Add all validators as entrypoint to local cluster

[carllin]

Problem

When you have the following pattern:

1. Killing the entrypoint/leader
2. Kill validator A not the leader
3. Restarting validator A

Because the entrypoint is dead, validator A can't discover the cluster. Then that means A must have the same ports for gossip OR tvu as before the restart otherwise validator A won't be discoverable/receive any shreds from turbine.

Summary of Changes

Add all alive validators as entrypoints to A on restart so it's not dependent on only the initial entrypoint

Fixes #

[AshwinSekar]

saw some tests are failing here, might want to set the entry point to the node itself in case no one is alive (or single node cluster).

[carllin]

maybe this assertion is just not a good one then, since it's possible for a node to start up when everyone else is dead.

You're in a bind though if you restart by yourself with no entrypoints/outdated entrypoint and then the rest of the cluster boots up afterwards, you won't be able to be discovered by everybody else

Edit: I guess it's fine if everyone else adds you as an entrypoint though on startup

[AshwinSekar]

this should just work right - once the second validator starts up it will use the first guy as an entrypoint from the above collect?
Also do we want to update the LocalCluster 's entrypoint? previous code was doing this when restarting the entrypoint:

                self.entry_point_info = node.info.clone();

we could do this on restart if the previous entry point is dead? probably only useful for those tests that use rpc

[carllin]

yeah, that's a good catch, updating the entrypoint as was done previously

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.8%. Comparing base (2c11b7a) to head (b97d6cc).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master     #567     +/-   ##
=========================================
- Coverage    81.8%    81.8%   -0.1%     
=========================================
  Files         849      850      +1     
  Lines      229183   229369    +186     
=========================================
+ Hits       187585   187721    +136     
- Misses      41598    41648     +50