Experiments in applying Entity-Component-System patterns to durable data storage APIs.
moritz.vongoewels.de
Compare changes
Choose any two refs to compare.
+5
src/change_tracking_disable.sql
+5
src/change_tracking_disable.sql
+40
src/change_tracking_enable.sql
+40
src/change_tracking_enable.sql
···
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-- Runs when a component is attached
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create trigger if not exists components_changes_attach_trigger
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after insert
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on components for each row
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begin
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insert into changes (entity, component, change)
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select new.entity, new.component, 'create'
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where not exists (
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select true from components
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where entity = new.entity
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and component != new.component
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);
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insert into changes (entity, component, change)
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select new.entity, new.component, 'attach';
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end;
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-- Runs when a component is changed
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create trigger if not exists components_changes_update_trigger
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after update
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on components for each row
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begin
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insert into changes (entity, component, change)
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values (new.entity, new.component, 'attach');
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end;
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-- Runs when a component is detached
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create trigger if not exists components_changes_detach_trigger
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after delete
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on components for each row
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begin
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insert into changes (entity, component, change)
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values (old.entity, old.component, 'detach');
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insert into changes (entity, component, change)
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select old.entity, old.component, 'destroy'
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where not exists (
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select true from components where entity = old.entity
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);
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end;
+1
-1
src/entity.rs
+1
-1
src/entity.rs
+209
-8
src/lib.rs
+209
-8
src/lib.rs
···
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pub mod component;
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-
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pub use component::{Component, ComponentRead, ComponentWrite};
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pub mod entity;
···
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pub use resource::*;
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pub mod system;
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use ::rusqlite::{params, OptionalExtension};
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pub use system::*;
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use std::path::Path;
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···
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}
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}
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impl Ecs {
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pub fn enable_change_tracking(&mut self) -> Result<(), Error> {
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self.conn
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.execute_batch(include_str!("change_tracking_enable.sql"))?;
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Ok(())
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}
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-
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-
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pub fn disable_change_tracking(&mut self) -> Result<(), Error> {
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self.conn
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.execute_batch(include_str!("change_tracking_disable.sql"))?;
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Ok(())
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}
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}
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···
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}
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}
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-
pub mod rusqlite {
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-
pub use rusqlite::*;
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#[derive(Debug, PartialEq, Eq)]
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pub enum Change {
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Create { entity: EntityId },
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Attach { entity: EntityId, component: String },
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Detach { entity: EntityId, component: String },
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Destroy { entity: EntityId },
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}
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impl Ecs {
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pub fn latest_change_id(&self) -> Result<Option<i64>, Error> {
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let seq: Option<i64> = self.conn.query_row_and_then(
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"select max(sequence) from changes",
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params![],
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|row| row.get(0),
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)?;
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Ok(seq)
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}
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pub fn clear_changes_up_to(&self, up_to: i64) -> Result<(), Error> {
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self.conn
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.execute("delete from changes where sequence < ?1", params![up_to])?;
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Ok(())
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}
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pub fn changes(&self) -> Result<Vec<Change>, Error> {
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let mut stmt = self
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.conn
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.prepare_cached("select * from changes order by sequence asc")?;
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+
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let changes = stmt
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.query_map(params![], |row| {
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let entity = row.get("entity")?;
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let change: String = row.get("change")?;
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+
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match change.as_str() {
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"create" => Ok(Change::Create { entity }),
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"attach" => {
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let component = row.get("component")?;
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Ok(Change::Attach { entity, component })
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}
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"detach" => {
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let component = row.get("component")?;
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Ok(Change::Detach { entity, component })
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}
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"destroy" => Ok(Change::Destroy { entity }),
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other => {
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panic!("Invalid 'changes.change' {other:?}");
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}
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}
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})?
