Cutout unnecessary Resource syncing machinery and Tracker trait

client/src/lib.rs

@@ -79,9 +79,9 @@ impl Client {
         // Wait for initial sync
         let (state, entity, server_info, world_map) = match postbox.next_message() {
             Some(ServerMsg::InitialSync {
-                ecs_state,
+                entity_package,
-                entity_uid,
                 server_info,
+                time_of_day,
                 // world_map: /*(map_size, world_map)*/map_size,
             }) => {
                 // TODO: Voxygen should display this.
@@ -95,12 +95,10 @@ impl Client {
                     );
                 }
 
+                // Initialize `State`
                 let mut state = State::default();
-                state.ecs_mut().apply_state_package(ecs_state);
+                let entity = state.ecs_mut().apply_entity_package(entity_package);
-                let entity = state
+                *state.ecs_mut().write_resource() = time_of_day;
-                    .ecs()
-                    .entity_from_uid(entity_uid)
-                    .ok_or(Error::ServerWentMad)?;
 
                 // assert_eq!(world_map.len(), map_size.x * map_size.y);
                 let map_size = Vec2::new(1024, 1024);
@@ -539,7 +537,7 @@ impl Client {
 
                         self.last_ping_delta = Instant::now()
                             .duration_since(self.last_server_ping)
-                            .as_secs_f64()
+                            .as_secs_f64();
                     }
                     ServerMsg::ChatMsg { chat_type, message } => {
                         frontend_events.push(Event::Chat { chat_type, message })
@@ -551,15 +549,14 @@ impl Client {
                             return Err(Error::Other("Failed to find entity from uid.".to_owned()));
                         }
                     }
-                    ServerMsg::EcsSync(sync_package) => {
+                    ServerMsg::TimeOfDay(time_of_day) => {
-                        self.state.ecs_mut().apply_sync_package(sync_package)
+                        *self.state.ecs_mut().write_resource() = time_of_day;
+                    }
+                    ServerMsg::EcsSync(sync_package) => {
+                        self.state.ecs_mut().apply_sync_package(sync_package);
                     }
-                    ServerMsg::EcsResSync(res_sync_package) => self
-                        .state
-                        .ecs_mut()
-                        .apply_res_sync_package(res_sync_package),
                     ServerMsg::CreateEntity(entity_package) => {
-                        self.state.ecs_mut().apply_entity_package(entity_package)
+                        self.state.ecs_mut().apply_entity_package(entity_package);
                     }
                     ServerMsg::DeleteEntity(entity) => {
                         if self

common/src/msg/ecs_packet.rs

@@ -1,29 +1,8 @@
-use crate::{comp, state, sync};
+use crate::{comp, sync};
 use serde_derive::{Deserialize, Serialize};
 use std::marker::PhantomData;
 use sum_type::sum_type;
 
-// TODO: remove me
-#[derive(Clone, Debug, Serialize, Deserialize)]
-pub enum MustHaveMoreThanOneVariant {}
-
-// Automatically derive From<T> for EcsResPacket
-// for each variant EcsResPacket::T(T).
-sum_type! {
-    #[derive(Clone, Debug, Serialize, Deserialize)]
-    pub enum EcsResPacket {
-        MustHaveMoreThanOneVariant(MustHaveMoreThanOneVariant),
-        TimeOfDay(state::TimeOfDay),
-    }
-}
-impl sync::ResPacket for EcsResPacket {
-    fn apply(self, world: &specs::World) {
-        match self {
-            EcsResPacket::MustHaveMoreThanOneVariant(_) => unimplemented!(),
-            EcsResPacket::TimeOfDay(time_of_day) => sync::handle_res_update(time_of_day, world),
-        }
-    }
-}
 // Automatically derive From<T> for EcsCompPacket
 // for each variant EcsCompPacket::T(T.)
 sum_type! {

common/src/msg/mod.rs

@@ -4,7 +4,7 @@ pub mod server;
 
 // Reexports
 pub use self::client::ClientMsg;
-pub use self::ecs_packet::{EcsCompPacket, EcsResPacket};
+pub use self::ecs_packet::EcsCompPacket;
 pub use self::server::{RequestStateError, ServerError, ServerInfo, ServerMsg};
 
