sea-orm/src/database/stream/transaction.rs
2021-10-11 12:11:40 +08:00

94 lines
3.4 KiB
Rust

use std::{ops::DerefMut, pin::Pin, task::Poll};
use futures::Stream;
#[cfg(feature = "sqlx-dep")]
use futures::TryStreamExt;
#[cfg(feature = "sqlx-dep")]
use sqlx::Executor;
use futures::lock::MutexGuard;
use crate::{DbErr, InnerConnection, QueryResult, Statement};
#[ouroboros::self_referencing]
/// `TransactionStream` cannot be used in a `transaction` closure as it does not impl `Send`.
/// It seems to be a Rust limitation right now, and solution to work around this deemed to be extremely hard.
pub struct TransactionStream<'a> {
stmt: Statement,
conn: MutexGuard<'a, InnerConnection>,
#[borrows(mut conn, stmt)]
#[not_covariant]
stream: Pin<Box<dyn Stream<Item = Result<QueryResult, DbErr>> + 'this>>,
}
impl<'a> std::fmt::Debug for TransactionStream<'a> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "TransactionStream")
}
}
impl<'a> TransactionStream<'a> {
pub(crate) async fn build(
conn: MutexGuard<'a, InnerConnection>,
stmt: Statement,
) -> TransactionStream<'a> {
TransactionStreamAsyncBuilder {
stmt,
conn,
stream_builder: |conn, stmt| {
Box::pin(async move {
match conn.deref_mut() {
#[cfg(feature = "sqlx-mysql")]
InnerConnection::MySql(c) => {
let query = crate::driver::sqlx_mysql::sqlx_query(stmt);
Box::pin(
c.fetch(query)
.map_ok(Into::into)
.map_err(crate::sqlx_error_to_query_err),
)
as Pin<Box<dyn Stream<Item = Result<QueryResult, DbErr>>>>
}
#[cfg(feature = "sqlx-postgres")]
InnerConnection::Postgres(c) => {
let query = crate::driver::sqlx_postgres::sqlx_query(stmt);
Box::pin(
c.fetch(query)
.map_ok(Into::into)
.map_err(crate::sqlx_error_to_query_err),
)
as Pin<Box<dyn Stream<Item = Result<QueryResult, DbErr>>>>
}
#[cfg(feature = "sqlx-sqlite")]
InnerConnection::Sqlite(c) => {
let query = crate::driver::sqlx_sqlite::sqlx_query(stmt);
Box::pin(
c.fetch(query)
.map_ok(Into::into)
.map_err(crate::sqlx_error_to_query_err),
)
as Pin<Box<dyn Stream<Item = Result<QueryResult, DbErr>>>>
}
#[cfg(feature = "mock")]
InnerConnection::Mock(c) => c.fetch(stmt),
}
})
},
}
.build()
.await
}
}
impl<'a> Stream for TransactionStream<'a> {
type Item = Result<QueryResult, DbErr>;
fn poll_next(
self: Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> Poll<Option<Self::Item>> {
let this = self.get_mut();
this.with_stream_mut(|stream| stream.as_mut().poll_next(cx))
}
}