fix: Add persistence for context to fix watchdog termination events

[philprime]

📜 Description

• Adds file persistence of the scope context to serialize for watchdog termination events

• Changes the watchdog termination scope observer as a collective entry point forwarding events to multiple processors to segment the logic into individual, testable components

• Refactors the existing breadcrumb persistence logic into a SentryWatchdogTerminationBreadcrumbProcessor. The implementation is not changed in this PR but prepared for future refactoring. A lot of the file operations are split with the SentryFileManager and would require more work.

• Adds a SentryWatchdogTerminationContextProcessor to process and persist the context to the file system. It uses the newly introduced `Sentry

• To not add even more logic to the SentryFileManager I added a wrapper store SentryScopeContextPersistentStore which handles encoding/decoding and file operations using the file manager.

• The SentryWatchdogTerminationContextProcessor is dispatching the saving via the persistent store on a background thread to reduce the impact on the main thread.

• The dispatch queue wrapper is created by the SentryDispatchFactory

In general I tried to bring a more constructor-based dependency injection style architecture into this PR, to make them replaceable and testable as individual units.

Originally the logic of SentryScopeContextPersistentStore was in the SentryWatchdogTerminationContextProcessor, therefore it's functionality is now slim and we could consider moving the method directly to the SentryWatchdogTerminationScopeObserver, but that would then. not match with the breadcrumb processor.

I believe the additional file is fine for now and can be refactored again at a future point.

💡 Motivation and Context

Closes #5182

💚 How did you test it?

📝 Checklist

You have to check all boxes before merging:

• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

Blocked by

• test: Add test target for SentryTestUtils with additional mock testing #5303
• fix: Add nullability to deserialization method #5313

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 194 lines in your changes missing coverage. Please review.

Project coverage is 9.134%. Comparing base (3851109) to head (054aadc).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ors/SentryWatchdogTerminationBreadcrumbProcessor.m	0.000%	55 Missing ⚠️
...ersistence/SentryScopeContextPersistentStore.swift	0.000%	46 Missing ⚠️
Sources/Sentry/SentryWatchdogTerminationTracker.m	0.000%	25 Missing ⚠️
Sources/Sentry/SentryDependencyContainer.m	0.000%	23 Missing ⚠️
...rs/SentryWatchdogTerminationContextProcessor.swift	0.000%	21 Missing ⚠️
...try/SentryWatchdogTerminationTrackingIntegration.m	0.000%	13 Missing ⚠️
...es/Sentry/SentryWatchdogTerminationScopeObserver.m	0.000%	7 Missing ⚠️
Sources/Sentry/SentryFileManager.m	0.000%	2 Missing ⚠️
Sources/Sentry/SentrySDK.m	0.000%	2 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (3851109) and HEAD (054aadc). Click for more details.

HEAD has 3 uploads less than BASE

Flag	BASE (3851109)	HEAD (054aadc)
	4	1

Additional details and impacted files

@@              Coverage Diff              @@
##              main    #5242        +/-   ##
=============================================
- Coverage   92.936%   9.134%   -83.802%     
=============================================
  Files          692      365       -327     
  Lines        86781    26647     -60134     
  Branches     31253      121     -31132     
=============================================
- Hits         80651     2434     -78217     
- Misses        6029    24213     +18184     
+ Partials       101        0       -101     

Files with missing lines	Coverage Δ
Sources/Sentry/SentryFileManager.m	18.348% <0.000%> (-75.803%)	⬇️
Sources/Sentry/SentrySDK.m	8.591% <0.000%> (-80.149%)	⬇️
...es/Sentry/SentryWatchdogTerminationScopeObserver.m	0.000% <0.000%> (-74.726%)	⬇️
...try/SentryWatchdogTerminationTrackingIntegration.m	0.000% <0.000%> (-84.375%)	⬇️
...rs/SentryWatchdogTerminationContextProcessor.swift	0.000% <0.000%> (ø)
Sources/Sentry/SentryDependencyContainer.m	41.290% <0.000%> (-48.647%)	⬇️
Sources/Sentry/SentryWatchdogTerminationTracker.m	0.000% <0.000%> (-100.000%)	⬇️
...ersistence/SentryScopeContextPersistentStore.swift	0.000% <0.000%> (ø)
...ors/SentryWatchdogTerminationBreadcrumbProcessor.m	0.000% <0.000%> (ø)

