Switch usage of std HashMap/HashSet default hasher, to aHash algo (#258)

switch to ahash for HashMaps and HashSets via a new bevy_utils crate

Cargo.toml

@@ -57,6 +57,7 @@ bevy_sprite = { path = "crates/bevy_sprite", version = "0.1" }
 bevy_transform = { path = "crates/bevy_transform", version = "0.1" }
 bevy_text = { path = "crates/bevy_text", version = "0.1" }
 bevy_ui = { path = "crates/bevy_ui", version = "0.1" }
+bevy_utils = { path = "crates/bevy_utils", version = "0.1" }
 bevy_window = { path = "crates/bevy_window", version = "0.1" }
 
 # bevy (optional)

crates/bevy_asset/Cargo.toml

@@ -19,6 +19,7 @@ bevy_app = { path = "../bevy_app", version = "0.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_type_registry = { path = "../bevy_type_registry", version = "0.1" }
 bevy_property = { path = "../bevy_property", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 uuid = { version = "0.8", features = ["v4", "serde"] }

crates/bevy_asset/src/asset_server.rs

@@ -4,10 +4,10 @@ use crate::{
 };
 use anyhow::Result;
 use bevy_ecs::{Res, Resource, Resources};
+use bevy_utils::{HashMap, HashSet};
 use crossbeam_channel::TryRecvError;
 use parking_lot::RwLock;
 use std::{
-    collections::{HashMap, HashSet},
     env, fs, io,
     path::{Path, PathBuf},
     sync::Arc,
@@ -185,7 +185,7 @@ impl AssetServer {
     #[cfg(feature = "filesystem_watcher")]
     pub fn filesystem_watcher_system(asset_server: Res<AssetServer>) {
         use notify::event::{Event, EventKind, ModifyKind};
-        let mut changed = HashSet::new();
+        let mut changed = HashSet::default();
 
         while let Some(filesystem_watcher) = asset_server.filesystem_watcher.read().as_ref() {
             let result = match filesystem_watcher.receiver.try_recv() {

crates/bevy_asset/src/assets.rs

@@ -5,7 +5,7 @@ use crate::{
 use bevy_app::{prelude::Events, AppBuilder};
 use bevy_ecs::{FromResources, IntoQuerySystem, ResMut, Resource};
 use bevy_type_registry::RegisterType;
-use std::collections::HashMap;
+use bevy_utils::HashMap;
 
 /// Events that happen on assets of type `T`
 pub enum AssetEvent<T: Resource> {

crates/bevy_core/Cargo.toml

@@ -15,4 +15,5 @@ bevy_derive = { path = "../bevy_derive", version = "0.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_property = { path = "../bevy_property", version = "0.1" }
 bevy_type_registry = { path = "../bevy_type_registry", version = "0.1" }
-bevy_math = { path = "../bevy_math", version = "0.1" }
+bevy_math = { path = "../bevy_math", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }

crates/bevy_core/src/label.rs

@@ -1,8 +1,8 @@
 use bevy_ecs::prelude::*;
 use bevy_property::Properties;
+use bevy_utils::{HashMap, HashSet};
 use std::{
     borrow::Cow,
-    collections::{HashMap, HashSet},
     fmt::Debug,
     ops::{Deref, DerefMut},
 };
@@ -29,7 +29,7 @@ where
     T: IntoIterator<Item = L>,
 {
     fn from(value: T) -> Self {
-        let mut labels = HashSet::new();
+        let mut labels = HashSet::default();
         for label in value {
             labels.insert(label.into());
         }

crates/bevy_diagnostic/Cargo.toml

@@ -17,7 +17,8 @@ profiler = ["bevy_ecs/profiler"]
 bevy_app = { path = "../bevy_app", version = "0.1" }
 bevy_core = { path = "../bevy_core", version = "0.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 uuid = { version = "0.8", features = ["v4", "serde"] }
-parking_lot = "0.10"
+parking_lot = "0.10"

crates/bevy_diagnostic/src/diagnostic.rs

@@ -1,5 +1,6 @@
+use bevy_utils::HashMap;
 use std::{
-    collections::{HashMap, VecDeque},
+    collections::VecDeque,
     time::{Duration, SystemTime},
 };
 use uuid::Uuid;

crates/bevy_diagnostic/src/system_profiler.rs

@@ -1,7 +1,8 @@
 use crate::{Diagnostic, DiagnosticId, Diagnostics};
 use bevy_ecs::{Profiler, Res, ResMut};
+use bevy_utils::HashMap;
 use parking_lot::RwLock;
-use std::{borrow::Cow, collections::HashMap, sync::Arc, time::Instant};
+use std::{borrow::Cow, sync::Arc, time::Instant};
 
 #[derive(Debug)]
 struct SystemRunInfo {

crates/bevy_ecs/Cargo.toml

@@ -15,6 +15,7 @@ profiler = []
 
 [dependencies]
 bevy_hecs = { path = "hecs", features = ["macros", "serialize"], version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 rand = "0.7.2"
 rayon = "1.3"
 crossbeam-channel = "0.4.2"

crates/bevy_ecs/hecs/Cargo.toml

@@ -28,7 +28,7 @@ serialize = ["serde"]
 
 [dependencies]
 bevy_hecs_macros = { path = "macros", version = "0.1.3", optional = true }
-hashbrown = { version = "0.8.0", default-features = false, features = ["ahash", "inline-more"] }
+bevy_utils = { path = "../../bevy_utils", version = "0.1" }
 lazy_static = { version = "1.4.0", optional = true, features = ["spin_no_std"] }
 serde = { version = "1", features = ["derive"], optional = true}
 rand = "0.7.3"

crates/bevy_ecs/hecs/macros/src/lib.rs

@@ -83,7 +83,7 @@ pub fn derive_bundle(input: TokenStream) -> TokenStream {
 
                 #path::lazy_static::lazy_static! {
                     static ref ELEMENTS: [TypeId; #n] = {
-                        let mut dedup = std::collections::HashSet::new();
+                        let mut dedup = #path::bevy_utils::HashSet::default();
                         for &(ty, name) in [#((std::any::TypeId::of::<#tys>(), std::any::type_name::<#tys>())),*].iter() {
                             if !dedup.insert(ty) {
                                 panic!("{} has multiple {} fields; each type must occur at most once!", stringify!(#ident), name);

crates/bevy_ecs/hecs/src/archetype.rs

@@ -20,6 +20,7 @@ use crate::alloc::{
     vec,
     vec::Vec,
 };
+use bevy_utils::{HashMap, HashMapExt};
 use core::{
     any::{type_name, TypeId},
     cell::UnsafeCell,
@@ -27,8 +28,6 @@ use core::{
     ptr::{self, NonNull},
 };
 
-use hashbrown::HashMap;
-
 use crate::{borrow::AtomicBorrow, query::Fetch, Access, Component, Query};
 
 /// A collection of entities having the same component types

crates/bevy_ecs/hecs/src/entities.rs

@@ -1,7 +1,7 @@
 // modified by Bevy contributors
 
+use bevy_utils::HashMap;
 use core::fmt;
-use hashbrown::HashMap;
 #[cfg(feature = "std")]
 use std::error::Error;
 

crates/bevy_ecs/hecs/src/entity_builder.rs

@@ -20,14 +20,14 @@ use crate::alloc::{
     vec,
     vec::Vec,
 };
+
+use bevy_utils::HashSet;
 use core::{
     any::TypeId,
     mem::{self, MaybeUninit},
     ptr,
 };
 
-use hashbrown::HashSet;
-
 use crate::{archetype::TypeInfo, Component, DynamicBundle};
 
 /// Helper for incrementally constructing a bundle of components with dynamic component types
@@ -59,7 +59,7 @@ impl EntityBuilder {
             storage: Box::new([]),
             info: Vec::new(),
             ids: Vec::new(),
-            id_set: HashSet::new(),
+            id_set: HashSet::default(),
         }
     }
 

crates/bevy_ecs/hecs/src/lib.rs

@@ -89,6 +89,8 @@ pub use world::{ArchetypesGeneration, Component, ComponentError, Iter, SpawnBatc
 // Unstable implementation details needed by the macros
 #[doc(hidden)]
 pub use archetype::TypeInfo;
+#[doc(hidden)]
+pub use bevy_utils;
 #[cfg(feature = "macros")]
 #[doc(hidden)]
 pub use lazy_static;

crates/bevy_ecs/hecs/src/world.rs

@@ -15,13 +15,12 @@
 // modified by Bevy contributors
 
 use crate::alloc::vec::Vec;
+use bevy_utils::{HashMap, HashSet};
 use core::{any::TypeId, convert::TryFrom, fmt, mem, ptr};
 
 #[cfg(feature = "std")]
 use std::error::Error;
 
-use hashbrown::{HashMap, HashSet};
-
 use crate::{
     archetype::Archetype,
     entities::{Entities, Location},
@@ -363,7 +362,7 @@ impl World {
         entity: Entity,
         components: impl DynamicBundle,
     ) -> Result<(), NoSuchEntity> {
-        use hashbrown::hash_map::Entry;
+        use std::collections::hash_map::Entry;
 
         let loc = self.entities.get_mut(entity)?;
         unsafe {
@@ -461,7 +460,7 @@ impl World {
     /// assert_eq!(*world.get::<bool>(e).unwrap(), true);
     /// ```
     pub fn remove<T: Bundle>(&mut self, entity: Entity) -> Result<T, ComponentError> {
-        use hashbrown::hash_map::Entry;
+        use std::collections::hash_map::Entry;
 
         let loc = self.entities.get_mut(entity)?;
         unsafe {

crates/bevy_ecs/src/resource/resources.rs

@@ -1,8 +1,9 @@
 use super::{FetchResource, ResourceQuery};
 use crate::system::SystemId;
 use bevy_hecs::{Archetype, Ref, RefMut, TypeInfo};
+use bevy_utils::HashMap;
 use core::any::TypeId;
-use std::{collections::HashMap, ptr::NonNull};
+use std::ptr::NonNull;
 
 /// A Resource type
 pub trait Resource: Send + Sync + 'static {}
@@ -64,7 +65,7 @@ impl Resources {
             ResourceData {
                 archetype: Archetype::new(types),
                 default_index: None,
-                system_id_to_archetype_index: HashMap::new(),
+                system_id_to_archetype_index: HashMap::default(),
             }
         });
 

crates/bevy_ecs/src/schedule/schedule.rs

@@ -4,12 +4,9 @@ use crate::{
     system::{System, SystemId, ThreadLocalExecution},
 };
 use bevy_hecs::World;
+use bevy_utils::{HashMap, HashSet};
 use parking_lot::Mutex;
-use std::{
+use std::{borrow::Cow, sync::Arc};
-    borrow::Cow,
-    collections::{HashMap, HashSet},
-    sync::Arc,
-};
 
 /// An ordered collection of stages, which each contain an ordered list of [System]s.
 /// Schedules are essentially the "execution plan" for an App's systems.

crates/bevy_ecs/src/system/system.rs

@@ -1,7 +1,8 @@
 use crate::resource::Resources;
 use bevy_hecs::{Access, Query, World};
+use bevy_utils::HashSet;
 use fixedbitset::FixedBitSet;
-use std::{any::TypeId, borrow::Cow, collections::HashSet};
+use std::{any::TypeId, borrow::Cow};
 
 /// Determines the strategy used to run the `run_thread_local` function in a [System]
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]

crates/bevy_input/Cargo.toml

@@ -14,7 +14,11 @@ default = []
 serialize = ["serde"]
 
 [dependencies]
+# bevy
 bevy_app = { path = "../bevy_app", version = "0.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_math = { path = "../bevy_math", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
+
+# other
 serde = { version = "1", features = ["derive"], optional = true }

crates/bevy_input/src/input.rs

@@ -1,4 +1,5 @@
-use std::{collections::HashSet, hash::Hash};
+use bevy_utils::HashSet;
+use std::hash::Hash;
 
 /// A "press-able" input of type `T`
 pub struct Input<T> {

crates/bevy_property/Cargo.toml

@@ -14,9 +14,10 @@ keywords = ["bevy"]
 bevy_ecs = {path = "../bevy_ecs", version = "0.1"}
 bevy_math = {path = "../bevy_math", version = "0.1"}
 bevy_property_derive = {path = "bevy_property_derive", version = "0.1"}
+bevy_utils = {path = "../bevy_utils", version = "0.1"}
 
 # other
 erased-serde = "0.3"
 bevy_ron = {path = "../bevy_ron", version = "0.1.3"}
 serde = "1"
-smallvec = {version = "1.4", features = ["serde"]}
+smallvec = {version = "1.4", features = ["serde"]}

crates/bevy_property/src/dynamic_properties.rs

@@ -2,8 +2,9 @@ use crate::{
     property_serde::{DynamicPropertiesDeserializer, DynamicPropertiesSerializer, Serializable},
     DeserializeProperty, Properties, Property, PropertyIter, PropertyType, PropertyTypeRegistry,
 };
+use bevy_utils::HashMap;
 use serde::de::DeserializeSeed;
-use std::{any::Any, borrow::Cow, collections::HashMap};
+use std::{any::Any, borrow::Cow};
 
 pub struct DynamicProperties {
     pub type_name: String,

crates/bevy_property/src/impl_property/impl_property_std.rs

@@ -7,7 +7,7 @@ use serde::{Deserialize, Serialize};
 use std::{
     any::Any,
     collections::{BTreeMap, HashMap, HashSet},
-    hash::Hash,
+    hash::{BuildHasher, Hash},
     ops::Range,
 };
 
@@ -105,10 +105,11 @@ where
 
 // impl_property!(SEQUENCE, VecDeque<T> where T: Clone + Send + Sync + Serialize + 'static);
 impl_property!(Option<T> where T: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de> + 'static);
-impl_property!(HashSet<T> where T: Clone + Eq + Send + Sync + Hash + Serialize + for<'de> Deserialize<'de> + 'static);
+impl_property!(HashSet<T, H> where T: Clone + Eq + Send + Sync + Hash + Serialize + for<'de> Deserialize<'de> + 'static, H: Clone + Send + Sync + Default + BuildHasher + 'static);
-impl_property!(HashMap<K, V> where
+impl_property!(HashMap<K, V, H> where
     K: Clone + Eq + Send + Sync + Hash + Serialize + for<'de> Deserialize<'de> + 'static,
-    V: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de> + 'static,);
+    V: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de> + 'static,
+    H: Clone + Send + Sync + Default + BuildHasher + 'static);
 impl_property!(BTreeMap<K, V> where
     K: Clone + Ord + Send + Sync + Serialize + for<'de> Deserialize<'de> + 'static,
     V: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de> + 'static);

crates/bevy_property/src/type_registry.rs

@@ -1,8 +1,6 @@
 use crate::{DeserializeProperty, Property};
-use std::{
+use bevy_utils::{HashMap, HashSet};
-    any::TypeId,
+use std::any::TypeId;
-    collections::{HashMap, HashSet},
-};
 
 #[derive(Default)]
 pub struct PropertyTypeRegistry {

crates/bevy_render/Cargo.toml

@@ -21,6 +21,7 @@ bevy_property = { path = "../bevy_property", version = "0.1" }
 bevy_transform = { path = "../bevy_transform", version = "0.1" }
 bevy_type_registry = { path = "../bevy_type_registry", version = "0.1" }
 bevy_window = { path = "../bevy_window", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # rendering
 spirv-reflect = "0.2.3"

crates/bevy_render/src/batch/batcher.rs

@@ -1,6 +1,7 @@
 use super::Batch;
+use bevy_utils::HashMap;
 use smallvec::{smallvec, SmallVec};
-use std::{borrow::Cow, collections::HashMap, hash::Hash};
+use std::{borrow::Cow, hash::Hash};
 
 // TODO: add sorting by primary / secondary handle to reduce rebinds of data
 

crates/bevy_render/src/camera/active_cameras.rs

@@ -1,6 +1,6 @@
 use super::Camera;
 use bevy_ecs::{Entity, Query, ResMut};
-use std::collections::HashMap;
+use bevy_utils::HashMap;
 
 #[derive(Default)]
 pub struct ActiveCameras {

crates/bevy_render/src/mesh/mesh.rs

@@ -11,7 +11,8 @@ use bevy_asset::{AssetEvent, Assets, Handle};
 use bevy_core::AsBytes;
 use bevy_ecs::{Local, Query, Res, ResMut};
 use bevy_math::*;
-use std::{borrow::Cow, collections::HashSet};
+use bevy_utils::HashSet;
+use std::borrow::Cow;
 use thiserror::Error;
 
 pub const VERTEX_BUFFER_ASSET_INDEX: usize = 0;
@@ -506,7 +507,7 @@ pub fn mesh_resource_provider_system(
             vertex_buffer_descriptor
         }
     };
-    let mut changed_meshes = HashSet::new();
+    let mut changed_meshes = HashSet::<Handle<Mesh>>::default();
     let render_resource_context = &**render_resource_context;
     for event in state.mesh_event_reader.iter(&mesh_events) {
         match event {

crates/bevy_render/src/pipeline/bind_group.rs

@@ -1,8 +1,6 @@
 use super::BindingDescriptor;
-use std::{
+use bevy_utils::AHasher;
-    collections::hash_map::DefaultHasher,
+use std::hash::{Hash, Hasher};
-    hash::{Hash, Hasher},
-};
 
 #[derive(Clone, Debug, Eq)]
 pub struct BindGroupDescriptor {
@@ -27,7 +25,7 @@ impl BindGroupDescriptor {
     }
 
     pub fn update_id(&mut self) {
-        let mut hasher = DefaultHasher::new();
+        let mut hasher = AHasher::default();
         self.hash(&mut hasher);
         self.id = BindGroupDescriptorId(hasher.finish());
     }

crates/bevy_render/src/pipeline/pipeline_compiler.rs

@@ -5,9 +5,10 @@ use crate::{
 };
 use bevy_asset::{Assets, Handle};
 use bevy_property::{Properties, Property};
+use bevy_utils::{HashMap, HashSet};
 use once_cell::sync::Lazy;
 use serde::{Deserialize, Serialize};
-use std::collections::{HashMap, HashSet};
+
 #[derive(Clone, Eq, PartialEq, Debug, Properties)]
 pub struct PipelineSpecialization {
     pub shader_specialization: ShaderSpecialization,

crates/bevy_render/src/pipeline/pipeline_layout.rs

@@ -1,6 +1,7 @@
 use super::{BindGroupDescriptor, VertexBufferDescriptor, VertexBufferDescriptors};
 use crate::shader::{ShaderLayout, GL_VERTEX_INDEX};
-use std::{collections::HashMap, hash::Hash};
+use bevy_utils::HashMap;
+use std::hash::Hash;
 
 #[derive(Clone, Debug, Default)]
 pub struct PipelineLayout {
@@ -16,7 +17,7 @@ impl PipelineLayout {
     }
 
     pub fn from_shader_layouts(shader_layouts: &mut [ShaderLayout]) -> Self {
-        let mut bind_groups = HashMap::<u32, BindGroupDescriptor>::new();
+        let mut bind_groups = HashMap::<u32, BindGroupDescriptor>::default();
         let mut vertex_buffer_descriptors = Vec::new();
         for shader_layout in shader_layouts.iter_mut() {
             for shader_bind_group in shader_layout.bind_groups.iter_mut() {

crates/bevy_render/src/pipeline/vertex_buffer_descriptor.rs

@@ -1,5 +1,6 @@
 use super::VertexFormat;
-use std::{borrow::Cow, collections::HashMap};
+use bevy_utils::HashMap;
+use std::borrow::Cow;
 
 pub use bevy_derive::AsVertexBufferDescriptor;
 

crates/bevy_render/src/render_graph/graph.rs

@@ -1,7 +1,7 @@
 use super::{Edge, Node, NodeId, NodeLabel, NodeState, RenderGraphError, SlotLabel, SystemNode};
 use bevy_ecs::{Commands, Schedule};
-use std::{borrow::Cow, collections::HashMap, fmt::Debug};
+use bevy_utils::HashMap;
-
+use std::{borrow::Cow, fmt::Debug};
 pub struct RenderGraph {
     nodes: HashMap<NodeId, NodeState>,
     node_names: HashMap<Cow<'static, str>, NodeId>,
@@ -300,7 +300,8 @@ mod tests {
         renderer::{RenderContext, RenderResourceType},
     };
     use bevy_ecs::{Resources, World};
-    use std::{collections::HashSet, iter::FromIterator};
+    use bevy_utils::HashSet;
+    use std::iter::FromIterator;
 
