Upgrade prost-types and support type conversion in both directions

[ashlineldridge]

Hi, I would like to use quanta however it's version constraint of prost-types prevents me from being able to convert from an Instant to prost_types::Timestamp due to the version constraint as my code is using version 0.13 of prost and prost-types which contains a number of fixes and improvements. Would you be open to updating? There is this very old PR to upgrade to 0.12 but I would like to bump to 0.13. I can raise a PR if you like.

[ashlineldridge]

Additionally, is there any reason only conversion from quanta::Instant to prost_types::Timestamp is supported and not also the reverse? My use case is that I'm using Prost to create a bidirectional gRPC streaming server and I want to be able to use standard gRPC timestamps on the wire but I want to use the quanta::Instance type in my domain code and so I need to convert in both directions.

Would you be open to supporting this? I have forked and implemented the conversion in this commit.

[tobz]

Would you be open to supporting this? I have forked and implemented the conversion in this commit.

quanta::Instant is meant to mirror std::time::Instant insofar as it's opaque and only relevant on the system where the instant is measured. In that vein, the continued support for serializing to prost_types::Timestamp is actually an oversight on my part. It should have been removed when we removed support for Instant::as_u64.

I would recommend switching to std::time::SystemTime if you need a way to hold, and transport, wall-clock time across the process boundary.