Dynamic dispatch forces heap allocation and adds extra overhead.
Dynamic casting as in the ones below, lacks compile-time type safety:
https://github.com/solana-labs/solana/blob/eeb622c4e/quic-client/src/lib.rs#L172-L175https://github.com/solana-labs/solana/blob/eeb622c4e/udp-client/src/lib.rs#L52-L55
The commit removes all instances of Any, Box<dyn ...>, and Arc<dyn ...>,
and instead uses generic and associated types.
There are only two protocols QUIC and UDP; and the code which has to
work with both protocols can use a trivial thin enum wrapper.
With respect to connection-cache specifically:
* connection-cache/ConnectionCache is a single protocol cache which
allows to use either QUIC or UDP without any build dependency on the
other protocol.
* client/ConnectionCache is an enum wrapper around both protocols and
can be used in the code which has to work with both QUIC and UDP.
Co-authored-by: Tyera Eulberg <tyera@solana.com>