fix: simplify dispatch queue wrapper access

[armcknight]

A possible solution to fix #3476. There are several places that we start a transaction with a tracer configuration that lacks a dispatch queue wrapper here:

sentry-cocoa/Sources/Sentry/SentryHub.m

Lines 358 to 365 in b9a9dca

	- (id<SentrySpan>)startTransactionWithContext:(SentryTransactionContext *)transactionContext
	bindToScope:(BOOL)bindToScope
	customSamplingContext:(NSDictionary<NSString *, id> *)customSamplingContext
	{
	return [self startTransactionWithContext:transactionContext
	bindToScope:bindToScope
	customSamplingContext:customSamplingContext
	configuration:[SentryTracerConfiguration defaultConfiguration]];

and here:

sentry-cocoa/Sources/Sentry/SentryPerformanceTracker.m

Lines 83 to 90 in b9a9dca

	newSpan = [SentrySDK.currentHub
	startTransactionWithContext:context
	bindToScope:bindToScope
	customSamplingContext:@{}
	configuration:[SentryTracerConfiguration configurationWithBlock:^(
	SentryTracerConfiguration *configuration) {
	configuration.waitForChildren = YES;
	}]];

In the spot where we do actually provide it here:

sentry-cocoa/Sources/Sentry/SentryUIEventTrackerTransactionMode.m

Lines 86 to 95 in b9a9dca

	transaction = [SentrySDK.currentHub
	startTransactionWithContext:context
	bindToScope:bindToScope
	customSamplingContext:@{}
	configuration:[SentryTracerConfiguration configurationWithBlock:^(
	SentryTracerConfiguration *config) {
	config.idleTimeout = self.idleTimeout;
	config.waitForChildren = YES;
	config.dispatchQueueWrapper = self.dispatchQueueWrapper;
	}]];

that reference is actually just set to the instance held by the dependency container here:

sentry-cocoa/Sources/Sentry/SentryUIEventTrackingIntegration.m

Lines 28 to 30 in b9a9dca

	SentryDependencyContainer *dependencies = [SentryDependencyContainer sharedInstance];
	SentryUIEventTrackerTransactionMode *mode = [[SentryUIEventTrackerTransactionMode alloc]
	initWithDispatchQueueWrapper:dependencies.dispatchQueueWrapper

I know we have an ongoing debate about when and where to use DI vs singletons, but let's avoid having this mixture, and take time to completely refactor one dependency at a time to remove the reference completely from SentryDependencyContainer convert to DI in all codepaths.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1201.65 ms	1213.20 ms	11.55 ms
Size	21.58 KiB	418.43 KiB	396.85 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
98a8c16	1234.69 ms	1265.02 ms	30.33 ms
591a01b	1197.94 ms	1222.53 ms	24.59 ms
98713e6	1211.48 ms	1244.42 ms	32.94 ms
01a28a9	1237.24 ms	1253.24 ms	16.00 ms
dd0557f	1246.31 ms	1258.46 ms	12.15 ms
2a894d5	1211.02 ms	1236.72 ms	25.70 ms
f576153	1217.17 ms	1225.06 ms	7.89 ms
17afc4b	1228.94 ms	1251.10 ms	22.16 ms
1bf8571	1250.96 ms	1255.36 ms	4.40 ms
c40576a	1202.45 ms	1224.60 ms	22.15 ms

App size

Revision	Plain	With Sentry	Diff
98a8c16	20.76 KiB	431.00 KiB	410.24 KiB
591a01b	22.84 KiB	401.67 KiB	378.83 KiB
98713e6	20.76 KiB	435.22 KiB	414.46 KiB
01a28a9	22.85 KiB	405.39 KiB	382.54 KiB
dd0557f	22.85 KiB	411.75 KiB	388.90 KiB
2a894d5	21.58 KiB	414.57 KiB	392.99 KiB
f576153	20.76 KiB	425.77 KiB	405.01 KiB
17afc4b	20.76 KiB	436.25 KiB	415.49 KiB
1bf8571	20.76 KiB	437.12 KiB	416.36 KiB
c40576a	22.85 KiB	407.63 KiB	384.78 KiB

Previous results on branch: armcknight/fix/3476-unscheduled-deadline-timer

Startup times

Revision	Plain	With Sentry	Diff
cca9946	1207.15 ms	1217.80 ms	10.65 ms
123eec4	1223.96 ms	1235.18 ms	11.22 ms
aead7e8	1219.10 ms	1246.33 ms	27.22 ms
619f72b	1217.63 ms	1241.55 ms	23.92 ms

App size

Revision	Plain	With Sentry	Diff
cca9946	21.58 KiB	418.43 KiB	396.85 KiB
123eec4	21.58 KiB	414.52 KiB	392.94 KiB
aead7e8	21.58 KiB	418.43 KiB	396.85 KiB
619f72b	21.58 KiB	418.21 KiB	396.62 KiB

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ea2a263) 89.214% compared to head (0158505) 89.227%.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3477       +/-   ##
=============================================
+ Coverage   89.214%   89.227%   +0.013%     
=============================================
  Files          528       528               
  Lines        57538     57552       +14     
  Branches     20617     20626        +9     
=============================================
+ Hits         51332     51352       +20     
+ Misses        5295      5291        -4     
+ Partials       911       909        -2     

Files	Coverage Δ
Sources/Sentry/SentryTracer.m	97.159% <100.000%> (+0.397%)	⬆️
...urces/Sentry/SentryUIEventTrackerTransactionMode.m	100.000% <ø> (ø)
Sources/Sentry/SentryUIEventTrackingIntegration.m	100.000% <100.000%> (ø)
...SentryProfilerTests/SentryProfilerSwiftTests.swift	97.769% <100.000%> (ø)
...iewController/SentryTimeToDisplayTrackerTest.swift	99.696% <100.000%> (ø)
...egrations/UIEvents/SentryUIEventTrackerTests.swift	100.000% <100.000%> (ø)
...ts/SentryTests/Transaction/SentryTracerTests.swift	98.858% <100.000%> (-0.008%)	⬇️

... and 12 files with indirect coverage changes

---

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[philipphofmann]

Good catch, @armcknight. Thanks for fixing this.

[philipphofmann]

LGTM, if you add a changelog entry @armcknight. You could also change the PR's title to reflect the user benefit instead of the detailed technical change.

[armcknight]

The thread sanitizer is in an unrelated test case, and failed recently on main: https://github.com/getsentry/sentry-cocoa/actions/runs/7263319984/job/19788493775#step:7:54