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Use SlotMaps to store systems and system sets in Schedules #19352

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c0aac3f
slotmaps
ItsDoot May 24, 2025
bfed18a
fix ci
ItsDoot May 24, 2025
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1 change: 1 addition & 0 deletions crates/bevy_ecs/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,7 @@ variadics_please = { version = "1.1", default-features = false }
tracing = { version = "0.1", default-features = false, optional = true }
log = { version = "0.4", default-features = false }
bumpalo = "3"
slotmap = { version = "1.0.7", default-features = false }

concurrent-queue = { version = "2.5.0", default-features = false }
[target.'cfg(not(all(target_has_atomic = "8", target_has_atomic = "16", target_has_atomic = "32", target_has_atomic = "64", target_has_atomic = "ptr")))'.dependencies]
Expand Down
128 changes: 76 additions & 52 deletions crates/bevy_ecs/src/schedule/auto_insert_apply_deferred.rs
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Expand Up @@ -2,8 +2,9 @@ use alloc::{boxed::Box, collections::BTreeSet, vec::Vec};

use bevy_platform::collections::HashMap;

use crate::system::IntoSystem;
use crate::schedule::SystemSetKey;
use crate::world::World;
use crate::{schedule::SystemKey, system::IntoSystem};

use super::{
is_apply_deferred, ApplyDeferred, DiGraph, Direction, NodeId, ReportCycles, ScheduleBuildError,
Expand Down Expand Up @@ -37,28 +38,26 @@ impl AutoInsertApplyDeferredPass {
.get(&distance)
.copied()
.or_else(|| {
let node_id = self.add_auto_sync(graph);
let node_id = NodeId::System(self.add_auto_sync(graph));
self.auto_sync_node_ids.insert(distance, node_id);
Some(node_id)
})
.unwrap()
}
/// add an [`ApplyDeferred`] system with no config
fn add_auto_sync(&mut self, graph: &mut ScheduleGraph) -> NodeId {
let id = NodeId::System(graph.systems.len());

graph
fn add_auto_sync(&mut self, graph: &mut ScheduleGraph) -> SystemKey {
let key = graph
.systems
.push(SystemNode::new(Box::new(IntoSystem::into_system(
.insert(SystemNode::new(Box::new(IntoSystem::into_system(
ApplyDeferred,
))));
graph.system_conditions.push(Vec::new());
graph.system_conditions.insert(key, Vec::new());

// ignore ambiguities with auto sync points
// They aren't under user control, so no one should know or care.
graph.ambiguous_with_all.insert(id);
graph.ambiguous_with_all.insert(NodeId::System(key));

id
key
}
}

Expand All @@ -80,76 +79,90 @@ impl ScheduleBuildPass for AutoInsertApplyDeferredPass {
let mut sync_point_graph = dependency_flattened.clone();
let topo = graph.topsort_graph(dependency_flattened, ReportCycles::Dependency)?;

fn set_has_conditions(graph: &ScheduleGraph, node: NodeId) -> bool {
!graph.set_conditions_at(node).is_empty()
fn set_has_conditions(graph: &ScheduleGraph, set: SystemSetKey) -> bool {
!graph.set_conditions_at(set).is_empty()
|| graph
.hierarchy()
.graph()
.edges_directed(node, Direction::Incoming)
.any(|(parent, _)| set_has_conditions(graph, parent))
.edges_directed(NodeId::Set(set), Direction::Incoming)
.any(|(parent, _)| {
parent
.as_set()
.is_some_and(|p| set_has_conditions(graph, p))
})
}

fn system_has_conditions(graph: &ScheduleGraph, node: NodeId) -> bool {
assert!(node.is_system());
!graph.system_conditions[node.index()].is_empty()
fn system_has_conditions(graph: &ScheduleGraph, key: SystemKey) -> bool {
!graph.system_conditions[key].is_empty()
|| graph
.hierarchy()
.graph()
.edges_directed(node, Direction::Incoming)
.any(|(parent, _)| set_has_conditions(graph, parent))
.edges_directed(NodeId::System(key), Direction::Incoming)
.any(|(parent, _)| {
parent
.as_set()
.is_some_and(|p| set_has_conditions(graph, p))
})
}

let mut system_has_conditions_cache = HashMap::<usize, bool>::default();
let mut is_valid_explicit_sync_point = |system: NodeId| {
let index = system.index();
is_apply_deferred(graph.systems[index].get().unwrap())
let mut system_has_conditions_cache = HashMap::<SystemKey, bool>::default();
let mut is_valid_explicit_sync_point = |key: SystemKey| {
is_apply_deferred(graph.systems[key].get().unwrap())
&& !*system_has_conditions_cache
.entry(index)
.or_insert_with(|| system_has_conditions(graph, system))
.entry(key)
.or_insert_with(|| system_has_conditions(graph, key))
};

