optimizations at high entity counts

Author: mat-1

CONTRIBUTING.md

@@ -18,6 +18,8 @@ If you're working with low-level physics or packet related code, it's quite easy
 
 The second major thing to watch out for is accidentally introducing performance regressions. Certain parts of Azalea are highly performance sensitive (notably, the pathfinder), so most changes in these areas should be benchmarked to avoid accidentally hurting performance.
 
+You're encouraged to write relevant tests and benchmarks.
+
 ## Profiling
 
 Please see [the chapter about profiling in the Rust performance book](https://nnethercote.github.io/perf-book/profiling.html).
@@ -29,12 +31,10 @@ cargo install flamegraph
 RUSTFLAGS="-C force-frame-pointers=yes" cargo r -r --example testbot
 # wait a few seconds so chunks being loaded doesn't affect the flamegraph, and
 # then run this in a separate window:
-flamegraph -p $(pidof testbot)
+flamegraph -p $(pidof testbot) --deterministic
 # wait about 15 seconds, then ctrl+c, and view the flamegraph.svg
 ```
 
 ## AI Policy
 
 Please avoid using generative AI to make contributions to Azalea. We do not enjoy working with code that wasn't written by people.
-
-

Cargo.toml

@@ -135,7 +135,7 @@ cargo-args = ["-Zunstable-options", "-Zrustdoc-scrape-examples"]
 # --- Profile Settings ---
 
 [profile.release]
-debug = true
+debug = "line-tables-only"
 
 # decoding packets takes forever if we don't do this
 [profile.dev.package.azalea-crypto]

azalea-client/src/plugins/packet/game/mod.rs

@@ -9,7 +9,7 @@ use azalea_core::{
 };
 use azalea_entity::{
     ActiveEffects, Dead, EntityBundle, EntityKindComponent, HasClientLoaded, LoadedBy, LocalEntity,
-    LookDirection, Physics, PlayerAbilities, Position, RelativeEntityUpdate,
+    LookDirection, Physics, PlayerAbilities, Position,
     indexing::{EntityIdIndex, EntityUuidIndex},
     inventory::Inventory,
     metadata::{Health, apply_metadata},
@@ -36,7 +36,10 @@ use crate::{
     inventory::{ClientsideCloseContainerEvent, MenuOpenedEvent, SetContainerContentEvent},
     local_player::{Experience, Hunger, LocalGameMode, TabList, WorldHolder},
     movement::{KnockbackData, KnockbackEvent},
-    packet::{as_system, declare_packet_handlers},
+    packet::{
+        as_system, declare_packet_handlers,
+        relative_updates::{EntityUpdateQuery, RelativeEntityUpdate, should_apply_entity_update},
+    },
     player::{GameProfileComponent, PlayerInfo},
     tick_counter::TicksConnected,
 };
@@ -716,36 +719,37 @@ impl GamePacketHandler<'_> {
         // vanilla servers use this packet for knockback, but note that the Explode
         // packet is also sometimes used by servers for knockback
 
-        as_system::<(Commands, Query<(&EntityIdIndex, &WorldHolder)>)>(
-            self.ecs,
-            |(mut commands, query)| {
-                let (entity_id_index, world_holder) = query.get(self.player).unwrap();
-
-                let Some(entity) = entity_id_index.get_by_minecraft_entity(p.id) else {
-                    // note that this log (and some other ones like the one in RemoveEntities)
-                    // sometimes happens when killing mobs. it seems to be a vanilla bug, which is
-                    // why it's a debug log instead of a warning
-                    debug!(
-                        "Got set entity motion packet for unknown entity id {}",
-                        p.id
-                    );
-                    return;
-                };
-
-                // this is to make sure the same entity velocity update doesn't get sent
-                // multiple times when in swarms
+        as_system::<(
+            Commands,
+            Query<(&EntityIdIndex, &WorldHolder)>,
+            EntityUpdateQuery,
+        )>(self.ecs, |(mut commands, query, entity_update_query)| {
+            let (entity_id_index, world_holder) = query.get(self.player).unwrap();
 
-                let data = KnockbackData::Set(p.delta.to_vec3());
+            let Some(entity) = entity_id_index.get_by_minecraft_entity(p.id) else {
+                // note that this log (and some other ones like the one in RemoveEntities)
+                // sometimes happens when killing mobs. it seems to be a vanilla bug, which is
+                // why it's a debug log instead of a warning
+                debug!(
+                    "Got set entity motion packet for unknown entity id {}",
+                    p.id
+                );
+                return;
+            };
 
-                commands.entity(entity).queue(RelativeEntityUpdate::new(
-                    world_holder.partial.clone(),
-                    move |entity_mut| {
-                        entity_mut
