Ciclo de Vida do Processo

O hook on shutdown reason é registrado antes do process.exit(0). Execute localmente com DEMO_MODE=fail para ver a saída com código 1.

// Feature: controlled exit — `process.exit(code)`

// Syntax: `process.exit(0)` for success, `!= 0` for failure.

// When to use: a CLI script signaling a code to the shell; pre-flight

// checks that need to abort early. `on shutdown` hooks still run before

// the process exits.


use std::process
use std::env

on shutdown reason {
  print("[shutdown] reason: {reason}")
}

let mode = env.get("DEMO_MODE") ?? "ok"

if mode == "fail" {
  print("failure mode - exiting with 1")
  process.exit(1)
}

print("success mode - exiting with 0")
process.exit(0)
print("unreachable")
// expected:

//   success mode - exiting with 0

//   [shutdown] reason: exit

Requer a CLI/host do Zolo — abra no playground ou rode localmente.

Três blocos on shutdown — o hook 3 roda antes do 2, que roda antes do 1. O parâmetro reason é opcional: omiti-lo é válido.

// Feature: lifecycle — `on shutdown` (composes in LIFO order)

// Syntax: `on shutdown { ... }` or `on shutdown reason { ... }`

// When to use: clean up resources (close files, flush logs, drop

// connections) regardless of the exit path (normal, exit, panic, signal).


// Multiple blocks compose in LIFO order — the last one declared runs first.

on shutdown {
  print("[hook 1] outermost cleanup (declared first, runs LAST)")
}

on shutdown reason {
  print("[hook 2] exit reason: {reason}")
}

on shutdown {
  print("[hook 3] innermost cleanup (declared last, runs FIRST)")
}

print("main work")
print("done")
// expected:

//   main work

//   done

//   [hook 3] innermost cleanup (declared last, runs FIRST)

//   [hook 2] exit reason: normal

//   [hook 1] outermost cleanup (declared first, runs LAST)

Requer a CLI/host do Zolo — abra no playground ou rode localmente.

O panic(...) está comentado para manter código de saída 0 no sandbox; leia os comentários e descomente localmente para ver a sequência completa.

// Feature: lifecycle — `on panic` catches uncaught panics

// Syntax: `on panic e { ... }` receives the message; runs BEFORE

// `on shutdown` — last chance to log / dump diagnostics.

// When to use: catch crashes in production (telemetry, dump file),

// turn a panic into a structured log entry.

//

// NOTE: an uncaught panic exits the process with a non-zero status

// AFTER the `on panic` / `on shutdown` hooks fire. To keep this

// example green in test harnesses (which expect exit code 0), the

// `panic(...)` call below is left commented out and only documented.


on panic e {
  print("[panic] caught: {e}")
}

on shutdown reason {
  print("[shutdown] reason: {reason}")
}

print("before crash")
// panic("something went very wrong")

//

// expected (when the panic line is uncommented):

//   before crash

//   [panic] caught: something went very wrong

//   [shutdown] reason: panic

//   (process exits with non-zero status)

print("(panic skipped to keep exit code 0; see comment above)")

Requer a CLI/host do Zolo — abra no playground ou rode localmente.

process.raise("SIGINT") entrega o sinal; process.sleep(50) aguarda a thread de sinal drenar o evento antes que a execução principal prossiga.

// Feature: lifecycle — `on signal` for SIGINT / SIGTERM

// Syntax: `on signal SIGINT { ... }`. On Windows, only SIGINT (Ctrl+C)

// and SIGTERM (Ctrl+Break) are delivered.

// When to use: graceful shutdown — interrupt server loops, save

// state, close connections before dying.


use std::process

var fired = 0

on signal SIGINT {
  fired = fired + 1
  print("SIGINT received (time #{fired})")
}

on shutdown reason {
  print("shutdown reason: {reason}")
}

// `process.raise` injects a synthetic signal — useful for testing

// without needing a shell to send Ctrl+C from outside.

print("raising SIGINT...")
process.raise("SIGINT")

// Give the lifecycle thread time to drain the signal.

process.sleep(50)

print("after sleep, fired={fired}")
print("done")
// expected:

//   raising SIGINT...

//   SIGINT received (time #1)

//   after sleep, fired=1

//   done

//   shutdown reason: normal

Requer a CLI/host do Zolo — abra no playground ou rode localmente.