalive. Defaults to infinite.
Clients must receive permission from the service owner before enabling this option. Keepalives can increase the load on services and are commonly "invisible" making it hard to notice when they are causing excessive load. Clients are strongly encouraged to use only as small of a value as necessary

Basically the time between pings.

Do we have the equivalent method in the pure Vert.x variant?

[vietj]

assuming HTTP/2 ping ?

[cescoffier]

Yes, Http/2 pings.

[vietj]

It seems that it periodically sends a ping HTTP/2 frame to the server to "keep alive" the stream. We could develop a similar feature for the new client on top of Vert.x HTTP/2 connection ping feature.

[vietj]

https://grpc.io/docs/guides/keepalive/