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use std::future::{Future, IntoFuture};
use std::marker::PhantomData;
use std::pin::Pin;
use std::task::{Context, Poll};
use std::time::Instant;
use tracing::Instrument;
use crate::error::ErrorKind;
use crate::query::Query;
use crate::{Error, Sql};
impl<'a, Cols, T> IntoFuture for Sql<'a, Cols, T>
where
T: Query<Cols> + Send + Sync + 'a,
Cols: Send + Sync + 'a,
{
type Output = Result<T, Error>;
type IntoFuture = SqlFuture<'a, T>;
fn into_future(self) -> Self::IntoFuture {
SqlFuture::new(self)
}
}
/// A future for executing an sql query.
pub struct SqlFuture<'a, T> {
future: Pin<Box<dyn Future<Output = Result<T, Error>> + Send + 'a>>,
marker: PhantomData<&'a ()>,
}
impl<'a, T> SqlFuture<'a, T> {
pub(crate) fn new<Cols>(sql: Sql<'a, Cols, T>) -> Self
where
T: Query<Cols> + Send + Sync + 'a,
Cols: Send + Sync + 'a,
{
let span =
tracing::debug_span!("sql query", query = sql.query, parameters = ?sql.parameters);
let start = Instant::now();
SqlFuture {
future: Box::pin(
// Note: changes here must be applied to `with_connection` below too!
async move {
let mut i = 1;
loop {
let conn = super::connect().await?;
match T::query(&sql, &conn).await {
Ok(r) => {
let elapsed = start.elapsed();
tracing::trace!(?elapsed, "sql query finished");
return Ok(r);
}
Err(Error {
kind: ErrorKind::Postgres(err),
..
}) if err.is_closed() && i <= 5 => {
// retry pool size + 1 times if connection is closed (might have
// received a closed one from the connection pool)
i += 1;
tracing::trace!("retry due to connection closed error");
continue;
}
Err(err) => {
return Err(err);
}
}
}
}
.instrument(span),
),
marker: PhantomData,
}
}
pub(crate) fn with_connection<Cols>(
sql: Sql<'a, Cols, T>,
conn: impl super::Connection + 'a,
) -> Self
where
T: Query<Cols> + Send + Sync + 'a,
Cols: Send + Sync + 'a,
{
let span =
tracing::debug_span!("sql query", query = sql.query, parameters = ?sql.parameters);
let start = Instant::now();
SqlFuture {
future: Box::pin(
// Note: changes here must be applied to `bew` above too!
async move {
let mut i = 1;
loop {
match T::query(&sql, &conn).await {
Ok(r) => {
let elapsed = start.elapsed();
tracing::trace!(?elapsed, "sql query finished");
return Ok(r);
}
Err(Error {
kind: ErrorKind::Postgres(err),
..
}) if err.is_closed() && i <= 5 => {
// retry pool size + 1 times if connection is closed (might have
// received a closed one from the connection pool)
i += 1;
tracing::trace!("retry due to connection closed error");
continue;
}
Err(err) => {
return Err(err);
}
}
}
}
.instrument(span),
),
marker: PhantomData,
}
}
}
impl<'a, T> Future for SqlFuture<'a, T> {
type Output = Result<T, Error>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
self.future.as_mut().poll(cx)
}
}