Metrics: use number for timestamp instead of interface

[mayurkale22]

No description provided.

[bogdandrutu]

And what is the unit?

[mayurkale22]

Are you asking about unit tests or unit type in MetricDescriptor?

[bogdandrutu]

Timestamp as a number should have a unit "us" or "ns" from the epoch. I am a bit lost in this PR logic.

[mayurkale22]

I was thinking to use Date.now() (to represent a time at which the value/gauge is recorded - format: milliseconds since epoch) for TimeSeries, Point and Exemplar timestamp attribute.
Looks like we did same thing here: https://github.com/census-instrumentation/opencensus-node/blob/master/packages/opencensus-core/src/stats/types.ts#L136

[bogdandrutu]

https://www.geeksforgeeks.org/javascript-date-now/ so it seems that the timestamp you are proposing is millis since epoch. Do we have a way to get better timestamps (ns or us granularity)?

[isaikevych]

https://www.geeksforgeeks.org/javascript-date-now/ so it seems that the timestamp you are proposing is millis since epoch. Do we have a way to get better timestamps (ns or us granularity)?

@mayurkale22 I dont know what are you going to achieve by this changes but anyway
@bogdandrutu nodejs has process.hrtime() which returns high-resolution real time in [seconds, nanoseconds] array then we had plans to use it and that is why protobuf generated Timestamp interface with seconds and nanos

[mayurkale22]

As discussed, will use process.hrtime() to get timstamp in ns or us granularity. Closing this PR.