... and 676 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e2347a6...054aadc. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1209.27 ms	1239.76 ms	30.48 ms
Size	23.76 KiB	830.18 KiB	806.42 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
56ec5d0	1194.39 ms	1236.94 ms	42.55 ms
302ee8b	1194.02 ms	1223.34 ms	29.32 ms
9f0d9e0	1212.49 ms	1220.27 ms	7.78 ms
542727d	1227.96 ms	1246.88 ms	18.92 ms
bd05478	1233.82 ms	1255.56 ms	21.74 ms
c78683b	1255.78 ms	1261.94 ms	6.16 ms
f1b97be	1212.69 ms	1226.12 ms	13.43 ms
02a972c	1222.73 ms	1235.20 ms	12.47 ms
2d35ccb	1220.40 ms	1239.16 ms	18.77 ms
7192d9e	1221.86 ms	1248.28 ms	26.42 ms

App size

Revision	Plain	With Sentry	Diff
56ec5d0	20.76 KiB	414.44 KiB	393.68 KiB
302ee8b	20.76 KiB	419.62 KiB	398.87 KiB
9f0d9e0	21.58 KiB	424.28 KiB	402.70 KiB
542727d	21.58 KiB	571.85 KiB	550.26 KiB
bd05478	20.76 KiB	432.33 KiB	411.57 KiB
c78683b	20.76 KiB	435.24 KiB	414.47 KiB
f1b97be	21.58 KiB	681.73 KiB	660.15 KiB
02a972c	22.85 KiB	413.42 KiB	390.57 KiB
2d35ccb	21.58 KiB	705.96 KiB	684.38 KiB
7192d9e	20.76 KiB	431.71 KiB	410.95 KiB

Previous results on branch: philprime/issue-5182

Startup times

Revision	Plain	With Sentry	Diff
c9efa02	1229.42 ms	1251.57 ms	22.16 ms
9b69890	1244.68 ms	1258.16 ms	13.48 ms
69ce027	1232.45 ms	1251.65 ms	19.21 ms
35d6c88	1229.02 ms	1254.54 ms	25.52 ms
c5b273a	1212.13 ms	1235.94 ms	23.81 ms
bcd1b71	1217.71 ms	1229.96 ms	12.25 ms
c34e9ed	1223.86 ms	1249.84 ms	25.98 ms
278b49a	1221.16 ms	1246.98 ms	25.82 ms
496853a	1225.18 ms	1244.33 ms	19.15 ms
8c53c21	1223.46 ms	1246.42 ms	22.96 ms

App size

Revision	Plain	With Sentry	Diff
c9efa02	23.76 KiB	829.31 KiB	805.55 KiB
9b69890	23.76 KiB	874.87 KiB	851.11 KiB
69ce027	23.76 KiB	829.42 KiB	805.66 KiB
35d6c88	23.76 KiB	821.23 KiB	797.47 KiB
c5b273a	23.76 KiB	829.41 KiB	805.65 KiB
bcd1b71	23.76 KiB	829.42 KiB	805.66 KiB
c34e9ed	23.76 KiB	829.34 KiB	805.59 KiB
278b49a	23.76 KiB	829.80 KiB	806.04 KiB
496853a	23.76 KiB	830.09 KiB	806.33 KiB
8c53c21	23.76 KiB	829.42 KiB	805.66 KiB

[philprime]

This PR grew quite in size. I am now going to extract smaller PRs for necessary changes than can be seen as isolated changes (i.e. fixing compiler flags or serialization).

[github-actions]

🚨 Detected changes in high risk code 🚨

High-risk code can easily blow up and is hard to test. We had severe bugs in the past. Be extra careful when changing these files, and have an extra careful look at these:

• Sources/Sentry/SentryFileManager.m