 #[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]

common/src/msg/server.rs

@@ -1,6 +1,6 @@
-use super::{ClientState, EcsCompPacket, EcsResPacket};
+use super::{ClientState, EcsCompPacket};
 use crate::{
-    comp, sync,
+    comp, state, sync,
     terrain::{Block, TerrainChunk},
     ChatType,
 };
@@ -26,9 +26,9 @@ pub struct ServerInfo {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub enum ServerMsg {
     InitialSync {
-        ecs_state: sync::StatePackage<EcsCompPacket, EcsResPacket>,
+        entity_package: sync::EntityPackage<EcsCompPacket>,
-        entity_uid: u64,
         server_info: ServerInfo,
+        time_of_day: state::TimeOfDay,
         // world_map: Vec2<usize>, /*, Vec<u32>)*/
     },
     StateAnswer(Result<ClientState, (RequestStateError, ClientState)>),
@@ -40,8 +40,8 @@ pub enum ServerMsg {
         message: String,
     },
     SetPlayerEntity(u64),
+    TimeOfDay(state::TimeOfDay),
     EcsSync(sync::SyncPackage<EcsCompPacket>),
-    EcsResSync(sync::ResSyncPackage<EcsResPacket>),
     CreateEntity(sync::EntityPackage<EcsCompPacket>),
     DeleteEntity(u64),
     EntityPos {

common/src/state.rs

@@ -23,7 +23,7 @@ use vek::*;
 const DAY_CYCLE_FACTOR: f64 = 24.0 * 2.0;
 
 /// A resource that stores the time of day.
-#[derive(Clone, Debug, Serialize, Deserialize)]
+#[derive(Copy, Clone, Debug, Serialize, Deserialize)]
 pub struct TimeOfDay(pub f64);
 
 /// A resource that stores the tick (i.e: physics) time.

common/src/sync/mod.rs

@@ -6,9 +6,9 @@ mod uid;
 
 // Reexports
 pub use packet::{
-    handle_insert, handle_modify, handle_remove, handle_res_update, CompPacket, EntityPackage,
+    handle_insert, handle_modify, handle_remove, CompPacket, EntityPackage, StatePackage,
-    ResPacket, ResSyncPackage, StatePackage, SyncPackage,
+    SyncPackage,
 };
 pub use sync_ext::WorldSyncExt;
-pub use track::{Tracker, UpdateTracker};
+pub use track::UpdateTracker;
 pub use uid::{Uid, UidAllocator};

common/src/sync/packet.rs

@@ -1,10 +1,7 @@
-use super::{
+use super::{track::UpdateTracker, uid::Uid};
-    track::{Tracker, UpdateTracker},
-    uid::Uid,
-};
 use log::error;
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
-use specs::{shred::Resource, Component, Entity, Join, ReadStorage, World, WorldExt};
+use specs::{Component, Entity, Join, ReadStorage, World, WorldExt};
 use std::{
     convert::{TryFrom, TryInto},
     fmt::Debug,
@@ -19,10 +16,6 @@ pub trait CompPacket: Clone + Debug + Send + 'static {
     fn apply_remove(phantom: Self::Phantom, entity: Entity, world: &World);
 }
 
-pub trait ResPacket: Clone + Debug + Send + 'static {
-    fn apply(self, world: &World);
-}
-
 /// Useful for implementing CompPacket trait
 pub fn handle_insert<C: Component>(comp: C, entity: Entity, world: &World) {
     if let Err(err) = world.write_storage::<C>().insert(entity, comp) {
@@ -40,10 +33,6 @@ pub fn handle_modify<C: Component>(comp: C, entity: Entity, world: &World) {
 pub fn handle_remove<C: Component>(entity: Entity, world: &World) {
     let _ = world.write_storage::<C>().remove(entity);
 }
-/// Useful for implementing ResPacket trait
-pub fn handle_res_update<R: Resource>(res: R, world: &World) {
-    *world.write_resource::<R>() = res;
-}
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize)]
 pub enum CompUpdateKind<P: CompPacket> {
@@ -53,24 +42,25 @@ pub enum CompUpdateKind<P: CompPacket> {
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
-pub struct EntityPackage<P: CompPacket>(pub u64, pub Vec<P>);
+pub struct EntityPackage<P: CompPacket> {
-
+    pub uid: u64,
-#[derive(Clone, Debug, Serialize, Deserialize)]
+    pub comps: Vec<P>,
-pub struct StatePackage<P: CompPacket, R: ResPacket> {
-    pub entities: Vec<EntityPackage<P>>,
-    pub resources: Vec<R>,
 }
 
