fix: Crash in hasUnfinishedChildSpansToWaitFor

[philipphofmann]

📜 Description

Fix a crash in SentryTracer hasUnfinishedChildSpansToWaitFor by not setting the shouldIgnoreWaitForChildrenCallback to nil when finishing the tracer.

💡 Motivation and Context

Fixes GH-3781

💚 How did you test it?

Unit tests.

📝 Checklist

You have to check all boxes before merging:

• I reviewed the submitted code.
• 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.
• 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.

🔮 Next steps

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.854%. Comparing base (1ee3d54) to head (7e37fc8).

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3821       +/-   ##
=============================================
- Coverage   90.877%   90.854%   -0.024%     
=============================================
  Files          559       559               
  Lines        44054     44074       +20     
  Branches     15701     15689       -12     
=============================================
+ Hits         40035     40043        +8     
- Misses        3949      3961       +12     
  Partials        70        70               

Files	Coverage Δ
Sources/Sentry/SentryTracer.m	97.374% <ø> (+0.462%)	⬆️
...ts/SentryTests/Transaction/SentryTracerTests.swift	98.339% <100.000%> (+0.042%)	⬆️

... and 8 files with indirect coverage changes

---

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1222.82 ms	1237.29 ms	14.47 ms
Size	21.58 KiB	571.74 KiB	550.16 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
e0f077c	1224.65 ms	1243.52 ms	18.87 ms
e998fd0	1254.41 ms	1272.78 ms	18.37 ms
ecd9ecd	1214.16 ms	1232.59 ms	18.43 ms
9e6665f	1237.58 ms	1253.84 ms	16.26 ms
20163bb	1248.92 ms	1258.48 ms	9.56 ms
645f63f	1231.33 ms	1247.51 ms	16.18 ms
efb0147	1245.26 ms	1266.94 ms	21.68 ms
a6ac3d2	1219.00 ms	1231.32 ms	12.32 ms
39b1c35	1209.73 ms	1232.40 ms	22.67 ms
11ccc16	1203.82 ms	1237.06 ms	33.24 ms

App size

Revision	Plain	With Sentry	Diff
e0f077c	22.85 KiB	412.59 KiB	389.74 KiB
e998fd0	21.58 KiB	414.59 KiB	393.01 KiB
ecd9ecd	20.76 KiB	420.23 KiB	399.47 KiB
9e6665f	22.84 KiB	403.52 KiB	380.67 KiB
20163bb	20.76 KiB	426.82 KiB	406.06 KiB
645f63f	21.58 KiB	572.91 KiB	551.33 KiB
efb0147	22.84 KiB	403.52 KiB	380.67 KiB
a6ac3d2	20.76 KiB	436.65 KiB	415.89 KiB
39b1c35	22.85 KiB	408.88 KiB	386.03 KiB
11ccc16	20.76 KiB	431.71 KiB	410.95 KiB

[GuntisTreulands]

Hi!

I am using version 8.27.0, and got this crash once, again.

Please see the crash report: (changed extension to .txt to be able to upload)

1c860b0bf5824caeb44a0b24ad2446de-symbolicated.txt

Relevant parts:

Thread 15
0 libsystem_kernel.dylib 0x3b0ab761c __ulock_wait2
1 libsystem_platform.dylib 0x3d84974d8
2 libobjc.A.dylib 0x30e668e78 objc_sync_enter
3 Sentry 0x102ba397c -[SentryTracer finishInternal] (SentryTracer.m:585)
4 Sentry 0x102ba2784 -[SentryTracer spanFinished:] (SentryTracer.m:409)
5 Sentry 0x102ba7c6c -[SentrySpan finishWithStatus:] (SentrySpan.m:242)
6 Sentry 0x102bf3354 -[SentryCoreDataTracker managedObjectContext:executeFetchRequest:error:originalImp:] (SentryCoreDataTracker.m:62)
7 Sentry 0x102be2544 __42-[SentryCoreDataSwizzling swizzleCoreData]_block_invoke_2 (SentryCoreDataSwizzling.m:39)

Thread 0 Crashed:
0 Sentry 0x102ba31c4 -[SentryTracer hasUnfinishedChildSpansToWaitFor] (SentryTracer.m:502)
1 Sentry 0x102ba2df8 -[SentryTracer canBeFinished] (SentryTracer.m:470)
2 Sentry 0x102be0604 -[SentryPerformanceTracker finishSpan:withStatus:] (SentryPerformanceTracker.m:208)
3 Sentry 0x102bddd4c __102-[SentryUIViewControllerPerformanceTracker finishTransaction:status:lifecycleMethod:callbackToOrigin:]_block_invoke (SentryUIViewControllerPerformanceTracker.m:260)
4 Sentry 0x102bde4e8 -[SentryUIViewControllerPerformanceTracker limitOverride:target:callbackToOrigin:block:] (SentryUIViewControllerPerformanceTracker.m:378)
5 Sentry 0x102bddb8c -[SentryUIViewControllerPerformanceTracker finishTransaction:status:lifecycleMethod:callbackToOrigin:] (SentryUIViewControllerPerformanceTracker.m:266)
6 Sentry 0x102bdda80 -[SentryUIViewControllerPerformanceTracker viewControllerViewDidAppear:callbackToOrigin:] (SentryUIViewControllerPerformanceTracker.m:198)
7 Sentry 0x102bd6bcc __56-[SentryUIViewControllerSwizzling swizzleViewDidAppear:]_block_invoke_2 (SentryUIViewControllerSwizzling.m:395)

[philipphofmann]

@GuntisTreulands, please open an new issue for this referencing the PR.