     #[derive(Debug)]
     struct TestNode {

crates/bevy_render/src/render_graph/nodes/render_resources_node.rs

@@ -13,8 +13,9 @@ use bevy_asset::{Assets, Handle};
 use bevy_ecs::{
     Commands, Entity, IntoQuerySystem, Local, Query, Res, ResMut, Resources, System, World,
 };
+use bevy_utils::HashMap;
 use renderer::{AssetRenderResourceBindings, BufferId, RenderResourceType, RenderResources};
-use std::{collections::HashMap, hash::Hash, marker::PhantomData, ops::DerefMut};
+use std::{hash::Hash, marker::PhantomData, ops::DerefMut};
 
 pub const BIND_BUFFER_ALIGNMENT: usize = 256;
 
@@ -55,7 +56,7 @@ impl<I: Hash + Eq> BufferArray<I> {
             min_capacity,
             buffer: None,
             free_indices: Vec::new(),
-            indices: HashMap::new(),
+            indices: HashMap::default(),
         }
     }
 

crates/bevy_render/src/render_graph/schedule.rs

@@ -1,5 +1,5 @@
 use super::{NodeId, NodeState, RenderGraph, RenderGraphError};
-use std::collections::HashMap;
+use bevy_utils::HashMap;
 use thiserror::Error;
 
 #[derive(Error, Debug)]
@@ -161,7 +161,7 @@ impl RenderGraphStager for DependentNodeStager {
             .iter_nodes()
             .filter(|node| node.input_slots.is_empty());
         let mut stages = vec![Stage::default()];
-        let mut node_stages = HashMap::new();
+        let mut node_stages = HashMap::default();
         for output_only_node in output_only_nodes {
             // each "output only" node should start a new job on the first stage
             stage_node(

crates/bevy_render/src/renderer/headless_render_resource_context.rs

@@ -6,9 +6,10 @@ use crate::{
     texture::{SamplerDescriptor, TextureDescriptor},
 };
 use bevy_asset::{Assets, Handle, HandleUntyped};
+use bevy_utils::HashMap;
 use bevy_window::Window;
 use parking_lot::RwLock;
-use std::{collections::HashMap, ops::Range, sync::Arc};
+use std::{ops::Range, sync::Arc};
 
 #[derive(Default)]
 pub struct HeadlessRenderResourceContext {

crates/bevy_render/src/renderer/render_resource/bind_group.rs

@@ -1,6 +1,6 @@
 use super::{BufferId, RenderResourceBinding, SamplerId, TextureId};
+use bevy_utils::AHasher;
 use std::{
-    collections::hash_map::DefaultHasher,
     hash::{Hash, Hasher},
     ops::Range,
     sync::Arc,
@@ -32,7 +32,7 @@ impl BindGroup {
 pub struct BindGroupBuilder {
     pub indexed_bindings: Vec<IndexedBindGroupEntry>,
     pub dynamic_uniform_indices: Vec<u32>,
-    pub hasher: DefaultHasher,
+    pub hasher: AHasher,
 }
 
 impl BindGroupBuilder {

crates/bevy_render/src/renderer/render_resource/render_resource_bindings.rs

@@ -4,11 +4,8 @@ use crate::{
     renderer::RenderResourceContext,
 };
 use bevy_asset::{Handle, HandleUntyped};
-use std::{
+use bevy_utils::{HashMap, HashSet};
-    collections::{HashMap, HashSet},
+use std::{hash::Hash, ops::Range};
-    hash::Hash,
-    ops::Range,
-};
 use uuid::Uuid;
 
 #[derive(Clone, Eq, Debug)]

crates/bevy_render/src/shader/shader_reflect.rs

@@ -6,6 +6,7 @@ use crate::{
     texture::{TextureComponentType, TextureViewDimension},
 };
 use bevy_core::AsBytes;
+use bevy_utils::HashSet;
 use spirv_reflect::{
     types::{
         ReflectDescriptorBinding, ReflectDescriptorSet, ReflectDescriptorType, ReflectDimension,
@@ -14,7 +15,6 @@ use spirv_reflect::{
     },
     ShaderModule,
 };
-use std::collections::HashSet;
 
 /// Defines the memory layout of a shader
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -51,7 +51,7 @@ impl ShaderLayout {
                 vertex_attribute_descriptors
                     .sort_by(|a, b| a.shader_location.cmp(&b.shader_location));
 
