Instead of calculating all routes in one go, we calculate them when
needed.
Except for unicast routes, and broadcast routes from ourself. We still
calculate those eagerly because they are needed to route locally
captured/fdp-missed packets, and performing route calculcations in
that critical path increases the chances of dropping packets due to
not keeping up.
Well, technically only the established & symmetric routes are needed
for the data plane, but we might as well calculate the equivalent
routes for the control plane - it keeps the code simple and uniform.
Calculating all routes is O(n_peers^2), so this change represents a
huge saving in situations where not all of them are needed, which is
quite common, especially when the topology is evolving rapidly.
One downside of this new approach is that we can no longer suppress
OnChange callbacks when the data plane routes remain unchanged. This
means we will be purging the FDP flows more frequently than before,
e.g. when only the control plane topology changed, e.g. new
connections appeared that haven't been marked as 'established'
yet. It's a small price to pay, fixable if we really care, and in any
case making FDP flow invalidation more fine-grained would be a better
approach.
Fixes#1761.
This is more efficient since broadcasting about other peers is
strictly redundant. Any change to the peers will be broadcast by
those peers anyway. And SendAllGossipDown takes care of informing new
peers about others on first connect, and periodic gossip take care of
missed broadcasts.
The only reason we did broadcast about the remote peer is to reduce
the liklihood of UnknownPeerError and the associated throwing away of
gossip. This was always a bit of kludge, and is no longer necessary
since UnknownPeerError is gone.
Now peers only ever broadcast information about themselves. Which,
unlike information about other peers, is always authorative and most
up-to-date. Which is nice.
when encountering an unknown peer in received gossip, rather than
ignoring the entire gossip we create a placeholder Peer. This has
version 0 and uid 0, which means it will be replaced by any complete
peer information subsequently received via gossip.
We copy docker.sock owner to symlinks. Permissions are not copied,
because the permissions will inherit from the target.
use versioned exec image to create symlinks
Matthias Radestock