How to meet criteria of log structured timestamp?

[DasIch]

Background

Timestamps in the spec default to the current walltime, which is not monotonic. As a consequence it cannot be guaranteed that start timestamp <= finish timestamp holds.

Problem

The specification currently says about the optional timestamp parameter for log structured data:

An explicit timestamp. If specified, it must fall between the local start and finish time for the span.

https://github.com/opentracing/specification/blob/7d12968e7ffdbbd4032fc1d5346004e840e244ca/specification.md#log-structured-data

Emphasis mine.

This constraint is rather difficult to guarantee. For one, the finish time isn't known when this method is called. Additionally there is the problem of walltime not being monotonic. This means the timezone (+ DST info) needs to be taken into consideration to verify this.

In practice it seems that implementation simply ignore this constraint.

Proposal

I would suggest to bring the spec into alignment with existing implementations. The least invasive way to do so I can see would be to replace the "must" with "should", so that we arrive at:

An explicit timestamp. If specified, it should fall between the local start and finish time for the span.

Questions to address

n/a

[yurishkuro]

sgtm