Aggregate metrics for spans

[markushi]

📜 Description

Aggregate metrics based on spans: https://develop.sentry.dev/sdk/metrics/#span-aggregation.

#skip-changelog
-- as the feature hasn't been released yet.

💡 Motivation and Context

Example event: https://sentry-sdks.sentry.io/performance/sentry-android%3A70c95de097d64ca68ebdbbe6f923d625/?openPanel=open&referrer=metrics#span-a39379e81c714978

In order to improve the link between metrics and spans (see RFC) we want to aggregate metric emissions when a span is active.

The span summary is grouped by export_key (an unique identifier, ignoring the metric tags) and then by metric_key (an unique identifier, including metric tags), the RFC provides a good example to illustrate why this is practical.

💚 How did you test it?

Added unit tests, as well as an integration test

📝 Checklist

• 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

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 36b152e

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	389.98 ms	447.06 ms	57.08 ms
Size	1.70 MiB	2.28 MiB	592.02 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
b7fa26f	440.10 ms	533.98 ms	93.88 ms
6b4dd70	399.62 ms	479.08 ms	79.47 ms
3d8bd2b	379.45 ms	450.36 ms	70.90 ms
4e29063	376.38 ms	390.98 ms	14.60 ms
86f0096	368.63 ms	446.92 ms	78.29 ms
0bd723b	412.52 ms	496.65 ms	84.13 ms
d6d2b2e	463.14 ms	545.56 ms	82.42 ms
4e29063	384.14 ms	447.74 ms	63.60 ms
4e260b3	378.73 ms	454.18 ms	75.45 ms
c7e2fbc	398.35 ms	468.52 ms	70.17 ms

App size

Revision	Plain	With Sentry	Diff
b7fa26f	1.70 MiB	2.27 MiB	583.82 KiB
6b4dd70	1.70 MiB	2.27 MiB	583.82 KiB
3d8bd2b	1.72 MiB	2.29 MiB	577.53 KiB
4e29063	1.72 MiB	2.29 MiB	578.38 KiB
86f0096	1.72 MiB	2.29 MiB	576.50 KiB
0bd723b	1.72 MiB	2.29 MiB	578.09 KiB
d6d2b2e	1.72 MiB	2.27 MiB	555.05 KiB
4e29063	1.72 MiB	2.29 MiB	578.38 KiB
4e260b3	1.72 MiB	2.27 MiB	554.95 KiB
c7e2fbc	1.72 MiB	2.29 MiB	576.40 KiB

Previous results on branch: feat/metrics-span-aggregations

Startup times

Revision	Plain	With Sentry	Diff
350fd13	411.08 ms	511.49 ms	100.41 ms
450fa50	399.91 ms	474.27 ms	74.35 ms
a5701de	385.06 ms	457.86 ms	72.79 ms
f88769c	381.13 ms	464.45 ms	83.32 ms
bac9455	398.20 ms	538.94 ms	140.74 ms
7ebd815	376.46 ms	456.26 ms	79.80 ms
b26392f	356.48 ms	429.53 ms	73.05 ms

App size

Revision	Plain	With Sentry	Diff
350fd13	1.70 MiB	2.28 MiB	591.92 KiB
450fa50	1.70 MiB	2.28 MiB	591.92 KiB
a5701de	1.70 MiB	2.28 MiB	591.93 KiB
f88769c	1.70 MiB	2.28 MiB	591.91 KiB
bac9455	1.70 MiB	2.28 MiB	591.91 KiB
7ebd815	1.70 MiB	2.28 MiB	591.91 KiB
b26392f	1.70 MiB	2.28 MiB	591.97 KiB

[stefanosiano]

Can we extract this logic into a new method in JsonObjectReader like nextMapOfListOrNull?
So we can reuse it in other places, like SentryTransaction

[stefanosiano]

is it a mistake?

[markushi]

Nope this is intended, it just ensures the getter returns a reference to the same LocalMetricsAggregator.
Let me add a comment for this 👍

[stefanosiano]

I would extract this into a Fixture class, and the verifys into some private methods

[stefanosiano]

Just left few minor comments, but good!