// Calculate the distance for each node.
// The "distance" is the number of sync points between a node and the beginning of the graph.
// Also store if a preceding edge would have added a sync point but was ignored to add it at
// a later edge that is not ignored.
let mut distances_and_pending_sync: HashMap<usize, (u32, bool)> =
let mut distances_and_pending_sync: HashMap<SystemKey, (u32, bool)> =
HashMap::with_capacity_and_hasher(topo.len(), Default::default());

// Keep track of any explicit sync nodes for a specific distance.
let mut distance_to_explicit_sync_node: HashMap<u32, NodeId> = HashMap::default();

// Determine the distance for every node and collect the explicit sync points.
for node in &topo {
let &NodeId::System(key) = node else {
continue;
};

let (node_distance, mut node_needs_sync) = distances_and_pending_sync
.get(&node.index())
.get(&key)
.copied()
.unwrap_or_default();

if is_valid_explicit_sync_point(*node) {
if is_valid_explicit_sync_point(key) {
// The distance of this sync point does not change anymore as the iteration order
// makes sure that this node is no unvisited target of another node.
// Because of this, the sync point can be stored for this distance to be reused as
// automatically added sync points later.
distance_to_explicit_sync_node.insert(node_distance, *node);
distance_to_explicit_sync_node.insert(node_distance, NodeId::System(key));

// This node just did a sync, so the only reason to do another sync is if one was
// explicitly scheduled afterwards.
node_needs_sync = false;
} else if !node_needs_sync {
// No previous node has postponed sync points to add so check if the system itself
// has deferred params that require a sync point to apply them.
node_needs_sync = graph.systems[node.index()].get().unwrap().has_deferred();
node_needs_sync = graph.systems[key].get().unwrap().has_deferred();
}

for target in dependency_flattened.neighbors_directed(*node, Direction::Outgoing) {
let (target_distance, target_pending_sync) = distances_and_pending_sync
.entry(target.index())
.or_default();
let NodeId::System(target) = target else {
continue;
};
let (target_distance, target_pending_sync) =
distances_and_pending_sync.entry(target).or_default();

let mut edge_needs_sync = node_needs_sync;
if node_needs_sync
&& !graph.systems[target.index()].get().unwrap().is_exclusive()
&& self.no_sync_edges.contains(&(*node, target))
&& !graph.systems[target].get().unwrap().is_exclusive()
&& self
.no_sync_edges
.contains(&(*node, NodeId::System(target)))
{
// The node has deferred params to apply, but this edge is ignoring sync points.
// Mark the target as 'delaying' those commands to a future edge and the current
Expand All @@ -174,14 +187,20 @@ impl ScheduleBuildPass for AutoInsertApplyDeferredPass {
// Find any edges which have a different number of sync points between them and make sure
// there is a sync point between them.
for node in &topo {
let &NodeId::System(key) = node else {
continue;
};
let (node_distance, _) = distances_and_pending_sync
.get(&node.index())
.get(&key)
.copied()
.unwrap_or_default();

for target in dependency_flattened.neighbors_directed(*node, Direction::Outgoing) {
let NodeId::System(target) = target else {
continue;
};
let (target_distance, _) = distances_and_pending_sync
.get(&target.index())
.get(&target)
.copied()
.unwrap_or_default();

Expand All @@ -190,7 +209,7 @@ impl ScheduleBuildPass for AutoInsertApplyDeferredPass {
continue;
}

if is_apply_deferred(graph.systems[target.index()].get().unwrap()) {
if is_apply_deferred(graph.systems[target].get().unwrap()) {
// We don't need to insert a sync point since ApplyDeferred is a sync point
// already!
continue;
Expand All @@ -202,10 +221,10 @@ impl ScheduleBuildPass for AutoInsertApplyDeferredPass {
.unwrap_or_else(|| self.get_sync_point(graph, target_distance));

sync_point_graph.add_edge(*node, sync_point);
sync_point_graph.add_edge(sync_point, target);
sync_point_graph.add_edge(sync_point, NodeId::System(target));