-impl<P: CompPacket, R: ResPacket> Default for StatePackage<P, R> {
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct StatePackage<P: CompPacket> {
+    pub entities: Vec<EntityPackage<P>>,
+}
+
+impl<P: CompPacket> Default for StatePackage<P> {
     fn default() -> Self {
         Self {
             entities: Vec::new(),
-            resources: Vec::new(),
         }
     }
 }
 
-impl<P: CompPacket, R: ResPacket> StatePackage<P, R> {
+impl<P: CompPacket> StatePackage<P> {
     pub fn new() -> Self {
         Self::default()
     }
@@ -85,13 +75,6 @@ impl<P: CompPacket, R: ResPacket> StatePackage<P, R> {
         self.entities.push(entry);
         self
     }
-    pub fn with_res<C: Resource + Clone + Send + Sync>(mut self, res: &C) -> Self
-    where
-        R: From<C>,
-    {
-        self.resources.push(R::from(res.clone()));
-        self
-    }
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -122,7 +105,7 @@ impl<P: CompPacket> SyncPackage<P> {
     pub fn with_component<'a, C: Component + Clone + Send + Sync>(
         mut self,
         uids: &ReadStorage<'a, Uid>,
-        tracker: &impl Tracker<C, P>,
+        tracker: &UpdateTracker<C>,
         storage: &ReadStorage<'a, C>,
         filter: impl Join + Copy,
     ) -> Self
@@ -137,22 +120,3 @@ impl<P: CompPacket> SyncPackage<P> {
         self
     }
 }
-
-#[derive(Clone, Debug, Serialize, Deserialize)]
-pub struct ResSyncPackage<R: ResPacket> {
-    pub resources: Vec<R>,
-}
-impl<R: ResPacket> ResSyncPackage<R> {
-    pub fn new() -> Self {
-        Self {
-            resources: Vec::new(),
-        }
-    }
-    pub fn with_res<C: Resource + Clone + Send + Sync>(mut self, res: &C) -> Self
-    where
-        R: From<C>,
-    {
-        self.resources.push(R::from(res.clone()));
-        self
-    }
-}

common/src/sync/sync_ext.rs

@@ -1,8 +1,5 @@
 use super::{
-    packet::{
+    packet::{CompPacket, CompUpdateKind, EntityPackage, StatePackage, SyncPackage},
-        CompPacket, CompUpdateKind, EntityPackage, ResPacket, ResSyncPackage, StatePackage,
-        SyncPackage,
-    },
     track::UpdateTracker,
     uid::{Uid, UidAllocator},
 };
@@ -25,13 +22,12 @@ pub trait WorldSyncExt {
     fn delete_entity_and_clear_from_uid_allocator(&mut self, uid: u64);
     fn uid_from_entity(&self, entity: specs::Entity) -> Option<Uid>;
     fn entity_from_uid(&self, uid: u64) -> Option<specs::Entity>;
-    fn apply_entity_package<P: CompPacket>(&mut self, entity_package: EntityPackage<P>);
+    fn apply_entity_package<P: CompPacket>(
-    fn apply_state_package<P: CompPacket, R: ResPacket>(
         &mut self,
-        state_package: StatePackage<P, R>,
+        entity_package: EntityPackage<P>,
-    );
+    ) -> specs::Entity;
+    fn apply_state_package<P: CompPacket>(&mut self, state_package: StatePackage<P>);
     fn apply_sync_package<P: CompPacket>(&mut self, package: SyncPackage<P>);
-    fn apply_res_sync_package<R: ResPacket>(&mut self, package: ResSyncPackage<R>);
 }
 
 impl WorldSyncExt for specs::World {
@@ -71,13 +67,18 @@ impl WorldSyncExt for specs::World {
             .retrieve_entity_internal(uid)
     }
 
