Fix Worker usage on PS4 browser #1401
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peaBerberian
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After #1401 (fix about the fact that `typeof Worker === "object"` on the PlayStation 4 for some reason), I finally succeeded to run the `MULTI_THREAD` experimental feature on a PlayStation 4 by adding one supplementary fix. Turns out that the `performance.now` web API, that we use to measure time differences (Date.now() being clock-related, it's not always appropriate for that) was not available in a Worker environment on the PlayStation 4. I have no idea why, as it is available in main thread, a random guess would be that this is a remnant of mitigations against something like spectre/meltdown but all I could find is that [they reduced its precision](https://trac.webkit.org/changeset/226495/webkit), not removed it from worker. Anyway, we thankfully only relied on this API at two places, as we voluntarily reduced those places previously to allow a synchronization mechanism between main thread and worker. This means that we can now easily use `Date.now()` in its place when `performance.now()` is unavailable without much fear of the issue coming back again in the future (our linter already ensure the API isn't used elsewhere). The main issue would be that timing measures would now become time-dependant on the PlayStation 4 and thus may be affected by clock changes, or subtle unix timestamp quirks. This should very rarely be problematic though, and it will just happen when the experimental `MULTI_THREAD` feature is explicitely relied on on the PlayStation 4 for now.
We noticed that ps4 applications were not relying on the `MULTI_THREAD` despite being theoretically compatible with it. Turns out that `typeof Worker` does not return `"function"` as expected with such objects but `"object"` instead on that browser. Thus, the RxPlayer believes that it hasn't access to the Worker API, the necessary requirement for the `MULTI_THREAD` feature. I suppose that this may also be true for other old Webkit-based browsers, though it isn't for recent-ish webkitgtk-based browsers on my PC, so for now I only enforce it for the PlayStation 4.
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Florent-Bouisset
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peaBerberian
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After #1401 (fix about the fact that `typeof Worker === "object"` on the PlayStation 4 for some reason), I finally succeeded to run the `MULTI_THREAD` experimental feature on a PlayStation 4 by adding one supplementary fix. Turns out that the `performance.now` web API, that we use to measure time differences (Date.now() being clock-related, it's not always appropriate for that) was not available in a Worker environment on the PlayStation 4. I have no idea why, as it is available in main thread, a random guess would be that this is a remnant of mitigations against something like spectre/meltdown but all I could find is that [they reduced its precision](https://trac.webkit.org/changeset/226495/webkit), not removed it from worker. Anyway, we thankfully only relied on this API at two places, as we voluntarily reduced those places previously to allow a synchronization mechanism between main thread and worker. This means that we can now easily use `Date.now()` in its place when `performance.now()` is unavailable without much fear of the issue coming back again in the future (our linter already ensure the API isn't used elsewhere). The main issue would be that timing measures would now become time-dependant on the PlayStation 4 and thus may be affected by clock changes, or subtle unix timestamp quirks. This should very rarely be problematic though, and it will just happen when the experimental `MULTI_THREAD` feature is explicitely relied on on the PlayStation 4 for now.
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We noticed that ps4 applications were not relying on the
MULTI_THREADdespite being theoretically compatible with it.Turns out that
typeof Workerdoes not return"function"as expected with such objects but"object"instead on that browser. Thus, the RxPlayer believes that it hasn't access to the Worker API, the necessary requirement for theMULTI_THREADfeature.I suppose that this may also be true for other old Webkit-based browsers, though it isn't for recent-ish webkitgtk-based browsers on my PC, so for now I only enforce it for the PlayStation 4.