data delivery: Set timestamp as an "unsafe shared current time"
#280
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Follow-up to #274, related to #257. The wording used in #274, which mentions platform-specific timestamps, made more sense in the context of the Generic Sensor API spec, as multiple platform-specific sensor APIs provide samples with timestamps in a platform-specific format that needs to be converted. Of the OS-provided telemetry APIs, however, only Windows optionally provides samples with a timestamp. As such, it makes more sense to define a timestamp using the monotonic clock's unsafe current time instead. Aditionally, the accompanying note was rewritten to indicate that the same value should be used for all globals, otherwise the same sample would end up with different "raw" timestamps in different frames/workers.
rakuco
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Jun 12, 2024
…ases With platform collectors now being per-global and per-source type, we need a way to clearly indicate that the "unprocessed" timestamp from a sample (i.e. what is fed to "relative high resolution time") must be the same across all globals. We also need to make sure that this works for both real and virtual pressure sources. - The abstract "pressure source" concept added a few commits ago now has an accompanying "pressure source sample" concept. It is a struct holding implementation-defined telemetry data as well as a timestamp corresponding to when it was obtained. Functionally, this should be identical to the what the spec has as of pull request w3c#280. - Virtual pressure source's "pending samples" is now a struct as well, holding similar data: a PressureState (like before) and a timestamp that is set to the "unshared current time" when the "update virtual pressure source" endpoint is called. - The "data collection" algorithm is responsible for reading either a "pressure source sample" or a virtual pressure source's "pending sample" and processing the timestamp value as necessary.
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LGTM. It makes sense! Thanks for fixing it. |
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Follow-up to #274, related to #257.
The wording used in #274, which mentions platform-specific timestamps, made more sense in the context of the Generic Sensor API spec, as multiple platform-specific sensor APIs provide samples with timestamps in a platform-specific format that needs to be converted.
Of the OS-provided telemetry APIs, however, only Windows optionally provides samples with a timestamp. As such, it makes more sense to define a timestamp using the monotonic clock's unsafe current time instead. Aditionally, the accompanying note was rewritten to indicate that the same value should be used for all globals, otherwise the same sample would end up with different "raw" timestamps in different frames/workers.
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