-                            .world_scope(|world| world.trigger(KnockbackEvent { entity, data }));
-                    },
-                ));
-            },
-        );
+            let data = KnockbackData::Set(p.delta.to_vec3());
+
+            // this is to make sure the same entity velocity update doesn't get sent
+            // multiple times when in swarms
+            if should_apply_entity_update(
+                &mut commands,
+                &mut world_holder.partial.write(),
+                entity,
+                entity_update_query,
+            ) {
+                commands.trigger(KnockbackEvent { entity, data });
+            }
+        });
     }
 
     pub fn set_entity_link(&mut self, p: &ClientboundSetEntityLink) {
@@ -795,8 +799,8 @@ impl GamePacketHandler<'_> {
 
         as_system::<(Commands, Query<(&EntityIdIndex, &WorldHolder)>)>(
             self.ecs,
-            |(mut commands, mut query)| {
-                let (entity_id_index, world_holder) = query.get_mut(self.player).unwrap();
+            |(mut commands, query)| {
+                let (entity_id_index, world_holder) = query.get(self.player).unwrap();
 
                 let Some(entity) = entity_id_index.get_by_minecraft_entity(p.id) else {
                     warn!("Got teleport entity packet for unknown entity id {}", p.id);
@@ -840,8 +844,8 @@ impl GamePacketHandler<'_> {
     pub fn move_entity_pos(&mut self, p: &ClientboundMoveEntityPos) {
         as_system::<(Commands, Query<(&EntityIdIndex, &WorldHolder)>)>(
             self.ecs,
-            |(mut commands, mut query)| {
-                let (entity_id_index, world_holder) = query.get_mut(self.player).unwrap();
+            |(mut commands, query)| {
+                let (entity_id_index, world_holder) = query.get(self.player).unwrap();
 
                 debug!("Got move entity pos packet {p:?}");
 
@@ -879,8 +883,8 @@ impl GamePacketHandler<'_> {
     pub fn move_entity_pos_rot(&mut self, p: &ClientboundMoveEntityPosRot) {
         as_system::<(Commands, Query<(&EntityIdIndex, &WorldHolder)>)>(
             self.ecs,
-            |(mut commands, mut query)| {
-                let (entity_id_index, world_holder) = query.get_mut(self.player).unwrap();
+            |(mut commands, query)| {
+                let (entity_id_index, world_holder) = query.get(self.player).unwrap();
 
                 debug!("Got move entity pos rot packet {p:?}");
 
@@ -929,8 +933,8 @@ impl GamePacketHandler<'_> {
     pub fn move_entity_rot(&mut self, p: &ClientboundMoveEntityRot) {
         as_system::<(Commands, Query<(&EntityIdIndex, &WorldHolder)>)>(
             self.ecs,
-            |(mut commands, mut query)| {
-                let (entity_id_index, world_holder) = query.get_mut(self.player).unwrap();
+            |(mut commands, query)| {
+                let (entity_id_index, world_holder) = query.get(self.player).unwrap();
 
                 let entity = entity_id_index.get_by_minecraft_entity(p.entity_id);
                 if let Some(entity) = entity {
@@ -1527,10 +1531,28 @@ impl GamePacketHandler<'_> {
     }
 
     pub fn entity_position_sync(&mut self, p: &ClientboundEntityPositionSync) {
-        as_system::<(Commands, Query<(&EntityIdIndex, &WorldHolder)>)>(
+        as_system::<(
+            Commands,
+            Query<(
+                &EntityIdIndex,
+                &WorldHolder,
+                Option<&LocalEntity>,
+                &mut Physics,
+                &mut Position,
+                &mut LookDirection,
+            )>,
+            EntityUpdateQuery,
+        )>(
             self.ecs,
-            |(mut commands, mut query)| {
-                let (entity_id_index, world_holder) = query.get_mut(self.player).unwrap();
+            |(mut commands, mut query, entity_update_query)| {
+                let (
+                    entity_id_index,
+                    world_holder,
+                    local_entity,
+                    mut physics,
+                    mut position,
+                    mut look_direction,
+                ) = query.get_mut(self.player).unwrap();
 
                 let Some(entity) = entity_id_index.get_by_minecraft_entity(p.id) else {
                     debug!("Got teleport entity packet for unknown entity id {}", p.id);
@@ -1541,28 +1563,32 @@ impl GamePacketHandler<'_> {
                 let new_on_ground = p.on_ground;
                 let new_look_direction = p.values.look_direction;
 
-                commands.entity(entity).queue(RelativeEntityUpdate::new(
-                    world_holder.partial.clone(),
-                    move |entity_mut| {
-                        let is_local_entity = entity_mut.get::<LocalEntity>().is_some();
-                        let mut physics = entity_mut.get_mut::<Physics>().unwrap();
