Summary:
Collecting Telemetry is a crucial part of building a performant UI framework; we do that but we need to improve it to make the data more reliable, actionable and trustful.
Now we collect time points as the number of milliseconds from the start of the CLOCK_MONOTONIC epoch. That's fine but it also has problems:
Sometimes a millisecond is an eternity. We have only 16 (or fewer) of them on each frame. What if some operation takes 1ms (according to telemetry) but we have to run it a dozen times? Does it mean that it's 12 ms in total? So, we lack precision.
This is not type-safe. Do you know how many milliseconds in a microsecond? I don't. We multiply that on magical constants hoping that we copied that from some other place right.
The current implementation is not cross-platform. We have ifdefs for iOS and Android and Unix and Windows (which is now implemented).
So, this diff replaces that with using `std::chrono` which is part of the standard library that designed to fix all those concerns. We also define our type-aliases on top of that to express our concrete constrains:
We use `std::chrono::steady_clock` as the base clock which is according to the standard using `clock_gettime(CLOCK_MONOTONIC, ... )` if available. So, it's fast and compatible (the same under the hood) with Android infra.
We use nanoseconds when we store time durations (TelemetryDuration type).
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: JoshuaGross, mdvacca
Differential Revision: D19184569
fbshipit-source-id: 7a44688f4bb3bfc6e3009874f0075c531c8569a1
Valentin Shergin