src/counter/counter.oxl

/// A counter per key: the state lives in the shard group of the key and survives the loss of a node.
pub actor Counter sharded by id: u64 {
  var total: i64 = 0
  on activate { print("counter {id} activated on {cluster.self().name}") }
  msg add(x: i64) -> i64 {
    total += x
    total
  }
  msg get() -> i64 { total }
}

pub(api) service Gate {
  @public rpc add(id: u64, x: i64) -> i64
  @public @readonly rpc get(id: u64) -> i64
}

impl Gate {
  rpc add(id, x) {
    match Counter(id).add(x) {
      i64 v => v
      NetError _ => -1
    }
  }
  rpc get(id) {
    match Counter(id).get() {
      i64 v => v
      NetError _ => -1
    }
  }
}

// `oxl dev` assigns the roles in order: edge first, the others store (OXL_ROLE overrides it).
cluster counters {
  role edge { serves Gate; runs leader("traffic"); replicas 1.. }
  role store { journal; shards 8; replication 3; hosts Counter }
  assign by env("OXL_ROLE") else auto
}