-    fn apply_entity_package<P: CompPacket>(&mut self, entity_package: EntityPackage<P>) {
+    fn apply_entity_package<P: CompPacket>(
-        let EntityPackage(entity_uid, packets) = entity_package;
+        &mut self,
+        entity_package: EntityPackage<P>,
+    ) -> specs::Entity {
+        let EntityPackage { uid, comps } = entity_package;
 
-        let entity = create_entity_with_uid(self, entity_uid);
+        let entity = create_entity_with_uid(self, uid);
-        for packet in packets {
+        for packet in comps {
             packet.apply_insert(entity, self)
         }
+
+        entity
     }
 
     fn delete_entity_and_clear_from_uid_allocator(&mut self, uid: u64) {
@@ -90,25 +91,15 @@ impl WorldSyncExt for specs::World {
         }
     }
 
-    fn apply_state_package<P: CompPacket, R: ResPacket>(
+    fn apply_state_package<P: CompPacket>(&mut self, state_package: StatePackage<P>) {
-        &mut self,
+        let StatePackage { entities } = state_package;
-        state_package: StatePackage<P, R>,
-    ) {
-        let StatePackage {
-            entities,
-            resources,
-        } = state_package;
-
-        // Apply state package resources
-        for res_packet in resources {
-            res_packet.apply(self);
-        }
 
         // Apply state package entities
         for entity_package in entities {
             self.apply_entity_package(entity_package);
         }
 
+        // TODO: determine if this is needed
         // Initialize entities
         //self.maintain();
     }
@@ -151,12 +142,6 @@ impl WorldSyncExt for specs::World {
             self.delete_entity_and_clear_from_uid_allocator(entity_uid);
         }
     }
-    fn apply_res_sync_package<R: ResPacket>(&mut self, package: ResSyncPackage<R>) {
-        // Update resources
-        for res_packet in package.resources {
-            res_packet.apply(self);
-        }
-    }
 }
 
 // Private utilities

common/src/sync/track.rs

@@ -8,29 +8,6 @@ use std::{
     marker::PhantomData,
 };
 
-pub trait Tracker<C: Component + Clone + Send + Sync, P: CompPacket>: Send + 'static
-where
-    P: From<C>,
-    C: TryFrom<P>,
-    P::Phantom: From<PhantomData<C>>,
-    P::Phantom: TryInto<PhantomData<C>>,
-    C::Storage: specs::storage::Tracked,
-{
-    fn add_packet_for<'a>(
-        &self,
-        storage: &specs::ReadStorage<'a, C>,
-        entity: specs::Entity,
-        packets: &mut Vec<P>,
-    );
-    fn get_updates_for<'a>(
-        &self,
-        uids: &specs::ReadStorage<'a, Uid>,
-        storage: &specs::ReadStorage<'a, C>,
-        filter: impl Join + Copy,
-        buf: &mut Vec<(u64, CompUpdateKind<P>)>,
-    );
-}
-
 pub struct UpdateTracker<C: Component> {
     reader_id: specs::ReaderId<specs::storage::ComponentEvent>,
     inserted: BitSet,
@@ -92,32 +69,39 @@ where
     }
 }
 
-impl<C: Component + Clone + Send + Sync, P: CompPacket> Tracker<C, P> for UpdateTracker<C>
+impl<C: Component + Clone + Send + Sync> UpdateTracker<C> {
-where
+    pub fn add_packet_for<'a, P>(
+        &self,
+        storage: &ReadStorage<'a, C>,
+        entity: Entity,
+        packets: &mut Vec<P>,
+    ) where
+        P: CompPacket,
         P: From<C>,
         C: TryFrom<P>,
         P::Phantom: From<PhantomData<C>>,
         P::Phantom: TryInto<PhantomData<C>>,
         C::Storage: specs::storage::Tracked,
     {
-    fn add_packet_for<'a>(
-        &self,
-        storage: &ReadStorage<'a, C>,
-        entity: Entity,
-        packets: &mut Vec<P>,
-    ) {
         if let Some(comp) = storage.get(entity) {
             packets.push(P::from(comp.clone()));
         }
     }
 
