Baby

Bushbaby Automated Bamboo Yields

Sync for Bamboo stores using the Bushbaby protocol

Connection tuning

The per-connection idle timeout is governed by four settings, all read from Application config (config :baby, ...) at connection startup, and overridable per-connection:

• :outrate — milliseconds between outbox ticks. Default: a random prime near 75 (jittered so connections don't tick in lockstep).
• :handshake_spins — idle budget, in outbox intervals, before a valid HELLO has been received. A connection that never proves itself is dropped quickly so an anonymous flood cannot pin the listener's connection slots. Default: a random prime near 375 (~30s at the default outrate).
• :max_spins — idle budget, in outbox intervals, once the initial replication sync has completed. Default: a random prime near 1200.
• :bootstrap_spins — idle budget while the initial sync is still in progress, giving the peer time to compute its WANT list before being dropped. Default: a random prime near 3000.

The idle counter resets on any send or receive, so the budgets measure consecutive silence rather than wall-clock time on a busy link. A connection that exceeds its budget is dropped and re-established on the next cryout.

To estimate wall-clock time, multiply the budget by :outrate — e.g. a default max_spins of ~1193 at a default outrate of ~80ms is roughly 95 seconds, and a default bootstrap_spins of ~2969 is roughly 4 minutes.

config :baby,
  outrate: 100,
  handshake_spins: 375,
  max_spins: 1200,
  bootstrap_spins: 5000

Wire buffer

Inbound bytes that have not yet formed a complete protocol frame are buffered in the connection's wire state. A peer that dribbles undecodable bytes could otherwise grow this buffer without bound, so it is capped:

• :wire_cap — maximum buffered bytes per connection before the connection is dropped. Read from Application config (config :baby, wire_cap: ...) at connection startup, overridable per-connection. Default: 32MB.

The cap sits comfortably above the largest legitimate frame (a single message may carry an entire log), so it should only trip for garbage; note the protocol spec guidance on authoring log entries that fit within peers' limits.

Listener

The ranch listener that accepts peer connections has a deliberate ceiling on concurrent connections, so a flood of anonymous connections cannot exhaust file descriptors or slot-bound the legitimate peer:

• :max_connections — maximum concurrent connections accepted per listener. Read from Application config (config :baby, max_connections: ...) at startup, overridable per-clump. Default: 256 (ranch's own default is 1024).

config :baby, max_connections: 256

Local network discovery (mDNS)

Clumps can advertise themselves to peers on the local network and can find those peers without statically configured addresses. This is built on mdns_lite, which is started automatically when any clump needs it. Services are advertised as standard _bushbaby._tcp DNS-SD records whose TXT payload carries the announcing clump's clump_id, so they are visible to any mDNS tooling (dns-sd, Avahi, etc.), not just other Baby nodes.

Per-clump configuration (config :baby, clumps: [...]):

• announce — true advertises this clump's listener via mDNS; a keyword list of Baby.Mdns.announce/3 options (e.g. instance:) customizes the advertisement. Default: false.
• Within a cryouts entry, mdns: — true (or keyword options) turns that cryout into a "meta cryout": instead of dialing a fixed {host, port}, the monitor periodically browses the local network and connects to every discovered peer of the same clump it isn't already talking to. A period may be given either at the cryout's top level or inside the mdns options; unconfigured meta cryouts cycle about once a minute (a random prime number of seconds near 60, so many peers do not browse in lockstep), while fixed-host cryouts default to {17, :minute}.

config :baby,
  clumps: [
    [
      id: "Quagga",
      controlling_identity: my_identity,
      port: 8483,
      announce: true,
      cryouts: [[mdns: [period: {5, :minute}]]]
    ]
  ]

Because discovery re-runs on every meta-cryout cycle, clump-mates that come and go are picked up (and re-dialed) automatically, exactly as fixed-host cryouts re-establish dropped connections.