worker_pool.nula

// Dynamic worker pool — a simple_one_for_one OTP supervisor that spawns
// workers on demand from a single child template, driven from Nulang
// source via the built-in `Otp` effect.
//
// - `perform Otp.create_supervisor("name", strategy)` creates a supervisor
//   and returns its id; strategy is 0=one_for_one, 1=one_for_all,
//   2=rest_for_one, 3=simple_one_for_one.
// - `perform Otp.set_template(sup, "ActorTypeName")` sets the child
//   template of a simple_one_for_one supervisor.
// - `perform Otp.start_child(sup)` spawns a fresh worker from the
//   template and supervises it, returning the worker actor ref.
// - `perform Otp.terminate_child(sup, w)` retires a worker WITHOUT
//   restarting it; `perform Otp.child_count(sup)` counts live children.
//
// Dynamic children run under the Transient restart policy: an abnormal
// exit (like the `die` message below) restarts them from the template
// state defaults with a fresh actor id; a Normal exit or terminate_child
// retires them without a replacement.
//
// Run with: nulang examples/worker_pool.nula

actor PoolWorker {
    state count: Int = 0
    behavior work(x) { self.count = self.count + x }
    behavior die() { perform Actor.exit(1) }
}

fn main() {
    let sup = perform Otp.create_supervisor("pool", 3)
    let t = perform Otp.set_template(sup, "PoolWorker")
    let w1 = perform Otp.start_child(sup)
    let w2 = perform Otp.start_child(sup)
    w1 ! work(1)
    w2 ! work(2)
    // Crash w1: the supervisor restarts it from the template, so its
    // count goes back to 0 with a fresh actor id. w2 keeps its count.
    w1 ! die()
    0
}