-                let mut visited_buffer_descriptors = HashSet::new();
+                let mut visited_buffer_descriptors = HashSet::default();
                 let mut vertex_buffer_descriptors = Vec::new();
                 let mut current_descriptor: Option<VertexBufferDescriptor> = None;
                 for vertex_attribute_descriptor in vertex_attribute_descriptors.drain(..) {

crates/bevy_render/src/texture/texture.rs

@@ -6,7 +6,7 @@ use bevy_app::prelude::{EventReader, Events};
 use bevy_asset::{AssetEvent, Assets, Handle};
 use bevy_ecs::{Res, ResMut};
 use bevy_math::Vec2;
-use std::collections::HashSet;
+use bevy_utils::HashSet;
 
 pub const TEXTURE_ASSET_INDEX: usize = 0;
 pub const SAMPLER_ASSET_INDEX: usize = 1;
@@ -78,7 +78,7 @@ impl Texture {
         texture_events: Res<Events<AssetEvent<Texture>>>,
     ) {
         let render_resource_context = &**render_resource_context;
-        let mut changed_textures = HashSet::new();
+        let mut changed_textures = HashSet::default();
         for event in state.event_reader.iter(&texture_events) {
             match event {
                 AssetEvent::Created { handle } => {

crates/bevy_ron/Cargo.toml

@@ -22,6 +22,7 @@ exclude = ["bors.toml", ".travis.yml"]
 name = "bevy_ron"
 
 [dependencies]
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 base64 = "0.12"
 bitflags = "1.0.4"
 indexmap = { version = "1.0.2", features = ["serde-1"], optional = true }
@@ -29,4 +30,4 @@ serde = { version = "1.0.60", features = ["serde_derive"] }
 
 [dev-dependencies]
 serde_bytes = "0.11"
-serde_json = "1"
+serde_json = "1"

crates/bevy_ron/src/de/tests.rs

@@ -83,9 +83,9 @@ fn test_array() {
 
 #[test]
 fn test_map() {
-    use std::collections::HashMap;
+    use bevy_utils::HashMap;
 
-    let mut map = HashMap::new();
+    let mut map = HashMap::default();
     map.insert((true, false), 4);
     map.insert((false, false), 123);
 
@@ -159,7 +159,7 @@ fn err<T>(kind: ErrorCode, line: usize, col: usize) -> Result<T> {
 #[test]
 fn test_err_wrong_value() {
     use self::ErrorCode::*;
-    use std::collections::HashMap;
+    use bevy_utils::HashMap;
 
     assert_eq!(from_str::<f32>("'c'"), err(ExpectedFloat, 1, 1));
     assert_eq!(from_str::<String>("'c'"), err(ExpectedString, 1, 1));

crates/bevy_ron/src/ser/mod.rs

@@ -958,9 +958,9 @@ mod tests {
 
     #[test]
     fn test_map() {
-        use std::collections::HashMap;
+        use bevy_utils::HashMap;
 
-        let mut map = HashMap::new();
+        let mut map = HashMap::default();
         map.insert((true, false), 4);
         map.insert((false, false), 123);
 

crates/bevy_scene/Cargo.toml

@@ -16,6 +16,7 @@ bevy_asset = { path = "../bevy_asset", version = "0.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_property = { path = "../bevy_property", version = "0.1" }
 bevy_type_registry = { path = "../bevy_type_registry", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 serde = { version = "1.0", features = ["derive"]}

crates/bevy_scene/src/scene_spawner.rs

@@ -3,7 +3,7 @@ use bevy_app::prelude::*;
 use bevy_asset::{AssetEvent, Assets, Handle};
 use bevy_ecs::{Resources, World};
 use bevy_type_registry::TypeRegistry;
-use std::collections::{HashMap, HashSet};
+use bevy_utils::{HashMap, HashSet};
 use thiserror::Error;
 use uuid::Uuid;
 

crates/bevy_sprite/Cargo.toml

@@ -19,6 +19,7 @@ bevy_math = { path = "../bevy_math", version = "0.1" }
 bevy_render = { path = "../bevy_render", version = "0.1" }
 bevy_transform = { path = "../bevy_transform", version = "0.1" }
 bevy_type_registry = { path = "../bevy_type_registry", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 rectangle-pack = "0.1"

crates/bevy_sprite/src/texture_atlas.rs

@@ -7,7 +7,7 @@ use bevy_render::{
     renderer::{RenderResource, RenderResources},
     texture::Texture,
 };
-use std::collections::HashMap;
+use bevy_utils::HashMap;
 
