969318 - "A promise chain failed to handle a rejection" from the livemarks service (deprecate passing a callback)

Status: RESOLVED FIXED

(Toolkit :: Places, defect)

Description

[Marco Bonardo [:mak]]

The livemarks service is now accepting both callbacks and returning a promise, the problem is that consumers using the callback are not handling the promise, so when we reject it an error is printed to the error console stating "A promise chain failed to handle a rejection".

There are some possibilities here:
1. add at least one internal handler
Yoric suggested
promise.then(null, () => undefined); // Ensure that there is at least one consumer for this error

2. return the promise only if a callback is not provided

3. split the promise and the callback APIs

4. bug 896186 keep only the promise api and break all consumers

Comment 1

[Marco Bonardo [:mak]]

4. could even be done with a mozIAsyncLivemarks compatible shim (that only gets the callback)

Comment 2

[David Teller [:Yoric] - still alive but not very active]

Note that option 1. is actually

let promise = ...;
promise.then(null, () => undefined); // Ensure that there is at least one consumer for this error
return promise; // However, if anybody else does promise.then(), they will get the uncaught error warning

Comment 3

[Marco Bonardo [:mak]]

I think the best option for now is 2 (short term) followed by 4 (long term)
Mano, what do you think?

Comment 6

[Marco Bonardo [:mak]]

I'll go for option 2 and ask for review

Comment 7

[Marco Bonardo [:mak]]

Attachment: patch v1

It's mostly "automatic" refactoring to convert callbacks to .then, and I added the deprecate warnings.
From here converting the service to a module should be straight forward, we may then keep the service as a shim wrapping the module, for some releases.

Comment 8

[Asaf Romano (gone)]

Comment on attachment 8386367 [details] [diff] [review]
patch v1

Many many thanks for taking care of converting the consumers.

Comment 9

[Marco Bonardo [:mak]]

https://hg.mozilla.org/integration/fx-team/rev/60c1af78091a

Comment 10

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/60c1af78091a