writeonce/tests/corpus/run/mailbox-full-trap/fixture.wo

use time

-- iteration 24: fail-fast backpressure from .wo. The sleeper parks in its
-- first receive, so the mailbox only ever drains by one; a send loop must
-- hit the cap (default 1024) and catch WO_T_ACTOR. The exact send count
-- at the first trap depends on scheduling, so the fixture prints the
-- trap's message once plus a bound check, never the count. `try` is an
-- expression, so the send is wrapped in a helper whose success is nil.
class Tick {
  n: Int
}

class Sleeper {
  fn receive(msg: Tick) {
    time.sleep(5000);
  }
}

fn send_one(s: actor Tick, n: Int) -> Text {
  send(s, Tick { n: n });
  return "";
}

fn main() -> Int {
  let s: actor Tick = spawn Sleeper {};
  let sent = 0;
  let caught = "";
  let i = 0;
  while i < 2000 {
    i = i + 1;
    let r = try send_one(s, i) catch (e) e.msg;
    if r == "" {
      sent = sent + 1;
    } else {
      caught = "${r}";
      i = 2000;
    }
  }
  if caught == "actor mailbox full" {
    print("trap: ${caught}");
  } else {
    print("NO TRAP after ${sent} sends");
  }
  if sent >= 1024 {
    print("bounded: cap respected");
  } else {
    print("bounded: TRAPPED EARLY at ${sent}");
  }
  return 0;
}