Allow Errors in Queue Tasks to reject Promise #7
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EricByers
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November 17, 2015 23:00
…rn in the correct order. Fixing tests that incorrectly accounted for offset (ie 10 items added, expected 10 after first item complete)
…xception when it is the second item in the queue (to make sure it is triggered form the dequeue and not the add, and one for promise handling order after exception is thrown
azproduction
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Nov 24, 2015
Allow Errors in Queue Tasks to reject Promise
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Hey, thank you for the pull request! Sorry that it took so much time to review! |
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Since some promise libraries automatically convert an exception into a rejection, and because the promise returned from the queue is not the same one that is used by the queue management, it was causing the exception to be completely dropped.
First attempt to fix this was adding a second
thenhandler, which worked, however caused a couple of new issues, because the rejection is handled in the calling context, the item that is rejected is the previous queue item. Getting the next queue item looks to be complex and would potentially have issues with queues that run more than 1 item at a time.So since promises already essentially wrap a try catch, we wrap this around the main calling stack in dequeue, this allows the exception to be handled in the same stack it was thrown in, everything gets called in the correct order. This should mean the try/catch example in the README is no longer needed as it will handle it internally automatically and pass it to the reject, instead of only try/catching only when the queue was empty when it was added.
This should resolve the issue in #6