1230623 - Close our database connections in applicationWillTerminate

Status: RESOLVED FIXED

(Firefox for iOS :: Data Storage, defect)

Description

[Richard Newman [:rnewman]]

The belt-and-braces part of Bug 1230288.

Potential follow-up from Bug 1228611 Comment 2.

Comment 1

[Richard Newman [:rnewman]]

We can fake an applicationWillTerminate by backgrounding the app with UIApplicationExitsOnSuspend = YES in Info.plist.

That gives us a little bit of out-of-order stuff -- our usual backgrounding code runs -- but it still works:

In normal operation aWT is called much later, so this is fine.

[DEBUG] Did enter background
[DEBUG] Did close IPv6 listening socket 8
[DEBUG] Did close IPv4 listening socket 7
[INFO] GCDWebServer stopped
2015-12-04 10:39:02.096 [Debug] [AppDelegate.swift:134] applicationWillTerminate > Application will terminate.
2015-12-04 10:39:02.116 [Debug] [Profile.swift:244] shutdown() > Shutting down profile.
2015-12-04 10:39:02.127 [Debug] [SwiftData.swift:424] deinit > deinit: closing connection on thread <NSThread: 0x12c61ade0>{number = 1, name = main}.
2015-12-04 10:39:02.135 [Debug] [SwiftData.swift:487] closeCustomConnection(immediately:) > Closing custom connection for /private/var/mobile/Containers/Shared/AppGroup/A84FCE11-91C9-4074-A0FC-5B72AC829F34/profile.profile/browser.db on <NSThread: 0x12c61ade0>{number = 1, name = main}.
2015-12-04 10:39:02.144 [Debug] [Profile.swift:237] background() > Backgrounding profile.
2015-12-04 10:39:02.149 [Debug] [SwiftData.swift:507] closeCustomConnection(immediately:) > Closed /private/var/mobile/Containers/Shared/AppGroup/A84FCE11-91C9-4074-A0FC-5B72AC829F34/profile.profile/browser.db.
2015-12-04 10:39:02.158 [Debug] [Profile.swift:226] logProfileFDs() > Open file descriptors:

Comment 2

[Richard Newman [:rnewman]]

Sorry, clearer logs without uncommitted code!

2015-12-04 10:44:24.849 [Debug] [Profile.swift:902] syncEverythingSoon() > Running delayed startup sync.
2015-12-04 10:44:25.009 [Warning] [Profile.swift:858] withSyncInputs(_:function:) > No account; can't sync.
2015-12-04 10:44:25.559 [Debug] [Profile.swift:770] endTimedSyncs() > Stopping sync timer.
[DEBUG] Did enter background
[DEBUG] Did close IPv6 listening socket 8
[DEBUG] Did close IPv4 listening socket 7
[INFO] GCDWebServer stopped
2015-12-04 10:44:25.589 [Debug] [Profile.swift:224] shutdown() > Shutting down profile.
2015-12-04 10:44:25.598 [Debug] [SwiftData.swift:424] deinit > deinit: closing connection on thread <NSThread: 0x157d31300>{number = 6, name = (null)}.
2015-12-04 10:44:25.609 [Debug] [AppDelegate.swift:134] applicationWillTerminate > Application will terminate.
2015-12-04 10:44:25.616 [Debug] [Profile.swift:224] shutdown() > Shutting down profile.

Comment 3

[Richard Newman [:rnewman]]

Attachment: Link to Github pull-request: https://github.com/mozilla/firefox-ios/pull/1341

Comment 4

[Richard Newman [:rnewman]]

master: edb7d40

Any strong opinions about uplifting this?

Comment 5

[Aaron Train [:aaronmt]]

No strong opinions, only questions. 

Will iOS call applicationWillTerminate just before device shutdown on battery depletion?

Comment 6

[Richard Newman [:rnewman]]

That's pretty much the only purpose of applicationWillTerminate in iOS4+: if the app is in the foreground and is about to be terminated.

Otherwise we get an equivalent notification for entering the background.

Apparently aWT t can be called when we're recently backgrounded but need to be terminated (memory pressure?), but I don't know the precise circumstances.

Comment 7

[Stefan Arentz | :st3fan | ⏰ EST | he/him]

I don't think the circumstances are spelled out, but memory pressure is probably the main reason. THe docs say we do get 5 seconds to clean up in applicationWillTerminate: