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Don't allocate for ComponentDescriptors of non-dynamic component types (#4725)

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# Objective
Don't allocate memory for Component types known at compile-time. Save a bit of memory.

## Solution
Change `ComponentDescriptor::name` from `String` to `Cow<'static, str>` to use the `&'static str` returned by `std::any::type_name`.
This commit is contained in:
James Liu 2022-05-30 21:16:47 +00:00
parent c174945208
commit d313ba59bd
1 changed files with 8 additions and 7 deletions
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15
crates/bevy_ecs/src/component.rs
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@ -10,6 +10,7 @@ use bevy_ptr::OwningPtr;
use std::{ use std::{
alloc::Layout, alloc::Layout,
any::{Any, TypeId}, any::{Any, TypeId},
borrow::Cow,
mem::needs_drop, mem::needs_drop,
}; };
@ -164,7 +165,7 @@ impl SparseSetIndex for ComponentId {
} }
pub struct ComponentDescriptor { pub struct ComponentDescriptor {
name: String, name: Cow<'static, str>,
// SAFETY: This must remain private. It must match the statically known StorageType of the // SAFETY: This must remain private. It must match the statically known StorageType of the
// associated rust component type if one exists. // associated rust component type if one exists.
storage_type: StorageType, storage_type: StorageType,
@ -201,7 +202,7 @@ impl ComponentDescriptor {
/// Create a new `ComponentDescriptor` for the type `T`. /// Create a new `ComponentDescriptor` for the type `T`.
pub fn new<T: Component>() -> Self { pub fn new<T: Component>() -> Self {
Self { Self {
name: std::any::type_name::<T>().to_string(), name: Cow::Borrowed(std::any::type_name::<T>()),
storage_type: T::Storage::STORAGE_TYPE, storage_type: T::Storage::STORAGE_TYPE,
is_send_and_sync: true, is_send_and_sync: true,
type_id: Some(TypeId::of::<T>()), type_id: Some(TypeId::of::<T>()),
@ -216,13 +217,13 @@ impl ComponentDescriptor {
/// - the `drop` fn must be usable on a pointer with a value of the layout `layout` /// - the `drop` fn must be usable on a pointer with a value of the layout `layout`
/// - the component type must be safe to access from any thread (Send + Sync in rust terms) /// - the component type must be safe to access from any thread (Send + Sync in rust terms)
pub unsafe fn new_with_layout( pub unsafe fn new_with_layout(
name: String, name: impl Into<Cow<'static, str>>,
storage_type: StorageType, storage_type: StorageType,
layout: Layout, layout: Layout,
drop: Option<for<'a> unsafe fn(OwningPtr<'a>)>, drop: Option<for<'a> unsafe fn(OwningPtr<'a>)>,
) -> Self { ) -> Self {
Self { Self {
name, name: name.into(),
storage_type, storage_type,
is_send_and_sync: true, is_send_and_sync: true,
type_id: None, type_id: None,
@ -236,7 +237,7 @@ impl ComponentDescriptor {
/// The [`StorageType`] for resources is always [`TableStorage`]. /// The [`StorageType`] for resources is always [`TableStorage`].
pub fn new_resource<T: Resource>() -> Self { pub fn new_resource<T: Resource>() -> Self {
Self { Self {
name: std::any::type_name::<T>().to_string(), name: Cow::Borrowed(std::any::type_name::<T>()),
// PERF: `SparseStorage` may actually be a more // PERF: `SparseStorage` may actually be a more
// reasonable choice as `storage_type` for resources. // reasonable choice as `storage_type` for resources.
storage_type: StorageType::Table, storage_type: StorageType::Table,
@ -249,7 +250,7 @@ impl ComponentDescriptor {
fn new_non_send<T: Any>(storage_type: StorageType) -> Self { fn new_non_send<T: Any>(storage_type: StorageType) -> Self {
Self { Self {
name: std::any::type_name::<T>().to_string(), name: Cow::Borrowed(std::any::type_name::<T>()),
storage_type, storage_type,
is_send_and_sync: false, is_send_and_sync: false,
type_id: Some(TypeId::of::<T>()), type_id: Some(TypeId::of::<T>()),
@ -270,7 +271,7 @@ impl ComponentDescriptor {
#[inline] #[inline]
pub fn name(&self) -> &str { pub fn name(&self) -> &str {
&self.name self.name.as_ref()
} }
} }