Will a cloud function exit early if you don't use await on a nested function?

[Steven]

Hi,

I am wondering if a cloud function will exit early if I don't use await on a nested async function that (in this case) runs a firebase transaction?

The docs say that cloud functions won't end until all promises have returned something... So in theory just calling an async function (if I understand correctly async functions are wrapped in a promise by default) will always return a promise which means, even if I don't use await, the main function should not end until the async functions that are called inside of it return something...Regardless of whether or not await was used. 

Can anyone confirm if this is correct?

I've actually tested it and it works as expected, but I am not sure if that's only because the transactions run so fast they are done before the main function terminates and if for whatever reason the transaction is running slow one day will it be cancelled before it can run due to the parent function completing. 

[Hiranya Jayathilaka]

As long as you return a promise from the cloud function, it should be fine. For example:

async function someAsyncFunction(): Promise<string> {

  return "value";

}

functions.auth.user().onCreate(

  async (user, context) => {

    return someAsyncFunction(); // Returns Promise<string>; so this is ok

  });

If you want to catch errors from someAsyncFunction(), that's when you should think about return-awaiting:

functions.auth.user().onCreate(

  async (user, context) => {

    try {

      return await someAsyncFunction(); // Returns Promise<string>; await makes sure that the catch block is hit in the event of an error

    } catch (err) {

      return "error happened"; // will not reach, unless you await in the try block.

   }

  });

Hope this helps.

Thanks,

Hiranya

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Hiranya Jayathilaka | Software Engineer | h...@google.com | 650-203-0128