Sentry SDK timestamp from NativeLaunch-to-Android-to-Flutter for User Perceived App Start

[thinkocapo]

Problem Statement

Customer wants to track the user perceived app start.

They don't custom instrument a span because the app start begins in the native layer, then goes to the android layer, then finally the flutter layer.

This feature request might also be needed in

• getsentry/sentry-native
• getsentry/sentry-java
  as it involves all 3 sdk layers

Solution Brainstorm

1. Sentry Native SDK records a startTimestamp as soon as Sentry Native SDK is initialized, as app is starting.
2. Sentry Native SDK propagates this startTimestamp to the Sentry Android SDK and Sentry Flutter SDK's
3. Customer can decide the exact moment in their Flutter code that the user's perceived app start has completed, and customer is willing to generate a currentTimestamp and subtract the startTimestamp to figure the total time elapsed
4. Customer to set this time elapsed as a Span Metric for tracking.

Customer could look into generating a startTimestamp themself in the native layer, and maybe track it via environmental variables and some kind of inter-layer communication, but was wondering if Sentry could assist in this.

Have other customers run into this sort of problem before?

Are you willing to submit a PR?

None

[kahest]

Hey @thinkocapo thanks for reporting - ignoring the proposed solution here for a minute, the actual use case

Customer wants to track the user perceived app start.

is exactly what the App Start integration is supposed to do. Please let us know if we're missing something.

[buenaflor]

@kahest I already replied in slack as well, they are essentially describing TTFD