Sketch: Trigger R8's ServiceLoader optimization #12414
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load() unused since c8a94d1 in 2020.
| } | ||
| return candidates.get(0); | ||
| final PriorityAccessor<T> priorityAccessor) { | ||
| return loadAll(klass, ServiceLoader.load(klass, cl).iterator(), hardcoded, priorityAccessor); |
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If you're concerned about the performance of clients not using R8, I think you'll want to make the call to ServiceLoader.load() conditional on R8 being used. Otherwise the hardcoded fallback will never be used. I'm not aware of a way to do that aside from adding an -assumevalues rule.
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From my reading of ServiceLoader, load() doesn't do any reflection. All the reflection is done when iterating. So while we may create the ServiceLoader here, we'll throw the ServiceLoader's iterator away without using it on Android if it isn't derived from a List. That's a bit of a hack, but also seems reasonably likely to remain stable. But -assumevalues might be a good option too (assuming we can set it without upsetting non-R8 shrinking tools).
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Indeed! Does look that way on android at least.
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Just a sketch, but the neat thing is if we trigger the ServiceLoader optimization, that will keep the constructors for us, so we could use the hard-coded list or the fake-ServiceLoader-iterator and it should work fine either way.