platform2: migrate base or absl optional to std::optional

libchrome base::Optional is replaced by absl::optional on chromium
upstream and removed in r885735.
Since Chrome OS uses c++17, it can also use std::optional (as opposed to
Chrome which uses c++14). See go/use-std-optional-in-cros for
discussion.

Note, libchrome uses absl::optional because that is what upstream
chromium uses. However, in CrOS, absl switched to always use
std::optional implementation in crrev.com/c/2967691 so they are
equivalent.

LSC proposal: go/chromeos-lsc-optional-migration

BUG=b:192529039
TEST=CQ

Change-Id: Ie7b2497260e32766cabd4ba398cc7d94263d7ab0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/3325832
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Owners-Override: Dominick Ng <dominickn@google.com>
Commit-Queue: Grace Cham <hscham@chromium.org>
Tested-by: Grace Cham <hscham@chromium.org>
NOKEYCHECK=True
GitOrigin-RevId: a3c61bdb78ad8c2cc6f7790e26971c1844da6e78
16 files changed
tree: e0d7d0d55b2819de06a9125d69c6e95c79656057
  1. BUILD.gn
  2. common_types.cc
  3. common_types.h
  4. export.h
  5. iio_channel.h
  6. iio_channel_impl.cc
  7. iio_channel_impl.h
  8. iio_context.h
  9. iio_context_impl.cc
  10. iio_context_impl.h
  11. iio_device.cc
  12. iio_device.h
  13. iio_device_impl.cc
  14. iio_device_impl.h
  15. iio_device_test.cc
  16. iio_device_trigger_impl.cc
  17. iio_device_trigger_impl.h
  18. iio_event.cc
  19. iio_event.h
  20. iio_event_impl.cc
  21. iio_event_impl.h
  22. iio_event_test.cc
  23. libmems.pc
  24. libmems_test_support.pc
  25. OWNERS
  26. README.md
  27. test_fakes.cc
  28. test_fakes.h
README.md

Chrome OS IIO Sensor Utility Library

Project goal and motivation

This library provides a set of wrapper and test helpers around libiio.

It is meant to provide a common foundation for Chrome OS to access and interface IIO sensors, with:

  • a strong emphasis on testability;
  • readable code, with the ergonomics typical of platform2;
  • high performance.

Class hierarchy

At the root of the hierarchy, there exists the IioContext, which represents the IIO devices currently available on the system. These can be retrieved by name and inspected, via instances of IioDevice.

An IioDevice allows reading and writing attributes of an IIO device via type-safe helper APIs. It also offers support for configuring the buffer and trigger of an IIO device, which we use in order to allow the Chrome UI to read accelerometer data and support screen rotation.

An IioDevice also exposes a list of IioChannels, which can individually be enabled and disabled.

Test mocks

Useful mocks for the core classes are provided, such that a test author can focus on the logic of the unit tests and share a common testing language with other engineers working in this space. Sharing the foundation of testing IIO sensor access helps ensure that any improvement in this area can benefit all clients.