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use sqlx::{SqliteConnection, Transaction, sqlite::Sqlite};
use crate::{
clock::DateTime,
event::{Instant, Sequence},
};
pub trait Provider {
fn sequence(&mut self) -> Sequences<'_>;
}
impl Provider for Transaction<'_, Sqlite> {
fn sequence(&mut self) -> Sequences<'_> {
Sequences(self)
}
}
pub struct Sequences<'t>(&'t mut SqliteConnection);
impl Sequences<'_> {
pub async fn next(&mut self, at: &DateTime) -> Result<Instant, sqlx::Error> {
let next = sqlx::query_scalar!(
r#"
update event_sequence
set last_value = last_value + 1
returning last_value as "next_value: Sequence"
"#,
)
.fetch_one(&mut *self.0)
.await?;
Ok(Instant::new(*at, next))
}
pub async fn current(&mut self) -> Result<Sequence, sqlx::Error> {
let next = sqlx::query_scalar!(
r#"
select last_value as "last_value: Sequence"
from event_sequence
"#,
)
.fetch_one(&mut *self.0)
.await?;
Ok(next)
}
}
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