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.collect::<Result<_, _>>()?;
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Ok(changes)
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}
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pub fn clear_changes(&self) -> Result<(), Error> {
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self.conn.execute("delete from changes", params![])?;
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Ok(())
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}
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}
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pub mod rusqlite {
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pub use rusqlite::*;
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}
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···
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impl sea_query::Iden for Components {
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fn unquoted(&self, s: &mut dyn std::fmt::Write) {
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let v = match self {
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Self::Table => "components",
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Self::Entity => "entity",
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Self::Component => "component",
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Self::Data => "data",
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};
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write!(s, "{v}").unwrap()
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}
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}
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#[allow(unused)]
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pub enum Changes {
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Table,
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Sequence,
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Entity,
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Component,
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Change,
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}
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-
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impl sea_query::Iden for Changes {
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fn unquoted(&self, s: &mut dyn std::fmt::Write) {
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let v = match self {
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Self::Table => "changes",
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Self::Sequence => "sequence",
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Self::Entity => "entity",
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Self::Component => "component",
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Self::Change => "change",
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};
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write!(s, "{v}").unwrap()
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}
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#[cfg(test)]
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mod tests {
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// #[derive(Component)] derives `impl ecsdb::Component for ...`
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use crate::{self as ecsdb, Ecs};
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use crate::{self as ecsdb, Change, Ecs};
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use crate::{BelongsTo, Component};
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use anyhow::anyhow;
···
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Ok(())
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}
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#[test]
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fn change_tracking_enable_disable() -> Result<(), anyhow::Error> {
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let mut ecs = super::Ecs::open_in_memory()?;
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ecs.enable_change_tracking()?;
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assert_eq!(ecs.changes()?, vec![]);
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ecs.new_entity().attach(A);
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assert_eq!(ecs.changes()?.len(), 2);
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ecs.disable_change_tracking()?;
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ecs.clear_changes()?;
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ecs.new_entity().attach(A);
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assert!(ecs.changes()?.is_empty());
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Ok(())
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}
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#[test]
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fn change_tracking() -> Result<(), anyhow::Error> {
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let mut ecs = super::Ecs::open_in_memory()?;
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ecs.enable_change_tracking()?;
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let mut changes = vec![];
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assert_eq!(ecs.changes()?, vec![]);
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let entity = ecs.new_entity().attach(A);
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changes.extend([
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Change::Create {
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entity: entity.id(),
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},
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Change::Attach {
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entity: entity.id(),
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component: <A as Component>::component_name().to_owned(),
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},
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]);
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assert_eq!(ecs.changes()?, changes);
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entity.attach(B);
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changes.push(Change::Attach {
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entity: entity.id(),
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component: <B as Component>::component_name().to_owned(),
719
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});
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assert_eq!(ecs.changes()?, changes);
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723
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entity.detach::<B>();
724
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changes.push(Change::Detach {
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entity: entity.id(),
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component: <B as Component>::component_name().to_owned(),
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});
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assert_eq!(ecs.changes()?, changes);
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731
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entity.detach::<A>();
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changes.extend([
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Change::Detach {
734
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entity: entity.id(),
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component: <A as Component>::component_name().to_owned(),
736
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},
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Change::Destroy {
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entity: entity.id(),
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},
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]);
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assert_eq!(ecs.changes()?, changes);
743
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ecs.clear_changes()?;
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assert!(ecs.changes()?.is_empty());
746