+                if !should_apply_entity_update(
+                    &mut commands,
+                    &mut world_holder.partial.write(),
+                    entity,
+                    entity_update_query,
+                ) {
+                    return;
+                }
+                let is_local_entity = local_entity.is_some();
 
-                        physics.vec_delta_codec.set_base(new_position);
+                physics.vec_delta_codec.set_base(new_position);
 
-                        if is_local_entity {
-                            debug!("Ignoring entity position sync packet for local player");
-                            return;
-                        }
+                if is_local_entity {
+                    debug!("Ignoring entity position sync packet for local player");
+                    return;
+                }
 
-                        physics.set_on_ground(new_on_ground);
+                physics.set_on_ground(new_on_ground);
 
-                        let mut position = entity_mut.get_mut::<Position>().unwrap();
-                        **position = new_position;
+                if **position != new_position {
+                    **position = new_position;
+                }
 
-                        let mut look_direction = entity_mut.get_mut::<LookDirection>().unwrap();
-                        *look_direction = new_look_direction;
-                    },
-                ));
+                if *look_direction != new_look_direction {
+                    *look_direction = new_look_direction;
+                }
             },
         );
     }

azalea-client/src/plugins/packet/mod.rs

@@ -11,6 +11,7 @@ use crate::chat::ChatReceivedEvent;
 pub mod config;
 pub mod game;
 pub mod login;
+pub mod relative_updates;
 
 pub struct PacketPlugin;
 
@@ -30,23 +31,27 @@ pub fn death_event_on_0_health(
 
 impl Plugin for PacketPlugin {
     fn build(&self, app: &mut App) {
-        app.add_observer(game::handle_outgoing_packets_observer)
-            .add_observer(config::handle_outgoing_packets_observer)
-            .add_observer(login::handle_outgoing_packets_observer)
-            .add_systems(Update, death_event_on_0_health)
-            .add_message::<game::ReceiveGamePacketEvent>()
-            .add_message::<config::ReceiveConfigPacketEvent>()
-            .add_message::<login::ReceiveLoginPacketEvent>()
-            //
-            .add_message::<game::AddPlayerEvent>()
-            .add_message::<game::RemovePlayerEvent>()
-            .add_message::<game::UpdatePlayerEvent>()
-            .add_message::<ChatReceivedEvent>()
-            .add_message::<game::DeathEvent>()
-            .add_message::<game::KeepAliveEvent>()
-            .add_message::<game::ResourcePackEvent>()
-            .add_message::<game::WorldLoadedEvent>()
-            .add_message::<login::ReceiveCustomQueryEvent>();
+        app.add_systems(
+            Update,
+            relative_updates::debug_detect_updates_received_on_local_entities,
+        )
+        .add_observer(game::handle_outgoing_packets_observer)
+        .add_observer(config::handle_outgoing_packets_observer)
+        .add_observer(login::handle_outgoing_packets_observer)
+        .add_systems(Update, death_event_on_0_health)
+        .add_message::<game::ReceiveGamePacketEvent>()
+        .add_message::<config::ReceiveConfigPacketEvent>()
+        .add_message::<login::ReceiveLoginPacketEvent>()
+        //
+        .add_message::<game::AddPlayerEvent>()
+        .add_message::<game::RemovePlayerEvent>()
+        .add_message::<game::UpdatePlayerEvent>()
+        .add_message::<ChatReceivedEvent>()
+        .add_message::<game::DeathEvent>()
+        .add_message::<game::KeepAliveEvent>()
+        .add_message::<game::ResourcePackEvent>()
+        .add_message::<game::WorldLoadedEvent>()
+        .add_message::<login::ReceiveCustomQueryEvent>();
     }
 }
 
@@ -70,12 +75,21 @@ macro_rules! __declare_packet_handlers {
 
 pub(crate) use __declare_packet_handlers as declare_packet_handlers;
 
+#[derive(Resource)]
+struct CachedSystemState<T: SystemParam + 'static>(SystemState<T>);
+
 pub(crate) fn as_system<T>(ecs: &mut World, f: impl FnOnce(T::Item<'_, '_>))
 where
     T: SystemParam + 'static,
 {
-    let mut system_state = SystemState::<T>::new(ecs);
+    // creating a new SystemState is expensive, so we save them as a Resource in the
+    // ecs
+    let mut system_state = match ecs.remove_resource::<CachedSystemState<T>>() {
+        Some(s) => s.0,
+        None => SystemState::<T>::new(ecs),
+    };
     let values = system_state.get_mut(ecs);
     f(values);
     system_state.apply(ecs);
+    ecs.insert_resource(CachedSystemState(system_state));
 }