Add discrete events

[daniel-white]

Background

Sometimes it is advantageous to capture discrete events as a single point in time, not over a duration.

Problem

Currently the specification doesn't seem to have any way of reporting a single point in time event. A log doesn't quite make sense to display all of them on a flame graph.

Proposal

I propose that a discrete API be added. This would allow applications to report a point in time event. These could be added as flags on a flame chart similar to Visual Studio's Diagnostic tools (https://devblogs.microsoft.com/visualstudio/analyze-cpu-memory-while-debugging/)

Various implementations could add customization points as to what kind of flag should be shown.

Questions to address

• How will current implementations add this to avoid breaking changes?

[yurishkuro]

Point-in-time events can be captured via span.log() today, but they lack causality links between them.