tree: a340cc4b14127fd1c556a7b3f821f7142440ea81 [path history] [tgz]
  1. src/


injectable-time is a library to support dependency-injecting a time source.

It provides a trait TimeSource with one function, now(). The library uses i64 instead of an os-dependent time type so it can run host-side and in Fuchsia.

It provides three structs, UtcTime, MonotonicTime, and FakeTime, which implement TimeSource. FakeTime has functions set_ticks and add_ticks which can be used in tests.

The now() function of FakeTime returns the last number that was set_ticks by set_ticks(). It does not increment on multiple calls to now().

The now() function of UtcTime returns the number of nanoseconds since the Unix epoch.

The now() function of MonotonicTime returns a number of nanoseconds which monotonically increases at approximately a 1:1 rate with the wall clock.

Any struct that needs an injectable time source can store a &'a dyn TimeSource. Note the lack of mut.

A struct can also simply store a T: TimeSource. FakeTime can be clone()'d.

See the unit tests in for a usage example.


This project should be automatically included in builds.


injectable-time can be used by depending on the //src/lib/injectable-time gn target and then using the injectable-time crate in a Rust project.

injectable-time is not available in the sdk and is intended to be used only by diagnostics binaries.


Unit tests for injectable-time are available in the injectable-time package:

$ fx test injectable_time_lib_test

You'll need to include //src/lib/injectable-time:tests in your build, either by using fx args to put it under universe_package_labels, or by fx set_ticks [....] --with //src/lib/injectable-time:tests.