-    fn get_updates_for<'a>(
+    pub fn get_updates_for<'a, P>(
         &self,
         uids: &specs::ReadStorage<'a, Uid>,
         storage: &specs::ReadStorage<'a, C>,
         entity_filter: impl Join + Copy,
         buf: &mut Vec<(u64, CompUpdateKind<P>)>,
-    ) {
+    ) where
+        P: CompPacket,
+        P: From<C>,
+        C: TryFrom<P>,
+        P::Phantom: From<PhantomData<C>>,
+        P::Phantom: TryInto<PhantomData<C>>,
+        C::Storage: specs::storage::Tracked,
+    {
         // Generate inserted updates
         for (uid, comp, _, _) in (uids, storage, &self.inserted, entity_filter).join() {
             buf.push((

server/src/lib.rs

@@ -19,7 +19,7 @@ use crate::{
     chunk_generator::ChunkGenerator,
     client::{Client, RegionSubscription},
     cmd::CHAT_COMMANDS,
-    sys::sentinel::{DeletedEntities, TrackedComps, TrackedResources},
+    sys::sentinel::{DeletedEntities, TrackedComps},
 };
 use common::{
     assets, comp,
@@ -992,7 +992,8 @@ impl Server {
                     .create_entity_synced()
                     .with(client)
                     .build();
-                // Return the state of the current world (all of the components that Sphynx tracks).
+                // Send client all the tracked components currently attached to its entity as well
+                // as synced resources (currently only `TimeOfDay`)
                 log::debug!("Starting initial sync with client.");
                 self.state
                     .ecs()
@@ -1000,15 +1001,11 @@ impl Server {
                     .get_mut(entity)
                     .unwrap()
                     .notify(ServerMsg::InitialSync {
-                        ecs_state: TrackedResources::fetch(&self.state.ecs())
-                            .state_package()
                         // Send client their entity
-                            .with_entity(
+                        entity_package: TrackedComps::fetch(&self.state.ecs())
-                                TrackedComps::fetch(&self.state.ecs())
                             .create_entity_package(entity),
-                            ),
-                        entity_uid: self.state.ecs().uid_from_entity(entity).unwrap().into(), // Can't fail.
                         server_info: self.server_info.clone(),
+                        time_of_day: *self.state.ecs().read_resource(),
                         // world_map: (WORLD_SIZE/*, self.world.sim().get_map()*/),
                     });
                 log::debug!("Done initial sync with client.");

server/src/sys/entity_sync.rs

@@ -1,5 +1,5 @@
 use super::{
-    sentinel::{DeletedEntities, ReadTrackers, TrackedComps, TrackedResources},
+    sentinel::{DeletedEntities, ReadTrackers, TrackedComps},
     SysTimer,
 };
 use crate::{
@@ -10,6 +10,7 @@ use common::{
     comp::{CharacterState, ForceUpdate, Inventory, InventoryUpdate, Last, Ori, Pos, Vel},
     msg::ServerMsg,
     region::{Event as RegionEvent, RegionMap},
+    state::TimeOfDay,
     sync::Uid,
 };
 use specs::{
@@ -22,6 +23,7 @@ impl<'a> System<'a> for Sys {
     type SystemData = (
         Entities<'a>,
         Read<'a, Tick>,
+        ReadExpect<'a, TimeOfDay>,
         ReadExpect<'a, RegionMap>,
         Write<'a, SysTimer<Self>>,
         ReadStorage<'a, Uid>,
@@ -41,7 +43,6 @@ impl<'a> System<'a> for Sys {
         Write<'a, DeletedEntities>,
         TrackedComps<'a>,
         ReadTrackers<'a>,
-        TrackedResources<'a>,
     );
 
     fn run(
@@ -49,6 +50,7 @@ impl<'a> System<'a> for Sys {
         (
             entities,
             tick,
+            time_of_day,
             region_map,
             mut timer,
             uids,
@@ -68,7 +70,6 @@ impl<'a> System<'a> for Sys {
             mut deleted_entities,
             tracked_comps,
             trackers,
-            tracked_resources,
         ): Self::SystemData,
     ) {
         timer.start();
@@ -329,10 +330,10 @@ impl<'a> System<'a> for Sys {
         inventory_updates.clear();
 
