support waiting on multiple events in step

[oieduardorabelo]

ref this 2024 issue: #1315 (comment)

@jpwilliams suggested a user-land solution by managing Promises

a common scenario for me is waiting on ack of success or fail of a 3rd service webhooks, like:

const twilioWhatsApp = await step.invoke("whatsapp-send", ...)

await Promise.race([
  step.waitForEvent("whatsapp-reply", {
    event: "whatsapp_reply",
    timeout: TIMEOUT_MAX,
    if: `"${event.data.id}" == async.data.id && "${event.data.target}" == async.data.target`,
  }),
  step.waitForEvent("twilio-outbound-failed", {
    event: "twilio/outbound_failed",
    timeout: TIMEOUT_MAX,
    if: `"${twilioWhatsApp.sid}" == async.data.MessageSid`,
  }),
]);

i'm curious about what's the official suggestion from inngest team?

[jpwilliams]

Hi @oieduardorabelo - I'll answer your question in #315 here!

You can totally use Promise.race() too! Using the waitForAny() I suggested in the other thread does give Inngest the chance to optimize the execution of that function a little, as Promise.race() requires that we're revisiting your function as often as we can.

In addition, if in this case you had differing timeouts, the waitForAny() snippet wouldn't resolve early, though with if you had a race with a 10s and a 20s timeout and the 10s timed out, that'd resolve with null.

It's small differences really; if you're happy with aligning timeouts then it's basically the same!