feat: append launch profile data to app start transactions/spans

[armcknight]

Following on app launch profiling that only used a dedicated span to attach the profiles, we will now attach the profile data to an automatic app start transaction if one will be recorded, otherwise continue with the same dedicated txn.

Closes #3725

Changes

• Change SentrySDK.startWithOptions from always stopping the launch profile to only stopping it if SentryUIViewControllerPerformanceTracker.shared.enableWaitForFullDisplay is NO, otherwise, that trace will eventually end and get all the profile data. Then, SentryTimeToDisplayTracker will call stopLaunchProfile passing nil as the hub argument which will stop the dedicated tracer without actually sending a duplicate dedicated transaction, since the profile data we previously attached to it is now on the app start txn.
• Records the system time SentrySysctl.load is called and keeps that as the runtimeInitSystemTimestamp to report to SentryAppStartMeasurement, which is used when SentryTracer requests a slice of profile data to attach to the app start transaction. Profile slicing needs a system timestamp which it uses to keep relevant samples and compute relative timestamps. it's set as the SentryTransaction.startSystemTime for app start transactions.
• We no longer need to keep track of originalStartTimestamp in SentryTracer. We now take either the actual start time of the tracer (which was always the case outside of app start transactions, which modifies SentryTracer.startTimestamp) or SentryAppStartMeasurement.runtimeInitTimestamp in the case of app start txns, since this corresponds to the time that we're recording SentrySysctl.processStartSystemTimestamp as mentioned above.
  • Note that for prewarmed launches, we don't record a span using runtimeInitTimestamp. But, we have no reliable way to test what will happen for these launch types, so we are going to postpone any further treatment of that edge case.

Before (the profile data starts at the extreme right end):

After:

[github-actions]

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## Unreleased

- append launch profile data to app start transactions/spans ([#3736](https://github.com/getsentry/sentry-cocoa/pull/3736))

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Generated by 🚫 dangerJS against b34fe84

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1241.53 ms	1251.67 ms	10.14 ms
Size	21.58 KiB	548.09 KiB	526.50 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
7054676	1229.46 ms	1246.40 ms	16.94 ms
861d361	1227.90 ms	1231.45 ms	3.55 ms
01a28a9	1237.78 ms	1259.04 ms	21.27 ms
72c8d84	1218.69 ms	1241.08 ms	22.39 ms
282cc99	1232.59 ms	1245.88 ms	13.29 ms
d0deebd	1235.17 ms	1255.54 ms	20.37 ms
c2acec5	1243.04 ms	1254.15 ms	11.10 ms
8c50edb	1212.98 ms	1233.72 ms	20.74 ms
ecd9ecd	1215.77 ms	1238.70 ms	22.93 ms
7cd187e	1243.04 ms	1244.79 ms	1.75 ms

App size

Revision	Plain	With Sentry	Diff
7054676	21.58 KiB	542.28 KiB	520.70 KiB
861d361	20.76 KiB	435.65 KiB	414.89 KiB
01a28a9	22.85 KiB	405.39 KiB	382.54 KiB
72c8d84	22.85 KiB	408.88 KiB	386.03 KiB
282cc99	22.85 KiB	414.09 KiB	391.24 KiB
d0deebd	21.58 KiB	542.28 KiB	520.69 KiB
c2acec5	22.85 KiB	408.88 KiB	386.03 KiB
8c50edb	20.76 KiB	432.31 KiB	411.55 KiB
ecd9ecd	20.76 KiB	420.23 KiB	399.47 KiB
7cd187e	20.76 KiB	401.65 KiB	380.89 KiB

Previous results on branch: armcknight/feat/launch-profile-data-in-app-start-spans

Startup times

Revision	Plain	With Sentry	Diff
82b16fe	1230.27 ms	1244.67 ms	14.40 ms
07e5edc	1244.73 ms	1253.24 ms	8.51 ms
c32b818	1237.06 ms	1251.63 ms	14.56 ms
9f00605	1233.63 ms	1246.52 ms	12.90 ms
389fb12	1228.85 ms	1249.57 ms	20.72 ms
0dd6fa2	1237.14 ms	1255.69 ms	18.55 ms
9d7d5a1	1207.23 ms	1230.02 ms	22.79 ms

App size

Revision	Plain	With Sentry	Diff
82b16fe	21.58 KiB	546.50 KiB	524.92 KiB
07e5edc	21.58 KiB	545.19 KiB	523.61 KiB
c32b818	21.58 KiB	546.60 KiB	525.02 KiB
9f00605	21.58 KiB	542.87 KiB	521.29 KiB
389fb12	21.58 KiB	542.88 KiB	521.29 KiB
0dd6fa2	21.58 KiB	546.57 KiB	524.99 KiB
9d7d5a1	21.58 KiB	546.58 KiB	525.00 KiB

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 89.437%. Comparing base (59c1b97) to head (b34fe84).

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3736       +/-   ##
=============================================
- Coverage   89.446%   89.437%   -0.010%     
=============================================
  Files          556       557        +1     
  Lines        60045     60240      +195     
  Branches     21560     21668      +108     
=============================================
+ Hits         53708     53877      +169     
- Misses        5303      5437      +134     
+ Partials      1034       926      -108     

Files	Coverage Δ
Sources/Sentry/SentryAppStartMeasurement.m	100.000% <100.000%> (ø)
Sources/Sentry/SentryAppStartTracker.m	97.633% <100.000%> (+0.014%)	⬆️
Sources/Sentry/SentryProfiler.mm	79.466% <100.000%> (+0.876%)	⬆️
Sources/Sentry/SentrySysctl.m	100.000% <100.000%> (ø)
Sources/Sentry/SentryTimeToDisplayTracker.m	100.000% <100.000%> (ø)
...SentryProfilerTests/SentryProfilerSwiftTests.swift	97.760% <100.000%> (+0.029%)	⬆️
...iewController/SentryTimeToDisplayTrackerTest.swift	99.436% <100.000%> (ø)
Tests/SentryTests/Protocol/TestData.swift	98.936% <100.000%> (ø)
...ts/SentryTests/Transaction/SentryTracerTests.swift	97.691% <100.000%> (+0.003%)	⬆️
Sources/Sentry/SentrySDK.m	90.579% <81.818%> (-0.398%)	⬇️
... and 2 more

... and 43 files with indirect coverage changes

---

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[brustolin]

Looking good.
Just a couple of comments.

[philipphofmann]

I found a few issues.

[philipphofmann]

Thanks for including most of the feedback 😃

[philipphofmann]

Thanks, @armcknight. LGTM