tree: 2d41ab0691a0168f42c094112db69cbf4a4b2179 [path history] [tgz]
  4. deprecated_network_sync.fidl
  5. meta/
  6. service.config
  7. src/
  8. test/
  9. utc.fidl


netclock implements the fuchsia.time.Utc protocol.

Because netclock is implemented in Rust, we recommend that you have consulted the Fuchsia docs on developing with Rust.

Getting Started

Generate a Cargo.toml for your editor to use:

fx gen-cargo //src/sys/netclock:bin


fx rustdoc src/sys/netclock:bin --open


netclock itself is included in the core product configuration, no specific fx set is needed to ensure it is included in an image. You may wish to build only a small image like core‘s while working on this service. Our tests must be included explicitly in your device’s package universe:

fx set PRODUCT.ARCH --with //src/sys/netclock:tests

After this, fx build will include the test package as well.

Running tests

Once you have your build working:

fx shell killall netclock_bin_test.cmx ; fx run-test netclock_bin_test

This command ensures that any previous instances of the test have been exited before running again. Because deadlocks (and the need to exit them with ctrl+c) are common when writing event notification tests, dead test instances can stack up quickly during a development session.


Minimum before submitting a CL: fx rustfmt //src/sys/netclock:bin. Prefer fx format-code.


Minimum UTC (“backstop” time)

Devices store a minimum UTC value at /config/build-info/minimum-utc-stamp, which is generated at build time and included in the system image. It is stored as a Unix epoch (seconds since 1970, excluding leap seconds) and can be quickly observed on your current device. An example from the time of writing:

$ [fx shell --] cat /config/build-info/minimum-utc-stamp | date
Wed 17 Jul 2019 03:56:35 PM PDT

All reads of the UTC clock on a device must return a value at or after the time stored in the file.