         // Sync resources
-        // TODO: doesn't really belong in this system
+        // TODO: doesn't really belong in this system (rename system or create another system?)
-        let res_msg = ServerMsg::EcsResSync(tracked_resources.create_res_sync_package());
+        let tof_msg = ServerMsg::TimeOfDay(*time_of_day);
         for client in (&mut clients).join() {
-            client.notify(res_msg.clone());
+            client.notify(tof_msg.clone());
         }
 
         timer.end();

server/src/sys/sentinel.rs

@@ -4,12 +4,8 @@ use common::{
         Body, CanBuild, Gravity, Item, LightEmitter, Mass, MountState, Mounting, Player, Scale,
         Stats, Sticky,
     },
-    msg::{EcsCompPacket, EcsResPacket},
+    msg::EcsCompPacket,
-    state::TimeOfDay,
+    sync::{EntityPackage, SyncPackage, Uid, UpdateTracker, WorldSyncExt},
-    sync::{
-        CompPacket, EntityPackage, ResSyncPackage, StatePackage, SyncPackage, Uid, UpdateTracker,
-        WorldSyncExt,
-    },
 };
 use hashbrown::HashMap;
 use specs::{
@@ -62,57 +58,48 @@ impl<'a> TrackedComps<'a> {
             .copied()
             .expect("No uid to create an entity package")
             .0;
-        let mut packets = Vec::new();
+        let mut comps = Vec::new();
-        self.body
+        self.body.get(entity).copied().map(|c| comps.push(c.into()));
-            .get(entity)
-            .copied()
-            .map(|c| packets.push(c.into()));
         self.player
             .get(entity)
             .cloned()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
         self.stats
             .get(entity)
             .cloned()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
         self.can_build
             .get(entity)
             .cloned()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
         self.light_emitter
             .get(entity)
             .copied()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
-        self.item
+        self.item.get(entity).cloned().map(|c| comps.push(c.into()));
-            .get(entity)
-            .cloned()
-            .map(|c| packets.push(c.into()));
         self.scale
             .get(entity)
             .copied()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
         self.mounting
             .get(entity)
             .cloned()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
         self.mount_state
             .get(entity)
             .cloned()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
-        self.mass
+        self.mass.get(entity).copied().map(|c| comps.push(c.into()));
-            .get(entity)
-            .copied()
-            .map(|c| packets.push(c.into()));
         self.sticky
             .get(entity)
             .copied()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
         self.gravity
             .get(entity)
             .copied()
-            .map(|c| packets.push(c.into()));
+            .map(|c| comps.push(c.into()));
 
-        EntityPackage(uid, packets)
+        EntityPackage { uid, comps }
     }
 }
 #[derive(SystemData)]
@@ -209,20 +196,6 @@ pub fn register_trackers(world: &mut World) {
     world.register_tracker::<Gravity>();
 }
 
-#[derive(SystemData)]
-pub struct TrackedResources<'a> {
-    time_of_day: ReadExpect<'a, TimeOfDay>,
-}
-impl<'a> TrackedResources<'a> {
-    pub fn create_res_sync_package(&self) -> ResSyncPackage<EcsResPacket> {
-        ResSyncPackage::new().with_res(&*self.time_of_day)
-    }
-    /// Create state package with resources included
-    pub fn state_package<C: CompPacket>(&self) -> StatePackage<C, EcsResPacket> {
-        StatePackage::new().with_res(&*self.time_of_day)
-    }
-}
-
 /// Deleted entities grouped by region
 pub struct DeletedEntities {
     map: HashMap<Vec2<i32>, Vec<u64>>,