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DeviceCache: removed fatalError for users not overriding UserDefaults #2079

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merged 1 commit into from
Nov 22, 2022

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@NachoSoto NachoSoto commented Nov 22, 2022

We can do this now thanks to #2046. Solves #1906.
We no longer need to do this check if we're using our own UserDefaults, which simplifies the code, avoids a dangerous fatalError, and makes CSDK-519 less likely.

@NachoSoto NachoSoto added the perf label Nov 22, 2022
@NachoSoto NachoSoto requested review from aboedo and a team November 22, 2022 21:38
Base automatically changed from device-cache-synchronous-user-defaults-observation to main November 22, 2022 21:39
…aults`

We can do this now thanks to #2046. Solves #1906.
We no longer need to do this check if we're using our own `UserDefaults`, which simplifies the code, avoids a dangerous `fatalError`, and makes [CSDK-519] less likely.
@NachoSoto NachoSoto force-pushed the device-cache-remove-fatal-error branch from 50cbee6 to 3dce90f Compare November 22, 2022 21:42
Comment on lines +62 to +64
// leave it in an undetermined state. See https://rev.cat/userdefaults-crash
// If the user is not using a custom `UserDefaults`, we don't need to
// because they have no access to it.
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the good news is that folks who are setting their custom user defaults for revenuecat usually know not to delete its contents, so the code will likely very rarely run

@NachoSoto NachoSoto enabled auto-merge (squash) November 22, 2022 21:50
@NachoSoto NachoSoto merged commit e5d7293 into main Nov 22, 2022
@NachoSoto NachoSoto deleted the device-cache-remove-fatal-error branch November 22, 2022 21:50
NachoSoto added a commit that referenced this pull request Nov 23, 2022
**This is an automatic release.**

### Bugfixes
* Changed default `UserDefaults` from `.standard` to our own Suite
(#2046) via NachoSoto (@NachoSoto)
### Other Changes
* `Logging`: added log when configuring SDK in observer mode (#2065) via
NachoSoto (@NachoSoto)
* `PurchaseTesterSwiftUI`: added observer mode setting (#2052) via
NachoSoto (@NachoSoto)
* Exposed `SystemInfo.observerMode` to simplify code (#2064) via
NachoSoto (@NachoSoto)
* `Result.init(catching:)` with `async` method (#2060) via NachoSoto
(@NachoSoto)
* Updated schemes and project for Xcode 14.1 (#2081) via NachoSoto
(@NachoSoto)
* `PurchasesSubscriberAttributesTests`: simplified tests (#2056) via
NachoSoto (@NachoSoto)
* `DeviceCache`: removed `fatalError` for users not overriding
`UserDefaults` (#2079) via NachoSoto (@NachoSoto)
* `DeviceCache`: changed `NotificationCenter` observation to be received
on posting thread (#2078) via NachoSoto (@NachoSoto)
* `StoreKit1Wrapper`: added instance address when detecting transactions
(#2055) via NachoSoto (@NachoSoto)
* Fixed lint issues with `SwiftLint 0.5.0` (#2076) via NachoSoto
(@NachoSoto)
* `NSData+RCExtensionsTests`: improved errors (#2043) via NachoSoto
(@NachoSoto)
* `APITester`: fixed warning in `SubscriptionPeriodAPI` (#2054) via
NachoSoto (@NachoSoto)
* `Integration Tests`: always run them in random order locally (#2068)
via NachoSoto (@NachoSoto)

Co-authored-by: NachoSoto <ignaciosoto90@gmail.com>
NachoSoto added a commit that referenced this pull request Mar 24, 2023
Fixes #2252, #2364, RevenueCat/react-native-purchases#579, [SDKONCALL-214], [SDKONCALL-238], [SDKONCALL-241].
See also #2078 and #2079.

### Background

#2078 solved a potential deadlock in `DeviceCache`. This could happen when a background thread was in the middle of writing to `UserDefaults` through `DeviceCache`, and at the same time, the main thread wanted to read from it.
This is normally fine, except that if there are any `NotificationCenter` observations on the `UserDefaults` used, the background thread would then post that notification and wait for the main thread, leading to a deadlock. What #2078 did was to use a different method to make sure that the observation was received in the calling thread.
Additionally, #2079 avoided that observation whenever we used a different `UserDefaults`.

### Problem

When the SDK changed to a custom `UserDefaults` (#2046), we made the choice to only do this if there was no prior data.
However, if an app has prior RevenueCat data saved in `UserDefaults.standard`, that instance is used.

This potential deadlock is possible for any app with prior data, that also contains observations to `UserDefaults`, either manually through `NotificationCenter`, or using something like `@AppStorage` with `SwiftUI`.

### Solution

`DeviceCache.cachedAppUserID` is a very commonly used method. This PR changes it to an in-memory cache, initialized to the `UserDefaults` value.
By doing that, most code paths that rely on this value won't risk deadlocking with `UserDefaults` writes that jump threads.

### Long term

I've filed SDK-3034 to fully migrate data from `UserDefaults.standard` to avoid this problem altogether in the future.
NachoSoto added a commit that referenced this pull request Mar 24, 2023
Fixes #2252, #2364, RevenueCat/react-native-purchases#579, [SDKONCALL-214], [SDKONCALL-238], [SDKONCALL-241].
See also #2078 and #2079.

