The PeerAddressDB keeps a score for each IP/port we have about how
useful that peer is.
This change re-visits the way we use the DB where we now are more fluid
in our approach to scores. We no longer simply forever-ban a peer after
it made a mistake once.
This rewrites the select-a-peer algo to take timing into account,
preferring a peer that we connected to recently while putting a higher
score on a peer that failed a long time ago so if we start running out
of good peers we start on the not-so-great-but-maybe-improved first.
Good behavior is likewise rewarded so a peer can become higher prio
again, but generally a new IP still gets preferred. Again, the balance
is to keep not-so-great options in the running.
This avoids a peer once sending acceptable headers and never
being bothered again. Instead we now check regularly and keep
track of when the peer was known to follow the same chain as us.
The NetworkManager usage was mostly for low connection counts and this
made defaults selection easy.
With more usages it is important to allow the NWM-connection to be more
configurable about memory usage and leaner in general.
This changes the headers-buffers (used to create envelopes) to not be per
connection anymore but per thread using the tread_local keyword.
This changes the ring-buffers to become configurable using
NetworkConnections::setMessageQueueSizes().
Also removing some include statements where they were not really needed
in the P2PNet lib.
We reuse the NetworkManager lower level code in order to connect
to the Bitcoin P2P network.
This implements the basics for anyone wanting to be a player on
this network.
tomFlowee
TomZ