// The edge without the sync point is now redundant.
sync_point_graph.remove_edge(*node, target);
sync_point_graph.remove_edge(*node, NodeId::System(target));
}
}

Expand All @@ -215,34 +234,39 @@ impl ScheduleBuildPass for AutoInsertApplyDeferredPass {

fn collapse_set(
&mut self,
set: NodeId,
systems: &[NodeId],
set: SystemSetKey,
systems: &[SystemKey],
dependency_flattened: &DiGraph,
) -> impl Iterator<Item = (NodeId, NodeId)> {
if systems.is_empty() {
// collapse dependencies for empty sets
for a in dependency_flattened.neighbors_directed(set, Direction::Incoming) {
for b in dependency_flattened.neighbors_directed(set, Direction::Outgoing) {
if self.no_sync_edges.contains(&(a, set))
&& self.no_sync_edges.contains(&(set, b))
for a in dependency_flattened.neighbors_directed(NodeId::Set(set), Direction::Incoming)
{
for b in
dependency_flattened.neighbors_directed(NodeId::Set(set), Direction::Outgoing)
{
if self.no_sync_edges.contains(&(a, NodeId::Set(set)))
&& self.no_sync_edges.contains(&(NodeId::Set(set), b))
{
self.no_sync_edges.insert((a, b));
}
}
}
} else {
for a in dependency_flattened.neighbors_directed(set, Direction::Incoming) {
for a in dependency_flattened.neighbors_directed(NodeId::Set(set), Direction::Incoming)
{
for &sys in systems {
if self.no_sync_edges.contains(&(a, set)) {
self.no_sync_edges.insert((a, sys));
if self.no_sync_edges.contains(&(a, NodeId::Set(set))) {
self.no_sync_edges.insert((a, NodeId::System(sys)));
}
}
}

for b in dependency_flattened.neighbors_directed(set, Direction::Outgoing) {
for b in dependency_flattened.neighbors_directed(NodeId::Set(set), Direction::Outgoing)
{
for &sys in systems {
if self.no_sync_edges.contains(&(set, b)) {
self.no_sync_edges.insert((sys, b));
if self.no_sync_edges.contains(&(NodeId::Set(set), b)) {
self.no_sync_edges.insert((NodeId::System(sys), b));
}
}
}
Expand Down
6 changes: 3 additions & 3 deletions crates/bevy_ecs/src/schedule/executor/mod.rs
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Expand Up @@ -20,7 +20,7 @@ use crate::{
error::{BevyError, ErrorContext, Result},
prelude::{IntoSystemSet, SystemSet},
query::{Access, FilteredAccessSet},
schedule::{BoxedCondition, InternedSystemSet, NodeId, SystemTypeSet},
schedule::{BoxedCondition, InternedSystemSet, SystemKey, SystemSetKey, SystemTypeSet},
system::{ScheduleSystem, System, SystemIn, SystemParamValidationError},
world::{unsafe_world_cell::UnsafeWorldCell, DeferredWorld, World},
};
Expand Down Expand Up @@ -73,7 +73,7 @@ pub enum ExecutorKind {
#[derive(Default)]
pub struct SystemSchedule {
/// List of system node ids.
pub(super) system_ids: Vec<NodeId>,
pub(super) system_ids: Vec<SystemKey>,
/// Indexed by system node id.
pub(super) systems: Vec<ScheduleSystem>,
/// Indexed by system node id.
Expand All @@ -96,7 +96,7 @@ pub struct SystemSchedule {
/// List of sets containing the system that have conditions
pub(super) sets_with_conditions_of_systems: Vec<FixedBitSet>,
/// List of system set node ids.
pub(super) set_ids: Vec<NodeId>,
pub(super) set_ids: Vec<SystemSetKey>,
/// Indexed by system set node id.
pub(super) set_conditions: Vec<Vec<BoxedCondition>>,
/// Indexed by system set node id.
Expand Down
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