Global _signinPromise means only one method call can happen at a time

[esprehn]

Global _signinPromise Promise means that you can never call multiple methods at the same time. I think you want to use a final variable that's a wrapper around the Promise variable that you can then use inside the callbacks. This can happen for example if two parts of the code call currentUserAsync() at the same time. Only one will get a reply.

Note that you must not resolve promises more than once even though that's fine in JS since RN's Java Promise is implemented wrong: facebook/react-native#20262

Something like:

class PromiseResolver {
  Promise promise;
  PromiseResolver(Promise promise) {
    this.promise = promise;
  }
  resolve(Object value) {
     if (!promise) return;
    promise.resolve(value);
    promise = null;
  }
  reject(String code, String message) {
     if (!promise) return;
    promise.reject(code, message);
    promise = null;
  }
}

and then inside each method like configure(ReadableMap config, Promise promise) or signOut(Promise promise) you'd do:

final PromiseResolver resolver = new PromiseResolver(promise);

and use that resolver inside the Runnable on the UI thread. signIn() is the only one with an activityResult where you need to use a global. For that I'd suggest rejecting if a duplicate request comes in so no one is ever left hanging. So at the top of signIn() you'd have:

  if (_signInResolver) {
   promise.reject(MODULE_NAME, "Already doing signin.")
   return;
  }

Steps to Reproduce

GoogleSignIn.currentUserAsync().then(user => console.log(1, user));
GoogleSignIn.currentUserAsync().then(user => console.log(2, user));

It'll only log once the 2 because the global _signinPromise is overridden.

Expected Behavior

Can make multiple calls to methods like currentUserAsync() at the same time.

Actual Behavior

Only the last method call on the entire module ever gets a response.

Environment

n/a.

[jozan]

Thanks for reporting! We've addressed this problem in #459. It's on master now but all those changes are not properly documented, yet. This will be included in to the next release!