 /// An atlas containing multiple textures (like a spritesheet or a tilemap)
 #[derive(RenderResources)]

crates/bevy_sprite/src/texture_atlas_builder.rs

@@ -2,11 +2,11 @@ use crate::{Rect, TextureAtlas};
 use bevy_asset::{Assets, Handle};
 use bevy_math::Vec2;
 use bevy_render::texture::{Texture, TextureFormat};
+use bevy_utils::HashMap;
 use rectangle_pack::{
     contains_smallest_box, pack_rects, volume_heuristic, GroupedRectsToPlace, PackedLocation,
     RectToInsert, TargetBin,
 };
-use std::collections::HashMap;
 use thiserror::Error;
 
 pub struct TextureAtlasBuilder {
@@ -88,7 +88,7 @@ impl TextureAtlasBuilder {
                 rect_placements = None;
                 break;
             }
-            let mut target_bins = HashMap::new();
+            let mut target_bins = std::collections::HashMap::new();
             target_bins.insert(0, TargetBin::new(current_width, current_height, 1));
             atlas_texture = Texture::new_fill(
                 Vec2::new(current_width as f32, current_height as f32),
@@ -113,7 +113,7 @@ impl TextureAtlasBuilder {
         let rect_placements = rect_placements.ok_or_else(|| RectanglePackError::NotEnoughSpace)?;
 
         let mut texture_rects = Vec::with_capacity(rect_placements.packed_locations().len());
-        let mut texture_handles = HashMap::new();
+        let mut texture_handles = HashMap::default();
         for (texture_handle, (_, packed_location)) in rect_placements.packed_locations().iter() {
             let texture = textures.get(texture_handle).unwrap();
             let min = Vec2::new(packed_location.x() as f32, packed_location.y() as f32);

crates/bevy_text/Cargo.toml

@@ -17,6 +17,7 @@ bevy_core = { path = "../bevy_core", version = "0.1" }
 bevy_math = { path = "../bevy_math", version = "0.1" }
 bevy_render = { path = "../bevy_render", version = "0.1" }
 bevy_sprite = { path = "../bevy_sprite", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 ab_glyph = "0.2.2"

crates/bevy_text/src/font_atlas.rs

@@ -2,7 +2,7 @@ use bevy_asset::{Assets, Handle};
 use bevy_math::Vec2;
 use bevy_render::texture::{Texture, TextureFormat};
 use bevy_sprite::{DynamicTextureAtlasBuilder, TextureAtlas};
-use std::collections::HashMap;
+use bevy_utils::HashMap;
 
 pub struct FontAtlas {
     pub dynamic_texture_atlas_builder: DynamicTextureAtlasBuilder,
@@ -24,7 +24,7 @@ impl FontAtlas {
         let texture_atlas = TextureAtlas::new_empty(atlas_texture, size);
         Self {
             texture_atlas: texture_atlases.add(texture_atlas),
-            glyph_to_index: HashMap::new(),
+            glyph_to_index: HashMap::default(),
             dynamic_texture_atlas_builder: DynamicTextureAtlasBuilder::new(size, 1),
         }
     }

crates/bevy_text/src/font_atlas_set.rs

@@ -5,7 +5,7 @@ use bevy_core::FloatOrd;
 use bevy_math::Vec2;
 use bevy_render::texture::Texture;
 use bevy_sprite::TextureAtlas;
-use std::collections::HashMap;
+use bevy_utils::HashMap;
 
 // work around rust's f32 order/hash limitations
 type FontSizeKey = FloatOrd;
@@ -26,7 +26,7 @@ impl FontAtlasSet {
     pub fn new(font: Handle<Font>) -> Self {
         Self {
             font,
-            font_atlases: HashMap::new(),
+            font_atlases: HashMap::default(),
         }
     }
 

crates/bevy_transform/Cargo.toml

@@ -16,8 +16,8 @@ bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_math = { path = "../bevy_math", version = "0.1" }
 bevy_property = { path =  "../bevy_property", version = "0.1" }
 bevy_type_registry = { path =  "../bevy_type_registry", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 log = "0.4"
-smallvec = { version = "1.4", features = ["serde"] }
+smallvec = { version = "1.4", features = ["serde"] }
-

crates/bevy_transform/src/hierarchy/hierarchy_maintenance_system.rs

@@ -1,7 +1,7 @@
 use crate::components::*;
 use bevy_ecs::{Commands, Entity, IntoQuerySystem, Query, System, Without};
+use bevy_utils::HashMap;
 use smallvec::SmallVec;
-use std::collections::HashMap;
 
 pub fn missing_previous_parent_system(
     mut commands: Commands,
@@ -36,7 +36,7 @@ pub fn parent_update_system(
     }
 
     // Tracks all newly created `Children` Components this frame.
-    let mut children_additions = HashMap::<Entity, SmallVec<[Entity; 8]>>::new();
+    let mut children_additions = HashMap::<Entity, SmallVec<[Entity; 8]>>::default();
 
     // Entities with a changed Parent (that also have a PreviousParent, even if None)
     for (entity, parent, mut previous_parent) in &mut changed_parent_query.iter() {

crates/bevy_type_registry/Cargo.toml

@@ -14,6 +14,7 @@ keywords = ["bevy"]
 bevy_app = { path = "../bevy_app", version = "0.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_property = { path = "../bevy_property", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 serde = { version = "1", features = ["derive"] }

crates/bevy_type_registry/src/type_registry.rs

@@ -1,11 +1,8 @@
 use bevy_ecs::{Archetype, Component, Entity, FromResources, Resources, World};
 use bevy_property::{Properties, Property, PropertyTypeRegistration, PropertyTypeRegistry};
+use bevy_utils::{HashMap, HashSet};
 use parking_lot::RwLock;
-use std::{
+use std::{any::TypeId, sync::Arc};
-    any::TypeId,
-    collections::{HashMap, HashSet},
-    sync::Arc,
-};
 
