Remove archetype_component_access from QueryState #12474
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james7132
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JoJoJet
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I don't really expect them to show up in the microbenchmarks since they all hit the ArchetypeGeneration check, come up empty, and return immediately. Might improve it a little bit by reducing instruction cache pressure a bit by having less codegen though. |
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# Objective Other than the exposed functions for reading matched tables and archetypes, a `QueryState` does not actually need both internal Vecs for storing matched archetypes and tables. In practice, it will only use one of the two depending on if it uses dense or archetypal iteration. Same vein as #12474. The goal is to reduce the memory overhead of using queries, which Bevy itself, ecosystem plugins, and end users are already fairly liberally using. ## Solution Add `StorageId`, which is a union over `TableId` and `ArchetypeId`, and store only one of the two at runtime. Read the slice as if it was one ID depending on whether the query is dense or not. This follows in the same vein as #5085; however, this one directly impacts heap memory usage at runtime, while #5085 primarily targeted transient pointers that might not actually exist at runtime. --- ## Changelog Changed: `QueryState::matched_tables` now returns an iterator instead of a reference to a slice. Changed: `QueryState::matched_archetypes` now returns an iterator instead of a reference to a slice. ## Migration Guide `QueryState::matched_tables` and `QueryState::matched_archetypes` does not return a reference to a slice, but an iterator instead. You may need to use iterator combinators or collect them into a Vec to use it as a slice. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
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Objective
QueryState::archetype_component_accessis only really ever used to extendSystemMeta's. It can be removed to save some memory for everyQueryin an app.Solution
new_archetypepass in a&mut Access<ArchetypeComponentId>instead and pull it fromSystemMetadirectly.QueryState::newfromQueryState::new_with_accessand a commonQueryState::new_uninitialized.new_archetypeinto an internal and public version. Call the internal version inupdate_archetypes.This should make it faster to construct new QueryStates, and by proxy lenses and joins as well.
matched_tablesalso similarly is only used to deduplicate inserting intomatched_table_ids. If we can find another efficient way to do so, it might also be worth removing.The generated assembly reflects this well, with all of the access related updates in
QueryStatebeing removed.Changelog
Removed:
QueryState::archetype_component_access.Changed:
QueryState::new_archetypenow takes a&mut Access<ArchetypeComponentId>argument, which will be updated with the new accesses.Changed:
QueryState::update_archetype_component_accessnow takes a&mut Access<ArchetypeComponentId>argument, which will be updated with the new accesses.Migration Guide
QueryState::archetype_component_accesshas been removed. This can be worked around by accessing the surroundingSystemState's instead. If you needed this explicitly forQueryState, please file an issue.