Bug 1647764 - Swift: Check and reset dirty flag on startup #1476
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badboy
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Feb 1, 2021
`applicationWillEnterForeground`[1] is posted _before_ the app is actually in the foreground, when it leaves the background stae. This notification is NOT posted on first app launch (because it doesn't leave a _background_ state). Therefore we previously triggered `handleForegroundEvent` in the constructor to work accordingly. That's not wrong for all current uses of Glean (I assume), but has two things worth pointing out: 1. It's different from Android behavior, where we do `handleForegroundEvent` only on an event (`ON_START`). 2. Because of that Android tests won't trigger `handleForegroundEvent` in unit tests, but only within a real app. We therefore can observe state after `Glean.initialize` but before `handleForegroundEvent`. We can't observe that currently in iOS. `didBecomeActiveNotification`[2] on the other hand is posted when the application is really active. It can be observed on first startup. Which should more closely match the behavior we also have on Android. See also #1476, which we are currently unable to test. We might be able to test it with this change. [1]: https://developer.apple.com/documentation/uikit/uiapplication/1622944-willenterforegroundnotification [2]: https://developer.apple.com/documentation/uikit/uiapplication/1622953-didbecomeactivenotification
mdboom
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Feb 1, 2021
This will avoid sending a dirty startup ping if the previous run of the application didn't successfully and completely initialize Glean. Unfortunately this is impossible to really test. Because we currently consider initialization as a "foreground notification" (for the lack of other signals) we immediately re-set the dirty flag to true. So once the `initialization` completes we can't observe the previous state anymore.
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This will avoid sending a dirty startup ping if the previous run of the application didn't
successfully and completely initialize Glean.
Unfortunately this is impossible to really test.
Because we currently consider initialization as a "foreground notification" (for the lack of other signals)
we immediately re-set the dirty flag to true.
So once the
initializationcompletes we can't observe the previousstate anymore.
@mdboom because he did the original implementation.
@travis79 for the Swift review.
I'm going to post another PR for discussion around the notifications shortly. Not gonna land this before we discussed that one.