Native promises don't always work inside a transaction on Safari

[nbrustein]

I'm running into a case where, using a native promise inside of a transaction, I hit a TransactionInactiveError in Safari Desktop, but not Chrome or iOS Safari.

It's kind of difficult to come up with simple reproduction steps, though I can try to do so here if that would be helpful. Before I do that though, I wanted to ask about the comment on line 37 of this test file. The test is "Transaction should work when returning native Promise in transaction scope" and the comment says // Will only work on Chrome, Opera and Edge as of Oktober 6, 2016.)

Is there an undocumented issue with native promises inside browsers other than those listed there?

[nbrustein]

I also found this related issue but it seems to suggest that native promises should be working fine in Safari. Am I understanding that correctly?

[dfahlander]

They should work in Safari nowadays, and had for a few years. The particular test you reference is successfully run on every commit on a Safari 12.1 browser, using BrowserStack, so the comment is not valid for Safari anymore.

However I recall there was at some point, an issue in the very start of a transaction, before any operation had taken place, if in the then-handler of a resolved promise (one microtick has ran) the transaction could be gone. For example, if starting a transaction block with awaiting Promise.resolve("foo") before doing the initial operation, that has historically been a situation that had been a problem in idb transactions.

[bwindels]

I know it's been a while since this was filed, but have been looking into a very similar issue on Safari and managed to extract a test case to detect the bug. I've filed https://bugs.webkit.org/show_bug.cgi?id=222746. Thought it might be of interest, as this ticket was one of the few hits I got when looking for information about the bug.