a530c07bc5
Fixes #17720 ## Objective Spawning RelationshipTargets from scenes currently fails to preserve RelationshipTarget ordering (ex: `Children` has an arbitrary order). This is because it uses the normal hook flow to set up the collection, which means we are pushing onto the collection in _spawn order_ (which is currently in archetype order, which will often produce mismatched orderings). We need to preserve the ordering in the original RelationshipTarget collection. Ideally without expensive checking / fixups. ## Solution One solution would be to spawn in hierarchy-order. However this gets complicated as there can be multiple hierarchies, and it also means we can't spawn in more cache-friendly orders (ex: the current per-archetype spawning, or future even-smarter per-table spawning). Additionally, same-world cloning has _slightly_ more nuanced needs (ex: recursively clone linked relationships, while maintaining _original_ relationships outside of the tree via normal hooks). The preferred approach is to directly spawn the remapped RelationshipTarget collection, as this trivially preserves the ordering. Unfortunately we can't _just_ do that, as when we spawn the children with their Relationships (ex: `ChildOf`), that will insert a duplicate. We could "fixup" the collection retroactively by just removing the back half of duplicates, but this requires another pass / more lookups / allocating twice as much space. Additionally, it becomes complicated because observers could insert additional children, making it harder (aka more expensive) to determine which children are dupes and which are not. The path I chose is to support "opting out" of the relationship target hook in the contexts that need that, as this allows us to just cheaply clone the mapped collection. The relationship hook can look for this configuration when it runs and skip its logic when that happens. A "simple" / small-amount-of-code way to do this would be to add a "skip relationship spawn" flag to World. Sadly, any hook / observer that runs _as the result of an insert_ would also read this flag. We really need a way to scope this setting to a _specific_ insert. Therefore I opted to add a new `RelationshipInsertHookMode` enum and an `entity.insert_with_relationship_insert_hook_mode` variant. Obviously this is verbose and ugly. And nobody wants _more_ insert variants. But sadly this was the best I could come up with from a performance and capability perspective. If you have alternatives let me know! There are three variants: 1. `RelationshipInsertHookMode::Run`: always run relationship insert hooks (this is the default) 2. `RelationshipInsertHookMode::Skip`: do not run any relationship insert hooks for this insert (this is used by spawner code) 3. `RelationshipInsertHookMode::RunIfNotLinked`: only run hooks for _unlinked_ relationships (this is used in same-world recursive entity cloning to preserve relationships outside of the deep-cloned tree) Note that I have intentionally only added "insert with relationship hook mode" variants to the cases we absolutely need (everything else uses the default `Run` mode), just to keep the code size in check. I do not think we should add more without real _very necessary_ use cases. I also made some other minor tweaks: 1. I split out `SourceComponent` from `ComponentCloneCtx`. Reading the source component no longer needlessly blocks mutable access to `ComponentCloneCtx`. 2. Thanks to (1), I've removed the `RefCell` wrapper over the cloned component queue. 3. (1) also allowed me to write to the EntityMapper while queuing up clones, meaning we can reserve entities during the component clone and write them to the mapper _before_ inserting the component, meaning cloned collections can be mapped on insert. 4. I've removed the closure from `write_target_component_ptr` to simplify the API / make it compatible with the split `SourceComponent` approach. 5. I've renamed `EntityCloner::recursive` to `EntityCloner::linked_cloning` to connect that feature more directly with `RelationshipTarget::LINKED_SPAWN` 6. I've removed `EntityCloneBehavior::RelationshipTarget`. This was always intended to be temporary, and this new behavior removes the need for it. --------- Co-authored-by: Viktor Gustavsson <villor94@gmail.com> |
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| README.md | ||
Bevy Benchmarks
This is a crate with a collection of benchmarks for Bevy.
Running benchmarks
Benchmarks can be run through Cargo:
# Run all benchmarks. (This will take a while!)
cargo bench -p benches
# Just compile the benchmarks, do not run them.
cargo bench -p benches --no-run
# Run the benchmarks for a specific crate. (See `Cargo.toml` for a complete list of crates
# tracked.)
cargo bench -p benches --bench ecs
# Filter which benchmarks are run based on the name. This will only run benchmarks whose name
# contains "name_fragment".
cargo bench -p benches -- name_fragment
# List all available benchmarks.
cargo bench -p benches -- --list
# Save a baseline to be compared against later.
cargo bench -p benches --save-baseline before
# Compare the current benchmarks against a baseline to find performance gains and regressions.
cargo bench -p benches --baseline before
Criterion
Bevy's benchmarks use Criterion. If you want to learn more about using Criterion for comparing performance against a baseline or generating detailed reports, you can read the Criterion.rs documentation.