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747
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Ok(())
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}
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#[test]
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fn changed_system_param() -> Result<(), anyhow::Error> {
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#[derive(Debug, Deserialize, Serialize, Component)]
753
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struct Seen;
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+
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let mut ecs = super::Ecs::open_in_memory()?;
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ecs.enable_change_tracking()?;
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+
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fn system(query: Query<Attached<B>>) {
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assert_eq!(query.iter().map(|e| e.id()).collect::<Vec<_>>(), vec![200]);
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+
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query.iter().for_each(|e| {
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e.attach(Seen);
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});
764
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}
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ecs.register(system);
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ecs.entity(100).attach(A);
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ecs.entity(200).attach(B);
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ecs.tick();
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assert!(ecs.entity(200).has::<Seen>());
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Ok(())
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}
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}
+7
src/schema.sql
+7
src/schema.sql
···
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end;
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create table if not exists changes (
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sequence integer primary key autoincrement,
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entity integer not null,
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component text,
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change text not null
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);
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create table if not exists resources (
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name text not null unique,
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data blob,
+214
-1
src/system.rs
+214
-1
src/system.rs
···
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use serde::{Deserialize, Serialize};
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use tracing::{debug, error};
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use crate::{self as ecsdb, query, Component, Ecs, Entity, EntityId};
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use crate::{self as ecsdb, query, Component, Ecs, Entity, Error};
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use core::marker::PhantomData;
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use std::borrow::Cow;
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196
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impl Ecs {
197
+
pub fn tick(&self) {
198
+
let latest_change = self.latest_change_id().unwrap();
199
+
200
+
for system in &self.systems {
201
+
let _span = tracing::info_span!("system", name = system.name().as_ref()).entered();
202
+
let started = std::time::Instant::now();
203
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204
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205
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206
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207
+
208
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209
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210
+
211
+
error!(?e);
212
+
}
213
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214
+
if let Some(latest_change) = latest_change {
215
+
self.clear_changes_up_to(latest_change).unwrap();
216
+
}
217
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218
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entity.attach(LastRun(chrono::Utc::now()));
219
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220
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debug!(elapsed_ms = started.elapsed().as_millis(), "Finished",);
+56
-1
src/query.rs
+56
-1
src/query.rs
···
1
-
use crate::EntityId;
1
+
use crate::{sql::Changes, EntityId};
2
2
3
3
use super::{sql::Components, Component};
4
4
use std::{any, marker::PhantomData};
···
167
167
}
168
168
169
169
pub struct Without<C>(PhantomData<C>);
170
+
170
171
impl<C: Component> Filter for Without<C> {
171
172
fn sql_query() -> sea_query::SelectStatement {
172
173
use sea_query::*;
···
178
179
}
179
180
}
180
181
182
+
pub struct Attached<C>(PhantomData<C>);
183
+
184
+
impl<C: Component> Filter for Attached<C> {
185
+
fn sql_query() -> sea_query::SelectStatement {
186
+
use sea_query::*;
187
+
Query::select()
188
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.column(Changes::Entity)
189
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.from(Changes::Table)
190
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.and_where(Expr::col(Changes::Component).eq(C::component_name()))
191
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.and_where(Expr::col(Changes::Change).eq("attach"))
192
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.take()
193
+
}
194
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}
195
+
196
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pub struct Detached<C>(PhantomData<C>);
197
+
198
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impl<C: Component> Filter for Detached<C> {
199
+
fn sql_query() -> sea_query::SelectStatement {
200
+
use sea_query::*;
201
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Query::select()
202
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.column(Changes::Entity)
203
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.from(Changes::Table)
204
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.and_where(Expr::col(Changes::Component).eq(C::component_name()))
205
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.and_where(Expr::col(Changes::Change).eq("detach"))
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.take()
207
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}
208
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}
209
+
210
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pub struct Created;
211
+
212
+
impl Filter for Created {
213
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fn sql_query() -> sea_query::SelectStatement {
214
+
use sea_query::*;
215
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Query::select()
216
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.column(Changes::Entity)
217
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.from(Changes::Table)
218
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.and_where(Expr::col(Changes::Change).eq("create"))
219
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.take()
220
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}
221
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}
222
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223
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pub struct Destroyed;
224
+
225
+
impl Filter for Destroyed {
226
+
fn sql_query() -> sea_query::SelectStatement {
227
+
use sea_query::*;
228
+
Query::select()
229
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.column(Changes::Entity)
230
+
.from(Changes::Table)
231
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.and_where(Expr::col(Changes::Change).eq("destroy"))
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.take()
233
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}
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}
235
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pub struct Or<T>(PhantomData<T>);
182
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238
macro_rules! filter_tuple_impl {