RUM-7795 Anonymous RUM Identifier

[maciejburda]

What and why?

Adds capability of tracking anonymous id (enabled by default). This data allows linking sessions coming from the same device.

How?

Following proposal from this RFC (internal) it reuses data store mechanism, and based on configuration it generates and reuses stored identifier.

This identifier is attached to UserInfo object (schema already updated), which is enriching other SDK events.

NOTE: The identifier is read asynchronously from a file, which means RUM events created immediately after calling RUM.enable() will not include it. However, this is not an issue since the anonymous_id belongs to the Session entity. As long as the anonymous_id is present in at least in one event, it is sufficient for linking.

Here is corresponding PR for Android:
DataDog/dd-sdk-android#2487

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference
• Add CHANGELOG entry for user facing changes
• Add Objective-C interface for public APIs (see our guidelines [internal]) and run make api-surface)

[datadog-datadog-prod-us1]

Datadog Report

Branch report: maciey/RUM-7795/anonymous-id
Commit report: 777da2e
Test service: dd-sdk-ios

✅ 0 Failed, 1013 Passed, 2754 Skipped, 47.38s Total duration (1m 45.5s time saved)

[mariedm]

LGMT! Only a few minor comments.

[ncreated]

It looks great overall 👌 - I only left suggestions on naming and documenting the public API.

Requesting a change tho, to add integration unit tests for this feature. Using real instance of the SDK + proxy and asserting that anonymous ID is generated and inserted into events of two RUM sessions started in two instances of the SDK. I can help and pair on this 🙌

[simaoseica-dd]

Some small nits
👍

[maciejburda]

/merge

[dd-devflow]

Devflow running: /merge

View all feedbacks in Devflow UI.

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2025-02-10 10:42:25 UTC ℹ️ MergeQueue: waiting for PR to be ready

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2025-02-10 14:04:14 UTC ℹ️ MergeQueue: merge request added to the queue

The median merge time in develop is 27m.

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2025-02-10 14:45:06 UTC ℹ️ MergeQueue: This merge request was merged