 #[derive(Clone, Default)]
 pub struct TypeRegistry {

crates/bevy_ui/Cargo.toml

@@ -24,6 +24,7 @@ bevy_text = { path = "../bevy_text", version = "0.1" }
 bevy_transform = { path = "../bevy_transform", version = "0.1" }
 bevy_type_registry = { path = "../bevy_type_registry", version = "0.1" }
 bevy_window = { path = "../bevy_window", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 stretch = "0.3"

crates/bevy_ui/src/flex/mod.rs

@@ -4,8 +4,8 @@ use crate::{CalculatedSize, Node, Style};
 use bevy_ecs::{Changed, Entity, Query, Res, ResMut, With, Without};
 use bevy_math::Vec2;
 use bevy_transform::prelude::{Children, LocalTransform, Parent};
+use bevy_utils::HashMap;
 use bevy_window::{Window, WindowId, Windows};
-use std::collections::HashMap;
 use stretch::{number::Number, Stretch};
 
 pub struct FlexSurface {

crates/bevy_utils/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "bevy_utils"
+version = "0.1.3"
+edition = "2018"
+authors = ["Bevy Contributors <bevyengine@gmail.com>", "Carter Anderson <mcanders1@gmail.com>"]
+description = "A collection of utils for Bevy Engine"
+homepage = "https://bevyengine.org"
+repository = "https://github.com/bevyengine/bevy"
+license = "MIT"
+keywords = ["bevy"]
+
+[dependencies]
+ahash = "0.4.4"

crates/bevy_utils/src/lib.rs

@@ -0,0 +1,15 @@
+pub use ahash::AHasher;
+use ahash::RandomState;
+
+pub type HashMap<K, V> = std::collections::HashMap<K, V, RandomState>;
+pub type HashSet<K> = std::collections::HashSet<K, RandomState>;
+
+pub trait HashMapExt {
+    fn with_capacity(cap: usize) -> Self;
+}
+
+impl<K, V> HashMapExt for HashMap<K, V> {
+    fn with_capacity(cap: usize) -> Self {
+        HashMap::with_capacity_and_hasher(cap, RandomState::default())
+    }
+}

crates/bevy_wgpu/Cargo.toml

@@ -23,6 +23,7 @@ bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_render = { path = "../bevy_render", version = "0.1" }
 bevy_window = { path = "../bevy_window", version = "0.1" }
 bevy_winit = { path = "../bevy_winit", optional = true, version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 wgpu = "0.6"

crates/bevy_wgpu/src/renderer/wgpu_render_graph_executor.rs

@@ -4,8 +4,9 @@ use bevy_render::{
     render_graph::{Edge, NodeId, ResourceSlots, StageBorrow},
     renderer::RenderResourceContext,
 };
+use bevy_utils::HashMap;
 use parking_lot::RwLock;
-use std::{collections::HashMap, sync::Arc};
+use std::sync::Arc;
 
 pub struct WgpuRenderGraphExecutor {
     pub max_thread_count: usize,

crates/bevy_wgpu/src/wgpu_resources.rs

@@ -5,9 +5,10 @@ use bevy_render::{
     shader::Shader,
     texture::TextureDescriptor,
 };
+use bevy_utils::HashMap;
 use bevy_window::WindowId;
 use parking_lot::{RwLock, RwLockReadGuard};
-use std::{collections::HashMap, sync::Arc};
+use std::sync::Arc;
 
 #[derive(Default)]
 pub struct WgpuBindGroupInfo {

crates/bevy_window/Cargo.toml

@@ -14,6 +14,7 @@ keywords = ["bevy"]
 bevy_app = { path = "../bevy_app", version = "0.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_math = { path = "../bevy_math", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 uuid = { version = "0.8", features = ["v4", "serde"] }

crates/bevy_window/src/windows.rs

@@ -1,5 +1,5 @@
 use super::{Window, WindowId};
-use std::collections::HashMap;
+use bevy_utils::HashMap;
 
 #[derive(Default)]
 pub struct Windows {

crates/bevy_winit/Cargo.toml

@@ -20,6 +20,7 @@ bevy_ecs = { path = "../bevy_ecs", version = "0.1" }
 bevy_input = { path = "../bevy_input", version = "0.1" }
 bevy_math = { path = "../bevy_math", version = "0.1" }
 bevy_window = { path = "../bevy_window", version = "0.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.1" }
 
 # other
 winit = { version = "0.22.2", package = "cart-tmp-winit", default-features = false}

crates/bevy_winit/src/winit_windows.rs

@@ -1,5 +1,5 @@
+use bevy_utils::HashMap;
 use bevy_window::{Window, WindowId, WindowMode};
-use std::collections::HashMap;
 
 #[derive(Default)]
 pub struct WinitWindows {