I'm experimenting with Rocket, Rust and SQLx and I'd like to test what happens when two parallel transactions try to insert a duplicated record on my table.
My insert fn contains nothing special and it works fine:
async fn insert_credentials<'ex, EX>(&self, executor: EX, credentials: &Credentials) -> Result<u64, Errors>
where
EX: 'ex + Executor<'ex, Database = Postgres>,
{
sqlx::query!(
r#"INSERT INTO credentials (username, password)
VALUES ($1, crypt($2, gen_salt('bf')))"#,
credentials.username,
credentials.password,
)
.execute(executor)
.await
.map(|result| result.rows_affected())
.map_err(|err| err.into())
}
My test, though, hangs indefinitely since it waits for a commit that never happens:
#[async_std::test]
async fn it_should_reject_duplicated_username_in_parallel() {
let repo = new_repo();
let db: Pool<Postgres> = connect().await;
let credentials = new_random_credentials();
println!("TX1 begins");
let mut tx1 = db.begin().await.unwrap();
let rows_affected = repo.insert_credentials(&mut tx1, &credentials).await.unwrap();
assert_eq!(rows_affected, 1);
println!("TX2 begins");
let mut tx2 = db.begin().await.unwrap();
println!("It hangs on the next line");
let rows_affected = repo.insert_credentials(&mut tx2, &credentials).await.unwrap();
assert_eq!(rows_affected, 1);
println!("It never reaches this line");
tx1.commit().await.unwrap();
tx2.commit().await.unwrap();
}
How do I create and execute those TXs in parallel, such that the assertions pass but the test fails when trying to commit the second TX?
For reference, this is my Cargo.toml
[package]
name = "auth"
version = "0.1.0"
edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
async-trait = "0.1.52"
serde = "1.0.136"
thiserror = "1.0.30"
# TODO https://github.com/SergioBenitez/Rocket/issues/1893#issuecomment-1002393878
rocket = { git = "https://github.com/SergioBenitez/Rocket", features = ["json"] }
[dependencies.redis]
version = "0.21.5"
features = ["tokio-comp"]
[dependencies.sqlx]
version = "0.5.11"
features = ["macros", "runtime-tokio-rustls", "postgres"]
[dependencies.uuid]
version = "1.0.0-alpha.1"
features = ["v4", "fast-rng", "macro-diagnostics"]
## DEV ##
[dev-dependencies]
mockall = "0.11.0"
[dev-dependencies.async-std]
version = "1.11.0"
features = ["attributes", "tokio1"]
You can use a async_std::future::timeout
or tokio::time::timeout
. Example using async_std:
use async_std::future;
use std::time::Duration;
let max_duration = Duration::from_millis(100);
assert!(timeout(max_duration, tx2.commit()).await.is_err());
If you want to continue to tx2
before completing tx1
, you can async_std::task::spawn
or tokio::spawn
the tx1 first:
async_std::task::spawn(async move {
assert!(tx1.commit().await.is_ok());
});