fix: Return SentryNoOpSpan when starting a child on a finished transaction

[kevinrenskers]

📜 Description

Return a SentryNoOpSpan when starting a child on a finished transaction, and log a warning.

💡 Motivation and Context

Closes #1624.

💚 How did you test it?

Unit test.

📝 Checklist

• I reviewed the submitted code
• I added tests to verify the changes
• I updated the docs if needed
• Review from the native team if needed
• No breaking changes

🔮 Next steps

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1243.76 ms	1262.20 ms	18.44 ms
Size	20.51 KiB	333.10 KiB	312.60 KiB

Baseline results on branch: master

Startup times

Revision	Plain	With Sentry	Diff
0fdf0b2	1243.92 ms	1250.86 ms	6.94 ms
b172a8b	1257.68 ms	1272.38 ms	14.70 ms
075911d	1256.73 ms	1271.22 ms	14.49 ms
0fdf0b2	1266.27 ms	1277.90 ms	11.63 ms
a5ca27b	1231.31 ms	1252.56 ms	21.25 ms
864c39a	1239.45 ms	1256.76 ms	17.31 ms
6177f2d	1206.55 ms	1226.20 ms	19.65 ms
4a66f00	1259.84 ms	1281.66 ms	21.82 ms
4c1fab4	1222.96 ms	1251.00 ms	28.04 ms
864c39a	1191.14 ms	1233.38 ms	42.24 ms

App size

Revision	Plain	With Sentry	Diff
0fdf0b2	20.51 KiB	332.90 KiB	312.39 KiB
b172a8b	20.51 KiB	331.79 KiB	311.28 KiB
075911d	20.51 KiB	332.90 KiB	312.39 KiB
0fdf0b2	20.51 KiB	332.90 KiB	312.39 KiB
a5ca27b	20.51 KiB	331.81 KiB	311.31 KiB
864c39a	20.51 KiB	335.57 KiB	315.06 KiB
6177f2d	20.51 KiB	332.90 KiB	312.40 KiB
4a66f00	20.51 KiB	331.79 KiB	311.28 KiB
4c1fab4	20.51 KiB	331.79 KiB	311.28 KiB
864c39a	20.51 KiB	335.57 KiB	315.06 KiB

Previous results on branch: fix/1624-finished-span-start-child

Startup times

Revision	Plain	With Sentry	Diff
320c2dd	1227.33 ms	1246.36 ms	19.03 ms
766f1f3	1231.44 ms	1247.42 ms	15.98 ms
7202f4f	1268.58 ms	1286.20 ms	17.62 ms
23978c6	1232.63 ms	1254.46 ms	21.83 ms
8468b08	1260.12 ms	1272.47 ms	12.35 ms
e9ec817	1235.72 ms	1258.86 ms	23.14 ms
137e8fe	1235.31 ms	1253.34 ms	18.03 ms

App size

Revision	Plain	With Sentry	Diff
320c2dd	20.51 KiB	333.10 KiB	312.60 KiB
766f1f3	20.51 KiB	333.10 KiB	312.60 KiB
7202f4f	20.51 KiB	332.69 KiB	312.18 KiB
23978c6	20.51 KiB	333.03 KiB	312.53 KiB
8468b08	20.51 KiB	333.04 KiB	312.53 KiB
e9ec817	20.51 KiB	333.11 KiB	312.60 KiB
137e8fe	20.51 KiB	333.11 KiB	312.60 KiB

[kevinrenskers]

As the child is now a NoOp span, there is no tracer (and you get an unrecognized selector failure).

[philipphofmann]

The Span should only return a NoOp if the transaction is finished, not itself.

[brustolin]

The Span should only return a NoOp if the transaction is finished, not itself.

If this is the requirement, we only need to check this at SentryTracer, since is the only place we actually create the child.

[brustolin]

LGTM