### Background

#2078 solved a potential deadlock in `DeviceCache`. This could happen when a background thread was in the middle of writing to `UserDefaults` through `DeviceCache`, and at the same time, the main thread wanted to read from it.
This is normally fine, except that if there are any `NotificationCenter` observations on the `UserDefaults` used, the background thread would then post that notification and wait for the main thread, leading to a deadlock. What #2078 did was to use a different method to make sure that the observation was received in the calling thread.
Additionally, #2079 avoided that observation whenever we used a different `UserDefaults`.

### Problem

When the SDK changed to a custom `UserDefaults` (#2046), we made the choice to only do this if there was no prior data.
However, if an app has prior RevenueCat data saved in `UserDefaults.standard`, that instance is used.

This potential deadlock is possible for any app with prior data, that also contains observations to `UserDefaults`, either manually through `NotificationCenter`, or using something like `@AppStorage` with `SwiftUI`.

### Solution

`DeviceCache.cachedAppUserID` is a very commonly used method. This PR changes it to an in-memory cache, initialized to the `UserDefaults` value.
By doing that, most code paths that rely on this value won't risk deadlocking with `UserDefaults` writes that jump threads.

### Long term

I've filed SDK-3034 to fully migrate data from `UserDefaults.standard` to avoid this problem altogether in the future.
NachoSoto added a commit that referenced this pull request Mar 24, 2023
Fixes #2252, #2364, [SDKONCALL-214], [SDKONCALL-241].
See also #2078 and #2079.

### Background

#2078 solved a potential deadlock in `DeviceCache`. This could happen
when a background thread was in the middle of writing to `UserDefaults`
through `DeviceCache`, and at the same time, the main thread wanted to
read from it.
This is normally fine, except that if there are any `NotificationCenter`
observations on the `UserDefaults` used, the background thread would
then post that notification and wait for the main thread, leading to a
deadlock. What #2078 did was to use a different method to make sure that
the observation was received in the calling thread.
Additionally, #2079 avoided that observation whenever we used a
different `UserDefaults`.

### Problem

When the SDK changed to a custom `UserDefaults` (#2046), we made the
choice to only do this if there was no prior data.
However, if an app has prior RevenueCat data saved in
`UserDefaults.standard`, that instance is used.

This potential deadlock is possible for any app with prior data, that
also contains observations to `UserDefaults`, either manually through
`NotificationCenter`, or using something like `@AppStorage` with
`SwiftUI`.

### Solution

`DeviceCache.cachedAppUserID` is a very commonly used method. This PR
changes it to an in-memory cache, initialized to the `UserDefaults`
value.
By doing that, most code paths that rely on this value won't risk
deadlocking with `UserDefaults` writes that jump threads.

### Long term

I've filed SDK-3034 to fully migrate data from `UserDefaults.standard`
to avoid this problem altogether in the future.


[SDKONCALL-214]:
https://revenuecats.atlassian.net/browse/SDKONCALL-214?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ
[SDKONCALL-238]:
https://revenuecats.atlassian.net/browse/SDKONCALL-238?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ
[SDKONCALL-241]:
https://revenuecats.atlassian.net/browse/SDKONCALL-241?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ
NachoSoto added a commit that referenced this pull request Apr 10, 2023
Fixes #2252, #2364, [SDKONCALL-214], [SDKONCALL-241].
See also #2078 and #2079.

when a background thread was in the middle of writing to `UserDefaults`
through `DeviceCache`, and at the same time, the main thread wanted to
read from it.
This is normally fine, except that if there are any `NotificationCenter`
observations on the `UserDefaults` used, the background thread would
then post that notification and wait for the main thread, leading to a
deadlock. What #2078 did was to use a different method to make sure that
the observation was received in the calling thread.
Additionally, #2079 avoided that observation whenever we used a
different `UserDefaults`.

When the SDK changed to a custom `UserDefaults` (#2046), we made the
choice to only do this if there was no prior data.
However, if an app has prior RevenueCat data saved in
`UserDefaults.standard`, that instance is used.

This potential deadlock is possible for any app with prior data, that
also contains observations to `UserDefaults`, either manually through
`NotificationCenter`, or using something like `@AppStorage` with
`SwiftUI`.

`DeviceCache.cachedAppUserID` is a very commonly used method. This PR
changes it to an in-memory cache, initialized to the `UserDefaults`
value.
By doing that, most code paths that rely on this value won't risk
deadlocking with `UserDefaults` writes that jump threads.

I've filed SDK-3034 to fully migrate data from `UserDefaults.standard`
to avoid this problem altogether in the future.

[SDKONCALL-214]:
https://revenuecats.atlassian.net/browse/SDKONCALL-214?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ
[SDKONCALL-238]:
https://revenuecats.atlassian.net/browse/SDKONCALL-238?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ
[SDKONCALL-241]:
https://revenuecats.atlassian.net/browse/SDKONCALL-241?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ
@vegaro vegaro added pr:other and removed pr:perf labels Sep 17, 2024
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