vl3 healing

[NikitaSkrynnik]

Proposal

vl3 network doesn't have healing. We can't use original healing in this case because when one vl3 endpoint dies, a new vl3 endpoint automatically reconnects to all other vl3 NSEs when it's created.

For vl3 networks we only need to cleanup resources when vl3 endpoints die.

There are two main cases:

1. Client-side of the connection dies

In this case we have timeout chain element that will eventually close the connection from the dead vl3 NSE.

2. Server-side of the connection dies

In this case we get the leaked connection because client doesn't close it.

Therefore, we need a client chain element that closes connections to the dead vl3 NSEs.

Solution

Create a client chain element that monitors NSEs to which it has a connection. If it gets deleted:true event from the registry for any of these NSEs it should automatically Close the client-side of the connections to the deleted vl3 NSE.